0000950170-22-021835 | 10-Q | XBRL Viewer | Intellia Therapeutics INC

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2022	Oct. 31, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2022
Document Fiscal Year Focus	2022
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		78,684,039
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 Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Current Assets:
Cash and cash equivalents	$ 141,194	$ 123,406
Marketable securities	687,000	625,282
Accounts receivable ($0 million and $0.1 million, respectively, from related party)	4,023	2,031
Prepaid expenses and other current assets	26,730	18,584
Total current assets	858,947	769,303
Marketable securities - noncurrent	20,533	337,361
Property and equipment, net	26,597	20,968
Operating lease right-of-use assets	101,290	79,143
Equity method investment	40,102	58,131
Investments and other assets	36,989	29,558
Total Assets	1,084,458	1,294,464
Current Liabilities:
Accounts payable	4,384	9,653
Accrued expenses ($1.0 million and $0 million, respectively, from related party)	58,379	43,309
Current portion of operating lease liability	13,551	9,112
Current portion of deferred revenue ($28.5 million and $34.2 million, respectively, from related party)	54,818	63,759
Total current liabilities	131,132	125,833
Deferred revenue, net of current portion ($0 million and $19.9 million, respectively, from related party)	25,678	63,476
Long-term operating lease liability	84,097	64,911
Contingent consideration liability	18,600	0
Commitments and contingencies (Note 6)
Stockholders’ Equity:
Common stock, $0.0001 par value; 120,000,000 shares authorized; 76,587,947 and 74,485,883 shares issued and outstanding at September 30, 2022 and December 31, 2021, respectively	8	7
Additional paid-in capital	1,898,091	1,745,870
Accumulated other comprehensive loss	(9,368)	(2,632)
Accumulated deficit	(1,063,780)	(703,001)
Total stockholders’ equity	824,951	1,040,244
Total Liabilities and Stockholders’ Equity	$ 1,084,458	$ 1,294,464

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Accounts receivable, related party	$ 0.0	$ 0.1
Accrued expenses from related party	1.0	0.0
Current portion of deferred revenue, related party	28.5	34.2
Deferred revenue, net of current portion, related party	$ 0.0	$ 19.9
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	76,587,947	74,485,883
Common stock, shares outstanding	76,587,947	74,485,883

- Definition

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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+ Details

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Collaboration revenue	$ 13,266	$ 7,204	$ 38,548	$ 20,199
Type of Revenue [Extensible List]	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember	us-gaap:LicenseAndServiceMember
Operating expenses:
Research and development	$ 96,651	$ 60,486	$ 319,945	$ 158,646
General and administrative	22,145	18,711	66,680	48,988
Total operating expenses	118,796	79,197	386,625	207,634
Operating loss	(105,530)	(71,993)	(348,077)	(187,435)
Other (expense) income, net:
Interest income	1,945	349	3,188	780
Loss from equity method investment	(1,834)	0	(7,831)	0
Change in fair value of contingent consideration	(7,810)	0	(8,059)	0
Total other (expense) income, net	(7,699)	349	(12,702)	780
Net loss	$ (113,229)	$ (71,644)	$ (360,779)	$ (186,655)
Net Loss Per Share, Basic	$ (1.49)	$ (0.97)	$ (4.78)	$ (2.68)
Net Loss Per Share, Diluted	$ (1.49)	$ (0.97)	$ (4.78)	$ (2.68)
Weighted average shares outstanding, basic	76,047	73,706	75,543	69,720
Weighted average shares outstanding, diluted	76,047	73,706	75,543	69,720
Other comprehensive loss:
Unrealized gain (loss) on marketable securities	$ 991	$ (161)	$ (5,069)	$ (175)
Other comprehensive loss from equity method investment	(805)	0	(1,667)	0
Comprehensive loss	$ (113,043)	$ (71,805)	$ (367,515)	$ (186,830)

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Income Statement [Abstract]
Revenue from related party	$ 4,414	$ 277	$ 15,612	$ 277

- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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+ Details

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (360,779)	$ (186,655)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,541	5,011
Gain on disposal of property and equipment	(162)	0
Equity-based compensation	66,774	32,448
Amortization of investment premiums	5,252	4,970
Loss from equity method investment	7,831	0
Deferral of equity method investment intra-entity profit on sales	8,530	0
Change in fair value of contingent consideration	8,059	0
In-process research and development charge	55,990	0
Changes in operating assets and liabilities:
Accounts receivable	(1,992)	(361)
Prepaid expenses and other current assets	(228)	(5,073)
Operating lease right-of-use assets	8,516	6,761
Other assets	(982)	(248)
Accounts payable	(5,334)	(1,870)
Accrued expenses	12,852	(1,170)
Deferred revenue	(46,739)	(16,986)
Operating lease liabilities	(6,547)	(7,206)
Net cash used in operating activities	(243,418)	(170,379)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(9,646)	(9,888)
Purchases of marketable securities	(192,598)	(772,759)
Maturities of marketable securities	437,387	390,984
Proceeds from sale of property and equipment	150	0
Acquired in-process research and development, net of cash acquired of $287	(44,832)	0
Net cash provided by (used in) investing activities	190,461	(391,663)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from options exercised	13,984	39,868
Issuance of shares through employee stock purchase plan	1,068	970
Net cash provided by financing activities	77,192	734,408
Net increase in cash and cash equivalents and restricted cash equivalents	24,235	172,366
Cash and cash equivalents and restricted cash equivalents, beginning of period	125,486	164,606
Cash and cash equivalents and restricted cash equivalents, end of period	149,721	336,972
Reconciliation of cash and cash equivalents and restricted cash equivalents to condensed consolidated balance sheet:
Cash and cash equivalents	141,194	334,736
Restricted cash equivalents, included in investments and other assets	8,527	2,236
Total cash and cash equivalents and restricted cash equivalents	149,721	336,972
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	2,180	633
Right-of-use asset acquired under operating lease	30,663	49,435
Contingent consideration liability assumed in asset acquisition	10,541	0
Proceeds from at-the-market offerings unpaid at period end	8,255	0
Non-cash trade-in of property and equipment	200	0
AvenCell [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Loss from equity method investment	(8,500)
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property to AvenCell Therapeutics, Inc.	0	62,900
Follow-on Offering [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	0	648,315
At The Market Offerings [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	$ 62,140	$ 45,255

Condensed Consolidated Statements of Cash Flows (Unaudited) (Parenthetical) $ in Thousands	9 Months Ended
	Sep. 30, 2022 USD ($)
Net of cash acquired	$ 287

Overview and Basis of Presentation

9 Months Ended

Sep. 30, 2022

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 novel, potentially curative therapeutics leveraging CRISPR/Cas9-based technologies. CRISPR/Cas9, an acronym for Clustered, Regularly Interspaced Short Palindromic Repeats (“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. The Company's in vivo programs use intravenously administered CRISPR as the therapy, in which proprietary delivery technology enables highly precise editing of disease-causing genes directly within specific target tissues. The Company's ex vivo programs use CRISPR to create the therapy by using engineered human cells to treat cancer and autoimmune diseases. The Company's deep scientific, technical and clinical development experience, along with its robust intellectual property (“IP”) portfolio, have enabled it to take a leadership role in harnessing the full potential of genome editing 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, 2021.

On February 2, 2022, the Company entered into an Agreement and Plan of Merger (the “Rewrite Merger Agreement”) with RW Acquisition Corp., a Delaware corporation and a wholly owned subsidiary of the Company (“Merger Sub”), Rewrite Therapeutics, Inc., a Delaware corporation (“Rewrite”) and Shareholder Representative Services LLC, a Colorado limited liability company, solely in its capacity as the representative of the Rewrite Holders (as defined below). On the effective date of the Rewrite Merger Agreement, Merger Sub merged with and into Rewrite, with Rewrite surviving as a wholly owned subsidiary of the Company. In September 2022, Rewrite merged with and into Intellia, with Intellia as the surviving corporation. Pursuant to the Rewrite Merger Agreement, and subject to the terms and conditions thereof, the Company paid Rewrite’s former stockholders and optionholders (the “Rewrite Holders”) upfront consideration in an aggregate amount of approximately $45.0 million payable in cash, excluding customary purchase price adjustments. In addition, the Rewrite Holders will be eligible to receive up to an additional $155.0 million in milestone payments upon the achievement of certain pre-specified research and regulatory approval milestones, payable through a mixture of $130.0 million in cash and $25.0 million in a combination of cash and shares of common stock, par value $0.0001 per share (“Common Stock”) of the Company. The shares of Common Stock will be valued using the volume-weighted average price of Common Stock of the Company 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.

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 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 extent of the impact of the coronavirus disease 19 (“COVID-19”) pandemic on the Company’s operational and financial

performance will depend on certain developments, including the length and severity of this pandemic, as well as its effect on the Company’s employees, collaborators and vendors, all of which are uncertain and cannot be predicted. The Company cannot reasonably estimate the extent to which the disruption may materially impact its consolidated results of operations or financial position.

The effects of material revisions in estimates are 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, 2022, the Company has raised an aggregate of approximately $1,887.2 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. An additional $8.3 million related to at-the-market offerings was recorded as an other current asset on the Company's condensed consolidated balance sheet as of September 30, 2022, representing offerings with trade dates in September 2022 that were settled in October 2022. The Company expects that its cash, cash equivalents and marketable securities as of September 30, 2022 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 Accounting Policies

9 Months Ended

Sep. 30, 2022

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, 2021. There have been no material changes during the nine months ended September 30, 2022 except for the following.

Asset acquisitions

At the time of acquisition, the Company determines if a transaction should be accounted for as a business combination or acquisition of assets. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs, and the consideration is allocated to the items acquired based on a relative fair value methodology. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire in-process research and development with no alternative future use is charged to research and development expense at the acquisition date.

Contingent consideration

The Company accounts for contingent consideration identified in an asset acquisition, that is payable in cash and does not meet the definition of a derivative under Accounting Standard Codification (“ASC”) 815, Derivatives and Hedging, when the contingency is resolved and the consideration is paid or becomes payable.

