LICENSE AND COLLABORATION AGREEMENTS	12 Months Ended
Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
LICENSE AND COLLABORATION AGREEMENTS	3. LICENSE AND COLLABORATION AGREEMENTS Lysogene S.A. On October 15, 2018, the Company entered into a license and collaboration agreement (the “Lysogene License and Collaboration Agreement”) for developing and commercializing LYS-SAF302, a gene therapy to treat Mucopolysaccharidosis type IIIA (“MPS IIIA”) with Lysogene S.A. (“Lysogene”). Under the terms of the Lysogene License and Collaboration Agreement, Lysogene will be responsible for completion of the pivotal trial, which commenced in the fourth quarter of 2018. The Company will have exclusive rights to commercialize LYS-SAF302 in the U.S. and all territories outside of Europe. Lysogene will retain exclusive commercial rights to LYS-SAF302 in Europe. The Company will be responsible for global manufacturing of LYS-SAF302 and will supply drug products to Lysogene for Europe. Lysogene also granted the Company certain option rights to an additional central nervous system targeted gene therapy candidate. Concurrently with the execution of the Lysogene License and Collaboration Agreement, the Company entered into an equity investment agreement with Lysogene. Under the equity investment agreement, the Company purchased 950,606 shares of common stock issued by Lysogene, representing 8% of the outstanding equity of Lysogene at the time of the transaction. The Company considered whether it would have to consolidate the operations of Lysogene and concluded that, while Lysogene is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Lysogene. As a result of execution of the agreements, the Company made a payment of $28.0 million to Lysogene related to the up-front license fee, the option fee, the equity investment and reimbursement of certain development activities. Additionally, the Company may be liable for up to approximately $102.8 million in development, regulatory and sales milestones associated with the Lysogene License and Collaboration Agreement. Furthermore, the Company may be required to make tiered royalty payments based on net sales of the LYS-SAF302 product subsequent to its commercialization. Of the $28.0 million payment to Lysogene, $1.9 million was allocated to the equity investment in Lysogene, based on the closing price of Lysogene’s common stock traded on the Euronext Paris Exchange on October 12, 2018, and was recorded as an other non-current asset. The remaining $26.1 million was allocated to the up-front license fee, the option fee, and reimbursement of certain development activities, and represents rights to potential future benefits associated with ongoing research and development activities that have no alternative future use. Accordingly, this amount was recorded as research and development expense as incurred. As of December 31, 2018, one development milestone was deemed as probable of being achieved. As a result, the Company recorded an accrued expense of $18.7 million which was classified as research and development expense. Changes in the fair value of the equity investment in Lysogene are recorded to other income and expense in the Company’s consolidated statements of operations and other comprehensive loss. As of December 31, 2018, the Company recognized a loss of $0.2 million related to the change in fair market value of the equity investment. Lacerta Therapeutics On August 8, 2018 (the “Effective Date”), the Company entered into a License, Development and Option Agreement (the “Lacerta License Agreement”) with Lacerta Therapeutics, Inc. (“Lacerta”). Pursuant to the Lacerta License Agreement, the Company licensed exclusive worldwide rights to develop, manufacture and commercialize a pre-clinical Pompe product candidate (the “Pompe License”). Lacerta also granted the Company exclusive options to enter into exclusive license agreements to develop, manufacture and commercialize other gene therapy product candidates for Sanfilipo syndrome and L-Amino Acid Decarboxylase Deficiency for additional consideration of $42.0 million (collectively, the “Options”) when (and if) the Options are exercised. Additionally, the Company may be liable for up to approximately $44.0 million in development, regulatory and sales milestones associated with the Pompe License and may be required to make a high-single-digit royalty payments based on net sales of the Pompe product subsequent to its commercialization. Concurrently with the execution of the Lacerta License Agreement, the Company entered into a Series A Preferred Stock Purchase Agreement (the “Purchase Agreement”) with Lacerta. Under the Purchase Agreement, the Company purchased approximately 4.5 million shares of Series A preferred stock issued by Lacerta. The Company considered whether it would have to consolidate