20-F/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 20-F/A

Amendment No. 1

(Mark One)

☐ REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934

OR

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2017

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from                      to                     

OR

☐ SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of event requiring this shell company report

Commission file number 000-38259

ABLYNX NV

(Exact name of Registrant as specified in its charter and translation of Registrant’s name into English)

Belgium

(Jurisdiction of incorporation or organization)

Technologiepark 21

9052 Ghent/Zwijnaarde, Belgium

(Address of principal executive offices)

Dr. Edwin Moses, Ph.D.

Chief Executive Officer

Ablynx NV

Technologiepark 21

9052 Ghent/Zwijnaarde, Belgium

Tel: +32 9 262 00 00 Fax: +32 9 262 001

(Name, Telephone, E-mail and/or Facsimile number and Address of Company Contact Person)

Securities registered or to be registered pursuant to Section 12(b) of the Act.

Title of each class	Name of each exchange on which registered
American Depositary Shares, each representing one ordinary share, no par value per share	The Nasdaq Stock Market LLC
Ordinary shares, no par value per share*	The Nasdaq Stock Market LLC*

* Not for trading, but only in connection with the registration of the American Depositary Shares.

Securities registered or to be registered pursuant to Section 12(g) of the Act. None

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act. None

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report.

Ordinary shares, no par value per share: 74,720,644 as of December 31, 2017

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    ☐  Yes    ☒  No

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    ☐  Yes     ☒  No

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    ☒  Yes     ☐  No

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files.    ☐  Yes     ☒  No

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer. See definition of “accelerated filer and large accelerated filer” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer  ☒             Accelerated filer  ☐             Non-accelerated filer   ☐             Emerging Growth company  ☒

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

U.S. GAAP  ☐ International Financial Reporting Standards as issued by the International Accounting Standards Board  ☒ Other  ☐

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.    ☐  Item 17    ☐  Item 18

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    ☐  Yes    ☒  No

Explanatory Note

This Amendment No. 1 to the Annual Report on Form 20-F of Ablynx NV for the year ended December 31, 2017 (the “2017 20-F”), which was filed with the Securities and Exchange Commission on March 26, 2018, is being filed solely to furnish Exhibit 101 in accordance with Rule 405 of Regulation S-T. Exhibit 101, which contains interactive data files in eXtensible Business Reporting Language (XBRL), was not previously filed with the 2017 20-F due to the 30-day grace period for initial interactive data submission.

Except as described above, this Amendment No. 1 does not, and does not purport to, amend, update or restate any information set forth in the 2017 20-F or reflect any events that occurred subsequent to the filing of the 2017 20-F on March 26, 2018.

Item 19 Exhibits

101.INS*	XBRL Instance Document
101.SCH*	XBRL Taxonomy Extension Schema Linkbase Document
101.CAL*	XBRL Taxonomy Extension Calculation Linkbase Document
101.DEF*	XBRL Taxonomy Extension Definition Linkbase Document
101.LAB*	XBRL Taxonomy Extension Label Linkbase Document
101.PRE*	XBRL Taxonomy Extension Presentation Linkbase Document

* In accordance with Rule 402 of Regulation S-T, the information in these exhibits shall not be deemed to be “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liability of that section, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act, or the Exchange Act, except as shall be expressly set forth by specific reference in such filing.

SIGNATURES

The registrant hereby certifies that it meets all of the requirements for filing on Form 20-F and that it has duly caused and authorized the undersigned to sign this Amendment No. 1 to the Annual Report on Form 20-F on its behalf.

ABLYNX NV
/s/ Edwin Moses
By:	Edwin Moses, Ph.D.
Title:	Chief Executive Officer (Principal Executive Officer)

Date: April 5, 2018

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Document and Entity Information	12 Months Ended
	Dec. 31, 2017 shares
Document - Document and Entity Information [Abstract]
Document Type	20-F/A
Amendment Flag	false
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Trading Symbol	ABLX
Entity Registrant Name	ABLYNX NV
Entity Central Index Key	0001617582
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding	74,720,644

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Consolidated statement of Financial Position - EUR (€) € in Thousands		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
ASSETS
Intangible assets		€ 1,234	€ 1,585	€ 339
Property, plant & equipment		3,876	3,746	2,620
Restricted cash		1,601	1,600	1,648
Non-current other financial assets		49,718
Non-current research and development incentives receivable		22,081	17,642	14,517
Non-currentassets		78,510	24,573	19,124
Trade and other receivables		3,656	4,831	9,286
Current research and development incentives receivable		2,449	1,879	1,238
Other current assets		2,286	1,641	1,030
Other financial assets		287,996	180,484	230,992
Cash and cash equivalents		14,951	53,356	3,602
Current assets		311,338	242,191	246,148
Total assets		389,848	266,764	265,272
EQUITY AND LIABILITIES
Share capital		117,821	106,057	96,287
Share premium account		425,291	252,297	187,316
Reserves		8,668	8,093	6,610
Accumulated losses		(371,924)	(263,391)	(262,304)
Equity attributable to the equity holders		179,856	103,055	27,909
Financial liabilities		155,169	104,349	134,828
Non-current deferred income	[1]	10,791	11,504	30,385
Non-current liabilities		165,960	115,853	165,213
Trade and other payables		22,127	25,738	16,412
Current deferred income	[1]	21,905	22,118	55,738
Current liabilities		44,032	47,856	72,150
Total equity and liabilities		€ 389,848	€ 266,764	€ 265,272

[1] This consolidated statement of Financial Position has been restated to present deferred income in current and non-current deferred income. In previously published financial statements, deferred income was presented solely under current liabilities. We refer to note 18.

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Consolidated statement of Operations - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Profit or loss [abstract]
Revenue	€ 55,562	€ 84,773	€ 76,761
Grant income	(31)	414	779
Total revenue and grant income	55,531	85,187	77,540
Research and development expenses	(90,920)	(100,315)	(83,084)
General and administrative expenses	(18,805)	(13,472)	(11,411)
Operating loss	(54,195)	(28,600)	(16,955)
Financial income	449	34,761	1,768
Financial expenses	(54,787)	(7,248)	(39,360)
Loss before taxes	(108,532)	(1,087)	(54,547)
Income taxes	0	0	0
Loss for the period	(108,532)	(1,087)	(54,547)
Loss attributable to equity holders	€ (108,532)	€ (1,087)	€ (54,547)
Basic loss per share	€ (1.74)	€ (0.02)	€ (1.00)
Diluted loss per share	€ (1.74)	€ (0.43)	€ (1.00)

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Consolidated statement of Changes in Equity - EUR (€) € in Thousands	Total	Share capital [member]	Share Premium Account [member]	Reserves [member]	Accumulated Losses [member]
Balance at Dec. 31, 2014	€ 75,474	€ 91,975	€ 183,645	€ 7,615	€ (207,761)
Loss for the period	(54,547)				(54,547)
Share-based compensation	1,821			1,817	4
Exercise of warrants	5,161	4,312	3,671	(2,822)
Balance at Dec. 31, 2015	27,909	96,287	187,316	6,610	(262,304)
Loss for the period	(1,087)				(1,088)
Issue of shares	74,152	10,348	63,804
Share issue costs	(2,710)	(2,710)
Share-based compensation	2,571			2,571
Exercise of warrants	2,221	2,132	1,177	(1,088)
Balance at Dec. 31, 2016	103,055	106,057	252,297	8,093	(263,392)
Loss for the period	(108,532)				(108,532)
Issue of shares	195,327	24,580	170,747
Share issue costs	(16,071)	(16,071)
Share-based compensation	2,606			2,606
Exercise of warrants	3,471	3,254	2,247	(2,030)
Balance at Dec. 31, 2017	€ 179,856	€ 117,821	€ 425,291	€ 8,668	€ (371,924)

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Consolidated statement of Cash Flows - EUR (€) € in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of cash flows [abstract]
Loss before taxes		€ (108,532)	€ (1,087)	€ (54,547)
Adjustments for:
Amortization expense		841	484	201
Depreciation expense		2,193	1,761	1,140
Share-based compensation expense		2,606	2,571	1,821
Net financial income		(49)	(298)	(1,101)
Net loss/(gain) arising on the convertible bond designated as at fair value through profit or loss		46,642	(34,334)	34,646
Financial expense recognized in respect of the convertible bond		7,427	7,105	4,623
Movements in working capital:
(Increase)/Decrease in trade and other receivables		(4,479)	86	(11,647)
(Decrease)/Increase in trade and other payables		(4,537)	(43,184)	(45,196)
Net cash flows used in operations		(57,889)	(66,896)	(70,060)
Interests paid		0	(1)	(1)
Interests received		49	298	1,101
Net cash flows used in operating activities		(57,840)	(66,599)	(68,960)
Purchase of intangible assets		(490)	(1,730)	(101)
Purchase of property, plant and equipment		(2,323)	(2,887)	(1,459)
Sale of current financial assets		130,489	123,859	168,253
Purchase of current financial assets		(287,718)	(73,301)	(206,371)
Net cash flows (used in)/from investing activities		(160,042)	45,941	(39,678)
Proceeds from issuance of ordinary shares (net of share issue costs)	[1]	179,256	71,442
Proceeds from exercise of warrants		3,471	2,220	5,160
Proceeds from issuance of convertible bond (net of transaction costs)				97,185
Interests paid on convertible bond		(3,250)	(3,250)	(1,625)
Repayment of borrowings				(141)
Net cash flows from financing activities		179,477	70,412	100,579
Net (decrease)/increase in cash and cash equivalents		(38,405)	49,754	(8,059)
Cash and cash equivalents at the beginning of the period		53,356	3,602	11,661
Exchange gains/(losses) in cash and cash equivalents		0	0	0
Cash and cash equivalents at the end of the period		€ 14,951	€ 53,356	€ 3,602

[1] The gross cash flow from the issue of shares amount to €195.3 million. The Company paid €16.1 million with respect to issuance costs

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Consolidated statement of Cash Flows (Parenthetical) € in Millions	12 Months Ended
	Dec. 31, 2017 EUR (€)
Statement of cash flows [abstract]
Gross proceeds from issuance of stocks	€ 195.3
Payment of stock issuance costs	€ 16.1

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CORPORATE INFORMATION

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

CORPORATE INFORMATION

1 CORPORATE INFORMATION

Ablynx NV (the “Company”) is a public limited liability company organized and existing under the laws of Belgium with registered offices at Technologiepark 21, 9052 Ghent/Zwijnaarde, Belgium (company number 0475.295.446 (RPR Ghent)).

Since October 2017, the Company has one fully owned subsidiary, Ablynx, Inc. As such, these financial statements are the consolidated financial statements of the Company. In the notes to the consolidated financial statements, references to “the Group” include the Company together with its subsidiary.

Ablynx is a biopharmaceutical company engaged in the development of Nanobodies^®, proprietary therapeutic proteins based on single-domain antibody fragments, which combine the advantages of conventional antibody drugs with some of the features of small-molecule drugs. Ablynx is dedicated to creating new medicines which will make a real difference to society. Today, the Company has more than 45 proprietary and partnered programmes in development in various therapeutic areas including inflammation, haematology, immuno-oncology, oncology and respiratory disease. The Company has collaborations with multiple pharmaceutical companies including AbbVie; Boehringer Ingelheim; Eddingpharm; Merck & Co., Inc., Kenilworth, New Jersey, USA; Merck KGaA; Novo Nordisk; Sanofi and Taisho Pharmaceuticals.

The Company has been listed on Euronext Brussels since 2007.

The Company has been listed on Nasdaq since 2017.

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BASIS OF PREPARATION

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

BASIS OF PREPARATION

2 BASIS OF PREPARATION

The financial statements have been prepared in accordance with the International Financial Reporting Standards (IFRS), issued by the International Accounting Standards Board (IASB) and the interpretations issued by the IASB’s International Financial Reporting Interpretation Committee, and Belgian legal requirements applicable to the Company. The financial statements provide a general overview of the Company’s activities and the results achieved.

The financial statements are presented in thousands of euro (unless stated otherwise) and figures are rounded to the nearest thousand (€000).

The financial statements have been prepared on a going concern basis. These financial statements have been prepared on a historical cost basis, except for financial liabilities (including derivative instruments) at fair value through profit or loss.

The preparation of financial statements in compliance with IFRS, as issued by the IASB, requires the use of certain critical accounting estimates. It also requires management to exercise its judgment in the process of applying the Company’s accounting policies. The areas involving a higher degree of judgment or complexity, or areas where assumptions and estimates are significant to the financial statements are disclosed in Note 4.

The principal accounting policies applied in the preparation of the above financial statements are set forth below.

Relevant standards and interpretations applicable for the annual period beginning on January 1, 2017

In the current year, the Company has applied a number of amendments to IFRSs issued by the International Accounting Standards Board (IASB) that are mandatorily effective for an accounting period that begins on or after January 1, 2017.

• Amendments to IAS 7 Statement of Cash Flows – Disclosure Initiative

Relevant standards and interpretations published, but not yet applicable for the annual period beginning on January 1, 2017

The Company has not applied the following new and revised IFRSs that have been issued but are not yet effective:

• IFRS 9 Financial Instruments and subsequent amendments (applicable for annual periods beginning on or after January 1, 2018);

• IFRS 15 Revenue from Contracts with Customers (applicable for annual periods beginning on or after January 1, 2018);

• IFRS 16 Leases (applicable for annual periods beginning on or after January 1, 2019);

• Amendments to IFRS 2 Classification and Measurement of Share-based Payment Transactions (applicable for annual periods beginning on or after January 1, 2018);

The above mentioned standards will not have a material impact on the financial statements of the Company, except for the standards listed below:

IFRS 9 Financial Instruments and subsequent amendments

The Company has considered the possible impact of IFRS 9 on the classification and impairment of financial instruments.

• Classification: Based on its assessment, the Company does not believe that the new classification requirements will have a material impact on its accounting

• Impairment: The Company estimates that there will not be any impact from the IFRS 9 adoption.

IFRS 15 Revenue from Contracts with Customers

IFRS 15 is to be applied for the reporting periods beginning on January 1, 2018. The new standard defines a five-step model to recognize revenue based on contracts with customers and replaces the current standards IAS 18 and IAS 11 as well as their interpretations. The timing of the revenue recognition can take place over time or at a

point in time, depending on the transfer of control.

Currently, the Company is only generating revenue from collaborative arrangements with pharmaceutical companies (for more details, we refer to Note 20). The revenue generated consists of non-refundable upfront fees, R&D service fees, milestone payments and license fees.

We have considered the possible impact of IFRS15 on revenue recognition and have decided to apply the Modified Retrospective Approach as of January 1, 2018. We will retain prior period figures as reported under the previous standards, recognising the cumulative effect of applying IFRS15 as an adjustment to the opening balance of equity as at January 1, 2018.

Ablynx generally enters into collaboration agreements that include the transfer of a license combined with the delivery of further R&D services. Under IFRS 15, the determination of the concept of ‘single combined performance obligation’ is relevant, as we could consider that the license has no stand-alone value without Ablynx being further involved in the R&D collaboration and that there is interdependence between the license and the R&D services to be provided. For certain arrangements, we could consider that there is a transformational relationship between the license and the R&D services to be delivered. We could estimate that the Ablynx’ activities during the R&D collaboration are going to significantly add to Intellectual Property (IP) and thereby the value of the programs. This aspect of the IFRS15 impact analysis is still subject to further analysis, but we anticipate the impact to be mainly affecting the recognition of milestone payments. Under IFRS 15, our milestone payments will generally have to be recognized pro rata the completion of the delivery of the services under the contract, whereas under IAS18 these were recognized when the milestone was achieved.

IFRS 16 Leases

IFRS 16 Leases will be effective for the reporting periods beginning on January 1, 2019. The new standard will replace the current standard IAS 17 Leases. In accordance with the new standard, the lessee will recognize assets and liabilities for the rights and obligations created by leases. The new standard will increase interest-bearing liabilities and property, plant and equipment in the financial statements of the Company. In addition, the rental expenses recognized in profit or loss will decrease and depreciation and amortization as well as interest expense will increase. This will affect operating profit. The impact of this new standard is currently being assessed. The Company expects the main impact to be for leases that are currently classified as operating leases and for which the Company acts as a lessee. As at December 31, 2017, the Company has non-cancellable operating lease commitments of €13.5 million, which are detailed in Note 25.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

3 SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Foreign currency translation

Functional and presentation currency

The financial statements are presented in euro, which is the Company’s functional and presentation currency.

Transactions and balances

Transactions in foreign currencies are translated at the exchange rates prevailing at the dates of the transactions, and foreign exchange differences arising on translation are recognized in the statement of comprehensive income. Monetary assets and liabilities denominated in foreign currencies are translated at the exchange rate prevailing at the reporting date, and foreign exchange differences arising on translation are recognized in profit or loss and other comprehensive income. Non-monetary assets and liabilities denominated in foreign currencies are translated at the foreign exchange rate ruling at the date of the transaction.

The following foreign exchange rates have been used for the preparation of the accounts:

	Closing rate						Average rate
€1 = x foreign currency	2017		2016		2015		2017		2016		2015
US Dollar		1.1999		1.0522		1.0866		1.1271		1.1059		1.1135
GB Pound		0.8886		0.8533		0.7360		0.8724		0.8131		0.7267

Revenue recognition

The Company generates revenue from research collaborations and government grants.

Revenue is recognized when it is probable that future economic benefits will flow to the Company and these benefits can be measured reliably. Further, revenue recognition requires that all significant risks and rewards of ownership of the goods included in the transaction have been transferred to the buyer or when the related services are performed and specific criteria have been met for each of the Company’s activities as described below.

Collaboration and alliance agreements with the Company’s commercial partners for research and development activities typically contain license fees, non-refundable upfront access fees, research and development service fees and milestone payments. Deferred income represents amounts received prior to revenue being earned.

Collaborations

Upfront fees

Non-refundable upfront fees for access to prior research results and databases are recognized when earned, if the Company has no continuing performance obligations and all conditions and obligations are fulfilled (after the delivery of the required information). If the Company has continuing performance obligations towards the client (continuing involvement), the upfront fee received is deferred and recognized over the estimated period of involvement or based on the costs incurred under the related project. Periodically the Company reassesses the estimated time and cost to complete the project phase and adjusts the period over which the revenue is deferred accordingly.

Research and development service fees

Research and development service fees are recognized as revenue over the life of the research agreement as the required services are provided and costs are incurred. These services are usually in the form of a defined number of full-time equivalents of employees (FTE) at a specified rate per FTE.

Commercial collaborations resulting in a reimbursement of research and development costs are recognized as revenue as the related costs are incurred. The corresponding research and development expenses are included in research and development expenses in the financial statements.

Milestone payments

Revenue associated with performance milestones is recognized based upon the achievement of the milestone event if the event is substantive, objectively determinable and represents an important point in the development life cycle of the product candidate.

License fees and royalties

License fees are recognized when the Company has fulfilled all conditions and obligations. The license fee will not be recognized if the amount cannot be reasonably estimated and if the payment is doubtful. As the Company has a continuing involvement during the license period, license fees are recognized evenly over the term of the agreement.

Royalty revenues are recognized when the Company can reliably estimate such amounts and collectability is reasonably assured. As such, the Company generally recognizes royalty revenues in the period in which the licensees are reporting the royalties to the Company through royalty reports. Under this accounting policy, the royalty revenues the Company reports are not based upon the Company’s estimates and such royalty revenues are typically reported in the same period in which the Company receives payment from its licensees.

Government grants

Because it carries out research and development activities, the Company benefits from various grants and research and development incentives from certain governmental agencies. These grants and research and development incentives generally aim to partly reimburse approved expenditures incurred in research and development efforts of the Company.

The Company recognizes a government grant only when there is reasonable assurance that the Company will comply with the conditions attached to the grant and the grant will be received. As such, a receivable is recognized in the statement of financial position and measured in accordance with the related accounting policy mentioned below.

Government grants are recognized in profit or loss on a systematic basis over the periods in which the Company recognizes as expenses the related costs which the grants are intended to compensate. As a result, grants relating to costs that are recognized as intangible assets or property, plant and equipment (grants related to assets or investment grants) are deducted from the carrying amount of the related assets and recognized in the profit or loss statement consistently with the amortization or depreciation expense of the related assets. Grants that intend to compensate costs are released as income when the subsidized costs are incurred, which is the case for grants relating to research and development costs.

Government grants that become receivable as compensation for expenses or losses already incurred are recognized in profit or loss of the period in which they become receivable.

The portion of grants not yet released as income is presented as deferred income in the statement of financial position. In the statement of comprehensive income, government grants are presented as grant income.

Research and development incentives receivables

Non-current research and development incentives receivables are discounted over the period until maturity date according to the appropriate discount rates.

Intangible assets

Internally generated intangible assets

Research expenses are charged to the statement of comprehensive income as incurred. Development costs are only capitalized if the following conditions are met:

• the technical feasibility of completing the intangible asset;

• the intention to complete the intangible asset and use or sell it;

• the generation of probable future economic benefits;

• the availability of adequate technical, financial and other resources to complete the development and to use or sell the intangible asset; and

• its ability to measure reliably the expenditure attributable to the intangible asset during its development.

At present, the current stage of research activities does not allow any capitalization of intangible assets. The existing regulatory and clinical risks constitute an important uncertainty with respect to the capitalization of development costs. The research and development expenses are not capitalized, as long as the criteria under IFRS are not met.

As no internally generated assets are recognized, all costs with respect to the protection of intellectual property are expensed as research and development expenses.

Purchased intangible assets

Acquired computer software licenses are capitalized based on the costs incurred to acquire and bring to use the specific software. These costs are amortized on a straight-line basis over their estimated useful lives of maximum three years.

Acquired knowledge in the form of licenses and patents is recorded at cost less accumulated amortization and impairment. It is amortized on a straight-line basis over the shorter of the term of the license agreement and its estimated useful life.

The Company does not have intangible fixed assets with an indefinite useful life.

Property, plant and equipment

An item of property, plant and equipment is carried at historical cost less accumulated depreciation and impairment. Costs relating to the day-to-day servicing of the item are recognized in the income statement as incurred.

A pro rata straight-line depreciation method is used to reflect the pattern in which the asset’s future economic benefits are expected to be consumed by the entity. However, land is not depreciated. The residual value and the useful life of an asset is reviewed each financial year-end for possible impairment.

Depreciation is charged to the income statement on the following basis:

•   Buildings	10 years
•   Equipment	3 years
•   Hardware	3 years
•   Furniture	5 years
•   Equipment under leasing	The shorter of the useful life or the minimum leasing term
•   Leasehold improvements	The shorter of the useful life or the minimum leasing term

Impairment of non-financial assets

Assets that have an indefinite useful life are not subject to amortization and are tested annually for impairment. Assets that are subject to amortization or depreciation are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset’s fair value less costs to sell and value in use.

Assets other than goodwill that suffered impairment are reviewed for possible reversal of the impairment at each reporting date.

Leases

Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards incident to ownership of an asset. All other leases are classified as operating leases. Classification is made at the inception of the lease.

Assets held under finance leases by the Company are recognized as assets at their fair value or, if lower, at the present value of the minimum lease payments, using the interest rate implicit in the lease as the discount rate. The corresponding liability is included in the statement of financial position as a finance lease obligation. Assets

held under finance leases are depreciated over their estimated useful life on a systematic basis consistent with the depreciation policy for depreciable assets that are owned by the Company or, if shorter, over the lease term.

Lease payments are apportioned between finance expenses and the reduction of the lease obligation.

Initially incurred costs, directly attributable to the arrangement of the finance lease, are added to the amount recognized as an asset.

Assets held by the Company under operating leases are not recognized in the statement of financial position. Operating lease payments are recognized as expenses in the period in which they are incurred on a straight-line basis over the lease term.

Financial assets

Financial assets are classified into the following specified categories: financial assets “at fair value through profit or loss” (FVTPL), “held-to-maturity” investments, “available-for-sale” (AFS) financial assets and “loans and receivables”. The classification depends on the nature and purpose of the financial assets and is determined at the time of initial recognition and reviewed at each reporting date.

At this moment, the Company only has financial assets classified as “loans and receivables”, which includes trade receivables.

Purchase and sale of financial assets are recognized on the settlement date, which is the date an asset is delivered to or by the Company. The cost of financial assets includes transaction costs.

Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted in an active market. Loans and receivables (including trade and other receivables, bank balances and cash) are measured at amortized cost using the effective interest method, less any impairment.

The effective interest method is a method of calculating the amortized cost of a debt instrument and of allocating interest income over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash receipts (including all fees and points paid or received that form an integral part of the effective interest rate, transaction costs and other premiums or discounts) through the expected life of the debt instrument, or, where appropriate, a shorter period, to the net carrying amount on initial recognition.

Financial assets are assessed for indicators of impairment at the end of each reporting period. Financial assets are considered to be impaired when there is objective evidence that, as a result of one or more events that occurred after the initial recognition of the financial asset, the estimated future cash flows of the investment have been affected.