The Company accounts for contingent consideration identified in an asset acquisition that is settled in shares of common stock under ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). The contingent consideration liability will be recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in other (expense) income in the condensed consolidated statements of operations and comprehensive loss.

The estimated fair value of the contingent consideration liability related to the Rewrite acquisition (see Notes 4 and 9) is determined based on a probability adjusted discounted cash flow model that includes significant estimates and assumptions pertaining to research and development. Significant changes in any of the probabilities of success or in the probabilities as to the periods in which the milestone would be achieved would result in a significantly higher or lower fair value measurement. The Company will continue to adjust the liability for changes in fair value until the obligation is settled or the research is abandoned.

Marketable Securities

9 Months Ended

Sep. 30, 2022

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, 2022 and December 31, 2021 at net book value:


	September 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury and other government securities	$	295,367	$	-	$	(3,840	)	$	291,527
Financial institution debt securities		327,417		-		(2,154	)		325,263
Corporate debt securities		67,018		-		(772	)		66,246
Other asset-backed securities		24,925		-		(428	)		24,497
Total	$	714,727	$	-	$	(7,194	)	$	707,533

	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury and other government securities	$	301,493	$	-	$	(1,016	)	$	300,477
Financial institution debt securities		441,068		-		(652	)		440,416
Corporate debt securities		62,500		-		(151	)		62,349
Other asset-backed securities		159,707		-		(306	)		159,401
Total	$	964,768	$	-	$	(2,125	)	$	962,643

The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. At September 30, 2022 and December 31, 2021, 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 realized gains or losses in the nine months ended September 30, 2022 or for the year ended December 31, 2021. 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, 2022 and December 31, 2021, the Company did not hold any investments that matured beyond five years of the balance sheet date.

Fair Value Measurements

9 Months Ended

Sep. 30, 2022

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, 2022 and December 31, 2021, the Company’s financial assets and liabilities recognized at fair value on a recurring basis consisted of the following:


	Fair Value as of September 30, 2022
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets
Cash equivalents and restricted cash equivalents	$	139,471	$	139,471	$	-	$	-
Marketable securities:
U.S. Treasury and other government securities		291,527		276,621		14,906		-
Financial institution debt securities		325,263		-		325,263		-
Corporate debt securities		66,246		-		66,246		-
Other asset-backed securities		24,497		-		24,497		-
Total marketable securities		707,533		276,621		430,912		-
Total Assets	$	847,004	$	416,092	$	430,912	$	-

Liabilities
Contingent consideration liability - research	$	18,600	$	-	$	-	$	18,600
Total Liabilities	$	18,600	$	-	$	-	$	18,600

	Fair Value as of December 31, 2021
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets
Cash equivalents and restricted cash equivalents	$	124,636	$	124,636	$	-	$	-
Marketable securities:
U.S. Treasury and other government securities		300,477		280,085		20,392		-
Financial institution debt securities		440,416		-		440,416		-
Corporate debt securities		62,349		-		62,349		-
Other asset-backed securities		159,401		-		159,401		-
Total marketable securities		962,643		280,085		682,558		-
Total Assets	$	1,087,279	$	404,721	$	682,558	$	-

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. After completing its validation procedures, the Company did not adjust or override any fair value measurements provided by the pricing services as of September 30, 2022 or December 31, 2021.

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.

The Company's investment in AvenCell Therapeutics, Inc. (“AvenCell”) was initially recorded at fair value, determined according to Level 3 inputs in the fair value hierarchy described above. Refer to Note 8 for further details.

The Company's investment in SparingVision SAS (“SparingVision”) was initially recorded at fair value, determined according to Level 3 inputs in the fair value hierarchy described above. The Company's investment in Kyverna Therapeutics, Inc. (“Kyverna”) was recorded at cost, which is representative of fair value. Refer to Note 8 for further details. The SparingVision and Kyverna investments (the “investments”) are included in “Investments and other assets” on the condensed consolidated balance sheet. These investments are accounted for using the measurement alternative at cost minus impairment adjusted for changes in observable prices. There were no changes in observable prices of these investments as of September 30, 2022.

As discussed further in Note 9, under the Rewrite Merger Agreement, the Rewrite Holders are eligible to receive a $25.0 million research milestone payment, payable in a combination of cash and the Company’s common stock valued using the volume-weighted average price of the Company’s stock over the ten-day trading period ending two trading days prior to the date on which the applicable milestone is achieved. The milestone payable in the Company’s common stock results in liability classification under ASC 480. This contingent consideration liability is 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 is classified within Level 3 of the fair value hierarchy.

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 ended September 30, 2022
Balance at February 2, 2022 (at inception)	$	10,541
Change in fair value		8,059
Balance at September 30, 2022	$	18,600


	As of inception (February 2, 2022)		As of September 30, 2022
Discount rate	7%		12.6%
Probability of achievement	50%		80%
Projected year of achievement		2024		2023

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accrued Expenses

9 Months Ended

Sep. 30, 2022

Payables and Accruals [Abstract]

Accrued Expenses

5. Accrued Expenses

Accrued expenses consisted of the following:


	September 30,		December 31,
	2022		2021
	(In thousands)
Accrued research and development	$	30,346	$	16,979
Employee compensation and benefits		17,923		20,359
Accrued legal and professional expenses		2,976		3,100
Accrued other		7,134		2,871
Total accrued expenses	$	58,379	$	43,309

Commitments and Contingencies

9 Months Ended

Sep. 30, 2022

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

6. Commitments and Contingencies

Litigation

There have been no material changes to any of the outstanding litigation, nor is the Company a party to any new litigation, since December 31, 2021. 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, 2021.

License Agreements

The Company is party to license agreements, which include contingent payments. These payments will become payable if and when certain development, regulatory and commercial milestones are achieved. As of September 30, 2022, the satisfaction and timing of the contingent payments is uncertain and not reasonably estimable.

Collaborations and Other Arrangements

9 Months Ended

Sep. 30, 2022

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 that can augment its leadership in CRISPR/Cas9 therapeutic development. As of September 30, 2022, the Company’s accounts receivable were related to its collaboration with Regeneron Pharmaceuticals, Inc. (“Regeneron”), and the Company's contract liabilities were related to its collaborations with Regeneron, AvenCell, SparingVision and Kyverna. As of December 31, 2021, the Company’s accounts receivable were related to its collaborations with Regeneron and AvenCell 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, 2022 and 2021 (in thousands):


	Balance at Beginning of Period		Additions		Deductions			Balance at End of Period
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

	Balance at Beginning of Period		Additions		Deductions			Balance at End of Period
Nine Months Ended September 30, 2021
Accounts receivable	$	2,130	$	5,575	$	(5,214	)	$	2,491
Contract liabilities - deferred revenue	$	73,931	$	62,900	$	(17,049	)	$	119,782

During the nine months ended September 30, 2022 and 2021, 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:	2022		2021
Amounts included in the contract liability at the beginning of the period	$	38,208	$	16,861

Costs to obtain and fulfill a contract

The Company did not incur any expenses to obtain collaboration agreements and costs to fulfill those contracts do not generate or enhance resources of the Company. As such, no costs to obtain or fulfill a contract have been capitalized in any period.

Regeneron Pharmaceuticals, Inc.

License and Collaboration Agreement

In April 2016, the Company entered into a license and collaboration agreement with Regeneron (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”).

On May 30, 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 collaboration was extended until April 2024, at which point Regeneron has an option

to renew for an additional two years. The 2020 Regeneron Amendment also grants 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.

Since December 31, 2021, there have been no material changes to the key terms of the 2016 Regeneron Agreement and the 2020 Regeneron Amendment (the “Amended Agreements”). For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2021.

Revenue Recognition – Collaboration Revenue. Through September 30, 2022, excluding amounts allocated to Regeneron’s purchase of the Company’s common stock, the Company recorded $145.0 million in upfront payments under the Amended Agreements and $39.7 million for research and development services, primarily under the ATTR Co/Co agreement. Through September 30, 2022, the Company has recognized $167.6 million of collaboration revenue under all arrangements, including $6.5 million and $18.6 million during the three and nine months ended September 30, 2022, respectively, and $6.7 million and $18.7 million during the three and nine months ended September 30, 2021, respectively, in the condensed consolidated statements of operations and comprehensive loss. This includes $4.0 million and $8.7 million during the three and nine months ended September 30, 2022, respectively, and $2.1 million and $3.9 million during the three and nine months ended September 30, 2021, 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 $3.2 million and $6.9 million during the three and nine months ended September 30, 2022, respectively, and $1.1 million and $2.1 million during the three and nine months ended September 30, 2021, respectively.

As of September 30, 2022, there was approximately $34.5 million of the aggregate transaction price of the Amended Agreements remaining to be recognized, which the Company expects to be recognized during the research term through April 2024.

As of September 30, 2022 and December 31, 2021, the Company had accounts receivable of $4.0 million and $2.0 million, respectively. The Company had deferred revenue of $34.5 million and $51.4 million as of September 30, 2022 and December 31, 2021, respectively, related to the Amended Agreements.

AvenCell Therapeutics, Inc.

On July 30, 2021 (the “Effective Date”), 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 will co-develop and co-commercialize allogeneic universal CAR-T cell products for an immuno-oncology indication.

Since December 31, 2021, there have been no material changes to the key terms of the AvenCell LCA and AvenCell Co/Co agreements. For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company's Annual Report for the year ended December 31, 2021.

Revenue Recognition – Collaboration Revenue. The Company recognized $5.7 million and $17.1 million in revenue related to the AvenCell LCA for the three and nine months ended September 30, 2022, respectively, after eliminating $2.9 million and $8.5 million in intra-entity profits during those respective periods. The Company recognized $125.0 thousand in revenue and eliminated $62.5 thousand in intra-entity profits related to the AvenCell LCA for the three and nine months ended September 30, 2021. The elimination of intra-entity profits results in the deferral of revenue that will be 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 $1.3 million and $1.4 million in contra-revenue in the three and nine months ended September 30, 2022 related to the AvenCell Co/Co agreement. The Company recognized $0.2 million in revenues related to the AvenCell Co/Co agreement for the three and nine months ended September 30, 2021.