the operations of Lacerta and concluded that, while Lacerta is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Lacerta. The Company made an up-front payment of $38.0 million to Lacerta in consideration of both the Lacerta License Agreement and the Purchase Agreement. This payment was allocated to the fair value of the Series A preferred stock investment, the Pompe License and the Options based on their respective relative fair values on the Effective Date. The fair value of the Options were determined using an option pricing model, whereas the Series A preferred stock investment was determined using a cost approach corroborated by the Black-Scholes option pricing model. The fair value of the Pompe License was determined by the income approach, using a discounted cash flow model based on projections of future cash flows that will arise from the Pompe product candidate. Accordingly: (i) $30.0 million was allocated to the Series A preferred stock investment, (ii) $8.0 million was allocated to the Pompe License, and (iii) no amount was allocated to the Options as they are far out of money and were determined to have a fair value of zero. The Series A preferred stock investment was initially measured at cost and classified as an other non-current asset in the accompanying consolidated balance sheets. Subsequently, changes in the carrying value of the investment will be reported as a component of earnings whenever there are observable price changes in orderly transactions for identical or similar investments of Lacerta in the future. The amount allocated to the Pompe License represents rights to potential future benefits associated with ongoing research and development activities that have no alternative future use. Accordingly, this amount has been recorded as research and development expense in the accompanying consolidated statements of operations and comprehensive loss for the year ended December 31, 2018. As of December 31, 2018, no development milestones were deemed as probable of being achieved and, accordingly, no research and development expense was recognized related to these development milestones. Myonexus Therapeutics On May 3, 2018, the Company entered into a Warrant to Purchase Common Stock Agreement (“Warrant Agreement”) with Myonexus Therapeutics, Inc. (“Myonexus”). Pursuant to the terms of the Warrant Agreement, the Company made an up-front payment of $60.0 million to purchase an exclusive option to acquire Myonexus for $200.0 million plus sales-related and regulatory-related contingent payments. Prior to the exercise of the option to acquire Myonexus, the Company may be required to make additional development milestone payments to Myonexus of up to $45.0 million over an approximately two-year evaluation period. The Company considered whether it would have to consolidate the operations of Myonexus and concluded that, while Myonexus is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Myonexus. As of December 31, 2018, the Company made an up-front payment of $60.0 million and milestone payments totaling $20.0 million to Myonexus corresponding to execution of the Warrant Agreement and achievement of two development milestones, respectively. Additionally, the third development milestone for $5.0 million was deemed probable of being achieved as of December 31, 2018, and has been recorded as an accrued expense. Prior to regulatory approval, all consideration paid to Myonexus represents rights to potential future benefits associated with Myonexus’s ongoing research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the Company recorded $85.0 million for the year ended December 31, 2018 as research and development expense in the accompanying consolidated statements of operations and comprehensive loss. Nationwide Children’s Hospital On December 29, 2016, the Company entered into an exclusive option agreement with Nationwide Children’s Hospital (“Nationwide”) from which the Company obtained an exclusive right to acquire a worldwide license of the micro-dystrophin gene therapy technology for DMD and Becker muscular dystrophy. On October 8, 2018, the Company exercised the option and entered into a license agreement with Nationwide (“Nationwide License Agreement”). Pursuant to the Nationwide License Agreement, the Company licensed exclusive worldwide rights to develop, manufacture and commercialize micro-dystrophin gene therapy product candidates. Under the agreement, the Company made an up-front payment of $1.0 million to Nationwide, which was recorded as research and development expense in the accompanying consolidated statements of operations and comprehensive loss for the year ended December 31, 2018. Additionally, the Company may be required to make up to $29.0 million in development, regulatory and sale milestone payments per micro-dystrophin