Intellia Therapeutics (NTLA) 10-Q 1 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 27, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Trading Symbol	NTLA
Entity Registrant Name	INTELLIA THERAPEUTICS, INC.
Entity Central Index Key	1,652,130
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		43,089,810

Consolidated Balance Sheets (Un

Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current Assets:
Cash and cash equivalents	$ 327,778	$ 340,678
Accounts receivable	7,466	10,471
Prepaid expenses and other current assets	2,476	3,681
Total current assets	337,720	354,830
Property and equipment, net	16,010	15,272
Other assets	5,815	6,133
Total Assets	359,545	376,235
Current Liabilities:
Accounts payable	1,916	2,172
Accrued expenses	6,605	7,999
Current portion of deferred revenue	17,062	21,188
Total current liabilities	25,583	31,359
Deferred revenue, net of current portion	38,332	44,111
Other long-term liabilities	131	168
Commitments and contingencies
Stockholders' Equity:
Common stock, $0.0001 par value; 120,000,000 shares authorized, 43,091,922 shares and 42,384,623 shares issued and outstanding, respectively	4	4
Additional paid-in capital	432,533	421,706
Accumulated deficit	(137,038)	(121,113)
Total stockholders' equity	295,499	300,597
Total Liabilities and Stockholders' Equity	$ 359,545	$ 376,235

Consolidated Balance Sheets (U3

Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	43,091,922	42,384,623
Common stock, shares outstanding	43,091,922	42,384,623

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Income Statement [Abstract]
Collaboration revenue	$ 7,469	$ 6,215
Operating expenses:
Research and development	22,493	13,431
General and administrative	7,406	5,732
Total operating expenses	29,899	19,163
Operating loss	(22,430)	(12,948)
Interest income	1,074	317
Net loss	$ (21,356)	$ (12,631)
Net loss per share attributable to common stockholders, basic and diluted	$ (0.51)	$ (0.36)
Weighted average shares outstanding, basic and diluted	42,043	34,723

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (21,356)	$ (12,631)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	1,012	660
Equity-based compensation	4,107	2,630
Changes in operating assets and liabilities:
Accounts receivable	3,005	4,011
Prepaid expenses and other current assets	1,205	704
Accounts payable	59	(954)
Accrued expenses	(1,609)	(1,893)
Deferred revenue	(4,474)	(4,278)
Other assets	318	268
Other long-term liabilities	(37)	85
Net cash used in operating activities	(17,770)	(11,398)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(1,850)	(4,162)
Net cash used in investing activities	(1,850)	(4,162)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from options exercised	6,720	47
Net cash provided by financing activities	6,720	47
Net decrease in cash and cash equivalents	(12,900)	(15,513)
Cash and cash equivalents, beginning of period	340,678	273,064
Cash and cash equivalents, end of period	327,778	257,551
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	$ 703	$ 378

Overview and Basis of Presentat

Overview and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Overview and Basis of Presentation	1. Overview and Basis of Presentation Intellia Therapeutics, Inc. (collectively referred to with its wholly owned, controlled subsidiary, Intellia Securities Corp., as “Intellia” or the “Company”) is a genome editing company focused on developing curative therapeutics utilizing a biological tool known as CRISPR/Cas9 The consolidated financial statements of the Company included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these consolidated financial statements should be read in conjunction with the financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2017. The unaudited consolidated financial statements include the accounts of Intellia Therapeutics, Inc. and its wholly-owned, controlled subsidiary, Intellia Securities Corp. All intercompany balances and transactions have been eliminated in consolidation. The only item comprising comprehensive loss is net loss. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The three months ended March 31, 2018 and 2017 are referred to as the first quarter of 2018 and 2017, respectively. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Revenue Recognition In May 2014, the Financing Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606) In accordance with ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these goods and services. To achieve this core principle, the Company applies the following five steps: 1) Identify the contract with the customer A contract with a customer exists when (i) the Company enters into an enforceable contract with a customer that defines each party’s rights regarding the goods or services to be transferred and identifies the related payment terms, (ii) the contract has commercial substance, and (iii) the Company determines that collection of substantially all consideration for goods and services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s intent and ability to pay, which is based on a variety of factors including the customer’s historical payment experience, or in the case of a new customer, published credit and financial information pertaining to the customer. 2) Identify the performance obligations in the contract Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the good or service either on its own or together with other available resources, and are distinct in the context of the contract, whereby the transfer of the good or service is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised goods and services, the Company must apply judgment to determine whether promised goods and services are both capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. 3) The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. Determining the transaction price requires significant judgment, which is discussed in further detail for each of the Company’s collaboration agreements in Note 5. In addition, neither of the Company’s contracts as of March 31, 2018 contained a significant financing component. 4) Allocate the transaction price to performance obligations in the contract If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. However, if a series of distinct services that are substantially the same qualifies as a single performance obligation in a contract with variable consideration, the Company must determine if the variable consideration is attributable to the entire contract or to a specific part of the contract. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices. The Company typically determines standalone selling prices using an adjusted market assessment approach model. 5) Recognize revenue when or as the Company satisfies a performance obligation The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (ii) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced, or (iii) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer. Examples of control are using the asset to produce goods or services, enhance the value of other assets, or settle liabilities, and holding or selling the asset. As of March 31, 2018, the Company’s only revenue recognized is related to collaboration agreements with third parties. As discussed in further detail in Note 5, the Company enters into out-licensing agreements which are within the scope of ASC 606, under which it licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront fees; development, regulatory, and commercial milestone payments; research and development funding payments; and royalties on the net sales of licensed products. Each of these payments results in collaboration revenues, except for revenues from royalties on the net sales of licensed products, which are classified as royalty revenues. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from consideration allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the licenses. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments: At the inception of each arrangement that includes development milestone payments, the Company evaluates the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received and therefore revenue recognized is constrained as management is unable to assert that a reversal of revenue would not be possible. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaboration agreements. The Company receives payments from its customers based on billing schedules established in each contract. The Company’s contract liabilities consist of deferred revenue. Upfront payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. The following table presents changes in the Company’s contract liabilities during the three months ended March 31, 2018 (in thousands): Balance at Beginning of Period Additions Deductions Balance at End of Period Three months ended March 31, 2018 Contract liabilities: Deferred revenue $ 59,868 $ 1,000 $ (5,474 ) $ 55,394 During the three months ended March 31, 2018, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Revenue recognized in the period from: Three Months Ended March 31, 2018 Amounts included in the contract liability at the beginning of the period $ 5,474 Three Months Ended March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Collaboration revenue $ 7,469 $ 7,674 $ (205 ) Operating loss (22,430 ) (22,225 ) (205 ) Net loss $ (21,356 ) $ (21,151 ) $ (205 ) Net loss per share, basic and diluted $ (0.51 ) $ (0.50 ) $ (0.01 ) March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Liabilities: Deferred revenue - current $ 17,062 $ 20,404 $ (3,342 ) Deferred revenue - noncurrent 38,332 40,216 (1,884 ) Stockholders' equity: Accumulated deficit $ (137,038 ) $ (142,264 ) $ 5,226 Costs to obtain and fulfill a contract The Company did not incur any expenses to obtain collaboration agreements and costs to fulfill those contracts do not generate or enhance resources of the Company. As such, no costs to obtain or fulfill a contract have been capitalized in any period. The Company has applied the new standard to all of its contracts. Recent Accounting Pronouncements In May 2014, the FASB issued ASC 606, which superseded existing revenue recognition guidance. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 effective on January 1, 2018 using the modified retrospective method. Please see the above “Revenue Recognition” section for a discussion of the Company’s updated policies related to revenue recognition and accounting for costs to obtain and fulfill a customer contract. Impact of Adoption The Company adopted ASC 606 using the modified retrospective method. The cumulative effect of applying the new guidance to all contracts with customers that were not completed as of January 1, 2018 was recorded as an adjustment to accumulated deficit as of the adoption date. As a result of applying the modified retrospective method to adopt the new guidance, the following adjustments were made to accounts on the consolidated balance sheet as of January 1, 2018: Consolidated Balance Sheet January 1, 2018 (in thousands) Pre-Adoption ASC 606 Adjustment Post-Adoption Current portion of deferred revenue $ 21,188 $ (2,769 ) $ 18,419 Deferred revenue, net of current portion 44,111 (2,662 ) 41,449 Accumulated deficit (121,113 ) 5,431 (115,682 ) In February 2016, the FASB issued ASU No. 2016-02, Leases Leases .