As of September 30, 2022, there was approximately $28.5 million of the aggregate transaction price of the AvenCell LCA remaining to be recognized, which the Company expects to recognize through July 2023.

As of September 30, 2022, the Company did not have accounts receivable related to the AvenCell Co/Co or AvenCell LCA agreements. As of December 31, 2021, the Company had $0.1 million in accounts receivable related to the AvenCell Co/Co agreement. The Company had deferred revenue of $28.5 million and $54.1 million as of September 30, 2022 and December 31, 2021, respectively, related to the AvenCell LCA.

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, 2021, there have been no material changes to the key terms of the SparingVision LCA agreement. For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company's Annual Report for the year ended December 31, 2021.

The Company did not recognize collaboration revenue in the three or nine months ended September 30, 2022 and 2021 related to the SparingVision LCA. As of September 30, 2022 and December 31, 2021, the Company did not have accounts receivable related to the SparingVision LCA. As of September 30, 2022 and December 31, 2021, the Company had deferred revenue of $14.8 million 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 licensing 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, 2021, there have been no material changes to the key terms of the Kyverna LCA agreement. For further information on the terms and conditions of this agreement, please see the notes to the consolidated financial statements included in the Company's Annual Report for the year ended December 31, 2021.

The Company recognized $2.3 million and $4.3 million in revenue for the three and nine months ended September 30, 2022, respectively, related to the Kyverna LCA. As of September 30, 2022 and December 31, 2021, the Company did not have accounts receivable related to the Kyverna LCA. As of September 30, 2022 and December 31, 2021 the Company had deferred revenue of $2.7 million and $7.0 million, respectively, related to the Kyverna LCA, which is expected to be recognized through January 2023.

ONK Therapeutics, Ltd.

On February 12, 2022 the Company entered into a license, collaboration and option agreement (the “ONK LCA”) with ONK Therapeutics, Ltd. (“ONK”), an innovative company dedicated to developing optimally engineered natural killer (“NK”) cell therapies to cure patients with cancer.

Scope: The agreement grants ONK a non-exclusive license to the Company's proprietary ex vivo CRISPR/Cas9-based genome editing platform and its Lipid Nanoparticle (“LNP”)-based delivery technologies for development of up to five allogeneic NK cell therapy products, which license is exclusive with respect to certain guide ribonucleic acids (“gRNAs”).

Responsibilities in the earlier stage of the license and collaboration agreement (the “evaluation program”) will be shared between the two parties, with each party bearing their own cost burden. Upon completion of the evaluation program, ONK will identify up to five allogeneic targets for further development under a development program. Once these allogeneic targets have been selected by ONK, any further development costs incurred by the Company are eligible for reimbursement. ONK will be responsible for preclinical and clinical development for the engineered NK cell therapies enabled by the agreement.

Financial Terms: The Company will be eligible to receive up to $184 million per product in future development and commercial milestone payments as achieved, as well as up to mid-single digit royalties on potential future sales. In addition, the agreement grants the Company options to co-develop and co-commercialize up to two products developed through the collaboration worldwide with rights to lead commercialization in the U.S. There is no fee related to the exercise of these co-development and co-commercialization options.

Governance: The parties formed a joint steering committee, which is responsible for monitoring and managing the collaboration prior to program completion.

ONK LCA – Accounting Analysis: The Company determined that the accounting for the ONK LCA is within the scope of Accounting Standards Update (“ASU”) 2014-09, Revenue from Contracts with Customers (Topic 606) and its related amendments (collectively known as ASC 606). The Company identified one combined performance obligation related to the license, evaluation and development programs. The LCA did not include an exchange of upfront consideration between the parties. As the ONK LCA progresses, the Company will incur certain expenses. Expenses incurred under the evaluation program will be accounted for under ASC 730, Research and Development. Reimbursements under the development programs represent variable constrained consideration, whereas the Company is acting as the principal, and revenue will be recognized as expenses are incurred. Milestone payments and royalties are constrained consideration and will be recorded as revenue upon achievement. There was no revenue recognized in the three or nine months ended September 30, 2022 related to the ONK LCA.

Novartis Institutes for BioMedical Research, Inc.

In December 2014, the Company entered into a strategic collaboration agreement with Novartis Institutes for BioMedical Research, Inc. (“Novartis”) (the “2014 Novartis Agreement”), primarily focused on the research of new ex vivo CRISPR/Cas9-edited therapies using CAR-T cells and hematopoietic stem cells (“HSCs”). The agreement was amended in December 2018 (the “Novartis Amendment”) to also include research on ocular stem cells (“OSCs”). In December 2019, per the terms of the 2014 Novartis Agreement, the research term ended, although the 2014 Novartis Agreement remains in effect, for which the Company will be eligible to receive milestone and royalty payments in the future. In June 2021, the Company entered into Amendment No. 3 (the “Amendment”) to the 2014 Novartis Agreement. The Amendment amends Novartis’ rights with respect to all of the CAR-T Therapeutic Targets (as defined in the 2014 Novartis Agreement) that Novartis selected under the 2014 Novartis Agreement, including (a) making Novartis’ license non-exclusive for such CAR-T Therapeutic Targets, (b) removing Novartis’ diligence and related reporting obligations for such CAR-T Therapeutic Targets, and (c) refining the scope of Novartis’ sublicense rights for such CAR-T Therapeutic Targets. The Company made a one-time payment to Novartis of $10.0 million within 30 days after the effective date of the Amendment, which was recorded as research and development expense in the consolidated statement of operations and comprehensive loss for the year ended December 31, 2021. Since December 31, 2021, there have been no other material changes to the key terms of the 2014 Novartis Agreement and the Novartis Amendments. For further information on the terms and conditions of these agreements, please see the notes to the consolidated financial statements included in the Company’s Annual Report for the year ended December 31, 2021.

Revenue Recognition – Milestone: No milestones under the 2014 Novartis Agreement and the Novartis Amendments were achieved during the three or nine months ended September 30, 2022. In September 2021, a milestone related to a CRISPR/Cas9-based engineered cell therapy for the treatment of sickle cell disease was reached and, as a result, the Company recognized $0.3 million as collaboration revenue within the condensed consolidated statement of operations and comprehensive loss. The Company is eligible to receive additional downstream success-based milestones and royalties.

As of September 30, 2022 and December 31, 2021, the Company had no accounts receivable or deferred revenue related to the 2014 Novartis Agreement and the Novartis Amendments.

Equity-Method Investment and Other Investments

9 Months Ended

Sep. 30, 2022

Equity Method Investments and Joint Ventures [Abstract]

Equity-Method Investment and Other Investments

8. Equity-Method Investment and Other Investments

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 does not consolidate the financial statements of AvenCell and accounts for its investment using the equity method of accounting.

As of the closing date, the fair value of the Company’s investment in AvenCell was $62.9 million which represented the fair value of the preferred stock received in exchange for the exclusive license to the Company’s CRISPR/Cas9 allogeneic platform (see Note 7). In determining the fair value of the Company’s investment, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (76%), the probability of AvenCell achieving certain milestones to obtain subsequent financings (75%) and the discount for lack of marketability (11%).

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 is recording its share of losses from AvenCell on a quarterly basis on a one-quarter lag. During the third quarter of 2022, the Company recorded its share of the three months of AvenCell's losses generated in the second quarter of 2022 in the Company's operating results and other comprehensive loss, resulting in a reduction of the Company's investment by $2.6 million and $9.5 million for the three and nine months ended September 30, 2022, respectively. The elimination of the intra-entity profit component of $2.9 million and $8.5 million (see Note 7) in the three and nine months ended September 30, 2022, respectively, resulted in a further reduction in the balance of the investment in AvenCell, bringing the carrying value of the investment to $40.1 million as of September 30, 2022. The Company is not aware of any material events or transactions during the quarter ended September 30, 2022 that would warrant additional disclosure or recognition in the financial statements.

At September 30, 2022, 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. In determining the fair value of the SparingVision investments, the Company used an option pricing model which requires the input of certain subjective assumptions. The key assumptions used in the option pricing model, which are level 3 inputs, include the anticipated holding period to an exit and liquidity event, the volatility of market participants (90%), and the rate of return (65%). 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, 2022.

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, 2022.

Rewrite Acquisition

9 Months Ended

Sep. 30, 2022

Business Combinations [Abstract]

Rewrite Acquisition

9. Rewrite Acquisition

On February 2, 2022, the Company entered into the Rewrite Merger Agreement. Under the Rewrite Merger Agreement, the Company paid 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 have been 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 in milestone payments upon the achievement of certain pre-specified research and regulatory approval milestones, 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 will 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.

The Company determined that the research milestone settled in the Company’s common stock is classified as a contingent consideration liability under ASC 480 and, therefore, the Company recorded a liability for this milestone payment as of the Rewrite Merger Agreement Date at its fair value of $10.5 million. The contingent consideration liability is 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 (expense) income. The milestones that will be settled in cash will be recorded when the contingency is resolved and the consideration is paid or becomes payable. As of September 30, 2022, none of the milestones that will be settled in cash were resolved.

The transaction price 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

9 Months Ended

Sep. 30, 2022

Leases [Abstract]

Leases

10. Leases

In January 2022, the Company entered into an agreement to lease approximately 38,000 square feet of office and laboratory space at 730 Main Street, Cambridge, Massachusetts under an operating lease agreement (the “730 Main Lease”). The initial term of the 730 Main Lease is for ten years following the Rent Commencement Date and the Company has the option to extend the 730 Main Lease for one five-year term. The base rent under the 730 Main Lease is $130.00 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 determined that in accordance with ASC 842, Leases (Topic 842)(“ASC 842”) the commencement date of the lease had not been met as of September 30, 2022. Therefore, the Company did not record a right of use asset or liability related to the 730 Main Lease during the nine months ended September 30, 2022. The Company anticipates that the lease will commence in the fourth quarter of 2022. In accordance with the 730 Main Lease, the Company is required to maintain a letter of credit in the amount of $2.4 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet.