product and a low-single-digit royalty payments based on net sales of the micro-dystrophin products upon commercialization. As of December 31, 2018, no development milestones were deemed as probable of being achieved and, accordingly, no research and development expense was recognized related to these development milestones. BioMarin Pharmaceutical, Inc. In July 2017, the Company and UWA entered into a settlement agreement with BioMarin Leiden Holding BV, its subsidiaries BioMarin Nederlands BV and BioMarin Technologies BV (collectively, “BioMarin”). On the same day, the Company entered into a license agreement with BioMarin and Academisch Ziekenhuis Leiden (“AZL”) (collectively with the Company, UWA and BioMarin, the “Settlement Parties”). Under these agreements, BioMarin agreed to provide the Company with an exclusive license to certain intellectual property with an option to convert the exclusive license into a co-exclusive license and the Settlement Parties agreed to stop most existing efforts to continue with ongoing litigation and opposition and other administrative proceedings concerning BioMarin’s intellectual property. Under terms of the agreements, the Company agreed to make total up-front payments of $35.0 million upon execution of the agreements, consisting of $20.0 million under the settlement agreement and $15.0 million under the license agreement. Additionally, the Company may be liable for up to approximately $65.0 million in regulatory and sales milestones for eteplirsen as well as exon 45 and exon 53 skipping product candidates. BioMarin will also be eligible to receive royalty payments, ranging from 4% - 8%, for exon 51 skipping products, exon 45 skipping products and exon 53 skipping products. The royalty terms under the license agreement will expire in December 2023 in the U.S. and September 2024 in the EU. In connection with the above agreements, in July 2017, the Company made a cash payment of $35.0 million to BioMarin. Of this amount, $6.6 million was recorded as an intangible asset on the Company’s consolidated balance sheets. The remaining amount of $28.4 million was expensed as incurred as EXONDYS 51 settlement and license charges in the Company’s consolidated statements of operations and comprehensive loss. The $6.6 million intangible asset represents the fair value of the U.S. license to BioMarin’s intellectual property related to EXONDYS 51, which was determined by an income-based approach, and is being amortized on a straight-line basis over the remaining life of the patent. For the year ended December 31, 2018, the Company recognized intangible asset amortization expense and royalty expense of approximately $0.9 million and $15.1 million, respectively. For the year ended December 31, 2017, the Company recognized intangible asset amortization expense and royalty expense of approximately $1.0 million and $4.7 million, respectively. The royalties are included in cost of sales in the Company’s consolidated statements of operations and comprehensive loss. As of December 31, 2018, no regulatory or sales milestones were deemed as probable of being achieved and, accordingly, no additional in-licensed rights were recognized related to these milestones. Summit (Oxford) Ltd. In October 2016, the Company entered into an exclusive Collaboration and License Agreement (the “Summit Collaboration Agreement”) with Summit which grants the Company the exclusive right to commercialize products in Summit’s utrophin modulator pipeline in the EU, Switzerland, Norway, Iceland, Turkey and the Commonwealth of Independent States (the “Licensed Territory”). Under the terms of the Summit Collaboration Agreement, the Company made an up-front payment of $40.0 million to Summit, with additional payments of up to $192.0 million based on achievement of certain development and regulatory milestones for ezutromid, a Summit product candidate in its utrophin modulator pipeline. For each of Summit’s future generation small molecule utrophin modulators, the Company may be required to make up to $290.0 million in development and regulatory milestone payments. Additionally, on a product-by-product basis, the Company may be required to make up to $330.0 million in sales milestone payments. The Summit Collaboration Agreement also grants the Company an option to expand the Licensed Territory (“Option Territory”). If the Company exercises this option, it will be liable for a one-time $10.0 million option fee as well as up to $7.0 million in regulatory milestone payments. For each licensed product in the Option Territory, the Company may be liable for up to $82.5 million in sales milestone payments. Additionally, the Company may be required to make tiered royalty payments ranging from a low to high teens percentage of net sales on a product-by-product basis in the Licensed