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The Company classifies fair value based measurements using a three-level hierarchy that prioritizes the inputs used to measure fair value. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1, quoted market prices in active markets for identical assets or liabilities; Level 2, observable inputs other than quoted market prices included in Level 1, such as quoted market prices for markets that are not active or other inputs that are observable or can be corroborated by observable market data; and Level 3, unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. The Company’s financial instruments as of March 31, 2018 and December 31, 2017 consisted primarily of cash and cash equivalents, accounts receivable and accounts payable. As of March 31, 2018 and December 31, 2017, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of March 31, 2018 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents $ 313,960 $ 313,960 $ — $ — Total $ 313,960 $ 313,960 $ — $ — Fair Value as of December 31, 2017 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents $ 330,896 $ 330,896 $ — $ — Total $ 330,896 $ 330,896 $ — $ — The Company estimates the fair value of its cash equivalents using quoted market prices in active markets. Other financial instruments, including accounts receivable and accounts payable, are carried at cost, which approximate fair value due to the short duration and term to maturity.

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2018
Payables And Accruals [Abstract]
Accrued Expenses	4. Accrued Expenses Accrued expenses consisted of the following: March 31, December 31, 2018 2017 (In thousands) Employee compensation and benefits $ 2,760 $ 4,773 Research and development and professional expenses 3,845 3,226 Accrued expenses $ 6,605 $ 7,999

