Intellia Therapeutics (NTLA) 10-Q 9 Nov 23 2023 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2023	Nov. 03, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q3
Trading Symbol	NTLA
Entity Registrant Name	INTELLIA THERAPEUTICS, INC.
Entity Central Index Key	0001652130
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		89,554,891
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Shell Company	false
Entity File Number	001-37766
Entity Tax Identification Number	36-4785571
Entity Address, Address Line One	40 Erie Street
Entity Address, Address Line Two	Suite 130
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02139
City Area Code	857
Local Phone Number	285-6200
Entity Incorporation, State or Country Code	DE
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Current Assets:
Cash and cash equivalents	$ 168,027	$ 523,506
Marketable securities	686,761	669,116
Accounts receivable ($0 and $0.3 million, respectively, from related party)	6,491	3,768
Prepaid expenses and other current assets	32,214	20,407
Total current assets	893,493	1,216,797
Marketable securities - noncurrent	137,752	69,338
Property and equipment, net	33,800	27,921
Operating lease right-of-use assets	118,775	133,076
Equity method investment	17,166	32,455
Investments and other assets	42,363	40,527
Total Assets	1,243,349	1,520,114
Current Liabilities:
Accounts payable	3,553	5,154
Accrued expenses ($1.0 million and $1.6 million, respectively, from related party)	57,979	60,876
Current portion of operating lease liability	17,074	16,685
Current portion of deferred revenue ($0 and $19.9 million, respectively, from related party)	13,347	43,839
Total current liabilities	91,953	126,554
Deferred revenue, net of current portion	12,719	19,932
Long-term operating lease liability	101,263	114,018
Contingent consideration liability	0	24,026
Total liabilities	205,935	284,530
Commitments and contingencies (Note 6)
Stockholders’ Equity:
Common stock, $0.0001 par value; 240,000,000 and 120,000,000 shares authorized at September 30, 2023 and December 31, 2022, respectively; 89,097,821 and 87,103,007 shares issued and outstanding at September 30, 2023 and December 31, 2022, respectively	9	9
Additional paid-in capital	2,567,195	2,420,223
Accumulated other comprehensive loss	(3,572)	(7,461)
Accumulated deficit	(1,526,218)	(1,177,187)
Total stockholders’ equity	1,037,414	1,235,584
Total Liabilities and Stockholders’ Equity	$ 1,243,349	$ 1,520,114

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Accounts receivable, related party	$ 6,491	$ 3,768
Current portion of deferred revenue, related party	$ 0	$ 19,900
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	240,000,000	120,000,000
Common stock, shares issued	89,097,821	87,103,007
Common stock, shares outstanding	89,097,821	87,103,007
Related Party [Member]
Accounts receivable, related party	$ 0	$ 300
Accrued expenses, related party	$ 1,000	$ 1,600

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Collaboration revenue	$ 11,992	$ 13,266	$ 38,192	$ 38,548
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 113,696	$ 96,651	$ 326,088	$ 319,945
General and administrative	29,403	22,145	87,503	66,680
Total operating expenses	143,099	118,796	413,591	386,625
Operating loss	(131,107)	(105,530)	(375,399)	(348,077)
Other income (expense), net:
Interest income	12,740	1,945	37,373	3,188
Loss from equity method investment	(3,857)	(1,834)	(10,905)	(7,831)
Change in fair value of contingent consideration	0	(7,810)	(100)	(8,059)
Total other income (expense), net	8,883	(7,699)	26,368	(12,702)
Net loss	$ (122,224)	$ (113,229)	$ (349,031)	$ (360,779)
Net loss per share, basic	$ (1.38)	$ (1.49)	$ (3.96)	$ (4.78)
Net loss per share, diluted	$ (1.38)	$ (1.49)	$ (3.96)	$ (4.78)
Weighted average shares outstanding, basic	88,645	76,047	88,204	75,543
Weighted average shares outstanding, diluted	88,645	76,047	88,204	75,543
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	$ 142	$ 991	$ 1,649	$ (5,069)
Other comprehensive gain (loss) from equity method investment	154	(805)	2,240	(1,667)
Comprehensive loss	$ (121,928)	$ (113,043)	$ (345,142)	$ (367,515)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
Revenue from related party	$ 1,946	$ 4,414	$ 12,673	$ 15,612

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (349,031)	$ (360,779)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	6,510	5,541
Loss (gain) on disposal of property and equipment	5	(162)
Equity-based compensation	99,007	66,774
(Accretion) amortization of investment discounts and premiums	(19,590)	5,252
Loss from equity method investment	10,905	7,831
Deferral of equity method investment intra-entity profit on sales	6,624	8,530
Change in fair value of contingent consideration	100	8,059
In-process research and development expense	0	55,990
Changes in operating assets and liabilities:
Accounts receivable	(2,723)	(1,992)
Prepaid expenses and other current assets	(11,806)	(228)
Operating lease right-of-use assets	14,148	8,516
Other assets	(836)	(982)
Accounts payable	(1,419)	(5,334)
Accrued expenses	(3,008)	12,852
Deferred revenue	(37,705)	(46,739)
Operating lease liabilities	(12,213)	(6,547)
Net cash used in operating activities	(301,032)	(243,418)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(12,465)	(9,646)
Purchases of marketable securities	(754,689)	(192,598)
Maturities of marketable securities	689,868	437,387
Proceeds from sale of property and equipment	0	150
Acquired in-process research and development, net of cash acquired of $287	0	(44,832)
Net cash (used in) provided by investing activities	(77,286)	190,461
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from options exercised	5,604	13,984
Issuance of shares through employee stock purchase plan	2,051	1,068
Net cash provided by financing activities	23,839	77,192
Net (decrease) increase in cash, cash equivalents and restricted cash equivalents	(354,479)	24,235
Cash, cash equivalents and restricted cash equivalents, beginning of period	535,463	125,486
Cash, cash equivalents and restricted cash equivalents, end of period	180,984	149,721
Reconciliation of cash, cash equivalents and restricted cash equivalents to condensed consolidated balance sheet:
Cash and cash equivalents	168,027	141,194
Restricted cash equivalents, included in investments and other assets	12,957	8,527
Total cash, cash equivalents and restricted cash equivalents	180,984	149,721
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	1,552	2,180
Shares issued for Rewrite contingent consideration	24,126	0
Right-of-use asset acquired under operating lease	0	30,663
Contingent consideration liability assumed in asset acquisition	0	10,541
Proceeds from at-the-market offerings unpaid at period end	0	8,255
Non-cash trade-in of property and equipment	0	200
At The Market Offerings [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common stock	$ 16,184	$ 62,140

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Net of cash acquired	$ 287

Overview and Basis of Presentat

Overview and Basis of Presentation	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Overview and Basis of Presentation	1. Overview and Basis of Presentation Intellia Therapeutics, Inc. (“Intellia” or the “Company”) is a leading clinical-stage genome editing company, focused on developing potentially curative therapeutics using CRISPR/Cas9-based technologies. CRISPR/Cas9, an acronym for C lustered, R egularly I nterspaced S hort P alindromic R epeats (“CRISPR”)/CRISPR associated 9 (“Cas9”), is a technology for genome editing, the process of altering selected sequences of genomic deoxyribonucleic acid (“DNA”). To fully realize the transformative potential of CRISPR/Cas9-based technologies, Intellia is building a full-spectrum genome editing company, by leveraging its modular platform, to advance in vivo and ex vivo therapies for diseases with high unmet need by pursuing two primary approaches. For in vivo applications to address genetic diseases, the Company deploys CRISPR/Cas9 as the therapy that targets cells within the body. In parallel, the Company is developing ex vivo applications to address immuno-oncology and autoimmune diseases, where the Company uses CRISPR/Cas9 as the tool to create the engineered cell therapy. The Company’s deep scientific, technical and clinical development experience, along with its robust intellectual property (“IP”) portfolio, have enabled it to unlock broad therapeutic applications of CRISPR/Cas9 and related technologies to create new classes of genetic medicine. The condensed consolidated financial statements of the Company included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the financial statements and notes thereto included in the Company’s Annual Report on Form 10-K (“Annual Report”) for the year ended December 31, 2022. The unaudited condensed consolidated financial statements include the accounts of Intellia Therapeutics, Inc. and its wholly- owned subsidiary, Intellia Securities Corp. All intercompany balances and transactions have been eliminated in consolidation. Comprehensive loss is comprised of net loss, unrealized gain/loss on marketable securities and other comprehensive gain/loss from equity method investment. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates, judgments and assumptions that affect the amounts reported in the financial statements and accompanying notes. Significant estimates in these condensed consolidated financial statements have been made in connection with the calculation of revenues, research and development expenses, valuation of equity and fair value method investments, contingent consideration and equity-based compensation expense. The Company bases its estimates on historical experience and various other assumptions that management believes to be reasonable under the circumstances at the time such estimates are made. Actual results could differ from those estimates. The Company periodically reviews its estimates in light of changes in circumstances, facts and experience. The effects of material revisions in estimates, if any, would be reflected in the condensed consolidated financial statements prospectively from the date of the change in estimate. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period. Liquidity Since its inception through September 30, 2023 , the Company has raised an aggregate of $ 2,424.1 million to fund its operations through its initial public offering (“IPO”) and concurrent private placements, follow-on public offerings, at-the-market offerings and the sale of convertible preferred stock, as well as through its collaboration agreements. The Company expects that its cash, cash equivalents and marketable securities as of September 30, 2023 will enable the Company to fund its ongoing operating expenses and capital expenditure requirements for at least the twelve-month period following the issuance of these condensed consolidated financial statements.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies The Company’s significant accounting policies are described in Note 2, “Summary of Significant Accounting Policies” to the consolidated financial statements included in the Annual Report for the year ended December 31, 2022. There have been no material changes to these policies during the nine months ended September 30, 2023 .

Marketable Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	3. Marketable Securities The following table summarizes the Company’s available-for-sale marketable securities as of September 30, 2023 and December 31, 2022 at net book value: September 30, 2023 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 330,875 $ 3 $ ( 935 ) $ 329,943 Financial institution debt securities 319,226 40 ( 688 ) 318,578 Corporate debt securities 115,344 4 ( 306 ) 115,042 Other asset-backed securities 61,188 - ( 238 ) 60,950 Total $ 826,633 $ 47 $ ( 2,167 ) $ 824,513 December 31, 2022 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 244,562 $ 62 $ ( 1,938 ) $ 242,686 Financial institution debt securities 380,891 - ( 1,030 ) 379,861 Corporate debt securities 102,059 - ( 509 ) 101,550 Other asset-backed securities 14,703 - ( 346 ) 14,357 Total $ 742,215 $ 62 $ ( 3,823 ) $ 738,454 The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. At September 30, 2023 and December 31, 2022 , the balance in the Company’s accumulated other comprehensive loss was composed of activity related to the Company’s available-for-sale marketable securities and equity method investment. There were no material realized gains or losses in the nine months ended September 30, 2023 or for the year ended December 31, 2022; therefore, the Company did not reclassify any amounts out of accumulated other comprehensive loss during this period. The Company generally does not intend to sell any investments prior to recovery of their amortized cost basis for any investment in an unrealized loss position. As such, the Company has classified these losses as temporary in nature. The Company’s available-for-sale securities that are classified as short-term marketable securities in the condensed consolidated balance sheet mature within one year or less as of the balance sheet date. Available-for-sale securities that are classified as noncurrent in the condensed consolidated balance sheet are those that mature after one year but within five years from the balance sheet date and that the Company does not intend to dispose of within the next twelve months. At September 30, 2023 and December 31, 2022, the Company did not hold any investments that matured beyond five years of the balance sheet date.