Territory. Under the Summit Collaboration Agreement, a joint steering committee was established to plan, monitor and coordinate future development activities for ezutromid and future generation small molecule utrophin modulators. Summit was solely responsible for all research and development costs for the licensed products until December 31, 2017. Thereafter, Summit will be responsible for 55.0% of the budgeted research and development costs related to the licensed products in the Licensed Territory, and the Company will be responsible for 45.0% of such costs. Any costs in excess of 110.0% of the budgeted amount are borne by the party that incurred such costs. Summit is also obligated to spend a specified minimum amount on the research and development of certain licensed products prior to the end of 2019. For the year ended December 31, 2018, the Company incurred approximately $8.6 million in collaboration expense for ezutromid, with no similar activity in 2017 and 2016. In June 2018, Summit announced that it is discontinuing the Phase 2 clinical trial on ezutromid. As a result, no development, regulatory or sales milestones were deemed as probable of being achieved as of December 31, 2018. For the years ended December 31, 2017, and 2016, the Company recorded a $22.0 million milestone payment and a $40.0 million up-front payment to Summit, respectively, as research and development expense in its consolidated statement of operations and comprehensive loss. University of Western Australia In April 2013, the Company and UWA entered into an agreement under which an existing exclusive license agreement between the Company and UWA was amended and restated (the “Amended and Restated UWA License Agreement”). The Amended and Restated UWA License Agreement grants the Company specific rights to the treatment of DMD by inducing the skipping of certain exons. EXONDYS 51 falls under the scope of the license agreement. Under the Amended and Restated UWA License Agreement, the Company may be required to make payments of up to $6.0 million in the aggregate to UWA based on the successful achievement of certain development and regulatory milestones relating to EXONDYS 51 and up to five additional product candidates. The Company may also be obligated to make payments to UWA of up to $20.0 million upon the achievement of certain sales milestones. Additionally, the Company may be required to pay a low-single-digit percentage royalty on net sales of products covered by issued patents licensed from UWA during the term of the Amended and Restated UWA License Agreement. However, the Company has the option to purchase future royalties up-front. Under this option, prior to the First Amendment (defined below), the Company could elect to make a one-time royalty payment of $30.0 million to UWA. In June 2016, the Company and UWA entered into the first amendment to the Amended and Restated UWA License Agreement (the “First Amendment”). Under the First Amendment, the Company was obligated to make an up-front payment of $7.0 million to UWA upon execution of the amendment. Under the terms of the First Amendment, UWA has waived certain rights and amended the timing of certain payments under the Amended and Restated UWA License Agreement, including lowering the up-front payment that is due by the Company upon exercise of the option to purchase future royalties up-front. Upon exercise of the option to purchase future royalties up-front, the Company will be obligated to make a $23.0 million payment to UWA. Additionally, the Company would still be obligated to make up to $20.0 million in payments to UWA upon achievement of certain sales milestones. For the year ended December 31, 2016, the Company recorded $7.6 million relating to the development milestone and up-front payments to UWA as research and development expense in the consolidated statement of operations and comprehensive loss as the Amended and Restated UWA License Agreement and its First Amendment were entered into before the FDA approval of EXONDYS 51. The Company did not incur any milestone expense for the years ended December 31, 2018 and 2017. Additionally, corresponding to the FDA approval and the subsequent commercial sale of EXONDYS 51, the Company recorded a $1.0 million milestone payment as an in-license right in its consolidated balance sheet in 2016. As of December 31, 2018, the in-license right is recorded net of $0.3 million accumulated amortization on the consolidated balance sheets. The amortization of the in-licensed right is recorded as cost of sales in the Company’s consolidated statements of operations and comprehensive loss. During the years ended December 31, 2018, 2017, and 2016, the Company did not incur royalty expense nor did it make any royalty payments to UWA but may be obligated to make these payments in the future.