Collaborations

Collaborations	3 Months Ended
	Mar. 31, 2018
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborations	5. Collaborations Novartis Institutes for BioMedical Research In December 2014, the Company entered into a strategic collaboration agreement (the “Novartis Agreement”) with Novartis Institutes for Biomedical Research, Inc. (“Novartis”), primarily focused on the development of new ex vivo . Agreement Structure Under the terms of the collaboration, the Company and Novartis ex vivo The Company has the right to choose a limited number of HSC targets for its exclusive development and commercialization per the specified selection schedule. Following these selections by Novartis and the Company, Novartis may obtain rights to research an additional limited number of HSC targets on a non-exclusive basis. The Company also agreed to collaborate with Novartis on research activities for CAR-T cell targets pursuant to a CAR-T cell program research plan approved by the CAR-T cell subcommittee of the collaboration’s joint steering committee. After completion of the activities contemplated by the CAR-T cell program research plan, Novartis will assume sole responsibility for developing any products arising from that research plan and will be responsible for additional costs and expenses of developing, manufacturing and commercializing its selected research targets. Novartis is required to use commercially reasonable efforts to research, develop or commercialize at least one CAR-T cell product directed to each of its selected CAR-T cell targets. In the last two years of the five-year collaboration term, Novartis will have the option to select a limited number of targets for research, development and commercialization of in vivo in vivo in vivo in vivo Novartis’ in vivo target selections are subject to certain restrictions, including that the targets, or all targets within a limited number of organs: (i) have not already been reserved by the Company pursuant to our limited right to do so under the agreement; (ii) are not the subject of a collaboration or pending collaboration with a third party; and (iii) are not the subject of ongoing or planned research and development by the Company The Company received an upfront technology access payment from Novartis of $10.0 million in January 2015 and is entitled to additional technology access fees of $20.0 million and quarterly research payments of $1.0 million, or up to $20.0 million in the aggregate, during the five-year research term. For each product under the collaboration, subject to certain conditions, the Company may be eligible to receive (i) up to $30.3 million in development milestones, including for the filing of an investigational new drug (“IND”) application and for the dosing of the first patient in each of Phase IIa, Phase IIb and Phase III clinical trials, (ii) up to $50.0 million in regulatory milestones for the product’s first indication, including regulatory approvals in the U.S. and European Union (“EU”), (iii) up to $50.0 million in regulatory milestones for the product’s second indication, if any, including U.S. and EU regulatory approvals, (iv) royalties on net sales in the mid-single digits, and (v) net sales milestone payments of up to $100.0 million. The Company may also be eligible to receive payments for: (i) each additional HSC target selected by Novartis beyond its initial defined allocation, (ii) each in vivo considered whether the Unit Purchase Agreement would be subject to combination with the Novartis Agreement and determined that they should be combined because the terms of these arrangements are closely interrelated and were negotiated contemporaneously. The Unit Purchase Agreement and the Novartis Agreement are collectively referred to herein as the “Novartis Arrangement” The Company assessed the Novartis Arrangement in accordance with ASC 606. The Company evaluated the promised goods and services under the Novartis Arrangement and determined that the Novartis Arrangement included two performance obligations: (1) a combined performance obligation representing a series of distinct goods and services including the licenses to research, develop and commercialize HSC products and their associated research activities and the licenses to research, develop and commercialize CAR-T cell products and their associated research activities; and (2) the preferred units. Under the Novartis Arrangement, the Company determined that the transaction price was $59.0 million consisting of the following consideration: (1) the upfront technology access payment of $10.0 million; (2) the additional technology access fees of $20.0 million; (3) the Company’s estimate of variable consideration of $20.0 million related to the quarterly research payments; and (4) the payment for the preferred units of $9.0 million. None of the clinical or regulatory milestones were included in the transaction price, as all milestone amounts were fully constrained. As part of its evaluation of the constraint, the Company considered numerous factors, including that receipt of the milestones is outside the control of the Company and contingent upon future regulatory progress and the licensee’s efforts. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur as they were determined to relate predominantly to the licenses granted to Novartis and therefore have also been excluded from the transaction price. The Company will re-evaluate the transaction price in each reporting period and when events whose outcomes are resolved or other changes in circumstances occur. The Company first allocated $11.6 million of the transaction price to the preferred units to record the preferred units purchased by Novartis at fair value. The Company then allocated the remaining $47.4 million of the transaction price to the remaining combined performance obligation of the licenses and associated research activities for HSC and CAR-T cell products. Revenue allocated to the combined performance obligation of the licenses and associated research activities for HSC and CAR-T cell products is being recognized on a straight-line basis over a period of five years, which, in management’s judgment, is the best measure of progress towards satisfying the performance obligation and represents the Company’s best estimate of the period of the obligation. Collaboration Revenue Through March 31, 2018, excluding amounts allocated to Novartis’ purchase of the Company’s Class A-1 and Class A-2 Preferred Units, the Company had recorded a total of $35.4 million in cash and accounts receivable under the Novartis Arrangement. Through March 31, 2018, the Company has recognized $30.9 million of collaboration revenue, including $2.4 million and $2.2 million during the three months ended March 31, 2018 and 2017, respectively. As of March 31, 2018, there was approximately $16.4 million of the aggregate transaction price remaining to be recognized, which will be recognized through December 2019. As of March 31, 2018 and December 31, 2017, the Company had accounts receivable of $1.0 million and $6.0 million, respectively, related to this agreement. As of March 31, 2018 and December 31, 2017, the Company had deferred revenue of $4.4 million and $11.2 million, respectively, related to this agreement. Amounts for 2018 are reflective of accounting under ASC 606 and amounts for 2017 are reflective of accounting under ASC 605 and therefore may not be comparable. Regeneron Pharmaceuticals, Inc. In April 2016, the Company entered into a license and collaboration agreement (the “Regeneron Agreement”) with Regeneron Pharmaceuticals, Inc. (“Regeneron”). The agreement includes a product component to research, develop and commercialize CRISPR/Cas-based therapeutic products primarily focused on genome editing in the liver as well as a technology collaboration component, pursuant to which the Company and Regeneron will engage in research and development activities aimed at discovering and developing novel technologies and improvements to CRISPR/Cas technology to enhance the Company’s gene editing platform. Under this agreement, the Company also may access the Regeneron Genetics Center and proprietary mouse models to be provided by Regeneron for a limited number of the Company’s liver programs. Agreement Structure Under the terms of the collaboration, the Company and Regeneron have agreed to a target selection process, whereby Regeneron may obtain exclusive rights for up to 10 targets to be chosen by Regeneron during the collaboration term, subject to various adjustments and limitations set forth in the agreement. Of these 10 total targets, Regeneron may select up to five non-liver targets, while the remaining targets must be focused in the liver. At the inception of the agreement, Regeneron selected the first of its 10 targets, which will be subject to a co-development and co-commercialization arrangement between the Company and Regeneron. The Company retains the exclusive right to solely develop products for certain indications. During the target selection process, the Company has the right to choose additional liver targets for its own development using commercially reasonable efforts. Certain targets that either the Company or Regeneron select may be subject to further co-development and co-commercialization arrangements at the Company’s or Regeneron’s option, as applicable, which either can exercise pursuant to defined conditions. In addition, subject to certain restrictions, Regeneron will be able to replace a limited number of targets with substitute targets upon the payment of a specified replacement fee, in which case exclusive rights to the replaced target revert to the Company. Regeneron’s target selections are subject to certain additional restrictions, including that non-liver targets are not the subject of ongoing or planned research and development by the Company or are not the subject of a collaboration or pending collaboration with a third party. Research activities under the collaboration will be governed by evaluation and research and development plans that will outline the parties’ responsibilities under, anticipated timelines of and budgets for, the various programs. The Company will assist Regeneron with the preliminary evaluation of liver targets, and Regeneron will be responsible for preclinical research and the conduct of clinical development, manufacturing and commercialization of products directed to each of its exclusive targets under the oversight of a joint steering committee. The Company may assist, as requested by Regeneron, with the later discovery and research of product candidates directed to any selected target. For each selected target, Regeneron is required to use commercially reasonable efforts to submit regulatory filings necessary to achieve IND acceptance for at least one product directed to each applicable target, and following IND acceptance for at least one product, to develop and commercialize such product. In connection with this collaboration, Regeneron agreed to purchase $50.0 million of the Company’s common stock in a private placement under a Stock Purchase Agreement (the “Stock Purchase Agreement”) concurrent with the Company’s initial public offering, and the Company received a nonrefundable upfront payment of $75.0 million. In addition, the Company is eligible to earn, on a per-licensed target basis, (i) up to $25.0 million in development milestones, including for the dosing of the first patient in each of Phase I, Phase II and Phase III clinical trials, (ii) up to $110.0 million in regulatory milestones, including for the acceptance of a regulatory filing in the U.S., and U.S. and ex-U.S. regulatory approvals, and (iii) up to $185.0 million in sales-based milestone payments. The Company is also eligible to earn royalties ranging from the high single digits to low teens, in each case, on a per-product basis, which royalties are potentially subject to various reductions and offsets and are further subject to the Company’s existing low- to mid-single-digit royalty obligations under a license agreement with Caribou Biosciences, Inc. (“Caribou”). In addition, Regeneron is obligated to fund 50.0 percent of the research and development costs for the transthyretin amyloidosis program, the first target selected by Regeneron, which will be subject to a co-development and co-commercialization arrangement between the Company and Regeneron. The Company considered whether the Stock Purchase Agreement would be subject to combination with the Regeneron Agreement and determined that they should be combined because the terms of these arrangements are closely interrelated and were negotiated contemporaneously. The Stock Purchase Agreement and the Regeneron Agreement are collectively referred to herein as the “Regeneron Arrangement”. The Company assessed the Regeneron Arrangement in accordance with ASC 606. The Company evaluated the promised goods and services under the Regeneron Arrangement and determined that the Regeneron Arrangement included three performance obligations: (1) a combined performance obligation including the licenses to targets and the associated research activities and evaluation plans; (2) a combined performance obligation including the technology collaboration and associated research activities; and (3) the common stock. Under the Regeneron Arrangement, the Company determined that the transaction price was $125.0 million, consisting of the following consideration: (1) the nonrefundable upfront payment of $75.0 million; and (2) the payment for the common stock of $50.0 million. None of the clinical or regulatory milestones were included in the transaction price, as all milestone amounts were fully constrained. As part its evaluation of the constraint, the Company considered numerous factors, including that receipt of the milestones is outside the control of the Company and contingent upon success in future regulatory progress and the licensee’s efforts. Any consideration related to sales-based milestones and royalties will be recognized when the related sales occur as they were determined to relate predominantly to the licenses granted to Regeneron and therefore have also been excluded from the transaction price. The Company will re-evaluate the transaction price in each reporting period and when events whose outcome are resolved or other changes in circumstances occur . The Company first allocated $50.0 million of the transaction price to the common stock. The common stock was sold at its standalone selling price and the Company concluded that the total discount inherent in the arrangement is entirely attributable to the combined performance obligation including the licenses to targets and associated research activities and evaluation plans and the combined performance obligation including the technology collaboration and associated research activities. As such, the remaining $75.0 million of the transaction price was allocated to the combined performance obligation including the licenses to targets and associated research activities and evaluation plans and the combined performance obligation including the technology collaboration and associated research activities on a relative standalone selling price basis. The Company estimated the standalone selling price of each combined performance obligation by taking into consideration internal estimates of research and development personnel needed to perform the research and development services, estimates of expected cash outflows to third parties for services and supplies, selling prices of comparable transactions and typical gross profit margins. As a result of this evaluation, the Company allocated $63.8 million to the combined performance obligation including the licenses to targets and associated research activities and evaluation plans and $11.2 million to the combined performance obligation including the technology collaboration and associated research activities. The $63.8 million allocated to the combined performance obligation including the licenses to targets and associated research activities and evaluation plans is being recognized on a straight-line basis over the six-year performance period of the arrangement, which, in management’s judgment, is the best measure of progress towards satisfying the performance obligation and represents the Company’s best estimate of the period of the obligation. The $11.2 million allocated to the combined performance obligation including the technology collaboration and associated research activities is being recognized on a straight-line basis over a period beginning with the inception of the technology collaboration in September 2016 through the end of the arrangement, which, in management’s judgment, is the best measure of progress towards satisfying the performance obligation and represents the Company’s best estimate of the period of the obligation . Collaboration Revenue Through March 31, 2018, excluding the amounts allocated to Regeneron’s purchase of common stock, the Company recorded a $75.0 million upfront payment and $6.6 million for research and development services under the Regeneron Arrangement. Through March 31, 2018, the Company has recognized $30.6 million of collaboration revenue, including $5.1 million and $4.1 million during the three months ended March 31, 2018 and 2017, respectively, in the consolidated statements of operations related to this arrangement. As of March 31, 2018, there was approximately $51.0 million of the aggregate transaction price remaining to be recognized, which will be recognized ratably through April 2022. As of March 31, 2018 and December 31, 2017, the Company had deferred revenue of $51.0 million and $54.1 million, respectively, and accounts receivable of $6.5 million and $4.5 million, respectively, related to this arrangement. Agreement Termination Rights The collaboration term ends in April 2022, except that Regeneron may make a one-time payment of $25.0 million to extend the term for an additional two-year period. The agreement will continue until the date when no royalty or other payment obligations are due, unless earlier terminated in accordance with the terms of the agreement. Regeneron’s royalty payment obligations expire on a country-by-country and product-by-product basis upon the later of (i) the expiration of the last valid claim of the royalty-bearing patents covering such product in such country, (ii) 12 years from the first commercial sale of such product in such country, or (iii) the expiration of regulatory exclusivity for such product. The Company may terminate the agreement on a target-by-target basis if Regeneron or any of its affiliates institutes a patent challenge against the Company’s CRISPR/Cas or certain other background patent rights. The Company may also terminate the agreement on a target-by-target basis if Regeneron does not proceed with the development of a product directed to a selected target within specified periods of time. Regeneron may terminate the agreement, without cause, upon 180 days written notice to the Company, either in its entirety or on a target-by-target basis, in which event, certain rights in the terminated targets and associated intellectual property revert to the Company, as described in the agreement. Following such termination, the Company may owe Regeneron royalties, in certain circumstances, up to mid-single digits on any terminated targets that the Company subsequently commercializes on a product-by-product basis for a period of 12 years after the first commercial sale of any such products. Either party may terminate the agreement either in its entirety or with respect to the technology collaboration or one or more of the targets selected by Regeneron, in the event of the other party’s uncured material breach.