Fair Value Measurements

Fair Value Measurements	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The Company classifies fair value-based measurements using a three-level hierarchy that prioritizes the inputs used to measure fair value. This hierarchy requires entities to maximize the use of observable inputs and minimize the use of unobservable inputs. The three levels of inputs used to measure fair value are as follows: Level 1, quoted market prices (unadjusted) in active markets for identical assets or liabilities; Level 2, observable inputs other than quoted market prices included in Level 1, such as quoted market prices for markets that are not active or other inputs that are observable or can be corroborated by observable market data; and Level 3, unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities, including certain pricing models, discounted cash flow methodologies and similar techniques that use significant unobservable inputs. As of September 30, 2023 and December 31, 2022, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of September 30, 2023 Total Level 1 Level 2 Level 3 (In thousands) Assets Cash equivalents and restricted cash equivalents $ 139,880 $ 139,880 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 329,943 77,781 252,162 - Financial institution debt securities 318,578 - 318,578 - Corporate debt securities 115,042 - 115,042 - Other asset-backed securities 60,950 - 60,950 - Total marketable securities 824,513 77,781 746,732 - Total Assets $ 964,393 $ 217,661 $ 746,732 $ - Fair Value as of December 31, 2022 Total Level 1 Level 2 Level 3 (In thousands) Assets Cash equivalents and restricted cash equivalents $ 534,581 $ 534,581 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 242,686 172,939 69,747 - Financial institution debt securities 379,861 - 379,861 - Corporate debt securities 101,550 - 101,550 - Other asset-backed securities 14,357 - 14,357 - Total marketable securities 738,454 172,939 565,515 - Total Assets $ 1,273,035 $ 707,520 $ 565,515 $ - Certain of the Company’s financial assets, including cash equivalents, restricted cash equivalents and marketable securities, have been initially valued at the transaction price, and subsequently revalued at the end of each reporting period, utilizing third party pricing services or other observable market data. The pricing services utilize industry standard valuation models and observable market inputs to determine value. Other financial instruments, including accounts receivable, accounts payable and accrued expense, are carried at cost, which approximates fair value due to the short duration and term to maturity. As discussed further in Note 9, under the Rewrite Merger Agreement, the Rewrite Holders received a $ 25.0 million research milestone payment in February of 2023, paid in a combination of $ 0.9 million in cash and the remainder in the Company’s common stock. The milestone payable in the Company’s common stock resulted in liability classification under ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). This contingent consideration liability was carried at fair value which was estimated by applying a probability-based model, which utilized inputs based on timing of achievement that were unobservable in the market. The contingent consideration liability was classified within Level 3 of the fair value hierarchy until it was settled in February of 2023. The following table reconciles the change in fair value of the contingent consideration liability based on the level 3 inputs listed below (in thousands): For the Nine Months Balance at December 31, 2022 $ 24,026 Change in fair value 100 Payment of contingent consideration ( 24,126 ) Balance at September 30, 2023 $ - December 31, 2022 Discount rate 10.1 % Probability of achievement 100 % Projected year of achievement 2023

Accrued Expenses

Accrued Expenses	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Accrued Expenses	5. Accrued Expenses Accrued expenses consisted of the following: September 30, December 31, 2023 2022 (In thousands) Accrued research and development $ 24,241 $ 32,684 Employee compensation and benefits 21,006 21,778 Accrued legal and professional expenses 1,649 1,457 Accrued other 11,083 4,957 Total accrued expenses $ 57,979 $ 60,876

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies Litigation There have been no material changes to any outstanding litigation, nor is the Company a party to any new litigation, since December 31, 2022. For further information please see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2022. License Agreements The Company is party to license agreements, which may include contingent payments. These payments will become payable if and when certain development, regulatory and commercial milestones are achieved. As of September 30, 2023 , the satisfaction and timing of the contingent payments is uncertain and not reasonably estimable.

Collaborations and Other Arrang

Collaborations and Other Arrangements	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborations and Other Arrangements	7. Collaborations and Other Arrangements To accelerate the development and commercialization of CRISPR/Cas9-based products in multiple therapeutic areas, the Company has formed, and intends to seek other opportunities to form, strategic alliances with collaborators who can augment its leadership in CRISPR/Cas9 therapeutic development. As of September 30, 2023, the Company’s accounts receivable were related to its collaborations with Regeneron Pharmaceuticals, Inc. (“Regeneron”), SparingVision SAS (“SparingVision”), Kyverna Therapeutics, Inc. (“Kyverna”), AvenCell Therapeutics, Inc. (“AvenCell”) and ONK Therapeutics, Ltd. (“ONK”), and the Company’s contract liabilities were related to its collaborations with Regeneron and SparingVision. As of December 31, 2022, the Company’s accounts receivable were related to its collaborations with Regeneron, AvenCell, SparingVision and ONK, and the Company’s contract liabilities were related to its collaborations with Regeneron, AvenCell, SparingVision and Kyverna. The following table presents changes in the Company’s accounts receivable and contract liabilities during the nine months ended September 30, 2023 and 2022 (in thousands): Balance at Additions Deductions Balance at End Nine Months Ended September 30, 2023 Accounts receivable $ 3,768 $ 15,287 $ ( 12,564 ) $ 6,491 Contract liabilities - deferred revenue $ 63,771 $ - $ ( 37,705 ) $ 26,066 Balance at Additions Deductions Balance at End Nine Months Ended September 30, 2022 Accounts receivable $ 2,031 $ 8,678 $ ( 6,686 ) $ 4,023 Contract liabilities - deferred revenue $ 127,235 $ - $ ( 46,739 ) $ 80,496 During the nine months ended September 30, 2023 and 2022, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Nine Months Ended September 30, Revenue recognized in the period from: 2023 2022 Amounts included in the contract liability at the beginning of the period $ 31,081 $ 38,208 Costs to obtain and fulfill a contract The Company has not incurred significant expenses to obtain collaboration agreements and costs to fulfill those contracts do not generate or enhance resources of the Company. As such, no costs to obtain or fulfill a contract have been capitalized in any period. Regeneron Pharmaceuticals, Inc. License and Collaboration Agreement In April 2016, the Company entered into a license and collaboration agreement with Regeneron (as amended from time to time, the “2016 Regeneron Agreement”). The 2016 Regeneron Agreement has two principal components: i) a product development component under which the parties will research, develop and commercialize CRISPR/Cas-based therapeutic products primarily focused on genome editing in the liver, and ii) a technology collaboration component, pursuant to which the Company and Regeneron will engage in research-related activities aimed at discovering and developing novel technologies and improvements to CRISPR/Cas technology to enhance the Company’s genome editing platform. Under this agreement, the Company also may access the Regeneron Genetics Center and proprietary mouse models to be provided by Regeneron for a limited number of the Company’s liver programs. At the inception of the 2016 Regeneron Agreement, Regeneron selected the first of its 10 targets, transthyretin (“ATTR”) amyloidosis, which is subject to a co-development and co-promotion agreement between the Company and Regeneron (the “ATTR Co/Co”). In May 2020, the Company entered into (i) amendment no. 1 (the “2020 Regeneron Amendment”) to the 2016 Regeneron Agreement, (ii) co-development and co-funding agreements for the treatment of hemophilia A and hemophilia B (the “Hemophilia Co/Co”) agreements and (iii) a stock purchase agreement. The collaboration expansion builds upon the jointly developed targeted transgene insertion capabilities designed to durably restore missing therapeutic protein, and to overcome the limitations of traditional gene therapy. The technology collaboration was extended until April 2024, at which point Regeneron would have an option to renew for an additional two years. The 2020 Regeneron Amendment also granted Regeneron exclusive rights to develop products for five additional in vivo CRISPR/Cas-based therapeutic liver targets and non-exclusive rights to independently develop and commercialize up to 10 ex vivo gene edited products made using certain defined cell types. In October 2023, Regeneron notified the Company that it was exercising its one-time option to extend the technology collaboration term for an additional two years , until April 2026 , in exchange for a nonrefundable payment of $ 30 million due in April 2024. In September 2023, Regeneron and Intellia further expanded the research collaboration (the “2023 Regeneron Amendment”) to develop additional in vivo CRISPR-based gene editing therapies focused on neurological and muscular diseases. The collaboration will leverage Intellia’s proprietary Nme2 CRISPR/Cas9 genome editing systems adapted for viral vector delivery and designed to precisely modify a target gene and Regeneron’s proprietary antibody-targeted adeno-associated virus vectors and delivery systems. Under the terms of the expanded research collaboration, the companies will initially research two in vivo non-liver targets. Intellia will lead the design of the editing methodology and Regeneron will lead the design of the targeted viral vector delivery approach and the parties will share research costs equally. Each party will have the opportunity to lead potential development and commercialization for one product candidate, and the party that is not leading development and commercialization will have the option to enter into a co-development and co-promotion agreement for the target. Since December 31, 2022, there have been no material changes to the key terms of the 2016 Regeneron Agreement, ATTR Co/Co or Hemophilia Co/Co (the “Regeneron Agreements”), other than as described above. Revenue Recognition – Collaboration Revenue. Through September 30, 2023 , excluding amounts allocated to Regeneron’s purchase of the Company’s common stock, the Company recorded $ 145.0 million in upfront payments under the Regeneron Agreements and $ 46.1 million for research and development services, primarily under the ATTR Co/Co agreement. Through September 30, 2023 , the Company has recognized $ 196.5 million of collaboration revenue under all arrangements, including $ 9.3 million and $ 23.5 million during the three and nine months ended September 30, 2023, respectively, and $ 6.5 million and $ 18.6 million during the three and nine months ended September 30, 2022, respectively, in the condensed consolidated statements of operations and comprehensive loss. This includes $ 5.5 million and $ 14.2 million during the three and nine months ended September 30, 2023 and $ 4.0 million and $ 8.7 million during the three and nine months ended September 30, 2022, respectively , primarily representing payments due from Regeneron pursuant to the ATTR Co/Co agreement. These revenues are offset in part by contra-revenue related to the Hemophilia Co/Co agreements amounting to approximately $ 1.8 million and $ 7.6 million during the three and nine months ended September 30, 2023 and $ 3.2 million and $ 6.9 million during the three and nine months ended September 30, 2022, respectively. As of September 30, 2023 , there was approximately $ 12.0 million of the aggregate transaction price remaining to be recognized, which the Company has been recognizing through April 2024 in accordance with the terms of the 2020 Regeneron Amendment. As of September 30, 2023 and December 31, 2022 , the Company had accounts receivable of $ 5.5 million and $ 3.2 million, respectively, and deferred revenue of $ 12.0 million and $ 28.8 million, respectively, related to Regeneron Agreements. AvenCell Therapeutics, Inc. In July 2021, the Company entered into two agreements with AvenCell, a privately held chimeric antigen receptor T (“CAR-T”) cell therapy company formed on that date in a joint venture between the Company, Cellex Cell Professionals GmbH (“Cellex”) and funds managed by Blackstone Life Sciences Advisors L.L.C. (“BXLS”): (i) a license and collaboration agreement (the “AvenCell LCA”), under which the Company will collaborate to develop allogeneic universal CAR-T cell therapies and which granted AvenCell a license to develop and commercialize genome edited universal CAR-T cell therapies (limited to its use with their switchable, universal CAR-T cell UniCAR and RevCAR platforms); and (ii) a co-development and co-funding agreement (the “AvenCell Co/Co”), under which the Company would co-develop and co-commercialize allogeneic universal CAR-T cell products for an immuno-oncology indication. In November 2022, the Company decided to re-prioritize its ex vivo programs and terminated the AvenCell Co/Co, effectively turning over control of the program to AvenCell. The Company’ s obligations under the terminated agreement were completed in the second quarter of 2023. The Company also has one option to enter into an additional co-development and co-funding agreement for a payment of $ 30.0 million to AvenCell. Since December 31, 2022, there have been no other material changes to the key terms of the AvenCell LCA and AvenCell Co/Co agreements. Revenue Recognition – Collaboration Revenue. The Company recognized $ 1.9 million and $ 13.2 million in revenue related to the AvenCell LCA for the three and nine months ended September 30, 2023 , respectively, after eliminating $ 1.0 million and $ 6.6 million during those respective periods in intra-entity profits, which will be deferred and recognized if and when AvenCell commercializes a product with the Company ’ s license or abandons the related project. Until such time, this revenue is indefinitely deferred and excluded from the results of operations of the Company. The Company recognized no revenue in the three months ended September 30, 2023 and $ 0.6 million in contra-revenue in the nine months ended September 30, 2023 related to the AvenCell Co/Co agreement. The Company recognized $ 1.3 million and $ 1.4 million in contra-revenue in the three and nine months ended September 30, 2022, respectively, related to the AvenCell Co/Co agreement. As of September 30, 2023 , there was no remaining transaction price of the AvenCell LCA remaining to be recognized. The Company had $ 9.0 thousand in accounts receivable and no deferred revenue related to the AvenCell agreements as of September 30, 2023. As of December 31, 2022 , the Company had $ 0.3 million in accounts receivable and deferred revenue of $ 19.9 million related to the AvenCell agreements. SparingVision SAS In October 2021, the Company and SparingVision, a genomic medicine company developing vision saving treatments for ocular diseases, entered into a license and collaboration agreement (the “SparingVision LCA”) to develop novel genomic medicines utilizing CRISPR/Cas9 technology for the treatment of ocular diseases. Since December 31, 2022, there have been no material changes to the key terms of the SparingVision LCA agreement. Revenue Recognition – Collaboration Revenue. The Company recognized $ 0.4 million and $ 1.3 million in revenue related to the SparingVision LCA for the three and nine months ended September 30, 2023 , respectively. The Company did no t recognize collaboration revenue in the three and nine months ended September 30, 2022 related to the SparingVision LCA. As of September 30, 2023 and December 31, 2022 , the Company had $ 0.7 million and $ 0.1 million in accounts receivable, respectively, related to the SparingVision LCA. As of September 30, 2023 and December 31, 2022 , the Company had deferred revenue of $ 14.1 million and $ 14.7 million, respectively, related to the SparingVision LCA, which is expected to be recognized over a six to nine year period from the signing of the agreement. Kyverna Therapeutics, Inc. In December 2021, the Company and Kyverna, a cell therapy company engineering a new class of therapies for autoimmune and inflammatory diseases, entered into a license and collaboration agreement (the “Kyverna LCA”), for the development of an allogeneic CD19 CAR-T cell therapy for the treatment of a variety of B cell-mediated autoimmune diseases. Since December 31, 2022, there have been no material changes to the key terms of the Kyverna LCA agreement. Revenue Recognition – Collaboration Revenue. The Company had recognized revenue from the Kyverna LCA in full as of March 31, 2023, including $ 0.4 million in revenue recorded in 2023 . The Company recognized approximately $ 0.1 million in revenue in the three and nine months ended September 30, 2023 related to materials shipped to Kyverna. The Company recognized $ 2.3 million and $ 4.3 million in collaboration revenue for the three and nine months ended September 30, 2022, respectively, related to the Kyverna LCA. As of September 30, 2023 , the Company had $ 0.1 million in accounts receivable related to the shipments made to Kyverna. As of December 31, 2022 , the Company had no accounts receivable and deferred revenue of $ 0.4 million related to Kyverna. ONK Therapeutics, Ltd. On February 12, 2022, the Company entered into a license, collaboration and option agreement (the “ONK LCA”) with ONK, an innovative company dedicated to developing optimally engineered natural killer (“NK”) cell therapies to cure patients with cancer. Since December 31, 2022, there have been no material changes to the key terms of the ONK LCA agreement. Revenue Recognition – Collaboration Revenue. The Company recognized $ 0.2 million in revenue for each of the three and nine month periods ended September 30, 2023 related to materials shipped in accordance with the ONK LCA. There was no revenue recognized in the three and nine months ended September 30, 2022 related to the ONK LCA. The Company had $ 0.2 million and $ 0.1 million in accounts receivable related to the ONK LCA at September 30, 2023 and December 31, 2022, respectively .