LICENSE AND COLLABORATION AGREEMENTS

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

3. LICENSE AND COLLABORATION AGREEMENTS

Lysogene S.A.

On October 15, 2018, the Company entered into a license and collaboration agreement (the “Lysogene License and Collaboration Agreement”) for developing and commercializing LYS-SAF302, a gene therapy to treat Mucopolysaccharidosis type IIIA (“MPS IIIA”) with Lysogene S.A. (“Lysogene”). Under the terms of the Lysogene License and Collaboration Agreement, Lysogene will be responsible for completion of the pivotal trial, which commenced in the fourth quarter of 2018. The Company will have exclusive rights to commercialize LYS-SAF302 in the U.S. and all territories outside of Europe. Lysogene will retain exclusive commercial rights to LYS-SAF302 in Europe. The Company will be responsible for global manufacturing of LYS-SAF302 and will supply drug products to Lysogene for Europe. Lysogene also granted the Company certain option rights to an additional central nervous system targeted gene therapy candidate.

Concurrently with the execution of the Lysogene License and Collaboration Agreement, the Company entered into an equity investment agreement with Lysogene. Under the equity investment agreement, the Company purchased 950,606 shares of common stock issued by Lysogene, representing 8% of the outstanding equity of Lysogene at the time of the transaction.

The Company considered whether it would have to consolidate the operations of Lysogene and concluded that, while Lysogene is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Lysogene.

As a result of execution of the agreements, the Company made a payment of $28.0 million to Lysogene related to the up-front license fee, the option fee, the equity investment and reimbursement of certain development activities. Additionally, the Company may be liable for up to approximately $102.8 million in development, regulatory and sales milestones associated with the Lysogene License and Collaboration Agreement. Furthermore, the Company may be required to make tiered royalty payments based on net sales of the LYS-SAF302 product subsequent to its commercialization.

Of the $28.0 million payment to Lysogene, $1.9 million was allocated to the equity investment in Lysogene, based on the closing price of Lysogene’s common stock traded on the Euronext Paris Exchange on October 12, 2018, and was recorded as an other non-current asset. The remaining $26.1 million was allocated to the up-front license fee, the option fee, and reimbursement of certain development activities, and represents rights to potential future benefits associated with ongoing research and development activities that have no alternative future use. Accordingly, this amount was recorded as research and development expense as incurred. As of December 31, 2018, one development milestone was deemed as probable of being achieved. As a result, the Company recorded an accrued expense of $18.7 million which was classified as research and development expense.

Changes in the fair value of the equity investment in Lysogene are recorded to other income and expense in the Company’s consolidated statements of operations and other comprehensive loss. As of December 31, 2018, the Company recognized a loss of $0.2 million related to the change in fair market value of the equity investment.

Lacerta Therapeutics

On August 8, 2018 (the “Effective Date”), the Company entered into a License, Development and Option Agreement (the “Lacerta License Agreement”) with Lacerta Therapeutics, Inc. (“Lacerta”). Pursuant to the Lacerta License Agreement, the Company licensed exclusive worldwide rights to develop, manufacture and commercialize a pre-clinical Pompe product candidate (the “Pompe License”). Lacerta also granted the Company exclusive options to enter into exclusive license agreements to develop, manufacture and commercialize other gene therapy product candidates for Sanfilipo syndrome and L-Amino Acid Decarboxylase Deficiency for additional consideration of $42.0 million (collectively, the “Options”) when (and if) the Options are exercised. Additionally, the Company may be liable for up to approximately $44.0 million in development, regulatory and sales milestones associated with the Pompe License and may be required to make a high-single-digit royalty payments based on net sales of the Pompe product subsequent to its commercialization.

Concurrently with the execution of the Lacerta License Agreement, the Company entered into a Series A Preferred Stock Purchase Agreement (the “Purchase Agreement”) with Lacerta. Under the Purchase Agreement, the Company purchased approximately 4.5 million shares of Series A preferred stock issued by Lacerta.

