The Company has entered into collaboration and license agreements with various pharmaceutical and biotechnology companies. As described in Note 2, on January 1, 2019, the Company adopted ASC 606, Revenue from Contracts with Customers, which supersedes the guidance in ASC 605, Revenue Recognition. The Company recognized revenue under ASC 606 for the three and six months ended June 30, 2019 and under ASC 605 for the three and six months ended June 30, 2018. In accordance with the collaboration agreements, the Company recognized revenue as follows:

	Three Months Ended June 30,				Six Months Ended June 30,
	2019		2018		2019		2018
	(dollars in thousands)				(dollars in thousands)
Celgene Corporation (“Celgene”) (1)	$	1,670	$	2,835	$	3,245	$	6,919
Merck Sharp & Dohme Corporation (“Merck”)—related party		5,497		–		10,132		–
Merck KGaA, Darmstadt, Germany (operating in the United States and Canada under the name “EMD Serono”)		3,358		1,967		5,496		3,676
SutroVax—related party		–		902		281		902
Total revenue	$	10,525	$	5,704	$	19,154	$	11,497

(1)	Celgene was a related party during the three and six months ended June 30, 2018 as it held more than 10% of the Company’s common stock for the periods presented until the IPO closed on October 1, 2018.

The following table presents the changes in the Company’s deferred revenue balance from collaboration agreements during the six months ended June 30, 2019:

	Six Months Ended June 30, 2019
	(in thousands)
Deferred revenue—December 31, 2018	$	66,173
Transition adjustment related to adoption of ASC 606		(10,327	)
Additions to deferred revenue		2,074
Recognition of revenue in current period		(10,963	)
Deferred revenue—June 30, 2019	$	46,957

The Company’s balance of deferred revenue contains the transaction price from collaboration agreements allocated to performance obligations which are partially unsatisfied. The Company expects to recognize approximately $21.4 million of deferred revenue over the next twelve months.

There have been no material changes to the Company’s collaboration agreements in the three and six months ended June 30, 2019, except as described below.

In September 2014, the Company signed a Collaboration and License Agreement with Celgene to discover and develop bispecific antibodies and/or antibody-drug conjugates (“ADCs”), focused primarily on the field of immuno-oncology, using the Company’s proprietary integrated cell-free protein synthesis platform, XpressCF™.

Upon signing the Celgene Agreement, the Company received an upfront, nonrefundable payment totaling $83.1 million.

In March 2015, the Company received a $15.0 million contingent payment (“March 2015 payment”) from Celgene that provided Celgene a right to access certain of the Company’s technology for use in conjunction with certain Celgene intellectual property. In June 2016, the Company received a $25.0 million milestone (“June 2016 payment”) upon completion of certain preclinical activities. Additionally, in June 2016, the Company earned a $10.0 million substantive milestone for certain manufacturing accomplishments.

In August 2017, the Company received an option fee payment of $12.5 million. In September 2017, the Company earned a $10.0 million milestone for certain manufacturing accomplishments, which payment was received from Celgene in October 2017. In December 2018, the Company earned a $10.0 million milestone for certain manufacturing accomplishments, which payment was received from Celgene in the same month.

In August 2017, the Company entered into an amended and restated collaboration and license agreement with Celgene to refocus the collaboration on four programs that are advancing through preclinical development, including an ADC program targeting B cell maturation antigen (“BCMA ADC”).

In May 2019, the U.S. Food and Drug Administration cleared the investigational new drug (“IND”) application for the BCMA ADC, which was discovered and manufactured by the Company and is the first collaboration program IND. Celgene has worldwide development and commercialization rights with respect to the BCMA ADC. The Company will continue to be responsible for clinical supply manufacturing and certain development services for the BCMA ADC and is eligible to receive from Celgene aggregate development and regulatory contingent payments of up to $275.0 million, if approved in multiple indications, and tiered royalties ranging from mid to high single digit percentages on worldwide sales of any resulting commercial products.

With respect to the remaining three collaboration programs (BCMA-CD3, PD1-LAG3 and PD1-TIM3), during the second quarter of 2019 Celgene notified the Company that it decided not to exercise the option to acquire U.S. clinical development and commercialization rights to a second collaboration program. Therefore, Celgene was not required to pay the Company the $12.5 million option maintenance fee that would have been due upon IND clearance for the first collaboration program, as described above. Consequently, the U.S. clinical development and commercialization rights to the other three collaboration programs remain owned by the Company, without any further option to Celgene. For any products resulting from these three collaboration programs, Celgene will own ex-U.S. development and commercialization rights and will be obligated to pay the Company development and regulatory contingent payments and tiered royalties ranging from mid to high single digit percentages.