For financial assets measured at amortized cost, if, in a subsequent period, the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized, the previously recognized impairment loss is reversed through profit or loss to the extent that the carrying amount of the investment at the date the impairment is reversed does not exceed what the amortized cost would have been had the impairment not been recognized.

Cash and cash equivalents

Cash and cash equivalents consists of cash, deposits held at call with banks and short-term deposits with an initial maturity not exceeding one month.

Equity instruments

Equity instruments issued by the Company are recorded at the proceeds received, net of direct issue costs.

Where the Company purchases the Company’s equity share capital (treasury shares), the consideration paid, including any directly attributable incremental costs (net of income taxes) is deducted from equity attributable to the Company’s equity holders until the shares are cancelled, reissued or disposed of. Where such shares are subsequently sold or reissued, any consideration received, net of any directly attributable incremental transaction costs and the related income tax effects is included in equity attributable to the Company’s equity holders.

Financial liabilities

Convertible bond

The Company’s convertible senior notes due 2020 (the convertible bond) are accounted for in accordance with IAS 39 Financial Instruments: Recognition and Measurement and IAS 32 Financial Instruments: Presentation. Since the Company has a cash alternative election, it has a choice over how the share conversion option will be settled (net in cash or by exchanging shares for cash). Therefore, the share conversion option is a derivative at FVTPL according to IAS 39, and not an own equity instrument. As such, the convertible bond consists of a host debt instrument and an embedded share conversion option.

The value assigned to the host debt instrument is the estimated fair value, as of the issuance date. Subsequent to initial recognition, the debt instrument will be measured at amortized cost, using the effective interest rate method.

The embedded derivative was measured initially at fair value (estimated as the difference between the fair value of the total convertible bond and the fair value of the host debt) and subsequently at FVTPL.

The Company has no other derivative financial instruments.

Trade payables

Trade payables within one year are measured at amortized cost ( i.e., at the net present value of the payable amount). Unless the impact of discounting is material, the nominal value is considered.

Provisions

A provision is recognized when the Company has a present obligation (legal or constructive) as a result of past events, it is probable (more likely than not) that a transfer of economic benefits will be required to settle the obligation, and a reliable estimate can be made of the amount of the obligation.

The amount recognized as a provision is the best estimate of the consideration required to settle the present obligation at the end of the reporting period. When the impact is likely to be material (for long-term provisions), the amount recognized as a provision is estimated on a net present value basis (discount factor). The increase in provision due to the passage of time is recognized as an interest expense.

A present obligation arises from an obligating event and may take the form of either a legal obligation or a constructive obligation (a constructive obligation exists when the Company has an established pattern of past practice that indicates to other parties that it will accept certain responsibilities and as a result has created a valid expectation on the part of those other parties that it will discharge those responsibilities). An obligating event leaves the Company no realistic alternative to settling the obligation, independently of its future actions.

Employee benefits

The Company offers several post-employment, death, disability and healthcare benefit schemes. All employees have access to these schemes. The death, disability and healthcare benefits granted to employees of the Company are covered by external insurance companies, where premiums are paid annually and charged to the income statement as they were incurred.

The post-employment pension plans granted to employees of the Company are based on defined contributions for which the insurance company guarantees a defined interest until retirement (type ‘branche 21/tak21’).

As a consequence of the law of December 1, 2015, minimum returns are guaranteed by the employer as follows:

• for the contributions paid as from January 1, 2016, a new variable minimum return based on OLO rates, with a minimum of 1.75% and a maximum of 3.75%. In view of the low rates of the OLO in the last years, the return has been initially set to 1.75%;

• for the contributions paid until end December 2015, the previously applicable legal returns (3.25% and 3.75% respectively on the employer and employee contributions) continue to apply until retirement date of the participants.

In view of the minimum returns guarantees, those plans qualify as Defined Benefit plans.

A provision has to be recognized for the sum of the positive differences, per plan participant, between the minimum guaranteed reserves and the accumulated reserves.

Income taxes

Income tax expense represents the sum of the tax currently payable and deferred tax.

In compliance with IAS 12 Income Taxes, current and deferred taxes are recognized in the statement of profit or loss, other comprehensive income or directly in equity consistently with the accounting for the underlying transaction.

The current tax expense (income) is the estimated amount of tax due on the taxable income for the period, calculated using the tax rates enacted at reporting date.

Deferred taxes result from temporary differences between the carrying amount of assets and liabilities and their tax basis. No deferred taxes are recognized for temporary differences generated by the initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit nor loss. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted by the reporting date and are expected to apply when the related deferred tax asset is realized or the deferred tax liability is settled.

Deferred tax assets are recognized to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. As such, a deferred tax asset for the carry forward of unused tax losses will be recognized to the extent that it is probable that future taxable profit will be available.

Share-based compensation transactions

The Company has offered equity-settled, share-based compensation plans to its employees, executive management and consultants. The cost with respect to the employee services received in compensation for the grant of these warrants is recognized as an expense.

The total amount of the expense is recognized over the vesting period and determined based on the fair value of the warrants at grant date. The fair value of each warrant is estimated on the date of grant using the Black-Scholes model. The total cost is initially estimated based on the number of warrants that will become exercisable. At each reporting date, the Company revises its estimates of the number of warrants that will become exercisable. The impact of the revision is recognized in the income statement over the remaining vesting period with a corresponding adjustment to equity.

Earnings/(loss)per share

Basic earnings/(loss) per share is computed on the basis of the weighted average number of ordinary shares outstanding during the period, excluding treasury shares.

Diluted earnings/(loss) per share is computed based on the weighted-average number of ordinary shares outstanding including the dilutive effect of warrants and bonds. Warrants and bonds are treated as dilutive, when and only when their conversion to ordinary shares would decrease the net profit per share from continuing operations.

Operating segments

The chief operating decision-maker, who is responsible for allocating resources and assessing performance of the Company, has been identified as the Board of Directors that makes strategic decisions.

The Company operates in one operating segment. Management has determined that there is only one operating segment based on the information reviewed by the Board of Directors. The Board of Directors considers the business of the Company from a general company-wide perspective based on the close interrelation between the different projects. No geographical financial information is currently available given the fact that the core operations are currently still in a research and development phase.

No disaggregated information on product level or geographical level or any other level is currently existing and hence also not considered by the Board for assessing performance or allocating resources.

Basis of consolidation

The consolidated financial statements incorporate the financial statements of the Company and entities controlled by the Company.

Control is achieved when the Company:

• has power over the investee;

• is exposed, or has rights, to variable returns from its involvement with the investee; and

• has the ability to use its power to affect the returns.

The Company reassesses whether or not it controls an investee if facts and circumstances indicate that there are changes to one or more of the three elements of control listed above.

Consolidation of an subsidiary begins when the Company obtains control over the subsidiary and ceases when the Company loses control of the subsidiary. Specifically, income and expenses of a subsidiary acquired or disposed of during the year are included in the consolidated statement of profit or loss and other comprehensive income from the date the Company gains control until the date when the Company ceases to control the subsidiary.

Profit or loss and each component of other comprehensive income are attributed to the owners of the Company and to the non-controlling interests. Total comprehensive income of subsidiaries is attributed to the owners of the Company and to the non-controlling interests even if this results in the non-controlling interests having a deficit balance.

When necessary, adjustments are made to the financial statements of subsidiaries to bring their accounting policies into line with the Group’s accounting policies.

All intragroup assets and liabilities, equity, income, expenses and cash flows relating to transactions between members of the Group are eliminated in full on consolidation.

Share capital

Financial instruments issued by the Group are classified as equity only to the extent that they do not meet the definition or a financial liability of financial asset. Ordinary shares are classified as equity.

Incremental costs directly attributable to the issue of new ordinary shares are presented in equity as a deduction, net of tax, from the proceeds.

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SIGNIFICANT ACCOUNTING JUDGMENTS, ESTIMATES AND ASSUMPTIONS

12 Months Ended

Dec. 31, 2017

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SIGNIFICANT ACCOUNTING JUDGMENTS, ESTIMATES AND ASSUMPTIONS

4 SIGNIFICANT ACCOUNTING JUDGMENTS, ESTIMATES AND ASSUMPTIONS

At each reporting date, the Company makes estimates with respect to the impact of past events on the future resulting in a number of accounting estimates.

Convertible bond

For the Company’s convertible bond, the significant judgment relates to the determination of the fair value of the embedded, not-closely-related, share conversion derivative, which also includes the early redemption optionality, both at inception and subsequently at each reporting date.

The measurement approach taken for the fair value of the embedded derivative is based on the difference between the fair value of the total convertible bond as a whole and the fair value of the host debt (non-prepayable non-convertible debt).

An estimate of the fair value of the convertible bond is obtained from a reputable data provider. At inception and subsequently, this fair value was based on indicative (i.e. non-executable) quotes provided by market participants resulting in indicative prices that were given a high reliability score by the data provider.

The estimate of the fair value of the host debt was based on credit spread data for debt issued by comparable companies, provided by a third party.

The embedded derivative amounts to €66.5 million at closing 2017 (2016: €19.8 million; 2015: €54.1 million).

Consequently, the fair value of the combined embedded derivative thus obtained is a “level 3” fair value measurement according to the fair value hierarchy of IFRS 13 Fair Value Measurement. Disclosures on this level

3 fair value measurement, including a sensitivity analysis for reasonably possible changes in assumptions are provided in Note 5.

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FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT Overview of financial instruments

12 Months Ended

Dec. 31, 2017

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FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT Overview of financial instruments

5 FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT Overview of financial instruments

	As at December 31,
€ in thousands	2017		2016		2015
Financial assets		356,377		238,952		243,024
Restricted cash		1,601		1,600		1,648
Trade receivables		2,111		3,512		6,782
Current financial assets		337,714		180,484		230,992
Cash and cash equivalents		14,951		53,356		3,602
Total financial assets		356,377		238,952		243,024
At fair value through profit or loss		66,454		19,812		54,146
Convertible bond - Embedded derivative		66,454		19,812		54,146
At amortized cost		104,280		104,856		92,338
Convertible bond - Host debt		88,715		84,537		80,682
Total Trade payables		15,565		20,319		11,656
Total financial liabilities		170,734		124,668		146,484

Fair value of financial instruments

IFRS 13 requires disclosure of fair value measurements by level of the following hierarchy:

• Level 1: Quoted (unadjusted) prices in active markets for identical assets or liabilities;

• Level 2: Other techniques for which all inputs which have a significant effect on the recorded fair value are observable, either directly or indirectly;

• Level 3: Techniques which use inputs which have a significant effect on the recorded fair value that are not based on observable market data.

The carrying amounts of other financial assets recognized in the financial statements approximate their fair values, as cash and cash equivalents, short-term deposits and trade receivables primarily have short terms to maturity. The same situation is applicable for financial liabilities, except for the convertible bond.

The following table presents the fair values of the components of the convertible bond and the related fair value (FV) level:

€ in thousands	Carrying amount		Fair Value		Level of FV hierarchy IFRS 13
At 31 December 2017
Financial assets
Other financial assets		49,718		49,718		Level 3
As at December 31, 2017
Convertible bond
Host debt		88,715		97,296		Level 2
Embedded derivative		66,454		66,454		Level 3
As at December 31, 2016
Convertible bond
Host debt		84,537		88,708		Level 2
Embedded derivative		19,812		19,812		Level 3
As at December 31, 2015
Convertible bond
Host debt		80,682		84,798		Level 2
Embedded derivative		54,146		54,146		Level 3

The fair value of the host debt of the convertible bond measured at amortized cost in the statement of financial position has been determined in accordance with generally accepted pricing models based on discounted cash flow analysis, with the most significant inputs being the discount rate that reflects the credit risk. The estimate of the fair value of the host debt was based on credit spread data for debt issued by comparable companies, provided by third parties.

The measurement approach taken for the fair value of the embedded derivative is based on the difference

between the fair value of the total convertible bond as a whole and the fair value of the host debt (non-prepayable non-convertible debt). An estimate of the fair value of the convertible bond is obtained from a reputable data provider. At inception and subsequently, this fair value has been based on indicative (i.e. non-executable) quotes provided by market participants resulting in indicative prices that were given a high reliability score by the data provider.

Reconciliation of the Level 3 instrument:

At issuance of other financial assets	50,000
Included in profit or loss	(278)
Closing Balance December 31, 2017	49,723
At issuance of the convertible bond	19,500
Included in profit or loss as a change in fair value	34,646
Closing Balance December 31, 2015	54,146
Included in profit or loss as a change in fair value	(34,334)
Closing Balance December 31, 2016	19,812
Included in profit or loss as a change in fair value	46,642
Closing Balance December 31, 2017	66,454

The sensitivity of the fair value to significant non-observable inputs:

Assumptions as at December 31, 2017	Fair value other financial asset
Credit spread		31 bps	49,718
Sensitivity analysis
Credit spread
+1 bps		32 bps	49,704
- 1 bps		30 bps	49,729
Assumptions as at December 31, 2017	Fair value embedded derivative convertible bond
Credit spread		450 bps	66,454
Share price	€	20.72
Sensitivity analysis
Credit spread
-100 bps		350 bps	64,157
+100 bps		550 bps	68,671
Share price
+1%	€	20.93	68,077
-1%	€	20.51	64,803
Assumptions as at December 31, 2016	Fair value embedded derivative convertible bond
Credit spread		700 bps	19,812
Share price	€	10.82
Sensitivity analysis
Credit spread
-100 bps		600 bps	20,149
+100 bps		800 bps	19,497
Share price
+1%	€	10.92	19,900
-1%	€	10.71	19,726
Assumptions as at December 31, 2015	Fair value embedded derivative convertible bond
Credit spread		700 bps	51,405
Sensitivity analysis
Credit spread
-200 bps		500 bps	54,534
+200 bps		900 bps	48,802

Financial risk factors

Liquidity risk management

The Company makes use of term accounts, treasury notes and equity and credit linked notes. The maturities of the term deposits are limited to a maximum of one year. The maturities of the credit linked notes are limited to a maximum of 2 years.

The Company has €1.6 million restricted cash related to a cash pledge as at December 31, 2017 (€1.6 million as at December 31, 2016 and €1.6 million as at December 31, 2015).

For the maturity table relating to the convertible bond, we refer to note 16. No cash credit lines were available.

Furthermore, the Company is not subject to any covenants relating to its borrowings.

Interest rate risk

The Company has a material interest-bearing liability related to the private placement of €100 million senior unsecured bonds with a 3.25% coupon rate and a conversion price of €12.66 (original conversion price was €12.93).

The Company does not have any floating rate financial instruments.

Credit risk

The credit risk arises from outstanding transactions with customers. It is the Company’s policy to deal with creditworthy partners to avoid significant risk exposure. The trade receivables relate to a limited number of high-ranked international customers for whom there is no recent history of default. The credit risk is highly concentrated around a limited number of customers.

Available liquidities are placed with several financial institutions.

The financial institutions have credit ratings varying from A+, over A to A-.

No cash credit lines were available.

Credit quality of financial assets:

				As at December 31,
€ in thousands	Rating			2017		2016		2015
Cash and cash equivalents		A	+		9,465		35,131		3,522
		A			4,035				38
		A	-		1,451		18,225		42
					14,951		53,356		3,602
Current financial assets		A	+		99,996		100,003		56,026
		A			10,000		0		73,500
		A	-		227,718		80,481		101,466
					337,714		180,484		230,992
Total		A	+		109,461		135,134		59,548
		A			14,035		0		73,538
		A	-		229,169		98,706		101,508
					352,665		233,840		234,594

Source of December 31, 2017 – Fitch

Foreign exchange risk

The Company has sales transactions from research and collaboration agreements denominated in USD and purchase transactions denominated in AUD, BGN, CAD, DKK, CHF, GBP, JPY, NOK, PLN, SEK and USD. The Company did not enter into any currency hedging arrangements in order to cover this risk.

As per December 31, 2017, if the EUR had weakened 10% against the GBP and against the USD with all other variables held constant, the loss for the period would have been €2.437.311 higher (2016: loss €675.710 higher). Conversely, if the EUR had strengthened 10% against the GBP and against the USD with all other variables held constant, the loss of the period would have been €1.994.163 lower (2016: loss €552.854 lower).

The table below provides an indication of the Company’s open net foreign currency position as per year end:

	As at December 31,
€ in thousands	2017		2016		2015
Liabilities denominated in USD		180		608		142
Liabilities denominated in GBP		182		167		76
Assets denominated in USD		105		65		2,680

Capital risk management

The Company manages its capital to ensure that it will be able to continue as a going concern. The capital structure of the Company consists of financial debt, cash and cash equivalents, restricted cash, current financial assets and equity attributed to the holders of equity instruments of the Company, such as capital, reserves and results carried forward as mentioned in the statements of changes in equity. The Company makes the necessary adjustments in the light of changes in the economic circumstances, risks associated to the different assets and the projected cash needs of the current and projected research activities. The current cash situation and the anticipated cash generation are the most important parameters in assessing the capital structure. The Company objective is to maintain the capital structure at a level to be able to finance its activities for at least twelve months. Cash income from existing and new partnerships is taken into account and, if needed and possible, the Company can issue new shares or enter into financing agreements.

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SEGMENT INFORMATION

12 Months Ended

Dec. 31, 2017

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SEGMENT INFORMATION

6 SEGMENT INFORMATION

The Company does not distinguish different operating segments.

The income was derived from five pharmaceutical partners, namely AbbVie, Merck KGaA, Merck & Co., Inc., Sanofi and Novo Nordisk. Moreover, in 2017 more than 80% of the income originated from three parties, one party was responsible for 29% of the income, two other parties represented 27% each.

In 2016 more than 85% of the income originated from three parties, one party was responsible for more than 40% of the income, two other parties represented between 19% and 25% each. In 2015, one party represented more than 50% of the revenues, two other parties represented between 15% and 23% each.

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INTANGIBLE ASSETS

12 Months Ended

Dec. 31, 2017

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INTANGIBLE ASSETS

7 INTANGIBLE ASSETS

€ in thousands	Patents			Software			Total
Cost		2,174			2,473			4,647
Accumulated amortization and impairment		(2,080	)		(2,128	)		(4,208	)
Carrying amount at January 1, 2015		94			345			439
Additions		0			101			101
Amortization expense		(7	)		(194	)		(201	)
Carrying amount at December 31, 2015		87			252			339
Cost		2,174			2,574			4,748
Accumulated amortization and impairment		(2,087	)		(2,322	)		(4,409	)
Carrying amount at January 1, 2016		87			252			339
Additions		0			1,730			1,730
Amortization expense		(7	)		(477	)		(484	)
Carrying amount at December 31, 2016		80			1,505			1,585
Cost		2,174			4,304			6,478
Accumulated amortization and impairment		(2,094	)		(2,799	)		(4,893	)
Carrying amount at January 1, 2017		80			1,505			1,585
Additions					490			490
Amortization expense		(7	)		(833	)		(841	)
Carrying amount at December 31, 2017		72			1,162			1,234
Cost		2,174			4,794			6,968
Accumulated amortization and impairment		(2,102	)		(3,632	)		(5,734	)

The intangible assets mainly consist of a portfolio of acquired patents and software licenses.

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PROPERTY, PLANT & EQUIPMENT

12 Months Ended

Dec. 31, 2017

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PROPERTY, PLANT & EQUIPMENT

8 PROPERTY, PLANT & EQUIPMENT

€ in thousands	Land and buildings			Equipment			Furniture			Equipment under leasing			Leasehold improve- ments			Total
Cost		0			11,418			2,049			2,181			847			16,495
Accumulated depreciation and impairment		0			(10,373	)		(1,678	)		(1,388	)		(755	)		(14,194	)
Carrying amount at January 1, 2015		0			1,045			371			793			92			2,301
Additions		413			960			50			0			36			1,459
Depreciation charge		(24	)		(642	)		(223	)		(230	)		(21	)		(1,140	)
Carrying amount at December 31, 2015		389			1,363			198			563			107			2,620
Cost		413			12,378			2,099			2,181			883			17,954
Accumulated depreciation and impairment		(24	)		(11,015	)		(1,901	)		(1,618	)		(776	)		(15,334	)
Carrying amount at January 1, 2016		389			1,363			198			563			107			2,620
Additions		0			2,421			346			0			120			2,887
Depreciation charge		(34	)		(1,267	)		(179	)		(230	)		(51	)		(1,761	)
Carrying amount at December 31, 2016		355			2,517			365			333			176			3,746
Cost		413			14,799			2,445			2,181			1,003			20,841
Accumulated depreciation and impairment		(58	)		(12,282	)		(2,080	)		(1,848	)		(827	)		(17,095	)
Carrying amount at January 1, 2017		355			2,517			365			333			176			3,746
Additions					2,022			183						118			2,323
Depreciation charge		(34	)		(1,664	)		(176	)		(229	)		(89	)		(2,193	)
Carrying amount at December 31, 2017		321			2,875			372			104			205			3,876
Cost		413			16,821			2,628			2,181			1,121			23,164
Accumulated depreciation and impairment		(92	)		(13,946	)		(2,256	)		(2,077	)		(916	)		(19,288	)

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RESTRICTED CASH

12 Months Ended

Dec. 31, 2017

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RESTRICTED CASH

9 RESTRICTED CASH

Restricted cash is related to a cash pledge the Company has provided in respect of the service agreement with

Bio-Versneller NV (see note 30).

	As at December 31,
€ in thousands	2017		2016		2015
Restricted cash		1,601		1,600		1,648

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RESEARCH AND DEVELOPMENT INCENTIVES RECEIVABLES

12 Months Ended

Dec. 31, 2017

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RESEARCH AND DEVELOPMENT INCENTIVES RECEIVABLES

10 RESEARCH AND DEVELOPMENT INCENTIVES RECEIVABLES

	As at December 31,
€ in thousands	2017		2016		2015
Non-current research and development incentives receivable		22,081		17,642		14,517
Current research and development incentives receivable		2,449		1,879		1,238
Total		24,530		19,521		15,755

The Company has accounted for a research and development incentives receivable of €24.5 million as at December 31, 2017 following a research and development incentive scheme in Belgium under which the tax incentive can be refunded after five years if not offset against taxable basis over that period. The research and development incentives are recorded net against the relating research and development expenses in the statement of comprehensive income. The Company expects to receive this amount progressively over 6 years, starting as from accounting year 2018 onwards.

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TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS

12 Months Ended

Dec. 31, 2017

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TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS

11 TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS

	As at December 31,
€ in thousands	2017		2016		2015
Trade receivables		2,111		3,512		6,782
Total trade receivables		2,111		3,512		6,782
Value added tax receivables		1,162		887		626
Withholding taxes on interest income		289		420		528
Other receivables		94		12		1,350
Total other receivables		1,545		1,319		2,504
Total trade and other receivables		3,656		4,831		9,286

Trade receivables consist of amounts due from research collaboration partners. The nominal amount of both trade and other receivables is considered to be the fair value.

Other receivables mainly consist of taxes to be recovered, such as value added tax and withholding taxes.

The trade receivables relate to a limited number of partners and are considered fully recoverable. Currently, there are no past due trade receivables.

	As at December 31,
€ in thousands	2017		2016		2015
Accrued income		908		1,080		569
Deferred expenses		1,378		561		461
Total other current assets		2,286		1,641		1,030

Accrued income consists mainly of earned income from expenditure reimbursements for which no invoices have been issued, but for which the relating costs have been incurred.

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CURRENT FINANCIAL ASSETS

12 Months Ended

Dec. 31, 2017

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CURRENT FINANCIAL ASSETS

12 CURRENT FINANCIAL ASSETS

The current financial assets consist of term deposits with banks with an original maturity exceeding one month. All these term deposits are held in euro.

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CASH AND CASH EQUIVALENTS

12 Months Ended

Dec. 31, 2017

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CASH AND CASH EQUIVALENTS

13 CASH AND CASH EQUIVALENTS

	As at December 31,
€ in thousands	2017		2016		2015
Cash at bank and on hand		14,951		53,356		3,602
Total cash and cash equivalents		14,951		53,356		3,602
of which : cash and cash equivalents in Euro		14,843		53,291		922
of which : cash and cash equivalents in foreign currency		108		65		2,680

The cash and cash equivalents heading consists of cash, deposits held at call with banks and short-term deposits with an initial term not exceeding one month.

