Codiak BioSciences (CDAKQ) 10-K 10 Mar 22 2021 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Mar. 04, 2022	Jun. 30, 2021
Cover [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	FY
Entity Registrant Name	CODIAK BIOSCIENCES, INC.
Entity Central Index Key	0001659352
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Common Stock, Shares Outstanding		22,493,867
Entity Public Float			$ 412,718,249
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Trading Symbol	CDAK
Security Exchange Name	NASDAQ
Entity File Number	001-39615
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	47-4926530
Entity Address, Address Line One	35 Cambridge Park Drive
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02140
City Area Code	617
Local Phone Number	949-4100
Document Annual Report	true
Document Transition Report	false
ICFR Auditor Attestation Flag	false
Documents Incorporated by Reference	DOCUMENTS INCORPORATED BY REFERENCE The registrant intends to file a definitive proxy statement pursuant to Regulation 14A relating to the 2022 Annual Meeting of Stockholders within 120 days of the end of the registrant’s fiscal year ended December 31, 2021. Portions of such definitive proxy statement are incorporated by reference into Part III of this Annual Report on Form 10-K to the extent stated herein.
Auditor Firm ID	42
Auditor Name	Ernst & Young LLP
Auditor Location	Boston, Massachusetts

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 76,938	$ 88,915
Prepaid manufacturing services	7,315	101
Prepaid expenses and other current assets	5,918	4,742
Total current assets	90,171	93,758
Property and equipment, net	23,479	31,410
Restricted cash	4,170	4,170
Operating right-of-use assets	21,957	22,003
Prepaid manufacturing services, net of current portion	31,893
Total assets	171,670	151,341
Current liabilities:
Accounts payable	1,838	2,018
Accrued expenses	9,703	8,870
Deferred revenue	12,963	5,281
Operating lease liabilities	2,661	1,482
Total current liabilities	27,165	17,651
Long-term liabilities:
Deferred revenue, net of current portion	30,686	57,416
Note payable, net of discount	25,430	24,960
Operating lease liabilities, net of current portion	34,884	36,540
Other long-term liabilities		207
Total liabilities	118,165	136,774
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock, $0.0001 par value; 150,000,000 shares authorized as of December 31, 2021 and December 31, 2020; 22,383,830 and 18,787,579 shares issued and outstanding as of December 31, 2021 and December 31, 2020, respectively	2	2
Additional paid-in capital	378,750	302,655
Accumulated deficit	(325,247)	(288,090)
Total stockholders' equity	53,505	14,567
Total liabilities and stockholders' equity	$ 171,670	$ 151,341

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	22,383,830	18,787,579
Common stock, shares outstanding	22,383,830	18,787,579

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Revenue:
Collaboration revenue	$ 22,935,000	$ 2,915,000
Total revenue	22,935,000	2,915,000
Operating expenses:
Research and development	64,855,000	73,981,000
General and administrative	27,629,000	19,852,000
Total operating expenses	92,484,000	93,833,000
Loss from operations	(69,549,000)	(90,918,000)
Other income (expense):
Gain on disposition	33,286,000
Other income	1,780,000	906,000
Interest income	22,000	253,000
Interest expense	(2,696,000)	(1,906,000)
Total other income (expense), net	32,392,000	(747,000)
Net loss	(37,157,000)	(91,665,000)
Cumulative dividends on redeemable convertible preferred stock		(10,831,000)
Net loss attributable to common stockholders	$ (37,157,000)	$ (102,496,000)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.70)	$ (16.18)
Weighted average common shares outstanding, basic and diluted	21,794,546	6,332,841
Comprehensive loss:
Net loss	$ (37,157,000)	$ (91,665,000)
Other comprehensive loss:
Unrealized loss on investments, net of tax of $0		(43,000)
Total other comprehensive loss	0	(43,000)
Comprehensive loss	$ (37,157,000)	$ (91,708,000)

CONSOLIDATED STATEMENTS OF OP_2

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Statement [Abstract]
Unrealized loss on investments, tax	$ 0	$ 0

CONSOLIDATED STATEMENTS OF REDE

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Thousands	Total	Series A Redeemable Convertible Preferred Stock	Series B Redeemable Convertible Preferred Stock	Series C Redeemable Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ (192,833)					$ 2	$ 43	$ (192,878)
Temporary equity, Beginning balance, shares at Dec. 31, 2019		33,200,000	20,520,828	20,204,079
Temporary equity, Beginning balance at Dec. 31, 2019		$ 44,169	$ 81,108	$ 89,507
Beginning balance, shares at Dec. 31, 2019					2,997,040
Issuance of Series B redeemable convertible preferred stock in conjunction with sponsored research agreement, shares			62,500
Exercise of options to purchase common stock	232					232
Exercise of options to purchase common stock, shares					47,592
Issuance of common stock in connection with license agreement	2,660					2,660
Issuance of common stock in connection with license agreement, shares					177,318
Accretion of redeemable convertible preferred stock to redemption value	(10,784)					(7,237)		(3,547)
Temporary equity, Accretion of preferred stock to redemption value		$ 2,097	$ 3,853	$ 4,834
Stock-based compensation	7,080					7,080
Unrealized loss on investments	(43)						$ (43)
Temporary Equity, Conversion of redeemable convertible preferred stock into common stock upon initial public offering, shares		(33,200,000)	(20,583,328)	(20,204,079)
Temporary Equity, Conversion of redeemable convertible preferred stock into common stock upon initial public offering		$ (46,266)	$ (84,961)	$ (94,341)
Conversion of redeemable convertible preferred stock into common stock upon initial public offering	225,568				$ 1	225,567
Conversion of redeemable convertible preferred stock into common stock upon initial public offering, shares					10,065,629
Issuance of common stock upon initial public offering/public offering, net of issuance costs	74,352				$ 1	74,351
Issuance of common stock upon initial public offering/public offering, net of issuance costs, shares					5,500,000
Net loss	(91,665)							(91,665)
Ending balance at Dec. 31, 2020	$ 14,567				$ 2	302,655		(288,090)
Temporary equity, Ending balance, shares at Dec. 31, 2020	0
Ending balance, shares at Dec. 31, 2020					18,787,579
Exercise of options to purchase common stock	$ 3,737					3,737
Exercise of options to purchase common stock, shares	433,751				433,751
Stock-based compensation	$ 10,677					10,677
Issuance of common stock upon initial public offering/public offering, net of issuance costs	61,681					61,681
Issuance of common stock upon initial public offering/public offering, net of issuance costs, shares					3,162,500
Net loss	(37,157)							(37,157)
Ending balance at Dec. 31, 2021	$ 53,505				$ 2	$ 378,750		$ (325,247)
Temporary equity, Ending balance, shares at Dec. 31, 2021	0
Ending balance, shares at Dec. 31, 2021					22,383,830

CONSOLIDATED STATEMENTS OF RE_2

CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Statement Of Stockholders Equity [Abstract]
Issuance of common stock upon public offering, net of issuance costs	$ 560	$ 2,373

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net loss	$ (37,157)	$ (91,665)
Adjustments to reconcile net loss to net cash from operating activities:
Stock-based compensation expense	10,142	7,080
Gain on disposition	(33,286)
Loss on disposal of property and equipment	42
Non-cash interest expense	470	388
Fair value of common stock earned in connection with license agreement		2,660
Depreciation and amortization expense	5,341	4,363
Accretion of investments		(40)
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,238)	(117)
Prepaid manufacturing services	63	(101)
Operating right-of-use assets	1,080	1,183
Other non-current assets		48
Accounts payable	96	(378)
Accrued expenses	862	(3,985)
Deferred revenue	(19,048)	7,085
Operating lease liabilities	(1,511)	10,118
Net cash used in operating activities	(74,144)	(63,361)
Cash flows from investing activities:
Purchases of property and equipment	(3,245)	(21,052)
Maturities of investments		73,062
Net cash (used in) provided by investing activities	(3,245)	52,010
Cash flows from financing activities:
Proceeds from long-term debt, net of issuance costs		15,000
Proceeds from exercise of common stock options	3,738	232
Proceeds from public offering of common stock, net of issuance costs	61,674	74,351
Net cash provided by financing activities	65,412	89,583
Net (decrease) increase in cash, cash equivalents and restricted cash	(11,977)	78,232
Cash, cash equivalents and restricted cash, beginning of period	93,085	14,853
Cash, cash equivalents and restricted cash, end of period	81,108	93,085
Supplemental disclosures:
Cash paid for interest	2,242	1,403
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued expenses	152	1,122
Deferred offering costs included in accrued expenses	98	165
Accretion of redeemable convertible preferred stock to redemption value		10,784
Operating right-of-use assets obtained in exchange for operating lease liabilities	1,034	23,186
Conversion of convertible preferred stock into common stock		225,568
Reconciliation to amounts within the condensed consolidated balance sheets
Cash and cash equivalents	76,938	88,915
Restricted cash	4,170	4,170
Cash, cash equivalents and restricted cash at end of period	$ 81,108	$ 93,085

