CRISPR Therapeutics (CRSP) 10-Q 22 Nov 16 2016 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2016	Nov. 21, 2016
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	Q3
Trading Symbol	crspr
Entity Registrant Name	CRISPR THERAPEUTICS AG
Entity Central Index Key	1,674,416
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		39,808,801

Consolidated Balance Sheets

Consolidated Balance Sheets SFr in Thousands, $ in Thousands	Sep. 30, 2016USD ($)	Sep. 30, 2016CHF (SFr)	Dec. 31, 2015USD ($)	Dec. 31, 2015CHF (SFr)
Current assets:
Cash	$ 228,613		$ 155,961
Accounts receivable, including related party amounts of $459 and $0 as of September 30, 2016 and December 31, 2015, respectively (see Note 13)	2,092		339
Prepaid expenses and other current assets	946		540
Total current assets	231,651		156,840
Property and equipment, net	3,862		1,328
Equity method investment	35,686
Intangible assets, net	413		454
Restricted cash	3,153		700
Other non-current assets	3,888		101
Total assets	278,653		159,423
Current liabilities:
Accounts payable	1,943		1,584
Accrued expenses	12,402		8,430
Accrued tax liabilities	82		81
Deferred gain	63,608
Other current liabilities	62		60
Total current liabilities	78,097		10,155
Convertible loan, including accrued interest of $0 and $97 as of September 30, 2016 and December 31, 2015, respectively			38,336
Deferred revenue	76,949		75,090
Other non-current liabilities	574		445
Total liabilities	155,620		124,026
Commitments and contingencies (Note 7)
Shareholders' deficit:
Common shares, CHF 0.03 par value, 5,662,126 shares authorized and issued, and 5,307,845 shares outstanding, and 5,528,079 shares authorized, issued and outstanding in share capital at September 30, 2016 and December 31, 2015, respectively; 38,453,593 and 2,444,364 shares in conditional capital at September 30, 2016 and December 31, 2015, respectively	174		181
Treasury shares, at cost; 274,184 shares at September 30, 2016 and no shares at December 31, 2015	0	SFr 0	0	SFr 0
Additional paid-in capital	11,553		4,636
Accumulated deficit	(74,182)		(33,906)
Accumulated other comprehensive loss	(26)		(8)
Total CRISPR Therapeutics AG shareholders' deficit	(62,481)		(29,097)
Noncontrolling interest	(51)		(27)
Total shareholders' deficit	(62,532)		(29,124)
Total liabilities, redeemable convertible preferred shares and shareholders' deficit	278,653		159,423
Series A-1 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred shares:
Redeemable convertible preferred shares	1,169		1,169
Series A-2 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred shares:
Redeemable convertible preferred shares	10,394		10,394
Series A-3 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred shares:
Redeemable convertible preferred shares	45,368		22,518
Series B Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred shares:
Redeemable convertible preferred shares	$ 128,634		$ 30,440

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) SFr in Thousands, $ in Thousands	Sep. 30, 2016USD ($)shares	Sep. 30, 2016CHF (SFr)SFr / sharesshares	Jul. 31, 2016SFr / shares	Jun. 30, 2016shares	Jan. 31, 2016shares	Dec. 31, 2015USD ($)shares	Dec. 31, 2015CHF (SFr)SFr / sharesshares	May 31, 2015shares	Apr. 30, 2015shares	Apr. 30, 2014$ / sharesshares	Apr. 30, 2014SFr / sharesshares	Oct. 31, 2013$ / sharesshares	Oct. 31, 2013SFr / sharesshares
Accounts receivable, related party amount, current | $	$ 459					$ 0
Convertible loan, accrued interest | $	$ 0					$ 97
Redeemable convertible preferred stock, par value | SFr / shares		SFr 0.03					SFr 0.03
Redeemable convertible preferred stock, shares outstanding	27,135,884	27,135,884				18,837,024	18,837,024
Common stock, par value | SFr / shares		SFr 0.03	SFr 0.03				SFr 0.03
Common stock, shares authorized	5,662,126	5,662,126				5,528,079	5,528,079
Common stock, shares issued	5,662,126	5,662,126				5,528,079	5,528,079
Common stock, shares outstanding	5,307,845	5,307,845				5,528,079	5,528,079
Common stock, conditional capital	38,453,593	38,453,593				2,444,364	2,444,364
Treasury stock, shares	274,184	274,184				0	0
Series A-1 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred stock, par value | (per share)		SFr 0.03					SFr 0.03					$ 1.28	SFr 1.14
Redeemable convertible preferred stock, shares authorized	440,001	440,001				440,001	440,001
Redeemable convertible preferred stock, shares issued	440,001	440,001				440,001	440,001					440,001	440,001
Redeemable convertible preferred stock, shares outstanding	440,001	440,001				440,001	440,001
Redeemable convertible preferred stock, aggregate liquidation preference | SFr		SFr 502					SFr 502
Series A-2 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred stock, par value | (per share)		SFr 0.03					SFr 0.03			$ 3.47	SFr 3.05
Redeemable convertible preferred stock, shares authorized	3,120,001	3,120,001				3,120,001	3,120,001
Redeemable convertible preferred stock, shares issued	3,120,001	3,120,001				3,120,001	3,120,001			3,120,001	3,120,001
Redeemable convertible preferred stock, shares outstanding	3,120,001	3,120,001				3,120,001	3,120,001
Redeemable convertible preferred stock, aggregate liquidation preference | SFr		SFr 9,512					SFr 9,512
Series A-3 Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred stock, par value | SFr / shares		SFr 0.03					SFr 0.03
Redeemable convertible preferred stock, shares authorized	10,758,006	10,758,006				10,758,006	10,758,006
Redeemable convertible preferred stock, shares issued	10,758,006	10,758,006				10,758,006	10,758,006		10,758,006
Redeemable convertible preferred stock, shares outstanding	10,758,006	10,758,006				10,758,006	10,758,006
Redeemable convertible preferred stock, aggregate liquidation preference | $	$ 45,700					$ 22,850
Series B Redeemable Convertible Preferred Shares [Member]
Redeemable convertible preferred stock, par value | SFr / shares		SFr 0.03					SFr 0.03
Redeemable convertible preferred stock, shares authorized	12,817,876	12,817,876				4,519,016	4,519,016
Redeemable convertible preferred stock, shares issued	12,817,876	12,817,876		2,834,252	5,464,608	4,519,016	4,519,016	4,519,016
Redeemable convertible preferred stock, shares outstanding	12,817,876	12,817,876				4,519,016	4,519,016
Redeemable convertible preferred stock, aggregate liquidation preference		SFr 28,000				$ 111,487	SFr 28,000

Consolidated Statement of Opera

Consolidated Statement of Operations and Comprehensive Loss - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Collaboration revenue	[1]	$ 1,549		$ 2,820
Operating expenses:
Research and development		12,052	$ 3,749	26,666	$ 6,399
General and administrative		4,107	2,453	18,974	7,164
Total operating expenses		16,159	6,202	45,640	13,563
Loss from operations		(14,610)	(6,202)	(42,820)	(13,563)
Other (expense) income:
Interest expense		(1)	(8)	(8,051)	(9)
Loss from equity method investment				(686)
Gain on extinguishment of convertible loan				11,482
Other (expense) income, net		(75)	9	(141)	(33)
Total other (expense) income, net		(76)	1	2,604	(42)
Net loss before (provision for) benefit from income taxes		(14,686)	(6,201)	(40,216)	(13,605)
(Provision for) benefit from income taxes		(8)	(153)	(84)	63
Net loss		(14,694)	(6,354)	(40,300)	(13,542)
Foreign currency translation adjustment		(1)	(4)	(18)	(2)
Comprehensive loss		(14,695)	(6,358)	(40,318)	(13,544)
Reconciliation of net loss to net loss attributable to common shareholders:
Net loss		(14,694)	(6,354)	(40,300)	(13,542)
Loss attributable to noncontrolling interest		14	1	24	309
Net loss attributable to common shareholders		$ (14,680)	$ (6,353)	$ (40,276)	$ (13,233)
Net loss per share attributable to common shareholders-basic and diluted		$ (2.77)	$ (1.15)	$ (7.43)	$ (2.72)
Weighted-average common shares outstanding used in net loss per share attributable to common shareholders-basic and diluted		5,292,348	5,528,079	5,422,617	4,872,048
[1]	Including the following amounts of revenue from a related party, see Note 13:

Consolidated Statement of Oper5

Consolidated Statement of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Income Statement [Abstract]
Revenue from related party	$ 385	$ 385

Consolidated Statements of Cash

Consolidated Statements of Cash Flows $ in Thousands, SFr in Millions	9 Months Ended
	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)
Operating activities
Net loss	$ (40,300)	$ (13,542)
Reconciliation of net loss to net cash used in operating activities:
Depreciation and amortization expense	513	68
Equity-based compensation expense	6,816	2,508
Non-cash interest expense	8,050
Loss from disposal of property and equipment	28
Unrealized foreign currency remeasurement loss	(7)	(99)
Gain on extinguishment of convertible loan	(11,482)
Loss from equity method investment	686
Changes in:
Restricted cash	(2,453)	(551)
Accounts receivable	(1,753)
Prepaid expenses and other assets	(694)	(513)
Accounts payable and accrued expenses	3,275	2,504
Deferred revenue	1,220
Deferred rent	196
Other liabilities, net	11	49
Net cash used in operating activities	(35,894)	(9,576)
Investing activities
Purchase of property and equipment	(2,788)	(651)
Proceeds from contribution of intellectual property to equity method investee	20,000
Cash investment in equity method investee	(100)
Net cash provided by (used in) investing activities	17,112	(651)
Financing activities
Proceeds from issuance of common shares	16
Issuance costs for preferred share financings	(1,810)	(370)
Payment of proposed public offering costs	(2,677)
Proceeds from issuance of convertible loans	35,000
Net cash provided by financing activities	91,454	58,251
Effect of exchange rate changes on cash	(20)	80
Increase in cash	72,652	48,104
Cash, beginning of period	155,961	945
Cash, end of period	228,613	49,049
Supplemental disclosure of non-cash investing and financing activities
Property and equipment purchases in accounts payable and accrued expenses	246	32
Conversion of Vertex and Bayer convertible loans and accrued interest	61,929
Noncash contribution of intellectual property to Casebia LLP	36,372
Costs for proposed public offering in accounts payable and accrued expenses	825
Series A-2 Redeemable Convertible Preferred Shares [Member]
Financing activities
Proceeds from issuance of preferred shares		5,293
Series A-3 Redeemable Convertible Preferred Shares [Member]
Financing activities
Proceeds from issuance of preferred shares	22,850	22,850
Series B Redeemable Convertible Preferred Shares [Member]
Financing activities
Proceeds from issuance of preferred shares	$ 38,075	$ 30,478

Organization and Operations

Organization and Operations	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Operations	1. Organization and Operations The Company CRISPR Therapeutics AG (“CRISPR” or the “Company”) was formed on October 28, 2013 in Basel, Switzerland. The Company was established to translate CRISPR/Cas9, a genome editing technology, into transformative gene-based medicines for the treatment of serious human diseases. The foundational intellectual property underlying the Company’s operations was licensed to the Company and its subsidiaries in April 2014. The Company devotes substantially all of its efforts to product research and development activities, initial market development and raising capital. The Company’s principal offices and operations are in Cambridge, Massachusetts. On January 23, 2014, the founders of the Company formed TRACR Hematology Limited (“TRACR”) in the United Kingdom, to further the development of the CRISPR/Cas9 technology into medicines for the treatment of blood-borne illnesses. As the Company was funding and managing TRACR’s operations in 2014, it has been consolidated by the Company from the date that the Company established a variable interest in TRACR in April 2014. In March 2015, the Company acquired 82.1% of the outstanding equity of TRACR in a share exchange transaction. On February 7, 2014, the Company formed a wholly-owned subsidiary in the United Kingdom, CRISPR Therapeutics Limited (“CRISPR Ltd.”), and on February 16, 2015, the Company formed a wholly-owned subsidiary in the United States, CRISPR Therapeutics, Inc. (“CRISPR Inc.”), as its principal research and development operation. In October 2016, the Company completed an initial public offering (“IPO”) whereby the Company sold 4,429,311 of its common shares (“Common Shares”), inclusive of 429,311 Common Shares sold by the Company pursuant to the partial exercise of an overallotment option granted to the underwriters in connection with the offering, at a price to the public of $14.00 per share. The shares began trading on the NASDAQ Global Market on October 19, 2016. The aggregate net proceeds received by the Company from the offering were $54.1 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company. Concurrent with the IPO, the Company issued and sold 2,500,000 Common Shares to Bayer Global Investments B.V., in a private placement, at the IPO price of $14.00 per share, for aggregate net proceeds of $35.0 million. Upon the closing of the IPO, all 27,135,884 of the Company’s outstanding preferred shares converted into Common Shares on a one-for-one basis and the Company issued 328,017 Common Shares to Dr. Emmanuelle Charpentier in exchange for the remaining non-controlling equity interest in TRACR pursuant to a call option agreement. Accordingly, in October 2016, TRACR became a wholly-owned subsidiary. See Note 4 for further details. The significant increase in shares outstanding in the fourth quarter of 2016 is expected to impact the year-over-year comparability of the Company’s net loss per share calculations for the next twelve months. The Company is subject to risks common to companies in the biotechnology industry, including but not limited to, risks of failure of preclinical studies and clinical trials, the need to obtain marketing approval for any drug product candidate that it may identify and develop, the need to successfully commercialize and gain market acceptance of its product candidates, dependence on key personnel, protection of proprietary technology, compliance with government regulations, development by competitors of technological innovations and ability to transition from pilot-scale manufacturing to large-scale production of products. The Company had an accumulated deficit of $74.2 million as of September 30, 2016 and has financed its operations to date from proceeds obtained from a series of preferred shares and convertible loan issuances and upfront fees received under its collaboration and joint venture arrangements. The Company will require substantial additional capital to fund its research and development and ongoing operating expenses. Liquidity The Company believes its cash of $228.6 million at September 30, 2016 and the net proceeds received from the IPO and concurrent private placement subsequent to September 30, 2016 will be sufficient to fund the Company’s current operating plan for at least the next 24 months. Thereafter, the Company will be required to obtain additional funding. There can be no assurance that the Company will be able to obtain additional debt or equity financing or generate product revenue or revenues from collaborative partners, on terms acceptable to the Company, on a timely basis or at all. The failure of the Company to obtain sufficient funds on acceptable terms when needed could have a material adverse effect on the Company’s business, results of operations, and financial condition.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Unaudited Interim Financial Information 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 (the “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 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 Prospectus that forms a part of the Company’s Registration Statement on Form S-1 (File No. 333-213577), which was filed with the SEC pursuant to Rule 424(b)(4) on October 19, 2016 (the “Prospectus”). 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 representation of the results for the reported interim periods. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in the Prospectus. There have been no material changes to the significant accounting policies during the period ended September 30, 2016. Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), and include the accounts of (i) the Company, (ii) its wholly-owned subsidiaries, CRISPR Ltd. and CRISPR Inc., and (iii) TRACR, a consolidated variable interest entity (“VIE”) and an 82.1% owned subsidiary as of December 31, 2015 and September 30, 2016. All intercompany accounts and transactions have been eliminated. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). The Company accounts for its 50% investment share of Casebia Therapeutics LLP under the equity method of accounting. See Note 8 for further details. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, equity-based compensation expense, revenue recognition, equity method investments, and reported amounts of expenses during the reported period. Significant estimates in these consolidated financial statements have been made in connection with the calculation of revenues, research and development expenses, equity-based compensation expense, fair value of Common Shares, fair value of intangible assets, and the provision for or benefit from income taxes. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. The Company utilizes significant estimates and assumptions in determining the fair value of its Common Shares. The Company utilized various valuation methodologies in accordance with the framework of the 2004 and 2013 American Institute of Certified Public Accountants Technical Practice Aids, Valuation of Privately- Held Company Equity Securities Issued as Compensation, to estimate the fair value of its Common Shares. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions affecting the biotechnology industry sector, the prices at which the Company sold preferred shares, the superior rights and preferences of securities senior to the Company’s Common Shares at the time, the likelihood of achieving a liquidity event, such as an initial public offering or a sale of the Company, and the Company’s discounted cash flows from forecasted operations. Significant changes to the key assumptions used in the valuations could result in different fair values of Common Shares at each valuation date and materially affect the financial statements. Amendment to Articles of Association In connection with preparing for its IPO, the Company’s board of directors and shareholders approved an amendment to the Company’s articles of association in July 2016. This amendment became effective upon registration in the Switzerland commercial register on July 27, 2016 and publication in the Swiss Official Gazette of Commerce on August 2, 2016. Pursuant to this amendment a 3 1 3 Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, 2014-09 Revenue Recognition 2014-09 In August 2014, the FASB issued ASU No. 2014-15, In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). The guidance addresses diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230, Statement of Cash Flows, and other Topics. The updated guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-15 on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”), which applies to all leases and will require lessees to record most leases on the balance sheet, but recognize expense in a manner similar to the current standard. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 and interim periods within those years, which is the year ended December 31, 2019 for the Company. Entities are required to use a modified retrospective approach of adoption for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited. The Company is evaluating the new guidance and the expected effect on its consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718) (“ASU 2016-09”). The guidance changes how companies account for certain aspects of equity-based payments to employees. Entities will be required to recognize income tax effects of awards in the income statement when the awards vest or are settled. The guidance also allows an employer to repurchase more of an employee’s shares than it can under current guidance for tax withholding purposes providing for withholding at the employee’s maximum rate as opposed to the minimum rate without triggering liability accounting and to make a policy election to account for forfeitures as they occur. The updated guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-09 on its consolidated financial position and results of operations. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). The guidance aims to reduce the diversity in practice and complexity associated with accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The new guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods, with early adoption permitted in the first interim period only. The amendments are to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements. For a discussion of other recent accounting pronouncements please refer to Note 2, “Summary of Significant Accounting Policies,” in the Prospectus. The Company did not adopt any new accounting pronouncements during the three months ended September 30, 2016.