The contingent payments under the Celgene Agreement are not considered to be substantive milestones because the receipt of such payments is based solely on the performance of Celgene.

The Company has received and will be eligible to receive financial support for research and development services assigned to the Company by Celgene, based on an agreed-upon level of FTE personnel effort and related reimbursement rate, which will be recognized as revenue as the related reimbursable activities approved by Celgene and the Company are performed by the Company.

Celgene may terminate the Celgene Agreement at any time with 120 days’ prior written notice. Either the Company or Celgene has the right to terminate the Celgene Agreement based on the other party’s uncured material breach, challenge of the validity and enforceability of intellectual property, or bankruptcy.

In accounting for this arrangement under ASC 606, applying the practical expedients, the Celgene Agreement was treated as a single arrangement that had been modified in 2017.

Given the modification of the Celgene Agreement in 2017, the Company determined that the remaining deferred revenue balance of $8.2 million as of the date of the modification, related to certain prior Celgene payments to the Company, together with the $12.5 million option fee payment received in August 2017, would comprise the transaction price of $20.7 million to be allocated on a relative basis among the Company’s performance obligations based on the Company’s best estimate of each SSP or fair value. The Company identified the three performance obligations relating to the Celgene Agreement as: (1) access by Celgene to worldwide development and commercialization rights on the first collaboration program to achieve IND clearance; (2) the Company’s estimated future services on the collaboration Joint Steering Committee (“JSC”); and (3) Celgene’s use of certain technology and the option to acquire worldwide development and commercialization rights to a second collaboration program.

Based on its estimated SSP, relative to the total estimated SSP values of all identified performance obligations, the portion of the transaction price allocated to the first performance obligation was $8.2 million, which performance obligation was satisfied as of the modification date of the Celgene Agreement, as the BCMA ADC program was the most advanced of the four collaboration programs and estimated by the Company to be the one for which Celgene would first achieve IND clearance and gain worldwide development and commercialization rights. The second and third performance obligations identified above were unsatisfied as of the modification date of the Celgene Agreement. The Company determined the portion of the transaction price to be allocated to the JSC performance obligation was $0.2 million. Revenue related to such performance obligation will be recognized by the Company over the estimated period during which it will perform its JSC services. The Company determined that the portion of the transaction price to be allocated to the third performance obligation, which provided Celgene with an option to acquire worldwide development and commercialization rights to a second collaboration program, was $12.3 million. Although Celgene decided not to exercise this option, the Company still has the continuing performance obligation to provide Celgene access to the Company’s technology. As such, the Company’s revenue related to such performance obligation will continue to be recognized over the period from August 2017 through September 2020, the estimated term of the use of the technology.

Upon the adoption of ASC 606 on January 1, 2019, the Company recorded a $4.5 million adjustment to decrease its deferred revenue for performance obligations that were satisfied in prior periods, with the corresponding adjustment being a reduction to the Company’s accumulated deficit. For the three and six months ended June 30, 2019, the Company recognized approximately $1.1 million and $2.2 million, respectively, of revenue under ASC 606. For the three and six months ended June 30, 2018, the Company recognized approximately $1.2 million and $3.4 million, respectively, of revenue under ASC 605.

As of June 30, 2019 and December 31, 2018, there was $7.0 million and $11.4 million, respectively, of deferred revenue related to payments received by the Company under the Celgene Agreements. As of June 30, 2019 and December 31, 2018, the Company had $0.1 million and $0.6 million, respectively, of receivables from Celgene related to the Celgene Agreement, which are included in accounts receivable on the balance sheet.

In March 2018, the Company entered into a Master Development and Clinical Manufacturing Services Agreement (the “2018 Celgene Master Services Agreement”) with Celgene, wherein Celgene requested the Company to provide development, manufacturing and supply chain management services, including clinical product supply. The consideration for the services is based on an agreed-upon level of FTE personnel effort and related reimbursement rate in addition to agreed-upon pricing for the clinical product supply.

Upon adoption of ASC 606 on January 1, 2019, this was deemed a modification of the arrangement and the consideration terms were at fair value and materials are to be provided on an as agreed upon basis. Accordingly, the Company will recognize revenue upon the performance of such services.