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 the second half of 2024 for an initial term of twelve years. The Company did not record a right of use asset or liability related to the 840 Winter Lease under ASC 842 during the nine months ended September 30, 2022, as the Company had not taken control of the premises. 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. In accordance with the 840 Winter Lease, the Company is required to maintain an initial letter of credit in the amount of $2.6 million. On or before January 1, 2023, the Company will replace the initial letter of credit with a replacement letter of credit in the amount of $6.0 million. As of September 30, 2022, the restricted cash equivalents related to the initial letter of credit are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The Company has the option to extend the 840 Winter Lease for two five-year terms.

In June 2022, the Company entered into an agreement to lease approximately 62,000 square feet of office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts under an operating lease agreement (the “640 Memorial Drive Lease”). The term of the lease is five years, ending in August 2027. The Company does not have an option to extend the 640 Memorial Drive Lease. The base rent under the 640 Memorial Drive Lease is approximately $97 per square foot per year during the first year of the term, which is subject to scheduled 4% annual increases, plus certain operating expenses and taxes. In September 2022 the Company determined, in accordance with ASC 842, that the commencement date for the lease had been met as the lessor had made the space available for the Company's use. During the period ended September 30, 2022 the Company recorded a right of use asset of $30.7 million and a lease liability of $30.2 million related to the 640 Memorial Drive Lease under ASC 842. The difference between the right of use asset and the lease liability of $0.5 million relates to prepaid rent. In determining the lease liability, the Company used an incremental borrowing rate of 7.99% based on a number of factors including the Company's credit rating and the lease term. In accordance with the 640 Memorial Drive Lease, the Company is required to maintain a letter of credit in the amount of $1.8 million that is restricted for the term of the lease. The restricted cash equivalents are reported in “Investments and other assets” on the Company's condensed consolidated balance sheet. The landlord will also contribute approximately $1.2 million toward the cost of tenant improvements for the premises.

Equity-Based Compensation

9 Months Ended

Sep. 30, 2022

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,
	2022		2021		2022		2021
	(In thousands)
Research and development	$	16,383	$	9,017	$	40,736	$	18,643
General and administrative		8,832		6,393		26,038		13,805
Total	$	25,215	$	15,410	$	66,774	$	32,448

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. Stock options granted under the 2015 Plan generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years.

Effective July 1, 2022, the Company adopted a retirement policy for equity awards granted to all employees other than the Company’s CEO (the “Policy”). The Policy applies to all equity awards granted after the date of adoption to employees who meet certain retirement eligibility criteria set forth in the Policy (the “Retirees”). Pursuant to the terms of the 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, 2022, there were 3,565,012 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 1st by four percent of the number of

shares of stock issued and outstanding on the immediately preceding December 31 or such lesser number of shares of stock as determined by the board of directors.

Restricted Stock Units

RSUs are measured at fair value based on the quoted price of the Company’s common stock.

The following table summarizes the Company’s RSU activity for the nine months ended September 30, 2022:


	Number of Shares			Weighted Average Grant Date Fair Value per Share
Unvested restricted stock units as of December 31, 2021		453,026		$	71.03
Granted		1,648,664			72.48
Vested		(91,843	)		66.53
Cancelled		(82,093	)		76.55
Unvested restricted stock units as of September 30, 2022		1,927,754		$	72.25

In March 2022, the Company granted 794,424 RSUs with a service condition to employees as part of their annual grant, which vest over a period of three years. The weighted average grant date fair value of these RSUs was $79.85 and the vesting start date for these RSUs was January 1, 2022.

Also in March 2022, 55,144 RSUs were granted to senior executives as part of their annual grant. These RSUs have the potential to vest after a period of 3 years, with a vesting start date of January 1, 2022, 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 $126.49. The following assumptions were used to determine the grant date fair value: risk free interest rate: 1.44%; expected dividend yield: 0.0%; expected volatility: 82.53%; expected term (in years): 2.84.

The Company also granted 66,296 performance-based RSUs in March 2022 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, is deemed to be probable of achievement as of September 30, 2022 and the Company recorded $1.2 million in expense related to this tranche in the third quarter. The remaining performance milestones were considered not probable of achievement as of September 30, 2022 and, therefore, no related stock-based compensation was recorded during the period then ending.

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. The weighted-average grant date fair value of RSUs granted during the three and nine months ended September 30, 2021 was $171.65 and $63.13, respectively. The total fair value of RSUs vested (measured on the date of vesting) for the three and nine months ended September 30, 2021 was $3.7 million and $5.7 million, respectively.

As of September 30, 2022, there was $110.4 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 2.3 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 $57.23 per option for those options granted during the nine months ended September 30, 2022 and $105.17 and $50.73 per option for those options granted during the three and nine months ended September 30, 2021, respectively. There were no options granted in the three months ended September 30, 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, 2022 was $1.4 million and $41.8 million, respectively, and during the three and nine months ended September 30, 2021 was $171.3 million and $255.8 million, respectively. Weighted average assumptions used to apply this pricing model were as follows:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2022	2021	2022	2021
Risk-free interest rate	n/a	1.0%	1.9%	0.9%
Expected life of options	n/a	6.0 years	5.9 years	6.0 years
Expected volatility of underlying stock	n/a	75.2%	76.2%	72.7%
Expected dividend yield	n/a	0.0%	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 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.

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 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.

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, 2022:


	Number of Options			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding at December 31, 2021		6,305,156		$	43.57
Granted		391,910			86.08
Exercised		(852,913	)		16.40
Forfeited		(295,691	)		59.08
Outstanding at September 30, 2022		5,548,462		$	49.92		7.63	$	117,003
Exercisable at September 30, 2022		2,855,525		$	33.61

As of September 30, 2022, there was $106.5 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 2.5 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, 2022, there were 1,272,886 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 1st by the lesser of a) one percent of the number of shares of common stock issued and outstanding on the immediately preceding December 31, 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, 2022 and 2021 the Company issued 24,316 and 20,410 shares of common stock under the 2016 Plan, respectively. The weighted-average purchase prices of shares issued under the 2016 Plan were $44.00 and $47.52 per share for the nine-month periods ended September 30, 2022 and 2021, respectively.

The fair value of the awards issued under the 2016 Plan to employees 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,
	2022	2021	2022	2021
Risk-free interest rate	2.52%	0.05%	0.22%-2.52%	0.05%-0.09%
Expected term (in years)	0.5 years	0.5 years	0.5 years	0.5 years
Expected volatility of underlying stock	95.3%	109.2%	63.6%-95.3%	77.5%-109.2%
Expected dividend yield	0.0%	0.0%	0.0%	0.0%

Loss Per Share

9 Months Ended

Sep. 30, 2022

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 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,
	2022			2021			2022			2021
	(In thousands)
Net loss	$	(113,229	)	$	(71,644	)	$	(360,779	)	$	(186,655	)
Weighted average shares outstanding, basic and diluted		76,047			73,706			75,543			69,720
Net loss per share, basic and diluted	$	(1.49	)	$	(0.97	)	$	(4.78	)	$	(2.68	)

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,
	2022		2021
	(In thousands)
Unvested restricted stock units		1,928		443
Stock options		5,548		6,217
		7,476		6,660

Stockholders’ Equity

9 Months Ended

Sep. 30, 2022

Equity [Abstract]

Stockholders’ Equity

13. Stockholders’ Equity

The following tables present changes in stockholders’ equity for the nine-month periods ended September 30, 2022 and 2021 (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, 2021		74,485,883	$	7	$	1,745,870	$	(2,632	)	$	(703,001	)	$	1,040,244
Issuance of common stock through at-the-market offerings, net of issuance costs of $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 marketable securities		-		-		-		(5,128	)		-			(5,128	)
Other comprehensive loss - equity method investment		-		-		-		(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 stock purchase plan		24,316		-		1,068		-			-			1,068
Equity-based compensation		-		-		23,068		-			-			23,068
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(932	)		-			(932	)
Other comprehensive loss - equity method investment		-		-		-		(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 at-the-market offerings, net of issuance costs of $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

					Additional		Accumulated Other						Total
	Common				Paid-In		Comprehensive			Accumulated			Stockholders’
	Shares		Amount		Capital		Loss			Deficit			Equity
Balance at December 31, 2020		66,234,056	$	7	$	962,173	$	1		$	(435,109	)	$	527,072
Issuance of common stock through at-the-market offerings, net of issuance costs of $52		641,709		-		45,255		-			-			45,255
Exercise of stock options		1,014,569		-		13,340		-			-			13,340
Equity-based compensation		-		-		6,424		-			-			6,424
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(13	)		-			(13	)
Net loss		-		-		-		-			(46,205	)		(46,205	)
Balance at March 31, 2021		67,890,334		7		1,027,192		(12	)		(481,314	)		545,873
Exercise of stock options		394,801		-		6,163		-			-			6,163
Vesting of restricted stock units		26,235		-		-		-			-			-
Issuance of shares under employee stock purchase plan		20,410		-		970		-			-			970
Equity-based compensation		-		-		10,614		-			-			10,614
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(1	)		-			(1	)
Net loss		-		-		-		-			(68,806	)		(68,806	)
Balance at June 30, 2021		68,331,780		7		1,044,939		(13	)		(550,120	)		494,813


Issuance of common stock through follow-on offering, net of issuance costs of $284	4,758,620		-		648,315		-			-			648,315
Exercise of stock options	1,227,067		-		20,365		-			-			20,365
Vesting of restricted stock units	24,711		-		-		-			-			-
Equity-based compensation	-		-		15,410		-			-			15,410
Other comprehensive loss	-		-		-		(161	)		-			(161	)
Net loss	-		-		-		-			(71,644	)		(71,644	)
Balance at September 30, 2021	74,342,178	$	7	$	1,729,029	$	(174	)	$	(621,764	)	$	1,107,098

Follow-on Offering

On June 29, 2021, the Company entered into an underwriting agreement related to a public offering of 4,758,620 shares of its common stock (inclusive of shares sold pursuant to the exercise of the underwriters’ option to purchase additional shares) at a public offering price of $145.00 per share. The offering closed on July 2, 2021, for aggregated net proceeds of $648.3 million after deducting $41.7 million in underwriting discounts and offering costs.