Nature of the Business

Nature of the Business	12 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of the Business	1. Nature of the business Codiak BioSciences, Inc. (collectively, with its consolidated subsidiaries, any of Codiak, we, us, or the Company) was incorporated in Delaware on June 12, 2015 and is headquartered in Cambridge, Massachusetts. Codiak is a clinical-stage biopharmaceutical company focused on pioneering the development of exosome-based therapeutics, a new class of medicines with the potential to transform the treatment of a wide spectrum of diseases with high unmet medical need. Exosomes have evolved as intercellular transfer mechanisms for complex, biologically active macromolecules and have emerged in recent years as a compelling potential drug delivery vehicle. By leveraging Codiak’s deep understanding of exosome biology, the Company has developed its engineering and manufacturing platform (the engEx Platform), to expand upon the innate properties of exosomes to design, engineer and manufacture novel exosome therapeutics. Codiak has utilized its engEx Platform to generate a deep pipeline of engineered exosomes (engEx exosomes) aimed at treating a broad range of diseases, including oncology, neuro-oncology, and infectious disease and rare disease. In September 2020, Codiak initiated clinical trials for its two lead product candidates, exoSTING and exoIL-12, which are being developed to address solid tumors. In November 2021, Codiak announced that the U.S. Food and Drug Administration, or FDA, cleared its Investigational New Drug Application (IND) for exoASO-STAT6. This will be Codiak’s first systemically delivered exosome therapeutic candidate. To its knowledge, exoSTING,exoIL-12 and exoASO-STAT6 are the first engineered exosomes to enter clinical development. Since its inception, the Company has devoted substantially all of its resources to its research and development efforts, including activities to develop its engEx Platform, advance engEx product candidates into clinical trials, perform preclinical research to identify potential engEx product candidates, to perform process development to refine Codiak’s exosome engineering and manufacturing processes, and to provide general and administrative support for these operations. The Company has primarily funded its operations with proceeds from the sales of common stock, redeemable convertible preferred stock, collaborative and research arrangements with Jazz and Sarepta and its Loan and Security agreement with Hercules Capital, Inc. (Hercules). As of December 31, 2021 , the Company has raised an aggregate of $ 168.2 million through the issuance of its redeemable convertible preferred stock and convertible debt, net of issuance costs, $ 24.6 million from its term loan facility with Hercules, net of issuance costs, and received $ 66.0 million in payments from its collaborations with Jazz and Sarepta. On October 16, 2020, the Company completed its initial public offering (IPO), pursuant to which it issued and sold 5,500,000 shares of its common stock at a public offering price of $ 15.00 per share, resulting in net proceeds of $ 74.4 million, after deducting underwriting discounts and commissions and other offering expenses. In addition, on February 17, 2021, the Company completed a follow-on public offering, pursuant to which it issued and sold 3,162,500 shares of its common stock (inclusive of the exercise of the underwriter’s option to purchase 412,500 additional shares of common stock) at a public offering price of $ 21.00 per share, resulting in aggregate net proceeds of $ 61.7 million, after deducting underwriting discounts and commissions and other offering expenses. The Company has incurred significant operating losses and negative cash flows from operations since inception. The Company expects to continue to incur significant expenses and operating losses for the foreseeable future. In addition, the Company anticipates that its expenses will increase significantly in connection with ongoing activities to support its engEx Platform development, drug discovery and preclinical and clinical development, in addition to creating a portfolio of intellectual property and providing administrative support. The Company does not expect to generate significant revenue from sales of its engEx product candidates unless and until clinical development has been successfully completed and regulatory approval is obtained. If the Company obtains regulatory approval for any of its investigational products, it expects to incur significant commercialization expenses. As a result, the Company will need substantial additional funding to support its continued operations and growth strategy. Until such a time as the Company can generate significant revenue from product sales, if ever, the Company expects to finance its operations through the sale of equity, debt financings or other capital sources, including collaborations with other companies or other strategic transactions. The Company may be unable to raise additional funds or enter into such other agreements on favorable terms, or at all. If the Company fails to raise capital or enter into such agreements as, and when, needed, the Company may have to significantly delay, scale back or discontinue the development and commercialization of one or more of its product candidates or delay its pursuit of potential in-licenses or acquisitions. The Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the consolidated financial statements are issued. The Company expects that its cash and cash equivalents as of December 31, 2021 of $ 76.9 million, will be insufficient to allow the Company to fund its current operating plan through at least the next twelve months from the issuance of these financial statements. These conditions raise substantial doubt about the Company’s ability to continue as a going concern for a period of at least one year from the date these financial statements are issued. Accordingly, the Company will be required to raise additional funds through a public equity financing, establish collaborations with, or license its technology to other companies, seek alternative means of financial support or both, in order to continue to fund its operations in the future. There can be no assurance, however, that additional fund raising will be successful and available on terms acceptable to the Company, or at all. If the Company is unable to raise capital when needed or on attractive terms, it may be forced to delay, reduce or eliminate certain costs related to its operations and research and development programs. The Company is subject to those risks associated with any biopharmaceutical company that has substantial expenditures for research and development. There can be no assurance that the Company’s research and development projects will be successful, that products developed will obtain necessary regulatory approval, or that any approved product will be commercially viable. In addition, the Company operates in an environment of rapid technological change and is largely dependent on the services of its employees and consultants. If the Company fails to become profitable or is unable to sustain profitability on a continuing basis, then it may be unable to continue its operations at planned levels and be forced to reduce its operations.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of significant accounting policies Basis of presentation and principles of consolidation The Company's consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP). Any reference in these notes to applicable guidance is meant to refer to the authoritative accounting principles generally accepted in the United States as found in the Accounting Standard Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Codiak Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation. Use of estimates We have made estimates and judgments affecting the amounts reported in our consolidated financial statements and the accompanying notes. On an ongoing basis, we evaluate our estimates, including critical accounting policies or estimates related to revenue recognition, stock-based compensation, accrued expenses, leases, gain upon derecognition, contingent consideration and the long-lived lives of useful assets. We base our estimates on historical experience and various relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. The actual results that we experience may differ materially from our estimates. Significant estimates relied upon in preparing these financial statements include, among others, those related to the fair value of equity awards, revenue recognition, accrued expenses, leases, gain upon derecognition, contingent consideration, income taxes, and long-lived lives of useful assets. Segments The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and allocating resources. All of the Company’s long-lived assets are held in the United States. Disposition of Business The Company accounts for the derecognition of a group of assets that is a business in transactions with noncustomers in accordance with ASC 810-10-40. The Company measures the gain or loss upon derecognition as the difference between: (i) aggregate fair value of any consideration received and (ii) carrying amount of the group of assets, net of transaction and other costs directly attributable to the transaction. Gains and losses are recognized as of the date the Company ceases to have a controlling financial interest in the associated group of assets. Consideration received, including contingent consideration, is initially measured at fair value. Contingent consideration is subsequently remeasured by recognizing increases using a gain contingency approach and impairments based on the loss contingency model. Both the fair value of the consideration received and any potential future contingent gains contain unobservable inputs, whereby expected future cash flows are discounted using a rate that includes assumptions regarding an entity’s average cost of debt and equity, incorporates expected future cash flows based on internal business plans, and applies certain assumptions about risk and uncertainties. Cash, cash equivalents and restricted cash The Company considers all highly liquid investments purchased with original final maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents comprises money market accounts invested in US Treasury securities. Restricted cash is composed of letters of credit held as collateral related to the Company’s lease arrangements. Restricted cash is classified as either current or non-current based on the term of the underlying lease agreement. Investments The Company classifies all of its investments as available-for-sale securities. The Company’s investments are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive (loss) income, which is a separate component of stockholders’ equity (deficit). The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net within the consolidated statements of operations and comprehensive loss. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary”, the Company reduces the investment to fair value through a charge to the consolidated statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented. The Company classifies its available-for-sale investments as current assets on the consolidated balance sheets if they mature within one year from the balance sheet date. Those investments with maturities greater than 12 months would be considered non-current. Investments with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets. Deferred offering costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. Such costs are classified in prepaid expenses and other current assets in the accompanying consolidated balance sheets. After the consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital or the associated preferred stock account, as applicable. In the event the offering is terminated, all capitalized deferred offering costs are expensed. Deferred offering costs as of December 31, 2021 were $ 0.2 million in connection with the Company's shelf registration and “at-the-market” offering facility. Deferred offering costs as of December 31, 2020 were $ 0.2 million in connection with the follow-on equity funding completed in February 2021. Concentrations of credit risk and significant suppliers and license agreements Financial instruments that potentially expose the Company to credit risk primarily consist of cash, cash equivalents, restricted cash and investments. The Company maintains its cash, cash equivalent, restricted cash and investment balances with accredited financial institutions and, consequently, the Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company’s cash management and investment policy limits investment instruments to investment-grade securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (FDIC) up to $ 250,000 . As of December 31, 2021 and 2020, the Company’s primary operating accounts significantly exceeded the FDIC limits. The Company is presently dependent on third-party manufacturers to supply materials for research and development activities of its programs, including clinical and preclinical testing. The Company’s development programs could be adversely affected by a significant interruption in the supply of the necessary materials. The Company is also dependent on third parties who provide license rights used in the development of certain programs. The Company could experience delays in the development of its programs if any of these license agreements are terminated, if the Company fails to meet the obligations required under its arrangements, or if the Company is unable to successfully secure new strategic alliances or licensing agreements. For the year ended December 31, 2021, Jazz accounted fo r 49 % of total collaboration revenue and Sarepta accounted for 51 % of total collaboration revenue. For the year ended December 31, 2020, Jazz accounted for 22 % of total collaboration revenue and Sarepta accounted for 78 % of tot al collaboration revenue. Off-balance sheet risk As of December 31, 2021 and 2020, the Company had no off-balance sheet risks such as foreign exchange contracts, option contracts or other foreign hedging arrangements. Fair value of financial instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures (ASC 820), establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: Level 1 — Valuations based on quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3 —Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Items measured at fair value on a recurring basis include cash equivalents as of December 31, 2021 and 2020 . Certain cash equivalents that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The carrying amounts reflected in the consolidated balance sheets for prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term maturities. Property and equipment Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated useful life Computer equipment and software 3 years Furniture and fixtures 5 years Laboratory and manufacturing equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Purchased assets that are not yet in service are recorded to construction-in-progress and no depreciation expense is recorded. Once they are placed in service they are reclassified to the appropriate asset class and depreciated over their respective estimated useful lives. Upon the retirement or sale of an asset, the related cost and accumulated depreciation or amortization is removed from the accounts and any resulting gain or loss is recorded to other income (expense), net. Expenditures for maintenance and repairs are expensed as incurred. Impairment of long-lived assets The Company periodically evaluates its long-lived assets, which consist of property and equipment, prepaid manufacturing services and right-of-use-assets, for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. If such events or changes in circumstances arise, the Company compares the carrying amount of the long-lived assets to the estimated future undiscounted cash flows expected to be generated by the long-lived assets. If the estimated aggregate undiscounted cash flows are less than the carrying amount of the long-lived assets, an impairment charge, calculated as the amount by which the carrying amount of the assets exceeds the fair value of the assets, is recorded. The fair value of the long-lived assets is determined based on the estimated discounted cash flows expected to be generated from the long-lived assets. The Company has no t recorded any such impairment charges during the years ended December 31, 2021 or 2020 . Term loan The Company accounts for its Loan and Security Agreement with Hercules as a liability measured at net proceeds less debt discount and is accreted to the associated face value of the term loan over its respective expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to FASB ASC Topic 815, Derivatives and Hedging . The Company capitalizes certain legal and other third-party fees that are directly associated with obtaining access to capital under credit facilities. Deferred financing costs related to a recognized debt liability are recorded as a reduction of the carrying amount of the debt liability and amortized to interest expense using the effective interest rate method. Deferred financing costs related to the term loan were less than $ 0.1 million for the years ended December 31, 2021 and 2020, respectively. Leases The Company accounts for leases in accordance with ASC 842, Leases . Leases are classified at their commencement date, which is defined as the date on which the lessor makes the underlying asset available for use by the lessee, as either operating or finance leases based on the economic substance of the agreement. Lease liabilities are measured at the lease commencement date as the present value of the future lease payments using the interest rate implicit in the lease. If the rate implicit is not readily determinable, the Company will utilize their incremental borrowing rate as of the lease commencement date. If the rate implicit is not readily determinable, the Company will utilize their incremental borrowing rate as of the lease commencement date. Lease right-of-use assets are measured as the lease liability plus initial direct costs and prepaid lease payments less lease incentives. The lease term is the non-cancelable period of the lease, adjusted for any options to extend or terminate when it is reasonably certain the Company will exercise such options. The Company does not recognize leases with an initial term of 12 months or less. The Company’s operating leases are presented in the consolidated balance sheets as operating lease right-of-use assets, classified as noncurrent assets, and operating lease liabilities, classified as current and noncurrent liabilities based on the portion of the lease liability that will mature within the proceeding twelve months. Operating lease expense for the minimum lease payments is recognized on a straight-line basis over the lease term. The Company assesses its right-of-use assets for impairment consistent with the assessment performed for long-lived assets used in operations. The Company evaluates its subleases in which it is the sublessor to determine whether it is relieved of the primary obligation under the original lease. If it remains the primary obligor, the Company continues to account for the original lease as it did before the commencement of the sublease and reports the sublease income on a gross basis in other income in the consolidated statements of operations and comprehensive loss. Redeemable convertible preferred stock Prior to the automatic conversion of all outstanding shares of the Company’s redeemable convertible preferred stock upon the closing of the IPO, the Company recorded all redeemable convertible preferred stock upon issuance at its respective fair value or original issuance price less issuance costs. The Company classified its redeemable convertible preferred stock outside of stockholders’ equity (deficit) as the redemption of such shares was outside the Company’s control. The Company adjusted the carrying values of the redeemable convertible preferred stock to redemption value when the redemption value exceeded the carrying value. As of December 31, 2021 and 2020, the Company did no t have any convertible preferred stock issued or outstanding. Revenue recognition The Company recognizes revenue in accordance with FASB ASC Topic 606, Revenue from Contracts with Customers (ASC 606). The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods and/or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identify the contract(s) with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) each performance obligation is satisfied. Pursuant to the guidance in ASC 606, the Company accounts for a contract with a customer that is within the scope of ASC 606 when all of the following criteria are met: (i) the arrangement has been approved by the parties and the parties are committed to perform their respective obligations, (ii) each party’s rights regarding the goods and/or services to be transferred can be identified, (iii) the payment terms for the goods and/or services to be transferred can be identified, (iv) the arrangement has commercial substance and (v) collection of substantially all of the consideration to which the Company will be entitled in exchange for the goods and/or services that will be transferred to the customer is probable. The Company assesses the goods and/or services promised within a contract which contains multiple promises to evaluate which promises are distinct. Promises are considered to be distinct and therefore, accounted for as separate performance obligations, provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) the promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. The Company determines that a customer can benefit from a good or service if it could be used, consumed, sold for an amount that is greater than scrap value, or otherwise held in a way that generates economic benefits. Factors that are considered in determining whether or not two or more promises are not separately identifiable include, but are not limited to, the following: (i) the Company provides a significant service of integrating goods and/or services with other goods and/or services promised in the contract, (ii) one or more of the goods and/or services significantly modifies or customizes, or are significantly modified or customized by, one or more of the other goods and/or services promised in the contract and (iii) the goods and/or services are highly interdependent or highly interrelated. Individual goods or services (or bundles of goods and/or services) that meet both criteria for being distinct are accounted for as separate performance obligations. Promises that are not distinct at contract inception are combined into a single performance obligation. Options to acquire additional goods and/or services are evaluated to determine if such option provides a material right to the customer that it would not have received without entering into the contract. If so, the option is accounted for as a separate performance obligation. If not, the option is considered a marketing offer which would be accounted for as a separate contract upon the customer’s election. The terms of the Company’s arrangements include the payment of one or more of the following: (i) non-refundable, up-front fees, (ii) cost reimbursements, (iii) development, regulatory and commercial milestone payments, (iv) royalties on net sales of licensed products and (v) profit share for co-commercialized products. The transaction price generally comprises of fixed fees due at contract inception and an estimate of variable consideration for cost reimbursements and milestone payments due upon the achievement of specified events. Additionally, the Company may earn sales milestones, tiered royalties earned when the licensee recognizes net sales of licensed products and potentially profit share related to co-commercialized products. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes either the expected value method or the most likely amount method to estimate the amount of variable consideration, depending on which method is expected to better predict the amount of consideration to which it will be entitled. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. With respect to development and regulatory milestone payments, at the inception of the arrangement, the Company evaluates whether the associated event is considered probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. As part of the evaluation for development milestone payments, the Company considers several factors, including the stage of development of the targets included in the arrangement, the risk associated with the remaining development work required to achieve the milestone and whether or not the achievement of the milestone is within the Company’s control. Milestone payments that are not within the control of the Company or the licensee, such as those dependent upon receipt of regulatory approval, are not considered to be probable of achievement until the triggering event occurs. With respect to sales-based royalties and profit share payments, including milestone payments based upon the achievement of a certain level of product sales, wherein the license is deemed to be the sole or predominant item to which the payments relate, the Company recognizes revenue upon the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any development, regulatory or commercial milestones, royalty or profit share revenue resulting from its arrangements with customers. The Company considered the existence of a significant financing component in its arrangements and has determined that a significant financing component does not exist due to the applicability of available practical expedients, existence of substantive business purposes and/or presence of other compelling factors. The Company updates its assessment of the estimated transaction price, including the constraint on variable consideration, at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur. Any adjustments to the transaction price are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. The Company generally allocates the transaction price to each performance obligation identified in the contract on a relative standalone selling price basis. However, certain components of variable consideration are allocated specifically to one or more particular performance obligations to the extent both of the following criteria are met: (i) the terms of the payment relate specifically to the efforts to satisfy the performance obligation or transfer the distinct good or service and (ii) allocating the variable amount of consideration entirely to the performance obligation or the distinct good or service is consistent with the allocation objective of the standard whereby the amount allocated depicts the amount of consideration to which the entity expects to be entitled in exchange for transferring the promised goods or services. The Company develops assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The key assumptions utilized in determining the standalone selling price for the performance obligations may include forecasted revenues, development timelines, estimated research and development costs, discount rates, other comparable transactions, likelihood of exercise and probabilities of technical and regulatory success. Revenue is recognized based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good and/or service to the customer. For performance obligations that are satisfied at a point in time, the Company recognizes revenue when control of the goods and/or services is transferred to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company generally uses input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. With respect to promises related to licenses to intellectual property that is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from amounts allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. The Company receives payments from its licensees in accordance with the terms of the contracts. Up-front payments and fees are recorded as contract liabilities upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as contract liabilities, net of current portion. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional. Research and development expense Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, contract services and other related costs. The value of goods and services received from contract research organizations and contract manufacturing organizations in the reporting period are estimated based on the level of services performed, and progress in the period in cases when the Company has not received an invoice from the supplier. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense. Patent costs Costs to secure, defend and maintain patents are expensed as incurred due to the uncertainty of future benefits and are classified as general and administrative expenses. Stock-based compensation The Company issues stock-based awards to employees and non-employees, generally in the form of stock options and restricted stock units (RSUs). The Company accounts for stock-based compensation awards in accordance with ASC 718, Compensation—Stock Compensation. Most of its stock-based awards have been made to employees. The Company measures compensation cost for equity awards at their grant-date fair value and recognize compensation expense over the requisite service period, which is generally the vesting period, on a straight-line basis. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model, which requires management to make assumptions with respect to the fair value of the common stock on the grant date, including the expected term of the award, the expected volatility of the stock, calculated based on a period of time generally commensurate with the expected term of the award, risk-free interest rates and expected dividend yields of the stock. Historically, for periods prior to the IPO, the fair value of the shares of common stock and common units underlying our stock-based awards were determined on each grant date by the board of directors based on valuation estimates from management considering our most recently available independent third-party valuation of the common stock. The board of directors also assessed and considered, with input from management, additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the grant date. The grant date fair value of RSUs is estimated based on the fair value of the underlying common stock. For performance-based stock awards, The Company recognizes stock-based compensation expense over the requisite service period using the accelerated attribution method when achievement is probable. The Company classifies stock-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified. The Company uses the simplified method prescribed by Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment , to calculate the expected term of options granted to employees, non-employees and directors. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future. Income taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be re