Equity-Based Compensation

Equity-Based Compensation	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Equity-Based Compensation	6. Equity-Based Compensation Equity-based compensation expense is classified in the consolidated statements of operations as follows: Three Months Ended March 31, 2018 2017 (In thousands) Research and development $ 2,393 $ 1,503 General and administrative 1,714 1,127 Total $ 4,107 $ 2,630 Restricted Stock The following table summarizes the Company’s restricted stock activity for the three months ended March 31, 2018: Number of Shares Weighted Average Date Fair Value per Share Unvested restricted stock as of January 1, 2018 479,822 $ 0.90 Granted 71,875 23.46 Vested (149,846 ) 0.78 Cancelled (2,022 ) 1.34 Unvested restricted stock as of March 31, 2018 399,829 $ 5.02 As of March 31, 2018, there was $3.3 Stock Options The weighted average grant date fair value of options, estimated as of the grant date using the Black-Scholes option pricing model, was $18.28 Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 Risk-free interest rate 2.5 % 1.9 % Expected life of options 6.0 years 6.0 years Expected volatility of underlying stock 89.4 % 92.6 % Expected dividend yield 0.0 % 0.0 % The following is a summary of stock option activity for the three months ended March 31, 2018: Number of Options Weighted Average Exercise per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at January 1, 2018 4,705,448 $ 12.09 Granted 792,414 24.44 Exercised (709,321 ) 9.47 Forfeited (17,224 ) 14.62 Outstanding at March 31, 2018 4,771,317 $ 14.52 8.68 $ 35,070 Exercisable at March 31, 2018 1,343,841 $ 9.64 7.95 $ 15,420 As of March 31, 2018, there was $39.2