The Company considered whether it would have to consolidate the operations of Lacerta and concluded that, while Lacerta is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Lacerta.

The Company made an up-front payment of $38.0 million to Lacerta in consideration of both the Lacerta License Agreement and the Purchase Agreement. This payment was allocated to the fair value of the Series A preferred stock investment, the Pompe License and the Options based on their respective relative fair values on the Effective Date. The fair value of the Options were determined using an option pricing model, whereas the Series A preferred stock investment was determined using a cost approach corroborated by the Black-Scholes option pricing model. The fair value of the Pompe License was determined by the income approach, using a discounted cash flow model based on projections of future cash flows that will arise from the Pompe product candidate. Accordingly: (i) $30.0 million was allocated to the Series A preferred stock investment, (ii) $8.0 million was allocated to the Pompe License, and (iii) no amount was allocated to the Options as they are far out of money and were determined to have a fair value of zero. The Series A preferred stock investment was initially measured at cost and classified as an other non-current asset in the accompanying consolidated balance sheets. Subsequently, changes in the carrying value of the investment will be reported as a component of earnings whenever there are observable price changes in orderly transactions for identical or similar investments of Lacerta in the future. The amount allocated to the Pompe License represents rights to potential future benefits associated with ongoing research and development activities that have no alternative future use. Accordingly, this amount has been recorded as research and development expense in the accompanying consolidated statements of operations and comprehensive loss for the year ended December 31, 2018. As of December 31, 2018, no development milestones were deemed as probable of being achieved and, accordingly, no research and development expense was recognized related to these development milestones.

Myonexus Therapeutics

On May 3, 2018, the Company entered into a Warrant to Purchase Common Stock Agreement (“Warrant Agreement”) with Myonexus Therapeutics, Inc. (“Myonexus”). Pursuant to the terms of the Warrant Agreement, the Company made an up-front payment of $60.0 million to purchase an exclusive option to acquire Myonexus for $200.0 million plus sales-related and regulatory-related contingent payments. Prior to the exercise of the option to acquire Myonexus, the Company may be required to make additional development milestone payments to Myonexus of up to $45.0 million over an approximately two-year evaluation period.

The Company considered whether it would have to consolidate the operations of Myonexus and concluded that, while Myonexus is a variable interest entity, the Company is not the primary beneficiary as it does not have the power to direct the activities that would most significantly impact the economic performance of Myonexus.

As of December 31, 2018, the Company made an up-front payment of $60.0 million and milestone payments totaling $20.0 million to Myonexus corresponding to execution of the Warrant Agreement and achievement of two development milestones, respectively. Additionally, the third development milestone for $5.0 million was deemed probable of being achieved as of December 31, 2018, and has been recorded as an accrued expense. Prior to regulatory approval, all consideration paid to Myonexus represents rights to potential future benefits associated with Myonexus’s ongoing research and development activities, which have not reached technological feasibility and have no alternative future use. Accordingly, the Company recorded $85.0 million for the year ended December 31, 2018 as research and development expense in the accompanying consolidated statements of operations and comprehensive loss.

Nationwide Children’s Hospital

On December 29, 2016, the Company entered into an exclusive option agreement with Nationwide Children’s Hospital (“Nationwide”) from which the Company obtained an exclusive right to acquire a worldwide license of the micro-dystrophin gene therapy technology for DMD and Becker muscular dystrophy. On October 8, 2018, the Company exercised the option and entered into a license agreement with Nationwide (“Nationwide License Agreement”). Pursuant to the Nationwide License Agreement, the Company licensed exclusive worldwide rights to develop, manufacture and commercialize micro-dystrophin gene therapy product candidates. Under the agreement, the Company made an up-front payment of $1.0 million to Nationwide, which was recorded as research and development expense in the accompanying consolidated statements of operations and comprehensive loss for the year ended December 31, 2018. Additionally, the Company may be required to make up to $29.0 million in development, regulatory and sale milestone payments per micro-dystrophin product and a low-single-digit royalty payments based on net sales of the micro-dystrophin products upon commercialization. As of December 31, 2018, no development milestones were deemed as probable of being achieved and, accordingly, no research and development expense was recognized related to these development milestones.