Derecognition of Business

Derecognition of Business	12 Months Ended
	Dec. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Derecognition of Business	3. Derecognition of Business Arrangement Summary On November 1, 2021, the Company entered into an Asset Purchase Agreement (the Asset Purchase Agreement) with Lonza Rockland, Inc. (Lonza). Under the terms of the Asset Purchase Agreement, Lonza acquired all of the assets, properties and rights related to the Company’s business of manufacturing exosomes for use in clinical and non-clinical studies and the associated laboratory facility, with the exception of any activities associated with exosome modification and formulation. The closing of the transactions contemplated by the Asset Purchase Agreement (the Lonza Closing) occurred on November 15, 2021. At the Lonza Closing, certain specialized manufacturing and quality personnel of the Company became employees of Lonza (the Transferred Employees). In connection with the Lonza Closing, the Company entered into a Manufacturing Services Agreement (the Manufacturing Services Agreement) with Lonza which became effective on November 15, 2021. Pursuant to the terms of the Manufacturing Services Agreement, Lonza became the exclusive manufacturing partner for the production of the Company’s exosome products, subject to limited exceptions. As consideration for the transactions contemplated by the Asset Purchase Agreement and the associated ancillary agreements, the Company is entitled to approximately $ 65.0 million worth of exosome manufacturing services for its clinical programs during the next four years . To the extent the Company elects to use any free and/or discounted manufacturing services available under the Manufacturing Services Agreement, it would be responsible for bearing any accompanying materials costs, external costs and a handling fee. Lonza is permitted to terminate the Manufacturing Services Agreement for any or no reason with 12 months advance notice provided at any time after November 15, 2023. Accordingly, the Company’s ability to utilize the free and discounted manufacturing services available under the Manufacturing Services Agreement in periods beyond November 15, 2024 is subject to Lonza’s right to terminate. The Manufacturing Services Agreement may also be terminated upon the occurrence of certain other events, including customary termination provisions. Concurrently with the Lonza Closing, the Company and Lonza executed a License and Collaboration Agreement (the License Agreement) on November 15, 2021. Pursuant to the terms of the License Agreement, the Company granted to Lonza an exclusive, worldwide, perpetual and sublicensable license to its high-throughput exosome manufacturing intellectual property in the contract development and manufacturing field. The Company is eligible to receive from Lonza a double-digit percentage of future sublicensing revenues per the terms of the License Agreement. No sublicensing revenue had been received by the Company or earned by Lonza through December 31, 2021. Also contemporaneous with the Lonza Closing, the Company and Lonza entered into a Sublease Agreement (the Sublease Agreement) pursuant to which Lonza subleased the premises at which the Company’s exosome manufacturing operations were located. The initial lease term commenced on November 15, 2021 and continues through November 30, 2024 . Under the terms of the Sublease Agreement, Lonza is obligated to pay the Company approximately $ 1.0 million of fixed rent charges per year, subject to a 2.8 % annual increase, plus certain operating expenses and other costs. The Company retained the primary obligation under the original lease upon execution of the Sublease Agreement. Upon termination of the Manufacturing Services Agreement on or prior to December 31, 2025, some aspects of the transactions contemplated by the Asset Purchase Agreement and related ancillary agreements are required to be reverted, including with respect to certain assets, properties and rights that were transferred to Lonza. Upon termination or expiration of the Sublease Agreement at any time after December 31, 2025, some aspects of the transactions contemplated by the Asset Purchase Agreement and related ancillary agreements are subject to potential reversion at Lonza’s option, including with respect to certain assets, properties and rights that were transferred to Lonza. Accounting Analysis The Company concluded that the Asset Purchase Agreement and pertinent elements of the Manufacturing Services Agreement, the License Agreement and the Sublease Agreement comprise a single transaction because they were entered into in contemplation of one another and designed to achieve an overall commercial effect. Together, the related transactions consummated amongst the multiple contracts culminate in the transfer of the Company’s exosome manufacturing operations to Lonza (the Lonza Transfer Transaction). The Company concluded that the Lonza Transfer Transaction represents the disposition of a business. This determination is based on the fact that the license in the contract development and manufacturing field conveyed under the License Agreement by Lonza and the Transferred Employees to manufacture drug product using the equipment transferred under the Asset Purchase Agreement. Accordingly, the Company applied the derecognition guidance in ASC 810-10-40 in accounting for the transaction since Lonza is not a customer for any aspect of the arrangement. The Company’s control over the exosome manufacturing business transferred to Lonza was lost upon the closing of the transactions contemplated by the Asset Purchase Agreement and related ancillary agreements on November 15, 2021. Therefore, the Company recognized a gain upon derecognition on November 15, 2021. The gain was calculated as the difference between: (i) the fair value of the non-cash consideration and (ii) the carrying amount of the underlying group of assets. Because Lonza is entitled to terminate the Manufacturing Services Agreement for any or no reason with 12 months ’ notice after November 15, 2023, the Company determined that any non-cash consideration scheduled beyond November 15, 2024 is contingent consideration since its ability to utilize the associated free and discounted manufacturing services is subject to Lonza’s right to terminate. The Company also treated the sublicensing revenue that may become payable under the License Agreement as contingent consideration since the receipt of any such amounts is dependent on Lonza engaging in sublicensing transactions, which is not expected to be material. Neither of the elements of contingent consideration is required to be accounted for as a derivative instrument because either the payments do not meet the definition of a derivative or qualify for a scope exception from derivative accounting. Consequently, the consideration attributable to the Lonza Transfer Transaction is limited to the non-cash consideration due to the Company under the Manufacturing Services Agreement and the sublicensing fees to which the Company is entitled under the License Agreement. The Company recorded the aggregate consideration, including the contingent consideration, at its fair value as of November 15, 2021. The aggregate fair value of the non-cash consideration represents the total discounted cash flows associated with the manufacturing expenditures expected to be avoided over the period the free and discounted services are available. The value of the costs that would otherwise be incurred was determined in reference to comparable costs charged by unrelated third-parties. The Company also incorporated a breakage factor in deriving the estimated fair value of the non-cash consideration to reflect expectations around utilization by the Company and termination by Lonza. The Company classified the Manufacturing Services Agreement as a Level 3 fair value measurement for the periods presented. The discounted cash flow approach relies primarily on Level 3 unobservable inputs, whereby expected future cash flows are discounted using a rate that includes assumptions regarding an entity’s average cost of debt and equity, incorporates expected future cash flows based on internal business plans, and applies certain assumptions about risk and uncertainties. As of November 15, 2021, the Company estimated the aggregate fair value of such non-cash consideration, including the associated contingent consideration, to be approximately $ 39.2 million. The Company does not expect to earn any significant sublicensing fees or other consideration from the transaction. Amounts payable under the Sublease Agreement based on the contractually stated rates approximate the fair value of the associated rights conveyed as of November 15, 2021. Therefore, the Company has accounted for the Sublease Agreement separately from the disposition of the business. No amount has been allocated from the other consideration in the arrangement to this element. The Company removed the carrying amounts associated with the net assets that transferred to Lonza in connection with the transaction from its accounts as of November 15, 2021. Such assets primarily comprises certain laboratory equipment that was located at the facility on November 15, 2021. Below is the calculation of the gain recognized upon derecognition of the group of assets that transferred to Lonza on November 15, 2021: Element Amount Fair value of consideration $ 39,170 Carrying amount of assets transferred ( 4,823 ) Transaction costs ( 526 ) Share-based payment modification expense ( 535 ) Gain on derecognition $ 33,286 The gain includes the non-cash consideration of the prepaid manufacturing costs, less any assets transferred, legal fees for services rendered by third parties associated with the transaction, “Transaction costs”, and equity modification costs that are direct costs associated with the transfer of the business (Note 14). The gain recognized upon derecognition of the group of assets is presented as gain on disposition and is a component of non-operating income (loss) in the accompanying consolidated statement of operations and comprehensive loss for the year-ended December 31, 2021. The Company has recorded the aggregate fair value of the non-cash consideration as a prepaid manufacturing cost asset as of November 15, 2021. The Company will amortize the prepaid manufacturing services asset as requested services are rendered by Lonza under the Manufacturing Services Agreement, subject to impairment assessments. Such amount is classified as current or noncurrent based on the timing of when the associated services are expected to be utilized by the Company. Amounts expected to be consumed within the 12 months following December 31, 2021 are classified within current assets as prepaid manufacturing services in the accompanying consolidated balance sheet as of December 31, 2021, while the remainder is classified as a noncurrent asset in the accompanying consolidated balance sheet as of December 31, 2021.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	. Fair value measurements The following tables present information about the Company’s assets measured at fair value on a recurring basis, and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands): DECEMBER 31, 2021 TOTAL LEVEL 1 LEVEL 2 LEVEL 3 NOT Assets: Cash equivalents: Money market funds $ 67,603 $ — $ — $ — $ 67,603 $ 67,603 $ — $ — $ — $ 67,603 DECEMBER 31, 2020 TOTAL LEVEL 1 LEVEL 2 LEVEL 3 NOT Assets: Cash equivalents: Money market funds $ 81,601 $ — $ — $ — $ 81,601 $ 81,601 $ — $ — $ — $ 81,601 (1) Certain cash equivalents that are valued using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. As of December 31, 2021 and 2020, the Company’s cash equivalents consisted of money market funds invested in US Treasury securities with original maturities of less than 90 days from the date of purchase. During the years ended December 31, 2021 and 202 0 , there were no transfers between Level 1, Level 2 and Level 3. The fair value of the Company’s debt is classified as Level 2 for the periods presented and approximates its carrying value due to the variable interest rate.

Investments

Investments	12 Months Ended
	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Investments	5. Investments All of the Company’s investments matured during the year ended December 31, 2020 . The Company did no t hold any investments as of December 31, 2021 . The Company recognized less than $ 0.1 million of realized gains in the year ended December 31, 2020 and did no t recognize any realized gains or losses for the year ended December 31, 2021 .

Prepaids and Other Current Asse

Prepaids and Other Current Assets	12 Months Ended
	Dec. 31, 2021
Prepaid Expense and Other Assets, Current [Abstract]
Prepaids and Other Current Assets	. Prepaids and other current assets Prepaid expenses and other current assets consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Clinical trial costs $ 1,053 $ 805 Prepaid insurance 2,593 2,598 Other receivables 1,289 31 Other prepaid expenses and other current assets 983 1,308 $ 5,918 $ 4,742

Property and Equipment, Net

Property and Equipment, Net	12 Months Ended
	Dec. 31, 2021
Property Plant And Equipment [Abstract]
Property and Equipment, Net	. Property and equipment, net Property and equipment, net, consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Leasehold improvements $ 21,691 $ 23,949 Laboratory equipment 11,898 14,837 Furniture and fixtures 1,208 1,288 Computer equipment and software 119 159 Construction-in-process 372 1,667 $ 35,288 $ 41,900 Less: Accumulated depreciation and amortization ( 11,809 ) ( 10,490 ) Property and equipment, net $ 23,479 $ 31,410 Depreciation and amortization expense related to property and equipment for the years ended December 31, 2021 and 2020 was $ 5.5 million and $ 4.4 million, respectively. During the year ended December 31, 2021 the Company sold laboratory equipment with a net book value of $ 4.8 million, which is recognized as a component of the gain on disposition (Note 3). In addition, during the year ended December 31, 2021, the Company wrote off leasehold improvements, during the normal course of business, with a net book value of less than $ 0.1 million, and is recognized as a component of other income (expense).

Restricted Cash

Restricted Cash	12 Months Ended
	Dec. 31, 2021
Cash and Cash Equivalents [Abstract]
Restricted Cash	. Restricted cash As of December 31, 2021 , the Company had restricted cash of $ 4.2 million held as letters of credit issued by an FDIC-insured financial institution as security deposits, as required under the Company’s 4 Hartwell Place and 35 CambridgePark Drive lease agreements. As of December 31, 2021 , and 2020, all restricted cash was classified as a non-current asset because the associated lease terms expired more than 12 months from the respective consolidated balance sheet date, respectively.