Property and Equipment, net

Property and Equipment, net	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Property and Equipment, net	3. Property and Equipment, net Property and equipment, net, consists of the following (in thousands): As of September 30, As of December 31, Computer equipment and software $ 110 $ 118 Furniture, fixtures, and other 351 238 Laboratory equipment 2,758 861 Leasehold improvements 124 88 Construction work in process 1,063 95 4,406 1,400 Accumulated Depreciation (544 ) (72 ) Property and equipment, net $ 3,862 $ 1,328 Depreciation expense for the three and nine months ended September 30, 2016 and 2015, was $0.2 million, $27,000, $0.5 million and $27,000, respectively.

Variable Interest Entities

Variable Interest Entities	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Variable Interest Entities	4. Variable Interest Entities TRACR Hematology Limited On January 23, 2014, the founders of the Company formed TRACR in the United Kingdom, to further the development of the CRISPR/Cas9 technology into medicines for the treatment of blood-borne illnesses. On April 14, 2014, TRACR licensed certain foundational intellectual property rights under joint ownership from Dr. Charpentier to develop and commercialize products for the treatment or prevention of human diseases related to hemoglobinopathies. See Note 8 for further details of the technology license agreement with Dr. Charpentier. On April 14, 2014 the Company determined that it became the primary beneficiary of TRACR based on, among other factors, the Company’s power to direct the activities that significantly impacted the economic performance of TRACR and the Company’s financing of contractual obligations on behalf of TRACR, and the period in which the Company began to benefit from research and development of TRACR technology. Accordingly, the Company consolidated TRACR’s financial statements as a consolidated VIE beginning on April 14, 2014. The Company determined that TRACR met the definition of a business under the terms of ASC 805. As such, the Company accounted for the initial consolidation of TRACR as a business combination and measured the assets, liabilities and noncontrolling interests of TRACR in accordance with ASC 805 at the date the Company first became the primary beneficiary on April 14, 2014. The Company recorded $0.5 million of intangible assets on the Company’s consolidated balance sheet for TRACR’s intellectual property rights along with a related deferred tax liability of $0.1 million. TRACR did not have material operations prior to consolidation on April 14, 2014. On March 24, 2015, the Company acquired 4,600 ordinary shares of TRACR, representing 82.1% of the ordinary share capital, pursuant to a share exchange transaction with the shareholders of TRACR. In exchange for 4,600 ordinary shares of TRACR and the assignment of certain rights to subscribe ordinary shares of TRACR, the Company issued 852,846 Common Shares to two founders of TRACR, 656,031 restricted Common Shares to certain employees and non-employees, and 459,217 Common Shares to Fay Participation Corporation (“Fay Corp.”), an entity formed to hold Common Shares for future issuance to certain employees and non-employees. As of December 31, 2015 and September 30, 2016, the Company held 4,600 ordinary shares of TRACR, representing 82.1% of the ordinary share capital of TRACR. Upon the share exchange on March 24, 2015, the Company recorded an adjustment of $0.1 million to decrease the carrying amount of the noncontrolling interest in TRACR and reflect the Company’s increased ownership interest in TRACR’s net assets. This adjustment was recognized directly in equity through additional paid-in capital and is attributable to the controlling interest. Pursuant to the share exchange transaction on March 24, 2015, the Company also entered into a free standing call option agreement with Dr. Charpentier for 1,000 ordinary shares of TRACR, representing the remaining 17.9% of the ordinary share capital of TRACR. Under the terms of the call option agreement, the Company has the option to acquire the remaining 1,000 shares of TRACR held by Dr. Charpentier in exchange for 328,017 Common Shares of the Company. Upon the Company’s IPO in October 2016, the remaining 1,000 ordinary shares of TRACR held by Dr. Charpentier were automatically exchanged for 328,017 Common Shares of the Company and TRACR became a wholly-owned subsidiary of the Company.

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consist of the following (in thousands): As of September 30, 2016 As of December 31, 2015 Payroll and employee-related costs $ 1,987 $ 773 Research costs 1,752 910 Licensing fees 281 1,055 Professional fees 1,971 2,412 Intellectual property costs 4,232 2,592 Advance pay liability 2,007 — Other 172 688 Total $ 12,402 $ 8,430

Convertible Loans

Convertible Loans	9 Months Ended
	Sep. 30, 2016
Debt Disclosure [Abstract]
Convertible Loans	6. Convertible Loans 2015 Convertible Loan Agreement with Vertex and certain existing shareholders On October 26, 2015, the Company entered into a convertible loan agreement with Vertex Pharmaceuticals Incorporated (“Vertex”) and certain existing shareholders (the “Vertex Convertible Loan”) under which the Company could borrow up to $40.0 million. The Vertex Convertible Loan accrues interest at 2.5% per annum and had an initial maturity date of April 26, 2016 subject to acceleration upon the occurrence of certain conditions stated in the loan agreement (the “Maturity Date”). On various dates between November 23, 2015 and December 7, 2015, the Company borrowed aggregate net proceeds of $38.2 million. The Vertex Convertible Loan included various embedded conversion, redemption and other features, as further described below, none of which required separate accounting from the host instrument under ASC 815. On January 29, 2016, all of the outstanding principal plus accrued interest of $0.2 million under the Vertex Convertible Loan was automatically converted into 2,859,278 Series B Preferred Shares in connection with a qualified financing described below. The conversion terms, redemption terms, and other features of the Vertex Convertible Loan are included in the Prospectus. There were no changes to the conversion terms, redemption terms, and other features of the Vertex Convertible Loan during the nine months ended September 30, 2016. Convertible Loan with Bayer Global Investments B.V. Concurrent with the execution of the Bayer Joint Venture agreement, the Company also entered into a Convertible Loan Agreement (“Bayer Convertible Loan”) with Bayer Global Investments B.V., or Bayer BV for $35.0 million. The Bayer Convertible Loan accrued interest at 2.0% per annum and matured on January 29, 2016 (the “Maturity Date”). On January 29, 2016, the Company issued the Bayer Convertible Loan in exchange for aggregate net proceeds of $35.0 million. The Bayer Convertible Loan included various embedded conversion, redemption and other features, none of which required separate accounting from the host instrument under ASC 815. Conversion of Convertible Loans to Series B Preferred Shares On January 29, 2016, concurrent with the issuance of the Bayer Convertible Loan, all of the outstanding principal under the $35.0 million Bayer Convertible Loan automatically converted into 2,605,330 Series B Preferred Shares at $13.43 per share. The Company determined the fair value of the Bayer Convertible Loan to be $24.5 million based on the fair value of the underlying Series B Preferred Shares that were exchanged as part of the immediate conversion. As the Bayer Convertible Loan was executed in contemplation of the joint venture agreement with Bayer, the Company evaluated the Bayer Convertible Loan as part of one multiple-element arrangement and using a relative fair value allocation allocated $27.0 million of aggregate arrangement consideration to the Bayer Convertible Loan upon issuance (See Note 8). Upon conversion, the Company accreted the Bayer Convertible Loan to its face value of $35.0 million through a charge to interest expense of $8.0 million and converted the $35.0 million to Series B Preferred Shares under the conversion model. The receipt of $35.0 million in proceeds under the Bayer Convertible Loan in exchange for equity securities, combined with the $38.2 million in proceeds from Vertex Convertible Loan, triggered an automatic conversion provision of the Vertex Convertible Loan Agreement. Accordingly, on January 29, 2016, the Vertex Convertible Loan, including loans from existing shareholders, plus accrued interest also converted into 2,859,278 of Series B Preferred Shares at $13.43 per share. The Company determined the fair value of the Vertex Convertible Loan to be $26.9 million based on the fair value of the underlying Series B Preferred Shares that were exchanged as part of the conversion. Upon extinguishment, the Company recorded a gain on extinguishment of $11.5 million for the difference between the carrying value of the debt and the fair value of the Series B Preferred Shares issued to settle the debt under the general extinguishment model.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Operating Leases The Company had four non-cancellable operating leases for office, laboratory, and corporate housing spaces as of December 31, 2015. As of September 30, 2016, two of these have expired. The lease of the Company’s primary research facility space expires in February 2022, with one optional five-year extension period. Rental expense for the three months ended September 30, 2016 and 2015 was $0.5 million and $0.4 million, respectively, and for the nine months ended September 30, 2016 and 2015, was $1.4 million and $0.7 million, respectively. Future minimum payments required under the leases as of December 31, 2015, are as follows (in thousands): Year Ending December 31: Amount 2016 $ 1,291 2017 1,341 2018 1,381 2019 1,422 2020 1,465 Thereafter 1,700 Total minimum lease payments $ 8,600 During the nine months ended September 30, 2016, the Company entered into two sublease agreements for office and laboratory space, not included in the table above. The first of these began on April 1, 2016, and expires on January 31, 2017, and may continue on a tenancy-at-will basis with either party having the right to terminate with thirty days of notice. The Company’s contractual obligation related to lease payments over the term of this sublease is approximately $0.3 million. The second lease is expected to begin in December 2016, and expires ten years from the commencement date. The Company has the option to extend the term of the lease by five years. The Company’s contractual obligation related to lease payments over the term of the sublease is approximately $56.2 million. In April 2016, the Company entered a $2.5 million letter of credit to secure the Company’s obligations under a facility lease in Cambridge, Massachusetts. The letters of credit are secured by cash held in a restricted depository account. Letters of Credit As of December 31, 2015, and September 30, 2016, the Company had restricted cash of $0.7 million and $3.2 million, respectively, representing letters of credit securing the Company’s obligations under the facility leases in Cambridge, Massachusetts and certain credit card arrangements. The letters of credit are secured by cash held in a restricted depository account. Sponsored Research Agreements The Company has engaged several research institutions to identify new delivery strategies and applications of the CRISPR/Cas9 technology. As a result of these efforts, the Company has agreed to sponsor three research programs during 2016, with one of these programs continuing through 2018. In association with these agreements, the Company has committed to making payments for related research and development services of $1.2 million, $0.4 million, and $0.2 million in 2016, 2017, and 2018, respectively. License Agreement with Anagenesis Biotechnologies SAS On June 7, 2016, the Company entered into a license agreement with Anagenesis Biotechnologies SAS (“Anagenesis”) pursuant to which the Company received an exclusive worldwide license to Anagenesis’ proprietary technology for all human based muscle diseases. Pursuant to the license agreement, the Company made a one-time upfront payment of $0.5 million to Anagenesis and is required to pay Anagenesis up to $89.0 million upon the achievement of future clinical, regulatory and sales milestones for each of the first allogeneic and autologous licensed products developed pursuant to the license agreement, as well as low single digit royalty payments on future sales of commercialized product candidates. The Company recorded the $0.5 million payment during the nine months ended September 30, 2016 as research and development expense on the consolidated statement of operations. Licensing Agreements In April 2014, the Company and TRACR entered into technology license agreements with Dr. Charpentier pursuant to which the Company and TRACR licensed Dr. Charpentier’s interest to certain intellectual property rights jointly owned by Dr. Charpentier and others to develop and commercialize products for the treatment or prevention of human diseases. See Note 8 for further details. Litigation Under the license agreement with Dr. Charpentier, the Company licenses a U.S. patent application that is currently subject to interference proceedings declared by the Patent Trial and Appeal Board of the U.S. Patent and Trademark Office. If the Company’s licensed patent family does not prevail in these proceedings, claims could be asserted against the Company during development or commercialization of a product that relies on this technology. Defense of any such claims would involve substantial litigation expense, and any successful claim of infringement against the Company could require the Company to pay substantial damages. Shareholder Settlement For the year ended December, 31, 2015, the Company has determined that it is considered a passive foreign investment company (“PFIC”). Under the terms of a shareholder agreement existing prior to the IPO, if a U.S. common shareholder elected to file a Qualified Electing Fund (“QEF”) and notified the Company of this election, the Company was required to make advance payments to the shareholder related to their individual 2015 tax liability. Under the shareholder agreement, the Company was obligated to notify investors 30 days after December 31, 2015 that it was considered a PFIC; however, the Company did not finalize the determination of its PFIC status until after this date. If timely notification had been given to the U.S. common shareholders and all U.S. common shareholders notified the Company that a QEF election was made, the Company estimates that it may have been required to make advance payments of up to $2.6 million for the tax year ended December 31, 2015. As no QEF elections had been made prior to the date the Company issued its December 31, 2015 financial statements, the Company has not paid or accrued any amounts as of December 31, 2015. In September 2016, the Company formally offered an aggregate settlement up to $2.0 million to certain U.S common shareholders in order to release the Company from any and all obligations or claims concerning and/or arising out of the Company’s status as a PFIC or a Controlled Foreign Corporation (a “CFC”) for any taxable year from 2013 through 2015, including for potential lack of timely notification of the Company’s PFIC status for the year ended December 31, 2015. This amount represented the Company’s best estimate of its probable liability related to this matter and was recorded in accrued expenses in its consolidated balance sheet as of September 30, 2016. The Company recorded charges of $0.1 million and $2.0 million in general and administrative expenses in the consolidated statement of operations for the three months and nine months ended September 30, 2016, respectively. Following the formal settlement offer in September 2016, this settlement has been accepted by substantially all of the U.S. common shareholders representing $1.8 million of the aggregate settlement of $2.0 million. In October 2016, the Company made payments of $1.8 million under the terms of the accepted settlements. If the settlement is not accepted by the remaining U.S. common shareholder, the Company believes the maximum obligation to make advance payments under the shareholder agreement is $0.2 million. The obligation to make advance payments under the shareholder agreement for tax years subsequent to 2015 terminated upon the closing of the IPO.