Equity-Method Investment and Ot

Equity-Method Investment and Other Investments	9 Months Ended
	Sep. 30, 2023
Equity Method Investments and Joint Ventures [Abstract]
Equity-Method Investment and Other Investments	8. Equity-Method Investment and Other Investments AvenCell Therapeutics, Inc. On July 30, 2021, the Company finalized a transaction in which the Company, Cellex and BXLS established AvenCell, a joint venture and privately held company. In exchange for contributing an exclusive license to the joint venture, the Company entered into a Preferred Stock Purchase Agreement with AvenCell for a 33.33 % equity interest in AvenCell at the time of the initial closing. Cellex and BXLS each equally owned the remaining 66.67 % at that time. The Company has significant influence over, but does not control, AvenCell through its noncontrolling representation on AvenCell’s board of directors and the Company’s equity interest in AvenCell. The Company has determined that the preferred stock it owns is in-substance common stock. The Company is not the primary beneficiary as it does not have the power to direct the activities of AvenCell that most significantly impact AvenCell’s economic performance. Accordingly, the Company accounts for its investment using the equity method of accounting. The Company recorded the initial investment in AvenCell of $ 62.9 million in “Equity method investments” on its condensed consolidated balance sheet. Due to the timing and availability of AvenCell’s financial information, the Company records its share of losses from AvenCell on a quarterly basis on a one-quarter lag. Accordingly, during the third quarter of 2023, the Company recorded its share of the three months of AvenCell’s losses generated in the second quarter of 2023 in the Company’s operating results and other comprehensive loss. These adjustments resulted in a reduction of the Company’ s investment by $ 3.7 million and $ 8.7 million for the three and nine months ended September 30, 2023 , respectively. The elimination of the intra-entity profit component of $ 1.0 million and $ 6.6 million (see Note 7) in the three and nine months ended September 30, 2023 , respectively, resulted in a further reduction in the balance of the investment in AvenCell, bringing the carrying value of the investment to $ 17.2 million as of September 30, 2023. The Company is not aware of any material events or transactions during the quarter ended September 30, 2023 that would warrant additional disclosure or recognition in the financial statements. At September 30, 2023, the maximum exposure to loss is limited to the Company’s equity investment in the joint venture. SparingVision SAS In connection with the SparingVision LCA (see Note 7), the Company received 83,316 shares of SparingVision Series A2 Preferred Stock (“Series A2”). Attached to each share of Series A2, the Company received three warrants for the right to purchase additional Series A2 shares at designated prices that are subject to certain vesting conditions (collectively referred to as the “SparingVision investments”). The Company accounts for the SparingVision investments using the measurement alternative as SparingVision is a private company and there is no readily observable transaction price. The Company recorded the initial investment in SparingVision of $ 14.8 million in “Investments and other assets” on its condensed consolidated balance sheet. There was no change in the observable price or impairment of the SparingVision investment as of September 30, 2023. Kyverna Therapeutics, Inc. In connection with the Kyverna LCA (see Note 7), the Company received 3,739,515 shares of Kyverna Series B Preferred Stock (“Series B”) with a fair value of $ 7.0 million. The Company separately made an additional investment in Kyverna, purchasing 1,602,649 shares of Series B in exchange for $ 3.0 million in cash (collectively referred to as the “Kyverna investments”). The Company accounts for the Kyverna investments using the measurement alternative as Kyverna is a private company and there is no readily observable transaction price. The Company recorded the initial investment in Kyverna of $ 10.0 million in “Investments and other assets” on its condensed consolidated balance sheet. There was no change in the observable price or impairment of the Kyverna investment as of September 30, 2023 .

Rewrite Acquisition

Rewrite Acquisition	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Rewrite Acquisition	9. Rewrite Acquisition On February 2, 2022, the Company entered into an Agreement and Plan of Merger by and among the Company, Rewrite Therapeutics, Inc. (“Rewrite”), RW Acquisition Corp. and Shareholder Representative Services, LLC as Securityholder representative (the “Rewrite Merger Agreement”). Under the Rewrite Merger Agreement, the Company paid Company Securityholders (as defined in the Rewrite Merger Agreement) (the “Rewrite Holders”) upfront consideration in an aggregate amount of $ 45.0 million, excluding customary purchase price adjustments and closing costs, payable in cash. Pursuant to the Rewrite Merger Agreement, the Company acquired all of the issued and outstanding shares of Rewrite. The Rewrite transaction resulted in the acquisition of certain know-how and IP assets related to Rewrite’s proprietary DNA writing technology. The Company ’s management determined that the acquired assets do not meet the definition of a business pursuant to ASC 805, Business Combinations , as substantially all of the fair value of the acquired assets is concentrated into one identifiable asset, the DNA writing technology. As of the date of closing of the transactions contemplated by the Rewrite Merger Agreement (the “Rewrite Merger Agreement Date”), the asset acquired had no alternative future use and had not reached a stage of technological feasibility. As a result, all payment obligations were recorded as research and development expense in the condensed consolidated statements of operations and other comprehensive loss in the amount of $ 56.0 million. The total transaction price was allocated to the assets acquired and liabilities assumed on a relative fair value basis. In addition, the Rewrite Holders are eligible to receive up to an additional $ 155.0 million, including $ 55.0 million upon the achievement of pre-specified research milestones and $ 100.0 million upon the achievement of a regulatory approval milestone, payable through a mixture of $ 130.0 million in cash and $ 25.0 million in a combination of cash and the Company’s common stock which would be valued using the volume-weighted average price of the Company’s Common Stock over the ten consecutive trading day period ending on and including the trading day that is two trading days immediately prior to the issuance of the consideration issued in connection with the applicable milestone. In September 2022, Rewrite Therapeutics, Inc. merged into Intellia, with Intellia the surviving entity. In January 2023, the $ 25.0 million research milestone noted above was achieved and, in February 2023, the Company paid the Rewrite Holders $ 0.9 million in cash and issued 567,045 shares of Intellia common stock in order to fulfill its obligation under the Rewrite Merger Agreement. The cash obligation was recorded as research and development expense in the condensed consolidated statement of operations and other comprehensive loss in the first quarter of 2023. The Company had determined that the research milestone settled in the Company’s common stock would be classified as a contingent consideration liability under ASC 480 and, therefore, the Company initially recorded a liability for this milestone payment as of the Rewrite Merger Agreement Date at its original fair value of $ 10.5 million. The contingent consideration liability was remeasured at fair value each financial reporting period, with the resulting impact reflected in the Company’s condensed consolidated statements of operations and other comprehensive loss, presented within other income (expense). The remaining milestones to be settled in cash would be recorded when the contingency is resolved and the consideration is paid or becomes payable. The transaction price on the Rewrite Merger Agreement Date was determined and allocated as follows (in thousands): Transaction Price Upfront cash consideration $ 43,730 Research contingent consideration liabilities 10,541 Transaction costs 1,838 Total transaction price $ 56,109 Transaction Price Allocated In-process research and development $ 55,990 Cash acquired 287 Other current assets acquired 153 Other liabilities assumed ( 321 ) Total transaction price $ 56,109