Accrued Expenses

Accrued Expenses	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Accrued Expenses	9. Accrued expenses Accrued expenses consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Accrued employee compensation $ 5,142 $ 5,040 Accrued external research and development costs 2,420 1,475 Accrued professional services and consulting 1,523 902 Accrued facilities costs 190 846 Other expenditures 428 607 $ 9,703 $ 8,870

Leases

Leases	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	. Leases The Company has entered into various long-term non-cancelable lease arrangements for its facilities, expiring at various times through 2029 . Certain arrangements have free rent periods or escalating rent payment provisions; costs under such arrangements are recognized on a straight-line basis over the life of the leases. The Company has two locations in Massachusetts, its office and laboratory, located in Cambridge and manufacturing space, located in Lexington, which is currently being leased and operated by Lonza (Note 3). Operating Leases 500 Technology Square The Company leased building space at 500 Technology Square in Cambridge, Massachusetts. Under the terms of the lease, the Company leased approximately 19,823 square feet for $ 1.5 million per year in base rent, which was subject to a 2.5 % annual rent increase plus certain operating expenses and taxes. The Company accounted for this lease as an operating lease. The lease commenced on December 28, 2016 and originally expired on December 31, 2021 . On August 26, 2019, the Company signed a lease termination to accelerate the expiration date of the lease to February 28, 2020 . 4 Hartwell Place On March 5, 2019, the Company entered into a lease for manufacturing space at 4 Hartwell Place, ("4 Hartwell") in Lexington, Massachusetts. Under the terms of the lease, the Company leases approximately 18,707 square feet for $ 0.9 million per year in base rent, which is subject to a 2.6 % annual rent increase during the initial lease term, plus certain operating expenses and taxes. The lease term commenced in July 2019 and will end in December 2029 . The Company has the option to extend the lease twice, each for a five-year period, on the same terms and conditions as the current lease, subject to a change in base rent based on market rates. The Company had fully occupied the space as of December 31, 2020. Upon execution of the lease agreement, the Company provided a security deposit of $ 0.4 million which is held in the form of a letter of credit and was classified as non-current restricted cash on the condensed consolidated balance sheets as of December 31, 2021 and December 31, 2020 . The lease provided the Company with a tenant improvement allowance of up to $ 1.3 million, which is being amortized as a reduction to rent expense over the remaining lease term. As of December 31, 2021, the Company had received al l $ 1.3 million o f the tenant improvement allowance. Costs incurred related to the allowance are capitalized as leasehold improvements. On November 15, 2021, the Company entered into an amendment to the lease (the Master Lease Amendment) for the property located at 4 Hartwell Place in Lexington, Massachusetts. The only change to the terms of the lease was to increase the base rent by $ 0.1 million per year. There were no initial direct costs incurred, incremental incentives received or any other payments made to or by the Company with respect to the Master Lease Amendment. The Company accounted for the changes made to the lease agreement as a lease modification. The Company determined that the associated lease should continue to be accounted for as an operating lease with a lease term commensurate with the initial lease term which ends in December 2029. The Company remeasured the lease liability as of November 15, 2021 based on the then-current applicable incremental borrowing rate resulting in an increase of $ 1.0 million which was offset by an equal adjustment made to the corresponding right-of-use asset. 35 CambridgePark Drive On March 22, 2019, the Company entered into a non-cancelable property lease for office and laboratory space at 35 CambridgePark Drive, ("35 CambridgePark") in Cambridge, Massachusetts. Under the terms of the lease, the Company leases approximately 68,258 square feet for $ 4.9 million per year in base rent, which is subject to a 3.0 % annual rent increase during the initial lease term, plus certain operating expenses and taxes. The Company accounts for this lease as an operating lease. The lease term commenced upon execution of the lease on March 26, 2019 and is expected to end in November 2029 . The Company has the option to extend the lease for a 10-year period on the same terms and conditions as the current lease, subject to a change in base rent based on market rates. The Company occupied the space in February 2020 as its new corporate headquarters. Upon execution of the lease agreement, the Company provided a security deposit of $ 3.7 million which is held in the form of a letter of credit and is classified as non-current restricted cash on the accompanying consolidated balance sheets as of December 3, 2020 and 2019. The lease provides the Company with a tenant improvement allowance of $ 12.3 million, subject to reduction for a 2 % construction oversight fee due to the landlord, which is being amortized as a reduction to rent expense over the remaining lease term. As of December 31, 2020, the Company had received all $ 12.3 million of the tenant improvement allowance. Costs incurred related to the allowance are capitalized as leasehold improvements. Subleases 4 Hartwell Place On November 15, 2021, the Company entered into a sublease agreement with Lonza for the entirety of its leased space at 4 Hartwell Place in Lexington, Massachusetts, as discussed in Note 3. Under the terms of the Sublease Agreement, Lonza is obligated to pay the Company base rent of approximately $ 1.0 million per year, subject to a 2.8 % annual increase, plus certain operating expenses and other costs. The initial lease term commenced on November 15, 2021 and continues through November 30, 2024 . Lonza has the option to extend the sublease term for five 12-month periods on the same terms and conditions as the current sublease, subject to an increase of 2.8 % in the annual fixed rent charges. Additionally, Lonza has the right to have the associated master lease assigned to it beginning on January 1, 2026, subject to the landlord’s consent. As of December 31, 2021, the Company has not been legally released from its primary obligations under the original lease. Therefore, the Company continues to account for the original lease as it did before commencement of the sublease, inclusive of the effects of the Master Lease Amendment. The Company determined that the sublease term is commensurate with the initial sublease term because it is not reasonably certain that any of the extension options will be exercised. 35 CambridgePark Drive On April 27, 2020, the Company entered into a sublease for 23,280 square feet of its leased space at 35 CambridgePark Drive. Under the terms of the sublease, the sublessee was to pay the Company approximately $ 1.3 million per year, which was subject to a 3.0 % annual rent increase, plus certain operating expenses. The lease term commenced on May 18, 2020 and was expected to end in May 2022 . The sublessee had the option to extend the sublease for a one-year period on the same terms and conditions as the current sublease, subject to a change in base rent based on the greater of (i) an increase of 3% of the annual rent owed by the sublessee in year two, and (ii) market rent for the subleased premises. Upon execution of the sublease agreement, the sublessee provided the Company a security deposit of $ 0.3 million which is held in the form of a letter of credit. Effective July 1, 2021, the Company received notice of the sublessee’s intent to exercise its option to extend the sublease for a one-year period through May 2023 . The Company increased the base rent of the option period to reflect a market-based fixed annual rate beginning June 2022. The Company remains jointly and severally liable under the head lease and accounts for the sublease as an operating lease. The lease term is now expected to end in May 2023 . During the year ended December 31, 2021 and 2020, the Company recognized sublease income o f $ 1.8 million and $ 0.9 million, which is presented in other income in the accompanying consolidated statement of operations and comprehensive loss, respectively. The components of operating lease costs were as follows (in thousands): FOR THE YEAR ENDED DECEMBER 31, 2021 2020 Operating lease costs $ 4,882 $ 4,836 Short-term lease costs 27 19 Variable lease costs 2,582 2,222 Sublease income ( 1,850 ) ( 861 ) $ 5,641 $ 6,216 Variable lease costs were primarily related to operating expenses, taxes and utilities associated with the operating leases, which were assessed based on the Company’s proportionate share of such costs for the leased premises. Additional lease information is summarized in the following table (in millions, except lease term and discount rate): FOR THE YEAR ENDED DECEMBER 31, 2021 2020 Cash paid for amounts included in the measurement of operating $ 6.0 $ 6.0 Weighted-average remaining lease term - operating leases (years) 7.9 8.9 Weighted-average discount rate - operating leases 10.1 % 10.3 % Undiscounted cash flows used in calculating the Company’s operating lease liabilities and amounts to be received under the sublease at 35 CambridgePark Drive and 4 Hartwell Place as of December 31, 2021 are as follows (in thousands): Fiscal Year OPERATING SUBLEASE NET 2022 $ 6,252 $ 2,821 $ 3,431 2023 6,436 1,962 4,474 2024 6,625 936 5,689 2025 6,820 6,820 2026 7,020 7,020 Thereafter 21,779 21,779 Total undiscounted cash flows $ 54,932 $ 5,719 $ 49,213 Less: Amounts representing interest ( 17,387 ) Present value of lease liabilities $ 37,545

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	11. Commitments and contingencies Manufacturing Services Agreement As discussed in Note 3, the Company and Lonza entered into a Manufacturing Services Agreement which became effective on November 15, 2021. The Manufacturing Services Agreement outlines the terms and conditions under which Lonza will develop, manufacture and supply exosome products for development and clinical purposes. The parties will negotiate and execute an amendment to the Manufacturing Services Agreement to address the commercial manufacture of the Company’s exosome products. Each individual project to be completed under the Manufacturing Services Agreement is governed by an associated statement of work which sets forth the activities to be performed, timeline, charges and payment schedule applicable to such project. Pricing is established on a project-by-project basis. Statements of work are executed between the parties on an as-requested basis. No activities had commenced with respect to outstanding statements of work through December 31, 2021. The Company is subject to certain cancellation fees and/or other charges upon its termination of statements of work and in the event of a suspension or delay in the conduct of statements of work, including with respect to the reimbursement of non-cancelable costs incurred by Lonza. Through December 31, 2021, the Company has no t incurred any cancellation fees or other charges relating to a termination, suspension or delay of outstanding statements of work. Under the terms of the Manufacturing Services Agreement, the Company is obligated to purchase the entirety of its aggregate production needs from Lonza, subject to limited exceptions. Starting on June 1, 2022, the Company will provide to Lonza rolling forecasts of its anticipated manufacturing time requirements for the next 24 months from the date of the forecast which will be updated no less frequently than quarterly. The first 12 months of each forecast will be a binding commitment, while the remaining 12 months will be non-binding. Commencing on January 1, 2026, the Company is bound by a commitment to purchase from Lonza a minimum of a specified number of weeks of manufacturing time each year at a predetermined price throughout the term of the arrangement. The Company’s minimum purchase commitments under the Manufacturing Services Agreement may be relieved at its option upon the occurrence and during the pendency of certain liquidation events or clinical discontinuations. As of December 31, 2021, the Company did no t have any minimum non-cancelable purchase obligations under the Manufacturing Services Agreement. Pursuant to the terms of the Manufacturing Services Agreement, the Company is entitled to a specified number of weeks of manufacturing time and a defined number of technology transfers from Lonza at no cost, with the exception of any accompanying materials costs, external costs and a handling fee. Additionally, the terms of the Manufacturing Services Agreement provide the Company with a specified number of weeks of manufacturing time from Lonza at a discounted rate, subject to annual adjustment. The Company bears the expense associated with any materials costs, external costs and a handling fee related to the discounted manufacturing time. Manufacturing services in excess of the free and discounted time are priced at a fixed weekly rate, plus materials costs, external costs and a handling fee. The Company’s consumption of the free and discounted manufacturing time, including the associated technology transfer services, is subject to a contractually-specified apportionment by year commencing in 2022 and continuing through 2025. The Company’s failure to use the free and discounted manufacturing time within the assigned period results in its forfeiture unless such inability is not due to the Company or Lonza permits carryover to a subsequent period. Unless earlier terminated or extended by the parties, the Manufacturing Services Agreement remains in effect until the earlier of: (i) Fifth anniversary of the first approval of a biologics license application by the U.S. Food and Drug Administration for any of the Company’s exosome products or (ii) Tenth anniversary of Lonza’s completion of the services associated with the free manufacturing time. The Manufacturing Services Agreement is subject to customary termination provisions. Additionally, Lonza may terminate the Manufacturing Services Agreement with 12 months advance notice for any or no reason at any time after November 15, 2023. To the extent the Manufacturing Services Agreement is terminated on or prior to December 31, 2025, certain aspects of the transactions consummated in connection with the Lonza Transfer Transaction will be reverted, including with respect to assets, properties and rights that transferred to Lonza effective on November 15, 2021. Lonza has the right to cease manufacturing under the Manufacturing Services Agreement upon either: (i) The Company unreasonably withholding, conditioning or delaying its approval of certain price changes or (ii) The Company enduring certain liquidation events or clinical discontinuations. Any termination of the Manufacturing Services Agreement for any reason will be without prejudice to any rights that will have accrued to the benefit of a party prior to such termination. Under the Company’s Sponsored Research Agreement with the University of Texas MD Anderson Cancer Center (MDACC), as amended (the MDACC Research Agreement), the Company was obligated to pay fixed quarterly cash payments to MDACC over the term of the agreement. The Company was also obligated to make additional quarterly payments pursuant to the MDACC Research Agreement, payable in the form of a fixed number of the Company’s Series B redeemable convertible preferred stock throughout the remainder of the agreement. Pursuant to the Third Amendment to the MDACC Research Agreement, the termination date was modified to be effective December 31, 2019. The Company made the final $ 1.2 million cash payment and issued the remaining shares of Series B redeemable convertible preferred stock to MDACC in January 2020. There are no further payments or share issuances owed to MDACC pursuant to the MDACC Research Agreement. The Company also has a license agreement with MDACC under which the Company is obligated to pay milestone payments upon the achievement of development and regulatory milestones and payments upon the execution of sublicenses for qualifying products, in addition to potential royalty payments on commercial products. Additionally, the Company has a license agreement with Kayla Therapeutics S.A.S. (Kayla) under which the Company is obligated to make milestone payments upon the achievement of clinical and regulatory milestones and payments upon the execution of sublicenses, in addition to potential royalty payments on commercial products. The first milestone was achieved upon the dosing of the first subject in the Company’s exoSTING Phase 1/2 clinical trial in September 2020. Upon achievement of the milestone, the Company was obligated to make a nonrefundable payment of $ 15.0 million in cash and issue 177,318 shares of common stock to Kayla. The common stock was issued as of the date of dosing, and the cash payment of $ 15.0 million was paid during 2020. The expense related to the milestone payment to Kayla was recorded as research and development expense in the year ended December 31, 2020 because the associated asset was in development at the time the contingency that triggered the milestone was resolved . Purchase orders The Company has agreements with third parties for various services, including services related to clinical and preclinical operations and support, for which the Company is not contractually able to terminate for convenience to avoid future obligations to the vendors. Certain agreements provide for termination rights subject to termination fees or wind down costs. Under such agreements, the Company is contractually obligated to make certain payments to vendors, primarily to reimburse them for their unrecoverable outlays incurred prior to cancelation. The actual amounts the Company could pay in the future to the vendors under such agreements may differ from the purchase order amounts due to cancellation provisions. Indemnification agreements The Company enters into standard indemnification agreements and/or indemnification sections in other agreements in the ordinary course of business. Pursuant to the agreements, the Company indemnifies, holds harmless, and agrees to reimburse the indemnified party for losses suffered or incurred by the indemnified party, generally the Company’s business partners. The term of these indemnification agreements is generally perpetual any time after execution of the agreement. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is unlimited. The Company has never incurred costs to defend lawsuits or settle claims related to these indemnification agreements. The Company does not believe that the outcome of any existing claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it had not accrued any liabilities related to such obligations in its condensed consolidated balance sheets as of December 31, 2021 or December 31, 2020. Legal proceedings The Company is not currently party to any material legal proceedings. At each reporting date, the Company evaluates whether or not a potential loss amount or a potential range of loss is probable and reasonably estimable under the provisions of FASB ASC Topic 450, Contingencies . The Company expenses as incurred the costs related to its legal proceedings.