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SHARE CAPITAL

12 Months Ended

Dec. 31, 2017

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SHARE CAPITAL

14 SHARE CAPITAL

Overview of capital transactions

	Shares
Number of shares outstanding on January 1, 2015		54,014,159
Exercise of warrants - January 19, 2015		115,946
Exercise of warrants - March 16, 2015		174,302
Exercise of warrants - April 17, 2015		20,165
Exercise of warrants - June 3, 2015		83,000
Exercise of warrants - July 17, 2015		79,885
Exercise of warrants - July 29, 2015		24,967
Exercise of warrants - October 19, 2015		5,200
Exercise of warrants - December 7, 2015		7,250
Exercise of warrants - December 15, 2015		287,500
Number of shares outstanding on January 1, 2016		54,812,374
Exercise of warrants - January 18, 2016		288,170
Exercise of warrants - February 17, 2016		7,521
Exercise of warrants - March 17, 2016		210,741
Exercise of warrants - April 20, 2016		18,400
Private placement - June 1, 2016		5,533,720
Exercise of warrants - July 19, 2016		39,818
Exercise of warrants - October 18, 2016		10,050
Exercise of warrants - November 9, 2016		938
Number of shares outstanding on January 1, 2017		60,921,732
Exercise of warrants - January 17, 2017		154,342
Exercise of warrants - April 19, 2017		57,125
Exercise of warrants - July 18, 2017		19,833
Exercise of warrants - August 8, 2017		16,700
Exercise of warrants - September 13, 2017		249,563
Exercise of warrants - October 19, 2017		156,849
IPO Nasdaq - October 27, 2017		11,430,000
IPO Nasdaq - October 30, 2017		1,714,500
Number of shares outstanding on December 31, 2017		74,720,644

On January 19, 2015, the Company issued 115,946 new shares in exchange for €909,426.07 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €216,819.02 and €692,607.05 respectively.

On March 16, 2015, the Company issued 174,302 new shares in exchange for €1,292,682.18 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €325,944.74 and €966,737.44 respectively.

On April 17, 2015, the Company issued 20,165 new shares in exchange for €112,425.70 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €37,603.55 and €74,822.15 respectively.

On June 3, 2015, the Company issued 83,000 new shares in exchange for €410,955 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €155,210 and €255,745 respectively.

On July 17, 2015, the Company issued 79,885 new shares in exchange for €600,491.30 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €149,384.95 and €451,106.35 respectively.

On July 29, 2015, the Company issued 24,967 new shares in exchange for €199,086.96 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €46,688.29 and €152,398.67 respectively.

On October 19, 2015, the Company issued 5,200 new shares in exchange for €41,249 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €9,724 and €31,525 respectively.

On December 7, 2015, the Company issued 7,250 new shares in exchange for €61,390 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €13,557.50 and €47,832.50 respectively.

On December 15, 2015, the Company issued 287,500 new shares in exchange for €1,532,750 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €535,000 and €997,750 respectively.

On January 18, 2016, the Company issued 288,170 new shares in exchange for €1,192,292.70 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €538,877.90 and €653,414.80 respectively.

On February 17, 2016, the Company issued 7,521 new shares in exchange for €34,726.41 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €14,064.27 and €20,662.14 respectively.

On March 17, 2016, the Company issued 210,741 new shares in exchange for €740,375.82 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €394,085.67 and €346,290.15 respectively.

On April 20, 2016, the Company issued 18,400 new shares in exchange for €76,630 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €34,408 and €42,222 respectively.

On June 1, 2016, the Company raised €74.2 million through a private placement of new shares via an accelerated book building procedure. The Company placed 5,533,720 new shares in exchange for €74,151,848. The par value and share premium amounted to €10,348,056.40 and €63,803,791.60 respectively.

On July 19, 2016, the Company issued 39,818 new shares in exchange for €160,489.39 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €77,947.16 and €82,542.23 respectively.

On October 18, 2016, the Company issued 10,050 new shares in exchange for €47,303 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €18,793.50 and €28,509.50 respectively.

On November 9, 2016, the Company issued 938 new shares in exchange for €5,102.72 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €1,754.06 and €3,348.66 respectively.

On January 17,2017, the Company issued 154,342 new shares in exchange for €1,011,939.05 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €288,619.54 and €723,319.51 respectively.

On April 19, 2017, the Company issued 57,125 new shares in exchange for €398,801.77 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €106,823.75 and €291,978.02 respectively.

On July 18, 2017, the Company issued 19,833 new shares in exchange for €121,444.25 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €37,087.71 and €84,356.54 respectively.

On August 8, 2017, the Company issued 16,700 new shares in exchange for €80,683.50 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €31,229.00 and €49,454.50 respectively.

On September 13, 2017, the Company issued 249,563 new shares in exchange for €878,950.09 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €466,682.81 and €412,267.28 respectively.

On October 19, 2017, the Company issued 156,849 new shares in exchange for €978,878.73 as a result of the exercise of warrants by some employees and consultants of the Company. The par value and share premium amounted to €293,307.63 and €685,571.1 respectively.

On October 27, 2017, the Company raised €169.8 million through an initial public offering on Nasdaq. The Company placed 11,430,000 new shares in exchange for €169,849,800. The par value and share premium amounted to €21,374,100 and €148,475,700 respectively.

On October 30, 2017, the Company raised an additional €25.5 million through an initial public offering on Nasdaq. The Company placed 1,714,500 new shares, pursuant to the exercise of the underwriters’ over-allotment option, in exchange for €25,477,470. The par value and share premium amounted to €3,206,115 and €22,271,355 respectively.

All shares issued are fully paid.

Authorized capital

At December 31, 2017, the authorized capital amounts to €27,253 thousand (2016: €54,470 thousand; 2015: €66,520 thousand), which is available until August 7, 2018.

Voting rights

Each share gives right to one vote. If the share is encumbered by usufruct, the voting rights attached to the share shall be exercised by the usufructuary. The voting rights attached to pledged shares shall be exercised by the owner-pledger.

Dividends and profit appropriation

The Company has never distributed any dividends to its shareholders. According to Belgian company law, the Company is required to deduct at least 5% from its profit to constitute the legal reserve until it reaches one-tenth of the Company’s statutory share capital. At December 31, 2017, no profits were available for distribution.

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SHARE-BASED COMPENSATIONS

12 Months Ended

Dec. 31, 2017

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SHARE-BASED COMPENSATIONS

15 SHARE-BASED COMPENSATIONS

The Company operates an equity-based share-based compensation plan, whereby warrants are granted to directors, management and selected employees. The warrants are accounted for as equity-settled share-based compensation plans since the Company has no legal or constructive obligation to repurchase or settle the warrants in cash.

Each warrant gives the beneficiaries the right to subscribe to one common share of the Company. The warrants are granted for free and the exercise price is each time calculated based on either (i) the average closing rate of the underlying shares on Euronext Brussels during the period of thirty days preceding the date of the decision of the shareholders meeting (or the board of directors if the warrants have been issued in the context of the authorized capital), (ii) the average closing rate of the underlying shares on Euronext Brussels during a period of thirty days preceding the date of the grant, or (iii) the last closing rate of the underlying share preceding the date of the grant, as determined by the special proxyholder of the shareholders meeting of the Company (or of the Board of Directors of the Company if the warrants have been issued in the context of the authorized capital).

An overview of our stock option plans over the years 2015 through 2017 is set out below.

Warrants issued pursuant to a decision in principle of March 16, 2015 for certain employees and consultants

The Extraordinary General Meeting of Shareholders of March 16, 2015 has approved in principle the issuance of maximum of 850,000 warrants for the benefit of certain employees, certain consultants and certain directors of the Company. 442,801 warrants have been granted to and accepted by the relevant beneficiaries and therefore, 442,801 warrants have actually been issued.

The warrants each have an exercise price of €9.98.

The warrants vest over 4 years: 25% of the warrants vest after one year; after that date the remaining 75% become vested on a monthly basis (2.083% per month).

The warrants can only be exercised when vested and, in principle, as from the beginning of the fourth calendar year following the year in which the warrants have been granted (thus from January 1, 2019 through March 15, 2022). In the case of a termination of the employment agreement or the consultant agreement without cause, all vested warrants need to be exercised during the then running exercise period, or the next exercise period if such

termination does not take place during an exercise period. Vested warrants which have not been exercised in such exercise period, cannot be transferred to future exercise periods and will lapse. In the case of a termination of the employment agreement or the consultant agreement for cause, all warrants (whether or not vested) lapse.

All non-vested warrants lapse upon termination of the relevant employment agreement or consultant agreement. The term of the warrants is seven years as of the decision in principle to issue the warrants (i.e. March 16, 2015). Any warrants that have not been exercised within their term become null and void.

Warrants issued pursuant to a decision in principle of September 14, 2015 for certain employees and consultants

The Board Meeting of September 14, 2015 has approved in principle the issuance of maximum 290,000 warrants for the benefit of certain employees and for the benefit of an at time still to be appointed member of the management of the Company. 233,000 warrants have been granted to and accepted by the relevant beneficiaries and therefore 233,000 warrants have actually been issued.

The warrants each have an exercise price as set forth below:

• 150,000 warrants have an exercise price of €12.10; and

• 83,000 warrants have an exercise price of €12.29.

The warrants can only be exercised when vested and, in principle, as from the beginning of the fourth calendar year following the year in which the warrants have been granted (thus from January 1, 2019 through September 13, 2022). In the case of a termination of the employment agreement or the consultant agreement without cause, all vested warrants need to be exercised during the first fifteen days of the quarter in which the end of the employment agreement or, consultant agreement falls, even if such exercise period precedes the beginning of the fourth year following the calendar year in which the date of the grant lies. The tax consequences of such exercise will exclusively be borne by the relevant warrant holder. Vested warrants which have not been exercised in such exercise period cannot be transferred to future exercise periods and will lapse. In the case of a termination of the employment agreement or the consultant agreement for cause, all warrants (whether or not vested) lapse.

All non-vested warrants lapse upon termination of the relevant employment agreement or consultant agreement. The term of the warrants is seven years as of the decision in principle to issue the warrants (i.e. September 14,

2015). Any warrants that have not been exercised within their term become null and void.

Warrants issued pursuant to a decision in principle of February 24, 2016 for certain employees and consultants

The Board Meeting of February 24, 2016 has approved in principle the issuance of maximum 590,000 warrants for the benefit of certain employees and certain members of the management. 429,479 warrants have been granted to and accepted by the relevant beneficiaries and therefore 429,479 warrants been actually issued.

The warrants each have an exercise price of €12.02.

The warrants vest over 3 years: 28% of the warrants vest after one year; after that date the remaining 72% become vested on a quarterly basis (9% per quarter).

The warrants can only be exercised when vested and, in principle, as from the beginning of the fourth calendar year following the year in which the warrants have been granted (thus from January 1, 2020 to February 23, 2023). In the case of a termination of the employment agreement or the consultant agreement without cause, all vested warrants need to be exercised during the first fifteen days of the quarter in which the end of the employment agreement or consultant agreement falls, even if such exercise period precedes the beginning of the fourth year following the calendar year in which the date of the grant lies. The tax consequences of such exercise will exclusively be borne by the relevant warrant holder. Vested warrants which have not been exercised in such exercise period cannot be transferred to future

exercise periods and will lapse. In the case of a termination of the employment agreement or the consultant agreement for cause, all warrants (whether or not vested) lapse. All non-vested warrants lapse upon termination of the relevant employment agreement or consultant agreement. The term of the warrants is seven years as of the decision in principle to issue the warrants (i.e. February 24, 2016). Any warrants that have not been exercised within their term become null and void.

Warrants issued pursuant to a decision in principle of September 9, 2016 for certain employees and consultants

The Board Meeting of September 9, 2016 approved in principle the issuance of maximum 320,000 warrants for the benefit of certain employees and for the benefit of an at time still to be appointed member of the management. None of the warrants which have been granted to the beneficiaries, have been accepted and therefore no warrants have been actually issued under this stock option plan.

Warrants issued pursuant to a decision in principle of February 22, 2017 for certain employees and consultants

The Board Meeting of February 22, 2017 has approved in principle the issuance of maximum 740,000 warrants for the benefit of certain employees and certain members of the management. 527,061 warrants have been granted to and accepted by the relevant beneficiaries and therefore 527,061 warrants been actually issued.

The warrants each have an exercise price of €12.33.

The warrants vest over 3 years: 28% of the warrants vest after one year; after that date the remaining 72% become vested on a quarterly basis (9% per quarter).

The warrants can only be exercised when vested and, in principle, as from the beginning of the fourth calendar year following the year in which the warrants have been granted (thus from January 1, 2021 to February 21, 2024). In the case of a termination of the employment agreement or the consultant agreement without cause, all vested warrants need to be exercised during the first fifteen days of the quarter in which the end of the employment agreement or consultant agreement falls, even if such exercise period precedes the beginning of the fourth year following the calendar year in which the date of the grant lies. The tax consequences of such exercise will exclusively be borne by the relevant warrant holder. Vested warrants which have not been exercised in such exercise period cannot be transferred to future exercise periods and will lapse. In the case of a termination of the employment agreement or the consultant agreement for cause, all warrants (whether or not vested) lapse.

All non-vested warrants lapse upon termination of the relevant employment agreement or consultant agreement. The term of the warrants is seven years as of the decision in principle to issue the warrants (i.e. February 22, 2017). Any warrants that have not been exercised within their term become null and void.

Warrants issued pursuant to a decision in principle of September 20, 2017 for certain employees and consultants

The Board Meeting of September 20, 2017 has approved in principle the issuance of maximum 670,000 warrants for the benefit of certain employees and certain members of the management. 629,000 warrants have been granted to and accepted by the relevant beneficiaries and therefore warrants been actually issued.

The warrants each have an exercise price of €12.26; €12.96; €13.32; €14.53; €17.84; €19.78 and €23.36.

The warrants vest over 3 years: 28% of the warrants vest after one year; after that date the remaining 72% become vested on a quarterly basis (9% per quarter).

The warrants can only be exercised when vested and, in principle, as from the beginning of the fourth calendar year following the year in which the warrants have been granted (thus from January 1, 2021 to September 19, 2024). In the case of a termination of the employment agreement or the consultant agreement without cause, all vested warrants need to be exercised during the first fifteen days of the quarter in which the end of the employment agreement or consultant agreement falls, even if such exercise period precedes the beginning of the fourth year following the calendar year in which the date of the grant lies. The tax consequences of such exercise will exclusively be borne by the relevant warrant holder. Vested warrants which have not been exercised in such exercise period cannot be transferred to future exercise periods and will lapse. In the case of a termination of the employment agreement or the consultant agreement for cause, all warrants (whether or not vested) lapse.

All non-vested warrants lapse upon termination of the relevant employment agreement or consultant agreement. The term of the warrants is seven years as of the decision in principle to issue the warrants (i.e. September 20,

2017). Any warrants that have not been exercised within their term become null and void.

Extension of certain warrant plans

The General Shareholders Meeting of April 30, 2009 and the Board of Directors meeting of June 22, 2009 approved the five-year extension of certain warrant plans in accordance with Art. 583 of the Belgian Companies Code and in accordance with Art. 21 of the “Economische Herstelwet”.

Because of this extension, the fair value of the warrants has changed. The incremental fair value was calculated as the difference between the fair value with and without extension at the date of extension.

Overview of share-based compensation arrangements

		Exercise price		Fair value		Number of warrants		Outstanding warrants at December 31
Warrant plan	Expiry date	(in €)		(in €)		granted		2017		2016
Plan - July 13, 2006	July 12, 2018		2.00		1.26		875,000		210,000		560,000
Plan - December 29, 2006	December 28, 2018		2.80		1.76		67,500		5,000		9,500
Plan - June 14, 2007	June 13, 2019		2.80		1.80		212,500		0		0
Plan - October 12, 2007	October 11, 2017		7.00		3.78		10,713		0		3,517
Plan - Augustus 22, 2008	August 21, 2015		4.88		3.11		75,000		0		0
Plan - Augustus 22, 2008	August 21, 2020		4.88		3.11		300,000		70,417		73,917
Plan - September 29, 2009	September 28, 2016		6.99		5.25		205,400		0		0
Plan - October 30, 2009	October 29, 2016		8.19		5.07		170,000		0		0
Plan - December 3, 2010	December 2, 2017		8.24		4.49		85,500		0		25,250
Plan - April 28, 2011	April 27, 2016/2018		8.68		3.78-4.48		387,050		22,500		72,892
Plan - February 1, 2012	January 31, 2017/2019		3.21		1.38-1.64		748,750		91,950		119,512
Plan - April 26, 2012	April 25, 2017/2019		3.23		1.47-1.74		162,500		0		46,875
Plan - November 6, 2012	November 5, 2017/2019		5.44		2.15-2.89		17,868		0		5,269
Plan - January 29, 2013	January 28, 2019		6.46		3.18-4.04		391,330		186,206		297,744
Plan - August 5, 2013	August 4, 2020		6.79		3.86-4.07		324,840		64,590		258,693
Plan - November 25, 2013	November 24, 2018		7.27		3.86-4.07		50,000		50,000		50,000
Plan - April 24, 2014	April 23, 2019/2021		8.81		3.06-3.80		327,224		287,732		295,469
Plan - March 16, 2015	March 15, 2022		9.98		3.71-3.92		442,801		425,019		439,936
Plan - September 14, 2015	September 13, 2022		12.10/12.29		5.20		233,000		215,500		218,300
Plan - February 24, 2016	February 23, 2023		12.02		4.92		429,479		377,899		416,952
Plan - February 22, 2017	February 21, 2024		12.33		5.11		527,061		499,745		0
Plan - September 20, 2017	September 19, 2024		12.26-14.53		4.77		291,500		291,500		0
Total							6,335,016		2,798,058		2,893,880

The following reconciles the share options outstanding at the beginning and end of the year:

	Number of warrants			Average exercise price (in €)
Outstanding warrants at January 1, 2015		3,015,978			5.71
Granted		525,801			10.34
Forfeited		(67,569	)		7.16
Exercised		(798,215	)		5.90
Expired		(964	)		8.59
Outstanding warrants at December 31, 2015		2,675,031			6.22
Granted		579,479			12.04
Forfeited		(69,742	)		9.45
Exercised		(575,638	)		3.91
Expired		0			0.00
Outstanding warrants at December 31, 2016		2,609,130			7.94
Granted		818,561			12.33
Forfeited		(68,227	)		11.27
Exercised		(654,412	)		0.24
Expired		(4,494	)		12.16
Outstanding warrants at December 31, 2017		2,700,558			11.30

The fair value of the warrants has been determined at grant date based on the Black-Scholes formula. The variables used in this model are:

Warrant plan	Expected dividend yield		Expected stock price volatility			Risk-free interest rate			Expected duration		Fair value (in €)
Plan - July 13,2006		0.00		60.0	%		3.95	%		7.00		0.63
Plan - December 29, 2006		0.00		60.0	%		3.95	%		7.00		0.88
Plan - June 14, 2007		0.00		60.0	%		4.63	%		7.00		0.90
Plan - October 12, 2007		0.00		60.0	%		4.22	%		4.78		3.78
Plan - Augustus 22, 2008		0.00		60.0	%		4.42	%		7.00		3.11
Plan - September 29, 2009		0.00		60.0	%		3.14	%		7.00		5.25
Plan - October 30, 2009		0.00		60.0	%		3.11	%		7.00		5.07
Plan - December 3, 2010		0.00		50.0	%		3.46	%		7.00		4.49
Plan - April 28, 2011		0.00		55.0	%		2.35%-2.84	%		5.00-7.00		1.38-1.64
Plan - February 1, 2012		0.00		55.0	%		2.83%-3.65	%		5.00-7.00		1.47-1.74
Plan - April 26, 2012		0.00		49.0%-56.0	%		1.09%-1.78	%		5.00-7.00		2.15-2.89
Plan - November 6, 2012		0.00		53.4%-54.0	%		1.54%-1.88	%		6.60-7.00		3.18-4.04
Plan - January 29, 2013		0.00		52.7%-53.8	%		1.56%-2.08	%		6.70-7.00		3.86-4.07
Plan - August 5, 2013		0.00		52.7%-53.8	%		1.56%-2.08	%		6.70-7.00		3.86-4.07
Plan - November 25, 2013		0.00		40.9	%		0.91%-1.50	%		5.00-7.00		3.06-3.80
Plan - April 24, 2014		0.00		40.6	%		0.2	%		7.00		3.71-3.92
Plan - March 16, 2015		0.00		40.9	%		0.6	%		7.00		5.20
Plan - September 14, 2015		0.00		40.9	%		0.6	%		7.00		5.20
Plan - February 24, 2016		0.00		42.6	%		0.2	%		7.00		4.92
Plan - February 22, 2017		0.00		39.1	%		0.21	%		7.00		5.11
Plan - September 20, 2017		0.00		37.7	%		0.08	%		7.00		4.77

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Financial Liabilities

12 Months Ended

Dec. 31, 2017

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Financial Liabilities

16 FINANCIAL LIABILITIES

On May 27, 2015, the Company raised €100 million through a private placement of €100 million senior unsecured bonds due May 27, 2020. The bonds were placed through an accelerated book building placement with qualified investors outside the United States, in accordance with Regulation S under the Securities Act. The bonds will mature on May 27, 2020 (5 years), are in dematerialized form in the denomination of €100,000 each, are issued at par and will be redeemed at par at maturity. The bonds pay a coupon of 3.25% per annum, payable semi-annually in arrears on November 27 and May 27 of each year, starting on November 27, 2015. The initial price for the conversion of the bonds into ordinary shares of the issuer is €12.93, representing approximately a 26.5% premium above the reference price of €10.2219, being the VWAP (Volume Weighted Average Price) of the ordinary shares on Euronext Brussels on May 20, 2015. At the initial conversion price, the convertible bonds will be convertible into 7,733,952 fully paid-up ordinary shares of the issuer.

In accordance with Condition 5,(b),(vi) of the terms and conditions of the Bonds, the initial conversion price for the Bonds has been adjusted downwards, following our announcement on October 25, 2017 of the pricing of our initial U.S. public offering totaling approximately $200 million in gross proceeds from the sale of 11,430,000 ordinary shares in the form of ADSs at a public offering price of $17.50 per ADS, before underwriter discounts, and the granting by us to the underwriters of a 30-day option to purchase up to an additional 1,714,500 ordinary shares in the form of ADSs in connection with the offering.

As a consequence, the Calculation Agent has determined that the conversion price of the Bonds is to be adjusted from €12.93 to €12.66 per ordinary share (after rounding in accordance with Condition 5, (f) the terms and conditions of the Bonds). The conversion price adjustment became effective on October 27, 2017. The Bonds are now convertible into an aggregate of 7,896,960 ordinary shares, at a conversion price of €12.66 per ordinary share.

Conversion of the convertible bonds in the Company’s ordinary shares is at the option of the holder. In case of conversion: a cash alternative election (at the option of the issuer) is available including a number of restrictions. As the issuer has the cash alternative election, it has a choice over how the share conversion option will be settled (i.e. net in cash or by exchanging shares for cash). Furthermore, the conversion option includes an adjustment mechanism of the exercise price in case of dilutive transactions, which is a characteristic of a derivative instrument. Therefore, the share conversion option is a derivative at FVTPL according to IAS 39 and not an own equity instrument.

	As at December 31,
€ in thousands	2017		2016		2015
Convertible bond
Host debt		88,715		84,537		80,682
Embedded derivative		66,454		19,812		54,146
Financial liabilities		155,169		104,349		134,828
of which : non-current		155,169		104,349		134,828

Maturity table

The following table details the Company’s remaining contractual maturity of its financial liabilities with agreed repayment periods. The tables have been drawn up based on the undiscounted cash flows of financial liabilities based on the earliest date on which the Company can be required to pay. The tables include both interest and principal cash flows.

	As at December 31,
€ in thousands	2017		2016		2015
Borrowings
Within one year		3,250		3,250		3,250
Between 2 and 5 years		104,875		108,125		111,375
Over 5 years				0		0
Total		108,125		111,375		114,625

BORROWINGS AT FAIR VALUE
Closing Balance at December 31, 2016	104,349
Financing cash flows	(3,250	)
Payment of interests	(3,250	)
Non-cash changes	54.070
Effective Intrest Rate	7,427
Changes in fair value of derivative	46,642
Closing Balance year ended December 31, 2017	155,169

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TRADE AND OTHER PAYABLES

12 Months Ended

Dec. 31, 2017

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TRADE AND OTHER PAYABLES

17 TRADE AND OTHER PAYABLES

	As at December 31,
€ in thousands	2017		2016		2015
Trade payables		4,761		5,519		4,263
Accruals for invoices to be received		10,804		14,800		7,393
Total trade payables		15,565		20,319		11,656
Social security		852		753		561
Payroll payables		5,705		4,654		4,194
Other liabilities		5		12		1
Total other payables		6,562		5,419		4,756
Total trade and other payables		22,127		25,738		16,412

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DEFERRED INCOME

12 Months Ended

Dec. 31, 2017

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DEFERRED INCOME

18 DEFERRED INCOME

Deferred income mainly relates to cash received from research collaboration agreements prior to completion of the earnings process.

	As at December 31,
€ in thousands	2017		2016		2015
Within 1 year		21,905		22,118		55,738
In the second to the fifth year		10,791		11,504		30,385
Total deferred income*		32,696		33,622		86,123

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DEFERRED TAXES

12 Months Ended

Dec. 31, 2017

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DEFERRED TAXES

19 DEFERRED TAXES

The below table summarizes the sources of deferred taxes:

The Company has unused tax losses carry forward, without expiry date. This, combined with the other temporary differences, results in a net unrecognized deferred tax asset position.

The corporate income tax rate has decreased from 33.99% to 29.58% as from fiscal year 2019 (income year 2018). The deferred tax position as at December 31, 2017 has been calculated with the decreased tax rate.