Significant Contracts

Significant Contracts	9 Months Ended
	Sep. 30, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Significant Contracts	8. Significant Contracts Intellectual Property Agreements CRISPR Therapeutics AG—Charpentier License Agreement In April 2014, the Company entered into a technology license agreement with Dr. Charpentier pursuant to which the Company licensed certain intellectual property rights under joint ownership from Dr. Charpentier to develop and commercialize products for the treatment or prevention of human diseases other than hemoglobinopathies (“CRISPR—Charpentier License Agreement”). In consideration for the granting of the license, the Company paid Dr. Charpentier an upfront fee of CHF 0.1 million ($0.1 million), and agreed to pay an immaterial annual license maintenance fee if Dr. Charpentier is not otherwise engaged in a service arrangement with the Company. During the three and nine months ended September 30, 2015 and 2016, Dr. Charpentier has been in a consulting arrangement with the Company, as such, no annual payments have been made under this provision. Dr. Charpentier is entitled to receive nominal clinical milestone payments. The Company is also obligated to pay Dr. Charpentier a low single digit percentage of sublicensing payments received under any sublicense agreement with a third party. In addition, the Company is also obligated to pay to Dr. Charpentier a low single-digit percentage royalty based on annual net sales of licensed products and licensed services by the Company and its affiliates and sublicensees. During the three and nine months ended September 30, 2016 and 2015, the Company recorded $0, $0, $0.3 million, and $0, respectively, of sublicensing fees due to Dr. Charpentier in research and development expense under the terms of the CRISPR—Charpentier License Agreement that was triggered by the execution of the Vertex collaboration agreement and the Bayer joint venture agreement. TRACR Hematology Limited—Charpentier License Agreement In April 2014, TRACR entered into a technology license agreement (“TRACR—Charpentier License Agreement”) with Dr. Charpentier pursuant to which TRACR licensed certain intellectual property rights under joint ownership from Dr. Charpentier to develop and commercialize products for the treatment or prevention of human diseases related to hemoglobinopathies. In consideration for the granting of the license, Dr. Charpentier is entitled to receive nominal clinical milestone payments. TRACR is also obligated to pay Dr. Charpentier a low single digit percentage of sublicensing payments received under any sublicense agreement with a third party. In addition, TRACR is obligated to pay to Dr. Charpentier low single digit percentage royalties based on annual net sales of licensed products and licensed services by the Company and its affiliates and sublicensees. During the three months and nine months ended September 30, 2015 and 2016, no amounts were paid under the terms of the TRACR—Charpentier License Agreement. Patent Assignment Agreement In November 2014, the Company entered into a patent assignment agreement (“Patent Assignment Agreement”) with Dr. Charpentier, Dr. Ines Fonfara, and the University of Vienna (collectively, the “Assignors”), pursuant to which the Company was assigned all rights, title and interest in and to certain patent rights claimed in the U.S. Patent Application No.61/905,835. In consideration for the assignment of such rights, the Assignors are entitled to receive clinical milestone payments totaling up to €0.3 million (approximately $0.4 million) in the aggregate for the first human therapeutic product. The Company is also obligated to pay to the Assignors low single digit royalties based on annual net sales of licensed products and licensed services by the Company and its affiliates and sublicensees. During the three months and nine months ended September 30, 2016 and 2015, the Company did not record any sublicensing fees due to the Assignors in research and development expense under the terms of the Patent Assignment Agreement that was triggered by the execution of the Vertex collaboration agreement and the Bayer joint venture agreement. Collaboration Agreement with Vertex Pharmaceuticals, Incorporated Summary of Agreement On October 26, 2015, the Company entered into a strategic collaboration, option, and license agreement (“Collaboration Agreement”) with Vertex, focused on the use of CRISPR’s gene editing technology, known as CRISPR/Cas9, to discover and develop potential new treatments aimed at the underlying genetic causes of human disease. The collaboration will evaluate the use of CRISPR-Cas9 across multiple diseases where targets have been validated through human genetics. Vertex and CRISPR will focus their initial gene editing research on discovering treatments to address the mutations and genes known to cause and contribute to sickle cell disease, beta-thalessemia and cystic fibrosis. Vertex and CRISPR will also evaluate a specified number of other genetic targets as part of the collaboration. For up to six targets, Vertex has an exclusive option to obtain: (1) an exclusive license to commercialize CRISPR technology (“Exclusive License”) or (2) a co-exclusive license with respect to hemoglobinopathy and beta-globin targets (“Co-exclusive License”). The collaborative program of research to be undertaken by the parties pursuant to the Collaboration Agreement will be conducted in accordance with a mutually agreed upon research plan which outlines each party’s research and development responsibilities across the three research areas. The Company’s research and development responsibilities under the research plan (“R&D Services”) are related to generating genome editing reagents that modify gene targets selected by Vertex. Except with respect to the Company’s obligations under the mutually agreed upon research plan, Vertex has sole responsibility, at its own costs, for the worldwide research, development, manufacturing and commercialization of products resulting from the exclusive licenses obtained. The research collaboration will end on the earlier of the date on which Vertex has exercised six options to obtain exclusive/co-exclusive licenses with respect to a collaboration target, or the fourth anniversary of the effective date of the agreement. The research term may be extended as mutually agreed by the parties up to nine additional months to complete any research activities under the approved research plan that are incomplete on the fourth anniversary of the effective date. The Collaboration Agreement will be managed on an overall basis by a project leader from each of the Company and Vertex. In addition, the activities under the collaboration agreement during the research term will be governed by a joint research committee (“JRC”) formed by an equal number of representatives from the Company and Vertex. Decisions by the JRC will be made by consensus of the group, however, Vertex will have final decision-making authority in the event of disagreement, provided it is in good faith and not contrary to any explicit clause of the agreement. In connection with the agreement, Vertex made a nonrefundable upfront payment of $75.0 million. In addition, Vertex will fund all of the discovery activities conducted pursuant to the agreement. For potential hemoglobinopathy treatments, including treatments for sickle cell disease, the Company and Vertex will share equally all research and development costs and worldwide revenues. For other targets that Vertex elects to license, Vertex would lead all development and global commercialization activities. For each of up to six targets that Vertex elects to license, other than hemoglobinopathy and beta-globin targets, the Company has the potential to receive up to $420.0 million in development, regulatory and commercial milestones and royalties on net product sale. Vertex is entitled to terminate the Collaboration Agreement as a whole, or terminate the Collaboration Agreement in part with respect to a particular collaboration program, for convenience by providing the Company 90 days’ written notice of such termination; provided, however, that if any termination applies to a product for which Vertex has received marketing approval, Vertex will provide CRISPR no less than 270 days’ notice of such termination. If Vertex is in material breach of this Collaboration Agreement, the Company has the right to terminate the Collaboration Agreement in full at its discretion 90 days after delivery of written notice to Vertex. The Company evaluated the Collaboration Agreement in accordance with the provisions of ASC 605-25. The Company’s arrangement with Vertex contains the following initial deliverables: (i) a non-exclusive research license; (ii) the option to obtain an exclusive license for up to six Collaboration Targets; (iii) the option to obtain a co-exclusive license for hemoglobinopathy or beta-globin targets (which would be included within the maximum number of the aforementioned six collaboration targets); (iv) R&D Services; and (v) JRC participation. Management considered whether any of these deliverables could be considered separate units of accounting. Regarding the non-exclusive research license, the Company concluded that it does not have stand-alone value separate from the option to exercise the exclusive or co-exclusive license since Vertex would not benefit from acquiring a research license without the ability to obtain the license to commercialize the results of that research. As a result, the Company concluded that the research license should be combined with those options. Regarding the R&D Services, the Company concluded that there are other vendors in the market that could perform the related services. As such the Company concluded the R&D Services represent a separate unit of accounting. Regarding the JRC obligations, the Company concluded that the JRC obligations deliverable has standalone value from the option to license because the services could be performed by an outside party. As such the Company concluded the JRC obligations represent a separate unit of accounting. As a result, management concluded that there are four units of accounting at the inception of the agreement: (i) a combined unit of accounting representing the non-exclusive research license, and the option for up to six exclusive licenses to develop and commercialize the collaboration targets as these options do not have stand- alone value; (ii) a combined unit of accounting representing the non-exclusive research license, and the option for a co-exclusive license (subject to the aforementioned six license limit) to develop and commercialize the hemoglobinopathy or beta-globin targets as these options do not have stand-alone value; (iii) the performance of R&D Services; and (iv) the participation in the JRC. The Company has determined that neither VSOE of selling price nor TPE of selling price is available for any of the units of accounting identified at inception of the arrangement. Accordingly, the selling price of each unit of accounting was determined based on the Company’s BESP. The Company developed the BESP for all of the units of accounting included in the collaboration agreement with the objective of determining the price at which it would sell such an item if it were to be sold regularly on a standalone basis. The Company developed the BESP for the R&D Services and the JRC participation primarily based on the nature of the services to be performed and estimates of the associated effort and cost of the services, adjusted for a reasonable profit margin that would be expected to be realized under similar contracts. The Company’s BESP for the R&D Services was $26.7 million. The Company’s BESP for the JRC participation services was de minimis based on an estimate of time spent on preparation, participation, review and travel for the meetings. The Company’s BESP for each combined unit of the non-exclusive research license and the option for an exclusive license to develop and commercialize a single collaboration target is $37.7 million. As the Company expects Vertex to exercise five of these options, the total BESP is $188.5 million. BESP for this item was determined based on probability and present value adjusted cash flows from the royalties and milestones outlined in the Collaboration Agreement. BESP reflects the level of risk and expected probability of success inherent in the nature of the associated research area. The Company’s BESP for a non-exclusive research license and the option for a co-exclusive license to develop and commercialize a single hemoglobinopathy or beta-globin collaboration target is $12.5 million. As the Company expects Vertex to exercise one of these options, the total BESP is $12.5 million. BESP for this item was determined based on probability and present value adjusted cash flows from the equal sharing of project worldwide net profit or net loss. BESP reflects the level of risk and expected probability of success inherent in the nature of the associated research area. Allocable arrangement consideration at inception is comprised of: (i) the up-front payment of $75.0 million, (ii) the estimated R&D services of $26.7 million and (iii) payments related to the estimated exercise of options on future exclusive licenses for five targets of $50.0 million. The aggregate allocable arrangement consideration of $151.7 million was allocated among the separate units of accounting using the relative selling price method as follows: (i) R&D Services: $17.8 million, (ii) non-exclusive research license, and the option for an Exclusive License to develop and commercialize the five collaboration targets: $125.5 million, (iii) non-exclusive research license, and the option for one Co-exclusive License to develop and commercialize one hematology target: $8.4 million. The amount allocated to R&D Services will be recognized as the R&D Services are performed. The Company will recognize as license revenue an equal amount of the total arrangement consideration allocated to the exclusive licenses as each individual license is delivered to Vertex upon Vertex’s exercise of its options to such licenses. The Company will recognize $8.4 million as license revenue when the Co-exclusive License is delivered to Vertex upon Vertex’s exercise of its options to such license. The Company has evaluated all of the milestones that may be received in connection with the Collaboration Agreement. In evaluating if a milestone is substantive, the Company assesses whether: (i) the consideration is commensurate with either the Company’s performance to achieve the milestone or the enhancement of the value of the delivered item(s) as a result of a specific outcome resulting from the Company’s performance to achieve the milestone, (ii) the consideration relates solely to past performance, and (iii) the consideration is reasonable relative to all of the deliverables and payment terms within the arrangement. The Company notes that the $10.0 million due upon the exercise of each option for an Exclusive License was determined to be part of the fixed and determinable consideration allocable at contract inception and is not subject to milestone method accounting. The first potential milestone the Company will be entitled to receive is the $10.0 million milestone due upon the filing of an Investigational New Drug Application (“IND”) for a selected Exclusive License. As the first developmental milestone of the agreement relates to the filing of an IND, the Company has considered it to be substantive. Accordingly, such amounts will be recognized as revenue in full in the period in which the associated milestone is achieved, assuming all other revenue recognition criteria are met. There are no other substantive milestones. As such the total amount of substantive milestones subject to milestone method accounting treatment is $10.0 million for each selected Exclusive License. The remaining milestones are predominately related to the development and commercialization of a product resulting from the arrangement and are payable with respect to each selected Exclusive License. Each milestone is payable only once per collaboration target, regardless of the number of products directed to such collaboration target that achieve the relevant milestone event. There are nine remaining clinical development and regulatory approval milestones which may trigger proceeds of up to $90.0 million and $235.0 million, respectively, for each selected Exclusive License, and two commercial milestones which may trigger proceeds of up to $75.0 million for each selected Exclusive License (which, when combined with the $10.0 million due upon exercise of the exclusive option and the $10.0 million development milestone associated with an IND, total $420.0 million for each selected Exclusive License), as follows: Developmental Milestone Events 1. Initiation of the first Clinical Trial of a Product 2. Establishment of POC for a Product 3. Initiation of the first Phase 3 Clinical Trial of a Product 4. Acceptance of Approval Application by the FDA for a Product 5. Acceptance of Approval Application by the EMA for a Product 6. Acceptance of Approval Application by a Regulatory Authority in Japan for a Product 7. Marketing Approval in the US for a Product 8. Marketing Approval in the EU for a Product 9. Marketing Approval in Japan for a Product Commercial Milestone Events 1. Annual Net Sales for Products with respect to a Collaboration Target exceed $500 million 2. Annual Net Sales for Products with respect to a Collaboration Target exceed $1,000 million After Vertex has exercised an Exclusive License option, Vertex will be solely responsible for all research, development, manufacturing, and commercialization of licensed agents and products for the relevant target. As the Company’s involvement in this process is limited to observer status, management determined that milestones are not considered substantive because they do not relate solely to the past performance of the Company. Upon the achievement of a milestone, management will evaluate whether the triggering event occurs during or after the research term. If the triggering event occurs during the research term, management has elected to treat the milestone similar to an up-front payment. In these cases, if and when any of these milestones are received, the amount will be included in the overall arrangement consideration and allocated to the remaining identified deliverables. To the extent all deliverables have been satisfied, any additional consideration allocated to them could be immediately recognized. If the triggering event occurs after the research term, the Company will recognize the associated revenue in the period in which the event occurs. The Company will recognize royalty revenue in the period of sale of the related product(s), based on the underlying contract terms, provided that the reported sales are reliably measurable and the Company has no remaining performance obligations, assuming all other revenue recognition criteria are met. During the three and nine months ended September 30, 2016 and 2015, the Company recognized $1.2 million, $0, $2.4 million, and $0 of revenue with respect to the collaboration with Vertex. Research and development expense incurred by the Company in relation to its performance under the Collaboration Agreement for the three and nine months ended September 30, 2016 and 2015, was $1.7 million, $0, $4.5 million, and $0, respectively. As of September 30, 2016, and December 31, 2015, there is $76.3 million and $75.1 million of non-current deferred revenue related to the Company’s collaboration with Vertex. Joint Venture with Bayer Healthcare LLC On December 19, 2015, the Company entered into an agreement to establish a joint venture (“Bayer Joint Venture”) with Bayer to research the development of new therapeutics to cure blood disorders, blindness, and congenital heart disease. On February 12, 2016, the Company and Bayer completed the formation of the joint venture entity, Casebia Therapeutics LLP (“Casebia”), a limited liability partnership formed in the United Kingdom. Bayer and the Company each received a 50% equity interest in the entity in exchange for their contributions to the entity. The Company contributed $0.1 million in cash and licensed its proprietary CRISPR/Cas9 gene editing technology and intellectual property for selected disease indications. Bayer contributed its protein engineering expertise and relevant disease know-how. Bayer will provide up to $300.0 million in research and development funding to Casebia over the first five years, subject to certain conditions, of which the first $45.0 million was contributed upon formation in the first quarter of 2016. Under the joint venture agreement, the Company has no obligation to provide any additional funding and the Company’s ownership interest will not be diluted from future contributions from Bayer. The activities of Casebia are controlled by a management board under the joint control of the Company and Bayer. As Casebia is jointly controlled by the Company and Bayer, the Company accounts for its 50% interest using the equity method of accounting. Under the agreement, Casebia will pay the Company up to $35.0 million in exchange for a worldwide, exclusive license to commercialize the Company’s CRISPR/Cas9 technology specifically for the indications designated by Casebia. In March 2016, the Company received a non-refundable up-front payment of $20.0 million as a technology access fee. The remaining $15.0 million will be paid upon the delivery of the consent necessary from the patent holders of the Company’s intellectual property. There are no milestone, royalties or other payments due to the Company under this aspect of the agreement. The Company determined that the contribution of the CRISPR/Cas9 technology by license to Casebia did not meet the definition of a business under ASC 805. The Company will also provide to Casebia compensated research and development services through a separate agreement. Revenue related to research and development services rendered by the Company was $0.5 million, $0, $0.5 million, and $0 during the three months ended September 30, 2016 and 2015, and the nine months ended September 30, 2016 and 2015, respectively. Concurrent with the execution of the Bayer Joint Venture agreement, the Company also entered into the Bayer Convertible Loan for $35.0 million. As the Bayer Joint Venture (including the CRISPR/Cas9 technology license and the research and development services) and the Bayer Convertible Loan were executed at the same time, the Company determined that they should be evaluated as one multiple-element arrangement. Additionally, the Company also determined that ASC 845, Nonmonetary Transactions The Company allocated the fair value of the consideration received using a relative fair value allocation. The allocable arrangement consideration included (i) the total cash payment by Casebia for the technology access fee, net of the Company’s $0.1 million contribution, of $34.9 million, (ii) the fair value of the equity interest in the Joint Venture of $36.4 million, (iii) the $35.0 million received from the issuance of the Convertible Debt, and (iv) $6.3 million of estimated cash consideration to be received under the research and development service arrangement, accumulating to $112.6 million. The Company identified the following elements under the transaction: (i) Combined element of an exclusive, worldwide, royalty free, license to the CRISPR/Cas9 technology specifically for the indications designated by Casebia, and delivery of the consents of the assignors of the underlying patents to the technology to develop, manufacture, and commercialize licensed products under that license, (ii) Research and development services, and (iii) The issuance of the Bayer Convertible Loan. The Company determined the fair value of the license was $71.4 million based on the consideration paid and the fair value of the 50% interest in Casebia, which was determined utilizing discounted cash flows based on reasonable estimates and assumptions of cash flows expected from Casebia. The fair value of the separate research and development services was determined to be $6.3 million. The fair value of the Bayer Convertible Loan was determined to be $24.5 million, based on the fair value of the underlying preferred shares that were exchanged as part of the immediate conversion. Using a relative fair value allocation, the Company allocated the aggregate arrangement consideration paid as follows: (i) $63.6 million was allocated to the license and patent holder consent combined element, (ii) $0.6 million was allocated to the future research and development services, and (iii) $27.0 million was allocated to the Bayer Convertible Loan. The difference between combined above amounts of $91.2 million and the total allocable arrangement consideration of $112.6 million is due to allocable arrangement consideration which is not yet due associated with the $6.3 million of estimated cash consideration to be received under the research and development service arrangement and the remaining $15.0 million of the license fee which will be paid upon the delivery of the consent necessary from the patent holders of the Company’s intellectual property. Upon the delivery of the patent holders’ consent, the combined amount attributed to the license element will be recognized as other income. Until such time, it will be reflected as a Deferred Gain on the consolidated balance sheet. The Company determined that this amount did not meet the definition of revenue because the licensing of its technology in connection with the formation of a joint venture is not part of the Company’s major ongoing or central operations. The amount attributed to future research and development services is recorded as deferred revenue as of September 30, 2016, net of the $35,000 recognized for services performed to date, and will be recognized in future periods as the research and development services are provided. As the amount allocated to the Bayer Convertible Loan represents a $8.0 million discount to its $35 million face value, the Company recognized interest expense during the nine months ended September 30, 2016 equal to the discount. The Convertible Loan automatically converted into Series B preferred shares on its January 29, 2016 maturity date. As of September 30, 2016, the Company has recorded an equity method investment of $35.7 million equal to the fair value of the Company’s interest in Casebia of $36.4 million (which was included in the allocable arrangement consideration described above) less equity method losses of $0.7 million for the nine months ended September 30, 2016. Total operating expenses, and net loss of Casebia for the three and nine months ended September 30, 2016 was $3.0 million and $77.1 million, which included research and development expenses equal to $71.4 million for the fair value of the CRISPR license acquired. During the three and nine months ended September 30, 2016, the Company recorded equity method losses of $0 and $0.7 million. The Company has not recorded unrealized losses of $35.7 million from its accounting of the equity in the losses of Casebia until such time that the deferred gain allocated to the license and patent holder consent combined element is realized. Subscription Agreement with Bayer Global Investments B.V. On December 19, 2015, the Company entered into a subscription agreement, (“Subscription Agreement”), with Bayer Global Investments B.V., (“Bayer BV”). Pursuant to the Subscription Agreement, Bayer BV was given the option, at its election, to purchase $35.0 million of the Company’s Common Shares in a private placement concurrent with the Company’s IPO at a per share price equal to the public offering price. In October 2016, concurrent with the IPO, the Company issued and sold 2,500,000 Common Shares to Bayer BV, at the IPO price of $14.00 per share (the “Concurrent Private Placement”) resulting in aggregate net proceeds of $35.0 million in accordance with the terms of the Company’s subscription agreement with Bayer BV.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Shares	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Redeemable Convertible Preferred Shares	9. Redeemable Convertible Preferred Shares The Company’s redeemable convertible preferred shares (collectively, the “Preferred Shares”) have been classified as temporary or mezzanine equity on the accompanying consolidated balance sheets in accordance with authoritative guidance for the classification and measurement of redeemable securities as the Preferred Shares were contingently redeemable at the option of the holders. The redemption terms, conversion terms, rights, preferences, and privileges of the Preferred Shares are included in the Prospectus. There were no changes to the redemption terms, conversion terms, rights, preferences, and privileges of the Preferred Shares during the nine months ended September 30, 2016. In October 2013, the Company issued 440,001 Series A-1 Preferred Shares for CHF 1.14 ($1.28) per share, resulting in gross proceeds of CHF 0.5 million ($0.6 million). In April 2014, the Company issued 3,120,001 Series A-2 Preferred Shares in exchange for CHF 3.05 ($3.47) per share of such amount CHF 1.45 ($1.65) per share was received upon issuance resulting in gross proceeds of CHF 4.5 million ($5.1 million) and the balance of CHF 1.60 ($1.82) per share was called in February 2015 by the Board of Directors of the Company resulting in additional gross proceeds of CHF 5.0 million ($5.3 million). In April 2015, the Company issued 10,758,006 Series A-3 Preferred Shares in exchange for $4.24 per share whereby $2.12 per share was received upon issuance, resulting in gross proceeds of $22.8 million and the balance of $2.12 per share was due upon meeting certain milestones. As of December 31, 2015, none of the milestones had occurred and the Company had an outstanding subscription receivable of $22.8 million related to the Series A-3 Preferred Shares. The balance of the Series A-3 Preferred Share subscription receivable of $2.12 per share was called on May 5, 2016 by the Board of Directors and gross proceeds of $22.8 million were received by May 27, 2016. In May 2015, the Company issued 4,519,016 Series B Preferred Shares in exchange for CHF 6.20 ($6.74) per share resulting in gross proceeds of CHF 28.0 million ($30.5 million). In January 2016, the Company issued 5,464,608 Series B Preferred Shares upon conversion of $38.4 million of Vertex Convertible Loans plus accrued interest and $35.0 million of Bayer Convertible Loans at a conversion price of $13.43 per share. In June 2016, the Company issued 2,834,252 Series B Preferred Shares in exchange for $13.43 per share resulting in gross proceeds of $38.1 million. In October 2016, upon the closing of the IPO, all 27,135,884 of the Company’s outstanding Preferred Shares converted into Common Shares on a one-for-one basis.