Indebtedness

Indebtedness	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Indebtedness	12. Indebtedness On September 30, 2019 (the Hercules Closing Date), the Company entered into a Loan and Security Agreement (the Loan Agreement) with Hercules pursuant to which a term loan in an aggregate principal amount of up to $ 75.0 million (the Term Loan Facility) was available to the Company in four tranches, subject to certain terms and conditions. Ten million of the first tranche was advanced to the Company on the Hercules Closing Date, and an additional $ 15.0 million under the first tranche was drawn down on July 24, 2020. Under the Loan Agreement, there were three additional tranches available to the Company of $ 10.0 million (tranche two), $ 10.0 million (tranche three), and $ 30.0 million (tranche four). As of December 31, 2021 , tranche two and three had expired. The total principal available under the Term Loan Facility as of December 31, 2021 was $8 5.0 million. Upon issuance, the initial advance under the first tranche was recorded as a liability with an initial carrying value of $ 9.5 million, net of debt issuance costs. The July 24, 2020, advance under the first tranche was recorded as a liability with an initial carrying value of $ 15.0 million. The initial carrying value of all outstanding advances is accreted to the repayment amount, which includes the outstanding principal plus the end of term charge, through interest expense using the effective interest rate method over the term of the loan. Effective September 17, 2021, or the Second Hercules Closing Date, the Company amended the Loan Agreement with Hercules (the Amended Loan Agreement), increasing aggregate principal amount available from $ 75.0 million under the Term Loan Facility to $ 85.0 million (the Amended Term Loan Facility). Under the Amended Term Loan Facility, a new tranche three of $ 10.0 million was established and is available immediately at the Company’s option through December 15, 2021. As of December 31, 2021 this tranche has expired. Tranche four was amended such that the $ 30.0 million available is now available through the interest only period, subject to future lender investment committee approval. Tranche five of up to $ 20.0 million was established under the Amended Loan Agreement and is available through September 30, 2023, upon satisfaction of certain clinical milestones. Tranche five is only available in minimum draws of $ 5.0 million. Advances under the Amended Term Loan Facility bear interest at a rate equal to the greater of (i) 8.25 % plus the Prime Rate (as reported in The Wall Street Journal) less 3.25 %, and (ii) 8.25 %. The interest only period under the Term Loan Facility was extended from November 1, 2022 to October 1, 2023 under the Amended Term Loan Facility and is further extendable to October 1, 2024 upon achievement of certain clinical milestones. Under the Amended Term Loan Facility, following the interest only period, the Company will repay the principal balance and interest on the advances in equal monthly installments through October 1, 2025 , compared to October 1, 2024 under the Term Loan Facility. The Company may prepay advances under the Amended Loan Agreement, in whole or in part, at any time subject to a prepayment charge (Prepayment Premium) equal to: (i) 2.0 % of amounts so prepaid, if such prepayment occurs during the first year following the Second Hercules Closing Date, (ii) 1.5 % of the amount so prepaid, if such prepayment occurs during the second year following the Second Hercules Closing Date, or (iii) 1.0 % of the amount so prepaid, if such prepayment occurs after the second year following the Second Hercules Closing Date. Upon prepayment or repayment of all or any of the term loans under the Term Loan Facility, the Company will pay (in addition to any Prepayment Premium) an end of term charge of 5.5 % of the aggregate funded amount under the Term Loan Facility. With respect to the first tranche, an end of term charge of $ 1.4 million will be payable upon any prepayment or repayment. The end of term charge of $1.4 million, or 5.5% of the $ 25.0 million of principal advanced under the Term Loan Facility, remains payable at the maturity date under the original term Loan Facility of October 1, 2024 . To the extent that the Company is provided with additional advances under the Amended Term Loan Facility, the 5.5 % end of term charge will be applied to any such additional amounts, payable on October 1, 2025 , the amended maturity date of the Amended Term Loan Facility. The Company evaluated the Amended Loan Agreement and Amended Term Loan Facility with Hercules, in accordance with the provisions of ASC 470. The Company concluded that terms under the Amended Loan Agreement were not substantially different from those under the original Loan Agreement and the Amended Loan Agreement should be accounted for prospectively. The Amended Term Loan Facility remains secured by a lien on substantially all of the Company’s assets, other than the Company’s intellectual property. The Company has agreed not to pledge or grant a security interest on the Company’s intellectual property to any third party. The Amended Term Loan Facility also contains customary covenants and representations, including a liquidity covenant, whereby the Company is obligated to maintain, in an account covered by Hercules’ account control agreement, an amount equal to the lesser of: (i) 110 % of the amount of the Company’s obligations under the Amended Term Loan Facility, or (ii) the Company’s then-existing cash and cash equivalents, financial reporting covenant and limitations on dividends, indebtedness, collateral, investments, distributions, transfers, mergers or acquisitions, taxes, corporate changes, deposit accounts, and subsidiaries. The events of default under the Amended Loan Agreement include, without limitation, and subject to customary grace periods, the following: (i) any failure by the Company to make any payments of principal or interest under the Amended Loan Agreement, (ii) any breach or default in the performance of any covenant under the Amended Loan Agreement, (iii) the occurrence of a material adverse effect, (iv) any making of false or misleading representations or warranties in any material respect, (v) the Company’s insolvency or bankruptcy, (vi) certain attachments or judgments on the assets of the Company, or (vii) the occurrence of any material default under certain agreements or obligations of the Company’s involving indebtedness. If an event of default occurs, Hercules is entitled to take enforcement action, including acceleration of amounts due under the Amended Loan Agreement. As of December 31, 2021 and December 31, 2020 , the carrying value of the term loan was $ 25.4 million and $ 25.0 million, respectively, which is classified as a long-term liability on the Company’s condensed consolidated balance sheets as of each respective period. The fair value of debt is classified as Level 2 for the periods presented and approximates its carrying value. The future principal payments under the Loan Agreement are as follows as of December 31, 2021 (in thousands): Fiscal Year PRINCIPAL 2022 $ - 2023 2,773 2024 11,680 2025 10,547 $ 25,000 During the years ended December 31, 2021 and 2020 , the Company recognized $ 2.7 million and $ 1.9 million of interest expense related to the Loan Agreement, respectively, which is reflected as interest expense on the accompanying consolidated statements of operations and comprehensive loss.

Common Stock

Common Stock	12 Months Ended
	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Common Stock	13. Common Stock As of December 31, 2021, the Company’s Fourth Amended and Restated Certificate of Incorporation (the Fourth Certificate of Incorporation), authorized the Company to issue 150,000,000 shares of $ 0.0001 par value common stock. The shares of the Company’s common stock, subject to outstanding awards under the 2015 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, will be added back to the shares of common stock available for issuance under the 2020 Plan. As of December 31, 2021, there were 1,573,353 s hares available for future issuance under the 2020 Plan. DECEMBER 31, DECEMBER 31, Common stock reserved for exercises of outstanding stock options issued 4,763,489 4,543,318 Common stock reserved for future issuances 1,573,353 1,288,891 6,336,842 5,832,209

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2021
Employee Service Share Based Compensation Aggregate Disclosures [Abstract]
Stock-Based Compensation	14. Stock-based compensation Stock plans As of December 31, 2021 , the Company has granted service-based awards, which vest over a defined period of service, and performance-based and market-based awards, which vest upon the achievement of defined conditions. Service-based awards generally vest over a four-year period, with the first 25 % vesting following twelve months of continued employment or service, and the remainder vesting in twelve quarterly installments over the following three years . 2020 Stock Option and Incentive Plan The 2020 Stock Option and Incentive Plan (the 2020 Plan), was adopted by the Company’s board of directors in October 2020, approved by the Company’s stockholders in October 2020 and became effective as of October 12, 2020. The 2020 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, and other stock-based awards. The number of shares of the Company’s common stock initially reserved for issuance under the 2020 Plan was 1,043,402 shares. The number of shares reserved shall be annually increased on the first day of each calendar year beginning on January 1, 2021 and ending on and including January 1, 2030, equal to the lesser of 5 % of the number of shares of common stock outstanding on the final day of the immediately preceding calendar year or such lesser number of shares determined by the compensation committee. As of January 1, 2022, 1,119,192 additional shares of common stock were reserved for issuance under the 2020 Plan. The shares of the Company’s common stock, subject to outstanding awards under the 2015 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right, will be added back to the shares of common stock available for issuance under the 2020 Plan. The Company’s stock options expire after approximately ten years from the date of grant. As of December 31, 2021 , the Company does no t hold any treasury shares. Upon stock option exercise, the Company issues new shares and delivers them to the participant. 2020 Employee stock purchase plan The Company’s 2020 Employee Stock Purchase Plan, (the ESPP) was adopted by our board of directors in October 2020, approved by the Company’s stockholders in October 2020 and became effective October 12, 2020. The ESPP initially provides participating employees with the opportunity to purchase up to an aggregate of 208,680 shares of the Company’s common stock. The number of shares of common stock reserved for issuance under the ESPP will automatically increase on each January 1st, beginning on January 1, 2021 and ending on January 1, 2030, by the lesser of (i) 834,720 shares of common stock, (ii) 0.5 % of the outstanding shares of common stock on the immediately preceding December 31st or (iii) such lesser number of shares as determined by the administrator of the ESPP. Stock options The following table summarizes the Company’s stock option activity during the twelve months ended December 31, 2021: NUMBER WEIGHTED WEIGHTED AGGREGATE (In years) (In thousands) Outstanding as of December 31, 2020 4,543,318 $ 8.52 7.22 $ 108,048 Granted 1,449,400 23.26 Exercised ( 433,751 ) 8.62 Forfeited/Cancelled ( 795,478 ) 11.10 Outstanding as of December 31, 2021 4,763,489 12.56 6.44 10,370 Exercisable as of December 31, 2021 2,688,532 8.02 5.41 9,372 Vested and expected to vest as of December 31, 2021 4,763,489 12.56 6.44 10,370 (1) Aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock as of December 31, 2021 and 2020 . The weighted average grant date fair value per share of options granted during the years ended December 31, 2021 and 2020 was $ 14.33 and $ 8.30 , respectively. The aggregate intrinsic value of stock options exercised during the year ended December 31, 2021 and 2020 was $ 5.2 million and $ 0.4 million, respectively. Stock option valuation Service-based awards The key assumptions used in the Black-Scholes option pricing model on the date of grant for options with service-based vesting conditions granted to employees, directors and non-employees, were as follows, presented on a weighted average basis: YEAR ENDED 2021 2020 Risk-free interest rate 0.83 % 0.68 % Expected term (in years) 6.20 6.18 Expected volatility 68.21 % 68.75 % Expected dividend yield 0.00 % 0.00 % Fair value per share of common stock $ 14.37 $ 13.52 Performance-based awards The Company did no t grant any performance-based awards during the years ended December 31, 2021 or December 31, 2020. Stock-based compensation expense The following table presents the components and classification of stock-based compensation expense (in thousands): YEAR ENDED 2021 2020 Research and development $ 4,733 $ 3,563 General and administrative 5,409 3,517 Gain on disposition 535 - $ 10,677 $ 7,080 Employee $ 9,862 $ 6,547 Non-employee 815 533 $ 10,677 $ 7,080 The Company recognized stock-based compensation of $ 0.5 million, related to the Lonza transaction (Note 3) as a component of gain on disposition, which is recorded in other income (expense). The Company recognized expense of $ 0.3 million during the year ended December 31, 2020, related to performance-based awards that vested upon achievement of their underlying performance condition. As of December 31, 2021, all stock-based compensation expense related to previously granted performance-based awards has been recognized. As of December 31, 2021, the total unrecognized compensation expense related to the Company’s option awards was $ 20.3 million, which the Company expects to recognize over a weighted-average period of approximately 2.69 years Modifications On November 12, 2021, the Company amended certain terms applicable to outstanding option awards previously issued to the Transferred Employees in connection with the disposition transaction with Lonza. The Company modified the option awards previously granted to the Transferred Employees that were unvested as of November 12, 2021 to allow the individuals to continue to vest in outstanding awards subsequent to their termination of service. Additionally, the Company extended the post-termination exercise period for vested option awards previously granted to the Transferred Employees. The modifications affected awards previously granted to 12 individuals. None of the Transferred Employees have any continuing contractual relationship deemed to be substantial with the Company beyond November 12, 2021. The modifications were made in consideration of the termination of the Transferred Employees from the Company and the employment of the Transferred Employees by Lonza. The Company accounted for the changes made to the stock option awards held by Transferred Employees as modifications under ASC 718. The modification of the vesting condition associated with the unvested stock options was deemed a Type 3 modification because the options would have otherwise forfeited on the date of termination pursuant to the original terms of the awards. Accordingly, the Company measured compensation cost associated with these tranches based on the fair value of the modified awards as of November 12, 2021. The Company recognized stock-based compensation expense of approximately $ 0.4 million in connection with this modification. The Company recognized the impact in full on November 12, 2021 because the awards do not have an on-going service condition. The Company accounted for the modification to extend the exercise period for the vested stock options as a Type 1 modification. As a result, the incremental fair value of the modified options over the fair value of the original options on the modification date was calculated based on the assumptions in effect on November 12, 2021. The additional compensation cost totaling approximately $ 0.1 million was recognized in its entirety on November 12, 2021 since the modified share options are fully vested. The Company presented the impact of the modifications totaling approximately $ 0.5 million against the gain recognized upon the derecognition of the group of assets associated with the exosome manufacturing business that was transferred to Lonza.