The Company has accounted for a total research and development incentives receivable of €24.5 million as at December 31, 2017 (€19.5 million as at December 31, 2016 and €15.8 million as at December 31, 2015) following an research and development incentive scheme in Belgium under which the tax incentive can be refunded after five years if not offset against taxable basis over that period. The research and development incentives are recorded net against the relating research and development expenses in the statement of comprehensive income. We expect to receive this amount progressively over 6 years.

Due to the uncertainty surrounding the Company’s ability to realize taxable profits in the near future, the Company did not recognize any deferred tax assets.

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Revenue

12 Months Ended

Dec. 31, 2017

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Revenue

20 REVENUE

	Year ended December 31,
€ in thousands	2017		2016		2015
Upfront fees		24,752		52,311		58,559
Research and development service fees		13,255		13,875		14,403
Milestone payments		17,500		18,400		3,500
License fees & other revenue		55		187		299
Total		55,562		84,773		76,761

AbbVie

In September 2013, the Company and AbbVie entered into a global licensing agreement worth up to US$840 million plus double-digit royalties, relating to the development and commercialization of vobarilizumab in RA and systemic lupus erythematosus (SLE). As part of the agreement, the Company received US$175 million in an up-front payment and assumed responsibility for the execution of Phase II clinical development in both RA and SLE. In return, AbbVie received certain rights to opt-in and license vobarilizumab (including, following such opt-in, further responsibility for Phase III development, registration and commercialization).

In March 2018, we reported top line results from our Phase II trial of vobarilizumab in patients with SLE. AbbVie has again the right to opt-in and license vobarilizumab.

Merck & Co.

On October 2, 2012, the Company announced a collaboration with a subsidiary of Merck & Co., Inc. known outside the US and Canada as MSD, to develop and commercialize Nanobody candidates directed towards a voltage gated ion channel with the option to develop and commercialize a Nanobody to a second target. Under the terms of the agreement, Merck gains exclusive global rights to Nanobodies against the selected target, with an option for similar rights to a second target. Upon signing, Merck paid the Company a €6.5 million upfront payment and a €2 million fee for research funding. In addition, the Company will be eligible to receive up to

€429 million in research, regulatory and commercial milestone payments associated with the progress of multiple candidates as well as tiered royalties on any products derived from the collaboration. The Company will be responsible for the discovery of Nanobody candidates and Merck will be responsible for the research, development, manufacturing and commercialization of any Nanobody product resulting from the collaboration.

In March 2015, the Company announced an extension of this collaboration to the end of September 2016. On October 12, 2016, the Company announced a second extension to September 2018 which triggered a €1 million milestone payment.

On February 3, 2014, the Company announced that it had entered into a second research collaboration and licensing agreement with a subsidiary of Merck & Co., Inc. This new exclusive collaboration and licensing agreement is focused on the discovery and development of several predefined Nanobody candidates (including bi- and tri-specifics) directed toward so called ‘immune checkpoint modulators’, proteins believed to be potential targets for the development of cancer immunotherapies, a rapidly emerging approach to the treatment of a wide range of cancer types. Under the terms of the agreement, the Company has received an upfront payment of €20 million and is eligible to receive up to €10.7 million in research funding during the initial three-year research term of the collaboration. In addition, the Company is eligible to receive development, regulatory and commercial milestone payments on achieved sales thresholds for a number of products with ultimate potential to accrue as much as €1.7 billion plus tiered royalties. Merck will be responsible for the development, manufacturing and commercialization of any products resulting from the collaboration.

On July 22, 2015, the Company announced an expansion of this immuno-oncology collaboration with the subsidiary of Merck & Co., Inc. to address an increased number of immune checkpoint modulator targets. As part of this expansion agreement, the Company will be responsible for the discovery and development of up to 12 additional Nanobody programs against individual protein targets and target combinations (mono- specific and multi-specific Nanobodies) through to the in vivo pre-clinical proof-of-concept stage, after which Merck will have the option to advance specified lead candidates. Under the terms of this four-year expansion, the Company received a €13 million upfront payment comprising exclusivity fees and FTE payments and is eligible to receive further research funding over the term of the collaboration. In addition, the Company will be eligible to receive additional exclusivity fees, depending on the number of programs for which Merck decides to exercise its licensing option, plus development, regulatory and commercial milestone payments of up to €338.5 million per program, as well as tiered royalties on annual net sales upon commercialization of any Nanobody products. Merck will be responsible for clinical development, manufacturing and commercialization of any products resulting from the collaboration.

Boehringer Ingelheim

On September 7, 2007, Boehringer Ingelheim and the Company announced a major Global Strategic Alliance to discover, develop and commercialize up to 10 different Nanobody programs. In return, the Company was entitled to receive an upfront payment and received research license payments, milestones and royalties. Additionally, Boehringer Ingelheim subscribed for €15 million in the Company’s IPO on Euronext Brussels in November 2007. The Company has certain co-promotion rights in Europe. The agreement was extended a last time until December 31, 2014, being the end of the Discovery Term of this Agreement.

In November 2015, Boehringer Ingelheim presented compelling pre-clinical proof-of-concept data with the bi-specific anti-VEGF/Ang2 Nanobody in multiple in vivo cancer models. A Phase I dose escalation study with the half-life extended bi-specific anti-VEGF/Ang2 Nanobody in adult patients with advanced solid tumors was initiated by Boehringer Ingelheim on January 29, 2016, triggering a €8 million milestone payment to the Company. The aim of the study is to evaluate the safety profile and dosing schedule for this Nanobody.

On April 21, 2016, the Company and Boehringer Ingelheim announced the initiation of a Phase I study to evaluate the safety, tolerability and pharmacokinetics of single ascending doses of an anti-CX3CR1 Nanobody, administered intravenously. The start of the study triggered a €8 million milestone payment to the Company. This novel Nanobody blocks the function of the G-protein coupled receptor (GPCR), CX3CR1, a protein that has proven to be difficult to address with conventional antibodies. By blocking the function of CX3CR1, the activity of inflammatory immune cells, which play a major role in chronic kidney disease, may be inhibited.

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Grant Income

12 Months Ended

Dec. 31, 2017

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Grant Income

21 GRANT INCOME

€ in thousands	Amount granted		Received at December 31,						Still to receive at December 31,						Recognised as grant income for the years ended December 31,
			2017		2016		2015		2017		2016		2015		2017			2016		2015
IWT 18		886		886		886		708		0		0		178		0			178		0
IWT 19		1,113		1,113		1,674		1,116		0		420		978		(76	)		120		484
IWT 20		445		445		356		267		0		89		178		89			89		75
IWT 21		243		243		368		276		0		92		184		(44	)		27		220
Total		2,687		2,687		3,284		2,367		0		601		1,518		(31	)		414		779

The Company received several grants to support various research programs from an agency of the Flemish government to support technological innovation in Flanders (‘IWT’ – Agency for Innovation and Entrepreneurship). These grants carry clauses which require the Company to maintain a presence in the Flemish region for a number of years and invest according to pre-agreed budgets. The amounts still to receive mentioned in the table above are not recognized as receivables in the statement of financial position as there are conditions attached which are not yet met.

The Company received a fixed percentage of the expenses incurred in the following research and development projects:

IWT 18: T-cell recruiting Nanobodies for targeted delivery

Grantor:		IWT
Start date:		June 1, 2013
End date:		May 31, 2015
Amount granted:	€	885,597
Amount recognized:	€	885,597
Amount received:	€	885,597

IWT 19: Development of a novel Nanobody-based therapeutic platform for treatment of ocular diseases

Grantor:		IWT
Start date:		April 1, 2014
End date:		March 31, 2017
Amount granted:	€	1,112,926
Amount recognized:	€	1,112,926
Amount received:	€	1,112,926

IWT 20: Bispecific Nanobodies with enhanced specificity

Grantor:		IWT
Start date:		June 1, 2014
End date:		May 31, 2016
Amount granted:	€	445,027
Amount recognized:	€	445,027
Amount received:	€	445,027

IWT 21: Development of Nanobody-based immunotoxins

Grantor:		IWT
Start date:		June 1, 2014
End date:		May 31, 2016
Amount granted:	€	243,489
Amount recognized:	€	243,489
Amount received:	€	243,489

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RESEARCH AND DEVELOPMENT EXPENSES

12 Months Ended

Dec. 31, 2017

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RESEARCH AND DEVELOPMENT EXPENSES

22 RESEARCH AND DEVELOPMENT EXPENSES

	Year ended December 31,
€ in thousands	2017			2016			2015
Consumables		5,821			5,916			4,448
Outsourcing		52,655			65,925			53,897
Patent costs		2,868			2,134			2,177
Employee expenses		30,426			26,707			22,799
Share-based compensation expense		867			808			751
Other operating expenses		6,746			5,825			5,281
Reduction withholding tax for scientists		(4,119	)		(3,702	)		(3,381	)
Research and development incentives		(6,916	)		(5,078	)		(3,873	)
Subtotal		88,348			98,535			82,099
Depreciation and amortization expenses		2,573			1,780			985
Total research and development expenses		90,920			100,315			83,084

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GENERAL AND ADMINISTRATIVE EXPENSES

12 Months Ended

Dec. 31, 2017

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GENERAL AND ADMINISTRATIVE EXPENSES

23 GENERAL AND ADMINISTRATIVE EXPENSES

	Year ended December 31,
€ in thousands	2017			2016			2015
Employee benefit expenses		4,217			3,588			3,092
Share-based compensation expense		1,739			1,764			1,069
Executive Committee compensation(1)		3,787			3,406			3,341
Consultancy		5,904			2,414			1,870
Other operating expenses		2,859			2,055			1,887
Reduction withholding tax for scientists		(162	)		(220	)		(204	)
Subtotal		18,344			13,007			11,055
Depreciation and amortization expenses		461			465			356
Total general and administrative expenses		18,805			13,472			11,411

1 The Executive Committee consists of key management members and entities controlled by them.

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EMPLOYEE BENEFITS EXPENSES

12 Months Ended

Dec. 31, 2017

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EMPLOYEE BENEFITS EXPENSES

24 EMPLOYEE BENEFITS EXPENSES

	Years ended December 31,
€ in thousands	2017			2016			2015
Salaries, wages and bonuses		24,416			20,986			18,233
Social security		6,336			5,730			4,779
Post-employment benefits		1,839			1,026			881
Share-based compensation expense		2,606			2,572			1,820
Other employment costs		2,089			2,548			1,997
Executive Committee compensation1		3,750			3,406			3,341
Reduction withholding tax for scientists		(4,282	)		(3,922	)		(3,585	)
Total		36,755			32,346			27,466
Average full-time equivalents (FTE)
Executive committee(1)		7			7			8
R&D personnel		363			321			284
General and administrative staff		49			36			33
Average FTE		419			364			325

(1) The Executive Committee consists of key management members and the entities controlled by them.

The Company offers several post-employment, death, disability and healthcare benefit schemes. All employees have access to these schemes. The death, disability and healthcare benefits granted to employees of the Company are covered by external insurance companies, where premiums are paid annually and charged to the income statement as they were incurred.

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OPERATING LEASES

12 Months Ended

Dec. 31, 2017

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OPERATING LEASES

25 OPERATING LEASES

Operating leases relate to leases of company cars (lease term of 4 years) and office facilities (lease term of 5 years). The Company does not have an option to purchase the leased assets at the expiry of the lease periods. For the year ended December 31, 2017, minimum lease payments for a total amount of €3,681 thousand have been recognized in the statement of comprehensive income (2016: €3,487 thousand; 2015: €3,310 thousand).

The following table presents the non-cancellable operating lease commitments:

	Years ended December 31,
€ in thousands	2017		2016		2015
Within 1 year		3,902		3,853		3,277
In the second to the fifth year		9,557		12,598		4,750
After five years		0		0		0

In 2016, the Company and Bio-Versneller NV ended the existing service agreement and negotiated a new agreement commencing October 1, 2016. The new service agreement provides the Company with 8,800 m2 of laboratory and office facilities. After an initial fixed period of three years, both parties will be entitled to terminate the agreement with a notice period of minimum two years.

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FINANCIAL INCOME AND EXPENSES

12 Months Ended

Dec. 31, 2017

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FINANCIAL INCOME AND EXPENSES

26 FINANCIAL INCOME AND EXPENSES

	Years ended December 31,
€ in thousands	2017			2016			2015
Financial income
Interest income on financial assets		49			298			1,101
Financial income related to convertible bond
Changes in fair value of embedded derivative					34,334
Other financial income		400			129			667
Total		449			34,761			1,768
Financial expenses
Interest charges on financial liabilities
Financial expenses related to convertible bond
Changes in fair value of embedded derivative		(46,642	)					(34,646	)
Interest expenses on convertible bond		(7,427	)		(7,105	)		(4,074	)
Financing charges								(549	)
Other financial expenses		(717	)		(143	)		(91	)
Total		(54,786	)		(7,248	)		(39,360	)
Net financial result		(54,337	)		27,513			(37,592	)

In 2017, the line ‘Financial income related to convertible bond’ consists of the change in fair value of the embedded derivative as a result of the higher share price at year-end compared to the share price at the end of 2016.

Interest expenses on convertible bond includes the interest coupon of the host debt component of the convertible bond and the amortization of the difference between the initial carrying value of that host debt and its redemption amount.

In 2017, other financial expenses includes unrealized foreign exchange losses of €19 thousand (2016: €50 thousand) and realized foreign exchange losses of €331 thousands (2016: €92 thousand).

In 2017, other financial income includes realized foreign exchange gains of €373 thousand (2016: €164 thousand), there were no unrealized foreign exchange gains (2016: €0).

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INCOME TAX EXPENSES

12 Months Ended

Dec. 31, 2017

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INCOME TAX EXPENSES

27 INCOME TAX EXPENSES

	Years ended December 31,
€ in thousands	2017			2016			2015
Loss of the year		(108,532	)		(1,087	)		(54,547	)
Income taxes calculated at 33.99%		36,890			369			18,541
Effect of income that is exempt from taxation		368			490			558
Effect of expenses that are not deductible in determining taxable profit		(248	)		(219	)		(199	)
Effect of unused tax losses and tax offsets not recognised as deferred tax assets		(37,010	)		(641	)		(18,899	)
Effective income taxes		(0	)		(0	)		0

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LOSS PER SHARE

12 Months Ended

Dec. 31, 2017

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LOSS PER SHARE

28 LOSS PER SHARE

Earnings/losses per share are calculated by dividing the net result attributable to equity holders by the weighted average numbers of shares during the year.

	Years ended December 31,
	2017			2016*			2015
Basic gain/(loss) per share (in €)		(1.74	)		(0.02	)		(1.00	)
Diluted gain/(loss) per share (in €)		(1.74	)		(0.43	)		(1.00	)
	Years ended December 31,
Basic loss per share	2017			2016*			2015
Loss of the year (In thousands of €)		(108,532	)		(1,087	)		(54,547	)
Weighted average number of shares outstanding		62,322,875			58,499,545			54,382,147
Basic loss per share (in €)		(1.74	)		(0.02	)		(1.00	)
Diluted loss per share	2017			2016			2015
Loss of the year as used for basic loss per share (In thousands of €)		(108,532	)		(1,087	)		(54,547	)
Adjustments to earnings relating to convertible bond		0			(27,229	)		0
Loss of the year (In thousands of €) for diluted earnings per share		(108,532	)		(28,316	)		(54,547	)
Weighted average number of shares outstanding		62,322,875			58,499,545			54,382,147
Adjustments to number of shares relating to convertible bond		0			7,733,952			0
Weighted average number of shares outstanding after dilution effect		62,322,875			66,233,497			54,382,147
Diluted loss per share (in €)		(1.74	)		(0.43	)		(1.00	)

As the Company is incurring operating losses, warrants have an anti-dilutive effect. As a result, warrants have not been taken into account for purpose of the diluted loss per share calculation.

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CONTINGENCIES AND ARBITRATIONS

12 Months Ended

Dec. 31, 2017

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CONTINGENCIES AND ARBITRATIONS

29 CONTINGENCIES AND ARBITRATIONS

At present, there are no contingencies and arbitrations.

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Commitments Lease agreements

12 Months Ended

Dec. 31, 2017

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Commitments Lease agreements

30 COMMITMENTS Lease agreements

The Company has signed contracts with Bio-Versneller NV, who has provided the Company with 8,000 m² of laboratory and office facilities within the Technologiepark since June 2010. The initial term of the contract was an extendable period of eight years.

Bio-Versneller NV was granted a pledge of €1.7 million in the framework of additional investments which it made in the Bio-Accelerator building at the request of the Company. The pledge has been reduced every year over a period of five years as from January 2012 and as at December 31, 2016 the outstanding amount was reduced to 0 euro.

In 2016, the Company and Bio-Versneller NV ended the existing service agreement and negotiated a new agreement starting from October 1, 2016. The new service agreement provides the Company with 8,800 m² of laboratory and office facilities. After an initial fixed period of three years both parties will be entitled to terminate the agreement with a notice period of minimum two years.

The Company was granted by KBC Bank NV a credit commitment of €1.6 million for the guarantee clause, which is mentioned in the contract.

The Company has also signed a contract with Devgen nv, who has provided the Company with 970.68 m² of laboratory facilities within the Technologiepark 30 as from May 2016, with an initial term of five years which can be extended.

In 2017, the Company also extended its lease agreement with Incubatie- en Innovatiecentrum Universiteit Gent NV, or IIC UGent, for a storage space of 42 square meters also in Ghent/Zwijnaarde, Belgium. This lease agreement is for a period of three years, commencing on March 1, 2017.

The Company further owns 25,322 m² of land on which the Company developed facilities for the housing of llamas.

Purchase commitments

The Company has entered into numerous agreements with universities, medical centers and external researchers for research and development work and for the validation of the Company’s technology and products. These agreements typically have durations of one to three years. The Company must pay fixed and variable fees to the collaborators and in exchange receives access and rights to the result of the work. The total commitment amounts to €75.9 million, of which €33.2 million is expected to be fulfilled within one year and the remainder between two to five years.

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Related Party Transactions

12 Months Ended

Dec. 31, 2017

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Related Party Transactions

31 RELATED PARTY TRANSACTIONS

Remuneration key management and non-executive directors

Key management consists of the members of the Executive Committee and the non-executive Directors and the entities controlled by any of them.

	Years ended December 31,
€ in thousands, except for number of management members	2017			2016			2015
Number of management members		7			7			8
Short-term employee benefits (salaries, social security, bonuses, lunch vouchers)		2,580			2,394			2,295
Post-employment benefits (group insurance)		284			183			166
Share-based compensation expense		1,512			1,547			834
Other employee benefits		129			130			124
Management fees		398			338			451
Retribution		(27	)		(32	)		(31	)
Total		4,875			4,560			3,839
Number of warrants granted (in units)		433,440			365,844			293,311
Cumulative outstanding warrants (in units)		1,507,149			1,824,259			1,744,645
Shares owned (in units)		577,805			402,805			205,805

Transactions with non-executive Directors:

	Years ended December 31,
€ in thousands	2017		2016		2015
Share-based compensation expense		1		13		41
Management fees		360		363		305
Total		361		376		346
Number of warrants offered or granted (in units)
Cumulative outstanding warrants (in units)		64,590		68,430		74,595
Non-vested warrants				2,432		22,831
Shares owned (in units)		31,434		31,165		25,000

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Events After The Reporting Date

12 Months Ended

Dec. 31, 2017

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Events After The Reporting Date

32 EVENTS AFTER THE REPORTING DATE

In January 2018, the Company announced the appointment of Robert Friesen, PhD, as Chief Scientific Officer, effective March 1, 2018. Dr. Friesen will lead the Company’s scientific, research and technology activities and become a member of the Executive Committee.

On January 28, 2018, the Company entered into a Heads of Agreement, or the Agreement, with Sanofi, a French societe anonyme. Pursuant to the Agreement, Sanofi will offer to acquire all of the Company’s outstanding ordinary shares, including shares represented by American Depositary Shares, warrants and our convertible bonds, at a price per share of €45 in cash, which represents an aggregate equity value of approximately €3.9 billion. The transaction was unanimously approved by the Company’s board of directors and the board of directors of Sanofi. Subject to the satisfaction or waiver of customary closing conditions, the transaction is expected to close by the end of the second quarter 2018.

In January and February 2018, the Company announced changes to its Board of Directors with the departures of Dr. Peter Fellner and Dr. Bo Jesper Hansen, respectively. Dr. Russell G. Greig, who has been a non-executive Director of the Company since 2012, is now the new Chairman of the Board.

On February 16, 2018, the Company announced that as part of the research collaboration signed in July 2017, Sanofi has exercised its options for two additional multi-specific Nanobody product candidates, triggering the payment to the Company of €13 million in exercise fees.

On March 1, 2018, Piet Houwen joined the Company as Chief Operating Officer. Mr. Houwen will be responsible for the support of the Company’s business and R&D processes and become a member of the Executive Committee.

On March 2, 2018, the Company announced that the first patient has been dosed in the Japanese Phase II study of ALX-0171 to treat respiratory syncytial virus (RSV) infections. The study is expected to read out in the second half of 2019.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

12 Months Ended

Dec. 31, 2017

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Foreign currency translation

Foreign currency translation

Functional and presentation currency

The financial statements are presented in euro, which is the Company’s functional and presentation currency.

Transactions and balances

Transactions in foreign currencies are translated at the exchange rates prevailing at the dates of the transactions, and foreign exchange differences arising on translation are recognized in the statement of comprehensive income. Monetary assets and liabilities denominated in foreign currencies are translated at the exchange rate prevailing at the reporting date, and foreign exchange differences arising on translation are recognized in profit or loss and other comprehensive income. Non-monetary assets and liabilities denominated in foreign currencies are translated at the foreign exchange rate ruling at the date of the transaction.

The following foreign exchange rates have been used for the preparation of the accounts:

	Closing rate						Average rate
€1 = x foreign currency	2017		2016		2015		2017		2016		2015
US Dollar		1.1999		1.0522		1.0866		1.1271		1.1059		1.1135
GB Pound		0.8886		0.8533		0.7360		0.8724		0.8131		0.7267

Revenue recognition

Revenue recognition

The Company generates revenue from research collaborations and government grants.

Revenue is recognized when it is probable that future economic benefits will flow to the Company and these benefits can be measured reliably. Further, revenue recognition requires that all significant risks and rewards of ownership of the goods included in the transaction have been transferred to the buyer or when the related services are performed and specific criteria have been met for each of the Company’s activities as described below.

Collaboration and alliance agreements with the Company’s commercial partners for research and development activities typically contain license fees, non-refundable upfront access fees, research and development service fees and milestone payments. Deferred income represents amounts received prior to revenue being earned.

Collaborations

Upfront fees

Non-refundable upfront fees for access to prior research results and databases are recognized when earned, if the Company has no continuing performance obligations and all conditions and obligations are fulfilled (after the delivery of the required information). If the Company has continuing performance obligations towards the client (continuing involvement), the upfront fee received is deferred and recognized over the estimated period of involvement or based on the costs incurred under the related project. Periodically the Company reassesses the estimated time and cost to complete the project phase and adjusts the period over which the revenue is deferred accordingly.

Research and development service fees

Research and development service fees are recognized as revenue over the life of the research agreement as the required services are provided and costs are incurred. These services are usually in the form of a defined number of full-time equivalents of employees (FTE) at a specified rate per FTE.

Commercial collaborations resulting in a reimbursement of research and development costs are recognized as revenue as the related costs are incurred. The corresponding research and development expenses are included in research and development expenses in the financial statements.

Milestone payments

Revenue associated with performance milestones is recognized based upon the achievement of the milestone event if the event is substantive, objectively determinable and represents an important point in the development life cycle of the product candidate.

License fees and royalties

License fees are recognized when the Company has fulfilled all conditions and obligations. The license fee will not be recognized if the amount cannot be reasonably estimated and if the payment is doubtful. As the Company has a continuing involvement during the license period, license fees are recognized evenly over the term of the agreement.

Royalty revenues are recognized when the Company can reliably estimate such amounts and collectability is reasonably assured. As such, the Company generally recognizes royalty revenues in the period in which the licensees are reporting the royalties to the Company through royalty reports. Under this accounting policy, the royalty revenues the Company reports are not based upon the Company’s estimates and such royalty revenues are typically reported in the same period in which the Company receives payment from its licensees.

Government grants

Because it carries out research and development activities, the Company benefits from various grants and research and development incentives from certain governmental agencies. These grants and research and development incentives generally aim to partly reimburse approved expenditures incurred in research and development efforts of the Company.

The Company recognizes a government grant only when there is reasonable assurance that the Company will comply with the conditions attached to the grant and the grant will be received. As such, a receivable is recognized in the statement of financial position and measured in accordance with the related accounting policy mentioned below.

Government grants are recognized in profit or loss on a systematic basis over the periods in which the Company recognizes as expenses the related costs which the grants are intended to compensate. As a result, grants relating to costs that are recognized as intangible assets or property, plant and equipment (grants related to assets or investment grants) are deducted from the carrying amount of the related assets and recognized in the profit or loss statement consistently with the amortization or depreciation expense of the related assets. Grants that intend to compensate costs are released as income when the subsidized costs are incurred, which is the case for grants relating to research and development costs.