Share Capital

Share Capital	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Share Capital	10. Share Capital As of December 31, 2015 and September 30, 2016, the Company had 5,528,079 and 5,662,126 registered Common Shares, respectively, and 18,837,024 and 27,135,884 registered Preferred Shares, respectively, outstanding with a par value of CHF 0.03 per share in share capital. Of the 5,662,126 Common Shares registered at September 30, 2016, 97,744 of these relate to an unvested restricted share award, and are not considered outstanding. Outstanding share capital also includes 8,747 vested restricted shares and 8,900 exercised stock options, which are authorized in conditional capital but not yet registered in the Swiss Commercial Register as issued share capital. The voting, dividend and liquidation rights of the holders of Common Shares are subject to and qualified by the rights, powers and preferences of the holders of Preferred Shares and are included in the Prospectus. There were no changes to the voting, dividend and liquidation rights of the holders of Common Shares during the nine months ended September 30, 2016. Conditional Capital Since inception, the Company has created conditional capital for the establishment of its 2015 option and grant plan (the “2015 Plan”), shares issuable under the terms of the call option agreement with Dr. Charpentier, and Preferred Shares issuable under the terms of the convertible loan financings. In July 2016, the Company created additional conditional capital which would enable an increase in its share capital of up to 34,329,942 Common Shares, with a par value of CHF 0.03 per share, to be used in the IPO, the concurrent private placement, bonds and similar debt instruments post-IPO, and employee benefit plans. Conditional Capital Reserved for Future Issuance The Company had the following conditional capital reserved for future issuance: Type of Share Capital Conditional Capital As of September 30, As of December 31, Common Shares Charpentier Call Option 328,017 328,017 Common Shares Vested unissued restricted share awards under 2015 Plan 8,747 — Common Shares Unvested unissued restricted share awards under 2015 Plan 166,667 142,794 Common Shares Exercised options under the 2015 Plan 8,900 — Common Shares Outstanding stock options awards under 2015 Plan 3,558,998 1,939,986 Common Shares Reserved for future issuance under the 2015 Plan 52,322 33,567 Common Shares Shares available for IPO 16,399,005 — Common Shares Shares available for concurrent private placement 2,605,330 — Common Shares Shares available for bonds and similar debt instruments 4,919,700 — Common Shares Shares available for employee benefit plans 10,405,907 — Total 38,453,593 2,444,364

