COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS	9 Months Ended
Sep. 30, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS	3. COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS Lacerta Therapeutics On August 8, 2018 (the “Effective Date”), the Company entered into a License, Development and Option Agreement (the “License Agreement”) with Lacerta Therapeutics, Inc. (“Lacerta”). Pursuant to the License Agreement, the Company licensed in 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 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 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 using a discounted cash flow model under the income approach. 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. fThe Series A preferred stock investment was initially measured at cost and classified as an other non-current asset in the accompanying unaudited condensed 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 unaudited condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2018. Myonexus Therapeutics In May 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 September 30, 2018, the Company made an up-front payment of $60.0 million and a milestone payment of $10.0 million to Myonexus corresponding to execution of the Warrant Agreement in May 2018 and achievement of a development milestone in September 2018, respectively. Prior to regulatory approval, considerations paid to Myonexus represent 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 $10.0 million and $70.0 million for the three and nine months ended September 30, 2018, respectively, as research and development expense in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss. Brammer Bio MA, LLC In June 2018, the Company entered into a Development, Commercial Manufacturing and Supply Agreement (“Brammer Manufacturing Agreement”), with Brammer Bio MA, LLC (“Brammer”). Pursuant to the terms of the Brammer Manufacturing Agreement, Brammer agreed to provide the Company with access to clinical and commercial manufacturing capacity for its gene therapy programs. As part of the Brammer Manufacturing Agreement, the Company will purchase product in batches from Brammer, subject to minimum and maximum annual purchase requirements. Further, the Company: (i) was required to make a $20.0 million advance payment to Brammer upon execution of the agreement, (ii) is required to make two non-refundable payments of $5.0 million each to Brammer in the third and fourth quarter of 2018 to be used in the specification, selection, and procurement of the related process equipment to be utilized under the agreement, and (iii) is required to make a $10.0 million quarterly capacity access fee payment to Brammer throughout the term of the agreement. However, through June 30, 2019, a reduced quarterly capacity access fee will be in effect as Brammer works towards achieving full capacity at its facility. In addition, one-tenth of the $20.0 million advance payment will be applied as a credit to the quarterly capacity access fees due and payable from July 1, 2019 through December 31, 2021, resulting in a net capacity access fee of $8.0 million. The term of the Brammer Manufacturing Agreement will continue for a period of six years following the first regulatory approval of a product manufactured under the agreement. The term will automatically renew for successive two years unless the Company notifies Brammer of its intention not to renew (no less than twenty-four months prior to the expiration of the term). The Company also has the ability to terminate the agreement prior to expiration but would be required to continue remitting capacity access fees to Brammer for up to eight additional quarters. The Company has determined that the Brammer Manufacturing Agreement does not contain an embedded lease because it does not convey the right to control the use of the facility or related equipment. This conclusion was based on the Company’s inability or right to control physical access to Brammer’s facility and the related equipment, and the ability of one or more parties, other than the Company, to take more than a minor amount of the output that will be produced during the term of the agreement. As of September 30, 2018, the Company has made payments totaling $35.0 million to Brammer under the Brammer Manufacturing Agreement consisting of: (i) the $20.0 million advance payment made in June 2018, (ii) the first $5.0 million process equipment fee paid in July 2018, and (iii) the first two reduced quarterly capacity access fee payments of $5.0 million made in July 2018 and September 2018. Of the cumulative amount paid of $35.0 million, $2.2 million was recorded as an other current asset and $32.8 million as an other non-current asset, in the accompanying unaudited condensed consolidated balance sheets. The advance payment and process equipment fee will be amortized over their expected economic benefit to research and development expense, prior to regulatory approval of the related product, commencing upon the first batch delivery to the Company, which is currently estimated to occur in July 2019. Upon regulatory approval, amortization expense will be classified to cost of sales. Capacity access fee payments made prior to the first batch delivery to the Company will be capitalized and amortized to expense in a manner similar to the advance payment and process equipment fee. Capacity access fee payments made subsequent to the first batch delivery to the Company will be expensed as incurred to research and development expense, prior to regulatory approval of the related product. Upon regulatory approval, the expense associated with capacity access fee payments will be classified to cost of sales. In the event the Company does not expect services under the Brammer Manufacturing Agreement to be rendered, the capitalized payments will be charged to expense.