Loss Per Share

Loss Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Loss Per Share	7. Loss Per Share The Company calculates basic (loss) earnings per share by dividing (loss) income allocable to common stockholders by the weighted average number of common shares outstanding. The Company computes diluted (loss) earnings per share after giving consideration to the dilutive effect of stock options and unvested restricted stock that are outstanding during the period, except where such securities would be anti-dilutive. Basic and diluted loss per share attributable to common stockholders was calculated as follows: Three Months Ended March 31, 2018 2017 (In thousands) Net loss $ (21,356 ) $ (12,631 ) Weighted average shares outstanding, basic and diluted 42,043 34,723 Net loss per share attributable to common stockholders, basic and diluted $ (0.51 ) $ (0.36 ) The following common stock equivalents were excluded from the calculation of diluted loss per share because their inclusion would have been anti-dilutive: Periods Ended March 31, 2018 2017 (In thousands) Unvested restricted stock 400 1,175 Stock options 4,771 4,373 Total 5,171 5,548

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	8. Related Party Transactions Caribou Therapeutics In July 2014, the Company issued Caribou Therapeutics Holdco, LLC, a wholly-owned subsidiary of Caribou, 8,110,599 Junior Preferred Units. As a result of this and related transactions, Caribou owned 9.3 percent of the Company’s voting interests as of March 31, 2018. The Company recognized general and administrative expense of $0.2 million patent prosecution, filing and maintenance costs Novartis Institutes for BioMedical Research In connection with its entry into the collaboration and license agreement and related equity transactions with Novartis, the Company issued Novartis 4,761,905 Class A-1 Preferred Units and 2,666,666 Class A-2 Preferred Units. In August 2015, Novartis acquired 761,905 shares of the Company’s Series B Preferred Stock, and in May 2016, Novartis acquired 277,777 shares of the Company’s common stock in a private placement transaction concurrent with the Company’s IPO. As a result of these and subsequent transactions, Novartis collectively owned 9.9% of the Company’s voting interests as of March 31, 2018. The Company recognized collaboration revenue of $2.4 Collaborations

Summary of Significant Accoun14

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Revenue Recognition	Revenue Recognition In May 2014, the Financing Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606) In accordance with ASC 606, revenue is recognized when a customer obtains control of promised goods or services. The amount of revenue recognized reflects the consideration to which the Company expects to be entitled to receive in exchange for these goods and services. To achieve this core principle, the Company applies the following five steps: 1) Identify the contract with the customer A contract with a customer exists when (i) the Company enters into an enforceable contract with a customer that defines each party’s rights regarding the goods or services to be transferred and identifies the related payment terms, (ii) the contract has commercial substance, and (iii) the Company determines that collection of substantially all consideration for goods and services that are transferred is probable based on the customer’s intent and ability to pay the promised consideration. The Company applies judgment in determining the customer’s intent and ability to pay, which is based on a variety of factors including the customer’s historical payment experience, or in the case of a new customer, published credit and financial information pertaining to the customer. 2) Identify the performance obligations in the contract Performance obligations promised in a contract are identified based on the goods and services that will be transferred to the customer that are both capable of being distinct, whereby the customer can benefit from the good or service either on its own or together with other available resources, and are distinct in the context of the contract, whereby the transfer of the good or service is separately identifiable from other promises in the contract. To the extent a contract includes multiple promised goods and services, the Company must apply judgment to determine whether promised goods and services are both capable of being distinct and distinct in the context of the contract. If these criteria are not met, the promised goods and services are accounted for as a combined performance obligation. 3) The transaction price is determined based on the consideration to which the Company will be entitled in exchange for transferring goods and services to the customer. To the extent the transaction price includes variable consideration, the Company estimates the amount of variable consideration that should be included in the transaction price utilizing either the expected value method or the most likely amount method, depending on the nature of the variable consideration. Variable consideration is included in the transaction price if, in the Company’s judgment, it is probable that a significant future reversal of cumulative revenue under the contract will not occur. Any estimates, including the effect of the constraint on variable consideration, are evaluated at each reporting period for any changes. Determining the transaction price requires significant judgment, which is discussed in further detail for each of the Company’s collaboration agreements in Note 5. In addition, neither of the Company’s contracts as of March 31, 2018 contained a significant financing component. 4) Allocate the transaction price to performance obligations in the contract If the contract contains a single performance obligation, the entire transaction price is allocated to the single performance obligation. However, if a series of distinct services that are substantially the same qualifies as a single performance obligation in a contract with variable consideration, the Company must determine if the variable consideration is attributable to the entire contract or to a specific part of the contract. Contracts that contain multiple performance obligations require an allocation of the transaction price to each performance obligation on a relative standalone selling price basis unless the transaction price is variable and meets the criteria to be allocated entirely to a performance obligation or to a distinct service that forms part of a single performance obligation. The consideration to be received is allocated among the separate performance obligations based on relative standalone selling prices. The Company typically determines standalone selling prices using an adjusted market assessment approach model. 5) Recognize revenue when or as the Company satisfies a performance obligation The Company satisfies performance obligations either over time or at a point in time. Revenue is recognized over time if either (i) the customer simultaneously receives and consumes the benefits provided by the entity’s performance, (ii) the entity’s performance creates or enhances an asset that the customer controls as the asset is created or enhanced, or (iii) the entity’s performance does not create an asset with an alternative use to the entity and the entity has an enforceable right to payment for performance completed to date. If the entity does not satisfy a performance obligation over time, the related performance obligation is satisfied at a point in time by transferring the control of a promised good or service to a customer. Examples of control are using the asset to produce goods or services, enhance the value of other assets, or settle liabilities, and holding or selling the asset. As of March 31, 2018, the Company’s only revenue recognized is related to collaboration agreements with third parties. As discussed in further detail in Note 5, the Company enters into out-licensing agreements which are within the scope of ASC 606, under which it licenses certain rights to its product candidates to third parties. The terms of these arrangements typically include payment to the Company of one or more of the following: nonrefundable, upfront fees; development, regulatory, and commercial milestone payments; research and development funding payments; and royalties on the net sales of licensed products. Each of these payments results in collaboration revenues, except for revenues from royalties on the net sales of licensed products, which are classified as royalty revenues. Licenses of intellectual property: If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenues from consideration allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the licenses. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Milestone payments: At the inception of each arrangement that includes development milestone payments, the Company evaluates the probability of reaching the milestones and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur in the future, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received and therefore revenue recognized is constrained as management is unable to assert that a reversal of revenue would not be possible. The transaction price is then allocated to each performance obligation on a relative standalone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. At the end of each subsequent reporting period, the Company re-evaluates the probability of achievement of such development milestones and any related constraint, and if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect collaboration revenues and earnings in the period of adjustment. Royalties: For arrangements that include sales-based royalties, including milestone payments based on levels of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its collaboration agreements. The Company receives payments from its customers based on billing schedules established in each contract. The Company’s contract liabilities consist of deferred revenue. Upfront payments and fees are recorded as deferred revenue upon receipt or when due, and may require deferral of revenue recognition to a future period until the Company performs its obligations under these arrangements. The following table presents changes in the Company’s contract liabilities during the three months ended March 31, 2018 (in thousands): Balance at Beginning of Period Additions Deductions Balance at End of Period Three months ended March 31, 2018 Contract liabilities: Deferred revenue $ 59,868 $ 1,000 $ (5,474 ) $ 55,394 During the three months ended March 31, 2018, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Revenue recognized in the period from: Three Months Ended March 31, 2018 Amounts included in the contract liability at the beginning of the period $ 5,474 Three Months Ended March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Collaboration revenue $ 7,469 $ 7,674 $ (205 ) Operating loss (22,430 ) (22,225 ) (205 ) Net loss $ (21,356 ) $ (21,151 ) $ (205 ) Net loss per share, basic and diluted $ (0.51 ) $ (0.50 ) $ (0.01 ) March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Liabilities: Deferred revenue - current $ 17,062 $ 20,404 $ (3,342 ) Deferred revenue - noncurrent 38,332 40,216 (1,884 ) Stockholders' equity: Accumulated deficit $ (137,038 ) $ (142,264 ) $ 5,226 Costs to obtain and fulfill a contract The Company did not incur any expenses to obtain collaboration agreements and costs to fulfill those contracts do not generate or enhance resources of the Company. As such, no costs to obtain or fulfill a contract have been capitalized in any period. The Company has applied the new standard to all of its contracts.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the FASB issued ASC 606, which superseded existing revenue recognition guidance. The standard’s core principle is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 effective on January 1, 2018 using the modified retrospective method. Please see the above “Revenue Recognition” section for a discussion of the Company’s updated policies related to revenue recognition and accounting for costs to obtain and fulfill a customer contract. Impact of Adoption The Company adopted ASC 606 using the modified retrospective method. The cumulative effect of applying the new guidance to all contracts with customers that were not completed as of January 1, 2018 was recorded as an adjustment to accumulated deficit as of the adoption date. As a result of applying the modified retrospective method to adopt the new guidance, the following adjustments were made to accounts on the consolidated balance sheet as of January 1, 2018: Consolidated Balance Sheet January 1, 2018 (in thousands) Pre-Adoption ASC 606 Adjustment Post-Adoption Current portion of deferred revenue $ 21,188 $ (2,769 ) $ 18,419 Deferred revenue, net of current portion 44,111 (2,662 ) 41,449 Accumulated deficit (121,113 ) 5,431 (115,682 ) In February 2016, the FASB issued ASU No. 2016-02, Leases Leases .