Equity-based Compensation

Equity-based Compensation	9 Months Ended
	Sep. 30, 2016
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity-based Compensation	11. Equity-based Compensation 2015 Option and Grant Plan In April 2015, the shareholders approved the 2015 Plan. The 2015 Plan provides for the issuance of equity awards in the form of restricted shares, options to purchase Common Shares which may constitute incentive stock options (“ISOs”) or non-statutory stock options (“NSOs”), unrestricted stock unit grants, and qualified performance-based awards to eligible employees, officers, directors, consultants, and other key personnel. Terms of the equity awards, including vesting requirements, are determined by the Board, subject to the provisions of the Plan. Options granted by the Company typically vest over four years and have a contractual life of ten years. As of December 31, 2015, no options were exercised and there were 1,939,986 options outstanding and 142,794 restricted shares granted under the 2015 Plan. As of September 30, 2016, options to purchase 8,900 Common Shares were exercised and there were 3,558,998 options outstanding and 142,794 restricted shares granted under the 2015 Plan. As of December 31, 2015 and September 30, 2016, the Company has 33,567 and 218,989 Common Shares, respectively, reserved for future grant under the 2015 Plan. Prior to July 2016, the Company has historically denominated equity awards in Swiss Francs and converted such awards to U.S. dollars using the applicable exchange rate on the date of grant for financial reporting purposes. On July 27, 2016, the Company revised the 2015 plan documents to provide that all grants would be denominated in U.S. dollars in preparation for the Company’s IPO. Accordingly, the Company converted all exercise prices denominated in Swiss Francs to U.S. dollars using the exchange rate on July 27, 2016. The modification did not result in incremental value to the option holders and thus no incremental stock based compensation expense was recorded during the nine months ended September 30, 2016 in connection with the modification. Prior to the adoption of the 2015 Plan, certain employees and non-employees were granted restricted Common Shares directly from the Company and from a pool of unrestricted Common Shares held by the founders and Fay Corp. Such shares are treated as issued and outstanding Common Shares by the Company in all periods presented. In August 2016, the Company granted 206,929 options to purchase Common Shares from Treasury Shares held by the Company. Terms of the equity awards, including vesting requirements, are determined by the Board. Options granted by the Company vest over four years and have a contractual life of ten years. Equity-based Compensation Expense Total equity-based compensation expense is recognized for stock options and restricted shares granted to employees and non-employees and has been reported in the Company’s consolidated statements of operations as follows (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Research and development $ 1,343 $ 439 $ 2,834 $ 1,118 General and administrative 950 590 3,982 1,390 Total $ 2,293 $ 1,029 $ 6,816 $ 2,508 The following table summarizes stock option activity under the 2015 Plan and from Treasury Shares for employees and non-employees (intrinsic value in thousands): Stock Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2015 1,939,986 $ 2.31 9.7 $ 6,688 Granted 1,847,506 $ 10.95 Exercised (8,900 ) $ 1.97 Cancelled or forfeited (12,665 ) $ 4.96 Outstanding at September 30, 2016 3,765,927 $ 6.53 9.2 $ 22,764 Exercisable at September 30, 2016 695,053 $ 2.13 9.0 $ 7,255 Vested or expected to vest at September 30, 2016 (1) 3,112,563 $ 5.74 9.2 $ 21,288 (1) Represents the number of vested options at September 30, 2016 plus the number of unvested options expected to vest based on the unvested options outstanding at September 30, 2016. During the nine months ended September 30, 2016 and 2015, the Company granted stock options to purchase 1,847,506 and 1,703,403 Common Shares with a weighted-average grant date fair value of $7.68 and $3.01 per share, respectively. As of December 31, 2015 and September 30, 2016, the total unrecognized compensation cost related to employee, non-vested stock options granted was $4.2 million and $11.7 million, respectively. As of December 31, 2015 and September 30, 2016, the total unrecognized compensation cost related to non-employee, non-vested stock options granted was $0.1 million and $0.3 million, respectively. As of December 31, 2015 and September 30, 2016, the Company expects to recognize total unrecognized compensation cost over a remaining weighted-average period of 3.3 years and 3.3 years, respectively. During the nine months ended September 30, 2016 and 2015, the Company granted options to purchase 429,998 and 261,389 Common Shares, respectively, subject to service and performance-based vesting conditions. The Company is recognizing compensation expense ratably over the required service period based on its estimate of the number of shares that will vest. If there is a change in the estimate of the number of shares that are probable of vesting, the Company will cumulatively adjust compensation expense in the period that the change in estimate is made. The Company estimates the fair value of each employee and non-employee stock award on the grant date using the Black-Scholes option-pricing model based on the following range of assumptions regarding the fair value of the underlying Common Shares on each measurement date: Three Months Ended Nine Months Ended September 30, 2016 2015 2016 2015 Employees: Weighted average expected volatility 84.6 % 76.0 % 81.8 % 76.1 % Expected term (in years) 6.0 6.0 6.0 6.0 Risk free interest rate 1.1 - 1.3 % 1.7 % 1.1 - 1.5 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % Non employees: Weighted average expected volatility 93.6 % 84.0 % 93.6 % 84.0 % Expected term (in years) 10.0 10.0 10.0 10.0 Risk free interest rate 1.6 % 2.2 % 1.6 % 2.2 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % The Company also grants share based payment awards in the form of founder shares transferred to employees (Founder Shares) and restricted shares subject to service based vesting requirements. The Company granted 790,078 restricted shares and Founder shares during the nine months ended September 30, 2015 with weighted-average grant date fair value of $2.12 per share. The Company did not grant any restricted shares or Founder Shares during the nine months ended September 30, 2016. As of September 30, 2016, there were 407,092 million unvested shares (Founder Shares and restricted shares) outstanding with a weighted-average grant date fair value of $1.89 per share. During the nine months ended September 30, 2015, pursuant to the share exchange transaction between the Company and TRACR, holders of TRACR ordinary shares, restricted ordinary shares and certain subscription rights to ordinary shares were granted replacement awards of Common Shares, restricted share awards and subscription rights to Common Shares in exchange for TRACR ordinary shares held and subscription rights for TRACR shares. Pursuant to the share exchange transaction, the Company issued 852,846 Common Shares to the founders of TRACR, 656,031 restricted shares to employee and non-employee advisors, and 459,217 Common Shares to Fay Corp. As of September 30, 2016, there was $2.0 million and $1.3 million of unrecognized compensation expense related to restricted shares and Founder Shares, respectively, to be recognized over a weighted-average period of 1.6 years and 1.5 years, respectively. Fay Corp. Awards A summary of the status of and changes in Common Shares held by Fay Corp. as of 2015, and September 30, 2016 is as follows: Shares Common Shares outstanding held by Fay Corp as of December 31, 2015 892,598 Common Shares issued to Fay Corp — Common Shares transferred from Fay Corp (618,414 ) Common Shares repurchased by the Company from Fay Corp (274,184 ) Common Shares outstanding held by Fay Corp as of September 30, 2016 — During the nine months ended September 30, 2016, Fay Corp. transferred a total of 618,414 Common Shares to two non-employee directors, one employee and a nonemployee advisor and the Company repurchased 274,184 Common Shares. Also during the nine months ended September 30, 2016, Fay Corp. transferred 328,014 shares of fully vested Common Shares to two nonemployee directors pursuant to the share exchange transaction with TRACR in March 2015. In addition, during the nine months ended September 30, 2016, the Company and Fay Corp. transferred 290,400 Common shares to a Founder, 268,093 of which are subject to vesting terms with a weighted average grant date fair value of $12.65. The unvested Common Shares are subject to repurchase by the Company upon termination of the holder’s service relationship with the Company as well as upon certain triggering events such as termination for cause, material breach of agreement and insolvency of the holder. The expense related to the Common Shares transferred to the Founder was $2.4 million for the nine months ended September 30, 2016. As of September 30, 2016, the Company had unrecognized equity-based compensation expense of $1.3 million related to this award which is expected to be recognized over a remaining weighted-average service period of 1.5 years. During the nine months ended September 30, 2015, Fay Corp. transferred 759,204 Common Shares, of which 131,203 Common Shares were transferred pursuant to the TRACR share exchange transaction, to two employees of the Company. The Common Shares are subject to service-based vesting conditions and unvested Common Shares may be repurchased in certain circumstances from the holder upon termination of the holder’s service relationship with the Company. Both vested and unvested shares are subject to repurchase at the original purchase price upon certain triggering events such as termination for cause, material breach of agreement and insolvency of the holder. As of December 31, 2015 and September 30, 2016, the Company had unrecognized equity-based compensation expense related to the Common Shares transferred from Fay Corp. to employees and non-employees with vesting restrictions of $1.8 million and $2.0 million, respectively. As of December 31, 2015 and September 30, 2016, the Company expects to recognize total unrecognized compensation cost over a remaining weighted-average period of 3.0 years and 2.0 years, respectively.

Net loss Per Share Attributable

Net loss Per Share Attributable to Common Shareholders	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Net loss Per Share Attributable to Common Shareholders	12. Net loss Per Share Attributable to Common Shareholders As described in Note 2 the Company computes basic and diluted earnings (loss) per share using a methodology that gives effect to the impact of outstanding participating securities (the “two-class method”). For the three months and nine months ended September 30, 2016 and 2015, resulted in net losses, there is no income allocation required under the two-class method or dilution attributed to weighted average shares outstanding in the calculation of diluted loss per share. The 4,429,311 shares issued in the IPO on October 19, 2016, and related conversion of 27,135,884 preferred shares and exercise of the call option for 328,017 shares are not included in the calculation as of September 30, 2016. Basic and diluted net loss per common share are calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Numerator: Net loss $ (14,694 ) $ (6,354 ) $ (40,300 ) $ (13,542 ) Loss attributable to noncontrolling interest 14 1 24 309 Net loss attributable to common stockholders – basic and diluted $ (14,680 ) $ (6,353 ) $ (40,276 ) $ (13,233 ) Denominator: Weighted-average common shares used in net loss per share attributable to common stockholders - basic and diluted 5,292,348 5,528,079 5,422,617 4,872,048 Net loss per share attributable to common stockholders - basic and diluted $ (2.77 ) $ (1.15 ) $ (7.43 ) $ (2.72 ) The following Common Share equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Convertible preferred shares 27,135,884 18,837,024 27,135,884 18,837,024 Dr. Emmanuelle Charpentier call option 328,017 328,017 328,017 328,017 Outstanding options 3,765,927 1,703,403 3,765,927 1,703,403 Unvested unissued restricted shares — 134,047 — 134,047 Unvested issued restricted shares 97,744 — 97,744 — 31,327,572 21,002,491 31,327,572 21,002,491

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2016
Related Party Transactions [Abstract]
Related Party Transactions	13. Related Party Transactions In connection with the Series A-3 Preferred Share financing, the Company paid $0.2 million on behalf of investors for legal and consulting costs incurred for the preparation and completion of the transaction. The Company is a party to intellectual property license agreements with Dr. Charpentier. In addition, Dr. Charpentier is a consultant to the Company and holds a 17.9% noncontrolling interest in TRACR. During the three months ended September 30, 2016 and 2015, and during the nine months ended September 30, 2016 and 2015, the Company paid Dr. Charpentier a total of $17,000, $8,000, $1.0 million, and $25,000, respectively, in consulting, licensing and other fees. As of December 31, 2015 and September 30, 2016, the Company owed Dr. Charpentier approximately $1.0 million, and $0.3 million, respectively of additional fees primarily related to the Vertex Collaboration Agreement and Bayer Joint Venture Agreement. During the nine months ended September 30, 2016, the Company formed a joint venture with Bayer. As a part of the agreement to form the joint venture, the Company also issued a convertible loan to Bayer, which then immediately converted in Series B Preferred Shares, see Note 6. During the three months ended September 30, 2016 and 2015, the Company recognized $0.4 million, $0, respectively, related to the performance of R&D services, and for the nine months ended September 30, 2016 and 2015, $0.4 million, and $0, respectively.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2016
Income Tax Disclosure [Abstract]
Income Taxes	14. Income Taxes During the nine months ended September 30, 2016 and September 30, 2015, the Company recorded an income tax provision of $0.1 million and an income tax benefit of $0.1 million, respectively, representing an effective tax rate of -0.2% and 0.5%, respectively. The income tax provision (benefit) is primarily attributable to the year-to-date pre-tax income (losses) earned by the Company’s U.S. and U.K. subsidiaries. The difference in the statutory tax rate and effective tax rate is primarily a result of the jurisdictional mix of earnings and losses that are not benefited. The Company maintains a partial valuation allowance against certain deferred tax assets for its subsidiaries in the UK and a full valuation allowance against its Swiss net deferred tax assets that are not more-likely-than-not realizable. As a results, the Company has not recognized a tax benefit related to the Swiss losses generated in the current periods.

Subsequent Events

Subsequent Events	9 Months Ended
	Sep. 30, 2016
Subsequent Events [Abstract]
Subsequent Events	15. Subsequent Events For the purposes of the interim financial statements as of September 30, 2016 and the period then ended, the Company has evaluated the subsequent events through November 21, 2016, the date the unaudited interim financial statements were issued. In September 2016, the Company formally offered an aggregate settlement up to $2.0 million to certain U.S common shareholders in order to release the Company from any and all obligations or claims concerning and/or arising out of the Company’s status as a PFIC or CFC for any taxable year from 2013 through 2015, including for potential lack of timely notification of the Company’s PFIC status for the year ended December 31, 2015, as described in Note 7. Following the formal settlement offer in September 2016, this settlement has been accepted by substantially all of the U.S. common shareholders representing $1.8 million of the aggregate settlement of $2.0 million. To date, the Company has made payments of $1.8 million under the terms of the accepted settlements. In October 2016, the Company completed its IPO, whereby the Company sold 4,429,311 Common Shares, inclusive of 429,311 Common Shares sold by the Company pursuant to the partial exercise of an overallotment option granted to the underwriters in connection with the offering, at a price to the public of $14.00 per share. The shares began trading on the NASDAQ Global Market on October 19, 2016. The aggregate net proceeds received by the Company from the offering were $54.1 million, after deducting underwriting discounts and commissions and other offering expenses payable by the Company. Concurrent with the IPO, the Company issued and sold 2,500,000 Common Shares to Bayer Global Investments B.V., in a private placement, at the IPO price of $14.00 per share, for aggregate net proceeds of $35.0 million. Upon the closing of the IPO, all 27,135,884 of the Company’s outstanding preferred shares converted into Common Shares on a one-for-one basis and the Company issued 328,017 Common Shares to Dr. Charpentier in exchange for the remaining non-controlling equity interest in TRACR pursuant to a call option agreement. Accordingly, in October 2016, TRACR became a wholly-owned subsidiary. On July 19, 2016, the Company’s shareholders approved the Company’s 2016 Stock Option and Incentive Plan, or 2016 Stock Option Plan, which became effective upon completing of the IPO in October 2016. The Company has reserved 7,271,779 Common Shares for the issuance of awards under the 2016 Stock Option Plan. On July 19, 2016, the Company’s shareholders approved the Company’s 2016 Employee Stock Purchase Plan, or 2016 ESPP, which became effective upon completing of the IPO in October 2016. The Company has reserved 413,226 Common Shares for the issuance of awards under the 2016 ESPP.

Summary of Significant Accoun22

Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2016
Accounting Policies [Abstract]
Unaudited Interim Financial Information	Unaudited Interim Financial Information 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 (the “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 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 Prospectus that forms a part of the Company’s Registration Statement on Form S-1 (File No. 333-213577), which was filed with the SEC pursuant to Rule 424(b)(4) on October 19, 2016 (the “Prospectus”). 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 representation of the results for the reported interim periods.
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies,” in the Prospectus. There have been no material changes to the significant accounting policies during the period ended September 30, 2016.
Basis of Presentation and Use of Estimates	Basis of Presentation and Use of Estimates The accompanying consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America (“GAAP”), and include the accounts of (i) the Company, (ii) its wholly-owned subsidiaries, CRISPR Ltd. and CRISPR Inc., and (iii) TRACR, a consolidated variable interest entity (“VIE”) and an 82.1% owned subsidiary as of December 31, 2015 and September 30, 2016. All intercompany accounts and transactions have been eliminated. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASUs”) of the Financial Accounting Standards Board (“FASB”). The Company accounts for its 50% investment share of Casebia Therapeutics LLP under the equity method of accounting. See Note 8 for further details. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, the Company’s management evaluates its estimates, which include, but are not limited to, equity-based compensation expense, revenue recognition, equity method investments, and reported amounts of expenses during the reported period. Significant estimates in these consolidated financial statements have been made in connection with the calculation of revenues, research and development expenses, equity-based compensation expense, fair value of Common Shares, fair value of intangible assets, and the provision for or benefit from income taxes. The Company bases its estimates on historical experience and other market-specific or other relevant assumptions that it believes to be reasonable under the circumstances. Actual results may differ from those estimates or assumptions. The Company utilizes significant estimates and assumptions in determining the fair value of its Common Shares. The Company utilized various valuation methodologies in accordance with the framework of the 2004 and 2013 American Institute of Certified Public Accountants Technical Practice Aids, Valuation of Privately- Held Company Equity Securities Issued as Compensation, to estimate the fair value of its Common Shares. Each valuation methodology includes estimates and assumptions that require the Company’s judgment. These estimates and assumptions include a number of objective and subjective factors, including external market conditions affecting the biotechnology industry sector, the prices at which the Company sold preferred shares, the superior rights and preferences of securities senior to the Company’s Common Shares at the time, the likelihood of achieving a liquidity event, such as an initial public offering or a sale of the Company, and the Company’s discounted cash flows from forecasted operations. Significant changes to the key assumptions used in the valuations could result in different fair values of Common Shares at each valuation date and materially affect the financial statements.
Amendment to Articles of Association	Amendment to Articles of Association In connection with preparing for its IPO, the Company’s board of directors and shareholders approved an amendment to the Company’s articles of association in July 2016. This amendment became effective upon registration in the Switzerland commercial register on July 27, 2016 and publication in the Swiss Official Gazette of Commerce on August 2, 2016. Pursuant to this amendment a 3 1 3
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, 2014-09 Revenue Recognition 2014-09 In August 2014, the FASB issued ASU No. 2014-15, In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments (“ASU 2016-15”). The guidance addresses diversity in practice in how certain cash receipts and cash payments are presented and classified in the statement of cash flows under Topic 230, Statement of Cash Flows, and other Topics. The updated guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-15 on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (“ASU 2016-02”), which applies to all leases and will require lessees to record most leases on the balance sheet, but recognize expense in a manner similar to the current standard. ASU 2016-02 is effective for fiscal years beginning after December 15, 2018 and interim periods within those years, which is the year ended December 31, 2019 for the Company. Entities are required to use a modified retrospective approach of adoption for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited. The Company is evaluating the new guidance and the expected effect on its consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718) (“ASU 2016-09”). The guidance changes how companies account for certain aspects of equity-based payments to employees. Entities will be required to recognize income tax effects of awards in the income statement when the awards vest or are settled. The guidance also allows an employer to repurchase more of an employee’s shares than it can under current guidance for tax withholding purposes providing for withholding at the employee’s maximum rate as opposed to the minimum rate without triggering liability accounting and to make a policy election to account for forfeitures as they occur. The updated guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. The Company is currently evaluating the impact of the adoption of ASU 2016-09 on its consolidated financial position and results of operations. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory (“ASU 2016-16”). The guidance aims to reduce the diversity in practice and complexity associated with accounting for the income tax consequences of intra-entity transfers of assets other than inventory. The new guidance will be effective for annual reporting periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods, with early adoption permitted in the first interim period only. The amendments are to be applied on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. The Company is currently evaluating the impact of the adoption of this standard on its consolidated financial statements. For a discussion of other recent accounting pronouncements please refer to Note 2, “Summary of Significant Accounting Policies,” in the Prospectus. The Company did not adopt any new accounting pronouncements during the three months ended September 30, 2016.

