Collaboration and License Agreement	12 Months Ended
Dec. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
COLLABORATION AND LICENSE AGREEMENT	16. COLLABORATION AND LICENSE AGREEMENT In November 2017, the Company entered into a collaboration and license agreement (the “Collaboration Agreement”) with Novartis Institutes of BioMedical Research, Inc. (“Novartis”) for the research, development, manufacturing and commercialization of products using the Company’s gene-editing technology for the treatment of certain ophthalmic targets and sickle cell disease. In February 2019, Novartis elected to discontinue the sickle cell disease program under the Collaboration Agreement effective in August 2019. The Company continues to work with Novartis to identify new targets for the partnership based on the existing exploratory research component of the agreement, and the collaboration on two ophthalmic programs also continues. The Company has assumed all worldwide rights to the sickle cell disease program, and its efforts to develop an in vivo gene editing approach are ongoing. Under the terms of the Collaboration Agreement, taking into account Novartis’ election to discontinue the sickle cell disease program, the Company granted Novartis a research license, a development and commercialization license, and a manufacturing license, under certain of its intellectual property rights to research, develop, manufacture and commercialize the ophthalmic targets. Upon entering into the Collaboration Agreement, the Company received an upfront, nonrefundable payment of $35.0 million and issued additional shares of its Series B preferred stock to Novartis for consideration of $10.0 million. The Collaboration Agreement consists of a research term, where the Company and Novartis are collaborating to perform research and conduct preclinical development to identify candidates that modulate the ophthalmic targets. The Collaboration Agreement also includes exploratory work on the applicability of the gene-editing technology with respect to other gene targets. The Company’s obligation to perform such exploratory research concludes in November 2020. Novartis may select up to four targets, with limited substitution rights. The Company is responsible for the manufacturing of proprietary research grade human hematopoietic stem cell derived adeno-associated virus vectors (“AAVHSCs”) during the research term. Research activities performed by the Company are being reimbursed at a full-time equivalent rate (“FTE”) and manufacturing activities will be reimbursed at cost, as specified and defined in the Collaboration Agreement. Novartis is required to pay the Company a target fee of $5.0 million for each target that meets certain success criteria during the research term (the “target fee trigger date”), up to a maximum of four targets. The research term will continue for five years from the effective date of the Collaboration Agreement. Pursuant to the Collaboration Agreement, the Company will also participate on a joint steering committee and a joint manufacturing subcommittee, with equal representation from both the Company and Novartis. Novartis has the exclusive right to develop and commercialize up to four candidates or products arising from the research activities. Subject to certain limitations pursuant to the terms of the Collaboration Agreement, Novartis will fund all development and commercialization costs. The Company will be responsible for manufacturing candidates and products for Novartis during the development and commercialization terms. The Company’s manufacturing activities will be reimbursed at cost during the development term and at cost plus a margin during the commercialization term, as defined in the Collaboration Agreement. If the Company is not able to manufacture candidates or products that meet the quality or quantity requirements of Novartis, then Novartis shall have the right to designate a third-party contract manufacturer or manufacture such candidates or products itself. In accordance with the Collaboration Agreement, taking into consideration Novartis’ election to discontinue the sickle cell disease program, the Company is also eligible to receive up to a total of $530.0 million in milestone payments, including up to $180.0 million in development milestone payments, up to $170.0 million in regulatory milestone payments and up to $180.0 million in commercial milestone payments, with respect to the licensed products. The Company is also eligible to earn tiered royalties on net sales of licensed products by Novartis, its affiliates or sublicensees, ranging from mid single-digit, to sub-teen double-digit percentages, and such royalties are potentially subject to various reductions and offsets. If any of the exploratory research efforts are advanced into formal research and development programs, the parties will negotiate the economics including potential milestone payments for such programs. Unless earlier terminated, the Collaboration Agreement will continue on a target-by-target basis until the expiration of all applicable royalty terms with respect to all products that modulate such target on a country-by-country-basis. Either party may terminate the agreement on a target-by-target basis for the other party’s material breach with respect to such target, or in the event of the other party’s bankruptcy. Novartis may terminate the agreement for convenience on a target-by-target basis. The Company may terminate the agreement if Novartis files, or joins a third party in filing or maintaining, a patent challenge against certain of the patent rights licensed to Novartis under the terms of the agreement. There are no performance, cancellation, termination or refund provisions in the arrangement that contain material financial consequences to the Company. Revenue Recognition The Company has identified the following deliverables in the Collaboration Agreement in accordance with the provisions of ASC Topic 605-25, Revenue Recognition—Multiple Element Arrangements: (1) the research license, (2) the development and commercialization license, (3) the manufacturing license, (4) research activities performed by the Company, (5) service on the joint committees, (6) manufacturing during the research and development terms, and (7) manufacturing during the commercialization term. Except for manufacturing during the commercialization term, none of the other deliverables have standalone value to the customer. Since separability criteria have not been met for these deliverables, the deliverables are being accounted for as a single combined unit of accounting at the outset of the Collaboration Agreement (the “combined unit of accounting”). The manufacturing services during the commercialization term will be accounted for as a separate unit of accounting. Upon entering into the Collaboration Agreement, the Company received a nonrefundable upfront payment of $35.0 million and a $10.0 million investment in its Series B preferred stock by Novartis. The Company recorded the Series B preferred stock at its estimated fair value of $11.7 million, including $1.7 million of the upfront payment, and allocated the remaining $33.3 million of the upfront payment to the Collaboration Agreement. The Company believes the consideration it will receive for the manufacturing services during the commercialization term, when and if it provides such services, is representative of the best estimate of selling price of the services. Therefore, the entire $33.3 million of upfront nonrefundable consideration was allocated to the combined unit of accounting. At the inception of the Collaboration Agreement, the Company could not objectively measure the level of effort required to fulfill its obligations for the combined unit of accounting. Therefore, revenue is being recognized on a straight-line basis over the estimated period of performance for the combined unit of accounting, which the Company estimates to be approximately ten years from the inception of the Collaboration Agreement. The Company commenced revenue recognition upon delivery of the final deliverable included in the combined unit of accounting which occurred in January 2018. Accordingly, no amounts of revenue were recognized for the year ended December 31, 2017. All payments due or received from Novartis as of December 31, 2017, including amounts due for research activities performed, were recorded as deferred revenue as of December 31, 2017. The Company recognized revenue of $3.7 million for the year ended December 31, 2018, based on a straight-line basis over the estimated period of performance taking into consideration all upfront payments and research funding payments together as a single unit. The Company had a $0.8 million receivable from Novartis as of December 31, 2018, which was included in prepaid expenses and other current assets on the Company’s consolidated balance sheet. The amount recorded as deferred revenue under this agreement totaled $33.2 million as of December 31, 2018.