At-the-Market Offering Programs

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.

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. As of September 30, 2022, the 2019 Sale Agreement had expired.

In March 2022, the Company entered into an Open Market Sale Agreement (the “2022 Sale Agreement”) with Jefferies, under which Jefferies will be able to offer and sell, from time to time in “at-the-market” offerings, 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.

During the quarter 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, 2022, $367.5 million in shares of common stock remain eligible for sale under the 2022 Sale Agreement.

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

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-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126731327&loc=SL126733271-114008

+ Details

Related Party Transactions

9 Months Ended

Sep. 30, 2022

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 $5.7 million and $17.1 million in revenue related to the AvenCell LCA for the three and nine months ended September 30, 2022, respectively, after eliminating $2.9 million and $8.5 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, the $8.5 million of revenue is indefinitely deferred and excluded from the results of operations of the Company. The Company recognized $125.0 thousand in revenue and eliminated $62.5 thousand in intra-entity profits related to the AvenCell LCA for the three and nine months ended September 30, 2021, respectively. 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, 2022 the

Company had deferred revenue of $28.5 million, all of which is included in current deferred revenue, related to the AvenCell LCA.

Subsequent Events

9 Months Ended

Sep. 30, 2022

Subsequent Events [Abstract]

Subsequent Events

15. Subsequent Events

Through October 27, 2022, the Company issued an additional 1,864,527 shares of its common stock in a series of sales at an average price of $59.26 per share in accordance with the 2022 Sale Agreement, for aggregate net proceeds of $107.2 million after payment of cash commissions to Jefferies. Additionally, the Company received $8.3 million in proceeds in October for the offerings with trade dates in September 2022 that were recorded as an other current asset on the Company's condensed consolidated balance sheet as of September 30, 2022 and settled in October.

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2022
Accounting Policies [Abstract]
Asset acquisitions	Asset acquisitions At the time of acquisition, the Company determines if a transaction should be accounted for as a business combination or acquisition of assets. The Company measures and recognizes asset acquisitions that are not deemed to be business combinations based on the cost to acquire the assets, which includes transaction costs, and the consideration is allocated to the items acquired based on a relative fair value methodology. Goodwill is not recognized in asset acquisitions. In an asset acquisition, the cost allocated to acquire in-process research and development with no alternative future use is charged to research and development expense at the acquisition date.
Contingent Consideration	Contingent consideration The Company accounts for contingent consideration identified in an asset acquisition, that is payable in cash and does not meet the definition of a derivative under Accounting Standard Codification (“ASC”) 815, Derivatives and Hedging, when the contingency is resolved and the consideration is paid or becomes payable. The Company accounts for contingent consideration identified in an asset acquisition that is settled in shares of common stock under ASC 480, Distinguishing Liabilities from Equity (“ASC 480”). The contingent consideration liability will be recorded at fair value at the end of each reporting period with changes in estimated fair values recorded in other (expense) income in the condensed consolidated statements of operations and comprehensive loss. The estimated fair value of the contingent consideration liability related to the Rewrite acquisition (see Notes 4 and 9) is determined based on a probability adjusted discounted cash flow model that includes significant estimates and assumptions pertaining to research and development. Significant changes in any of the probabilities of success or in the probabilities as to the periods in which the milestone would be achieved would result in a significantly higher or lower fair value measurement. The Company will continue to adjust the liability for changes in fair value until the obligation is settled or the research is abandoned.

Marketable Securities (Tables)

9 Months Ended

Sep. 30, 2022

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, 2022 and December 31, 2021 at net book value:


	September 30, 2022
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury and other government securities	$	295,367	$	-	$	(3,840	)	$	291,527
Financial institution debt securities		327,417		-		(2,154	)		325,263
Corporate debt securities		67,018		-		(772	)		66,246
Other asset-backed securities		24,925		-		(428	)		24,497
Total	$	714,727	$	-	$	(7,194	)	$	707,533

	December 31, 2021
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(In thousands)
Marketable securities:
U.S. Treasury and other government securities	$	301,493	$	-	$	(1,016	)	$	300,477
Financial institution debt securities		441,068		-		(652	)		440,416
Corporate debt securities		62,500		-		(151	)		62,349
Other asset-backed securities		159,707		-		(306	)		159,401
Total	$	964,768	$	-	$	(2,125	)	$	962,643

Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2022

Fair Value Disclosures [Abstract]

Summary of Financial Assets Recognized at Fair Value on Recurring Basis

As of September 30, 2022 and December 31, 2021, the Company’s financial assets and liabilities recognized at fair value on a recurring basis consisted of the following:


	Fair Value as of September 30, 2022
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets
Cash equivalents and restricted cash equivalents	$	139,471	$	139,471	$	-	$	-
Marketable securities:
U.S. Treasury and other government securities		291,527		276,621		14,906		-
Financial institution debt securities		325,263		-		325,263		-
Corporate debt securities		66,246		-		66,246		-
Other asset-backed securities		24,497		-		24,497		-
Total marketable securities		707,533		276,621		430,912		-
Total Assets	$	847,004	$	416,092	$	430,912	$	-

Liabilities
Contingent consideration liability - research	$	18,600	$	-	$	-	$	18,600
Total Liabilities	$	18,600	$	-	$	-	$	18,600

	Fair Value as of December 31, 2021
	Total		Level 1		Level 2		Level 3
	(In thousands)
Assets
Cash equivalents and restricted cash equivalents	$	124,636	$	124,636	$	-	$	-
Marketable securities:
U.S. Treasury and other government securities		300,477		280,085		20,392		-
Financial institution debt securities		440,416		-		440,416		-
Corporate debt securities		62,349		-		62,349		-
Other asset-backed securities		159,401		-		159,401		-
Total marketable securities		962,643		280,085		682,558		-
Total Assets	$	1,087,279	$	404,721	$	682,558	$	-

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 ended September 30, 2022
Balance at February 2, 2022 (at inception)	$	10,541
Change in fair value		8,059
Balance at September 30, 2022	$	18,600


	As of inception (February 2, 2022)		As of September 30, 2022
Discount rate	7%		12.6%
Probability of achievement	50%		80%
Projected year of achievement		2024		2023

Accrued Expenses (Tables)

9 Months Ended

Sep. 30, 2022

Payables and Accruals [Abstract]

Schedule of Accrued Expenses

Accrued expenses consisted of the following:


	September 30,		December 31,
	2022		2021
	(In thousands)
Accrued research and development	$	30,346	$	16,979
Employee compensation and benefits		17,923		20,359
Accrued legal and professional expenses		2,976		3,100
Accrued other		7,134		2,871
Total accrued expenses	$	58,379	$	43,309

Collaborations and Other Arrangements (Tables)

9 Months Ended

Sep. 30, 2022

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, 2022 and 2021 (in thousands):


	Balance at Beginning of Period		Additions		Deductions			Balance at End of Period
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

	Balance at Beginning of Period		Additions		Deductions			Balance at End of Period
Nine Months Ended September 30, 2021
Accounts receivable	$	2,130	$	5,575	$	(5,214	)	$	2,491
Contract liabilities - deferred revenue	$	73,931	$	62,900	$	(17,049	)	$	119,782

Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance

During the nine months ended September 30, 2022 and 2021, 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:	2022		2021
Amounts included in the contract liability at the beginning of the period	$	38,208	$	16,861

Rewrite Acquisition (Tables)

9 Months Ended

Sep. 30, 2022

Business Combinations [Abstract]

Summary of Transaction Price Determined and Allocated

The transaction price 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 (Tables)

9 Months Ended

Sep. 30, 2022

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,
	2022		2021		2022		2021
	(In thousands)
Research and development	$	16,383	$	9,017	$	40,736	$	18,643
General and administrative		8,832		6,393		26,038		13,805
Total	$	25,215	$	15,410	$	66,774	$	32,448

Summary of Restricted Stock Activity

The following table summarizes the Company’s RSU activity for the nine months ended September 30, 2022:


	Number of Shares			Weighted Average Grant Date Fair Value per Share
Unvested restricted stock units as of December 31, 2021		453,026		$	71.03
Granted		1,648,664			72.48
Vested		(91,843	)		66.53
Cancelled		(82,093	)		76.55
Unvested restricted stock units as of September 30, 2022		1,927,754		$	72.25

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,
	2022	2021	2022	2021
Risk-free interest rate	n/a	1.0%	1.9%	0.9%
Expected life of options	n/a	6.0 years	5.9 years	6.0 years
Expected volatility of underlying stock	n/a	75.2%	76.2%	72.7%
Expected dividend yield	n/a	0.0%	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, 2022:


	Number of Options			Weighted Average Exercise Price per Share		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
						(In years)		(In thousands)
Outstanding at December 31, 2021		6,305,156		$	43.57
Granted		391,910			86.08
Exercised		(852,913	)		16.40
Forfeited		(295,691	)		59.08
Outstanding at September 30, 2022		5,548,462		$	49.92		7.63	$	117,003
Exercisable at September 30, 2022		2,855,525		$	33.61

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 the awards issued under the 2016 Plan to employees 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,
	2022	2021	2022	2021
Risk-free interest rate	2.52%	0.05%	0.22%-2.52%	0.05%-0.09%
Expected term (in years)	0.5 years	0.5 years	0.5 years	0.5 years
Expected volatility of underlying stock	95.3%	109.2%	63.6%-95.3%	77.5%-109.2%
Expected dividend yield	0.0%	0.0%	0.0%	0.0%

Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2022

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,
	2022			2021			2022			2021
	(In thousands)
Net loss	$	(113,229	)	$	(71,644	)	$	(360,779	)	$	(186,655	)
Weighted average shares outstanding, basic and diluted		76,047			73,706			75,543			69,720
Net loss per share, basic and diluted	$	(1.49	)	$	(0.97	)	$	(4.78	)	$	(2.68	)