Leases

Leases	9 Months Ended
	Sep. 30, 2023
Leases [Abstract]
Leases	10. Leases In January 2023, the Company performed a remeasurement of their lease for office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts, as the Company’s rentable square footage had been modified. This remeasurement included an update to the incremental borrowing rate from 7.99 % to 8.4 %, and resulted in a decrease in the right of use asset and lease liability of $ 0.2 million. Also in January 2023, the Company executed a sublease for a portion of their leased office and laboratory space at 730 Main Street, Cambridge, Massachusetts. In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”), which will provide the Company with the ability to manufacture its own products in a good manufacturing practice (“GMP”) compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The 840 Winter Lease, including the obligation to pay rent, is expected to commence in 2024 for an initial term of twelve years . The base rent under the 840 Winter Lease is $ 73.50 per square foot per year during the first year of the term, which is subject to scheduled 3 % annual increases, plus certain operating expenses and taxes. The Company has the option to extend the 840 Winter Lease for two five-year terms. In June 2023, the Company executed an amendment to the 840 Winter Lease, which outlines the Company’s and the landlord’s responsibilities regarding the construction of the leased space. The Company will be responsible for the oversight of the construction of the tenant improvements, which will be primarily funded by a tenant improvement allowance of $ 250 per rentable square foot. The Company has elected an additional tenant improvement allowance of $ 50 per rentable square foot to be repaid over the term of the lease with interest, with an option to increase the allowance by an additional $ 100 per rentable square foot which would also be repaid over the term of the lease with interest. The Company will also be responsible for certain future construction costs to the extent that they exceed the tenant improvement allowance. The Company anticipates a phased move-in process during the second half of 2024. As of September 30, 2023, the Company had not taken control of the premises and therefore there are no right of use assets or liabilities recorded related to the 840 Winter Lease under ASC 842, Leases (Topic 842) (“ASC 842”).

Equity-Based Compensation

Equity-Based Compensation	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Equity-Based Compensation	11. Equity-Based Compensation Equity-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (In thousands) Research and development $ 21,235 $ 16,383 $ 60,517 $ 40,736 General and administrative 14,117 8,832 38,490 26,038 Total $ 35,352 $ 25,215 $ 99,007 $ 66,774 Amended and Restated 2015 Stock Option and Incentive Plan In April 2016, the Company adopted the Amended and Restated 2015 Stock Option and Incentive Plan (the “2015 Plan”). The 2015 Plan provides for the grant of incentive stock options, non-qualified stock options, stock appreciation rights, restricted stock awards (“RSAs”), restricted stock units (“RSUs”) and other stock-based awards. Recipients of incentive stock options and non-qualified stock options are eligible to purchase shares of the Company’s common stock at an exercise price equal to the fair value of such stock on the grant date. The Company maintains a retirement policy for equity awards granted to all employees (the “Retirement Policy”), which applies to all equity awards granted after July 1, 2022 to employees who meet certain retirement eligibility criteria set forth in the Retirement Policy (the “Retirees”). Pursuant to the terms of the Retirement Policy, upon a Retiree’s eligible retirement: (i) all stock options held by the Retiree will continue to vest following the Retiree’s retirement date according to the original vesting schedule of the option until fully vested and all vested stock options held by such Retiree will remain exercisable until the earlier of the five-year anniversary of the Retiree’s retirement date or the original expiration date of the option, (ii) all unvested time-based RSUs held by the Retiree will vest in full on the Retiree’s retirement date and (iii) all unvested performance-based awards held by the Retiree will remain outstanding following the Retiree’s retirement date and the Retiree will remain eligible to earn a pro-rated portion of such performance-based awards at the end of the performance period based on actual performance during the performance period. As of September 30, 2023 , there were 4,005,307 shares available for future issuance under the 2015 Plan. The number of shares reserved for issuance under the 2015 Plan will be cumulatively increased on each January 1 st by four percent of the number of shares of stock issued and outstanding on the immediately preceding December 31 st or such lesser number of shares of stock as determined by the board of directors. Restricted Stock Units The following table summarizes the Company’s RSU activity for the nine months ended September 30, 2023: Number of Weighted Unvested restricted stock units as of December 31, 2022 1,941,379 $ 70.70 Granted 2,774,271 42.36 Vested ( 597,610 ) 68.31 Cancelled ( 193,503 ) 49.70 Unvested restricted stock units as of September 30, 2023 3,924,537 $ 52.07 In March 2023, the Company granted 2,195,135 RSUs with a service condition to employees as part of their annual grant, which have the potential to vest over a period of three years . The weighted average grant date fair value of these RSUs was $ 40.75 and the vesting start date for these RSUs was January 1, 2023. Also in March 2023, 181,743 market-based RSUs were granted to senior executives as part of their annual grant . These RSUs have the potential to vest after a period of three years , with a vesting start date of January 1, 2023, and the number of shares to be delivered will depend on the Company ’s Total Shareholder Return (“TSR” ), a market condition, over that period relative to a defined group of biotechnology companies. The grant date fair value for these RSUs, calculated using a Monte Carlo valuation model, was $ 68.55 . The following assumptions were used to determine the grant date fair value: risk free interest rate: 4.60 %; expected dividend yield: 0.0 %; expected volatility: 84.34 %; expected term (in years): 2.84 . In March 2022, the Company granted 66,296 performance-based RSUs to certain non-executive employees that would vest upon obtaining certain scientific milestones. There were two separate tranches, each attached to a different set of milestones. The milestone related to the first tranche, made up of 21,878 RSUs, was achieved in the first quarter of 2023 and these RSUs vested. The remaining performance milestones were considered not probable of achievement as of September 30, 2023 and, therefore, no related stock-based compensation was recorded during the period then ending. All RSUs that are not market-based are measured at fair value based on the quoted price of the Company’s common stock. The weighted-average grant date fair value of RSUs granted during the three and nine months ended September 30, 2023 was $ 39.14 and $ 42.36 , respectively. The total fair value of RSUs vested (measured on the date of vesting) for the three and nine months ended September 30, 2023 was $ 4.2 million and $ 22.5 million, respectively. The weighted-average grant date fair value of RSUs granted during the three and nine months ended September 30, 2022 was $ 55.59 and $ 72.48 , respectively. The total fair value of RSUs vested (measured on the date of vesting) for the three and nine months ended September 30, 2022 was $ 0.1 million and $ 8.0 million, respectively. As of September 30, 2023 , there was $ 143.2 million of unrecognized equity-based compensation expense related to RSUs that are expected to vest; these costs are expected to be recognized over a weighted average remaining vesting period of 1.86 years . Stock Options The weighted average grant date fair value of options, estimated as of the grant date using the Black-Scholes option pricing model, was $ 28.92 and $ 57.23 per option for those options granted during the nine months ended September 30, 2023 and 2022 , respectively. There were no options granted during the three months ended September 30, 2023 and 2022. The total intrinsic value (the amount by which the fair market value exceeded the exercise price) of stock options exercised during the three and nine months ended September 30, 2023 was $ 4.8 million and $ 6.6 million, respectively, and during the three and nine months ended September 30, 2022 was $ 1.4 million and $ 41.8 million, respectively . Weighted average assumptions used to apply this pricing model were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate n/a n/a 4.4 % 1.9 % Expected life of options n/a n/a 6.0 years 5.9 years Expected volatility of underlying stock n/a n/a 78.7 % 76.2 % Expected dividend yield n/a n/a 0.0 % 0.0 % Risk-free Interest Rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant with maturities approximately equal to the option’s expected term. Expected Term. The expected term represents the period that stock option awards are expected to be outstanding. For option grants that are considered to be “plain vanilla,” the Company determines the expected term using the simplified method. The simplified method deems the term to be the average of the time-to-vesting and the contractual life of the options. The Company uses the simplified method because it does not have sufficient historical option exercise data to provide a reasonable basis upon which to estimate the expected term. Expected Volatility. The expected volatility was derived from a blend of the Company’s historical volatility and an average of the historical stock volatilities of several peer companies within the Company’s industry, both over a period equivalent to the expected term of the stock option grants. Expected Dividend Yield. The expected dividend yield assumption is based on the fact that the Company has never paid cash dividends and has no present intention to pay cash dividends. Stock options granted under the 2015 Plan in 2023 generally vest as to one-third on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining two years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years. The Company uses the market closing price of its common stock as reported on the Nasdaq Global Select Market to determine the fair value of the shares of common stock underlying stock options. The following is a summary of stock option activity for the nine months ended September 30, 2023: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2022 5,471,675 $ 49.86 Granted 569,821 41.00 Exercised ( 319,847 ) 17.52 Forfeited ( 130,474 ) 80.20 Outstanding at September 30, 2023 5,591,175 $ 50.10 6.87 $ 39,821 Exercisable at September 30, 2023 3,846,015 $ 42.52 6.30 $ 36,370 As of September 30, 2023 , there was $ 69.2 million of unrecognized compensation cost related to stock options that have not yet vested; these costs are expected to be recognized over a weighted average remaining vesting period of 1.63 years. 2016 Employee Stock Purchase Plan In May 2016, the Company adopted the 2016 Employee Stock Purchase Plan (the “2016 Plan”). The 2016 Plan allows eligible employees to purchase shares of the Company’s common stock on the last day of each predetermined six-month offering period at 85 % of the lower of the fair market value per share at the beginning or end of the applicable offering period. The 2016 Plan provides for six-month offering periods beginning in January and July of each year. As of September 30, 2023 , there were 1,149,953 shares available for future issuance under the 2016 Plan. The number of shares reserved for issuance under the 2016 Plan will be cumulatively increased on each January 1 st by the lesser of a) one percent of the number of shares of common stock issued and outstanding on the immediately preceding December 31 st , b) 500,000 shares of common stock, or c) such lesser number of shares of common stock as determined by the board of directors. During the nine months ended September 30, 2023 and 2022 the Company issued 69,631 and 24,316 shares of common stock under the 2016 Plan, respectively. The weighted-average purchase prices of shares issued under the 2016 Plan were $ 29.45 and $ 44.00 per share for the nine-month periods ended September 30, 2023 and 2022, respectively. The fair value of shares under the 2016 Plan was estimated at the beginning of the offering period using a Black-Scholes option-pricing model with the following assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate 5.53 % 2.52 % 4.7 %- 5.53 % 0.22 %- 2.52 % Expected term (in years) 0.5 years 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 60.4 % 95.3 % 60.4 %- 69.2 % 63.6 %- 95.3 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 %

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Loss Per Share	12. Loss Per Share The Company calculates basic loss per share by dividing net loss for each respective period by the weighted average number of common shares outstanding for each respective period. The Company computes diluted loss per share after giving consideration to the dilutive effect of stock options and unvested restricted stock units that are outstanding during the period, except where such securities would be anti-dilutive. Basic and diluted loss per share was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (In thousands) Net loss $ ( 122,224 ) $ ( 113,229 ) $ ( 349,031 ) $ ( 360,779 ) Weighted average shares outstanding, basic 88,645 76,047 88,204 75,543 Net loss per share, basic and diluted $ ( 1.38 ) $ ( 1.49 ) $ ( 3.96 ) $ ( 4.78 ) The following common stock equivalents were excluded from the calculation of diluted loss per share because their inclusion would have been anti-dilutive: Three and Nine Months Ended September 30, 2023 2022 (In thousands) Unvested restricted stock units 3,925 1,928 Stock options 5,591 5,548 9,516 7,476