Summary of Significant Accoun15

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Changes in Contract Liabilities	The following table presents changes in the Company’s contract liabilities during the three months ended March 31, 2018 (in thousands): Balance at Beginning of Period Additions Deductions Balance at End of Period Three months ended March 31, 2018 Contract liabilities: Deferred revenue $ 59,868 $ 1,000 $ (5,474 ) $ 55,394
Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance	During the three months ended March 31, 2018, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Revenue recognized in the period from: Three Months Ended March 31, 2018 Amounts included in the contract liability at the beginning of the period $ 5,474
Summary of Impact of Adoption to Consolidated Statement of Income and Balance Sheet	The following table shows the impact of adoption to our consolidated statement of income and balance sheet: Three Months Ended March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Collaboration revenue $ 7,469 $ 7,674 $ (205 ) Operating loss (22,430 ) (22,225 ) (205 ) Net loss $ (21,356 ) $ (21,151 ) $ (205 ) Net loss per share, basic and diluted $ (0.51 ) $ (0.50 ) $ (0.01 ) March 31, 2018 Impact of changes in accounting policies As Reported Balances without adoption of ASC 606 Effect of Change Higher/(Lower) Liabilities: Deferred revenue - current $ 17,062 $ 20,404 $ (3,342 ) Deferred revenue - noncurrent 38,332 40,216 (1,884 ) Stockholders' equity: Accumulated deficit $ (137,038 ) $ (142,264 ) $ 5,226
Schedule of Adjustments to Consolidated Balance Sheet Due to Adoption of New Guidance	As a result of applying the modified retrospective method to adopt the new guidance, the following adjustments were made to accounts on the consolidated balance sheet as of January 1, 2018: Consolidated Balance Sheet January 1, 2018 (in thousands) Pre-Adoption ASC 606 Adjustment Post-Adoption Current portion of deferred revenue $ 21,188 $ (2,769 ) $ 18,419 Deferred revenue, net of current portion 44,111 (2,662 ) 41,449 Accumulated deficit (121,113 ) 5,431 (115,682 )

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Summary of Financial Assets Recognized at Fair Value on Recurring Basis	As of March 31, 2018 and December 31, 2017, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of March 31, 2018 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents $ 313,960 $ 313,960 $ — $ — Total $ 313,960 $ 313,960 $ — $ — Fair Value as of December 31, 2017 Total Level 1 Level 2 Level 3 (In thousands) Cash equivalents $ 330,896 $ 330,896 $ — $ — Total $ 330,896 $ 330,896 $ — $ —

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2018
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: March 31, December 31, 2018 2017 (In thousands) Employee compensation and benefits $ 2,760 $ 4,773 Research and development and professional expenses 3,845 3,226 Accrued expenses $ 6,605 $ 7,999

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Equity-Based Compensation Expense	Equity-based compensation expense is classified in the consolidated statements of operations as follows: Three Months Ended March 31, 2018 2017 (In thousands) Research and development $ 2,393 $ 1,503 General and administrative 1,714 1,127 Total $ 4,107 $ 2,630
Summary of Restricted Stock Activity	The following table summarizes the Company’s restricted stock activity for the three months ended March 31, 2018: Number of Shares Weighted Average Date Fair Value per Share Unvested restricted stock as of January 1, 2018 479,822 $ 0.90 Granted 71,875 23.46 Vested (149,846 ) 0.78 Cancelled (2,022 ) 1.34 Unvested restricted stock as of March 31, 2018 399,829 $ 5.02
Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted	Key assumptions used to apply this pricing model were as follows: Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 Risk-free interest rate 2.5 % 1.9 % Expected life of options 6.0 years 6.0 years Expected volatility of underlying stock 89.4 % 92.6 % Expected dividend yield 0.0 % 0.0 %
Summary of Stock Option Activity	The following is a summary of stock option activity for the three months ended March 31, 2018: Number of Options Weighted Average Exercise per Share Weighted Average Remaining Contractual Term Aggregate Intrinsic Value (In years) (In thousands) Outstanding at January 1, 2018 4,705,448 $ 12.09 Granted 792,414 24.44 Exercised (709,321 ) 9.47 Forfeited (17,224 ) 14.62 Outstanding at March 31, 2018 4,771,317 $ 14.52 8.68 $ 35,070 Exercisable at March 31, 2018 1,343,841 $ 9.64 7.95 $ 15,420