For the three and six months ended June 30, 2019, the Company earned $0.6 million and $1.0 million, respectively, under the 2018 Celgene Master Services Agreement. For the three and six months ended June 30, 2018, the Company earned $1.7 million and $3.6 million, respectively, under the 2018 Celgene Master Services Agreement.

As of June 30, 2019 and December 31, 2018, the Company had $ 2.6 million and zero, respectively, of receivables from Celgene related to the Celgene Master Services Agreement, which are included in accounts receivable on the balance sheet.

In July 2018, the Company entered into an Exclusive Patent License and Research Collaboration Agreement (the “2018 Merck Agreement”) with Merck, a related party of the Company, to jointly develop up to three research programs focusing on cytokine derivatives for cancer and autoimmune disorders.

Under the 2018 Merck Agreement, the Company received from Merck a non-refundable, non-creditable, upfront payment of $60.0 million in August 2018 for access to the Company’s technology and the identification and preclinical research and development of two target programs, with an option for Merck to engage the Company to continue these activities for a third program upon the payment of an additional amount. Under ASC 606, the Company identified the five performance obligations under the 2018 Merck Agreement as: (1) access to certain intellectual property rights; (2) performance of services related to the first target program; (3) performance of services related to the second target program; (4) the Company’s estimated future services on the collaboration JSC; and (5) a material right pertaining to the performance of services related to a contingent third target program upon the payment of an additional amount. The transaction price of $60.0 million was allocated among the performance obligations using the Company’s best estimate of SSP for each of the associated performance obligations. Based on its estimated SSP, relative to the estimated total SSP values of all identified performance obligations, the portion of the transaction price allocated to the first performance obligation was $7.3 million. It was determined that such performance obligation was satisfied as of the effective date of the 2018 Merck Agreement, and accordingly revenue associated with this performance obligation would, pursuant to ASC 606, have been recorded on the effective date of the Merck Agreement. Revenue allocated to the first and second target programs, which totaled $47.1 million is being recognized on a proportion of performance basis, using the FTE cost as the basis of measurement, with such performance expected to occur over an estimated service period of three years for each target program. As it pertains to the JSC performance obligation, the revenue allocated to such performance obligation was $0.7 million, which is being recognized as revenue on a proportion of performance basis using FTE cost as the basis, and such effort is expected to be incurred on a relatively consistent basis throughout the term of the 2018 Merck Agreement. The Company allocated $4.9 million of the transaction price to the material right associated with the contingent third program. Recognition of the $4.9 million as revenue will begin upon commencement of the third program or upon the determination that the contingent third target program is no longer a performance obligation.

Additionally, under ASC 606, the Company determined there was a financing component associated with the $60.0 million upfront payment, and has calculated total interest of $7.2 million as of June 30, 2019 on the unearned revenue portion beyond one year from the effective date of the agreement, which amount is expected to be recognized as revenue over the estimated service period for the first and second target programs.

For the three and six months ended June 30, 2019, the Company recognized revenue of $3.8 million and $6.7 million, respectively, associated with the $60.0 million upfront payment, $0.8 million and $1.7 million, respectively, related to the interest component described above, and $0.9 million and $1.7 million, respectively, for FTE funding provided by Merck.

Upon adoption of ASC 606 on January 1, 2019, the Company recorded a $6.3 million adjustment to decrease its deferred revenue for performance obligations that were satisfied in prior periods, with the corresponding adjustment being a reduction to the Company’s accumulated deficit.

As of June 30, 2019 and December 31, 2018, there was $39.9 million and $53.0 million, respectively, of deferred revenue related to the transaction price under the 2018 Merck Agreement. As of both June 30, 2019 and December 31, 2018, the Company had $0.9 million of receivables from Merck related to the 2018 Merck Agreement, which are included in accounts receivable on the balance sheet.

The Company is also eligible to receive aggregate milestone payments of up to $1.6 billion, assuming the development and sale of all therapeutic candidates and all possible indications identified under the collaboration. If one or more products from each of the target programs are developed for non-oncology or a single indication, the Company will be eligible for reduced aggregate milestone payments. In addition, the Company is eligible to receive tiered royalties ranging from mid-single digit to low teen percentages on the worldwide sales of any commercial products that may result from the collaboration.

Merck may terminate the 2018 Merck Agreement at any time with 60 days’ prior written notice. Either the Company or Merck has the right to terminate the 2018 Merck Agreement based on the other party’s uncured material breach or bankruptcy.