Stockholders_ Equity

Stockholders’ Equity	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Stockholders’ Equity	13. Stockholders’ Equity The following tables present changes in stockholders’ equity for the nine-month periods ended September 30, 2023 and 2022 (in thousands, except share data): Additional Accumulated Other Total Common Paid-In Comprehensive Accumulated Stockholders’ Shares Amount Capital Loss Deficit Equity Balance at December 31, 2022 87,103,007 $ 9 $ 2,420,223 $ ( 7,461 ) $ ( 1,177,187 ) $ 1,235,584 Issuance of common stock through 62 35,349 - 1,466 - - 1,466 Contingent consideration paid to Rewrite Holders 567,045 - 24,126 - - 24,126 Exercise of stock options 48,353 - 755 - - 755 Vesting of restricted stock units 342,025 - - - - - Equity-based compensation - - 27,255 - - 27,255 Other comprehensive loss - unrealized gain on - - - 2,989 - 2,989 Other comprehensive loss - equity method - - - 1,794 - 1,794 Net loss - - - ( 103,126 ) ( 103,126 ) Balance at March 31, 2023 88,095,779 9 2,473,825 ( 2,678 ) ( 1,280,313 ) 1,190,843 Exercise of stock options 30,371 - 465 - - 465 Vesting of restricted stock units 151,853 - - - - - Issuance of shares under employee 69,631 - 2,051 - - 2,051 Equity-based compensation - - 36,400 - - 36,400 Other comprehensive loss - unrealized loss on - - - ( 1,482 ) - ( 1,482 ) Other comprehensive loss - equity method - - - 292 - 292 Net loss - - - - ( 123,681 ) ( 123,681 ) Balance at June 30, 2023 88,347,634 9 2,512,741 ( 3,868 ) ( 1,403,994 ) 1,104,888 Issuance of common stock through 81 405,332 - 14,718 - - 14,718 Exercise of stock options 241,123 - 4,384 - - 4,384 Vesting of restricted stock units 103,732 - - - - - Equity-based compensation - - 35,352 - - 35,352 Other comprehensive loss - unrealized gain on marketable securities - - - 142 - 142 Other comprehensive loss - equity method investment - - - 154 - 154 Net loss - - - - ( 122,224 ) ( 122,224 ) Balance at September 30, 2023 89,097,821 $ 9 $ 2,567,195 $ ( 3,572 ) $ ( 1,526,218 ) $ 1,037,414 Additional Accumulated Other Total Common Paid-In Comprehensive Accumulated Stockholders’ Shares Amount Capital Loss Deficit Equity Balance at December 31, 2021 74,485,883 $ 7 $ 1,745,870 $ ( 2,632 ) $ ( 703,001 ) $ 1,040,244 Issuance of common stock through 164 579,788 1 38,885 - - 38,886 Exercise of stock options 503,830 - 8,435 - - 8,435 Vesting of restricted stock units 54,666 - - - - - Equity-based compensation - - 18,491 - - 18,491 Other comprehensive loss - unrealized loss on - - - ( 5,128 ) - ( 5,128 ) Other comprehensive loss - equity method - - - ( 302 ) - ( 302 ) Net loss - - - - ( 146,872 ) ( 146,872 ) Balance at March 31, 2022 75,624,167 8 1,811,681 ( 8,062 ) ( 849,873 ) 953,754 Exercise of stock options 315,747 - 4,827 - - 4,827 Vesting of restricted stock units 36,515 - - - - - Issuance of shares under employee 24,316 - 1,068 - - 1,068 Equity-based compensation - - 23,068 - - 23,068 Other comprehensive loss - unrealized loss on - - - ( 932 ) - ( 932 ) Other comprehensive loss - equity method - - - ( 560 ) - ( 560 ) Net loss - - - - ( 100,678 ) ( 100,678 ) Balance at June 30, 2022 76,000,745 8 1,840,644 ( 9,554 ) ( 950,551 ) 880,547 Issuance of common stock through 54 553,204 - 31,510 - - 31,510 Exercise of stock options 33,336 - 722 - - 722 Vesting of restricted stock units 662 - - - - - Equity-based compensation - - 25,215 - - 25,215 Other comprehensive loss - unrealized gain on marketable securities - - - 991 - 991 Other comprehensive loss - equity method investment - - - ( 805 ) - ( 805 ) Net loss - - - - ( 113,229 ) ( 113,229 ) Balance at September 30, 2022 76,587,947 $ 8 $ 1,898,091 $ ( 9,368 ) $ ( 1,063,780 ) $ 824,951 At-the-Market Offering Programs 2019 Sale Agreement In August 2019, the Company entered into an Open Market Sale Agreement (the “2019 Sale Agreement”) with Jefferies LLC (“Jefferies”), under which Jefferies was able to offer and sell, from time to time in “at-the-market” offerings, common stock having aggregate gross proceeds of up to $ 150.0 million. The Company agreed to pay Jefferies cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2019 Sale Agreement. Under the 2019 Sale Agreement, the Company issued 3,778,889 shares of its common stock. During the first quarter of 2022, the Company issued 579,788 shares of its common stock, in a series of sales, at an average price of $ 69.43 per share, in accordance with the 2019 Sale Agreement for aggregate net proceeds of $ 38.9 million, after payment of cash commissions to Jefferies and approximately $ 0.2 million related to legal, accounting and other fees in connection with the sales. The 2019 Sale Agreement expired in the third quarter of 2022. 2022 Sale Agreement In March 2022, the Company entered into an Open Market Sale Agreement (the “2022 Sale Agreement”) with Jefferies, under which Jefferies is able to offer and sell, from time to time in “at-the-market” offerings, shares of the Company’ s common stock having aggregate gross proceeds of up to $ 400.0 million. The Company agreed to pay Jefferies cash commissions of 3.0 % of the gross proceeds of sales of common stock under the 2022 Sale Agreement. Through September 30, 2023, the Company issued 3,836,020 shares of its common stock under the 2022 Sale Agreement. During the nine months ended September 30, 2023 , the Company issued 440,681 shares of its common stock, in a series of sales, at an average price of $ 38.20 per share, in accordance with the 2022 Sale Agreement for aggregate net proceeds of $ 16.2 million, after payment of cash commissions to Jefferies and approximately $ 0.1 million related to legal, accounting and other fees in connection with the sales. During the nine months ended September 30, 2022, the Company issued 553,204 shares of its common stock, in a series of sales, at an average price of $ 58.82 per share, in accordance with the 2022 Sale Agreement for aggregate net proceeds of $ 31.5 million, after payment of cash commissions to Jefferies and approximately $ 0.1 million related to legal, accounting and other fees in connection with the sales. As of September 30, 2022, $ 8.3 million of these proceeds were recorded as an other current asset on the Company’s condensed consolidated balance sheet, representing offerings with trade dates in September 2022 that were settled in October 2022. As of September 30, 2023 , $ 188.2 million in shares of common stock remain eligible for sale under the 2022 Sale Agreement. Approval of Additional Authorized Shares In June 2023, the Company filed a Certificate of Amendment to the Company’s Second Amended and Restated Certificate of Incorporation to increase the number of authorized shares of common stock from 120,000,000 to 240,000,000 . The increase in the number of authorized shares was approved by the holders of a majority of the outstanding shares of the Company’s common stock at its Annual Meeting of Stockholders held on June 14, 2023.

Related Party Transactions

Related Party Transactions	9 Months Ended
	Sep. 30, 2023
Related Party Transactions [Abstract]
Related Party Transactions	14. Related Party Transactions In the ordinary course of business, the Company may purchase materials or supplies from entities that are associated with a party that meets the criteria of a related party of the Company. These transactions are reviewed quarterly and to date have not been material to the Company’s condensed consolidated financial statements. The Company and AvenCell are parties to the AvenCell LCA and AvenCell Co/Co, as described in Note 7. The Company’s relationship with AvenCell is considered to be as a related party due to the Company’s 33.33 % investment in AvenCell being accounted for under the equity method. The Company recognized $ 1.9 million and $ 13.2 million in revenue related to the AvenCell LCA for the three and nine months ended September 30, 2023 , respectively, after eliminating $ 1.0 million and $ 6.6 million during those respective periods in intra-entity profits, which will be deferred and recognized if and when AvenCell commercializes a product with the Company ’ s license or abandons the related project. Until such time, this revenue is indefinitely deferred and excluded from the results of operations of the Company. The Company recognized no revenue in the three months ended September 30, 2023 and $ 0.6 million in contra-revenue in the nine months ended September 30, 2023 related to the AvenCell Co/Co agreement. The Company recognized $ 1.3 million in revenue and $ 1.4 million in contra-revenue in the three and nine months ended September 30, 2022, respectively, related to the AvenCell Co/Co agreement. As of September 30, 2023 the Company had recognized all revenue related to the AvenCell LCA.

Marketable Securities (Tables)

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2023
Investments, Debt and Equity Securities [Abstract]
Summary of Available-for-sale Marketable Securities	The following table summarizes the Company’s available-for-sale marketable securities as of September 30, 2023 and December 31, 2022 at net book value: September 30, 2023 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 330,875 $ 3 $ ( 935 ) $ 329,943 Financial institution debt securities 319,226 40 ( 688 ) 318,578 Corporate debt securities 115,344 4 ( 306 ) 115,042 Other asset-backed securities 61,188 - ( 238 ) 60,950 Total $ 826,633 $ 47 $ ( 2,167 ) $ 824,513 December 31, 2022 Amortized Gross Unrealized Gross Unrealized Estimated Fair (In thousands) Marketable securities: U.S. Treasury and other government-backed securities $ 244,562 $ 62 $ ( 1,938 ) $ 242,686 Financial institution debt securities 380,891 - ( 1,030 ) 379,861 Corporate debt securities 102,059 - ( 509 ) 101,550 Other asset-backed securities 14,703 - ( 346 ) 14,357 Total $ 742,215 $ 62 $ ( 3,823 ) $ 738,454

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	9 Months Ended
	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Summary of Financial Assets Recognized at Fair Value on Recurring Basis	As of September 30, 2023 and December 31, 2022, the Company’s financial assets recognized at fair value on a recurring basis consisted of the following: Fair Value as of September 30, 2023 Total Level 1 Level 2 Level 3 (In thousands) Assets Cash equivalents and restricted cash equivalents $ 139,880 $ 139,880 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 329,943 77,781 252,162 - Financial institution debt securities 318,578 - 318,578 - Corporate debt securities 115,042 - 115,042 - Other asset-backed securities 60,950 - 60,950 - Total marketable securities 824,513 77,781 746,732 - Total Assets $ 964,393 $ 217,661 $ 746,732 $ - Fair Value as of December 31, 2022 Total Level 1 Level 2 Level 3 (In thousands) Assets Cash equivalents and restricted cash equivalents $ 534,581 $ 534,581 $ - $ - Marketable securities: U.S. Treasury and other government-backed securities 242,686 172,939 69,747 - Financial institution debt securities 379,861 - 379,861 - Corporate debt securities 101,550 - 101,550 - Other asset-backed securities 14,357 - 14,357 - Total marketable securities 738,454 172,939 565,515 - Total Assets $ 1,273,035 $ 707,520 $ 565,515 $ -
Schedule of Change in Fair Value of the Contingent Consideration Liabilities	The following table reconciles the change in fair value of the contingent consideration liability based on the level 3 inputs listed below (in thousands): For the Nine Months Balance at December 31, 2022 $ 24,026 Change in fair value 100 Payment of contingent consideration ( 24,126 ) Balance at September 30, 2023 $ - December 31, 2022 Discount rate 10.1 % Probability of achievement 100 % Projected year of achievement 2023