Government grants that become receivable as compensation for expenses or losses already incurred are recognized in profit or loss of the period in which they become receivable.

The portion of grants not yet released as income is presented as deferred income in the statement of financial position. In the statement of comprehensive income, government grants are presented as grant income.

Research and development incentives receivables

Non-current research and development incentives receivables are discounted over the period until maturity date according to the appropriate discount rates.

Intangible assets

Intangible assets

Internally generated intangible assets

Research expenses are charged to the statement of comprehensive income as incurred. Development costs are only capitalized if the following conditions are met:

• the technical feasibility of completing the intangible asset;

• the intention to complete the intangible asset and use or sell it;

• the generation of probable future economic benefits;

• the availability of adequate technical, financial and other resources to complete the development and to use or sell the intangible asset; and

• its ability to measure reliably the expenditure attributable to the intangible asset during its development.

At present, the current stage of research activities does not allow any capitalization of intangible assets. The existing regulatory and clinical risks constitute an important uncertainty with respect to the capitalization of development costs. The research and development expenses are not capitalized, as long as the criteria under IFRS are not met.

As no internally generated assets are recognized, all costs with respect to the protection of intellectual property are expensed as research and development expenses.

Purchased intangible assets

Acquired computer software licenses are capitalized based on the costs incurred to acquire and bring to use the specific software. These costs are amortized on a straight-line basis over their estimated useful lives of maximum three years.

Acquired knowledge in the form of licenses and patents is recorded at cost less accumulated amortization and impairment. It is amortized on a straight-line basis over the shorter of the term of the license agreement and its estimated useful life.

The Company does not have intangible fixed assets with an indefinite useful life.

Property, plant and equipment

Property, plant and equipment

An item of property, plant and equipment is carried at historical cost less accumulated depreciation and impairment. Costs relating to the day-to-day servicing of the item are recognized in the income statement as incurred.

A pro rata straight-line depreciation method is used to reflect the pattern in which the asset’s future economic benefits are expected to be consumed by the entity. However, land is not depreciated. The residual value and the useful life of an asset is reviewed each financial year-end for possible impairment.

Depreciation is charged to the income statement on the following basis:

•   Buildings	10 years
•   Equipment	3 years
•   Hardware	3 years
•   Furniture	5 years
•   Equipment under leasing	The shorter of the useful life or the minimum leasing term
•   Leasehold improvements	The shorter of the useful life or the minimum leasing term

Impairment of non-financial assets

Impairment of non-financial assets

Assets that have an indefinite useful life are not subject to amortization and are tested annually for impairment. Assets that are subject to amortization or depreciation are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount may not be recoverable. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset’s fair value less costs to sell and value in use.

Assets other than goodwill that suffered impairment are reviewed for possible reversal of the impairment at each reporting date.

Leases

Leases

Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards incident to ownership of an asset. All other leases are classified as operating leases. Classification is made at the inception of the lease.

Assets held under finance leases by the Company are recognized as assets at their fair value or, if lower, at the present value of the minimum lease payments, using the interest rate implicit in the lease as the discount rate. The corresponding liability is included in the statement of financial position as a finance lease obligation. Assets

held under finance leases are depreciated over their estimated useful life on a systematic basis consistent with the depreciation policy for depreciable assets that are owned by the Company or, if shorter, over the lease term.

Lease payments are apportioned between finance expenses and the reduction of the lease obligation.

Initially incurred costs, directly attributable to the arrangement of the finance lease, are added to the amount recognized as an asset.

Assets held by the Company under operating leases are not recognized in the statement of financial position. Operating lease payments are recognized as expenses in the period in which they are incurred on a straight-line basis over the lease term.

Financial assets

Financial assets

Financial assets are classified into the following specified categories: financial assets “at fair value through profit or loss” (FVTPL), “held-to-maturity” investments, “available-for-sale” (AFS) financial assets and “loans and receivables”. The classification depends on the nature and purpose of the financial assets and is determined at the time of initial recognition and reviewed at each reporting date.

At this moment, the Company only has financial assets classified as “loans and receivables”, which includes trade receivables.

Purchase and sale of financial assets are recognized on the settlement date, which is the date an asset is delivered to or by the Company. The cost of financial assets includes transaction costs.

Loans and receivables are non-derivative financial assets with fixed or determinable payments that are not quoted in an active market. Loans and receivables (including trade and other receivables, bank balances and cash) are measured at amortized cost using the effective interest method, less any impairment.

The effective interest method is a method of calculating the amortized cost of a debt instrument and of allocating interest income over the relevant period. The effective interest rate is the rate that exactly discounts estimated future cash receipts (including all fees and points paid or received that form an integral part of the effective interest rate, transaction costs and other premiums or discounts) through the expected life of the debt instrument, or, where appropriate, a shorter period, to the net carrying amount on initial recognition.

Financial assets are assessed for indicators of impairment at the end of each reporting period. Financial assets are considered to be impaired when there is objective evidence that, as a result of one or more events that occurred after the initial recognition of the financial asset, the estimated future cash flows of the investment have been affected.

For financial assets measured at amortized cost, if, in a subsequent period, the amount of the impairment loss decreases and the decrease can be related objectively to an event occurring after the impairment was recognized, the previously recognized impairment loss is reversed through profit or loss to the extent that the carrying amount of the investment at the date the impairment is reversed does not exceed what the amortized cost would have been had the impairment not been recognized.

Cash and cash equivalents

Cash and cash equivalents

Cash and cash equivalents consists of cash, deposits held at call with banks and short-term deposits with an initial maturity not exceeding one month.

Equity instruments

Equity instruments

Equity instruments issued by the Company are recorded at the proceeds received, net of direct issue costs.

Where the Company purchases the Company’s equity share capital (treasury shares), the consideration paid, including any directly attributable incremental costs (net of income taxes) is deducted from equity attributable to the Company’s equity holders until the shares are cancelled, reissued or disposed of. Where such shares are subsequently sold or reissued, any consideration received, net of any directly attributable incremental transaction costs and the related income tax effects is included in equity attributable to the Company’s equity holders.

Financial liabilities

Financial liabilities

Convertible bond

The Company’s convertible senior notes due 2020 (the convertible bond) are accounted for in accordance with IAS 39 Financial Instruments: Recognition and Measurement and IAS 32 Financial Instruments: Presentation. Since the Company has a cash alternative election, it has a choice over how the share conversion option will be settled (net in cash or by exchanging shares for cash). Therefore, the share conversion option is a derivative at FVTPL according to IAS 39, and not an own equity instrument. As such, the convertible bond consists of a host debt instrument and an embedded share conversion option.

The value assigned to the host debt instrument is the estimated fair value, as of the issuance date. Subsequent to initial recognition, the debt instrument will be measured at amortized cost, using the effective interest rate method.

The embedded derivative was measured initially at fair value (estimated as the difference between the fair value of the total convertible bond and the fair value of the host debt) and subsequently at FVTPL.

The Company has no other derivative financial instruments.

Trade payables

Trade payables

Trade payables within one year are measured at amortized cost ( i.e., at the net present value of the payable amount). Unless the impact of discounting is material, the nominal value is considered.

Provisions

Provisions

A provision is recognized when the Company has a present obligation (legal or constructive) as a result of past events, it is probable (more likely than not) that a transfer of economic benefits will be required to settle the obligation, and a reliable estimate can be made of the amount of the obligation.

The amount recognized as a provision is the best estimate of the consideration required to settle the present obligation at the end of the reporting period. When the impact is likely to be material (for long-term provisions), the amount recognized as a provision is estimated on a net present value basis (discount factor). The increase in provision due to the passage of time is recognized as an interest expense.

A present obligation arises from an obligating event and may take the form of either a legal obligation or a constructive obligation (a constructive obligation exists when the Company has an established pattern of past practice that indicates to other parties that it will accept certain responsibilities and as a result has created a valid expectation on the part of those other parties that it will discharge those responsibilities). An obligating event leaves the Company no realistic alternative to settling the obligation, independently of its future actions.

Employee benefits

Employee benefits

The Company offers several post-employment, death, disability and healthcare benefit schemes. All employees have access to these schemes. The death, disability and healthcare benefits granted to employees of the Company are covered by external insurance companies, where premiums are paid annually and charged to the income statement as they were incurred.

The post-employment pension plans granted to employees of the Company are based on defined contributions for which the insurance company guarantees a defined interest until retirement (type ‘branche 21/tak21’).

As a consequence of the law of December 1, 2015, minimum returns are guaranteed by the employer as follows:

• for the contributions paid as from January 1, 2016, a new variable minimum return based on OLO rates, with a minimum of 1.75% and a maximum of 3.75%. In view of the low rates of the OLO in the last years, the return has been initially set to 1.75%;

• for the contributions paid until end December 2015, the previously applicable legal returns (3.25% and 3.75% respectively on the employer and employee contributions) continue to apply until retirement date of the participants.

In view of the minimum returns guarantees, those plans qualify as Defined Benefit plans.

A provision has to be recognized for the sum of the positive differences, per plan participant, between the minimum guaranteed reserves and the accumulated reserves.

Income taxes

Income taxes

Income tax expense represents the sum of the tax currently payable and deferred tax.

In compliance with IAS 12 Income Taxes, current and deferred taxes are recognized in the statement of profit or loss, other comprehensive income or directly in equity consistently with the accounting for the underlying transaction.

The current tax expense (income) is the estimated amount of tax due on the taxable income for the period, calculated using the tax rates enacted at reporting date.

Deferred taxes result from temporary differences between the carrying amount of assets and liabilities and their tax basis. No deferred taxes are recognized for temporary differences generated by the initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit nor loss. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted by the reporting date and are expected to apply when the related deferred tax asset is realized or the deferred tax liability is settled.

Deferred tax assets are recognized to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. As such, a deferred tax asset for the carry forward of unused tax losses will be recognized to the extent that it is probable that future taxable profit will be available.

Share-based compensation transactions

Share-based compensation transactions

The Company has offered equity-settled, share-based compensation plans to its employees, executive management and consultants. The cost with respect to the employee services received in compensation for the grant of these warrants is recognized as an expense.

The total amount of the expense is recognized over the vesting period and determined based on the fair value of the warrants at grant date. The fair value of each warrant is estimated on the date of grant using the Black-Scholes model. The total cost is initially estimated based on the number of warrants that will become exercisable. At each reporting date, the Company revises its estimates of the number of warrants that will become exercisable. The impact of the revision is recognized in the income statement over the remaining vesting period with a corresponding adjustment to equity.

Earnings/(loss)per share

Earnings/(loss)per share

Basic earnings/(loss) per share is computed on the basis of the weighted average number of ordinary shares outstanding during the period, excluding treasury shares.

Diluted earnings/(loss) per share is computed based on the weighted-average number of ordinary shares outstanding including the dilutive effect of warrants and bonds. Warrants and bonds are treated as dilutive, when and only when their conversion to ordinary shares would decrease the net profit per share from continuing operations.

Operating segments

Operating segments

The chief operating decision-maker, who is responsible for allocating resources and assessing performance of the Company, has been identified as the Board of Directors that makes strategic decisions.

The Company operates in one operating segment. Management has determined that there is only one operating segment based on the information reviewed by the Board of Directors. The Board of Directors considers the business of the Company from a general company-wide perspective based on the close interrelation between the different projects. No geographical financial information is currently available given the fact that the core operations are currently still in a research and development phase.

No disaggregated information on product level or geographical level or any other level is currently existing and hence also not considered by the Board for assessing performance or allocating resources.

Share capital

Share capital

Financial instruments issued by the Group are classified as equity only to the extent that they do not meet the definition or a financial liability of financial asset. Ordinary shares are classified as equity.

Incremental costs directly attributable to the issue of new ordinary shares are presented in equity as a deduction, net of tax, from the proceeds.

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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)

12 Months Ended

Dec. 31, 2017

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Summary of Foreign Exchange Issuers

The following foreign exchange rates have been used for the preparation of the accounts:

	Closing rate						Average rate
€1 = x foreign currency	2017		2016		2015		2017		2016		2015
US Dollar		1.1999		1.0522		1.0866		1.1271		1.1059		1.1135
GB Pound		0.8886		0.8533		0.7360		0.8724		0.8131		0.7267

Summary of Useful Lives of PPE

Depreciation is charged to the income statement on the following basis:

•   Buildings	10 years
•   Equipment	3 years
•   Hardware	3 years
•   Furniture	5 years
•   Equipment under leasing	The shorter of the useful life or the minimum leasing term
•   Leasehold improvements	The shorter of the useful life or the minimum leasing term

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FINANCIAL INSTRUMENTS AND FINANCIAL RISK MANAGEMENT Overview of financial instruments (Tables)

12 Months Ended

Dec. 31, 2017

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Summary of Financial Instrument and Financial Risk Mangement

	As at December 31,
€ in thousands	2017		2016		2015
Financial assets		356,377		238,952		243,024
Restricted cash		1,601		1,600		1,648
Trade receivables		2,111		3,512		6,782
Current financial assets		337,714		180,484		230,992
Cash and cash equivalents		14,951		53,356		3,602
Total financial assets		356,377		238,952		243,024
At fair value through profit or loss		66,454		19,812		54,146
Convertible bond - Embedded derivative		66,454		19,812		54,146
At amortized cost		104,280		104,856		92,338
Convertible bond - Host debt		88,715		84,537		80,682
Total Trade payables		15,565		20,319		11,656
Total financial liabilities		170,734		124,668		146,484

Summary of Fair Value of Components Financial Instruments

The following table presents the fair values of the components of the convertible bond and the related fair value (FV) level:

€ in thousands	Carrying amount		Fair Value		Level of FV hierarchy IFRS 13
At 31 December 2017
Financial assets
Other financial assets		49,718		49,718		Level 3
As at December 31, 2017
Convertible bond
Host debt		88,715		97,296		Level 2
Embedded derivative		66,454		66,454		Level 3
As at December 31, 2016
Convertible bond
Host debt		84,537		88,708		Level 2
Embedded derivative		19,812		19,812		Level 3
As at December 31, 2015
Convertible bond
Host debt		80,682		84,798		Level 2
Embedded derivative		54,146		54,146		Level 3

Schedule of Reconciliation of Level 3

Reconciliation of the Level 3 instrument:

At issuance of other financial assets	50,000
Included in profit or loss	(278)
Closing Balance December 31, 2017	49,723
At issuance of the convertible bond	19,500
Included in profit or loss as a change in fair value	34,646
Closing Balance December 31, 2015	54,146
Included in profit or loss as a change in fair value	(34,334)
Closing Balance December 31, 2016	19,812
Included in profit or loss as a change in fair value	46,642
Closing Balance December 31, 2017	66,454

Schedule of Reconciliation of Level 3

Reconciliation of the Level 3 instrument:

At issuance of other financial assets	50,000
Included in profit or loss	(278)
Closing Balance December 31, 2017	49,723
At issuance of the convertible bond	19,500
Included in profit or loss as a change in fair value	34,646
Closing Balance December 31, 2015	54,146
Included in profit or loss as a change in fair value	(34,334)
Closing Balance December 31, 2016	19,812
Included in profit or loss as a change in fair value	46,642
Closing Balance December 31, 2017	66,454

Summary of Sensitivity of Fair Value of Significant Non-observable Inputs

The sensitivity of the fair value to significant non-observable inputs:

Assumptions as at December 31, 2017	Fair value other financial asset
Credit spread		31 bps	49,718
Sensitivity analysis
Credit spread
+1 bps		32 bps	49,704
- 1 bps		30 bps	49,729
Assumptions as at December 31, 2017	Fair value embedded derivative convertible bond
Credit spread		450 bps	66,454
Share price	€	20.72
Sensitivity analysis
Credit spread
-100 bps		350 bps	64,157
+100 bps		550 bps	68,671
Share price
+1%	€	20.93	68,077
-1%	€	20.51	64,803
Assumptions as at December 31, 2016	Fair value embedded derivative convertible bond
Credit spread		700 bps	19,812
Share price	€	10.82
Sensitivity analysis
Credit spread
-100 bps		600 bps	20,149
+100 bps		800 bps	19,497
Share price
+1%	€	10.92	19,900
-1%	€	10.71	19,726
Assumptions as at December 31, 2015	Fair value embedded derivative convertible bond
Credit spread		700 bps	51,405
Sensitivity analysis
Credit spread
-200 bps		500 bps	54,534
+200 bps		900 bps	48,802

Schedule of Credit Quality of Financial Assets

Credit quality of financial assets:

				As at December 31,
€ in thousands	Rating			2017		2016		2015
Cash and cash equivalents		A	+		9,465		35,131		3,522
		A			4,035				38
		A	-		1,451		18,225		42
					14,951		53,356		3,602
Current financial assets		A	+		99,996		100,003		56,026
		A			10,000		0		73,500
		A	-		227,718		80,481		101,466
					337,714		180,484		230,992
Total		A	+		109,461		135,134		59,548
		A			14,035		0		73,538
		A	-		229,169		98,706		101,508
					352,665		233,840		234,594

Summary of Net Foreign Currency Position

The table below provides an indication of the Company’s open net foreign currency position as per year end:

	As at December 31,
€ in thousands	2017		2016		2015
Liabilities denominated in USD		180		608		142
Liabilities denominated in GBP		182		167		76
Assets denominated in USD		105		65		2,680

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INTANGIBLE ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

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INTANGIBLE ASSETS

INTANGIBLE ASSETS

€ in thousands	Patents			Software			Total
Cost		2,174			2,473			4,647
Accumulated amortization and impairment		(2,080	)		(2,128	)		(4,208	)
Carrying amount at January 1, 2015		94			345			439
Additions		0			101			101
Amortization expense		(7	)		(194	)		(201	)
Carrying amount at December 31, 2015		87			252			339
Cost		2,174			2,574			4,748
Accumulated amortization and impairment		(2,087	)		(2,322	)		(4,409	)
Carrying amount at January 1, 2016		87			252			339
Additions		0			1,730			1,730
Amortization expense		(7	)		(477	)		(484	)
Carrying amount at December 31, 2016		80			1,505			1,585
Cost		2,174			4,304			6,478
Accumulated amortization and impairment		(2,094	)		(2,799	)		(4,893	)
Carrying amount at January 1, 2017		80			1,505			1,585
Additions					490			490
Amortization expense		(7	)		(833	)		(841	)
Carrying amount at December 31, 2017		72			1,162			1,234
Cost		2,174			4,794			6,968
Accumulated amortization and impairment		(2,102	)		(3,632	)		(5,734	)

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PROPERTY, PLANT & EQUIPMENT (Tables)

12 Months Ended

Dec. 31, 2017

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PROPERTY, PLANT & EQUIPMENT

PROPERTY, PLANT & EQUIPMENT

€ in thousands	Land and buildings			Equipment			Furniture			Equipment under leasing			Leasehold improve- ments			Total
Cost		0			11,418			2,049			2,181			847			16,495
Accumulated depreciation and impairment		0			(10,373	)		(1,678	)		(1,388	)		(755	)		(14,194	)
Carrying amount at January 1, 2015		0			1,045			371			793			92			2,301
Additions		413			960			50			0			36			1,459
Depreciation charge		(24	)		(642	)		(223	)		(230	)		(21	)		(1,140	)
Carrying amount at December 31, 2015		389			1,363			198			563			107			2,620
Cost		413			12,378			2,099			2,181			883			17,954
Accumulated depreciation and impairment		(24	)		(11,015	)		(1,901	)		(1,618	)		(776	)		(15,334	)
Carrying amount at January 1, 2016		389			1,363			198			563			107			2,620
Additions		0			2,421			346			0			120			2,887
Depreciation charge		(34	)		(1,267	)		(179	)		(230	)		(51	)		(1,761	)
Carrying amount at December 31, 2016		355			2,517			365			333			176			3,746
Cost		413			14,799			2,445			2,181			1,003			20,841
Accumulated depreciation and impairment		(58	)		(12,282	)		(2,080	)		(1,848	)		(827	)		(17,095	)
Carrying amount at January 1, 2017		355			2,517			365			333			176			3,746
Additions					2,022			183						118			2,323
Depreciation charge		(34	)		(1,664	)		(176	)		(229	)		(89	)		(2,193	)
Carrying amount at December 31, 2017		321			2,875			372			104			205			3,876
Cost		413			16,821			2,628			2,181			1,121			23,164
Accumulated depreciation and impairment		(92	)		(13,946	)		(2,256	)		(2,077	)		(916	)		(19,288	)

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RESTRICTED CASH (Tables)

12 Months Ended

Dec. 31, 2017

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Restricted Cash Related to Cash Pledge

Restricted cash is related to a cash pledge the Company has provided in respect of the service agreement with

Bio-Versneller NV (see note 30).

	As at December 31,
€ in thousands	2017		2016		2015
Restricted cash		1,601		1,600		1,648

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TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS

TRADE AND OTHER RECEIVABLES AND OTHER CURRENT ASSETS

	As at December 31,
€ in thousands	2017		2016		2015
Trade receivables		2,111		3,512		6,782
Total trade receivables		2,111		3,512		6,782
Value added tax receivables		1,162		887		626
Withholding taxes on interest income		289		420		528
Other receivables		94		12		1,350
Total other receivables		1,545		1,319		2,504
Total trade and other receivables		3,656		4,831		9,286

Trade and Other Receivables Related to Limited Number of Partners and Considered Fully Recoverable

The trade receivables relate to a limited number of partners and are considered fully recoverable. Currently, there are no past due trade receivables.