Loss Per Share (Tables)

Loss Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	Basic and diluted loss per share attributable to common stockholders was calculated as follows: Three Months Ended March 31, 2018 2017 (In thousands) Net loss $ (21,356 ) $ (12,631 ) Weighted average shares outstanding, basic and diluted 42,043 34,723 Net loss per share attributable to common stockholders, basic and diluted $ (0.51 ) $ (0.36 )
Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share	The following common stock equivalents were excluded from the calculation of diluted loss per share because their inclusion would have been anti-dilutive: Periods Ended March 31, 2018 2017 (In thousands) Unvested restricted stock 400 1,175 Stock options 4,771 4,373 Total 5,171 5,548

Summary of Significant Accoun20

Summary of Significant Accounting Policies - Summary of Changes in Contract Liabilities (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	$ 59,868
Deferred revenue, Additions	1,000
Deferred revenue, Deductions	(5,474)
Deferred revenue, Balance at End of Period	$ 55,394

Summary of Significant Accoun21

Summary of Significant Accounting Policies - Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue From Contract With Customer [Abstract]
Amounts included in the contract liability at the beginning of the period	$ 5,474

Summary of Significant Accoun22

Summary of Significant Accounting Policies - Summary of Impact of Adoption to Consolidated Statement of Income and Balance Sheet (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Jan. 01, 2018	Dec. 31, 2017
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Collaboration revenue	$ 7,469	$ 6,215
Operating loss	(22,430)	(12,948)
Net loss	$ (21,356)	$ (12,631)
Net loss per share, basic and diluted	$ (0.51)	$ (0.36)
Liabilities:
Deferred revenue - current	$ 17,062			$ 21,188
Deferred revenue - noncurrent	38,332			44,111
Stockholders' Equity:
Accumulated deficit	(137,038)			$ (121,113)
Accounting Standards Update (“ASU”) No. 2014-09 [Member]
Liabilities:
Deferred revenue - current			$ 18,419
Deferred revenue - noncurrent			41,449
Stockholders' Equity:
Accumulated deficit			(115,682)
Accounting Standards Update (“ASU”) No. 2014-09 [Member] | Balances without Adoption of ASC 606 [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Collaboration revenue	7,674
Operating loss	(22,225)
Net loss	$ (21,151)
Net loss per share, basic and diluted	$ (0.50)
Liabilities:
Deferred revenue - current	$ 20,404
Deferred revenue - noncurrent	40,216
Stockholders' Equity:
Accumulated deficit	(142,264)
Accounting Standards Update (“ASU”) No. 2014-09 [Member] | Effect of Change Higher/(Lower) [Member]
Revenue Initial Application Period Cumulative Effect Transition [Line Items]
Collaboration revenue	(205)
Operating loss	(205)
Net loss	$ (205)
Net loss per share, basic and diluted	$ (0.01)
Liabilities:
Deferred revenue - current	$ (3,342)		(2,769)
Deferred revenue - noncurrent	(1,884)		(2,662)
Stockholders' Equity:
Accumulated deficit	$ 5,226		$ 5,431

Summary of Significant Accoun23

Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2018USD ($)
Accounting Policies [Abstract]
Expenses incurred to obtain collaboration agreements and costs to fulfill contracts	$ 0
Costs to obtain or fulfill contract capitalized	$ 0

Summary of Significant Accoun24

Summary of Significant Accounting Policies - Schedule of Adjustments to Consolidated Balance Sheet Due to Adoption of New Guidance (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Item Effected [Line Items]
Current portion of deferred revenue	$ 17,062		$ 21,188
Deferred revenue, net of current portion	38,332		44,111
Accumulated deficit	(137,038)		$ (121,113)
Accounting Standards Update (“ASU”) No. 2014-09 [Member]
Item Effected [Line Items]
Current portion of deferred revenue		$ 18,419
Deferred revenue, net of current portion		41,449
Accumulated deficit		(115,682)
Accounting Standards Update (“ASU”) No. 2014-09 [Member] | ASC 606 Adjustment [Member]
Item Effected [Line Items]
Current portion of deferred revenue	(3,342)	(2,769)
Deferred revenue, net of current portion	(1,884)	(2,662)
Accumulated deficit	$ 5,226	$ 5,431

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Recognized at Fair Value on Recurring Basis (Detail) - Fair Value on Recurring Basis [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	$ 313,960	$ 330,896
Total	313,960	330,896
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	313,960	330,896
Total	$ 313,960	$ 330,896

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Payables And Accruals [Abstract]
Employee compensation and benefits	$ 2,760	$ 4,773
Research and development and professional expenses	3,845	3,226
Accrued expenses	$ 6,605	$ 7,999