Accrued Expenses (Tables)

Accrued Expenses (Tables)	9 Months Ended
	Sep. 30, 2023
Payables and Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following: September 30, December 31, 2023 2022 (In thousands) Accrued research and development $ 24,241 $ 32,684 Employee compensation and benefits 21,006 21,778 Accrued legal and professional expenses 1,649 1,457 Accrued other 11,083 4,957 Total accrued expenses $ 57,979 $ 60,876

Collaborations and Other Arra_2

Collaborations and Other Arrangements (Tables)	9 Months Ended
	Sep. 30, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of Changes in Accounts Receivable and Contract Liabilities	The following table presents changes in the Company’s accounts receivable and contract liabilities during the nine months ended September 30, 2023 and 2022 (in thousands): Balance at Additions Deductions Balance at End Nine Months Ended September 30, 2023 Accounts receivable $ 3,768 $ 15,287 $ ( 12,564 ) $ 6,491 Contract liabilities - deferred revenue $ 63,771 $ - $ ( 37,705 ) $ 26,066 Balance at Additions Deductions Balance at End Nine Months Ended September 30, 2022 Accounts receivable $ 2,031 $ 8,678 $ ( 6,686 ) $ 4,023 Contract liabilities - deferred revenue $ 127,235 $ - $ ( 46,739 ) $ 80,496
Summary of Revenues Recognized Resulting from Changes in Contract Liability Balance	During the nine months ended September 30, 2023 and 2022, the Company recognized the following revenues as a result of changes in the contract liability balance (in thousands): Nine Months Ended September 30, Revenue recognized in the period from: 2023 2022 Amounts included in the contract liability at the beginning of the period $ 31,081 $ 38,208

Rewrite Acquisition (Tables)

Rewrite Acquisition (Tables)	9 Months Ended
	Sep. 30, 2023
Business Combinations [Abstract]
Summary of Transaction Price on Rewrite Merger Agreement Date Determined and Allocated	The transaction price on the Rewrite Merger Agreement Date was determined and allocated as follows (in thousands): Transaction Price Upfront cash consideration $ 43,730 Research contingent consideration liabilities 10,541 Transaction costs 1,838 Total transaction price $ 56,109 Transaction Price Allocated In-process research and development $ 55,990 Cash acquired 287 Other current assets acquired 153 Other liabilities assumed ( 321 ) Total transaction price $ 56,109

Equity-Based Compensation (Tabl

Equity-Based Compensation (Tables)	9 Months Ended
	Sep. 30, 2023
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Schedule of Equity-Based Compensation Expense	Equity-based compensation expense is classified in the condensed consolidated statements of operations and comprehensive loss as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (In thousands) Research and development $ 21,235 $ 16,383 $ 60,517 $ 40,736 General and administrative 14,117 8,832 38,490 26,038 Total $ 35,352 $ 25,215 $ 99,007 $ 66,774
Summary of Restricted Stock Activity	The following table summarizes the Company’s RSU activity for the nine months ended September 30, 2023: Number of Weighted Unvested restricted stock units as of December 31, 2022 1,941,379 $ 70.70 Granted 2,774,271 42.36 Vested ( 597,610 ) 68.31 Cancelled ( 193,503 ) 49.70 Unvested restricted stock units as of September 30, 2023 3,924,537 $ 52.07
Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted	Weighted average assumptions used to apply this pricing model were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate n/a n/a 4.4 % 1.9 % Expected life of options n/a n/a 6.0 years 5.9 years Expected volatility of underlying stock n/a n/a 78.7 % 76.2 % Expected dividend yield n/a n/a 0.0 % 0.0 %
Summary of Stock Option Activity	The following is a summary of stock option activity for the nine months ended September 30, 2023: Number of Weighted Weighted Aggregate (In years) (In thousands) Outstanding at December 31, 2022 5,471,675 $ 49.86 Granted 569,821 41.00 Exercised ( 319,847 ) 17.52 Forfeited ( 130,474 ) 80.20 Outstanding at September 30, 2023 5,591,175 $ 50.10 6.87 $ 39,821 Exercisable at September 30, 2023 3,846,015 $ 42.52 6.30 $ 36,370
2016 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted	The fair value of shares under the 2016 Plan was estimated at the beginning of the offering period using a Black-Scholes option-pricing model with the following assumptions: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 Risk-free interest rate 5.53 % 2.52 % 4.7 %- 5.53 % 0.22 %- 2.52 % Expected term (in years) 0.5 years 0.5 years 0.5 years 0.5 years Expected volatility of underlying stock 60.4 % 95.3 % 60.4 %- 69.2 % 63.6 %- 95.3 % Expected dividend yield 0.0 % 0.0 % 0.0 % 0.0 %

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2023
Earnings Per Share [Abstract]
Schedule of Basic and Diluted Net Loss Per Share	Basic and diluted loss per share was calculated as follows: Three Months Ended September 30, Nine Months Ended September 30, 2023 2022 2023 2022 (In thousands) Net loss $ ( 122,224 ) $ ( 113,229 ) $ ( 349,031 ) $ ( 360,779 ) Weighted average shares outstanding, basic 88,645 76,047 88,204 75,543 Net loss per share, basic and diluted $ ( 1.38 ) $ ( 1.49 ) $ ( 3.96 ) $ ( 4.78 )
Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share	The following common stock equivalents were excluded from the calculation of diluted loss per share because their inclusion would have been anti-dilutive: Three and Nine Months Ended September 30, 2023 2022 (In thousands) Unvested restricted stock units 3,925 1,928 Stock options 5,591 5,548 9,516 7,476

Stockholders_ Equity (Tables)

Stockholders’ Equity (Tables)	9 Months Ended
	Sep. 30, 2023
Equity [Abstract]
Schedule of Changes in Stockholders’ Equity	The following tables present changes in stockholders’ equity for the nine-month periods ended September 30, 2023 and 2022 (in thousands, except share data): Additional Accumulated Other Total Common Paid-In Comprehensive Accumulated Stockholders’ Shares Amount Capital Loss Deficit Equity Balance at December 31, 2022 87,103,007 $ 9 $ 2,420,223 $ ( 7,461 ) $ ( 1,177,187 ) $ 1,235,584 Issuance of common stock through 62 35,349 - 1,466 - - 1,466 Contingent consideration paid to Rewrite Holders 567,045 - 24,126 - - 24,126 Exercise of stock options 48,353 - 755 - - 755 Vesting of restricted stock units 342,025 - - - - - Equity-based compensation - - 27,255 - - 27,255 Other comprehensive loss - unrealized gain on - - - 2,989 - 2,989 Other comprehensive loss - equity method - - - 1,794 - 1,794 Net loss - - - ( 103,126 ) ( 103,126 ) Balance at March 31, 2023 88,095,779 9 2,473,825 ( 2,678 ) ( 1,280,313 ) 1,190,843 Exercise of stock options 30,371 - 465 - - 465 Vesting of restricted stock units 151,853 - - - - - Issuance of shares under employee 69,631 - 2,051 - - 2,051 Equity-based compensation - - 36,400 - - 36,400 Other comprehensive loss - unrealized loss on - - - ( 1,482 ) - ( 1,482 ) Other comprehensive loss - equity method - - - 292 - 292 Net loss - - - - ( 123,681 ) ( 123,681 ) Balance at June 30, 2023 88,347,634 9 2,512,741 ( 3,868 ) ( 1,403,994 ) 1,104,888 Issuance of common stock through 81 405,332 - 14,718 - - 14,718 Exercise of stock options 241,123 - 4,384 - - 4,384 Vesting of restricted stock units 103,732 - - - - - Equity-based compensation - - 35,352 - - 35,352 Other comprehensive loss - unrealized gain on marketable securities - - - 142 - 142 Other comprehensive loss - equity method investment - - - 154 - 154 Net loss - - - - ( 122,224 ) ( 122,224 ) Balance at September 30, 2023 89,097,821 $ 9 $ 2,567,195 $ ( 3,572 ) $ ( 1,526,218 ) $ 1,037,414 Additional Accumulated Other Total Common Paid-In Comprehensive Accumulated Stockholders’ Shares Amount Capital Loss Deficit Equity Balance at December 31, 2021 74,485,883 $ 7 $ 1,745,870 $ ( 2,632 ) $ ( 703,001 ) $ 1,040,244 Issuance of common stock through 164 579,788 1 38,885 - - 38,886 Exercise of stock options 503,830 - 8,435 - - 8,435 Vesting of restricted stock units 54,666 - - - - - Equity-based compensation - - 18,491 - - 18,491 Other comprehensive loss - unrealized loss on - - - ( 5,128 ) - ( 5,128 ) Other comprehensive loss - equity method - - - ( 302 ) - ( 302 ) Net loss - - - - ( 146,872 ) ( 146,872 ) Balance at March 31, 2022 75,624,167 8 1,811,681 ( 8,062 ) ( 849,873 ) 953,754 Exercise of stock options 315,747 - 4,827 - - 4,827 Vesting of restricted stock units 36,515 - - - - - Issuance of shares under employee 24,316 - 1,068 - - 1,068 Equity-based compensation - - 23,068 - - 23,068 Other comprehensive loss - unrealized loss on - - - ( 932 ) - ( 932 ) Other comprehensive loss - equity method - - - ( 560 ) - ( 560 ) Net loss - - - - ( 100,678 ) ( 100,678 ) Balance at June 30, 2022 76,000,745 8 1,840,644 ( 9,554 ) ( 950,551 ) 880,547 Issuance of common stock through 54 553,204 - 31,510 - - 31,510 Exercise of stock options 33,336 - 722 - - 722 Vesting of restricted stock units 662 - - - - - Equity-based compensation - - 25,215 - - 25,215 Other comprehensive loss - unrealized gain on marketable securities - - - 991 - 991 Other comprehensive loss - equity method investment - - - ( 805 ) - ( 805 ) Net loss - - - - ( 113,229 ) ( 113,229 ) Balance at September 30, 2022 76,587,947 $ 8 $ 1,898,091 $ ( 9,368 ) $ ( 1,063,780 ) $ 824,951

Overview and Basis of Present_2

Overview and Basis of Presentation - Additional Information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
IPO [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering	$ 2,424.1

Marketable Securities - Summary

Marketable Securities - Summary of Available -for-sale Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Amortized Cost	$ 826,633	$ 742,215
Gross Unrealized Gains	47	62
Gross Unrealized Losses	(2,167)	(3,823)
Estimated Fair Value	824,513	738,454
U.S. Treasury and Other Government - Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	330,875	244,562
Gross Unrealized Gains	3	62
Gross Unrealized Losses	(935)	(1,938)
Estimated Fair Value	329,943	242,686
Financial Institution Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	319,226	380,891
Gross Unrealized Gains	40	0
Gross Unrealized Losses	(688)	(1,030)
Estimated Fair Value	318,578	379,861
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	115,344	102,059
Gross Unrealized Gains	4	0
Gross Unrealized Losses	(306)	(509)
Estimated Fair Value	115,042	101,550
Other Asset Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	61,188	14,703
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(238)	(346)
Estimated Fair Value	$ 60,950	$ 14,357

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Marketable Securities [Line Items]
Realized gains or losses on marketable securities	$ 0	$ 0
Minimum
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	1 year
Maximum
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	5 years