	As at December 31,
€ in thousands	2017		2016		2015
Accrued income		908		1,080		569
Deferred expenses		1,378		561		461
Total other current assets		2,286		1,641		1,030

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CASH AND CASH EQUIVALENTS (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

CASH AND CASH EQUIVALENTS

CASH AND CASH EQUIVALENTS

	As at December 31,
€ in thousands	2017		2016		2015
Cash at bank and on hand		14,951		53,356		3,602
Total cash and cash equivalents		14,951		53,356		3,602
of which : cash and cash equivalents in Euro		14,843		53,291		922
of which : cash and cash equivalents in foreign currency		108		65		2,680

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SHARE CAPITAL (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Capital

Overview of capital transactions

	Shares
Number of shares outstanding on January 1, 2015		54,014,159
Exercise of warrants - January 19, 2015		115,946
Exercise of warrants - March 16, 2015		174,302
Exercise of warrants - April 17, 2015		20,165
Exercise of warrants - June 3, 2015		83,000
Exercise of warrants - July 17, 2015		79,885
Exercise of warrants - July 29, 2015		24,967
Exercise of warrants - October 19, 2015		5,200
Exercise of warrants - December 7, 2015		7,250
Exercise of warrants - December 15, 2015		287,500
Number of shares outstanding on January 1, 2016		54,812,374
Exercise of warrants - January 18, 2016		288,170
Exercise of warrants - February 17, 2016		7,521
Exercise of warrants - March 17, 2016		210,741
Exercise of warrants - April 20, 2016		18,400
Private placement - June 1, 2016		5,533,720
Exercise of warrants - July 19, 2016		39,818
Exercise of warrants - October 18, 2016		10,050
Exercise of warrants - November 9, 2016		938
Number of shares outstanding on January 1, 2017		60,921,732
Exercise of warrants - January 17, 2017		154,342
Exercise of warrants - April 19, 2017		57,125
Exercise of warrants - July 18, 2017		19,833
Exercise of warrants - August 8, 2017		16,700
Exercise of warrants - September 13, 2017		249,563
Exercise of warrants - October 19, 2017		156,849
IPO Nasdaq - October 27, 2017		11,430,000
IPO Nasdaq - October 30, 2017		1,714,500
Number of shares outstanding on December 31, 2017		74,720,644

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SHARE-BASED COMPENSATIONS (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Overview of Share-Based Compensation Arrangements

Overview of share-based compensation arrangements

		Exercise price		Fair value		Number of warrants		Outstanding warrants at December 31
Warrant plan	Expiry date	(in €)		(in €)		granted		2017		2016
Plan - July 13, 2006	July 12, 2018		2.00		1.26		875,000		210,000		560,000
Plan - December 29, 2006	December 28, 2018		2.80		1.76		67,500		5,000		9,500
Plan - June 14, 2007	June 13, 2019		2.80		1.80		212,500		0		0
Plan - October 12, 2007	October 11, 2017		7.00		3.78		10,713		0		3,517
Plan - Augustus 22, 2008	August 21, 2015		4.88		3.11		75,000		0		0
Plan - Augustus 22, 2008	August 21, 2020		4.88		3.11		300,000		70,417		73,917
Plan - September 29, 2009	September 28, 2016		6.99		5.25		205,400		0		0
Plan - October 30, 2009	October 29, 2016		8.19		5.07		170,000		0		0
Plan - December 3, 2010	December 2, 2017		8.24		4.49		85,500		0		25,250
Plan - April 28, 2011	April 27, 2016/2018		8.68		3.78-4.48		387,050		22,500		72,892
Plan - February 1, 2012	January 31, 2017/2019		3.21		1.38-1.64		748,750		91,950		119,512
Plan - April 26, 2012	April 25, 2017/2019		3.23		1.47-1.74		162,500		0		46,875
Plan - November 6, 2012	November 5, 2017/2019		5.44		2.15-2.89		17,868		0		5,269
Plan - January 29, 2013	January 28, 2019		6.46		3.18-4.04		391,330		186,206		297,744
Plan - August 5, 2013	August 4, 2020		6.79		3.86-4.07		324,840		64,590		258,693
Plan - November 25, 2013	November 24, 2018		7.27		3.86-4.07		50,000		50,000		50,000
Plan - April 24, 2014	April 23, 2019/2021		8.81		3.06-3.80		327,224		287,732		295,469
Plan - March 16, 2015	March 15, 2022		9.98		3.71-3.92		442,801		425,019		439,936
Plan - September 14, 2015	September 13, 2022		12.10/12.29		5.20		233,000		215,500		218,300
Plan - February 24, 2016	February 23, 2023		12.02		4.92		429,479		377,899		416,952
Plan - February 22, 2017	February 21, 2024		12.33		5.11		527,061		499,745		0
Plan - September 20, 2017	September 19, 2024		12.26-14.53		4.77		291,500		291,500		0
Total							6,335,016		2,798,058		2,893,880

Reconciliation of share options outstanding

The following reconciles the share options outstanding at the beginning and end of the year:

	Number of warrants			Average exercise price (in €)
Outstanding warrants at January 1, 2015		3,015,978			5.71
Granted		525,801			10.34
Forfeited		(67,569	)		7.16
Exercised		(798,215	)		5.90
Expired		(964	)		8.59
Outstanding warrants at December 31, 2015		2,675,031			6.22
Granted		579,479			12.04
Forfeited		(69,742	)		9.45
Exercised		(575,638	)		3.91
Expired		0			0.00
Outstanding warrants at December 31, 2016		2,609,130			7.94
Granted		818,561			12.33
Forfeited		(68,227	)		11.27
Exercised		(654,412	)		0.24
Expired		(4,494	)		12.16
Outstanding warrants at December 31, 2017		2,700,558			11.30

Summary of Valuation of Fair Value of Warrants

The fair value of the warrants has been determined at grant date based on the Black-Scholes formula. The variables used in this model are:

Warrant plan	Expected dividend yield		Expected stock price volatility			Risk-free interest rate			Expected duration		Fair value (in €)
Plan - July 13,2006		0.00		60.0	%		3.95	%		7.00		0.63
Plan - December 29, 2006		0.00		60.0	%		3.95	%		7.00		0.88
Plan - June 14, 2007		0.00		60.0	%		4.63	%		7.00		0.90
Plan - October 12, 2007		0.00		60.0	%		4.22	%		4.78		3.78
Plan - Augustus 22, 2008		0.00		60.0	%		4.42	%		7.00		3.11
Plan - September 29, 2009		0.00		60.0	%		3.14	%		7.00		5.25
Plan - October 30, 2009		0.00		60.0	%		3.11	%		7.00		5.07
Plan - December 3, 2010		0.00		50.0	%		3.46	%		7.00		4.49
Plan - April 28, 2011		0.00		55.0	%		2.35%-2.84	%		5.00-7.00		1.38-1.64
Plan - February 1, 2012		0.00		55.0	%		2.83%-3.65	%		5.00-7.00		1.47-1.74
Plan - April 26, 2012		0.00		49.0%-56.0	%		1.09%-1.78	%		5.00-7.00		2.15-2.89
Plan - November 6, 2012		0.00		53.4%-54.0	%		1.54%-1.88	%		6.60-7.00		3.18-4.04
Plan - January 29, 2013		0.00		52.7%-53.8	%		1.56%-2.08	%		6.70-7.00		3.86-4.07
Plan - August 5, 2013		0.00		52.7%-53.8	%		1.56%-2.08	%		6.70-7.00		3.86-4.07
Plan - November 25, 2013		0.00		40.9	%		0.91%-1.50	%		5.00-7.00		3.06-3.80
Plan - April 24, 2014		0.00		40.6	%		0.2	%		7.00		3.71-3.92
Plan - March 16, 2015		0.00		40.9	%		0.6	%		7.00		5.20
Plan - September 14, 2015		0.00		40.9	%		0.6	%		7.00		5.20
Plan - February 24, 2016		0.00		42.6	%		0.2	%		7.00		4.92
Plan - February 22, 2017		0.00		39.1	%		0.21	%		7.00		5.11
Plan - September 20, 2017		0.00		37.7	%		0.08	%		7.00		4.77

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Financial Liabilities (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Components of Financial Liabilites

	As at December 31,
€ in thousands	2017		2016		2015
Convertible bond
Host debt		88,715		84,537		80,682
Embedded derivative		66,454		19,812		54,146
Financial liabilities		155,169		104,349		134,828
of which : non-current		155,169		104,349		134,828

Schedule of Company's Remaining Contractual Maturity of Finanacial Liabilities

	As at December 31,
€ in thousands	2017		2016		2015
Borrowings
Within one year		3,250		3,250		3,250
Between 2 and 5 years		104,875		108,125		111,375
Over 5 years				0		0
Total		108,125		111,375		114,625

Summary of Financial Liabilities at Fair Value

BORROWINGS AT FAIR VALUE
Closing Balance at December 31, 2016	104,349
Financing cash flows	(3,250	)
Payment of interests	(3,250	)
Non-cash changes	54.070
Effective Intrest Rate	7,427
Changes in fair value of derivative	46,642
Closing Balance year ended December 31, 2017	155,169

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TRADE AND OTHER PAYABLES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Trade and Other Payable

TRADE AND OTHER PAYABLES

	As at December 31,
€ in thousands	2017		2016		2015
Trade payables		4,761		5,519		4,263
Accruals for invoices to be received		10,804		14,800		7,393
Total trade payables		15,565		20,319		11,656
Social security		852		753		561
Payroll payables		5,705		4,654		4,194
Other liabilities		5		12		1
Total other payables		6,562		5,419		4,756
Total trade and other payables		22,127		25,738		16,412

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DEFERRED INCOME (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Deferred Income

Deferred income mainly relates to cash received from research collaboration agreements prior to completion of the earnings process.

	As at December 31,
€ in thousands	2017		2016		2015
Within 1 year		21,905		22,118		55,738
In the second to the fifth year		10,791		11,504		30,385
Total deferred income*		32,696		33,622		86,123

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Revenue (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summery of Components of Revenue

	Year ended December 31,
€ in thousands	2017		2016		2015
Upfront fees		24,752		52,311		58,559
Research and development service fees		13,255		13,875		14,403
Milestone payments		17,500		18,400		3,500
License fees & other revenue		55		187		299
Total		55,562		84,773		76,761

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Grant Income (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Detailed Information of Government Grants

€ in thousands	Amount granted		Received at December 31,						Still to receive at December 31,						Recognised as grant income for the years ended December 31,
			2017		2016		2015		2017		2016		2015		2017			2016		2015
IWT 18		886		886		886		708		0		0		178		0			178		0
IWT 19		1,113		1,113		1,674		1,116		0		420		978		(76	)		120		484
IWT 20		445		445		356		267		0		89		178		89			89		75
IWT 21		243		243		368		276		0		92		184		(44	)		27		220
Total		2,687		2,687		3,284		2,367		0		601		1,518		(31	)		414		779

The Company received several grants to support various research programs from an agency of the Flemish government to support technological innovation in Flanders (‘IWT’ – Agency for Innovation and Entrepreneurship). These grants carry clauses which require the Company to maintain a presence in the Flemish region for a number of years and invest according to pre-agreed budgets. The amounts still to receive mentioned in the table above are not recognized as receivables in the statement of financial position as there are conditions attached which are not yet met.

The Company received a fixed percentage of the expenses incurred in the following research and development projects:

IWT 18: T-cell recruiting Nanobodies for targeted delivery

Grantor:		IWT
Start date:		June 1, 2013
End date:		May 31, 2015
Amount granted:	€	885,597
Amount recognized:	€	885,597
Amount received:	€	885,597

IWT 19: Development of a novel Nanobody-based therapeutic platform for treatment of ocular diseases

Grantor:		IWT
Start date:		April 1, 2014
End date:		March 31, 2017
Amount granted:	€	1,112,926
Amount recognized:	€	1,112,926
Amount received:	€	1,112,926

IWT 20: Bispecific Nanobodies with enhanced specificity

Grantor:		IWT
Start date:		June 1, 2014
End date:		May 31, 2016
Amount granted:	€	445,027
Amount recognized:	€	445,027
Amount received:	€	445,027

IWT 21: Development of Nanobody-based immunotoxins

Grantor:		IWT
Start date:		June 1, 2014
End date:		May 31, 2016
Amount granted:	€	243,489
Amount recognized:	€	243,489
Amount received:	€	243,489

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RESEARCH AND DEVELOPMENT EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

RESEARCH AND DEVELOPMENT EXPENSES

RESEARCH AND DEVELOPMENT EXPENSES

	Year ended December 31,
€ in thousands	2017			2016			2015
Consumables		5,821			5,916			4,448
Outsourcing		52,655			65,925			53,897
Patent costs		2,868			2,134			2,177
Employee expenses		30,426			26,707			22,799
Share-based compensation expense		867			808			751
Other operating expenses		6,746			5,825			5,281
Reduction withholding tax for scientists		(4,119	)		(3,702	)		(3,381	)
Research and development incentives		(6,916	)		(5,078	)		(3,873	)
Subtotal		88,348			98,535			82,099
Depreciation and amortization expenses		2,573			1,780			985
Total research and development expenses		90,920			100,315			83,084

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GENERAL AND ADMINISTRATIVE EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

GENERAL AND ADMINISTRATIVE EXPENSES

	Year ended December 31,
€ in thousands	2017			2016			2015
Employee benefit expenses		4,217			3,588			3,092
Share-based compensation expense		1,739			1,764			1,069
Executive Committee compensation(1)		3,787			3,406			3,341
Consultancy		5,904			2,414			1,870
Other operating expenses		2,859			2,055			1,887
Reduction withholding tax for scientists		(162	)		(220	)		(204	)
Subtotal		18,344			13,007			11,055
Depreciation and amortization expenses		461			465			356
Total general and administrative expenses		18,805			13,472			11,411

1 The Executive Committee consists of key management members and entities controlled by them.

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EMPLOYEE BENEFITS EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

EMPLOYEE BENEFITS EXPENSES

	Years ended December 31,
€ in thousands	2017			2016			2015
Salaries, wages and bonuses		24,416			20,986			18,233
Social security		6,336			5,730			4,779
Post-employment benefits		1,839			1,026			881
Share-based compensation expense		2,606			2,572			1,820
Other employment costs		2,089			2,548			1,997
Executive Committee compensation1		3,750			3,406			3,341
Reduction withholding tax for scientists		(4,282	)		(3,922	)		(3,585	)
Total		36,755			32,346			27,466
Average full-time equivalents (FTE)
Executive committee(1)		7			7			8
R&D personnel		363			321			284
General and administrative staff		49			36			33
Average FTE		419			364			325

(1) The Executive Committee consists of key management members and the entities controlled by them.

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OPERATING LEASES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Summary of Non-cancellable Operating Lease Commitments

The following table presents the non-cancellable operating lease commitments:

	Years ended December 31,
€ in thousands	2017		2016		2015
Within 1 year		3,902		3,853		3,277
In the second to the fifth year		9,557		12,598		4,750
After five years		0		0		0

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FINANCIAL INCOME AND EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Financial Income and Expenses

	Years ended December 31,
€ in thousands	2017			2016			2015
Financial income
Interest income on financial assets		49			298			1,101
Financial income related to convertible bond
Changes in fair value of embedded derivative					34,334
Other financial income		400			129			667
Total		449			34,761			1,768
Financial expenses
Interest charges on financial liabilities
Financial expenses related to convertible bond
Changes in fair value of embedded derivative		(46,642	)					(34,646	)
Interest expenses on convertible bond		(7,427	)		(7,105	)		(4,074	)
Financing charges								(549	)
Other financial expenses		(717	)		(143	)		(91	)
Total		(54,786	)		(7,248	)		(39,360	)
Net financial result		(54,337	)		27,513			(37,592	)

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INCOME TAX EXPENSES (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

INCOME TAX EXPENSES

INCOME TAX EXPENSES

	Years ended December 31,
€ in thousands	2017			2016			2015
Loss of the year		(108,532	)		(1,087	)		(54,547	)
Income taxes calculated at 33.99%		36,890			369			18,541
Effect of income that is exempt from taxation		368			490			558
Effect of expenses that are not deductible in determining taxable profit		(248	)		(219	)		(199	)
Effect of unused tax losses and tax offsets not recognised as deferred tax assets		(37,010	)		(641	)		(18,899	)
Effective income taxes		(0	)		(0	)		0

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LOSS PER SHARE (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Disclosure of Computation of Basic and Diluted Earnings per Share

Earnings/losses per share are calculated by dividing the net result attributable to equity holders by the weighted average numbers of shares during the year.

	Years ended December 31,
	2017			2016*			2015
Basic gain/(loss) per share (in €)		(1.74	)		(0.02	)		(1.00	)
Diluted gain/(loss) per share (in €)		(1.74	)		(0.43	)		(1.00	)
	Years ended December 31,
Basic loss per share	2017			2016*			2015
Loss of the year (In thousands of €)		(108,532	)		(1,087	)		(54,547	)
Weighted average number of shares outstanding		62,322,875			58,499,545			54,382,147
Basic loss per share (in €)		(1.74	)		(0.02	)		(1.00	)
Diluted loss per share	2017			2016			2015
Loss of the year as used for basic loss per share (In thousands of €)		(108,532	)		(1,087	)		(54,547	)
Adjustments to earnings relating to convertible bond		0			(27,229	)		0
Loss of the year (In thousands of €) for diluted earnings per share		(108,532	)		(28,316	)		(54,547	)
Weighted average number of shares outstanding		62,322,875			58,499,545			54,382,147
Adjustments to number of shares relating to convertible bond		0			7,733,952			0
Weighted average number of shares outstanding after dilution effect		62,322,875			66,233,497			54,382,147
Diluted loss per share (in €)		(1.74	)		(0.43	)		(1.00	)

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Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2017

Text block1 [abstract]

Schedule of Key Management Personnel Compensation

Key management consists of the members of the Executive Committee and the non-executive Directors and the entities controlled by any of them.

	Years ended December 31,
€ in thousands, except for number of management members	2017			2016			2015
Number of management members		7			7			8
Short-term employee benefits (salaries, social security, bonuses, lunch vouchers)		2,580			2,394			2,295
Post-employment benefits (group insurance)		284			183			166
Share-based compensation expense		1,512			1,547			834
Other employee benefits		129			130			124
Management fees		398			338			451
Retribution		(27	)		(32	)		(31	)
Total		4,875			4,560			3,839
Number of warrants granted (in units)		433,440			365,844			293,311
Cumulative outstanding warrants (in units)		1,507,149			1,824,259			1,744,645
Shares owned (in units)		577,805			402,805			205,805

Transactions with non-executive Directors:

	Years ended December 31,
€ in thousands	2017		2016		2015
Share-based compensation expense		1		13		41
Management fees		360		363		305
Total		361		376		346
Number of warrants offered or granted (in units)
Cumulative outstanding warrants (in units)		64,590		68,430		74,595
Non-vested warrants				2,432		22,831
Shares owned (in units)		31,434		31,165		25,000

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Corporate Information- Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017 Subsidiary
Disclosure of corporate information [abstract]
Number of fully owned subsidiary	1

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Basis of Preparation - Additional Information (Detail) € in Millions	Dec. 31, 2017 EUR (€)
Basis Of Presentation [Abstract]
Non-Cancellable Operating lease commitments	€ 13.5

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Summary of Significant Accounting Policies - Foreign Exchange Rate (Detail) - Exchange_Rate	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
US Dollar [member]
Disclosure of foreign exchange rates [Line Items]
Closing foreign exchange rate	1.1999	1.0522	1.0866
Average foreign exchange rate	1.1271	1.1059	1.1135
GB Pound [member]
Disclosure of foreign exchange rates [Line Items]
Closing foreign exchange rate	0.8886	0.8533	0.7360
Average foreign exchange rate	0.8724	0.8131	0.7267

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Summary of Significant Accounting Policies - Additional Information (Detail) - Segment	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	Maximum three years
Employee benefits, minimum return guaranteed by employer		1.75%	3.25%
Percentage of contribution by employee			3.75%
Number of operating segment	1
Bottom of range [member]
Disclosure Of Summary Of Significant Accounting Policies [Line Items]
Employee benefits, minimum return guaranteed by employer	1.75%
Top of range [member]
Disclosure Of Summary Of Significant Accounting Policies [Line Items]
Employee benefits, minimum return guaranteed by employer	3.75%

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Summary of Significant Accounting Policies - Useful Life of Asset (Detail)	12 Months Ended
	Dec. 31, 2017
Buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated Useful Life Of Property Plant And Equipment	10 years
Equipment [Member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated Useful Life Of Property Plant And Equipment	3 years
Hardware [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated Useful Life Of Property Plant And Equipment	3 years
Furniture [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated Useful Life Of Property Plant And Equipment	5 years
Property, plant and equipment under operating leases [member]
Disclosure of detailed information about property, plant and equipment [line items]
Estimated Useful Life Of Property Plant And Equipment	The shorter of the useful life or the minimum leasing term

XML

Significant Account Judgments - Additional Information (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Derivative financial liabilities [Abstract]
Embedded derivative amounts	€ 66,454	€ 19,812	€ 54,146

XML

Financial Instruments and Financial Risk Management - Summary of Financial Instrument and Financial Risk Management (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of detailed information about financial instruments [abstract]
Financial assets	€ 356,377	€ 238,952	€ 243,024
Restricted cash	1,601	1,600	1,648
Trade receivables	2,111	3,512	6,782
Current financial assets	337,714	180,484	230,992
Cash and cash equivalents	14,951	53,356	3,602	€ 11,661
Total financial assets	356,377	238,952	243,024
At fair value through profit or loss	66,454	19,812	54,146
Convertible bond - Embedded derivative	66,454	19,812	54,146
At amortized cost	104,280	104,856	92,338
Convertible bond - Host debt	88,715	84,537	80,682
Total Trade payables	15,565	20,319	11,656
Total financial liabilities	€ 170,734	€ 124,668	€ 146,484

XML

Financial Instruments and Financial Risk Management - Components of Convertible Bond and Related Fair Value (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
Convertible bond Host debt	€ 88,715	€ 84,537	€ 80,682
Embedded derivative	66,454	19,812	54,146
At fair value [member]
Disclosure of detailed information about financial instruments [line items]
Other financial assets	49,718
Convertible bond Host debt	88,715	84,537	80,682
Embedded derivative	66,454	19,812	54,146
At fair value [member] | Level 3 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Other financial assets	49,718
Embedded derivative	66,454	19,812	54,146
At fair value [member] | Level 2 of fair value hierarchy [member]
Disclosure of detailed information about financial instruments [line items]
Convertible bond Host debt	€ 97,296	€ 88,708	€ 84,798

XML

Financial Instruments and Financial Risk Management - Summary of Reconciliation of Level 3 Instruments (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
At issuance of other financial assets	€ 266,764	€ 265,272
At Closing of other financial assets, Balance December 31, 2017	389,848	266,764	€ 265,272
Level 3 of fair value hierarchy [member] | Convertible bonds [member]
Disclosure of detailed information about financial instruments [line items]
At issuance of the convertible bond	19,812	54,146	19,500
Included in profit or loss as a change in fair value	46,642	(34,334)	34,646
Closing Balance	66,454	19,812	€ 54,146
Level 3 of fair value hierarchy [member] | Other financial assets [member]
Disclosure of detailed information about financial instruments [line items]
At issuance of other financial assets	50,000
Included in profit or loss	(278)
At Closing of other financial assets, Balance December 31, 2017	€ 49,723	€ 50,000

XML

Financial Instruments and Financial Risk Management - Summary of Sensitivity of Fair Value to Significant Non-Observable Inputs (Detail) - EUR (€) € / shares in Units, € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	€ 66,454	€ 19,812	€ 54,146
Share price volatility analysis [Member] | Weighted average [member]
Disclosure of detailed information about financial instruments [line items]
Share price	€ 20.72	€ 10.82
Share price volatility analysis [Member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Share price	20.93	10.92
Share price volatility analysis [Member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Share price	€ 20.51	€ 10.71
Share price volatility analysis [Member] | Embedded Derivatives Convertible Bond [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	€ 68,077	€ 19,900
Share price volatility analysis [Member] | Embedded Derivatives Convertible Bond [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	€ 64,803	€ 19,726
Credit spread analysis [Member] | Weighted average [member]
Disclosure of detailed information about financial instruments [line items]
Price estimation measurement	31 bps
Price estimation	450 bps	700 bps	700 bps
Credit spread analysis [Member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Price estimation measurement	32 bps
Price estimation	550 bps	800 bps	900 bps
Credit spread analysis [Member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Price estimation measurement	30 bps
Price estimation	350 bps	600 bps	500 bps
Credit spread analysis [Member] | Embedded Derivatives Convertible Bond [member] | Weighted average [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	€ 66,454	€ 19,812	€ 51,405
Credit spread analysis [Member] | Embedded Derivatives Convertible Bond [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	68,671	19,497	48,802
Credit spread analysis [Member] | Embedded Derivatives Convertible Bond [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of embedded derivative convertible bond	64,157	€ 20,149	€ 54,534
Credit spread analysis [Member] | Other Financial assets, [member] | Weighted average [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of other financial asset	49,718
Credit spread analysis [Member] | Other Financial assets, [member] | Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of other financial asset	49,704
Credit spread analysis [Member] | Other Financial assets, [member] | Bottom of range [member]
Disclosure of detailed information about financial instruments [line items]
Fair value of other financial asset	€ 49,729

XML

Financial Instruments and Financial Risk Management - Additional Information (Detail) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about financial instruments [line items]
Restricted cash	€ 1,601,000	€ 1,600,000	€ 1,648,000
Ten percentage Strengthening in foreign exchange rate [Member]
Disclosure of detailed information about financial instruments [line items]
If the EUR had strengthened 10% against the GBP and against the USD with all other variables held constant	2,437.311	675.710
Ten percentage weakening in foreign exchange rate [Member]
Disclosure of detailed information about financial instruments [line items]
If the EUR had strengthened 10% against the GBP and against the USD with all other variables held constant	(1,994.163)	€ (552.854)
Privately Placed Bonds [Member]
Disclosure of detailed information about financial instruments [line items]
Unsecured bonds	€ 100,000,000
Coupon rate	3.25%
Conversion price	€ 12.66
Privately Placed Bonds [Member] | Original Conversion Price [Member]
Disclosure of detailed information about financial instruments [line items]
Conversion price	€ 12.93
Top of range [member]
Disclosure of detailed information about financial instruments [line items]
Deposits Maturity	1 year
Credit Linked Maturity	2 years

XML

Financial Instruments and Financial Risk Management - Credit Quality of Financial Assets (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	€ 14,951	€ 53,356	€ 3,602	€ 11,661
Current financial assets	337,714	180,484	230,992
Total financial assets	356,377	238,952	243,024
Other Financial assets, [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	14,951	53,356	3,602
Current financial assets	337,714	180,484	230,992
Total financial assets	352,665	233,840	234,594
A + [member] | Other Financial assets, [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	9,465	35,131	3,522
Current financial assets	99,996	100,003	56,026
Total financial assets	109,461	135,134	59,548
A credit rating [member] | Other Financial assets, [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	4,035		38
Current financial assets	10,000	0	73,500
Total financial assets	14,035	0	73,538
A - [Member] | Other Financial assets, [member]
Disclosure of detailed information about financial instruments [line items]
Cash and cash equivalents	1,451	18,225	42
Current financial assets	227,718	80,481	101,466
Total financial assets	€ 229,169	€ 98,706	€ 101,508

XML

Financial Instruments and Financial Risk Management - Summary of Net Foreign Currency Position (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Other Financial assets, [member] | US Dollar [member]
Disclosure of detailed information about financial instruments [line items]
Net foreign currency position	€ 105	€ 65	€ 2,680
Financial liabilities, class [member] | US Dollar [member]
Disclosure of detailed information about financial instruments [line items]
Net foreign currency position	180	608	142
Financial liabilities, class [member] | GB Pound [member]
Disclosure of detailed information about financial instruments [line items]
Net foreign currency position	€ 182	€ 167	€ 76

XML

Segment Information - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Three Parties [Member]
Disclosure of major customers [line items]
Income originated from parties, percentage	80.00%	85.00%
One Party [Member]
Disclosure of major customers [line items]
Income originated from parties, percentage	29.00%	40.00%	50.00%
Two Parties [Member]
Disclosure of major customers [line items]
Income originated from parties, percentage	27.00%
Two Parties [Member] | Bottom of range [member]
Disclosure of major customers [line items]
Income originated from parties, percentage		19.00%	15.00%
Two Parties [Member] | Top of range [member]
Disclosure of major customers [line items]
Income originated from parties, percentage		25.00%	23.00%