Collaboration and License Agreement

12 Months Ended

Dec. 31, 2018

Organization Consolidation And Presentation Of Financial Statements [Abstract]

16. COLLABORATION AND LICENSE AGREEMENT

In November 2017, the Company entered into a collaboration and license agreement (the “Collaboration Agreement”) with Novartis Institutes of BioMedical Research, Inc. (“Novartis”) for the research, development, manufacturing and commercialization of products using the Company’s gene-editing technology for the treatment of certain ophthalmic targets and sickle cell disease. In February 2019, Novartis elected to discontinue the sickle cell disease program under the Collaboration Agreement effective in August 2019. The Company continues to work with Novartis to identify new targets for the partnership based on the existing exploratory research component of the agreement, and the collaboration on two ophthalmic programs also continues. The Company has assumed all worldwide rights to the sickle cell disease program, and its efforts to develop an in vivo gene editing approach are ongoing.

Under the terms of the Collaboration Agreement, taking into account Novartis’ election to discontinue the sickle cell disease program, the Company granted Novartis a research license, a development and commercialization license, and a manufacturing license, under certain of its intellectual property rights to research, develop, manufacture and commercialize the ophthalmic targets. Upon entering into the Collaboration Agreement, the Company received an upfront, nonrefundable payment of $35.0 million and issued additional shares of its Series B preferred stock to Novartis for consideration of $10.0 million.

The Collaboration Agreement consists of a research term, where the Company and Novartis are collaborating to perform research and conduct preclinical development to identify candidates that modulate the ophthalmic targets. The Collaboration Agreement also includes exploratory work on the applicability of the gene-editing technology with respect to other gene targets. The Company’s obligation to perform such exploratory research concludes in November 2020. Novartis may select up to four targets, with limited substitution rights. The Company is responsible for the manufacturing of proprietary research grade human hematopoietic stem cell derived adeno-associated virus vectors (“AAVHSCs”) during the research term. Research activities performed by the Company are being reimbursed at a full-time equivalent rate (“FTE”) and manufacturing activities will be reimbursed at cost, as specified and defined in the Collaboration Agreement. Novartis is required to pay the Company a target fee of $5.0 million for each target that meets certain success criteria during the research term (the “target fee trigger date”), up to a maximum of four targets. The research term will continue for five years from the effective date of the Collaboration Agreement. Pursuant to the Collaboration Agreement, the Company will also participate on a joint steering committee and a joint manufacturing subcommittee, with equal representation from both the Company and Novartis.