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Financial Assets Recognized at Fair Value on Recurring Basis (Detail) - Fair Value on Recurring Basis [Member] - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Assets
Cash equivalents and restricted cash equivalents	$ 139,880	$ 534,581
Marketable securities:
Marketable securities	824,513	738,454
Total Assets	964,393	1,273,035
U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	329,943	242,686
Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	318,578	379,861
Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	115,042	101,550
Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	60,950	14,357
Level 1 [Member]
Assets
Cash equivalents and restricted cash equivalents	139,880	534,581
Marketable securities:
Marketable securities	77,781	172,939
Total Assets	217,661	707,520
Level 1 [Member] | U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	77,781	172,939
Level 2 [Member]
Marketable securities:
Marketable securities	746,732	565,515
Total Assets	746,732	565,515
Level 2 [Member] | U.S. Treasury and Other Government - Backed Securities [Member]
Marketable securities:
Marketable securities	252,162	69,747
Level 2 [Member] | Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	318,578	379,861
Level 2 [Member] | Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	115,042	101,550
Level 2 [Member] | Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	$ 60,950	$ 14,357

Fair Value Measurements - Addit

Fair Value Measurements - Additional information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2023 USD ($)
Cash and Cash Equivalents [Line Items]
Research milestone payments	$ 25
Cash
Cash and Cash Equivalents [Line Items]
Research milestone payments	$ 0.9

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Change in Fair Value of the Contingent Consideration Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Balance	$ 24,026
Change in fair value	100
Payment of contingent consideration	(24,126)
Balance	$ 0	$ 24,026
Discount rate		10.10%
Probability of achievement		100%
Projected year of achievement		2023

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued research and development	$ 24,241	$ 32,684
Employee compensation and benefits	21,006	21,778
Accrued legal and professional expenses	1,649	1,457
Accrued other	11,083	4,957
Total accrued expenses	$ 57,979	$ 60,876

Collaborations and Other Arra_3

Collaborations and Other Arrangements - Summary of Changes in Accounts Receivable and Contract Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Accounts receivable:
Accounts receivable, Balance at Beginning of Period	$ 3,768	$ 2,031
Accounts receivable, Additions	15,287	8,678
Accounts receivable, Deductions	(12,564)	(6,686)
Accounts receivable, Balance at End of Period	6,491	4,023
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	63,771	127,235
Deferred revenue, Deductions	(37,705)	(46,739)
Deferred revenue, Balance at End of Period	$ 26,066	$ 80,496

Collaborations and Other Arra_4

Collaborations and Other Arrangements - Summary of Revenues Recognized Resulting from Changes in Contract Liability Balance (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Revenue from Contract with Customer [Abstract]
Amounts included in the contract liability at the beginning of the period	$ 31,081	$ 38,208

Collaborations and Other Arra_5

Collaborations and Other Arrangements - Additional Information (Detail)	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	90 Months Ended
	Oct. 31, 2023 USD ($) Targetcap Product	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill contract capitalized			$ 0		$ 0			$ 0
Collaboration revenue			11,992,000	$ 13,266,000	38,192,000	$ 38,548,000
Deferred revenue			26,066,000	80,496,000	26,066,000	80,496,000	$ 63,771,000	26,066,000	$ 127,235,000
Collaboration agreement payment made					56,109,000
Revenue			1,000,000		6,600,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized			12,000,000		12,000,000			12,000,000
Deferred revenue			12,000,000		12,000,000		28,800,000	12,000,000
Regeneron Pharmaceuticals Inc. [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			5,500,000		5,500,000		3,200,000	5,500,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			1,800,000	3,200,000	7,600,000	6,900,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions					145,000,000
Collaboration revenue			9,300,000	6,500,000	$ 23,500,000	18,600,000		196,500,000
Aggregate transaction price remaining to be recognized, period					Through September 30, 2023
Payments due			5,500,000	4,000,000	$ 14,200,000	8,700,000
Deferred revenue	$ 30,000,000
Collaboration agreement extension period	two years
Additional regeneron target cap | Targetcap	5
Number of unique ex vivo products commercialized | Product	10
Collaboration term extension period	2026-04
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member] | Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue					46,100,000
ONK Therapeutics [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			200,000		200,000		100,000	200,000
ONK Therapeutics [Member] | Research Materials Shippmet Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			200,000	0	200,000	0
Kyverna Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue							400,000
Revenue		$ 400,000	100,000	2,300,000	100,000	4,300,000
Kyverna Therapeutics Inc [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			100,000		100,000		0	100,000
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			400,000	0	1,300,000	0
Deferred revenue			14,100,000		14,100,000		14,700,000	14,100,000
Sparing Vision [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			700,000		700,000		100,000	700,000
AvenCell [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions			1,000,000		6,600,000
Collaboration revenue			1,900,000		13,200,000
Deferred revenue			0		0		19,900,000	0
Revenue			1,900,000		13,200,000
AvenCell [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			9,000		9,000		300,000	$ 9,000
AvenCell [Member] | AvenCell Co Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 0	$ 1,300,000	$ 600,000	$ 1,400,000
AvenCell [Member] | Co-Development and Co-Funding Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement payment made							$ 30,000,000

Equity-Method Investment and _2

Equity-Method Investment and Other Investments - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022	Jul. 30, 2021
Schedule of Equity Method Investments [Line Items]
Loss from equity method investment		$ (3,857)	$ (1,834)	$ (10,905)	$ (7,831)
Equity method investment		17,166		17,166		$ 32,455
Preferred Stock Purchase Agreement [Member] | Joint Venture AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage							33.33%
Preferred Stock Purchase Agreement [Member] | Cellex and BXLS [Member] | Joint Venture AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Equity Method Investment, Ownership Percentage							66.67%
AvenCell [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, at Fair Value							$ 62,900
Investments in and Advances to Affiliates, at Fair Value, Gross Reductions		3,700		8,700
Loss from equity method investment		1,000		6,600
Equity method investment		17,200		17,200
Sparing Vision [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, at Fair Value	$ 14,800
Sparing Vision [Member] | Series A2 Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	83,316
Kyverna Therapeutics Inc [Member]
Schedule of Equity Method Investments [Line Items]
Investment Owned, at Fair Value		$ 10,000		$ 10,000
Kyverna Therapeutics Inc [Member] | Series B Preferred Stock [Member]
Schedule of Equity Method Investments [Line Items]
Sale of Stock, Number of Shares Issued in Transaction				3,739,515
Fair value of stock received				$ 7,000
Number of stock additionally invested				1,602,649
Cash consideration received on sale of common stock				$ 3,000

Rewrite Acquisition - Additiona

Rewrite Acquisition - Additional Information (Detail) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Feb. 02, 2022	Jan. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Feb. 28, 2023	Dec. 31, 2022
Business Acquisition [Line Items]
Research and development			$ 113,696	$ 96,651	$ 326,088	$ 319,945
Common stock, shares issued			89,097,821		89,097,821			87,103,007
Rewrite Therapeutics Delaware Corporation Member
Business Acquisition [Line Items]
Upfront consideration payable in cash	$ 45,000
Research and development	56,000
Milestone payments	155,000
Cash	$ 130,000
Common stock, shares issued	25,000,000
Liability for milestone payment	$ 10,500	$ 25,000
Rewrite Therapeutics Delaware Corporation Member | Pre-specified Research Milestones [Member]
Business Acquisition [Line Items]
Milestone payments	55,000
Rewrite Therapeutics Delaware Corporation Member | Regulatory Approval Milestone [Member]
Business Acquisition [Line Items]
Milestone payments	$ 100,000
Rewrite Therapeutics Delaware Corporation Member | Rewrite Acquisition [Member]
Business Acquisition [Line Items]
Cash							$ 900
Common stock, shares issued in connection with research milestone		567,045

Rewrite Acquisition - Summary o

Rewrite Acquisition - Summary of Transaction Price Determined and Allocated (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2023 USD ($)
Transaction Price
Upfront cash consideration	$ 43,730
Research contingent consideration liabilities	10,541
Transaction costs	1,838
Total transaction price	56,109
Transaction Price Allocated
In-process research and development	55,990
Cash acquired	287
Other current assets acquired	153
Other liabilities assumed	(321)
Total transaction price	$ 56,109

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands		1 Months Ended	6 Months Ended	9 Months Ended
	Feb. 28, 2022 ft²	Feb. 28, 2022 ft²	Jun. 30, 2023	Sep. 30, 2023 USD ($) USD_per_sqft	Dec. 31, 2022 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets | $				$ 118,775	$ 133,076
Albany Lease [Member]
Lessee Lease Description [Line Items]
Operating lease, existence of option to extend			true
840 Winter Street Lease [Member]
Lessee Lease Description [Line Items]
Area of space leased | ft²	140,000
Operating lease, description				In February 2022, the Company entered into an agreement to lease approximately 140,000 square feet of manufacturing space located at 840 Winter Street, Waltham, Massachusetts (the “840 Winter Lease”), which will provide the Company with the ability to manufacture its own products in a good manufacturing practice (“GMP”) compliant facility as well as to supplement the Company’s current leased premises in Cambridge, Massachusetts. The 840 Winter Lease, including the obligation to pay rent, is expected to commence in 2024 for an
Term of lease	12 years	12 years
Base rent per square foot for first year | ft²		73.5
Operating lease, options to extend				The Company has the option to extend the 840 Winter Lease for two five-year terms.
Percentage of Annual Increase				3%
Tenant improvement allowance per rentable square foot				250
Additional tenant improvement allowance per rentable square foot				50
Increase in tenant improvement allowance per rentable square foot				100
MemorialDrive640Member
Lessee Lease Description [Line Items]
Operating lease, description				In January 2023, the Company performed a remeasurement of their lease for office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts, as the Company’s rentable square footage had been modified. This remeasurement included an update to the incremental borrowing rate from 7.99% to 8.4%, and resulted in a decrease in the right of use asset and lease liability of $0.2 million.
Operating lease right-of-use assets | $				$ 200
Maximum
Lessee Lease Description [Line Items]
Incremental borrowing rate				8.40%
Minimum
Lessee Lease Description [Line Items]
Incremental borrowing rate				7.99%

Equity-Based Compensation - Sch

Equity-Based Compensation - Schedule of Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 35,352	$ 25,215	$ 99,007	$ 66,774
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	21,235	16,383	60,517	40,736
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 14,117	$ 8,832	$ 38,490	$ 26,038

Equity-Based Compensation - Add

Equity-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended		9 Months Ended
	Mar. 31, 2023 $ / shares shares	Mar. 31, 2022 Tranche shares	May 31, 2016	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2023 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2022 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period						1 year 7 months 17 days
Common stock, shares issued				89,097,821		89,097,821		87,103,007
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	$ 40.75			$ 39.14	$ 55.59	$ 42.36	$ 72.48
Total fair value amount, Vested | $				$ 4.2	$ 0.1	$ 22.5	$ 8
Number of Shares, Granted				0	0	2,774,271
Risk-free interest rate						4.40%	1.90%
Number of tranches | Tranche		2
Expected dividend yield						0%	0%
Expected volatility						78.70%	76.20%
Expected term						6 years	5 years 10 months 24 days
Weighted average grant date fair value per share | $ / shares						$ 28.92	$ 57.23
Total intrinsic value of stock options exercised | $				$ 4.8	$ 1.4	$ 6.6	$ 41.8
Unrecognized compensation cost related to stock options | $				69.2		69.2
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized equity-based compensation expense related to restricted stock | $				$ 143.2		$ 143.2
Weighted average period of unrecognized compensation costs						1 year 10 months 9 days
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period	3 years
Number of Shares, Granted	2,195,135
PSUs [Member] | Senior Executives [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period	3 years
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares	$ 68.55
Number of Shares, Granted	181,743
Risk-free interest rate	4.60%
Expected dividend yield	0%
Expected volatility	84.34%
Expected term	2 years 10 months 2 days
PSUs [Member] | Non-executive Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		66,296
First Anniversary of Original Vesting Date [Member] | RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Granted		21,878
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of stock options granted under the Plan						Stock options granted under the 2015 Plan in 2023 generally vest as to one-third on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining two years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years.
Shares available for future issuance				4,005,307		4,005,307
Percentage of cumulative increase in number of shares for future issuance						4%
2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Description of stock options granted under the Plan			The 2016 Plan allows eligible employees to purchase shares of the Company’s common stock on the last day of each predetermined six-month offering period at 85% of the lower of the fair market value per share at the beginning or end of the applicable offering period.
Percentage of fair market value of common stock			85%
Shares available for future issuance				1,149,953		1,149,953
Common stock, shares issued				69,631	24,316	69,631	24,316
Weighted Average Grant Date Fair Value per Share, Granted | $ / shares						$ 29.45	$ 44
Risk-free interest rate				5.53%	2.52%
Expected dividend yield				0%	0%	0%	0%
Expected volatility				60.40%	95.30%
Expected term				6 months	6 months	6 months	6 months
Maximum | 2016 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued				500,000		500,000