BioMarin Pharmaceutical, Inc.

In July 2017, the Company and UWA entered into a settlement agreement with BioMarin Leiden Holding BV, its subsidiaries BioMarin Nederlands BV and BioMarin Technologies BV (collectively, “BioMarin”). On the same day, the Company entered into a license agreement with BioMarin and Academisch Ziekenhuis Leiden (“AZL”) (collectively with the Company, UWA and BioMarin, the “Settlement Parties”). Under these agreements, BioMarin agreed to provide the Company with an exclusive license to certain intellectual property with an option to convert the exclusive license into a co-exclusive license and the Settlement Parties agreed to stop most existing efforts to continue with ongoing litigation and opposition and other administrative proceedings concerning BioMarin’s intellectual property. Under terms of the agreements, the Company agreed to make total up-front payments of $35.0 million upon execution of the agreements, consisting of $20.0 million under the settlement agreement and $15.0 million under the license agreement. Additionally, the Company may be liable for up to approximately $65.0 million in regulatory and sales milestones for eteplirsen as well as exon 45 and exon 53 skipping product candidates. BioMarin will also be eligible to receive royalty payments, ranging from 4% - 8%, for exon 51 skipping products, exon 45 skipping products and exon 53 skipping products. The royalty terms under the license agreement will expire in December 2023 in the U.S. and September 2024 in the EU.

In connection with the above agreements, in July 2017, the Company made a cash payment of $35.0 million to BioMarin. Of this amount, $6.6 million was recorded as an intangible asset on the Company’s consolidated balance sheets. The remaining amount of $28.4 million was expensed as incurred as EXONDYS 51 settlement and license charges in the Company’s consolidated statements of operations and comprehensive loss.

The $6.6 million intangible asset represents the fair value of the U.S. license to BioMarin’s intellectual property related to EXONDYS 51, which was determined by an income-based approach, and is being amortized on a straight-line basis over the remaining life of the patent. For the year ended December 31, 2018, the Company recognized intangible asset amortization expense and royalty expense of approximately $0.9 million and $15.1 million, respectively. For the year ended December 31, 2017, the Company recognized intangible asset amortization expense and royalty expense of approximately $1.0 million and $4.7 million, respectively. The royalties are included in cost of sales in the Company’s consolidated statements of operations and comprehensive loss. As of December 31, 2018, no regulatory or sales milestones were deemed as probable of being achieved and, accordingly, no additional in-licensed rights were recognized related to these milestones.

Summit (Oxford) Ltd.

In October 2016, the Company entered into an exclusive Collaboration and License Agreement (the “Summit Collaboration Agreement”) with Summit which grants the Company the exclusive right to commercialize products in Summit’s utrophin modulator pipeline in the EU, Switzerland, Norway, Iceland, Turkey and the Commonwealth of Independent States (the “Licensed Territory”).

Under the terms of the Summit Collaboration Agreement, the Company made an up-front payment of $40.0 million to Summit, with additional payments of up to $192.0 million based on achievement of certain development and regulatory milestones for ezutromid, a Summit product candidate in its utrophin modulator pipeline. For each of Summit’s future generation small molecule utrophin modulators, the Company may be required to make up to $290.0 million in development and regulatory milestone payments. Additionally, on a product-by-product basis, the Company may be required to make up to $330.0 million in sales milestone payments. The Summit Collaboration Agreement also grants the Company an option to expand the Licensed Territory (“Option Territory”). If the Company exercises this option, it will be liable for a one-time $10.0 million option fee as well as up to $7.0 million in regulatory milestone payments. For each licensed product in the Option Territory, the Company may be liable for up to $82.5 million in sales milestone payments. Additionally, the Company may be required to make tiered royalty payments ranging from a low to high teens percentage of net sales on a product-by-product basis in the Licensed Territory.