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,
	2022		2021
	(In thousands)
Unvested restricted stock units		1,928		443
Stock options		5,548		6,217
		7,476		6,660

Stockholders’ Equity (Tables)

9 Months Ended

Sep. 30, 2022

Equity [Abstract]

Schedule of Changes in Stockholders’ Equity

The following tables present changes in stockholders’ equity for the nine-month periods ended September 30, 2022 and 2021 (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, 2021		74,485,883	$	7	$	1,745,870	$	(2,632	)	$	(703,001	)	$	1,040,244
Issuance of common stock through at-the-market offerings, net of issuance costs of $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 marketable securities		-		-		-		(5,128	)		-			(5,128	)
Other comprehensive loss - equity method investment		-		-		-		(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 stock purchase plan		24,316		-		1,068		-			-			1,068
Equity-based compensation		-		-		23,068		-			-			23,068
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(932	)		-			(932	)
Other comprehensive loss - equity method investment		-		-		-		(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 at-the-market offerings, net of issuance costs of $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

					Additional		Accumulated Other						Total
	Common				Paid-In		Comprehensive			Accumulated			Stockholders’
	Shares		Amount		Capital		Loss			Deficit			Equity
Balance at December 31, 2020		66,234,056	$	7	$	962,173	$	1		$	(435,109	)	$	527,072
Issuance of common stock through at-the-market offerings, net of issuance costs of $52		641,709		-		45,255		-			-			45,255
Exercise of stock options		1,014,569		-		13,340		-			-			13,340
Equity-based compensation		-		-		6,424		-			-			6,424
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(13	)		-			(13	)
Net loss		-		-		-		-			(46,205	)		(46,205	)
Balance at March 31, 2021		67,890,334		7		1,027,192		(12	)		(481,314	)		545,873
Exercise of stock options		394,801		-		6,163		-			-			6,163
Vesting of restricted stock units		26,235		-		-		-			-			-
Issuance of shares under employee stock purchase plan		20,410		-		970		-			-			970
Equity-based compensation		-		-		10,614		-			-			10,614
Other comprehensive loss - unrealized loss on marketable securities		-		-		-		(1	)		-			(1	)
Net loss		-		-		-		-			(68,806	)		(68,806	)
Balance at June 30, 2021		68,331,780		7		1,044,939		(13	)		(550,120	)		494,813


Issuance of common stock through follow-on offering, net of issuance costs of $284	4,758,620		-		648,315		-			-			648,315
Exercise of stock options	1,227,067		-		20,365		-			-			20,365
Vesting of restricted stock units	24,711		-		-		-			-			-
Equity-based compensation	-		-		15,410		-			-			15,410
Other comprehensive loss	-		-		-		(161	)		-			(161	)
Net loss	-		-		-		-			(71,644	)		(71,644	)
Balance at September 30, 2021	74,342,178	$	7	$	1,729,029	$	(174	)	$	(621,764	)	$	1,107,098

Overview and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		9 Months Ended
	Feb. 02, 2022	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Market offering as other current asset		$ 26,730		$ 18,584
Common stock, shares issued		76,587,947		74,485,883
Common stock, par value		$ 0.0001		$ 0.0001
Rewrite Therapeutics Delaware Corporation Member
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Upfront consideration payable in cash	$ 45,000
Milestone payments	155,000
Cash	$ 130,000
Common stock, shares issued	25,000,000.0
Common stock, par value	$ 0.0001
IPO [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering		$ 1,887,200
At The Market Offerings [Member]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Line Items]
Proceeds from common stock offering		62,140	$ 45,255
Market offering as other current asset		$ 8,300

Marketable Securities - Summary of Available -for-sale Marketable Securities (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Amortized Cost	$ 714,727	$ 964,768
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(7,194)	(2,125)
Estimated Fair Value	707,533	962,643
U.S. Treasury and Other Government Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	295,367	301,493
Gross Unrealized Gains		0
Gross Unrealized Losses	(3,840)	(1,016)
Estimated Fair Value	291,527	300,477
Financial Institution Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	327,417	441,068
Gross Unrealized Gains		0
Gross Unrealized Losses	(2,154)	(652)
Estimated Fair Value	325,263	440,416
Corporate Debt Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	67,018	62,500
Gross Unrealized Gains		0
Gross Unrealized Losses	(772)	(151)
Estimated Fair Value	66,246	62,349
Other Asset Backed Securities [Member]
Marketable Securities [Line Items]
Amortized Cost	24,925	159,707
Gross Unrealized Gains		0
Gross Unrealized Losses	(428)	(306)
Estimated Fair Value	$ 24,497	$ 159,401

Marketable Securities - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Realized gains or losses on marketable securities	$ 0	$ 0
Investments that matured beyond five years	$ 0	$ 0
Minimum [Member]
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	1 year
Maximum [Member]
Marketable Securities [Line Items]
Available-for-sales Securities, non-current, maturity period	5 years

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, 2022	Dec. 31, 2021
Assets
Cash equivalents and restricted cash equivalents	$ 139,471	$ 124,636
Marketable securities:
Marketable securities	707,533	962,643
Total Assets	847,004	1,087,279
Liabilities
Liabilities measured at fair value	18,600
Contingent Consideration Liability - research [Member]
Liabilities
Liabilities measured at fair value	18,600
U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	291,527	300,477
Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	325,263	440,416
Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	66,246	62,349
Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	24,497	159,401
Level 1 [Member]
Assets
Cash equivalents and restricted cash equivalents	139,471	124,636
Marketable securities:
Marketable securities	276,621	280,085
Total Assets	416,092	404,721
Level 1 [Member] \| U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	276,621
Total Assets		280,085
Level 2 [Member]
Marketable securities:
Marketable securities	430,912	682,558
Total Assets	430,912	682,558
Level 2 [Member] \| U.S. Treasury and Other Government Securities [Member]
Marketable securities:
Marketable securities	14,906	20,392
Level 2 [Member] \| Financial Institution Debt Securities [Member]
Marketable securities:
Marketable securities	325,263	440,416
Level 2 [Member] \| Corporate Debt Securities [Member]
Marketable securities:
Marketable securities	66,246	62,349
Level 2 [Member] \| Other Asset Backed Securities [Member]
Marketable securities:
Marketable securities	24,497	$ 159,401
Level 3 [Member]
Liabilities
Liabilities measured at fair value	18,600
Level 3 [Member] \| Contingent Consideration Liability - research [Member]
Liabilities
Liabilities measured at fair value	$ 18,600

Fair Value Measurements - Additional information (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2022 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Abstract]
Research milestone payments	$ 25.0

Fair Value Measurements - Schedule of Change in Fair Value of the Contingent Consideration Liabilities (Detail) - USD ($) $ in Thousands		9 Months Ended
	Feb. 02, 2022	Sep. 30, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Change in fair value		$ 8,059
Balance	$ 10,541	$ 18,600
Discount rate	7.00%	12.60%
Probability of achievement	50.00%	80.00%
Projected year of achievement	2024	2023

Accrued Expenses - Schedule of Accrued Expenses (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued research and development	$ 30,346	$ 16,979
Employee compensation and benefits	17,923	20,359
Accrued legal and professional expenses	2,976	3,100
Accrued other	7,134	2,871
Total accrued expenses	$ 58,379	$ 43,309

Collaborations and Other Arrangements - Summary of Changes in Accounts Receivable and Contract Liabilities (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accounts receivable:
Accounts receivable, Balance at Beginning of Period	$ 2,031	$ 2,130
Accounts receivable, Additions	8,678	5,575
Accounts receivable, Deductions	(6,686)	(5,214)
Accounts receivable, Balance at End of Period	4,023	2,491
Contract liabilities:
Deferred revenue, Balance at Beginning of Period	127,235	73,931
Deferred revenue, Additions		62,900
Deferred revenue, Deductions	(46,739)	(17,049)
Deferred revenue, Balance at End of Period	$ 80,496	$ 119,782

Collaborations and Other Arrangements - Summary of Revenues Recognized Resulting From Changes in Contract Liability Balance (Detail) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Revenue from Contract with Customer [Abstract]
Amounts included in the contract liability at the beginning of the period	$ 38,208	$ 16,861

Collaborations and Other Arrangements - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended	78 Months Ended
	Feb. 12, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Sep. 30, 2022	Dec. 31, 2020
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Capitalized Contract Cost, Gross			$ 0		$ 0			$ 0
Collaboration revenue			13,266,000	$ 7,204,000	38,548,000	$ 20,199,000
Accounts receivable							$ 0
Deferred revenue		$ 119,782,000	80,496,000	119,782,000	80,496,000	119,782,000	127,235,000	80,496,000	$ 73,931,000
Revenue			2,900,000		8,500,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized			34,500,000		34,500,000			34,500,000
Accounts receivable			4,000,000.0		4,000,000.0		2,000,000.0	4,000,000.0
Deferred revenue			34,500,000		34,500,000		51,400,000	34,500,000
Regeneron Pharmaceuticals Inc. [Member] \| Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			3,200,000	1,100,000	6,900,000	2,100,000
Regeneron Pharmaceuticals Inc. [Member] \| Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions								145,000,000.0
Collaboration revenue			6,500,000	6,700,000	$ 18,600,000	18,700,000		167,600,000
Aggregate transaction price remaining to be recognized, period					Through September 30, 2022
Payments due			4,000,000.0	2,100,000	$ 8,700	3,900,000
Regeneron Pharmaceuticals Inc. [Member] \| Regeneron Agreement [Member] \| Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue								39,700,000
Novartis [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		$ 300,000
Strategic collaboration agreement amended date					2018-12
One time payment to novartis							10,000,000.0
Novartis [Member] \| AvenCell Co Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue			0		$ 0		0	0
ONK Therapeutics [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development And Commercial Milestone Payment To be Received	$ 184,000,000
Kyverna Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			0		0		0	0
Deferred revenue			2,700,000		2,700,000		7,000,000.0	2,700,000
Revenue			2,300,000		4,300,000
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			0	0	0	0
Accounts receivable			0		0			0
Deferred revenue			14,800,000		14,800,000		14,800,000	14,800,000
AvenCell [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions			2,900,000	62,500	8,500,000	62,500
Collaboration revenue			5,700,000	125,000.0	17,100,000	125,000.0
Accounts receivable			0		0			0
Deferred revenue			28,500,000		28,500,000		54,100,000	$ 28,500,000
AvenCell [Member] \| AvenCell Co Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 1,300,000	$ 200,000	$ 1,400,000	$ 200,000
Accounts receivable							$ 100,000