Equity-Based Compensation - Sum

Equity-Based Compensation - Summary of Restricted Stock Activity (Detail) - $ / shares	1 Months Ended	3 Months Ended		9 Months Ended
	Mar. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Number of Shares, Unvested, Beginning balance				1,941,379
Number of Shares, Granted		0	0	2,774,271
Number of Shares, Vested				(597,610)
Number of Shares, Cancelled				(193,503)
Number of Shares, Unvested, Ending balance		3,924,537		3,924,537
Weighted Average Grant Date Fair Value per Share, Unvested, Beginning balance				$ 70.70
Weighted Average Grant Date Fair Value per Share, Granted	$ 40.75	$ 39.14	$ 55.59	42.36	$ 72.48
Weighted Average Grant Date Fair Value per Share, Vested				68.31
Weighted Average Grant Date Fair Value per Share, Cancelled				49.7
Weighted Average Grant Date Fair Value per Share, Unvested, Ending balance		$ 52.07		$ 52.07

Equity-Based Compensation - S_2

Equity-Based Compensation - Summary of Weighted Average Assumptions Used to Compute Fair Value of Option Granted (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate			4.40%	1.90%
Expected term			6 years	5 years 10 months 24 days
Expected volatility of underlying stock			78.70%	76.20%
Expected dividend yield			0%	0%
2016 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate	5.53%	2.52%
Risk-free interest rate, Minimum			4.70%	0.22%
Risk-free interest rate , Maximum			5.53%	2.52%
Expected term	6 months	6 months	6 months	6 months
Expected volatility of underlying stock	60.40%	95.30%
Expected volatility of underlying stock, Minimum			60.40%	63.60%
Expected volatility of underlying stock, Maximum			69.20%	95.30%
Expected dividend yield	0%	0%	0%	0%

Equity-Based Compensation - S_3

Equity-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2023
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding, Beginning Balance	5,471,675
Number of options, Granted	569,821
Number of options, Exercised	(319,847)
Number of options, Forfeited	(130,474)
Number of Options, Outstanding, Ending Balance	5,591,175
Number of Options, Exercisable	3,846,015
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance	$ 49.86
Weighted Average Exercise Price per Share, Granted	41
Weighted Average Exercise Price per Share, Exercised	17.52
Weighted Average Exercise Price per Share, Forfeited	80.2
Weighted Average Exercise Price per Share, Outstanding, Ending Balance	50.1
Weighted Average Exercise Price per Share, Exercisable	$ 42.52
Weighted Average Remaining Contractual Term, Outstanding	6 years 10 months 13 days
Weighted Average Remaining Contractual Term, Exercisable	6 years 3 months 18 days
Aggregate Intrinsic Value, Outstanding	$ 39,821
Aggregate Intrinsic Value, Exercisable	$ 36,370

Loss Per Share - Schedule of Ba

Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended					9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Earnings Per Share [Abstract]
Net loss	$ (122,224)	$ (123,681)	$ (113,229)	$ (100,678)	$ (146,872)	$ (349,031)	$ (360,779)
Weighted average shares outstanding, basic	88,645		76,047			88,204	75,543
Weighted average shares outstanding, diluted	88,645		76,047			88,204	75,543
Net loss per share, basic	$ (1.38)		$ (1.49)			$ (3.96)	$ (4.78)
Net loss per share, diluted	$ (1.38)		$ (1.49)			$ (3.96)	$ (4.78)

Loss Per Share - Potential Dilu

Loss Per Share - Potential Dilutive Securities Excluded from Computation of Diluted Net Loss Per Common Share (Detail) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	9,516	7,476	9,516	7,476
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	3,925	1,928	3,925	1,928
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	5,591	5,548	5,591	5,548

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule of Changes in Stockholders Equity (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Class Of Stock [Line Items]
Beginning balance	$ 1,104,888		$ 1,235,584	$ 880,547	$ 953,754	$ 1,040,244	$ 1,235,584	$ 1,040,244
Beginning balance, shares			87,103,007				87,103,007
Exercise of stock options	4,384	$ 465		722	4,827	8,435
Exercise of stock options, shares							319,847
Issuance of shares under employee stock purchase plan		2,051			1,068
Equity-based compensation	35,352	36,400		25,215	23,068	18,491
Other comprehensive loss - unrealized loss on marketable securities	142	(1,482)		(991)	(932)	(5,128)
Other comprehensive gain (loss) from equity method investment	154	292		(805)	(560)	(302)	$ 2,240	(1,667)
Net loss	(122,224)	(123,681)		(113,229)	(100,678)	(146,872)	(349,031)	(360,779)
Ending balance	$ 1,037,414	1,104,888		824,951	880,547	953,754	$ 1,037,414	824,951
Ending balance, shares	89,097,821						89,097,821
At The Market Offerings [Member]
Class Of Stock [Line Items]
Beginning balance		1,190,843	$ 1,235,584				$ 1,235,584
Issuance of common stock	$ 14,718		1,466	31,510		38,886
Contingent consideration paid to Rewrite Holders			24,126
Exercise of stock options			755
Equity-based compensation			27,255
Other comprehensive loss - unrealized loss on marketable securities			2,989
Other comprehensive gain (loss) from equity method investment			1,794
Net loss			(103,126)
Ending balance			1,190,843
Common Stock [Member]
Class Of Stock [Line Items]
Beginning balance	$ 9	$ 9	$ 9	$ 8	$ 8	$ 7	$ 9	$ 7
Beginning balance, shares	88,347,634	88,095,779	87,103,007	76,000,745	75,624,167	74,485,883	87,103,007	74,485,883
Contingent consideration paid to Rewrite Holders			$ 567,045
Exercise of stock options, shares	241,123	30,371	48,353	33,336	315,747	503,830
Vesting of restricted stock units, shares	103,732	151,853	342,025	662	36,515	54,666
Issuance of shares under employee stock purchase plan, shares		69,631			24,316
Ending balance	$ 9	$ 9	$ 9	$ 8	$ 8	$ 8	$ 9	$ 8
Ending balance, shares	89,097,821	88,347,634	88,095,779	76,587,947	76,000,745	75,624,167	89,097,821	76,587,947
Common Stock [Member] | At The Market Offerings [Member]
Class Of Stock [Line Items]
Issuance of common stock						$ 1
Number of stock additionally invested	405,332		35,349	553,204		579,788
Additional Paid-In Capital [Member]
Class Of Stock [Line Items]
Beginning balance	$ 2,512,741	$ 2,473,825	$ 2,420,223	$ 1,840,644	$ 1,811,681	$ 1,745,870	$ 2,420,223	$ 1,745,870
Contingent consideration paid to Rewrite Holders			24,126
Exercise of stock options	4,384	465	755	722	4,827	8,435
Issuance of shares under employee stock purchase plan		2,051			1,068
Equity-based compensation	35,352	36,400	27,255	25,215	23,068	18,491
Ending balance	2,567,195	2,512,741	2,473,825	1,898,091	1,840,644	1,811,681	2,567,195	1,898,091
Additional Paid-In Capital [Member] | At The Market Offerings [Member]
Class Of Stock [Line Items]
Issuance of common stock	14,718		1,466	31,510		38,885
Accumulated Other Comprehensive Loss [Member]
Class Of Stock [Line Items]
Beginning balance	(3,868)	(2,678)	(7,461)	(9,554)	(8,062)	(2,632)	(7,461)	(2,632)
Other comprehensive loss - unrealized loss on marketable securities	142	(1,482)	2,989	991	(932)	(5,128)
Other comprehensive gain (loss) from equity method investment	154	292	1,794	(805)	(560)	(302)
Ending balance	(3,572)	(3,868)	(2,678)	(9,368)	(9,554)	(8,062)	(3,572)	(9,368)
Accumulated Deficit [Member]
Class Of Stock [Line Items]
Beginning balance	(1,403,994)	(1,280,313)	(1,177,187)	(950,551)	(849,873)	(703,001)	(1,177,187)	(703,001)
Net loss	(122,224)	(123,681)	(103,126)	(113,229)	(100,678)	(146,872)
Ending balance	$ (1,526,218)	$ (1,403,994)	$ (1,280,313)	$ (1,063,780)	$ (950,551)	$ (849,873)	$ (1,526,218)	$ (1,063,780)

Stockholders' Equity - Schedu_2

Stockholders' Equity - Schedule of Changes in Stockholders Equity (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Mar. 31, 2022
Class Of Stock [Line Items]
Stock issuance cost, net	$ 81	$ 62	$ 54	$ 164

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended			3 Months Ended	9 Months Ended
	Sep. 30, 2023	Mar. 31, 2022	Aug. 31, 2019	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Class Of Stock [Line Items]
Common stock, shares authorized	240,000,000				240,000,000		120,000,000
2019 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering				$ 38.9
Percentage of gross proceeds from common stock as sales agent cash commission			3%
Stock Issued During Period, Shares, New Issues			3,778,889	579,788
Common stock price per share		$ 69.43		$ 69.43
2019 Sales Agreement [Member] | General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees				$ 0.2
2019 Sales Agreement [Member] | Maximum
Class Of Stock [Line Items]
Proceeds from common stock offering			$ 150
2022 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering					$ 16.2	$ 31.5
Proceeds From Sale of Marketable Securities						$ 8.3
Percentage of gross proceeds from common stock as sales agent cash commission		3%
Stock Issued During Period, Shares, New Issues	3,836,020				440,681	553,204
Common stock price per share	$ 38.2				$ 38.2	$ 58.82
Legal accounting and other fees						$ 0.1
Proceeds from common stock offering	$ 188.2				$ 188.2
2022 Sales Agreement [Member] | General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees					$ 0.1
2022 Sales Agreement [Member] | Maximum
Class Of Stock [Line Items]
Proceeds from common stock offering		$ 400

Related Party Transactions - Ad

Related Party Transactions - Additional information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Related Party Transaction [Line Items]
Revenue	$ 1,000		$ 6,600
AvenCell [Member]
Related Party Transaction [Line Items]
Revenue	$ 1,900		$ 13,200
Avencelllca [Member] | Joint Venture AvenCell [Member]
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	33.33%		33.33%
Avencellcoco [Member]
Related Party Transaction [Line Items]
Revenue	$ 0	$ 1,300
Contra Revenue			$ 600	$ 1,400