Property and Equipment, net (Ta

Property and Equipment, net (Tables)	9 Months Ended
	Sep. 30, 2016
Property, Plant and Equipment [Abstract]
Summary of Property and Equipment, Net	Property and equipment, net, consists of the following (in thousands): As of September 30, As of December 31, Computer equipment and software $ 110 $ 118 Furniture, fixtures, and other 351 238 Laboratory equipment 2,758 861 Leasehold improvements 124 88 Construction work in process 1,063 95 4,406 1,400 Accumulated Depreciation (544 ) (72 ) Property and equipment, net $ 3,862 $ 1,328

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2016
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities	Accrued expenses consist of the following (in thousands): As of September 30, 2016 As of December 31, 2015 Payroll and employee-related costs $ 1,987 $ 773 Research costs 1,752 910 Licensing fees 281 1,055 Professional fees 1,971 2,412 Intellectual property costs 4,232 2,592 Advance pay liability 2,007 — Other 172 688 Total $ 12,402 $ 8,430

Commitments and Contingencies (

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2016
Commitments and Contingencies Disclosure [Abstract]
Summary of Future Minimum Payments Required under Leases	Future minimum payments required under the leases as of December 31, 2015, are as follows (in thousands): Year Ending December 31: Amount 2016 $ 1,291 2017 1,341 2018 1,381 2019 1,422 2020 1,465 Thereafter 1,700 Total minimum lease payments $ 8,600

Share Capital (Tables)

Share Capital (Tables)	9 Months Ended
	Sep. 30, 2016
Equity [Abstract]
Schedule of Conditional Capital Reserved for Future Issuance	The Company had the following conditional capital reserved for future issuance: Type of Share Capital Conditional Capital As of September 30, As of December 31, Common Shares Charpentier Call Option 328,017 328,017 Common Shares Vested unissued restricted share awards under 2015 Plan 8,747 — Common Shares Unvested unissued restricted share awards under 2015 Plan 166,667 142,794 Common Shares Exercised options under the 2015 Plan 8,900 — Common Shares Outstanding stock options awards under 2015 Plan 3,558,998 1,939,986 Common Shares Reserved for future issuance under the 2015 Plan 52,322 33,567 Common Shares Shares available for IPO 16,399,005 — Common Shares Shares available for concurrent private placement 2,605,330 — Common Shares Shares available for bonds and similar debt instruments 4,919,700 — Common Shares Shares available for employee benefit plans 10,405,907 — Total 38,453,593 2,444,364

Equity-based Compensation (Tabl

Equity-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2016
Schedule of Total Equity-based Compensation Expense Recognized for Stock Options and Restricted Shares Granted to Employees and Non-employees	Total equity-based compensation expense is recognized for stock options and restricted shares granted to employees and non-employees and has been reported in the Company’s consolidated statements of operations as follows (in thousands): Three Months Ended Nine Months Ended 2016 2015 2016 2015 Research and development $ 1,343 $ 439 $ 2,834 $ 1,118 General and administrative 950 590 3,982 1,390 Total $ 2,293 $ 1,029 $ 6,816 $ 2,508
Fair Value of Underlying Common Shares on Each Measurement Date under Black-Scholes Option-Pricing Model	The Company estimates the fair value of each employee and non-employee stock award on the grant date using the Black-Scholes option-pricing model based on the following range of assumptions regarding the fair value of the underlying Common Shares on each measurement date: Three Months Ended Nine Months Ended September 30, 2016 2015 2016 2015 Employees: Weighted average expected volatility 84.6 % 76.0 % 81.8 % 76.1 % Expected term (in years) 6.0 6.0 6.0 6.0 Risk free interest rate 1.1 - 1.3 % 1.7 % 1.1 - 1.5 % 1.7 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 % Non employees: Weighted average expected volatility 93.6 % 84.0 % 93.6 % 84.0 % Expected term (in years) 10.0 10.0 10.0 10.0 Risk free interest rate 1.6 % 2.2 % 1.6 % 2.2 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 %
Employees and Non-employees [Member]
Summary of Stock Option Activity under 2015 Plan and from Treasury Shares for Employees and Non-employees	The following table summarizes stock option activity under the 2015 Plan and from Treasury Shares for employees and non-employees (intrinsic value in thousands): Stock Options Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2015 1,939,986 $ 2.31 9.7 $ 6,688 Granted 1,847,506 $ 10.95 Exercised (8,900 ) $ 1.97 Cancelled or forfeited (12,665 ) $ 4.96 Outstanding at September 30, 2016 3,765,927 $ 6.53 9.2 $ 22,764 Exercisable at September 30, 2016 695,053 $ 2.13 9.0 $ 7,255 Vested or expected to vest at September 30, 2016 (1) 3,112,563 $ 5.74 9.2 $ 21,288 (1) Represents the number of vested options at September 30, 2016 plus the number of unvested options expected to vest based on the unvested options outstanding at September 30, 2016.
Fay Corp Awards [Member]
Summary of Status and Changes in Common Shares	A summary of the status of and changes in Common Shares held by Fay Corp. as of 2015, and September 30, 2016 is as follows: Shares Common Shares outstanding held by Fay Corp as of December 31, 2015 892,598 Common Shares issued to Fay Corp — Common Shares transferred from Fay Corp (618,414 ) Common Shares repurchased by the Company from Fay Corp (274,184 ) Common Shares outstanding held by Fay Corp as of September 30, 2016 —

Net loss Per Share Attributab28

Net loss Per Share Attributable to Common Shareholders (Tables)	9 Months Ended
	Sep. 30, 2016
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss per Common Share	Basic and diluted net loss per common share are calculated as follows (in thousands, except share and per share data): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Numerator: Net loss $ (14,694 ) $ (6,354 ) $ (40,300 ) $ (13,542 ) Loss attributable to noncontrolling interest 14 1 24 309 Net loss attributable to common stockholders – basic and diluted $ (14,680 ) $ (6,353 ) $ (40,276 ) $ (13,233 ) Denominator: Weighted-average common shares used in net loss per share attributable to common stockholders - basic and diluted 5,292,348 5,528,079 5,422,617 4,872,048 Net loss per share attributable to common stockholders - basic and diluted $ (2.77 ) $ (1.15 ) $ (7.43 ) $ (2.72 )
Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share	The following Common Share equivalents, presented on an as converted basis, were excluded from the calculation of net loss per share for the periods presented, due to their anti-dilutive effect (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2016 2015 2016 2015 Convertible preferred shares 27,135,884 18,837,024 27,135,884 18,837,024 Dr. Emmanuelle Charpentier call option 328,017 328,017 328,017 328,017 Outstanding options 3,765,927 1,703,403 3,765,927 1,703,403 Unvested unissued restricted shares — 134,047 — 134,047 Unvested issued restricted shares 97,744 — 97,744 — 31,327,572 21,002,491 31,327,572 21,002,491

Organization and Operations - A

Organization and Operations - Additional Information (Detail) $ / shares in Units, $ in Thousands	Oct. 19, 2016USD ($)$ / sharesshares	Oct. 31, 2016$ / sharesshares	Sep. 30, 2016USD ($)	Dec. 31, 2015USD ($)	Mar. 24, 2015
Organization and operations [Line Items]
Company formation date			Oct. 28, 2013
Company formation country name			Basel, Switzerland
Accumulated deficit | $			$ (74,182)	$ (33,906)
Cash | $			$ 228,613	$ 155,961
Subsequent Event [Member]
Organization and operations [Line Items]
Conversion of preferred shares into common shares		1
IPO [Member]
Organization and operations [Line Items]
Convertible preferred stock conversion ratio			One-for-one
IPO [Member] | Subsequent Event [Member]
Organization and operations [Line Items]
Sale of common shares	4,429,311	4,429,311
Common shares price per share | $ / shares	$ 14	$ 14
Proceeds from issuance of common shares | $	$ 54,100
Conversion of preferred shares into common shares	27,135,884
Preferred shares conversion ratio	1
Overallotment Option [Member] | Subsequent Event [Member]
Organization and operations [Line Items]
Sale of common shares	429,311	429,311
Common shares price per share | $ / shares	$ 14	$ 14
CRISPR Therapeutics Limited [Member] | United Kingdom [Member]
Organization and operations [Line Items]
Subsidiary formation date			Feb. 7, 2014
CRISPR Therapeutics, Inc. [Member] | United States [Member]
Organization and operations [Line Items]
Subsidiary formation date			Feb. 16, 2015
Bayer Global Investments B.V [Member] | Subsequent Event [Member]
Organization and operations [Line Items]
Proceeds from issuance of common shares in private placement | $	$ 35,000
Bayer Global Investments B.V [Member] | Concurrent Private Placement [Member] | Subsequent Event [Member]
Organization and operations [Line Items]
Sale of common shares	2,500,000	2,500,000
Common shares price per share | $ / shares	$ 14	$ 14
TRACR Hematology Limited [Member]
Organization and operations [Line Items]
Formation date, VIE			Jan. 23, 2014
Relationship nature and extent of involvement in VIE			On January 23, 2014, the founders of the Company formed TRACR Hematology Limited (“TRACR”) in the United Kingdom, to further the development of the CRISPR/Cas9 technology into medicines for the treatment of blood-borne illnesses. As the Company was funding and managing TRACR’s operations in 2014, it has been consolidated by the Company from the date that the Company established a variable interest in TRACR in April 2014. In March 2015, the Company acquired 82.1% of the outstanding equity of TRACR in a share exchange transaction.
Purpose of VIE			To further the development of the CRISPR/Cas9 technology into medicines for the treatment of blood-borne illnesses.
Percentage of outstanding equity acquired			82.10%	82.10%	82.10%
TRACR Hematology Limited [Member] | Dr. Emmanuelle Charpentier [Member] | Call Option [Member] | IPO [Member] | Subsequent Event [Member]
Organization and operations [Line Items]
Conversion of preferred shares into common shares	328,017
Stock issued to acquire non-controlling equity interest	328,017

Summary of Significant Accoun30

Summary of Significant Accounting Policies - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2016	Feb. 12, 2016	Dec. 31, 2015	Mar. 24, 2015
Summary Of Significant Accounting Policies [Line Items]
Stock split, ratio	3.33
Stock split, description	3 1/3-for-one
TRACR Hematology Limited [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of outstanding equity acquired	82.10%		82.10%	82.10%
Casebia Therapeutics LLP [Member]
Summary Of Significant Accounting Policies [Line Items]
Equity method investment, ownership percentage	50.00%	50.00%

Property and Equipment, Net - S

Property and Equipment, Net - Summary of Property and Equipment, Net (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 4,406	$ 1,400
Accumulated Depreciation	(544)	(72)
Property and equipment, net	3,862	1,328
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	110	118
Furniture, Fixtures, and Other [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	351	238
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,758	861
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	124	88
Construction Work in Progress [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 1,063	$ 95

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 200,000	$ 27,000	$ 500,000	$ 27,000

Variable Interest Entities - Ad

Variable Interest Entities - Additional Information (Detail) $ in Millions	Mar. 24, 2015USD ($)Foundersshares	Sep. 30, 2016USD ($)
TRACR Hematology Limited [Member]
Variable Interest Entity [Line Items]
Deferred tax liability acquired | $		$ 0.1
Number of shares acquired	4,600
Percentage of shares acquired	82.10%
Number of founders | Founders	2
TRACR Hematology Limited [Member] | Call Option [Member]
Variable Interest Entity [Line Items]
Shares held by subsidiary	1,000
Remaining ownership percentage in VIE	17.90%
TRACR Hematology Limited [Member] | Additional Paid-in Capital [Member]
Variable Interest Entity [Line Items]
Decrease in noncontrolling interest | $	$ 0.1
TRACR Hematology Limited [Member] | Intangible Assets Net [Member]
Variable Interest Entity [Line Items]
Intangible assets acquired | $		$ 0.5
TRACR Hematology Limited [Member] | Founders' [Member] | Common Stock [Member]
Variable Interest Entity [Line Items]
Shares issued for acquisition	852,846
TRACR Hematology Limited [Member] | Employees and Non-employees [Member] | Restricted Common Stock [Member]
Variable Interest Entity [Line Items]
Shares issued for acquisition	656,031
TRACR Hematology Limited [Member] | Dr. Emmanuelle Charpentier [Member]
Variable Interest Entity [Line Items]
Remaining ownership percentage in VIE		17.90%
TRACR Hematology Limited [Member] | Dr. Emmanuelle Charpentier [Member] | Call Option [Member]
Variable Interest Entity [Line Items]
Shares issued on option exercise	328,017
Fay Participation Corporation [Member] | Common Stock [Member]
Variable Interest Entity [Line Items]
Shares issued for acquisition	459,217

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Accrued Liabilities, Current [Abstract]
Payroll and employee-related costs	$ 1,987	$ 773
Research costs	1,752	910
Licensing fees	281	1,055
Professional fees	1,971	2,412
Intellectual property costs	4,232	2,592
Advance pay liability	2,007
Other	172	688
Total	$ 12,402	$ 8,430