XML

Intangible Asset (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	€ 1,585	€ 339	€ 439
Additions	490	1,730	101
Amortization	(841)	(484)	(201)
Intangible assets, Ending balance	1,234	1,585	339
Gross carrying amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	6,478	4,748	4,647
Intangible assets, Ending balance	6,968	6,478	4,748
Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	(4,893)	(4,409)	(4,208)
Intangible assets, Ending balance	(5,734)	(4,893)	(4,409)
Patent [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	80	87	94
Additions		0	0
Amortization	(7)	(7)	(7)
Intangible assets, Ending balance	72	80	87
Patent [member] | Gross carrying amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	2,174	2,174	2,174
Intangible assets, Ending balance	2,174	2,174	2,174
Patent [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	(2,094)	(2,087)	(2,080)
Intangible assets, Ending balance	(2,102)	(2,094)	(2,087)
Computer software [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	1,505	252	345
Additions	490	1,730	101
Amortization	(833)	(477)	(194)
Intangible assets, Ending balance	1,162	1,505	252
Computer software [member] | Gross carrying amount [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	4,304	2,574	2,473
Intangible assets, Ending balance	4,794	4,304	2,574
Computer software [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about intangible assets [line items]
Intangible assets, Beginning balance	(2,799)	(2,322)	(2,128)
Intangible assets, Ending balance	€ (3,632)	€ (2,799)	€ (2,322)

XML

Property Plant Equipment (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	€ 3,746	€ 2,620	€ 2,301
Additions	2,323	2,887	1,459
Depreciation charge	(2,193)	(1,761)	(1,140)
Property, plant and equipment, Ending Balance	3,876	3,746	2,620
Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	20,841	17,954	16,495
Property, plant and equipment, Ending Balance	23,164	20,841	17,954
Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(17,095)	(15,334)	(14,194)
Property, plant and equipment, Ending Balance	(19,288)	(17,095)	(15,334)
Land and buildings [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	355	389	0
Additions		0	413
Depreciation charge	(34)	(34)	(24)
Property, plant and equipment, Ending Balance	321	355	389
Land and buildings [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	413	413	0
Property, plant and equipment, Ending Balance	413	413	413
Land and buildings [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(58)	(24)	0
Property, plant and equipment, Ending Balance	(92)	(58)	(24)
Office equipment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	2,517	1,363	1,045
Additions	2,022	2,421	960
Depreciation charge	(1,664)	(1,267)	(642)
Property, plant and equipment, Ending Balance	2,875	2,517	1,363
Office equipment [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	14,799	12,378	11,418
Property, plant and equipment, Ending Balance	16,821	14,799	12,378
Office equipment [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(12,282)	(11,015)	(10,373)
Property, plant and equipment, Ending Balance	(13,946)	(12,282)	(11,015)
Furniture [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	365	198	371
Additions	183	346	50
Depreciation charge	(176)	(179)	(223)
Property, plant and equipment, Ending Balance	372	365	198
Furniture [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	2,445	2,099	2,049
Property, plant and equipment, Ending Balance	2,628	2,445	2,099
Furniture [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(2,080)	(1,901)	(1,678)
Property, plant and equipment, Ending Balance	(2,256)	(2,080)	(1,901)
Property, plant and equipment under operating leases [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	333	563	793
Additions		0	0
Depreciation charge	(229)	(230)	(230)
Property, plant and equipment, Ending Balance	104	333	563
Property, plant and equipment under operating leases [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	2,181	2,181	2,181
Property, plant and equipment, Ending Balance	2,181	2,181	2,181
Property, plant and equipment under operating leases [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(1,848)	(1,618)	(1,388)
Property, plant and equipment, Ending Balance	(2,077)	(1,848)	(1,618)
Leasehold improvements [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	176	107	92
Additions	118	120	36
Depreciation charge	(89)	(51)	(21)
Property, plant and equipment, Ending Balance	205	176	107
Leasehold improvements [member] | Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	1,003	883	847
Property, plant and equipment, Ending Balance	1,121	1,003	883
Leasehold improvements [member] | Accumulated depreciation, amortisation and impairment [member]
Disclosure of detailed information about property, plant and equipment [line items]
Property, plant and equipment, Beginning Balance	(827)	(776)	(755)
Property, plant and equipment, Ending Balance	€ (916)	€ (827)	€ (776)

XML

Restricted Cash (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash and cash equivalents [abstract]
Restricted cash	€ 1,601	€ 1,600	€ 1,648

XML

Research and Development Incentive Receivables (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables from contracts with customers [abstract]
Non-current research and development incentives receivable	€ 22,081	€ 17,642	€ 14,517
Current research and development incentives receivable	2,449	1,879	1,238
Total	€ 24,530	€ 19,521	€ 15,755

XML

Research And Development Incentive Receivables - Additional Information (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Receivables from contracts with customers [abstract]
Research and development incentives receivable	€ 24,530	€ 19,521	€ 15,755

XML

Trade and Other receivables and Other Current Assets (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Trade and other current receivables [abstract]
Trade receivables	€ 2,111	€ 3,512	€ 6,782
Total Trade receivables	2,111	3,512	6,782
Value added tax receivables	1,162	887	626
Withholding taxes on interest income	289	420	528
Other receivables	94	12	1,350
Total other receivables	1,545	1,319	2,504
Total trade and other receivables	€ 3,656	€ 4,831	€ 9,286

XML

Trade Receivable related to Partner (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Trade and other current receivables [abstract]
Accrued income	€ 908	€ 1,080	€ 569
Deferred expenses	1,378	561	461
Total other current assets	€ 2,286	€ 1,641	€ 1,030

XML

Cash and Cash Equivalent (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of cash and cash equivalents [line items]
Cash at bank and on hand	€ 14,951	€ 53,356	€ 3,602
Total cash and cash equivalents	14,951	53,356	3,602	€ 11,661
Euro [member]
Disclosure of cash and cash equivalents [line items]
Total cash and cash equivalents	14,843	53,291	922
Foreign Currency [member]
Disclosure of cash and cash equivalents [line items]
Total cash and cash equivalents	€ 108	€ 65	€ 2,680

XML

Share Capital - Schedule of Overview of Capital Transactions (Detail) - shares																										12 Months Ended
	Oct. 30, 2017	Oct. 27, 2017	Oct. 19, 2017	Sep. 13, 2017	Aug. 08, 2017	Jul. 18, 2017	Apr. 19, 2017	Jan. 17, 2017	Nov. 09, 2016	Oct. 18, 2016	Jul. 19, 2016	Jun. 01, 2016	Apr. 20, 2016	Mar. 17, 2016	Feb. 17, 2016	Jan. 18, 2016	Dec. 15, 2015	Dec. 07, 2015	Oct. 19, 2015	Jul. 29, 2015	Jul. 17, 2015	Jun. 03, 2015	Apr. 17, 2015	Mar. 16, 2015	Jan. 19, 2015	Jul. 18, 2017	Dec. 15, 2015	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure of classes of share capital [line items]
Number of shares outstanding																												74,720,644	60,921,732	54,812,374	54,014,159
Warrants [member]
Disclosure of classes of share capital [line items]
Issuance of shares			156,849	249,563	16,700	19,833	57,125	154,342	938	10,050	39,818		18,400	210,741	7,521	288,170	287,500	7,250	5,200	24,967	79,885	83,000	20,165	174,302	115,946	19,833	287,500
Private placements [member]
Disclosure of classes of share capital [line items]
Issuance of shares												5,533,720
IPO Nasdaq [Member]
Disclosure of classes of share capital [line items]
Issuance of shares	1,714,500	11,430,000

XML

Share Capital - Additional Information (Detail) - EUR (€)																											12 Months Ended
		Oct. 30, 2017	Oct. 27, 2017	Oct. 19, 2017	Sep. 13, 2017	Aug. 08, 2017	Jul. 18, 2017	Apr. 19, 2017	Jan. 17, 2017	Nov. 09, 2016	Oct. 18, 2016	Jul. 19, 2016	Jun. 01, 2016	Apr. 20, 2016	Mar. 17, 2016	Feb. 17, 2016	Jan. 18, 2016	Dec. 15, 2015	Dec. 07, 2015	Oct. 19, 2015	Jul. 29, 2015	Jul. 17, 2015	Jun. 03, 2015	Apr. 17, 2015	Mar. 16, 2015	Jan. 19, 2015	Dec. 31, 2017	Jul. 18, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 15, 2015
Disclosure of classes of share capital [line items]
Exercise of warrant																											€ 3,471,000		€ 2,221,000	€ 5,161,000
Issuance of share capital																											195,327,000		74,152,000
Proceeds from issuance of shares	[1]																										179,256,000		71,442,000
Share capital [member]
Disclosure of classes of share capital [line items]
Exercise of warrant																											3,254,000		2,132,000	4,312,000
Issuance of share capital																											24,580,000		10,348,000
Share Premium Account [member]
Disclosure of classes of share capital [line items]
Exercise of warrant																											2,247,000		1,177,000	€ 3,671,000
Issuance of share capital																											€ 170,747,000		€ 63,804,000
Warrants [member]
Disclosure of classes of share capital [line items]
Issuance of shares				156,849	249,563	16,700	19,833	57,125	154,342	938	10,050	39,818		18,400	210,741	7,521	288,170	287,500	7,250	5,200	24,967	79,885	83,000	20,165	174,302	115,946		19,833			287,500
Exercise of warrant				€ 978,878.73	€ 878,950.09	€ 80,683.50	€ 121,444.25	€ 398,801.77	€ 1,011,939.05	€ 5,102.72	€ 47,303	€ 160,489.39		€ 76,630	€ 740,375.82	€ 34,726.41	€ 1,192,292.70	€ 1,532,750	€ 61,390	€ 41,249	€ 199,086.96	€ 600,491.30	€ 410,955	€ 112,425.70	€ 1,292,682.18	€ 909,426.07
Warrants [member] | Share capital [member]
Disclosure of classes of share capital [line items]
Exercise of warrant				293,307.63	466,682.81	31,229.00	37,087.71	106,823.75	288,619.54	1,754.06	18,793.50	77,947.16		34,408	394,085.67	14,064.27	538,877.90	535,000	13,557.50	9,724	46,688.29	149,384.95	155,210	37,603.55	325,944.74	216,819.02
Warrants [member] | Share Premium Account [member]
Disclosure of classes of share capital [line items]
Exercise of warrant				€ 685,571.1	€ 412,267.28	€ 49,454.50	€ 84,356.54	€ 291,978.02	€ 723,319.51	€ 3,348.66	€ 28,509.50	€ 82,542.23		€ 42,222	€ 346,290.15	€ 20,662.14	€ 653,414.80	€ 997,750	€ 47,832.50	€ 31,525	€ 152,398.67	€ 451,106.35	€ 255,745	€ 74,822.15	€ 966,737.44	€ 692,607.05
IPO Nasdaq [Member]
Disclosure of classes of share capital [line items]
Issuance of shares		1,714,500	11,430,000
Issuance of share capital		€ 25,477,470	€ 169,849,800
Proceeds from issuance of shares		25,500,000	169,800,000
IPO Nasdaq [Member] | Share capital [member]
Disclosure of classes of share capital [line items]
Issuance of share capital		3,206,115	21,374,100
IPO Nasdaq [Member] | Share Premium Account [member]
Disclosure of classes of share capital [line items]
Issuance of share capital		€ 22,271,355	€ 148,475,700
Private placements [member]
Disclosure of classes of share capital [line items]
Issuance of shares													5,533,720
Issuance of share capital													€ 74,151,848
Proceeds from issuance of shares													74,200,000
Private placements [member] | Share capital [member]
Disclosure of classes of share capital [line items]
Issuance of share capital													10,348,056.40
Private placements [member] | Share Premium Account [member]
Disclosure of classes of share capital [line items]
Issuance of share capital													€ 63,803,791.60

[1] The gross cash flow from the issue of shares amount to €195.3 million. The Company paid €16.1 million with respect to issuance costs

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Authorized Capital Voting Rights Dividends and Profit Appropriation - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of classes of share capital [line items]
Authorized Capital	€ 27,253	€ 54,470	€ 66,520
Voting right	Each share gives right to one vote
Dividend distribution	The Company has never distributed any dividends to its shareholders. According to Belgian company law, the Company is required to deduct at least 5% from its profit to constitute the legal reserve until it reaches one-tenth of the Company's statutory share capital. At December 31, 2017, no profits were available for distribution.
Bottom of range [member]
Disclosure of classes of share capital [line items]
Legal Reserve	5.00%

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Share based Compensation - 2015 Issuance - Additional Information (Detail)										12 Months Ended
	Sep. 20, 2017 shares	Sep. 14, 2017 shares € / shares	Feb. 27, 2017	Feb. 22, 2017 € / shares shares	Sep. 09, 2016 shares	Feb. 24, 2016 € / shares shares	Feb. 14, 2016	Sep. 14, 2015 shares € / shares	Mar. 16, 2015 shares € / shares	Dec. 31, 2017 shares
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrant vesting period	3 years			3 years			3 years
Warrants Term	7 years			7 years		7 years		7 years	7 years
Warrants Granted	629,000			527,061	0	429,479		233,000
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Expiration Date	Sep. 19, 2022		Mar. 21, 2022			Feb. 23, 2023		Sep. 13, 2022	Mar. 15, 2022
Maximum warrant Issuance	670,000			740,000	320,000	590,000		290,000
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Expiration Date	Jan. 01, 2021		Jan. 01, 2021			Jan. 01, 2020		Jan. 01, 2019	Jan. 01, 2019
After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting percentage	28.00%			28.00%			28.00%
After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Monthly vesting basis	900.00%
Warrants [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Granted									442,801	6,335,016
Warrants exercise price | € / shares				€ 12.33		€ 12.02			€ 0.0998
Warrant vesting period									4 years
Warrants [member] | Exercise price 12.10 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Granted		150,000
Warrants exercise price | € / shares		€ 12.10
Warrants [member] | Exercise price 12.29 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Granted								83,000
Warrants exercise price | € / shares								€ 12.29
Warrants [member] | Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Maximum number of shares approved for issuance									850,000
Warrants [member] | After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting percentage									25.00%
Warrants [member] | After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting percentage									75.00%
Monthly vesting basis									2.083%

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Share based Compensation - 2016 Issuance - Additional Information (Detail) - € / shares	Sep. 20, 2017	Feb. 27, 2017	Feb. 22, 2017	Sep. 09, 2016	Feb. 24, 2016	Feb. 14, 2016	Sep. 14, 2015	Mar. 16, 2015
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Granted	629,000		527,061	0	429,479		233,000
Warrant vesting period	3 years		3 years			3 years
Warrants Term	7 years		7 years		7 years		7 years	7 years
After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	28.00%		28.00%			28.00%
After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Quarterly vesting basis			9.00%			9.00%
Warrants [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price			€ 12.33		€ 12.02			€ 0.0998
Warrant vesting period								4 years
Warrants [member] | After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period								25.00%
Warrants [member] | After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period								75.00%
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Maximum warrant Issuance	670,000		740,000	320,000	590,000		290,000
Warrants Expiration Date	Sep. 19, 2022	Mar. 21, 2022			Feb. 23, 2023		Sep. 13, 2022	Mar. 15, 2022
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Expiration Date	Jan. 01, 2021	Jan. 01, 2021			Jan. 01, 2020		Jan. 01, 2019	Jan. 01, 2019

XML

Share based Compensation - 2017 Issuance - Additional Information (Detail) - € / shares	Sep. 20, 2017	Feb. 27, 2017	Feb. 22, 2017	Sep. 09, 2016	Feb. 24, 2016	Feb. 14, 2016	Sep. 14, 2015	Mar. 16, 2015
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Granted	629,000		527,061	0	429,479		233,000
Warrant vesting period	3 years		3 years			3 years
Warrants Term	7 years		7 years		7 years		7 years	7 years
After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period	28.00%		28.00%			28.00%
After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Quarterly vesting basis			9.00%			9.00%
Monthly vesting basis	900.00%
Warrants [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price			€ 12.33		€ 12.02			€ 0.0998
Warrant vesting period								4 years
Warrants [member] | Exercise Price 12.26 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	€ 12.26
Warrants [member] | Exercise Price 12.96 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	12.96
Warrants [member] | Exercise Price 13.32 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	13.32
Warrants [member] | Exercise Price 14.53 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	14.53
Warrants [member] | Exercise Price 17.84 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	17.84
Warrants [member] | Exercise Price 19.78 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	19.78
Warrants [member] | Exercise price 23.36 [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants exercise price	€ 23.36
Warrants [member] | After One Year [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period								25.00%
Warrants [member] | After One Year The Remaining [Member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Vesting period								75.00%
Monthly vesting basis								2.083%
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Maximum warrant Issuance	670,000		740,000	320,000	590,000		290,000
Warrants Expiration Date	Sep. 19, 2022	Mar. 21, 2022			Feb. 23, 2023		Sep. 13, 2022	Mar. 15, 2022
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Warrants Expiration Date	Jan. 01, 2021	Jan. 01, 2021			Jan. 01, 2020		Jan. 01, 2019	Jan. 01, 2019

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Share based Compensation - Fair Value Model - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2017
Disclosure of terms and conditions of share-based payment arrangement [abstract]
Warrants extension period	5 years
Fair value of warrant determination	Black-Scholes

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Share-based Compensation - Overview of Share-based Compensation Arrangements (Detail)							12 Months Ended
	Sep. 20, 2017	Feb. 27, 2017	Feb. 22, 2017 € / shares	Feb. 24, 2016 € / shares	Sep. 14, 2015	Mar. 16, 2015 shares € / shares	Dec. 31, 2017 EUR (€) shares € / shares	Dec. 31, 2016 shares
Warrants [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price | € / shares			€ 12.33	€ 12.02		€ 0.0998
Number of warrants granted						442,801	6,335,016
Outstanding warrants							2,798,058	2,893,880
Warrants [member] | Plan - July 13, 2006 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Jul. 12, 2018
Exercise price | € / shares							€ 2.00
Fair value | €							€ 1.26
Number of warrants granted							875,000
Outstanding warrants							210,000	560,000
Warrants [member] | Plan - December 29, 2006 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Dec. 28, 2018
Exercise price | € / shares							€ 2.80
Fair value | €							€ 1.76
Number of warrants granted							67,500
Outstanding warrants							5,000	9,500
Warrants [member] | Plan - June 14, 2007 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Jun. 13, 2019
Exercise price | € / shares							€ 2.80
Fair value | €							€ 1.80
Number of warrants granted							212,500
Outstanding warrants							0	0
Warrants [member] | Plan - October 12, 2007 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Oct. 11, 2017
Exercise price | € / shares							€ 7.00
Fair value | €							€ 3.78
Number of warrants granted							10,713
Outstanding warrants							0	3,517
Warrants [member] | Plan - Augustus 22, 2008 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Aug. 21, 2015
Exercise price | € / shares							€ 4.88
Fair value | €							€ 3.11
Number of warrants granted							75,000
Outstanding warrants							0	0
Warrants [member] | Plan - August 22, 2008 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Aug. 21, 2020
Exercise price | € / shares							€ 4.88
Fair value | €							€ 3.11
Number of warrants granted							300,000
Outstanding warrants							70,417	73,917
Warrants [member] | Plan - September 29, 2009 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Sep. 28, 2016
Exercise price | € / shares							€ 6.99
Fair value | €							€ 5.25
Number of warrants granted							205,400
Outstanding warrants							0	0
Warrants [member] | Plan - October 30, 2009 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Oct. 29, 2016
Exercise price | € / shares							€ 8.19
Fair value | €							€ 5.07
Number of warrants granted							170,000
Outstanding warrants							0	0
Warrants [member] | Plan - December 3, 2010 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Dec. 02, 2017
Exercise price | € / shares							€ 8.24
Fair value | €							€ 4.49
Number of warrants granted							85,500
Outstanding warrants							0	25,250
Warrants [member] | Plan - April 28, 2011 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Apr. 27, 2018
Exercise price | € / shares							€ 8.68
Number of warrants granted							387,050
Outstanding warrants							22,500	72,892
Warrants [member] | Plan - February 1, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Jan. 31, 2019
Exercise price | € / shares							€ 3.21
Number of warrants granted							748,750
Outstanding warrants							91,950	119,512
Warrants [member] | Plan - April 26, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Apr. 25, 2019
Exercise price | € / shares							€ 3.23
Number of warrants granted							162,500
Outstanding warrants							0	46,875
Warrants [member] | Plan - November 6, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Nov. 05, 2019
Exercise price | € / shares							€ 5.44
Number of warrants granted							17,868
Outstanding warrants							0	5,269
Warrants [member] | Plan - January 29, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Jan. 28, 2019
Exercise price | € / shares							€ 6.46
Number of warrants granted							391,330
Outstanding warrants							186,206	297,744
Warrants [member] | Plan - August 5, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Aug. 04, 2020
Exercise price | € / shares							€ 6.79
Number of warrants granted							324,840
Outstanding warrants							64,590	258,693
Warrants [member] | Plan - November 25, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Nov. 24, 2018
Exercise price | € / shares							€ 7.27
Number of warrants granted							50,000
Outstanding warrants							50,000	50,000
Warrants [member] | Plan - April 24, 2014 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Apr. 23, 2021
Exercise price | € / shares							€ 8.81
Number of warrants granted							327,224
Outstanding warrants							287,732	295,469
Warrants [member] | Plan - March 16, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Mar. 15, 2022
Exercise price | € / shares							€ 9.98
Number of warrants granted							442,801
Outstanding warrants							425,019	439,936
Warrants [member] | Plan - September 14, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Sep. 23, 2022
Fair value | €							€ 5.20
Number of warrants granted							233,000
Outstanding warrants							215,500	218,300
Warrants [member] | Plan - February 24, 2016 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Feb. 23, 2023
Exercise price | € / shares							€ 12.02
Fair value | €							€ 4.92
Number of warrants granted							429,479
Outstanding warrants							377,899	416,952
Warrants [member] | Plan - February 22, 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Feb. 21, 2024
Exercise price | € / shares							€ 12.33
Fair value | €							€ 5.11
Number of warrants granted							527,061
Outstanding warrants							499,745	0
Warrants [member] | Plan - September 20, 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date							Sep. 19, 2024
Fair value | €							€ 4.77
Number of warrants granted							291,500
Outstanding warrants							291,500	0
Bottom of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date	Jan. 01, 2021	Jan. 01, 2021		Jan. 01, 2020	Jan. 01, 2019	Jan. 01, 2019
Bottom of range [member] | Warrants [member] | Plan - April 28, 2011 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							€ 3.78
Bottom of range [member] | Warrants [member] | Plan - February 1, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							1.38
Bottom of range [member] | Warrants [member] | Plan - April 26, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							1.47
Bottom of range [member] | Warrants [member] | Plan - November 6, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							2.15
Bottom of range [member] | Warrants [member] | Plan - January 29, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							3.18
Bottom of range [member] | Warrants [member] | Plan - August 5, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							3.86
Bottom of range [member] | Warrants [member] | Plan - November 25, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							3.86
Bottom of range [member] | Warrants [member] | Plan - April 24, 2014 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							3.06
Bottom of range [member] | Warrants [member] | Plan - March 16, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							€ 3.71
Bottom of range [member] | Warrants [member] | Plan - September 14, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price | € / shares							€ 12.10
Bottom of range [member] | Warrants [member] | Plan - September 20, 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price | € / shares							€ 12.26
Top of range [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Expiry date	Sep. 19, 2022	Mar. 21, 2022		Feb. 23, 2023	Sep. 13, 2022	Mar. 15, 2022
Top of range [member] | Warrants [member] | Plan - April 28, 2011 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							€ 4.48
Top of range [member] | Warrants [member] | Plan - February 1, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							1.64
Top of range [member] | Warrants [member] | Plan - April 26, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							1.74
Top of range [member] | Warrants [member] | Plan - November 6, 2012 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							2.89
Top of range [member] | Warrants [member] | Plan - January 29, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							4.04
Top of range [member] | Warrants [member] | Plan - August 5, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							4.07
Top of range [member] | Warrants [member] | Plan - November 25, 2013 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							4.07
Top of range [member] | Warrants [member] | Plan - April 24, 2014 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							3.80
Top of range [member] | Warrants [member] | Plan - March 16, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Fair value | €							€ 3.92
Top of range [member] | Warrants [member] | Plan - September 14, 2015 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price | € / shares							€ 12.29
Top of range [member] | Warrants [member] | Plan - September 20, 2017 [member]
Disclosure of terms and conditions of share-based payment arrangement [line items]
Exercise price | € / shares							€ 14.53