3. COLLABORATION, LICENSE AND MANUFACTURING AGREEMENTS

Lacerta Therapeutics

On August 8, 2018 (the “Effective Date”), the Company entered into a License, Development and Option Agreement (the “License Agreement”) with Lacerta Therapeutics, Inc. (“Lacerta”). Pursuant to the License Agreement, the Company licensed in 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 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 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 using a discounted cash flow model under the income approach. 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. fThe Series A preferred stock investment was initially measured at cost and classified as an other non-current asset in the accompanying unaudited condensed 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 unaudited condensed consolidated statements of operations and comprehensive loss for the three and nine months ended September 30, 2018.

Myonexus Therapeutics

In May 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 September 30, 2018, the Company made an up-front payment of $60.0 million and a milestone payment of $10.0 million to Myonexus corresponding to execution of the Warrant Agreement in May 2018 and achievement of a development milestone in September 2018, respectively. Prior to regulatory approval, considerations paid to Myonexus represent 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 $10.0 million and $70.0 million for the three and nine months ended September 30, 2018, respectively, as research and development expense in the accompanying unaudited condensed consolidated statements of operations and comprehensive loss.

Brammer Bio MA, LLC

In June 2018, the Company entered into a Development, Commercial Manufacturing and Supply Agreement (“Brammer Manufacturing Agreement”), with Brammer Bio MA, LLC (“Brammer”). Pursuant to the terms of the Brammer Manufacturing Agreement, Brammer agreed to provide the Company with access to clinical and commercial manufacturing capacity for its gene therapy programs.

As part of the Brammer Manufacturing Agreement, the Company will purchase product in batches from Brammer, subject to minimum and maximum annual purchase requirements. Further, the Company: (i) was required to make a $20.0 million advance payment to Brammer upon execution of the agreement, (ii) is required to make two non-refundable payments of $5.0 million each to Brammer in the third and fourth quarter of 2018 to be used in the specification, selection, and procurement of the related process equipment to be utilized under the agreement, and (iii) is required to make a $10.0 million quarterly capacity access fee payment to Brammer throughout the term of the agreement. However, through June 30, 2019, a reduced quarterly capacity access fee will be in effect as Brammer works towards achieving full capacity at its facility. In addition, one-tenth of the $20.0 million advance payment will be applied as a credit to the quarterly capacity access fees due and payable from July 1, 2019 through December 31, 2021, resulting in a net capacity access fee of $8.0 million.

The term of the Brammer Manufacturing Agreement will continue for a period of six years following the first regulatory approval of a product manufactured under the agreement. The term will automatically renew for successive two years unless the Company notifies Brammer of its intention not to renew (no less than twenty-four months prior to the expiration of the term). The Company also has the ability to terminate the agreement prior to expiration but would be required to continue remitting capacity access fees to Brammer for up to eight additional quarters.

The Company has determined that the Brammer Manufacturing Agreement does not contain an embedded lease because it does not convey the right to control the use of the facility or related equipment. This conclusion was based on the Company’s inability or right to control physical access to Brammer’s facility and the related equipment, and the ability of one or more parties, other than the Company, to take more than a minor amount of the output that will be produced during the term of the agreement.

As of September 30, 2018, the Company has made payments totaling $35.0 million to Brammer under the Brammer Manufacturing Agreement consisting of: (i) the $20.0 million advance payment made in June 2018, (ii) the first $5.0 million process equipment fee paid in July 2018, and (iii) the first two reduced quarterly capacity access fee payments of $5.0 million made in July 2018 and September 2018. Of the cumulative amount paid of $35.0 million, $2.2 million was recorded as an other current asset and $32.8 million as an other non-current asset, in the accompanying unaudited condensed consolidated balance sheets.

The advance payment and process equipment fee will be amortized over their expected economic benefit to research and development expense, prior to regulatory approval of the related product, commencing upon the first batch delivery to the Company, which is currently estimated to occur in July 2019. Upon regulatory approval, amortization expense will be classified to cost of sales. Capacity access fee payments made prior to the first batch delivery to the Company will be capitalized and amortized to expense in a manner similar to the advance payment and process equipment fee. Capacity access fee payments made subsequent to the first batch delivery to the Company will be expensed as incurred to research and development expense, prior to regulatory approval of the related product. Upon regulatory approval, the expense associated with capacity access fee payments will be classified to cost of sales. In the event the Company does not expect services under the Brammer Manufacturing Agreement to be rendered, the capitalized payments will be charged to expense.