Equity-Method Investment and Other Investments - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Oct. 31, 2021	Jul. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Schedule of Equity Method Investments [Line Items]
Investments in and Advances to Affiliates, at Fair Value, Gross Reductions			$ 2,600		$ 9,500
Loss from equity method investment			(1,834)	$ 0	(7,831)	$ 0
Equity method investment			40,102		40,102		$ 58,131
Preferred Stock Purchase Agreement [Member] \| Joint Venture Aven Cell [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 Aven Cell [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
Loss from equity method investment			2,900		8,500
Equity method investment			40,100		40,100
AvenCell [Member] \| Measurement Input, Option Volatility [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		76.00%
AvenCell [Member] \| Measurement Input Option Subsequent Financing [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		75.00%
AvenCell [Member] \| Measurement Input, Discount for Lack of Marketability [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage		11.00%
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
Sparing Vision [Member] \| Measurement Input, Option Volatility [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage	90.00%
Sparing Vision [Member] \| Measurement Input Option Rate Of Return [Member]
Schedule of Equity Method Investments [Line Items]
Equity securities measurement input, percentage	65.00%
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 - Additional Information (Detail) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Feb. 02, 2022	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021
Business Acquisition [Line Items]
Research and development		$ 96,651	$ 60,486	$ 319,945	$ 158,646
Common stock, shares issued		76,587,947		76,587,947		74,485,883
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	25,000,000.0
Liability for milestone payment	$ 10,500			$ 0

Rewrite Acquisition - Summary of Transaction Price Determined and Allocated (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2022 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 (Detail) $ in Thousands		1 Months Ended			9 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Feb. 28, 2022 USD ($) ft²	Jun. 30, 2022 USD ($) ft²	Feb. 28, 2022 USD ($) ft²	Jan. 31, 2022 USD ($) ft²	Sep. 30, 2022 USD ($) ft²	Jan. 01, 2023 USD ($)	Dec. 31, 2021 USD ($)
Lessee Lease Description [Line Items]
Operating lease right-of-use assets					$ 101,290		$ 79,143
Prepaid lease payments					$ 500
730 Main Lease [Member]
Lessee Lease Description [Line Items]
Area of space leased \| ft²					38,000
Operating lease, description					In January 2022, the Company entered into an agreement to lease approximately 38,000 square feet of office and laboratory space at 730 Main Street, Cambridge, Massachusetts under an operating lease agreement (the “730 Main Lease”). The initial term of the 730 Main Lease is
Term of lease				10 years
Base rent per square foot for first year \| ft²				130.00
Letter of credit				$ 2,400
Operating lease, options to extend					the Company has the option to extend the 730 Main Lease for one five-year term.
Percentage of Annual Increase					3.00%
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 the second half of 2024 for an
Term of lease	12 years		12 years
Base rent per square foot for first year \| ft²			73.50
Letter of credit	$ 2,600		$ 2,600
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					3.00%
840 Winter Street Lease [Member] \| forecast Member
Lessee Lease Description [Line Items]
Letter of credit						$ 6,000
MemorialDrive640Member
Lessee Lease Description [Line Items]
Area of space leased \| ft²		62,000
Operating lease, description		In June 2022, the Company entered into an agreement to lease approximately 62,000 square feet of office and laboratory space located at 640 Memorial Drive, Cambridge, Massachusetts under an operating lease agreement (the “640 Memorial Drive Lease”). The term of the lease is five years, ending in August 2027. The Company does not have an option to extend the 640 Memorial Drive Lease. The base rent under the 640 Memorial Drive Lease is approximately $97 per square foot per year during the first year of the term, which is subject to scheduled 4% annual increases, plus certain operating expenses and taxes. In September 2022 the Company determined, in accordance with ASC 842, that the commencement date for the lease had been met as the lessor had made the space available for the Company's use
Term of lease		5 years
Base rent per square foot for first year \| ft²		0.97
Operating lease right-of-use assets					$ 30,700
Operating lease, liability					$ 30,200
Incremental borrowing rate					7.99%
Letter of credit					$ 1,800
cost of tenant improvements		$ 1,200
Operating lease, options to extend					The Company does not have an option to extend the 640 Memorial Drive Lease.
Percentage of Annual Increase					4.00%

Equity-Based Compensation - Schedule of Equity-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 25,215	$ 15,410	$ 66,774	$ 32,448
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	16,383	9,017	40,736	18,643
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Equity-based compensation expense	$ 8,832	$ 6,393	$ 26,038	$ 13,805

Equity-Based Compensation - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		9 Months Ended
	Mar. 31, 2022 $ / shares shares	May 31, 2016	Sep. 30, 2022 USD ($) $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Sep. 30, 2022 USD ($) Tranche $ / shares shares	Sep. 30, 2021 USD ($) $ / shares shares	Dec. 31, 2021 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares issued			76,587,947		76,587,947		74,485,883
Weighted Average Grant Date Fair Value per Share, Granted \| $ / shares			$ 55.59	$ 171.65	$ 72.48	$ 63.13
Total fair value amount, Vested \| $			$ 100	$ 3,700	$ 8,000	$ 5,700
Number of Shares, Granted			0		1,648,664
Number of Shares, Vested					(91,843)
Risk-free interest rate				1.00%	1.90%	0.90%
Number of tranches \| Tranche					2
Expected dividend yield				0.00%	0.00%	0.00%
Expected volatility				75.20%	76.20%	72.70%
Expected term				6 years	5 years 10 months 24 days	6 years
Equity-based compensation expense \| $			$ 25,215	$ 15,410	$ 66,774	$ 32,448
Weighted average period of unrecognized compensation costs					2 years 6 months
Weighted average grant date fair value per share \| $ / shares				$ 105.17	$ 57.23	$ 50.73
Total intrinsic value of stock options exercised \| $			1,400	$ 171,300	$ 41,800	$ 255,800
Unrecognized compensation cost related to stock options \| $			106,500		106,500
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized equity-based compensation expense related to restricted stock \| $			$ 110,400		$ 110,400
Weighted average period of unrecognized compensation costs					2 years 3 months 18 days
RSUs [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	$ 79.85
Number of Shares, Granted	794,424
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	$ 126.49
Number of Shares, Granted	55,144
Risk-free interest rate	1.44%
Expected dividend yield	0.00%
Expected volatility	82.53%
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
Equity-based compensation expense \| $					$ 1,200
2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining vesting period					3 years
Description of stock options granted under the Plan					Stock options granted under the 2015 Plan generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years, unless they contain specific performance-based vesting provisions. The maximum term of stock options granted under the 2015 Plan is ten years.Effective July 1, 2022, the Company adopted a retirement policy for equity awards granted to all employees other than the Company’s CEO (the “Policy”). The Policy applies to all equity awards granted after the date of adoption to employees who meet certain retirement eligibility criteria set forth in the Policy (the “Retirees”). Pursuant to the terms of the 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.
Shares available for future issuance			3,565,012		3,565,012
Percentage of cumulative increase in number of shares for future issuance					4.00%
2015 Plan [Member] \| First Anniversary of Original Vesting Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vest percentage on the first anniversary					25.00%
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		85.00%
Shares available for future issuance			1,272,886		1,272,886
Common stock, shares issued			24,316	20,410	24,316	20,410
Weighted Average Grant Date Fair Value per Share, Granted \| $ / shares					$ 44.00	$ 47.52
Risk-free interest rate			2.52%	0.05%
Expected dividend yield			0.00%	0.00%	0.00%	0.00%
Expected volatility			95.30%	109.20%
Expected term			6 months	6 months	6 months	6 months
Maximum [Member] \| 2015 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options granted					10 years
Maximum [Member] \| 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 - Summary of Restricted Stock Activity (Detail) - $ / shares	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-Based Payment Arrangement [Abstract]
Number of Shares, Unvested, Beginning balance			453,026
Number of Shares, Granted	0		1,648,664
Number of Shares, Vested			(91,843)
Number of Shares, Cancelled			(82,093)
Number of Shares, Unvested, Ending balance	1,927,754		1,927,754
Weighted Average Grant Date Fair Value per Share, Unvested, Beginning balance			$ 71.03
Weighted Average Grant Date Fair Value per Share, Granted	$ 55.59	$ 171.65	72.48	$ 63.13
Weighted Average Grant Date Fair Value per Share, Vested			66.53
Weighted Average Grant Date Fair Value per Share, Cancelled			76.55
Weighted Average Grant Date Fair Value per Share, Unvested, Ending balance	$ 72.25		$ 72.25

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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate		1.00%	1.90%	0.90%
Expected term		6 years	5 years 10 months 24 days	6 years
Expected volatility of underlying stock		75.20%	76.20%	72.70%
Expected dividend yield		0.00%	0.00%	0.00%
2016 Employee Stock Purchase Plan [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Risk-free interest rate	2.52%	0.05%
Risk-free interest rate, Minimum			0.22%	0.05%
Risk-free interest rate , Maximum			2.52%	0.09%
Expected term	6 months	6 months	6 months	6 months
Expected volatility of underlying stock	95.30%	109.20%
Expected volatility of underlying stock, Minimum			63.60%	77.50%
Expected volatility of underlying stock, Maximum			95.30%	109.20%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%