Convertible Loans - Additional

Convertible Loans - Additional Information (Detail) - USD ($)	Jan. 29, 2016	Oct. 26, 2015	Jan. 31, 2016	Dec. 07, 2015	Sep. 30, 2016
Debt Conversion [Line Items]
Aggregate net proceeds borrowed					$ 35,000,000
Conversion of convertible loans to Series B Preferred Shares					61,929,000
Gain on extinguishment of debt					$ 11,482,000
Vertex Convertible Loans [Member]
Debt Conversion [Line Items]
Borrowings under loan agreement		$ 40,000,000
Loan, accrued interest rate		2.50%
Loan agreement maturity date					Apr. 26, 2016
Aggregate net proceeds borrowed				$ 38,200,000
Conversion of convertible loans to Series B Preferred Shares	$ 200,000
Bayer Global Investments BV [Member]
Debt Conversion [Line Items]
Loan agreement maturity date					Jan. 29, 2016
Aggregate net proceeds borrowed	35,000,000
Borrowings under loan agreement					$ 35,000,000
Loan, accrued interest rate					2.00%
Bayer Healthcare LLC [Member]
Debt Conversion [Line Items]
Borrowings under loan agreement	$ 35,000,000
Series B Redeemable Convertible Preferred Shares [Member]
Debt Conversion [Line Items]
Preferred shares, shares issued upon conversion	2,859,278
Preferred shares, conversion price per share			$ 13.43
Series B Redeemable Convertible Preferred Shares [Member] | Vertex Convertible Loans [Member]
Debt Conversion [Line Items]
Conversion of convertible loans to Series B Preferred Shares			$ 38,400,000
Preferred shares, shares issued upon conversion	2,859,278
Preferred shares, conversion price per share	$ 13.43
Fair value of convertible loan	$ 26,900,000
Gain on extinguishment of debt	11,500,000
Series B Redeemable Convertible Preferred Shares [Member] | Bayer Healthcare LLC [Member]
Debt Conversion [Line Items]
Conversion of convertible loans to Series B Preferred Shares	$ 35,000,000
Preferred shares, shares issued upon conversion	2,605,330
Preferred shares, conversion price per share	$ 13.43
Fair value of convertible loan	$ 24,500,000
Allocated to convertible loan	27,000,000
Interest expense	$ 8,000,000

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	Jun. 07, 2016USD ($)	Oct. 31, 2016USD ($)	Sep. 30, 2016USD ($)Lease	Sep. 30, 2016USD ($)Lease	Sep. 30, 2015USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2016USD ($)LeaseSubleaseProgram	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)	Apr. 30, 2016USD ($)
Contingencies And Commitments [Line Items]
Number of non-cancellable operating leases | Lease								4
Number of expired leases | Lease			2	2				2
Lease expiration date								Sep. 30, 2016
Rental expense				$ 500,000	$ 400,000			$ 1,400,000	$ 700,000
Contractual obligation related to lease payments										$ 8,600,000
Letters of credit secured by cash held in restricted depository account			$ 3,153,000	3,153,000				3,153,000		700,000
Research and development expense				12,052,000	3,749,000			26,666,000	6,399,000
General and administrative expenses				4,107,000	$ 2,453,000			18,974,000	$ 7,164,000
Maximum obligation to make advance payments under the shareholders agreement								200,000
Formal Settlement Offer to U.S Common Shareholders [Member]
Contingencies And Commitments [Line Items]
Aggregate settlement amount			1,800,000
Payments for accepted settlement			1,800,000
Formal Settlement Offer to U.S Common Shareholders [Member] | Subsequent Event [Member]
Contingencies And Commitments [Line Items]
Payments for accepted settlement		$ 1,800,000
Maximum [Member]
Contingencies And Commitments [Line Items]
Required advance payments to shareholders										2,600,000
Maximum [Member] | Formal Settlement Offer to U.S Common Shareholders [Member]
Contingencies And Commitments [Line Items]
Aggregate settlement amount			2,000,000
Anagenesis Biotechnologies SAS [Member]
Contingencies And Commitments [Line Items]
Research and development expense								500,000
Upfront payment	$ 500,000
Payment regarding achievement of future clinical, regulatory and sales milestones	$ 89,000,000
PFIC [Member]
Contingencies And Commitments [Line Items]
General and administrative expenses				100,000				$ 2,000,000
Sponsored Research Agreement [Member]
Contingencies And Commitments [Line Items]
Number of research programs | Program								3
Research and development expense								$ 1,200,000
Scenario Forecast [Member] | Sponsored Research Agreement [Member]
Contingencies And Commitments [Line Items]
Research and development expense						$ 200,000	$ 400,000
Letter of Credit [Member]
Contingencies And Commitments [Line Items]
Letters of credit secured by cash held in restricted depository account											$ 2,500,000
Letters of credit secured by cash held in restricted depository account			3,200,000	3,200,000				$ 3,200,000		$ 700,000
Operating Lease, Primary Research Facility Space [Member]
Contingencies And Commitments [Line Items]
Lease expiration date								Feb. 28, 2022
Extended term of lease expiration								5 years
Office Space Lease [Member]
Contingencies And Commitments [Line Items]
Lease expiration date								Jan. 31, 2017
Number of sublease agreements | Sublease								2
Lease commencement date								Apr. 1, 2016
Contractual obligation related to lease payments			300,000	300,000				$ 300,000
Laboratory Space Lease [Member]
Contingencies And Commitments [Line Items]
Extended term of lease expiration								5 years
Lease commencement date								Dec. 31, 2016
Contractual obligation related to lease payments			$ 56,200,000	$ 56,200,000				$ 56,200,000
Lease expiration term								10 years

Commitments and Contingencies37

Commitments and Contingencies - Summary of Future Minimum Payments Required under Leases (Detail) $ in Thousands	Dec. 31, 2015USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	$ 1,291
2,017	1,341
2,018	1,381
2,019	1,422
2,020	1,465
Thereafter	1,700
Total minimum lease payments	$ 8,600

Significant Contracts - Additio

Significant Contracts - Additional Information (Detail) $ / shares in Units, € in Millions, SFr in Millions	Oct. 19, 2016USD ($)$ / sharesshares	Feb. 12, 2016USD ($)	Dec. 19, 2015shares	Oct. 26, 2015USD ($)Milestone	Oct. 31, 2016$ / sharesshares	Mar. 31, 2016USD ($)	Apr. 30, 2014USD ($)	Apr. 30, 2014CHF (SFr)	Sep. 30, 2016USD ($)	Mar. 31, 2016USD ($)	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)	Sep. 30, 2015USD ($)	Dec. 31, 2015USD ($)	Nov. 30, 2014EUR (€)	Nov. 30, 2014USD ($)
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									$ 12,052,000		$ 3,749,000	$ 26,666,000	$ 6,399,000
Research and development arrangement, description												The research collaboration will end on the earlier of the date on which Vertex has exercised six options to obtain exclusive/co-exclusive licenses with respect to a collaboration target, or the fourth anniversary of the effective date of the agreement. The research term may be extended as mutually agreed by the parties up to nine additional months to complete any research activities under the approved research plan that are incomplete on the fourth anniversary of the effective date.
Non-current deferred revenue									76,949,000			$ 76,949,000		$ 75,090,000
Date of joint venture agreement												Dec. 19, 2015
Cash contribution												$ 100,000
Fair value allocation of arrangement consideration paid									91,200,000			91,200,000
Equity method investment									35,686,000			35,686,000
Equity method losses												(686,000)
Bayer Healthcare LLC [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue related to research and development services									$ 400,000		0	400,000	0
Bayer Global Investments B.V [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Value of shares to be purchased via option through private placement | shares			35,000,000
Bayer Global Investments B.V [Member] | Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Proceeds from private placement	$ 35,000,000
Casebia Therapeutics LLP [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense												71,400,000
Nonrefundable upfront payment received						$ 20,000,000
Aggregate consideration receivable												$ 112,600,000
Revenue recognition, milestone method, revenue recognized		$ 0
Date of formation of joint venture entity												Feb. 12, 2016
Equity method investment, ownership percentage		50.00%							50.00%			50.00%
Cash contribution		$ 100,000
Remaining license fees to be received from joint venture entity		15,000,000
Royalty payments due to company from joint venture entity		0
Other payments due to company from joint venture entity		$ 0
Revenue related to research and development services									$ 500,000		0	$ 500,000	0
Convertible Loan									35,000,000			35,000,000
Cash contribution												100,000
Technology fee												34,900,000
Equity interest in the Joint Venture									36,400,000			36,400,000
Estimated revenue related to research and development services												6,300,000
Equity method losses									0			(700,000)
Net loss of joint venture									(3,000,000)			(77,100,000)
Unrealized losses from accounting of equity												(35,700,000)
Casebia Therapeutics LLP [Member] | Bayer Healthcare LLC [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense										$ 45,000,000
Equity method investment, ownership percentage		50.00%
Research and development funding term		5 years
Licensing Agreements [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fair value									71,400,000			71,400,000
License and Patent Holder Consent [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fair value allocation of arrangement consideration paid									63,600,000			63,600,000
Future Research and Development Services [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fair value allocation of arrangement consideration paid									600,000			600,000
Services [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Deferred revenue									35,000			35,000
Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									1,700,000		0	$ 4,500,000	0
Clinical milestone payment payable				$ 10,000,000
Nonrefundable upfront payment received				75,000,000
Potential milestone receivable				420,000,000
Number of days to terminate the collaboration agreement												90 days
Notice period in the event of material breach of collaboration agreement												90 days
Number of days to terminate the product												270 days
Best estimate selling price for research and development services				26,700,000
Best estimated selling price for single collaboration				37,700,000
Best estimated selling price for collaboration agreement				188,500,000
Estimated selling price for collaboration agreement				50,000,000
Aggregate consideration receivable				151,700,000
Revenue from collaboration agreement									1,200,000		0	$ 2,400,000	0
Non-current deferred revenue									76,300,000			76,300,000		$ 75,100,000
Concurrent Private Placement [Member] | Bayer Global Investments B.V [Member] | Subsequent Event [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Shares issued and sold | shares	2,500,000				2,500,000
Common shares price per share | $ / shares	$ 14				$ 14
Bayer Convertible Loans [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fair value of convertible loan									24,500,000			24,500,000
Fair value allocation of arrangement consideration paid									27,000,000			27,000,000
Debt instrument face amount									35,000,000			35,000,000
Debt instrument discount									8,000,000			8,000,000
Maximum [Member] | Casebia Therapeutics LLP [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue from collaboration agreement		$ 35,000,000
Maximum [Member] | Casebia Therapeutics LLP [Member] | Bayer Healthcare LLC [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense		$ 300,000,000
Research and Development Services [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Fair value									6,300,000			6,300,000
Research and Development Services [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate consideration receivable				17,800,000
Patent Assignment Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									0		0	0	0
Clinical milestone payment payable															€ 0.3	$ 400,000
Beta-Globin Collaboration [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Best estimated selling price for single collaboration				12,500,000
Non-Exclusive Research License and Exclusive License to Develop [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate consideration receivable				125,500,000
Non-Exclusive Research License and Co-Exclusive License to Develop [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate consideration receivable				8,400,000
Clinical Development Milestones [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				90,000,000
Regulatory Approval Milestone [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				235,000,000
Commercial Milestones [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				$ 75,000,000
Number of developmental milestone events | Milestone				2
Investigational New Drug Application ("IND") [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				$ 10,000,000
Investigational New Drug Application ("IND") [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				10,000,000
Exclusive Option Agreement [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				$ 10,000,000
Clinical Development And Regulatory Milestone [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of developmental milestone events | Milestone				9
Developmental Milestone Events [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Revenue recognition, milestone method, revenue recognized				$ 420,000,000
Commercial Milestone Event One [Member] | Minimum [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate consideration receivable				500,000,000
Commercial Milestone Event Two [Member] | Minimum [Member] | Vertex Pharmaceuticals Inc [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Aggregate consideration receivable				$ 1,000,000,000
CRISPR-Charpentier License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront fees paid for license							$ 100,000	SFr 0.1
Annual payments for consulting agreement									0		0	0	0
Research and development expense									0		0	300,000	0
TRACR-Charpentier License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research and development expense									$ 0		$ 0	$ 0	$ 0

Redeemable Convertible Prefer39

Redeemable Convertible Preferred Shares - Additional Information (Detail) SFr / shares in Units, $ / shares in Units, $ in Thousands, SFr in Millions

May 27, 2016USD ($)

Jan. 29, 2016USD ($)$ / shares

Oct. 31, 2016shares

Jun. 30, 2016USD ($)$ / sharesshares

Jan. 31, 2016USD ($)$ / sharesshares

May 31, 2015USD ($)$ / sharesshares

May 31, 2015CHF (SFr)SFr / sharesshares

Apr. 30, 2015USD ($)$ / sharesshares

Feb. 28, 2015USD ($)$ / shares

Feb. 28, 2015CHF (SFr)

Apr. 30, 2014USD ($)$ / sharesshares

Apr. 30, 2014CHF (SFr)

Oct. 31, 2013USD ($)$ / sharesshares

Oct. 31, 2013CHF (SFr)

Sep. 30, 2016USD ($)

Sep. 30, 2015USD ($)

Sep. 30, 2016SFr / sharesshares

Dec. 31, 2015SFr / shares

Dec. 31, 2015USD ($)shares

Feb. 28, 2015SFr / shares

Apr. 30, 2014SFr / sharesshares

Oct. 31, 2013SFr / sharesshares

Temporary Equity [Line Items]

Redeemable convertible preferred stock, par value | SFr / shares

SFr 0.03

SFr 0.03

Conversion of convertible loans | $

$ 61,929

Vertex Convertible Loans [Member]

Temporary Equity [Line Items]

Conversion of convertible loans | $

$ 200

Subsequent Event [Member]

Temporary Equity [Line Items]

Conversion ratio | shares

1

Converted shares | shares

27,135,884

Series A-1 Redeemable Convertible Preferred Shares [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, shares issued | shares

440,001

440,001

440,001

440,001

Redeemable convertible preferred stock, par value | (per share)

$ 1.28

SFr 0.03

0.03

SFr 1.14

Proceeds from issuance of redeemable convertible preferred shares

$ 600

SFr 0.5

Series A-2 Redeemable Convertible Preferred Shares [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, shares issued | shares

3,120,001

3,120,001

3,120,001

3,120,001

Redeemable convertible preferred stock, par value | (per share)

$ 3.47

SFr 0.03

0.03

SFr 3.05

Proceeds from issuance of redeemable convertible preferred shares

$ 5,100

SFr 4.5

$ 5,293

Series A-2 Redeemable Convertible Preferred Shares [Member] | Board of Directors [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, par value | (per share)

$ 1.82

SFr 1.60

Proceeds from issuance of redeemable convertible preferred shares

$ 5,300

SFr 5

Series A-2 Redeemable Convertible Preferred Shares [Member] | Preferred Stock Issuance [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, par value | (per share)

$ 1.65

SFr 1.45

Series A-3 Redeemable Convertible Preferred Shares [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, shares issued | shares

10,758,006

10,758,006

10,758,006

Redeemable convertible preferred stock, par value | SFr / shares

SFr 0.03

0.03

Proceeds from issuance of redeemable convertible preferred shares | $

$ 22,800

$ 22,800

22,850

22,850

Temporary equity, price per share | $ / shares

$ 4.24

Temporary equity share issued price per share | $ / shares

$ 2.12

Temporary equity, subscription receivable | $

$ 22,800

Series B Redeemable Convertible Preferred Shares [Member]

Temporary Equity [Line Items]

Redeemable convertible preferred stock, shares issued | shares

2,834,252

5,464,608

4,519,016

4,519,016

12,817,876

4,519,016

Redeemable convertible preferred stock, par value | SFr / shares

SFr 0.03

SFr 0.03

Proceeds from issuance of redeemable convertible preferred shares

$ 38,100

$ 30,500

SFr 28

$ 38,075

$ 30,478

Temporary equity, price per share | (per share)

$ 13.43

$ 6.74

SFr 6.20

Convertible debt, conversion price | $ / shares

$ 13.43

Series B Redeemable Convertible Preferred Shares [Member] | Vertex Convertible Loans [Member]

Temporary Equity [Line Items]