Novartis has the exclusive right to develop and commercialize up to four candidates or products arising from the research activities. Subject to certain limitations pursuant to the terms of the Collaboration Agreement, Novartis will fund all development and commercialization costs. The Company will be responsible for manufacturing candidates and products for Novartis during the development and commercialization terms. The Company’s manufacturing activities will be reimbursed at cost during the development term and at cost plus a margin during the commercialization term, as defined in the Collaboration Agreement. If the Company is not able to manufacture candidates or products that meet the quality or quantity requirements of Novartis, then Novartis shall have the right to designate a third-party contract manufacturer or manufacture such candidates or products itself.

In accordance with the Collaboration Agreement, taking into consideration Novartis’ election to discontinue the sickle cell disease program, the Company is also eligible to receive up to a total of $530.0 million in milestone payments, including up to $180.0 million in development milestone payments, up to $170.0 million in regulatory milestone payments and up to $180.0 million in commercial milestone payments, with respect to the licensed products. The Company is also eligible to earn tiered royalties on net sales of licensed products by Novartis, its affiliates or sublicensees, ranging from mid single-digit, to sub-teen double-digit percentages, and such royalties are potentially subject to various reductions and offsets. If any of the exploratory research efforts are advanced into formal research and development programs, the parties will negotiate the economics including potential milestone payments for such programs.

Unless earlier terminated, the Collaboration Agreement will continue on a target-by-target basis until the expiration of all applicable royalty terms with respect to all products that modulate such target on a country-by-country-basis. Either party may terminate the agreement on a target-by-target basis for the other party’s material breach with respect to such target, or in the event of the other party’s bankruptcy. Novartis may terminate the agreement for convenience on a target-by-target basis. The Company may terminate the agreement if Novartis files, or joins a third party in filing or maintaining, a patent challenge against certain of the patent rights licensed to Novartis under the terms of the agreement. There are no performance, cancellation, termination or refund provisions in the arrangement that contain material financial consequences to the Company.

Revenue Recognition

The Company has identified the following deliverables in the Collaboration Agreement in accordance with the provisions of ASC Topic 605-25, Revenue Recognition—Multiple Element Arrangements: (1) the research license, (2) the development and commercialization license, (3) the manufacturing license, (4) research activities performed by the Company, (5) service on the joint committees, (6) manufacturing during the research and development terms, and (7) manufacturing during the commercialization term. Except for manufacturing during the commercialization term, none of the other deliverables have standalone value to the customer. Since separability criteria have not been met for these deliverables, the deliverables are being accounted for as a single combined unit of accounting at the outset of the Collaboration Agreement (the “combined unit of accounting”). The manufacturing services during the commercialization term will be accounted for as a separate unit of accounting.

Upon entering into the Collaboration Agreement, the Company received a nonrefundable upfront payment of $35.0 million and a $10.0 million investment in its Series B preferred stock by Novartis. The Company recorded the Series B preferred stock at its estimated fair value of $11.7 million, including $1.7 million of the upfront payment, and allocated the remaining $33.3 million of the upfront payment to the Collaboration Agreement. The Company believes the consideration it will receive for the manufacturing services during the commercialization term, when and if it provides such services, is representative of the best estimate of selling price of the services. Therefore, the entire $33.3 million of upfront nonrefundable consideration was allocated to the combined unit of accounting.

At the inception of the Collaboration Agreement, the Company could not objectively measure the level of effort required to fulfill its obligations for the combined unit of accounting. Therefore, revenue is being recognized on a straight-line basis over the estimated period of performance for the combined unit of accounting, which the Company estimates to be approximately ten years from the inception of the Collaboration Agreement. The Company commenced revenue recognition upon delivery of the final deliverable included in the combined unit of accounting which occurred in January 2018. Accordingly, no amounts of revenue were recognized for the year ended December 31, 2017. All payments due or received from Novartis as of December 31, 2017, including amounts due for research activities performed, were recorded as deferred revenue as of December 31, 2017.

The Company recognized revenue of $3.7 million for the year ended December 31, 2018, based on a straight-line basis over the estimated period of performance taking into consideration all upfront payments and research funding payments together as a single unit. The Company had a $0.8 million receivable from Novartis as of December 31, 2018, which was included in prepaid expenses and other current assets on the Company’s consolidated balance sheet. The amount recorded as deferred revenue under this agreement totaled $33.2 million as of December 31, 2018.