Under the Summit Collaboration Agreement, a joint steering committee was established to plan, monitor and coordinate future development activities for ezutromid and future generation small molecule utrophin modulators. Summit was solely responsible for all research and development costs for the licensed products until December 31, 2017. Thereafter, Summit will be responsible for 55.0% of the budgeted research and development costs related to the licensed products in the Licensed Territory, and the Company will be responsible for 45.0% of such costs. Any costs in excess of 110.0% of the budgeted amount are borne by the party that incurred such costs. Summit is also obligated to spend a specified minimum amount on the research and development of certain licensed products prior to the end of 2019. For the year ended December 31, 2018, the Company incurred approximately $8.6 million in collaboration expense for ezutromid, with no similar activity in 2017 and 2016.

In June 2018, Summit announced that it is discontinuing the Phase 2 clinical trial on ezutromid. As a result, no development, regulatory or sales milestones were deemed as probable of being achieved as of December 31, 2018. For the years ended December 31, 2017, and 2016, the Company recorded a $22.0 million milestone payment and a $40.0 million up-front payment to Summit, respectively, as research and development expense in its consolidated statement of operations and comprehensive loss.

University of Western Australia

In April 2013, the Company and UWA entered into an agreement under which an existing exclusive license agreement between the Company and UWA was amended and restated (the “Amended and Restated UWA License Agreement”). The Amended and Restated UWA License Agreement grants the Company specific rights to the treatment of DMD by inducing the skipping of certain exons. EXONDYS 51 falls under the scope of the license agreement. Under the Amended and Restated UWA License Agreement, the Company may be required to make payments of up to $6.0 million in the aggregate to UWA based on the successful achievement of certain development and regulatory milestones relating to EXONDYS 51 and up to five additional product candidates. The Company may also be obligated to make payments to UWA of up to $20.0 million upon the achievement of certain sales milestones. Additionally, the Company may be required to pay a low-single-digit percentage royalty on net sales of products covered by issued patents licensed from UWA during the term of the Amended and Restated UWA License Agreement. However, the Company has the option to purchase future royalties up-front. Under this option, prior to the First Amendment (defined below), the Company could elect to make a one-time royalty payment of $30.0 million to UWA.

In June 2016, the Company and UWA entered into the first amendment to the Amended and Restated UWA License Agreement (the “First Amendment”). Under the First Amendment, the Company was obligated to make an up-front payment of $7.0 million to UWA upon execution of the amendment. Under the terms of the First Amendment, UWA has waived certain rights and amended the timing of certain payments under the Amended and Restated UWA License Agreement, including lowering the up-front payment that is due by the Company upon exercise of the option to purchase future royalties up-front. Upon exercise of the option to purchase future royalties up-front, the Company will be obligated to make a $23.0 million payment to UWA. Additionally, the Company would still be obligated to make up to $20.0 million in payments to UWA upon achievement of certain sales milestones.

For the year ended December 31, 2016, the Company recorded $7.6 million relating to the development milestone and up-front payments to UWA as research and development expense in the consolidated statement of operations and comprehensive loss as the Amended and Restated UWA License Agreement and its First Amendment were entered into before the FDA approval of EXONDYS 51. The Company did not incur any milestone expense for the years ended December 31, 2018 and 2017. Additionally, corresponding to the FDA approval and the subsequent commercial sale of EXONDYS 51, the Company recorded a $1.0 million milestone payment as an in-license right in its consolidated balance sheet in 2016. As of December 31, 2018, the in-license right is recorded net of $0.3 million accumulated amortization on the consolidated balance sheets. The amortization of the in-licensed right is recorded as cost of sales in the Company’s consolidated statements of operations and comprehensive loss. During the years ended December 31, 2018, 2017, and 2016, the Company did not incur royalty expense nor did it make any royalty payments to UWA but may be obligated to make these payments in the future.