Collaborative Arrangements

Collaborative Arrangements	12 Months Ended
	Dec. 31, 2021
Collaboration Agreements [Abstract]
Collaborative Arrangements	15. Collaboration agreements The following table summarizes the total consolidated net revenue from the strategic collaborators for the periods presented (in thousands): YEAR ENDED Collaboration Revenue by Strategic Collaborator: 2021 2020 Jazz $ 11,322 $ 641 Sarepta 11,613 2,274 Total collaboration revenue $ 22,935 $ 2,915 The following tables present changes in the Company’s contract assets and liabilities for the year ended December 31, 2021 (in thousands): YEAR ENDED DECEMBER 31, 2021 BALANCE ADDITIONS DEDUCTIONS BALANCE Contract assets: Account receivable (1) $ — $ 3,914 $ ( 3,286 ) $ 628 Contract liabilities: Deferred revenue $ 62,697 $ — $ ( 19,048 ) $ 43,649 (1) Included in prepaid expenses and other current assets as shown within the consolidated balance sheets. During the twelve months ended December 31, 2021 and 2020, the Company recognized the following revenue (in thousands): YEAR ENDED 2021 2020 Revenue recognized in the period from: Amounts included in deferred revenue at the beginning of the period $ 19,048 $ 641 Jazz collaboration and license agreement Agreement summary On January 2, 2019, the Company entered into a Collaboration and License Agreement (the Jazz Collaboration Agreement) with Jazz focused on the research, development and commercialization of exosome therapeutics to treat cancer. The Company granted Jazz an exclusive, worldwide, sublicensable, royalty-bearing license to develop, manufacture and commercialize therapeutic candidates directed at up to five oncogene targets (each, a Development and Commercialization License) to be developed using the Company’s engEx Platform for exosome therapeutics. The targets have been validated in hematological malignancies and solid tumors but generally have been undruggable with current modalities. On December 23, 2020, the Company and Jazz entered into an amendment to the Jazz Collaboration Agreement (the First Amendment). The First Amendment extended the time available for Jazz to exercise an option to July 2, 2021 with respect to either the inclusion of an additional target or initiation of an additional program. The First Amendment did not modify any of the other provisions of the Jazz Collaboration Agreement and did not result in any change in transaction price. Four of the targets were identified at the inception of the collaboration (the Initial Collaboration Targets) and on June 30 , 2021. As set forth in the Jazz Collaboration Agreement, early development will also include different engineered exosomes directed to the same target (each, a Backup Candidate). In April 2021, the Company and Jazz mutually agreed to discontinue their work on exoASO™-STAT3 (STAT3), one of the five oncogene targets subject to the Jazz Collaboration Agreement. On June 30, 2021, Jazz formally nominated the fifth collaboration target. Jazz also has the option to nominate an additional target (a Replacement Target) if two of the Initial Collaboration Targets fail prior to acceptance of an Investigational New Drug application (IND). In January 2022, the Company and Jazz mutually agreed to discontinue their work on the NRAS program. As a result of this discontinuation, Jazz may nominate a replacement target, subject to nomination requirements as outlined in the collaboration agreement. Codiak and Jazz continue to jointly advance their research and development efforts on other exosome-based therapeutic programs to treat cancer pursuant to the Jazz Collaboration Agreement. Under the terms of the Jazz Collaboration Agreement, the Company is responsible for the initial development of therapeutic candidates directed at all five targets as well as the costs associated with such development activities. In addition, the Company is responsible for development costs up to and including IND acceptance, and certain development costs of the Phase 1, Phase 1/2 and Phase 2 clinical trials for each of the first two therapeutic candidates to commence clinical trials. Following the conclusion of the applicable clinical trials for the first two candidates, and for the remaining three candidates, Jazz will be responsible for the further development and associated costs of the therapeutic candidates, including all Phase 3 and any Phase 4 clinical trials, potential regulatory submissions and commercialization for each product at its sole cost and expense. The Company has the option to participate in co-commercialization and cost/profit-sharing in the US and Canada on up to two products, subject to a one-time veto right by Jazz (which exercise of such veto may result in an additional $ 20.0 million milestone payment to the Company related to regulatory approval of the product). Should the Company choose to exercise this option, the Company and Jazz will equally split most of the remaining development costs and the net profits or losses in the US and Canada, while the Company would receive milestones and royalties for sales in other parts of the world. In the event that the Company does not exercise its option, the Company will receive milestones and royalties based upon sales worldwide. As part of the Jazz Collaboration Agreement, Jazz has paid the Company an up-front payment of $ 56.0 million. The Company is eligible to receive up to $ 20.0 million in preclinical development milestone payments, the first of which is for $ 10.0 million and will be due from Jazz upon the second initiation of IND-enabling toxicology studies for a collaboration target. The Company is also eligible to receive milestone payments totaling up to $ 200.0 million per product based on IND acceptance, clinical and regulatory milestones, including approvals in the US, the EU and Japan, and sales milestones. In addition, the Company will receive tiered royalties on net sales of each approved product, with percentages ranging from mid-single digits in the lowest tier to high teens in the highest tier, excluding such net sales in the US and Canada if the Company has exercised its option to co-commercialize the related product. The milestone and royalty payments are each subject to reduction under certain specified conditions set forth in the Jazz Collaboration Agreement, provided, however, that in the case of a termination with respect to a licensed compound that is a Development Candidate (as defined below), Jazz will maintain its obligation to reimburse the Company for certain development costs. Either party can terminate the agreement with respect to a region and a target upon the other party’s material breach relating to such region and target, subject to specified notice and cure provisions. Jazz also has the right to terminate the agreement in its entirety or in part (with respect to a particular collaboration target, research program, licensed compound or product, region or, in some cases, country) for convenience at any time upon 180 days ’ written notice or for safety reasons immediately upon notice, provided, however, that in the case of a termination for convenience with respect to a licensed compound that is a Development Candidate, Jazz will maintain its obligation to reimburse the Company for certain development costs. Absent early termination, the term of the Jazz Collaboration Agreement will continue on a country-by-country basis and licensed product-by-licensed product basis, until the expiration of the royalty payment obligations for the country and the licensed product (or, in the case of a shared territory for an optioned product, will continue for so long as such optioned product is being sold by Jazz or its affiliates or sublicensees in the shared territory). Any expiration or termination of the Jazz Collaboration Agreement does not affect the rights and obligations of the parties that accrued prior to the expiration or termination date. Upon termination of the Jazz Collaboration Agreement, all licenses granted by the Company to Jazz will immediately terminate. Accounting analysis The Company evaluated the Jazz Collaboration Agreement, as amended, in accordance with the provisions of ASC 606. The Company concluded that the contract counterparty is a customer in the arrangement. The Company accounted for the extension of the exercise period pursuant to the First Amendment as a modification. The Company did not account for the First Amendment as a separate contract because the amendment did not result in an increase to the scope of the arrangement nor was the pricing of the arrangement increased. Accordingly, the First Amendment was combined with the Jazz Collaboration Agreement. For the remaining promised goods and services that are distinct from the goods and services that were transferred on or before the date of the effectiveness of the First Amendment, the Company has accounted for the modification on a prospective basis as if it were a termination of the existing contract and the creation of a new contract. Conversely, the remaining promised goods and services that are not distinct from the goods and services that were transferred on or before the date of the effectiveness of the First Amendment were deemed to form part of a single performance obligation that is partially satisfied so they have been accounted for as part of the existing contract for which an adjustment has been recorded on a cumulative catch-up basis at the date of the modification. The Company determined that the change to the arrangement that was enacted by the First Amendment did not impact the identification of the promises in the contract. The Company’s obligations under the Jazz Collaboration Agreement, as amended, comprise the following substantive promises: • Development and Commercialization Licenses for each of the Initial Collaboration Targets (each, a Development and Commercialization License Promise) • Research services related to the conduct of the applicable work plan, which provides a framework for the applicable research activities, performed on a target-by-target basis, pursuant to a program aimed at identifying and evaluating exosome therapeutics directed to the individual targets (each such program for research activities, a Research Program) and sets forth the specific activities to be undertaken over the course of such Research Program, including the associated objectives and timelines therefor (each, a Work Plan) for each of the four Initial Collaboration Targets that are the subject of the collaboration (each, a Research Services Promise) • Preclinical and clinical services related to the completion of the Early Development Plans (as defined below) for each of the four Initial Collaboration Targets that are the subject of the collaboration (each, a Development Services Promise) • Material right associated with Jazz’s ability to obtain either: (i) a Development and Commercialization License, research services pursuant to an associated Work Plan, and preclinical and clinical services pursuant to an associated plan that describes the preclinical studies, manufacturing process development, and clinical development to be performed with respect to an applicable product candidate that the parties determine is suitable for IND-enabling studies (each such product candidate, a Development Candidate) and the associated timelines, budget and resource allocation therefor (each, an Early Development Plan) for an Additional Target or (ii) research services pursuant to an associated Work Plan and preclinical and clinical services pursuant to an associated Early Development Plan for an additional Research Program for one of the Initial Collaboration Targets (an Additional Research Program, and such material right, the Additional Target or Program Material Right Promise) • Material right associated with Jazz’s ability to obtain a Development and Commercialization License, research services pursuant to an associated Work Plan and preclinical and clinical services pursuant to an associated Early Development Plan for a Replacement Target (the Replacement Target Material Right Promise) • Material rights associated with Jazz’s ability to obtain services with respect to non-GLP toxicology studies for two Backup Candidates (each, a Backup Candidate Material Right Promise) For purposes of evaluating the Jazz Collaboration Agreement, as amended, in accordance with ASC 606, the Company has determined that the ability for Jazz to either nominate an Additional Target or request an Additional Research Program represents a material right because the pricing inherent in such option provides the customer with a discount that is incremental to the range of discounts that would otherwise be granted for the related goods and services to comparable customers. More specifically, the Development and Commercialization License and associated research services under the related Work Plan that would be provided pursuant to Jazz’s option to include an Additional Target within the scope of the arrangement would be provided at no additional cost to Jazz. Similarly, the research services under a Work Plan that would be provided upon an exercise of Jazz’s option to request an Additional Research Program would be provided at no additional cost to Jazz. The deadline for the exercise of this option was extended by a defined period of time under the First Amendment, but the option was otherwise unchanged. Additionally, the Company has determined that the ability for Jazz to elect a Replacement Target represents a material right because the pricing inherent in such option provides the customer with a discount that is incremental to the range of discounts that would otherwise be granted for the related goods and services to comparable customers. Consistent with an Additional Target, to the extent Jazz requests that a Replacement Target be included within the scope of the arrangement, the Development and Commercialization License and associated research services under the related Work Plan would be provided at no additional cost to Jazz. Lastly, the Company determined that the ability for Jazz to request the Company to render services with respect to non-GLP toxicology studies for certain Backup Candidates represents a material right because the pricing inherent in such option also provides the customer with a discount that is incremental to the range of discounts that would otherwise be granted for the related services to comparable customers. Along the same lines as the other material rights, upon Jazz’s exercise, the Company would render services with respect to the conduct of non-GLP toxicology studies for one Backup Candidate for each of the first two Development Candidates at no cost to Jazz. The Company determined that the extension of the exercise period pursuant to the First Amendment did not affect the composition of the performance obligations. For purposes of evaluating the Jazz Collaboration Agreement, as amended, in accordance with ASC 606, the Company determined that the Development and Commercialization License Promise for each of the Initial Collaboration Targets is neither capable of being distinct nor distinct within the context of the contract from the associated Research Services Promise and Development Services Promise. Due to the specialized nature of the services to be provided by the Company, specifically with respect to the Company’s proprietary expertise related to exosome engineering and manufacturing, the customer cannot benefit from or utilize the license without the research and development services. Moreover, the Company concluded that the Development and Commercialization License Promise, Research Services Promise and Development Services Promise for each individual target are interrelated to and interdependent on each other. Due to the nature of the services and capabilities of the parties, the customer cannot derive its intended benefit from the license without the accompanying research and development services to be performed pursuant to the underlying Work Plans and Early Development Plans. The nature of the combined performance obligation is to provide certain research and development services for targets that are designated for inclusion in the arrangement in order to transfer a combined item to the customer in the form of a product candidate for which human proof of concept has been established. As such, the Company has treated the Development and Commercialization License Promise, Research Services Promise and Development Services Promise related to each target as a combined performance obligation (each, a License and Services Performance Obligation; collectively, the License and Services Performance Obligations). However, the Company has determined that the License and Services Performance Obligation associated with each target is distinct from the License and Services Performance Obligation for the other targets because: (i) Jazz can benefit from the license and research and development services for a given target on their own since the results related thereto can be evaluated discretely and (ii) each bundle for an individual target is separately identifiable since it does not affect either the Company’s ability to perform or Jazz’s ability to assess the program for any other target. Thus, the License and Services Performance Obligation for each target is a separate performance obligation. Each of the material right promises has been deemed a distinct performance obligation due to their nature as specified in ASC 606. The Company has identified the following eight performance obligations in connection with its obligations under the Jazz Collaboration Agreement, as amended : • Combined performance obligation comprising the Development and Commercialization License Promise, Research Services Promise and Development Services Promise for each of the four Initial Collaboration Targets (the License and Services Performance Obligation: Initial Collaboration Target #1, License and Services Performance Obligation: Initial Collaboration Target #2, License and Services Performance Obligation: Initial Collaboration Target #3 and License and Services Performance Obligation: Initial Collaboration Target #4, respectively) • Material right associated with Jazz’s option to request either: (i) an Additional Target or (ii) an Additional Research Program (the Additional Target or Program Material Right Performance Obligation) • Material right associated with Jazz’s option to request a Replacement Target (the Replacement Target Material Right Performance Obligation) • Material right associated with Jazz’s option to request certain Backup Candidates (the Backup Candidate Material Right Performance Obligation: Backup Candidate #1 and Backup Candidate Material Right Performance Obligation: Backup Candidate #2, respectively) Accordingly, in accounting for the modification resulting from the First Amendment, the License and Services Performance Obligations were treated as part of the existing contract, whereas the material right performance obligations were treated as a termination of the existing contract and the creation of a new contract. At inception of the arrangement, the Company measured the transaction price solely in reference to the $ 56.0 million non-refundable and non-creditable up-front payment. None of the variable consideration payable under the arrangement was included in the transaction price at inception. The Company estimates the amount of variable consideration to which it expects to be entitled associated with cost reimbursements, in addition to preclinical development, IND acceptance, clinical and regulatory milestones, using the most likely amount method. The Company did not include any cost reimbursements in the transaction price at inception due to the uncertainty around the Company’s receipt of such amounts as it is dependent upon viable product candidates progressing through development. All preclinical development, IND acceptance, clinical and regulatory milestone payments were excluded from the transaction price at inception due to the uncertainty of initiating the specified phase of preclinical development, achieving the associated development criteria or receiving approval or acknowledgement from the relevant regulatory authorities. Further, regulatory milestone payments will be excluded from the transaction price until the associated regulatory milestone is achieved. The sales milestone payments, royalties and profit share are subject to the royalty recognition constraint because the associated license is deemed to be the sole or predominant item to which the payments relate. As of December 23, 2020, the total remaining consideration was $ 55.0 million which solely comprises the transaction price on the original contract not yet recognized as revenue because the modification did not change the arrangement consideration. The Company updates its assessment of the estimated transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur. There have been no changes to the Company’s estimate of variable consideration on active performance obligations since inception of the arrangement through December 31, 2021. As of December 31, 2021, the Company has not achieved any preclinical development, IND acceptance, clinical, regulatory or sales milestones or earned any royalties or profit share under the Jazz Collaboration Agreement. Upon modification, the Company allocated the transaction price associated with the remaining consideration to each of the identified performance obligations on a relative standalone selling price basis. Certain elements of variable consideration are attributable to specific performance obligations; however, no amounts of variable consideration have been included in the transaction price. The Company updated the standalone selling prices for each of the identified performance obligations to reflect assumptions and estimates in effect on the modification date. The Company determined the updated standalone selling prices for each of the performance obligations included in the Jazz Collaboration Agreement considering relevant market conditions, entity-specific factors and information about the customer, while maximizing the use of available observable inputs. As a result, the transaction price associated with the remaining consideration was reallocated to the identified performance obligations as follows (in thousands): PERFORMANCE OBLIGATION ALLOCATED License and Services Performance Obligation: Initial Collaboration Target #1 $ 12,717 License and Services Performance Obligation: Initial Collaboration Target #2 13,702 License and Services Performance Obligation: Initial Collaboration Target #3 10,866 License and Services Performance Obligation: Initial Collaboration Target #4 13,593 Additional Target or Program Material Right Performance Obligation 2,812 Replacement Target Material Right Performance Obligation 1,188 Backup Candidate Material Right Performance Obligation: Backup Candidate #1 47 Backup Candidate Material Right Performance Obligation: Backup Candidate #2 47 Transaction Price $ 54,972 The standalone selling price for each of the License and Services Performance Obligations was estimated using a hybrid approach whereby the standalone selling price for each of the Development and Commercialization License Promises was estimated using an income approach, while the standalone selling price of the Research Services Promises and Development Services Promises for each of the plans associated with the individual targets were estimated using an expected cost-plus margin approach. The discounted cash flow analysis utilized in deriving the estimated standalone selling price for each of the Development and Commercialization License Promises included such key assumptions as: development timeline, revenue forecast, discount rate and probabilities of technical and regulatory success. The cost-plus margin approach utilized in deriving the estimated standalone selling price for the Research Services Promises and Development Services Promises for each target was based on the estimate of the overall effort to perform the underlying Work Plans and Early Development Plans and an estimated market rate for the associated services. The standalone selling prices for the Additional Target or Program Material Right Performance Obligation and Replacement Target Material Right Performance Obligation were estimated based on a similar hybrid approach as the License and Services Performance Obligations, but also contemplated the discount the customer could receive without exercising the corresponding option and the likelihood that the respective option will be exercised. The standalone selling price for the Additional Target or Program Material Right Performance Obligation also reflects the likelihood that each of the alternatives will be selected by Jazz. Lastly, the standalone selling prices for the Backup Candidate Material Right Performance Obligations was estimated using an expected cost-plus margin approach based on the estimate of the overall effort to perform the associated non-GLP toxicology studies. Amounts allocated to each of the License and Services Performance Obligations is recognized as revenue over time commensurate with the term of the associated Research Program and development activities performed pursuant to a program focused on establishing human proof-of-concept for a given target using a proportional performance model which depicts the Company’s performance in transferring control to the customer. The Company utilizes a cost-based input method to measure progress because such method best reflects the satisfaction of the performance obligation as the underlying services are provided. In applying the cost-based input method of revenue recognition, the Company uses actual costs incurred relative to the budgeted costs to complete each of the respective programs. These costs consist primarily of internal full-time equivalent effort and third-party costs. Allocated amounts are recognized as revenue based on actual costs incurred as a percentage of total budgeted costs. A cost-based input method of revenue recognition requires management to make estimates of costs to complete the Company’s performance obligations. In making such estimates, significant judgment is required to evaluate assumptions related to cost estimates. The cumulative effect of revisions to estimated costs to complete the programs is recorded in the period in which changes are identified and amounts can be reasonably estimated. A significant change in these assumptions and estimates could have a material impact on the timing and amount of revenue recognized in future periods. During 2021, the Company and Jazz mutually agreed to discontinue their work on STAT3, one of five oncogene targets subject to the Jazz Collaboration Agreement. Jazz maintains a license to the STAT3 program and has the contractual right to revive it to an active target in the future. T he Company recognized the remaining $ 10.9 million in deferred revenue allocated to this target during twelve months ended December 31, 2021 . On June 30, 2021, Jazz formally nominated the fifth collaboration target. The Company will recognize the $ 2.8 million of revenue allocated to this performance obligation consistent with all active Jazz targets, recording revenue based on actual costs incurred relative to the budgeted costs to complete each of the respective programs. As of December 31, 2021, there are three remaining material rights outstanding under the Jazz Collaboration Agreement. In January 2022, the Company and Jazz mutually agreed to discontinue their work on NRAS. The Company classified the remaining $ 12.6 million deferred revenue allocated to this target to short-term during the 12 months ended December 31, 2021, and the Company will recognize this as revenue in the first quarter of 2022, as a result of the discontinuation. As of December 31, 2021, with the exception of NRAS, there were no significant changes in the Company's assumptions or estimates related to the costs to complete. Amounts allocated to each of the Additional Target or Program Material Right Performance Obligation, Replacement Target Material Right Performance Obligation and Backup Candidate Material Right Performance Obligations will continue to be recognized as revenue upon the earlier of when: (i) the option is exercised wherein the future goods and/or services are transferred or (ii) the option expires. As of December 31, 2021, all of the material rights are outstanding as none of the material rights have been exercised or have expired. The aggregate amount of the transaction price allocated to the License and Services Performance Obligations that were unsatisfied, as of December 31, 2020 was $ 50.9 million, which is expected to be recognized over the respective term of the associated Research Program and development activities for each target, through approximately 2026. The aggregate amount of the transaction price allocated to all other performance obligations that were unsatisfied as of December 31, 2020 was $ 4.1 million, which is expected to be recognized upon the earlier of when the respective option is exercised or expires. During the twelve months ended December 31, 2021 and 2020, the Company recognized $ 11.3 million and $ 0.6 million of revenue under the Jazz Collaboration Agreement, respectively. The aggregate amount of the transaction price allocated to the License and Services Performance Obligations that were unsatisfied, as of December 31, 2021 wa s $ 39.6 million, which is expected to be recognized over the respective term of the associated Research Program and development activities for each target, through approximately 2026. The aggregate amount of the transaction price allocated to all other performance obligations that were unsatisfied as of December 31, 2021 was $ 4.1 million, which is expected to be recognized upon the earlier of when the respective option is exercised or expires. As of December 31, 2021 and 2020 , the Company had $ 43.7 million and $ 55.0 million, respectively, of deferred revenue related to the Company’s collaboration with Jazz which is classified as current or long-term in the accompanying consolidated balance sheets based on the expected timing of satisfaction of the underlying goods and/or services. During the years ended December 31, 2021 and 2020 , the Company incurred $ 2.5 million and $ 3.3 million of costs associated with its obligations under the arrangement with Jazz which is classified within research and development expenses in the accompanying consolidated statements of operations and comprehensive loss Sarepta license and option agreement Agreement summary On June 17, 2020, the Company entered into a two-year Research License and Option Agreement (the Sarepta Research Agreement) with Sarepta focused on the use of exosomes for non-viral delivery of AAV, gene-editing and RNA therapeutics to address five agreed targets associated with neuromuscular diseases. Pursuant to the Sarepta Research Agreement, the Company received funding to conduct collaborative research and Sarepta had options to enter into exclusive, worldwide licenses for each of the agreed targets to develop, commercialize and manufacture therapeutic candidates developed using the Company’s engEx Platform. For each target option exercised, the Company would have been eligible to receive an option exercise fee, milestones and royalties. Each target was well-understood to be therapeutically relevant to its associated neuromuscular disease. Either party had the right to terminate the Sarepta Research Agreement upon the other party’s material breach, subject to specified notice and cure provisions. Sarepta also had the right to terminate the Sarepta Research Agreement in its entirety or in part (with respect to a particular target) for convenience at any time upon specified written notice, subject to an obligation to pay the Company’s related personnel costs for a specified period of time after the effective date of termination as well as to pay for any unavoidable costs as a result of the termination. Expiration or termination of the Sarepta Research Agreement would not affect the rights and obligations of the parties that accrued prior to the expiration or termination date. Upon termination of the Sarepta Research Agreement, the license and options granted by the Company to Sarepta would immediately terminate. On October 1, 2021, Sarepta notified the Company that it was terminating early the two-year Research License and Option Agreement, dated June 17, 2020, between Sarepta and the Company. The termination was effective as of D