During 2018, Merck purchased 74,794,315 shares of the Company’s Series E redeemable convertible preferred stock at a price per share of $0.2674, resulting in gross proceeds of $20.0 million. In a private placement concurrent with the Company’s IPO, which was completed on October 1, 2018, Merck purchased 666,666 shares of common stock at a price per share of $15.00, resulting in proceeds of approximately $10.0 million. As a result of the investments in the Company’s equity, Merck is a related party.

The Company signed a Collaboration Agreement and a License Agreement with EMD Serono in May 2014 and September 2014, respectively, which were entered into in contemplation of each other and therefore treated as a single agreement for accounting purposes. The Collaboration Agreement was subsumed into the License Agreement (the “MDA Agreement”), which agreement is to develop ADCs for multiple cancer targets.

Upon signing the Collaboration Agreement, the Company received an upfront, nonrefundable, non-creditable payment totaling $10.0 million. Upon signing the MDA Agreement, the Company received an additional upfront, nonrefundable payment totaling $10.0 million and will receive financial support for research and development services to be provided by the Company, based on an agreed-upon level of FTE personnel effort and related reimbursement rate.

The Company is eligible to receive up to $52.5 million for each product developed under the MDA Agreement, primarily from pre-commercial contingent payments. In addition, the Company is eligible to receive tiered royalties ranging from low-to-mid single digit percentages, along with certain additional one-time royalties, on worldwide sales of any commercial products that may result from the MDA Agreement. The MDA Agreement term expires on a product-by-product and country-by-country basis. Upon expiration, EMD Serono will have a fully paid-up, royalty-free, perpetual, and irrevocable non-exclusive license, with the right to grant sublicenses, under certain Company intellectual property rights. EMD Serono may terminate the MDA Agreement at any time with 90 days’ prior written notice or upon the inability of the Company to provide EMD Serono access to a specified number of cancer drug targets. Either the Company or EMD Serono has the right to terminate the MDA Agreement based on the other party’s uncured material breach or bankruptcy.

Upon adoption of ASC 606 on January 1, 2019, the Company identified a single performance obligation under the MDA Agreement, which consists of the technology license, research and development activities and JSC participation over the estimated period of the agreement, as each are interrelated and not distinct within the overall context of the agreement. The transaction price of $20.0 million is being recognized on a proportion of performance basis, using the FTE cost as the basis of measurement, with such performance occurring over the estimated service period of the agreement, from June 2014 through May 2019.

The Company recorded a $0.6 million adjustment to increase its deferred revenue for performance obligations that were unsatisfied in prior periods, with the corresponding adjustment being an increase to the Company’s accumulated deficit.

For the three and six months ended June 30, 2019, the Company earned $3.4 million and $5.5 million, respectively, from EMD Serono, of which $1.5 million and $1.5 million, respectively, are from a new supply agreement. For the three and six months ended June 30, 2018, the Company earned $2.0 million and $3.7 million, respectively, under the MDA Agreement. As of June 30, 2019 and December 31, 2018, there was zero and $1.7 million, respectively, of deferred revenue related to payments received by the Company under the MDA Agreement. As of June 30, 2019 and December 31, 2018, the Company had $2.8 million and $0.9 million, respectively, of receivables from EMD Serono, which are included in accounts receivable on the balance sheet.

In May 2018, the Company entered into a Supply Agreement (the “Supply Agreement”) with SutroVax, Inc., (“SutroVax”), wherein SutroVax engaged the Company to supply extracts and custom reagents, as requested by SutroVax. The pricing is based on an agreed upon cost plus arrangement. For the three and six months ended June 30, 2019, the Company recognized revenue of zero and $0.3 million under the Supply Agreement. As of June 30, 2019 and December 31, 2018, the Company had $14,000 and $49,000 in receivables, respectively, from SutroVax related to the Supply Agreement, which is included in accounts receivable on the balance sheet.

Upon adoption of ASC 606 on January 1, 2019, as the Company has a right to consideration from SutroVax in an amount that corresponds directly with the value of the Company’s supplied extracts and custom reagents, the Company’s sales of extracts and custom reagents in discrete unit form are recognized as revenue at the time when such supplies are shipped to SutroVax, in line with the “right to invoice” practical expedient in ASC 606.

The Company has not received any returns to date and believes that returns of its products will continue to be minimal. As such, the Company does not record any reserve for the returns but will continue to evaluate the need for a reserve each reporting period.