XML

Share-based Payment - Reconciliation of Share Options Outstanding (Detail)	12 Months Ended
	Dec. 31, 2017 EUR (€) shares	Dec. 31, 2016 EUR (€) shares	Dec. 31, 2015 EUR (€) shares
Disclosure - Share-based Payment - Reconciliation of Share Options Outstanding [Abstract]
Outstanding warrants at beginning of year | shares	2,609,130	2,675,031	3,015,978
Number of warrants granted | shares	818,561	579,479	525,801
Number of warrants forfeited | shares	(68,227)	(69,742)	(67,569)
Number of warrants exercised | shares	(654,412)	(575,638)	(798,215)
Number of warrants expired | shares	(4,494)	0	(964)
Outstanding warrants at end of year | shares	2,700,558	2,609,130	2,675,031
Warrants average exercise price beginning or year | €	€ 7.94	€ 6.22	€ 5.71
Warrants average exercise price granted | €	12.33	12.04	10.34
Warrants average exercise price forfeited | €	11.27	9.45	7.16
Warrants average exercise price exercised | €	0.24	3.91	5.90
Warrants average exercise price expired | €	12.16	0.00	8.59
Warrants average exercise price end or year | €	€ 11.30	€ 7.94	€ 6.22

XML

Share-based Payment - Fair value of Warrants At Grant Date Based on Black-Scholes (Detail)	12 Months Ended
	Dec. 31, 2017 EUR (€) yr
Plan - July 13, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	3.95%
Expected duration	0
Fair value | €	€ 0.63
Plan - December 29, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	3.95%
Expected duration	0
Fair value | €	€ 0.88
Plan - June 14, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	4.63%
Expected duration	0
Fair value | €	€ 0.90
Plan - October 12, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	4.22%
Expected duration	0
Fair value | €	€ 3.78
Plan - Augustus 22, 2008 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	4.42%
Expected duration	0
Fair value | €	€ 3.11
Plan - September 29, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	3.14%
Expected duration	0
Fair value | €	€ 5.25
Plan - October 30, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	60.00%
Risk-free interest rate	3.11%
Expected duration	0
Fair value | €	€ 5.07
Plan - December 3, 2010 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	50.00%
Risk-free interest rate	3.46%
Expected duration	0
Fair value | €	€ 4.49
Plan - April 28, 2011 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	55.00%
Expected duration	0
Plan - February 1, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	55.00%
Expected duration	0
Plan - April 26, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected duration	0
Plan - November 6, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected duration	0
Plan - January 29, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected duration	0
Plan - August 5, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected duration	0
Plan - November 25, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	40.90%
Expected duration	0
Plan - April 24, 2014 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	40.60%
Risk-free interest rate	0.20%
Expected duration	0
Plan - March 16, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	40.90%
Risk-free interest rate	0.60%
Expected duration	0
Fair value | €	€ 5.20
Plan - September 14, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	40.90%
Risk-free interest rate	0.60%
Expected duration	0
Fair value | €	€ 5.20
Plan - February 24, 2016 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	42.60%
Risk-free interest rate	0.20%
Expected duration	0
Fair value | €	€ 4.92
Plan - February 22, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	39.10%
Risk-free interest rate	0.21%
Expected duration	0
Fair value | €	€ 5.11
Plan - September 20, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected dividend yield | €	€ 0.0000
Expected stock price volatility	37.70%
Risk-free interest rate	0.08%
Expected duration	0
Fair value | €	€ 4.77
Bottom of range [member] | Plan - July 13, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - December 29, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - June 14, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - October 12, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - Augustus 22, 2008 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - September 29, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - October 30, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - December 3, 2010 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - April 28, 2011 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	2.35%
Expected duration	0
Fair value | €	€ 1.38
Bottom of range [member] | Plan - February 1, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	2.83%
Expected duration	0
Fair value | €	€ 1.47
Bottom of range [member] | Plan - April 26, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	49.00%
Risk-free interest rate	1.09%
Expected duration	0
Fair value | €	€ 2.15
Bottom of range [member] | Plan - November 6, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	53.40%
Risk-free interest rate	1.54%
Expected duration	0
Fair value | €	€ 3.18
Bottom of range [member] | Plan - January 29, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	52.70%
Risk-free interest rate	1.56%
Expected duration	0
Fair value | €	€ 3.86
Bottom of range [member] | Plan - August 5, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	52.70%
Risk-free interest rate	1.56%
Expected duration	0
Fair value | €	€ 3.86
Bottom of range [member] | Plan - November 25, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	0.91%
Expected duration	0
Fair value | €	€ 3.06
Bottom of range [member] | Plan - April 24, 2014 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Fair value | €	€ 3.71
Bottom of range [member] | Plan - March 16, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - September 14, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - February 24, 2016 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - February 22, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Bottom of range [member] | Plan - September 20, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - July 13, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - December 29, 2006 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - June 14, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - October 12, 2007 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - Augustus 22, 2008 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - September 29, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - October 30, 2009 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - December 3, 2010 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - April 28, 2011 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	2.84%
Expected duration	0
Fair value | €	€ 1.64
Top of range [member] | Plan - February 1, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	3.65%
Expected duration	0
Fair value | €	€ 1.74
Top of range [member] | Plan - April 26, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	56.00%
Risk-free interest rate	1.78%
Expected duration	0
Fair value | €	€ 2.89
Top of range [member] | Plan - November 6, 2012 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	54.00%
Risk-free interest rate	1.88%
Expected duration	0
Fair value | €	€ 4.04
Top of range [member] | Plan - January 29, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	53.80%
Risk-free interest rate	2.08%
Expected duration	0
Fair value | €	€ 4.07
Top of range [member] | Plan - August 5, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected stock price volatility	53.80%
Risk-free interest rate	2.08%
Expected duration	0
Fair value | €	€ 4.07
Top of range [member] | Plan - November 25, 2013 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Risk-free interest rate	1.50%
Expected duration	0
Fair value | €	€ 3.80
Top of range [member] | Plan - April 24, 2014 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Fair value | €	€ 3.92
Top of range [member] | Plan - March 16, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - September 14, 2015 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - February 24, 2016 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - February 22, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0
Top of range [member] | Plan - September 20, 2017 [member]
Disclosure of number and weighted average remaining contractual life of outstanding share options [line items]
Expected duration	0

XML

Financial Liabilities - Additional Information (Detail) € / shares in Units, $ / shares in Units, € in Thousands, $ in Millions					12 Months Ended
	Oct. 27, 2017 shares € / shares	Oct. 26, 2017 € / shares	Oct. 25, 2017 USD ($) $ / shares shares	May 27, 2015 EUR (€)	Dec. 31, 2017 € / shares shares	Dec. 31, 2015 EUR (€)
Disclosure of financial liabilities [line items]
Cash received bond issuance | €						€ 97,185
Conversion price | € / shares	€ 12.66	€ 12.93
Number of shares available for future conversion	7,896,960
Conversion Term [member]
Disclosure of financial liabilities [line items]
Gross proceed from sale of ordinary shares | $			$ 200
Number of ordinary shares sold in public offering			11,430,000
Conversion price | $ / shares			$ 17.50
Underwriter option to purchase shares			1,714,500
Convertibles and Bonds with Warrants Attached [Member]
Disclosure of financial liabilities [line items]
Cash received bond issuance | €				€ 100,000
Bond issued | €				€ 100,000
Debt maturity date					May 27, 2020
Debt maturity period					5 years
Bond coupon rate					3.25%
Conversion price per share | € / shares					€ 12.93
Increase in premium of conversion price per share					26.50%
Original conversion price per share | € / shares					€ 10.2219
Convertible bond, number of shares					7,733,952

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Financial Liabilities - Convertible Bonds And Embedded Derivative (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of financial liabilities [line items]
Embedded derivative	€ 66,454	€ 19,812	€ 54,146
Financial liabilities	170,734	124,668	146,484
Financial liabilities non-current	155,169	104,349	134,828
Convertible Debt Securities [Member]
Disclosure of financial liabilities [line items]
Embedded derivative	66,454	19,812	54,146
Financial liabilities	155,169	104,349	134,828
Financial liabilities non-current	155,169	104,349	134,828
Debt host contract [Member] | Convertible Debt Securities [Member]
Disclosure of financial liabilities [line items]
Embedded derivative	€ 88,715	€ 84,537	€ 80,682

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Financial Liabilities - Borrowing Maturity (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about borrowings [line items]
Borrowings	€ 108,125	€ 111,375	€ 114,625
Not later than one year [member]
Disclosure of detailed information about borrowings [line items]
Borrowings	3,250	3,250	3,250
Later than two years and not later than five years [member]
Disclosure of detailed information about borrowings [line items]
Borrowings	€ 104,875	108,125	111,375
Later than five years [member]
Disclosure of detailed information about borrowings [line items]
Borrowings		€ 0	€ 0

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Financial Liabilities - Borrowings At Fair Value (Detail) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of detailed information about borrowings [abstract]
Closing Balance at December 31, 2016	€ 104,349,000
Financing cash flows	(3,250,000)
Payment of interests	(3,250,000)	€ (3,250,000)	€ (1,625,000)
Non-cash changes	54,070
Effective Intrest Rate	7,427,000
Changes in fair value of derivative	46,642,000
Closing Balance year ended December 31, 2017	€ 155,169,000	€ 104,349,000

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Trade And Other Payables (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of carrying amount and value in use of investments in associates and joint ventures [abstract]
Trade payables	€ 4,761	€ 5,519	€ 4,263
Accruals for invoices to be received	10,804	14,800	7,393
Total trade payables	15,565	20,319	11,656
Social security	852	753	561
Payroll payables	5,705	4,654	4,194
Other liabilities	5	12	1
Total other payables	6,562	5,419	4,756
Total trade and other payables	€ 22,127	€ 25,738	€ 16,412

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Schedule of Deferred Income (Detail) - EUR (€) € in Thousands		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Schedule of Deferred Income [Abstract]
Within 1 year	[1]	€ 21,905	€ 22,118	€ 55,738
In the second to the fifth year	[1]	10,791	11,504	30,385
Total deferred income		€ 32,696	€ 33,622	€ 86,123

[1] This consolidated statement of Financial Position has been restated to present deferred income in current and non-current deferred income. In previously published financial statements, deferred income was presented solely under current liabilities. We refer to note 18.

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Deferred Taxes - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Deferred Tax Assets [Line Items]
Tax rate		33.99%
Total research and development		€ 24,530	€ 19,521	€ 15,755
Bottom of range [member]
Deferred Tax Assets [Line Items]
Total research and development		5 years
Progressive Collection period of tax refund receivable		6 years
Changes in tax rates or tax laws enacted or announced [member]
Deferred Tax Assets [Line Items]
Tax rate	29.58%

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Revenue (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure - Revenue [Abstract]
Upfront fees	€ 24,752	€ 52,311	€ 58,559
Research and development service fees	13,255	13,875	14,403
Milestone payments	17,500	18,400	3,500
License fees & other revenue	55	187	299
Total	€ 55,562	€ 84,773	€ 76,761

XML

Revenue - Additional Information (Detail) € in Thousands, $ in Millions								1 Months Ended	12 Months Ended
	Oct. 12, 2016 EUR (€)	Apr. 21, 2016 EUR (€)	Jan. 29, 2016 EUR (€)	Jul. 22, 2015 EUR (€)	Feb. 03, 2014 EUR (€)	Oct. 02, 2012 EUR (€)	Sep. 07, 2007 EUR (€)	Sep. 30, 2013 USD ($)	Dec. 31, 2017 EUR (€)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)
Disclosure of revenue [line items]
Up-front payment									€ 24,752		€ 52,311	€ 58,559
Milestone payment									€ 17,500		€ 18,400	€ 3,500
Abb Vie [Member]
Disclosure of revenue [line items]
Up-front payment | $										$ 175
Abb Vie [Member] | Top of range [member]
Disclosure of revenue [line items]
Licensing agreement | $								$ 840
Merck & Co [Member]
Disclosure of revenue [line items]
Up-front payment				€ 13,000	€ 20,000	€ 6,500
Research funding						2,000
Milestone payment	€ 1,000				€ 1,700,000
Research term				4 years	3 years
Merck & Co [Member] | Top of range [member]
Disclosure of revenue [line items]
Research funding					€ 10,700
Milestone payment				€ 338,500		€ 429,000
Boehringer Ingelheim [Member]
Disclosure of revenue [line items]
Milestone payment		€ 8,000	€ 8,000				€ 15,000

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Grant Income (Detail) - EUR (€)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amount granted	€ 2,687,000
Grant amount received	2,687,000	€ 3,284,000	€ 2,367,000
Grant amount still to receive	0	601,000	1,518,000
Grant amount recognized as grant income	(31,000)	414,000	779,000
IWT 18 (T-cell recruiting Nanobodies) [Member]
Amount granted	885,597
Amount recognized	885,597
Grant amount received	885,597	886,000	708,000
Grant amount still to receive	0	0	178,000
Grant amount recognized as grant income	€ 0	178,000	0
IWT 18 (T-cell recruiting Nanobodies) [Member] | Grant Start Date [Member]
Grant date	Jun. 01, 2013
IWT 18 (T-cell recruiting Nanobodies) [Member] | Grant End Date [Member]
Grant date	May 31, 2015
IWT 19 (Novel Nanonbody-based therapeutic) [Member]
Amount granted	€ 1,112,926
Amount recognized	1,112,926
Grant amount received	1,112,926	1,674,000	1,116,000
Grant amount still to receive	0	420,000	978,000
Grant amount recognized as grant income	€ (76,000)	120,000	484,000
IWT 19 (Novel Nanonbody-based therapeutic) [Member] | Grant Start Date [Member]
Grant date	Apr. 01, 2014
IWT 19 (Novel Nanonbody-based therapeutic) [Member] | Grant End Date [Member]
Grant date	Mar. 31, 2017
IWT 20 (Bispecific Nanobodies) [member]
Amount granted	€ 445,027
Amount recognized	445,027
Grant amount received	445,027	356,000	267,000
Grant amount still to receive	0	89,000	178,000
Grant amount recognized as grant income	€ 89,000	89,000	75,000
IWT 20 (Bispecific Nanobodies) [member] | Grant Start Date [Member]
Grant date	Jun. 01, 2014
IWT 20 (Bispecific Nanobodies) [member] | Grant End Date [Member]
Grant date	May 31, 2016
IWT 21 (Nanonody-based immunotoxins) [Member]
Amount granted	€ 243,489
Amount recognized	243,489
Grant amount received	243,489	368,000	276,000
Grant amount still to receive	0	92,000	184,000
Grant amount recognized as grant income	€ (44,000)	€ 27,000	€ 220,000
IWT 21 (Nanonody-based immunotoxins) [Member] | Grant Start Date [Member]
Grant date	Jun. 01, 2014
IWT 21 (Nanonody-based immunotoxins) [Member] | Grant End Date [Member]
Grant date	May 31, 2016

XML

Research and Development Expense (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	€ 88,348	€ 98,535	€ 82,099
Depreciation and amortization expenses	2,573	1,780	985
Research and Development Expense	90,920	100,315	83,084
Consumables [member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	5,821	5,916	4,448
Outsourcing [Member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	52,655	65,925	53,897
Patent costs [Member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	2,868	2,134	2,177
Employee Benefits Expenses [Member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	30,426	26,707	22,799
Share Based Compensation [Member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	867	808	751
Other Operating Income (Expense) [Member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	6,746	5,825	5,281
Reduction Withholding Tax for Scientists[member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	(4,119)	(3,702)	(3,381)
Research and Development Incentives [member]
Disclosure Of Research And Development Expenses [line items]
Research and Development Expense	€ (6,916)	€ (5,078)	€ (3,873)

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General and Administrative Expense (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	€ 18,344	€ 13,007	€ 11,055
Depreciation and amortization expenses	461	465	356
General and administrative expenses	18,805	13,472	11,411
Employee Benefits Expenses [Member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	4,217	3,588	3,092
Share Based Compensation [Member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	1,739	1,764	1,069
Executive Committee [Member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	3,787	3,406	3,341
Consultant [member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	5,904	2,414	1,870
Other Operating Income (Expense) [Member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	2,859	2,055	1,887
Reduction Withholding Tax for Scientists[member]
Disclosure of general and administrative expense [Line items]
General and administrative expenses, subtotal	€ (162)	€ (220)	€ (204)

XML

Employee Benefit Expense (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2017 EUR (€) EmployeesEquivalent	Dec. 31, 2016 EUR (€) EmployeesEquivalent	Dec. 31, 2015 EUR (€) EmployeesEquivalent
Salaries, wages and bonuses	€ 24,416	€ 20,986	€ 18,233
Social security	6,336	5,730	4,779
Post-employment benefits	1,839	1,026	881
Share-based compensation expense	2,606	2,572	1,820
Other employment costs	2,089	2,548	1,997
Executive Committee compensation1	3,750	3,406	3,341
Reduction withholding tax for scientists	(4,282)	(3,922)	(3,585)
Total	€ 36,755	€ 32,346	€ 27,466
Average FTE | EmployeesEquivalent	419	364	325
Executive Committee [Member]
Average FTE | EmployeesEquivalent	7	7	8
R&D personnel [Member]
Average FTE | EmployeesEquivalent	363	321	284
General and administrative Personnel [member]
Average FTE | EmployeesEquivalent	49	36	33

XML

Operating Lease - Additional Information (Detail) - Bio-Versneller NV [Member] € in Thousands			1 Months Ended	12 Months Ended
	May 01, 2016 m²	Jan. 01, 2016 m²	Jun. 30, 2010 m²	Dec. 31, 2017 EUR (€)	Dec. 31, 2016 EUR (€)	Dec. 31, 2015 EUR (€)
Disclosure of finance lease and operating lease by lessee [line items]
Lease term	5 years	3 years
Minimum lease payments | €				€ 3,681	€ 3,487	€ 3,310
Agreement termination notice period		2 years
Area of land | m²	970.68	8,800	8,000
Automobile business [Member]
Disclosure of finance lease and operating lease by lessee [line items]
Lease term				4 years
Office furniture and other equipment [member]
Disclosure of finance lease and operating lease by lessee [line items]
Lease term				5 years

XML

Non concealable Operating Lease (Detail) - EUR (€) € in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating lease commitments	€ 13,500
Not later than one year [member]
Operating lease commitments	3,902	€ 3,853	€ 3,277
Later than two years and not later than five years [member]
Operating lease commitments	9,557	12,598	4,750
After five years [Member]
Operating lease commitments	€ 0	€ 0	€ 0

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Financial Income Expense (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financial income
Interest income on financial assets	€ 49	€ 298	€ 1,101
Financial income related to convertible bond Changes in fair value of embedded derivative		34,334
Other financial income	400	129	667
Total	449	34,761	1,768
Financial expenses
Interest charges on financial liabilities Financial expenses related to convertible bond Changes in fair value of embedded derivative	(46,642)		(34,646)
Interest expenses on convertible bond	(7,427)	(7,105)	(4,074)
Financing charges			(549)
Other financial expenses	(717)	(143)	(91)
Total	54,787	7,248	39,360
Net financial result	(54,337)	€ 27,513	€ (37,592)
Scenario, Adjustment [Member]
Financial expenses
Total	€ (54,786)

XML

Financial Income Expense - Additional Information (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Unrealized Foreign Exchange Losses [Member]
Foreign exchange losses	€ 19	€ 50
Foreign exchange gains	373	164
Realized Foreign Exchange Gains (Losses) [Member]
Foreign exchange losses	€ 331	92
Foreign exchange gains		€ 0

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Income Tax Expense (Detail) - EUR (€) € in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Major components of tax expense (income) [abstract]
Loss of the year	€ (108,532)	€ (1,087)	€ (54,547)
Income taxes calculated at 33.99%	36,890	369	18,541
Effect of income that is exempt from taxation	368	490	558
Effect of expenses that are not deductible in determining taxable profit	(248)	(219)	(199)
Effect of unused tax losses and tax offsets not recognised as deferred tax assets	(37,010)	(641)	(18,899)
Effective income taxes	€ 0	€ 0	€ 0

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Income Tax Expense (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2017
Major components of tax expense (income) [abstract]
Income tax rate, applicable	33.99%

XML

Loss Per Share (Detail) - EUR (€) € / shares in Units, € in Thousands, shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic loss per share
Loss of the year	€ (108,532)	€ (1,087)	€ (54,547)
Weighted average number of shares outstanding	62,322,875	58,499,545	54,382,147
Basic loss per share	€ (1.74)	€ (0.02)	€ (1.00)
Diluted loss per share
Loss of the year as used for basic loss per share	€ (108,532)	€ (1,087)	€ (54,547)
Adjustments to earnings relating to convertible bond	0	(27,229)	0
Loss of the year	€ (108,532)	€ (28,316)	€ (54,547)
Weighted average number of shares outstanding	62,322,875	58,499,545	54,382,147
Adjustments to number of shares relating to convertible bond	0	7,733,952	0
Weighted average number of shares outstanding after dilution effect	62,322,875	66,233,497	54,382,147
Diluted loss per share	€ (1.74)	€ (0.43)	€ (1.00)

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Commitments Lease Agreements - Additional Information (Detail) € in Millions			1 Months Ended	12 Months Ended
	May 01, 2016 m²	Jan. 01, 2016 m²	Jun. 30, 2010 m²	Dec. 31, 2017 EUR (€) m²	Jan. 31, 2012 EUR (€)	Dec. 31, 2016 EUR (€)
Disclosure of finance lease and operating lease by lessee [line items]
Bank Guarantees				€ 1.6
Purchase commitment,term				The Company has entered into numerous agreements with universities, medical centers and external researchers for research and development work and for the validation of the Company's technology and products. These agreements typically have durations of one to three years. The Company must pay fixed and variable fees to the collaborators and in exchange receives access and rights to the result of the work
Purchase commitment				€ 75.9
Land and buildings [member] | Housing of llamas [Member]
Disclosure of finance lease and operating lease by lessee [line items]
Area of land | m²				25,322
Not later than one year [member]
Disclosure of finance lease and operating lease by lessee [line items]
Purchase commitment				€ 33.2
Incubatie [Member]
Disclosure of finance lease and operating lease by lessee [line items]
Area of land | m²				42
lease description				In 2017, the Company also extended its lease agreement with Incubatie- en Innovatiecentrum Universiteit Gent NV, or IIC UGent, for a storage space of 42 square meters also in Ghent/Zwijnaarde, Belgium.
Lease term				3 years
Bio-Versneller NV [Member]
Disclosure of finance lease and operating lease by lessee [line items]
Lease expendable term			8 years
Area of land | m²	970.68	8,800	8,000
lease description	The Company has also signed a contract with Devgen nv, who has provided the Company with 970.68 m of laboratory facilities within the Technologiepark 30 as from May 2016, with an initial term of five years which can be extended.			The Company has signed contracts with Bio-Versneller NV, who has provided the Company with 8,000 m of laboratory and office facilities within the Technologiepark since June 2010. The initial term of the contract was an extendable period of eight years.
Pledge granted under lease agreement					€ 1.7	€ 0.0
Pledge granted under lease agreement,recognition period					5 years
Agreement termination notice period		2 years
Lease term	5 years	3 years

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Remuneration Key Management and Non-executive Directors (Detail) € in Thousands	12 Months Ended
	Dec. 31, 2017 EUR (€) Management_Member shares	Dec. 31, 2016 EUR (€) Management_Member shares	Dec. 31, 2015 EUR (€) Management_Member shares	Sep. 20, 2017 shares	Feb. 22, 2017 shares	Sep. 09, 2016 shares	Feb. 24, 2016 shares	Sep. 14, 2015 shares
Disclosure of transactions between related parties [line items]
Number of warrants granted (in units) | shares				629,000	527,061	0	429,479	233,000
Key management [member]
Disclosure of transactions between related parties [line items]
Number of management members | Management_Member	7	7	8
Short-term employee benefits (salaries, social security, bonuses, lunch vouchers)	€ 2,580	€ 2,394	€ 2,295
Post-employment benefits (group insurance)	284	183	166
Share-based compensation expense	1,512	1,547	834
Other employee benefits	129	130	124
Management fees	398	338	451
Retribution	(27)	(32)	(31)
Total	€ 4,875	€ 4,560	€ 3,839
Number of warrants granted (in units) | shares	433,440	365,844	293,311
Cumulative outstanding warrants (in units) | shares	1,507,149	1,824,259	1,744,645
Shares owned (in units) | shares	577,805	402,805	205,805
Non Executive Directors [member]
Disclosure of transactions between related parties [line items]
Share-based compensation expense	€ 1	€ 13	€ 41
Management fees	360	363	305
Total	€ 361	€ 376	€ 346
Cumulative outstanding warrants (in units) | shares	64,590	68,430	74,595
Non-vested warrants | shares		2,432	22,831
Shares owned (in units) | shares	31,434	31,165	25,000

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Events After the Reporting Date - Additional Information (Detail) - EUR (€) € / shares in Units, € in Millions	Feb. 16, 2018	Jan. 28, 2018	Oct. 27, 2017	Oct. 26, 2017
Disclosure of Events After Reporting Period [Line Items]
Share price			€ 12.66	€ 12.93
Events After Reporting Period [Member] | Sanofi [member]
Disclosure of Events After Reporting Period [Line Items]
income from research collaboration agreement	€ 13
Convertible bonds [member] | Events After Reporting Period [Member]
Disclosure of Events After Reporting Period [Line Items]
Share price		€ 45
Proceeds from conversion of convertible securities		€ 3,900