Other Significant Agreements

Other Significant Agreements	12 Months Ended
	Dec. 31, 2021
Significant Agreements [Abstract]
Other Significant Agreements	16. Other significant agreements MDACC sponsored research agreement In November 2015, the Company entered into the MDACC Research Agreement with MDACC. Under the MDACC Research Agreement, the Company engaged MDACC to perform research and development services relating to its technology on patients suffering with cancer (the Research Program). MDACC was obligated to use reasonable efforts to conduct the Research Program and furnish the facilities necessary to carry out the program. The Research Program allowed for amendments from time to time during the term, by agreement of the parties, to modify the current Research Program or to add additional research projects for inclusion as part of the Research Program. The MDACC Research Agreement provided the Company with an option to negotiate a license to certain other technology derived from the program in the field of exosome technology. The term of the MDACC Research Agreement was originally scheduled to expire in November 2018. The MDACC Research Agreement was subsequently amended in February 2017 and in April 2018 to extend the term of the MDACC Research Agreement to February 2021 and to modify the payment terms of the MDACC Research Agreement. The MDACC Research Agreement was further amended in September 2019 to terminate the agreement, effective as of December 31, 2019. Under the terms of the MDACC Research Agreement, the Company was obligated to pay fixed tiered quarterly cash payments (the Quarterly Payments) and to issue a fixed number of shares of its Series A Preferred Stock or Series B Preferred Stock to MDACC in consideration for the research services. The Quarterly Payments consisted of the following: (i) direct expenses comprising $ 1.0 million payable to MDACC in the first year and $ 1.25 million payable in years two through five, and (ii) overhead charges of 25 % of the direct expenses. In addition to the Quarterly Payments, the Company was also obligated to issue an aggregate of 200,000 shares of Series A Preferred Stock in the first year of the arrangement and 20,833 shares of Series B Preferred Stock, quarterly, in years two through five of the MDACC Research Agreement. The Company recognized the payments made to MDACC as research and development expense as incurred. The shares to be issued were expensed on the date the associated Quarterly Payment was due based on the estimated fair value of the underlying series of Redeemable Convertible Preferred Stock on such date. Subsequent to issuance, the Series A Preferred Stock and Series B Preferred Stock issued to MDACC was accounted for consistent with all other outstanding shares of the respective series of Redeemable Convertible Preferred Stock. As no ted above, the agreement was terminated as of December 31, 2019 . As of December 31, 2019, the Company accrued the final $ 1.2 million cash payment and 62,500 shares of Series B Preferred Stock related to services provided in 2019. The Company made the final cash payment and issued the remaining shares of Series B Preferred Stock to MDACC in January 2020. There are no further payments or share issuances owed to MDACC pursuant to the MDACC Research Agreement. There was no expense recognized during the year ended December 31, 2021 or 2020 related to the MDACC Research Agreement. MDACC in-license agreement In November 2015, the Company entered into a Patent and Technology License Agreement with MDACC, as amended in April 2018 (the MDACC License Agreement). Pursuant to the MDACC License Agreement, the Company holds exclusive worldwide license rights to certain intellectual property relating to the use of exosomes for diagnostic and therapeutic applications and a non-exclusive worldwide license under certain related technologies, with the right to grant sublicenses. The Company also obtained the exclusive right of first negotiation, for a specified time period, for a license to certain of MDACC’s rights in future exosome technology. Under the terms of the MDACC License Agreement, the Company is responsible for all patent costs incurred by MDACC for the underlying licensed technology in excess of $ 1.5 million from the effective date of the agreement through February 1, 2021, and for all patent costs incurred or invoiced after this date. As of December 31, 2021 , there was no remaining funding provided by MDACC for patent-related costs under the MDACC License Agreement. Pursuant to the MDACC License Agreement, the Company is also required to make future payments to MDACC upon the occurrence of events related to the development of products and upon the achievement of certain development and regulatory approval milestones up to an aggregate of $ 11.9 million, comprising up to $ 2.4 million for diagnostic products and up to $ 9.5 million for therapeutic products. The Company may at its discretion pay up to $ 4.4 million in such contingent payments in cash or through the issuance of equity in the form of redeemable convertible preferred stock or common stock, as applicable. Such payments will be expensed or capitalized based on the nature of the associated asset at the date the related contingency is resolved. In addition, the Company is obligated to pay certain payments upon the execution of sublicenses for qualifying products, as well as single digit percentage royalty payments on net sales from a licensed product. The MDACC License Agreement will continue until the last to occur of: (i) the expiration of all patents issued underlying the licenses conveyed, (ii) the cancellation, withdrawal or express abandonment of all patent rights underlying the licenses conveyed or (iii) the fifteenth anniversary of the effective date of the agreement. Upon expiration of the MDACC License Agreement, the licenses granted will automatically convert to a fully-paid irrevocable and perpetual license. The Company may terminate the license for convenience upon 180 days prior written notice to MDACC. The license automatically terminates upon the Company’s bankruptcy, if the Company challenges the validity or enforceability of any of the licensed patent rights, or if the Company fails to make a number of payments in a timely manner over a specified period of time. Additionally, MDACC may terminate the license for the Company’s breach subject to certain specified cure periods. As of December 31, 2021 , no milestones had been achieved, nor had any royalties, sublicensing fees or other contingent payments been incurred under the MDACC License Agreement. The Company did no t make any payments to MDACC for the years ended December 31, 2021 or 2020, with respect to the MDACC License Agreement. Kayla Therapeutics S.A.S license agreement On November 6, 2018, the Company entered into a License Agreement with Kayla, pursuant to which it obtained a co-exclusive worldwide, sublicensable license under certain patent rights and to related know-how and methods to research, develop, manufacture and commercialize compounds and products covered by such patent rights in all diagnostic, prophylactic and therapeutic uses (the Kayla License Agreement). The foregoing license is co-exclusive with Kayla, but Kayla’s retained rights are subject to certain restrictions. During the first six years following the effective date of the Kayla License Agreement, Kayla and its affiliates may not research, develop, manufacture or commercialize anywhere in the world any product containing a small molecule STING agonist and an exosome. In addition, during the term of the Kayla License Agreement, Kayla and its affiliates may not grant a license to any third party under the licensed patent rights to, develop, manufacture or commercialize anywhere in the world a product containing certain STING compounds for therapeutic or veterinary purpose. The Kayla License Agreement also restricts the Company from developing any competing product containing a small molecule STING agonist and an exosome until the expiration of a non-compete period determined by the achievement of clinical milestones. Pursuant to ASC 730, the Company determined that the assets acquired represent in-process research and development with no alternative future use. Therefore, the value of the consideration given for the licenses was expensed to acquired in-process research and development in the period in which it was incurred. In consideration for entering into the Kayla License Agreement, the Company paid an up-front payment of $ 6.5 million in cash and issued 118,212 shares of common stock. The Company recorded an aggregate of $ 8.1 million to acquired in-process research and development expense during the year ended December 31, 2018 comprising: (i) $ 6.5 million related to the cash payment and (ii) $ 1.6 million related to the issuance of its common stock based on the fair value of the Company’s common stock at the effective date of the Kayla License Agreement. The Company has certain diligence obligations under the Kayla License Agreement, which include using commercially reasonable efforts to develop, commercialize and market the products developed under the licensed patent rights, including using commercially reasonable efforts to initiate a cohort extension of a Phase 1/2 trial after obtaining IND approval. The Company is also obligated to pay up to $ 100.0 million in cash payments and up to $ 13.0 million payable in shares of the Company’s common stock upon the achievement of specified clinical and regulatory milestones, including approvals in the US, the EU and Japan. Such payments will be expensed or capitalized based on the nature of the associated asset at the date the related contingency is resolved. Additionally, the Company is obligated to pay to Kayla a percentage of the payments that the Company receives from sublicensees of the rights licensed to it by Kayla, excluding any royalties. This percentage varies from single digits to low double digits. The first milestone was achieved upon the dosing of the first subject in the Company’s exoSTING Phase 1/2 clinical trial in September 2020. Upon achievement of the milestone, the Company was obligated to make a nonrefundable payment of $ 15.0 million in cash and issue 177,318 shares of common stock to Kayla. The common stock was issued as of the date of dosing, and the cash payment of $ 15.0 million was paid as of December 31, 2020. As of December 31, 2021 , no other milestones had been achieved. The Company is obligated to pay to Kayla tiered royalties ranging from low single-digits to mid-single-digits based on annual net sales by the Company, its affiliates and its sublicensees of licensed products. The royalty term is determined on a product-by-product and country-by-country basis and continues until the later of (i) the expiration of the last valid claim of the licensed patent rights that covers such product in such country, (ii) the loss or expiration of any period of marketing exclusivity for such product in such country, or (iii) ten years after the first commercial sale of such product in such country; provided that if the royalty is payable when no valid claim covers a given product in a given country, the royalty rate for sales of such product in such country is decreased. The Company may terminate the Kayla License Agreement on a licensed compound-by-licensed compound basis and on a region-by region basis for any reason upon 30 days prior written notice to Kayla. The Company or Kayla may terminate the Kayla License Agreement for the other’s material breach that remains uncured for 60 days after receiving notice thereof. As of December 31, 2021, no royalties, or other contingent payments had been incurred under the Kayla License Agreement.