Collaborations - Additional Inf

Collaborations - Additional Information (Detail)	1 Months Ended		3 Months Ended		24 Months Ended	40 Months Ended
	Apr. 30, 2016USD ($)	Jan. 31, 2015USD ($)	Mar. 31, 2018USD ($)PerformanceObligation	Mar. 31, 2017USD ($)	Mar. 31, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 7,469,000	$ 6,215,000
Novartis [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development based milestone payments under agreement		$ 30,300,000
Regulatory based milestone payments for first indication		50,000,000
Regulatory based milestone payments for second indication		50,000,000
Sales based milestone payments under agreement		100,000,000
Novartis [Member] | Novartis Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue Additions		10,000,000
Technology access fees		20,000,000
Quarterly research payments		$ 1,000,000
Research term		5 years
Novartis [Member] | Novartis Agreement [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Total research funding		$ 20,000,000
Novartis [Member] | Unit Purchase Agreement [Member] | Class A Preferred Units [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Proceeds from issuance of preferred stock		$ 9,000,000
Novartis [Member] | Novartis Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue Additions			10,000,000			$ 35,400,000
Technology access fees			20,000,000		$ 20,000,000	20,000,000
Quarterly research payments			20,000,000		20,000,000	20,000,000
Proceeds from issuance of preferred stock			$ 9,000,000
Number of performance obligations | PerformanceObligation			2
Transaction price			$ 59,000,000
Transaction price allocated to preferred units purchased at fair value			11,600,000
Collaboration revenue			2,400,000	2,200,000		30,900,000
Aggregate transaction price remaining to be recognized			$ 16,400,000		16,400,000	16,400,000
Aggregate transaction price remaining to be recognized, period			through December 2019
Accounts receivable			$ 1,000,000		1,000,000	1,000,000	$ 6,000,000
Deferred revenue			4,400,000		4,400,000	4,400,000	11,200,000
Novartis [Member] | Novartis Arrangement [Member] | HSC and CAR-T Cell Products [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Remaining transaction price allocated to combined performance obligation of licenses and associated research activities			$ 47,400,000
Combined performance obligation of licenses and associated research activities, revenue recognition period			5 years
Regeneron Pharmaceuticals Inc. [Member] | Stock Purchase Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Purchase of common stock through private placement	$ 50,000,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue Additions	$ 75,000,000
Percentage of obligated fund on research and development costs	50.00%
One time collaboration payment	$ 25,000,000
Collaboration term extension period	2 years
Royalty payment obligation expiration period	12 years
Termination period of agreement	180 days
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development based milestone payments under agreement	$ 25,000,000
Sales based milestone payments under agreement	185,000,000
Regulatory based milestone payments under agreement	$ 110,000,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Arrangement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred Revenue Additions			$ 75,000,000		75,000,000
Number of performance obligations | PerformanceObligation			3
Transaction price			$ 125,000,000
Collaboration revenue			5,100,000	$ 4,100,000	30,600,000
Aggregate transaction price remaining to be recognized			$ 51,000,000		51,000,000	51,000,000
Aggregate transaction price remaining to be recognized, period			through April 2022
Deferred revenue			$ 51,000,000		51,000,000	51,000,000	54,100,000
Purchase of common stock through private placement			50,000,000
Transaction price allocated to common stock			50,000,000
Remaining transaction price allocated to combined performance obligation			75,000,000
Amount allocated to licenses to targets and associated research activities and evaluation plans			63,800,000
Amount allocated to technology collaboration and associated research activities			$ 11,200,000
Licenses to targets and associated research activities and evaluation plans performance period			6 years
Accounts receivable			$ 6,500,000		6,500,000	$ 6,500,000	$ 4,500,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Arrangement [Member] | Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue					$ 6,600,000

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 4,107	$ 2,630
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	2,393	1,503
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 1,714	$ 1,127

Equity-Based Compensation - Sum

Equity-Based Compensation - Summary of Restricted Stock Activity (Detail)	3 Months Ended
	Mar. 31, 2018$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Unvested, Beginning balance | shares	479,822
Number of Shares, Granted | shares	71,875
Number of Shares, Vested | shares	(149,846)
Number of Shares, Cancelled | shares	(2,022)
Number of Shares, Unvested, Ending balance | shares	399,829
Weighted Average Grant Date Fair Value per Share, Unvested, Beginning balance | $ / shares	$ 0.90
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	23.46
Weighted Average Grant Date Fair Value per Share, Vested | $ / shares	0.78
Weighted Average Grant Date Fair Value per Share, Cancelled | $ / shares	1.34
Weighted Average Grant Date Fair Value per Share, Unvested, Ending balance | $ / shares	$ 5.02

Equity-Based Compensation - Add

Equity-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized equity-based compensation expense related to restricted stock	$ 3.3
Weighted average grant date fair value per share	$ 18.28	$ 10.38
Unrecognized compensation cost related to stock options	$ 39.2
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of unrecognized compensation costs	1 year 8 months 12 days
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average period of unrecognized compensation costs	3 years 1 month 6 days

Equity-Based Compensation - S31

Equity-Based Compensation - Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted (Detail)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk-free interest rate	2.50%	1.90%
Expected life of options	6 years	6 years
Expected volatility of underlying stock	89.40%	92.60%
Expected dividend yield	0.00%	0.00%

Equity-Based Compensation - S32

Equity-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)$ / sharesshares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Options, Outstanding, Beginning Balance | shares	4,705,448
Number of options, Granted | shares	792,414
Number of options, Exercised | shares	(709,321)
Number of options, Forfeited | shares	(17,224)
Number of Options, Outstanding, Ending Balance | shares	4,771,317
Number of Options, Exercisable | shares	1,343,841
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance | $ / shares	$ 12.09
Weighted Average Exercise Price per Share, Granted | $ / shares	24.44
Weighted Average Exercise Price per Share, Exercised | $ / shares	9.47
Weighted Average Exercise Price per Share, Forfeited | $ / shares	14.62
Weighted Average Exercise Price per Share, Outstanding, Ending Balance | $ / shares	14.52
Weighted Average Exercise Price per Share, Exercisable | $ / shares	$ 9.64
Weighted Average Remaining Contractual Term, Outstanding	8 years 8 months 4 days
Weighted Average Remaining Contractual Term, Exercisable	7 years 11 months 12 days
Aggregate Intrinsic Value, Outstanding | $	$ 35,070
Aggregate Intrinsic Value, Exercisable | $	$ 15,420

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Earnings Per Share [Abstract]
Net loss	$ (21,356)	$ (12,631)
Weighted average shares outstanding, basic and diluted	42,043	34,723
Net loss per share attributable to common stockholders, basic and diluted	$ (0.51)	$ (0.36)

Loss Per Share - Potential Dilu

Loss Per Share - Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	5,171	5,548
Unvested Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	400	1,175
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	4,771	4,373

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended
	May 31, 2016	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Aug. 31, 2015	Jul. 31, 2014
Related Party Transaction [Line Items]
General and administrative expenses		$ 7,406	$ 5,732
Collaboration revenue		$ 7,469	$ 6,215
Caribou [Member]
Related Party Transaction [Line Items]
Junior preferred units issued						8,110,599
Percentage of shares owned		9.30%
General and administrative expenses		$ 200
Percentage of related party obligation		30.00%	30.00%
Novartis [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Percentage of shares owned		9.90%
Common stock, shares acquired	277,777
Collaboration revenue		$ 2,400	$ 2,200
Accounts receivable		1,000		$ 6,000
Deferred revenue		$ 4,400		$ 11,200
Novartis [Member] | Class A-1 Preferred Units [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Junior preferred units issued						4,761,905
Novartis [Member] | Class A-2 Preferred Units [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Junior preferred units issued						2,666,666
Novartis [Member] | Series B Preferred Stock [Member] | Collaborative Arrangement [Member]
Related Party Transaction [Line Items]
Preferred stock, shares acquired					761,905