Equity-Based Compensation - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2022
Share-Based Payment Arrangement [Abstract]
Number of Options, Outstanding, Beginning Balance	6,305,156
Number of options, Granted	391,910
Number of options, Exercised	(852,913)
Number of options, Forfeited	(295,691)
Number of Options, Outstanding, Ending Balance	5,548,462
Number of Options, Exercisable	2,855,525
Weighted Average Exercise Price per Share, Outstanding, Beginning Balance	$ 43.57
Weighted Average Exercise Price per Share, Granted	86.08
Weighted Average Exercise Price per Share, Exercised	16.40
Weighted Average Exercise Price per Share, Forfeited	59.08
Weighted Average Exercise Price per Share, Outstanding, Ending Balance	49.92
Weighted Average Exercise Price per Share, Exercisable	$ 33.61
Weighted Average Remaining Contractual Term, Outstanding	7 years 7 months 17 days
Aggregate Intrinsic Value, Outstanding	$ 117,003

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, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Earnings Per Share [Abstract]
Net loss	$ (113,229)	$ (100,678)	$ (146,872)	$ (71,644)	$ (68,806)	$ (46,205)	$ (360,779)	$ (186,655)
Weighted average shares outstanding, basic	76,047			73,706			75,543	69,720
Weighted average shares outstanding, diluted	76,047			73,706			75,543	69,720
Net Loss Per Share, Basic	$ (1.49)			$ (0.97)			$ (4.78)	$ (2.68)
Net Loss Per Share, Diluted	$ (1.49)			$ (0.97)			$ (4.78)	$ (2.68)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 65
-Paragraph 1
-Subparagraph (e)(4)
-URI https://asc.fasb.org/extlink&oid=126732423&loc=SL123482106-238011

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=124431687&loc=d3e22583-107794

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=126958026&loc=d3e1448-109256

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 4
-URI https://asc.fasb.org/extlink&oid=124431687&loc=d3e22595-107794

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 250
-SubTopic 10
-Section 50
-Paragraph 11
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=124431687&loc=d3e22694-107794

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 7
-URI https://asc.fasb.org/extlink&oid=126958026&loc=d3e1337-109256

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 65
-Paragraph 1
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=126732423&loc=SL123482106-238011

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 55
-Paragraph 52
-URI https://asc.fasb.org/extlink&oid=128363288&loc=d3e4984-109258

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 220
-Section S99
-Paragraph 1
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The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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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, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Potential dilutive securities excluded from computation of diluted net loss per common share	7,476	6,660	7,476	6,660
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	1,928	443	1,928	443
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	5,548	6,217	5,548	6,217

Stockholders' Equity - Schedule of Changes in Stockholders Equity (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Class Of Stock [Line Items]
Beginning balance	$ 880,547	$ 953,754	$ 1,040,244	$ 494,813	$ 545,873	$ 527,072	$ 1,040,244	$ 527,072
Beginning balance, shares			74,485,883				74,485,883
Exercise of stock options	722	4,827	$ 8,435	20,365	6,163	13,340
Exercise of stock options, shares							852,913
Issuance of shares under employee stock purchase plan		1,068			970
Equity-based compensation	25,215	23,068	18,491	15,410	10,614	6,424
Other comprehensive loss				(161)
Other comprehensive loss - unrealized loss on marketable securities	991	(932)	(5,128)		(1)	(13)
Other comprehensive loss from equity method investment	(805)	(560)	(302)	0			$ (1,667)	0
Net loss	(113,229)	(100,678)	(146,872)	(71,644)	(68,806)	(46,205)	(360,779)	(186,655)
Ending balance	$ 824,951	880,547	953,754	1,107,098	494,813	545,873	$ 824,951	1,107,098
Ending balance, shares	76,587,947						76,587,947
Follow-on Offering [Member]
Class Of Stock [Line Items]
Issuance of common stock				648,315
At The Market Offerings [Member]
Class Of Stock [Line Items]
Issuance of common stock	$ 31,510		38,886			45,255
Common Stock [Member]
Class Of Stock [Line Items]
Beginning balance	$ 8	$ 8	$ 7	$ 7	$ 7	$ 7	$ 7	$ 7
Beginning balance, shares	76,000,745	75,624,167	74,485,883	68,331,780	67,890,334	66,234,056	74,485,883	66,234,056
Exercise of stock options, shares	33,336	315,747	503,830	1,227,067	394,801	1,014,569
Vesting of restricted stock units, shares	662	36,515	54,666	24,711	26,235
Issuance of shares under employee stock purchase plan, shares		24,316			20,410
Ending balance	$ 8	$ 8	$ 8	$ 7	$ 7	$ 7	$ 8	$ 7
Ending balance, shares	76,587,947	76,000,745	75,624,167	74,342,178	68,331,780	67,890,334	76,587,947	74,342,178
Common Stock [Member] \| Follow-on Offering [Member]
Class Of Stock [Line Items]
Number of stock additionally invested				4,758,620
Common Stock [Member] \| At The Market Offerings [Member]
Class Of Stock [Line Items]
Issuance of common stock			$ 1
Number of stock additionally invested	553,204		579,788			641,709
Additional Paid-In Capital [Member]
Class Of Stock [Line Items]
Beginning balance	$ 1,840,644	$ 1,811,681	$ 1,745,870	$ 1,044,939	$ 1,027,192	$ 962,173	$ 1,745,870	$ 962,173
Exercise of stock options	722	4,827	8,435	20,365	6,163	13,340
Issuance of shares under employee stock purchase plan		1,068			970
Equity-based compensation	25,215	23,068	18,491	15,410	10,614	6,424
Ending balance	1,898,091	1,840,644	1,811,681	1,729,029	1,044,939	1,027,192	1,898,091	1,729,029
Additional Paid-In Capital [Member] \| Follow-on Offering [Member]
Class Of Stock [Line Items]
Issuance of common stock				648,315
Additional Paid-In Capital [Member] \| At The Market Offerings [Member]
Class Of Stock [Line Items]
Issuance of common stock	31,510		38,885			45,255
Accumulated Other Comprehensive Loss [Member]
Class Of Stock [Line Items]
Beginning balance	(9,554)	(8,062)	(2,632)	(13)	(12)	1	(2,632)	1
Other comprehensive loss				(161)
Other comprehensive loss - unrealized loss on marketable securities	991	(932)	(5,128)		(1)	(13)
Other comprehensive loss from equity method investment	(805)	(560)	(302)
Ending balance	(9,368)	(9,554)	(8,062)	(174)	(13)	(12)	(9,368)	(174)
Accumulated Deficit [Member]
Class Of Stock [Line Items]
Beginning balance	(950,551)	(849,873)	(703,001)	(550,120)	(481,314)	(435,109)	(703,001)	(435,109)
Net loss	(113,229)	(100,678)	(146,872)	(71,644)	(68,806)	(46,205)
Ending balance	$ (1,063,780)	$ (950,551)	$ (849,873)	$ (621,764)	$ (550,120)	$ (481,314)	$ (1,063,780)	$ (621,764)

Stockholders' Equity - Schedule of Changes in Stockholders Equity (Parenthetical) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Mar. 31, 2021
Class Of Stock [Line Items]
Stock issuance cost, net	$ 54	$ 164	$ 284	$ 52

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands			1 Months Ended		9 Months Ended
	Jul. 02, 2021	Jun. 29, 2021	Mar. 31, 2022	Aug. 31, 2019	Sep. 30, 2022	Sep. 30, 2021
Follow-on Offering [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering					$ 0	$ 648,315
2019 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering					$ 38,900
Percentage of gross proceeds from common stock as sales agent cash commission				3.00%
Stock Issued During Period, Shares, New Issues					579,788
Common stock price per share					$ 69.43
2019 Sales Agreement [Member] \| General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees					$ 200
2019 Sales Agreement [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering				$ 150,000
2022 Sales Agreement [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering					$ 31,500
Percentage of gross proceeds from common stock as sales agent cash commission			3.00%
Stock Issued During Period, Shares, New Issues					553,204
Common stock price per share					$ 58.82
Proceeds From Sale of Marketable Securities					$ 8,300
Proceeds from common stock offering					367,500
2022 Sales Agreement [Member] \| General and Administrative Expenses [Member]
Class Of Stock [Line Items]
Legal accounting and other fees					$ 100
2022 Sales Agreement [Member] \| Maximum [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering			$ 400,000
Underwriting Agreement [Member] \| Follow-on Offering [Member]
Class Of Stock [Line Items]
Proceeds from common stock offering	$ 648,300
Stock Issued During Period, Shares, New Issues		4,758,620
Common stock price per share		$ 145.00
Underwriting discounts and estimated offering costs	$ 41,700

Related Party Transaction - Additional information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Dec. 31, 2021	Dec. 31, 2020
Related Party Transaction [Line Items]
Revenue	$ 2,900		$ 8,500
Deferred revenue	80,496	$ 119,782	80,496	$ 119,782	$ 127,235	$ 73,931
Deferred revenue current	54,818		54,818		63,759
Deferred revenue non-current	25,678		25,678		63,476
Investment	36,989		36,989		$ 29,558
Collaboration revenue	13,266	7,204	38,548	20,199
AvenCell Co Co Agreement [Member]
Related Party Transaction [Line Items]
Deferred revenue current	28,500		$ 28,500
Avencelllca
Related Party Transaction [Line Items]
Revenue	$ 5,700	$ 125,000		$ 62,500
Avencelllca \| Joint Venture AvenCell [Member]
Related Party Transaction [Line Items]
Equity method investment, ownership percentage	33.33%		33.33%
Avencelllca \| AvenCell Co Co Agreement [Member]
Related Party Transaction [Line Items]
Deferred revenue	$ 8,500		$ 8,500
Avencellcoco
Related Party Transaction [Line Items]
Revenue			17,100
Contra Revenue	$ 1,300		$ 1,400

Subsequent Events - Additional Information (Detail) - USD ($)		9 Months Ended
	Oct. 27, 2022	Sep. 30, 2022
Other Current Assets [Member]
Subsequent Event [Line Items]
Proceeds from common stock offering		$ 8,300
2022 Sales Agreement [Member]
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues		553,204
Common stock price per share		$ 58.82
Proceeds from common stock offering		$ 31,500,000
Subsequent Event [Member] \| 2022 Sales Agreement [Member]
Subsequent Event [Line Items]
Stock Issued During Period, Shares, New Issues	1,864,527
Common stock price per share	$ 59.26
Proceeds from common stock offering	$ 107,200,000