Conversion of convertible loans | $

$ 38,400

Convertible debt, conversion price | $ / shares

$ 13.43

Series B Redeemable Convertible Preferred Shares [Member] | Bayer Convertible Loans [Member]

Temporary Equity [Line Items]

Conversion of convertible loans | $

$ 35,000

Share Capital - Additional Info

Share Capital - Additional Information (Detail) - SFr / shares	9 Months Ended
	Sep. 30, 2016	Jul. 31, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Common stock, shares outstanding	5,307,845		5,528,079
Redeemable convertible preferred shares, outstanding	27,135,884		18,837,024
Common shares, par value	SFr 0.03	SFr 0.03	SFr 0.03
Redeemable convertible preferred stock, par value	SFr 0.03		SFr 0.03
Unvested restricted share award	97,744
Vested restricted shares in outstanding share capital	38,453,593		2,444,364
Common shares, conditional capital	38,453,593		2,444,364
Maximum [Member]
Class of Stock [Line Items]
Common shares, conditional capital		34,329,942
Restricted Shares [Member]
Class of Stock [Line Items]
Vested restricted shares in outstanding share capital	8,747
Employees Stock Options [Member]
Class of Stock [Line Items]
Exercised stock options in outstanding share capital	8,900

Share Capital - Schedule of Con

Share Capital - Schedule of Conditional Capital Reserved for Future Issuance (Detail) - shares	Sep. 30, 2016	Dec. 31, 2015
Class of Stock [Line Items]
Conditional capital reserved for future issuance	38,453,593	2,444,364
Charpentier Call Option [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	328,017	328,017
Shares Available for Bonds and Similar Debt Instruments [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	4,919,700
Shares Available for Employee Benefit Plans [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	10,405,907
IPO [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	16,399,005
Concurrent Private Placement [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	2,605,330
2015 Option and Grant Plan [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	218,989	33,567
2015 Option and Grant Plan [Member] | Vested Unissued Restricted Share Awards [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	8,747
2015 Option and Grant Plan [Member] | Unvested Unissued Restricted Share Awards [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	166,667	142,794
2015 Option and Grant Plan [Member] | Exercised Options [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	8,900
2015 Option and Grant Plan [Member] | Outstanding Stock Options Awards [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	3,558,998	1,939,986
2015 Option and Grant Plan [Member] | Reserved for Future Issuance [Member]
Class of Stock [Line Items]
Conditional capital reserved for future issuance	52,322	33,567

Equity-based Compensation - 201

Equity-based Compensation - 2015 Option and Grant Plan - Additional Information (Detail) - shares	Dec. 31, 2015	Aug. 31, 2016	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based payment award, number of shares granted			1,847,506	1,703,403
Common shares reserved for future grant	2,444,364		38,453,593
2015 Option and Grant Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation, options, exercised	0		8,900
Share-based payment award, number of options outstanding	1,939,986		3,558,998
Share-based payment award, number of shares granted	142,794	206,929	142,794
Share-based Compensation, options, vesting period		4 years	4 years
Share-based Compensation, options, contractual life		10 years	10 years
Common shares reserved for future grant	33,567		218,989

Equity-based Compensation - Sch

Equity-based Compensation - Schedule of Total Equity-based Compensation Expense Recognized for Stock Options and Restricted Shares Granted to Employees and Non-employees (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 2,293	$ 1,029	$ 6,816	$ 2,508
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	1,343	439	2,834	1,118
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 950	$ 590	$ 3,982	$ 1,390

Equity-based Compensation - Sum

Equity-based Compensation - Summary of Stock Option Activity under 2015 Plan and from Treasury Shares for Employees and Non-employees (Detail) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2015	Aug. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Granted			1,847,506	1,703,403
2015 Option and Grant Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Outstanding, Beginning Balance			1,939,986
Stock Options, Granted	142,794	206,929	142,794
Stock Options, Exercised	0		(8,900)
Stock Options, Outstanding, Ending Balance	1,939,986		3,558,998		1,939,986
Weighted-Average Remaining Contractual Term		10 years	10 years
2015 Option and Grant Plan [Member] | Employees and Non-employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Outstanding, Beginning Balance			1,939,986
Stock Options, Granted			1,847,506
Stock Options, Exercised			(8,900)
Stock Options, Cancelled or forfeited			(12,665)
Stock Options, Outstanding, Ending Balance	1,939,986		3,765,927		1,939,986
Stock Options, Exercisable			695,053
Stock Options, Vested or expected to vest			3,112,563
Weighted-Average Exercise Price, Outstanding, Beginning Balance			$ 2.31
Weighted-Average Exercise Price, Granted			10.95
Weighted-Average Exercise Price, Exercised			1.97
Weighted-Average Exercise Price, Cancelled or forfeited			4.96
Weighted-Average Exercise Price, Outstanding, Ending Balance	$ 2.31		6.53		$ 2.31
Weighted-Average Exercise Price, Exercisable			2.13
Weighted-Average Exercise Price, Vested or expected to vest			$ 5.74
Weighted-Average Remaining Contractual Term			9 years 2 months 12 days		9 years 8 months 12 days
Weighted-Average Remaining Contractual Term, Exercisable			9 years
Weighted-Average Remaining Contractual Term, Vested or expected to vest			9 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding Balance	$ 6,688		$ 22,764		$ 6,688
Aggregate Intrinsic Value, Exercisable			7,255
Aggregate Intrinsic Value, Vested or expected to vest			$ 21,288

Equity-based Compensation - Equ

Equity-based Compensation - Equity-based Compensation Expense - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Granted	1,847,506	1,703,403
Weighted-average exercise price, granted	$ 7.68	$ 3.01
Equity-based compensation expense not yet recognized, weighted-average service period for recognition	3 years 3 months 18 days		3 years 3 months 18 days
Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 2
Equity-based compensation expense not yet recognized, weighted-average service period for recognition	1 year 7 months 6 days
Performance-Based [Member] | Share-Based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock Options, Granted	429,998	261,389
TRACR Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued		131,203
TRACR Awards [Member] | Common Stock [Member] | Fay Participation Corporation [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued		459,217
Founders' Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 1.3
Equity-based compensation expense not yet recognized, weighted-average service period for recognition	1 year 6 months
Founders' Shares [Member] | Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted shares, granted	0	790,078
Restricted shares, weighted-average grant date fair value, issued		$ 2.12
Unvested restricted shares, vested	407,092,000,000
Unvested restricted shares, weighted-average grant date fair value, vested	$ 1.89
Founders Of TRACR [Member] | TRACR Awards [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued		852,846
Employees And Nonemployees Advisors [Member] | TRACR Awards [Member] | Restricted Shares [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued		656,031
Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 11.7		$ 4.2
Non Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total unrecognized compensation cost	$ 0.3		$ 0.1

Equity-based Compensation - Fai

Equity-based Compensation - Fair Value of Underlying Common Shares on Each Measurement Date under Black-Scholes Option-Pricing Model (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected volatility	84.60%	76.00%	81.80%	76.10%
Expected term (in years)	6 years	6 years	6 years	6 years
Risk free interest rate		1.70%		1.70%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Employee [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.10%		1.10%
Employee [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	1.30%		1.50%
Non Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average expected volatility	93.60%	84.00%	93.60%	84.00%
Expected term (in years)	10 years	10 years	10 years	10 years
Risk free interest rate	1.60%	2.20%	1.60%	2.20%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Equity-based Compensation - S47

Equity-based Compensation - Summary of Status and Changes in Common Shares (Detail) - Fay Corp Awards [Member] - Common Stock [Member]	9 Months Ended
	Sep. 30, 2016shares
Class of Stock [Line Items]
Common Shares outstanding held by Fay Corp, Beginning Balance	892,598
Common Shares issued to Fay Corp	0
Common Shares transferred from Fay Corp	(618,414)
Common Shares repurchased by the Company from Fay Corp	(274,184)

Equity-based Compensation - Fay

Equity-based Compensation - Fay Corp. Awards - Additional Information (Detail) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016USD ($)$ / sharesshares	Sep. 30, 2015USD ($)	Sep. 30, 2016USD ($)EmployeeNon_Employee_DirectorsNon_Employee_Advisor$ / sharesshares	Sep. 30, 2015USD ($)Employeeshares	Dec. 31, 2015USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation expense | $	$ 2,293	$ 1,029	$ 6,816	$ 2,508
Equity-based compensation expense not yet recognized, weighted-average service period for recognition			3 years 3 months 18 days		3 years 3 months 18 days
Founders' [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, weighted average grant date fair value | $ / shares	$ 12.65		$ 12.65
Equity-based compensation expense | $			$ 2,400
Unrecognized equity-based compensation expense | $	$ 1,300		$ 1,300
Equity-based compensation expense not yet recognized, weighted-average service period for recognition			1 year 6 months
Fay Corp Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued			290,400	759,204
Equity-based compensation expense not yet recognized, weighted-average service period for recognition			2 years		3 years
Fay Corp Awards [Member] | Founders' [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares expected to vest	268,093		268,093
Fay Corp Awards [Member] | Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued			618,414
Award transferred, number of individual | Non_Employee_Directors			2
Common shares repurchased			274,184
Equity-based compensation, number of shares expected to vest	328,014		328,014
Fay Corp Awards [Member] | Employee [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award transferred, number of individual | Employee			1
Unrecognized equity-based compensation expense | $					$ 1,800
Fay Corp Awards [Member] | Nonemployee Advisor [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award transferred, number of individual | Non_Employee_Advisor			1
Fay Corp Awards [Member] | Non Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized equity-based compensation expense | $	$ 2,000		$ 2,000
Fay Corp Awards [Member] | Non-employee Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award transferred, number of individual | Non_Employee_Directors			2
TRACR Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Equity-based compensation, number of shares issued				131,203
Award transferred, number of individual | Employee				2

Net Loss Per Share Attributab49

Net Loss Per Share Attributable to Common Shareholders - Additional Information (Detail) - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Earnings Per Share [Line Items]
Income allocated under the two-class method or dilution attributed to weighted average shares outstanding	$ 0	$ 0	$ 0	$ 0
Shares not included in the calculation of net loss per share	31,327,572	21,002,491	31,327,572	21,002,491
Dr. Emmanuelle Charpentier Call Option [Member]
Earnings Per Share [Line Items]
Shares not included in the calculation of net loss per share	328,017	328,017	328,017	328,017
Convertible Preferred Shares [Member]
Earnings Per Share [Line Items]
Shares not included in the calculation of net loss per share	27,135,884	18,837,024	27,135,884	18,837,024
IPO [Member]
Earnings Per Share [Line Items]
Shares not included in the calculation of net loss per share			4,429,311

Net Loss Per Share Attributab50

Net Loss Per Share Attributable to Common Shareholders - Schedule of Basic and Diluted Net Loss per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Numerator:
Net loss	$ (14,694)	$ (6,354)	$ (40,300)	$ (13,542)
Loss attributable to noncontrolling interest	14	1	24	309
Net loss attributable to common stockholders - basic and diluted	$ (14,680)	$ (6,353)	$ (40,276)	$ (13,233)
Denominator:
Weighted-average common shares used in net loss per share attributable to common stockholders - basic and diluted	5,292,348	5,528,079	5,422,617	4,872,048
Net loss per share attributable to common stockholders - basic and diluted	$ (2.77)	$ (1.15)	$ (7.43)	$ (2.72)

Net Loss Per Share Attributab51

Net Loss Per Share Attributable to Common Shareholders - Schedule of Antidilutive Securities Excluded from Computation of Net Loss per Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	31,327,572	21,002,491	31,327,572	21,002,491
Dr. Emmanuelle Charpentier Call Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	328,017	328,017	328,017	328,017
Employees Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	3,765,927	1,703,403	3,765,927	1,703,403
Unvested Unissued Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share		134,047		134,047
Unvested Issued Restricted Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	97,744		97,744
Convertible Preferred Shares [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of net loss per share	27,135,884	18,837,024	27,135,884	18,837,024

Related Party Transactions - Ad

Related Party Transactions - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Investors [Member] | Series A-3 Redeemable Convertible Preferred Shares [Member]
Related Party Transaction [Line Items]
Legal and consulting costs			$ 200,000
Dr. Emmanuelle Charpentier [Member] | TRACR Hematology Limited [Member]
Related Party Transaction [Line Items]
Noncontrolling interest in TRACR			17.90%
Payment of consulting, licensing and other fees	$ 17,000	$ 8,000	$ 1,000,000	$ 25,000
Related party transaction additional fees			300,000		$ 1,000,000
Bayer Healthcare LLC [Member]
Related Party Transaction [Line Items]
Revenue related to research and development services	$ 400,000	$ 0	$ 400,000	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Tax Disclosure [Abstract]
Income tax provision (benefit)	$ 8	$ 153	$ 84	$ (63)
Effective income tax rate			(0.20%)	0.50%

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail) - USD ($)	Oct. 19, 2016	Oct. 31, 2016	Sep. 30, 2016	Sep. 30, 2016	Jul. 19, 2016	Dec. 31, 2015
Subsequent Event [Line Items]
Common shares reserved for issuance of awards			38,453,593	38,453,593		2,444,364
IPO [Member]
Subsequent Event [Line Items]
Convertible preferred stock conversion ratio				One-for-one
Common shares reserved for issuance of awards			16,399,005	16,399,005
Concurrent Private Placement [Member]
Subsequent Event [Line Items]
Common shares reserved for issuance of awards			2,605,330	2,605,330
Subsequent Event [Member]
Subsequent Event [Line Items]
Conversion of convertible preferred stock into common stock | shares		1
Subsequent Event [Member] | Bayer Global Investments B.V [Member]
Subsequent Event [Line Items]
Proceeds from issuance of common shares in private placement	$ 35,000,000
Subsequent Event [Member] | IPO [Member]
Subsequent Event [Line Items]
Common shares sold	4,429,311	4,429,311
Common shares price per share	$ 14	$ 14
Proceeds from issuance of common shares	$ 54,100,000
Preferred shares outstanding	27,135,884
Conversion of convertible preferred stock into common stock | shares	27,135,884
Subsequent Event [Member] | IPO [Member] | Dr. Emmanuelle Charpentier [Member] | TRACR Hematology Limited [Member] | Call Option [Member]
Subsequent Event [Line Items]
Conversion of convertible preferred stock into common stock | shares	328,017
Subsequent Event [Member] | Overallotment Option [Member]
Subsequent Event [Line Items]
Common shares sold	429,311	429,311
Common shares price per share	$ 14	$ 14
Subsequent Event [Member] | Concurrent Private Placement [Member] | Bayer Global Investments B.V [Member]
Subsequent Event [Line Items]
Common shares sold	2,500,000	2,500,000
Common shares price per share	$ 14	$ 14
Formal Settlement Offer to U.S Common Shareholders [Member]
Subsequent Event [Line Items]
Aggregate settlement amount			$ 1,800,000
Payments for accepted settlement			1,800,000
Formal Settlement Offer to U.S Common Shareholders [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Payments for accepted settlement		$ 1,800,000
Maximum [Member] | Formal Settlement Offer to U.S Common Shareholders [Member]
Subsequent Event [Line Items]
Aggregate settlement amount			$ 2,000,000
2016 Stock Option and Incentive Plan [Member]
Subsequent Event [Line Items]
Common shares reserved for issuance of awards					7,271,779
2016 Employee Stock Purchase Plan [Member]
Subsequent Event [Line Items]
Common shares reserved for issuance of awards					413,226