401(k) Plan

401(k) Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
401(k) Plan	17. 401(k) plan The Company has a defined contribution savings plan under Section 401(k) of the Internal Revenue Code. This plan covers substantially all employees who meet minimum age and service requirements and allows participants to defer a portion of their annual compensation on a pre-tax basis. The Company matches 50 % of the first 6 % of an employee’s deferral. The Company’s contributions are expensed in the year for which they are declared. For the year ended December 31, 2021 and 2020, the Company recorded expense of $ 0.6 million and $ 0.4 million, respectively, for 401(k) match contributions.

Net Loss Per Share

Net Loss Per Share	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	18. Net loss per share Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): YEAR ENDED 2021 2020 Numerator: Net loss $ ( 37,157 ) $ ( 91,665 ) Cumulative dividends on redeemable convertible — ( 10,831 ) Net loss attributable to common stockholders $ ( 37,157 ) $ ( 102,496 ) Denominator: Weighted average common shares outstanding, basic 21,794,546 6,332,841 Net loss per share attributable to common stockholders, $ ( 1.70 ) $ ( 16.18 ) As of December 31, 2021 and 2020, we had 4,763,489 and 4,543,318 outstanding stock options, respectively, representing potential common shares, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have been anti-dilutive.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	19. Income taxes During the years ended December 31, 2021 and 2020, the Company recorded no income tax benefits for the net operating losses incurred and research and development tax credits earned in each year or interim period due to its uncertainty of realizing a benefit from those items. The reconciliation of the US statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2021 and 2020 is as follows: YEAR ENDED DECEMBER 31, 2021 2020 Federal statutory income tax rate 21.0 % 21.0 % State taxes, net of federal benefit 8.5 7.4 Federal and state research and development credits 5.9 2.7 Executive Compensation ( 0.7 ) ( 0.3 ) Non-deductible items ( 0.1 ) ( 0.1 ) Stock Compensation ( 1.5 ) ( 0.8 ) Change in valuation allowance ( 33.2 ) ( 30.0 ) Other 0.1 0.1 Effective income tax rate — % — % Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets and liabilities consisted of the following (in thousands): YEAR ENDED DECEMBER 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 51,672 $ 37,609 Capitalized license and research and development payments 7,786 8,393 Research and development credits 15,062 11,910 Deferred revenue 11,919 17,117 Lease Liabilities 10,105 10,519 Accrued bonus 1,085 1,053 Stock compensation 4,344 3,335 Other temporary differences 289 349 Total deferred tax assets 102,262 90,285 Valuation allowance ( 93,091 ) ( 80,758 ) Deferred tax assets 9,171 9,527 Deferred tax liabilities: Right of use asset ( 5,996 ) ( 6,007 ) Depreciation ( 3,175 ) ( 3,520 ) Net deferred taxes $ — $ — As of December 31, 2021, the Company had federal and state net operating loss carryforwards of $ 189.4 million and $ 188.7 million, respectively, which may be available to offset future taxable income. The Company has generated federal net operating losses of $ 152.9 million which have an indefinite carryforward period. The remaining $ 36.4 million of federal net operating loss carryforwards and the Company’s state net operating loss carryforwards would begin to expire in 2035 . As of December 31, 2021, the Company had federal and state research and development credit carryforwards of $ 10.5 million an d $ 5.0 million , respectively, which may be available to offset future income tax liabilities and which would begin to expire in 2035 and 2031 , respectively. Th e federal and state income tax returns are generally subject to tax examinations for the tax years ending December 31, 2018 through 2021. To the extent the Company has tax attribute carryforwards, the tax years in which the attribute was generated may still be adjusted upon examination by the Internal Revenue Service, state or foreign tax authorities to the extent utilized in a future period. The Company has evaluated the positive and negative evidence bearing upon its ability to realize the deferred tax assets. Management has considered the Company’s cumulative net losses and its lack of commercialization of any products or generation of any revenue from product sales since inception and has concluded that it is more likely than not that the Company will not realize the benefits of the deferred tax assets. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2021 and 2020. Management reevaluates the positive and negative evidence at each reporting period. Changes in the valuation allowance for deferred tax assets during the years ended December 31, 2021 and 2020 were prim arily due to the increases in net operating loss and tax credit carryforwards and totaled $ 12.3 million and $ 27.5 million, respectively. The Company has no t recorded any amounts for unrecognized tax benefits as of December 31, 2021 or 2020. The Company does not have any uncertain tax positions. The Company has not conducted a study of its research and development credit carryforwards. This study may result in an adjustment to research and development credit carryforwards; however, until a study is completed and any adjustment is known, no amounts are being presented as an uncertain tax position. A full valuation allowance has been provided against the Company’s research and development credits and, if an adjustment is required, this adjustment would be offset by an adjustment to the valuation allowance. Thus, there would be no impact to the consolidated balance sheet or statement of operations if an adjustment were required. The Company files tax returns as prescribed by the tax laws of the jurisdictions in which it operates. Net operating losses are subject to review and possible adjustment by the Internal Revenue Service and state tax authorities. Net operating loss carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions. This could limit the amount of tax attributes that can be utilized annually to offset future taxable income or tax liabilities. The amount of the annual limitation is determined based on the value of the company immediately prior to the ownership change. Subsequent ownership changes may further affect the limitation in future years. The Company has not yet conducted a study to determine if any such changes have occurred that could limit its ability to use the net operating losses and tax credit carryforwards. It is the Company’s policy to include penalties and interest expense related to income taxes as a component of income tax expense, as necessary. As of December 31, 2021 or 2020, the Company had no accrued interest or penalties related to uncertain tax positions and no amounts have been recognized in the Company’s consolidated statements of operations and comprehensive loss.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation and Principles of Consolidation	Basis of presentation and principles of consolidation The Company's consolidated financial statements are prepared in accordance with U.S. generally accepted accounting principles (GAAP). Any reference in these notes to applicable guidance is meant to refer to the authoritative accounting principles generally accepted in the United States as found in the Accounting Standard Codification (ASC) and Accounting Standards Update (ASU) of the Financial Accounting Standards Board (FASB). The accompanying consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Codiak Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation.
Use of Estimates	Use of estimates We have made estimates and judgments affecting the amounts reported in our consolidated financial statements and the accompanying notes. On an ongoing basis, we evaluate our estimates, including critical accounting policies or estimates related to revenue recognition, stock-based compensation, accrued expenses, leases, gain upon derecognition, contingent consideration and the long-lived lives of useful assets. We base our estimates on historical experience and various relevant assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. The actual results that we experience may differ materially from our estimates. Significant estimates relied upon in preparing these financial statements include, among others, those related to the fair value of equity awards, revenue recognition, accrued expenses, leases, gain upon derecognition, contingent consideration, income taxes, and long-lived lives of useful assets.
Segment	Segments The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of assessing performance and allocating resources. All of the Company’s long-lived assets are held in the United States.
Disposition of Business	Disposition of Business The Company accounts for the derecognition of a group of assets that is a business in transactions with noncustomers in accordance with ASC 810-10-40. The Company measures the gain or loss upon derecognition as the difference between: (i) aggregate fair value of any consideration received and (ii) carrying amount of the group of assets, net of transaction and other costs directly attributable to the transaction. Gains and losses are recognized as of the date the Company ceases to have a controlling financial interest in the associated group of assets. Consideration received, including contingent consideration, is initially measured at fair value. Contingent consideration is subsequently remeasured by recognizing increases using a gain contingency approach and impairments based on the loss contingency model. Both the fair value of the consideration received and any potential future contingent gains contain unobservable inputs, whereby expected future cash flows are discounted using a rate that includes assumptions regarding an entity’s average cost of debt and equity, incorporates expected future cash flows based on internal business plans, and applies certain assumptions about risk and uncertainties.
Cash, Cash Equivalents and Restricted Cash	Cash, cash equivalents and restricted cash The Company considers all highly liquid investments purchased with original final maturities of three months or less from the date of purchase to be cash equivalents. Cash equivalents comprises money market accounts invested in US Treasury securities. Restricted cash is composed of letters of credit held as collateral related to the Company’s lease arrangements. Restricted cash is classified as either current or non-current based on the term of the underlying lease agreement.
Investments	Investments The Company classifies all of its investments as available-for-sale securities. The Company’s investments are measured and reported at fair value using quoted prices in active markets for similar securities. Unrealized gains and losses on available-for-sale securities are reported as accumulated other comprehensive (loss) income, which is a separate component of stockholders’ equity (deficit). The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense), net within the consolidated statements of operations and comprehensive loss. If any adjustment to fair value reflects a decline in the value of the investment that the Company considers to be “other than temporary”, the Company reduces the investment to fair value through a charge to the consolidated statements of operations and comprehensive loss. No such adjustments were necessary during the periods presented. The Company classifies its available-for-sale investments as current assets on the consolidated balance sheets if they mature within one year from the balance sheet date. Those investments with maturities greater than 12 months would be considered non-current. Investments with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets.
Deferred Offering Costs	Deferred offering costs The Company capitalizes certain legal, accounting and other third-party fees that are directly associated with in-process equity financings as deferred offering costs until such financings are consummated. Such costs are classified in prepaid expenses and other current assets in the accompanying consolidated balance sheets. After the consummation of the equity financing, these costs are recorded in stockholders’ equity (deficit) as a reduction of additional paid-in capital or the associated preferred stock account, as applicable. In the event the offering is terminated, all capitalized deferred offering costs are expensed. Deferred offering costs as of December 31, 2021 were $ 0.2 million in connection with the Company's shelf registration and “at-the-market” offering facility. Deferred offering costs as of December 31, 2020 were $ 0.2 million in connection with the follow-on equity funding completed in February 2021.
Concentrations of Credit Risk and Significant Suppliers and License Agreements	Concentrations of credit risk and significant suppliers and license agreements Financial instruments that potentially expose the Company to credit risk primarily consist of cash, cash equivalents, restricted cash and investments. The Company maintains its cash, cash equivalent, restricted cash and investment balances with accredited financial institutions and, consequently, the Company does not believe it is subject to unusual credit risk beyond the normal credit risk associated with commercial banking relationships. The Company’s cash management and investment policy limits investment instruments to investment-grade securities with the objective to preserve capital and to maintain liquidity until the funds can be used in business operations. Bank accounts in the United States are insured by the Federal Deposit Insurance Corporation (FDIC) up to $ 250,000 . As of December 31, 2021 and 2020, the Company’s primary operating accounts significantly exceeded the FDIC limits. The Company is presently dependent on third-party manufacturers to supply materials for research and development activities of its programs, including clinical and preclinical testing. The Company’s development programs could be adversely affected by a significant interruption in the supply of the necessary materials. The Company is also dependent on third parties who provide license rights used in the development of certain programs. The Company could experience delays in the development of its programs if any of these license agreements are terminated, if the Company fails to meet the obligations required under its arrangements, or if the Company is unable to successfully secure new strategic alliances or licensing agreements. For the year ended December 31, 2021, Jazz accounted fo r 49 % of total collaboration revenue and Sarepta accounted for 51 % of total collaboration revenue. For the year ended December 31, 2020, Jazz accounted for 22 % of total collaboration revenue and Sarepta accounted for 78 % of tot al collaboration revenue.
Off-Balance-Sheet Risk	Off-balance sheet risk As of December 31, 2021 and 2020, the Company had no off-balance sheet risks such as foreign exchange contracts, option contracts or other foreign hedging arrangements.
Fair Value of Financial Instruments	Fair value of financial instruments The Company is required to disclose information on all assets and liabilities reported at fair value that enables an assessment of the inputs used in determining the reported fair values. FASB ASC Topic 820, Fair Value Measurements and Disclosures (ASC 820), establishes a hierarchy of inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that the observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing the asset or liability based on market data obtained from sources independent of the Company. Unobservable inputs are inputs that reflect the Company’s assumptions about the inputs that market participants would use in pricing the asset or liability and are developed based on the best information available in the circumstances. The fair value hierarchy applies only to the valuation inputs used in determining the reported fair value of the investments and is not a measure of the investment credit quality. The three levels of the fair value hierarchy are described below: Level 1 — Valuations based on quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. Level 2 — Valuations based on quoted prices for similar assets or liabilities in markets that are not active or for which all significant inputs are observable, either directly or indirectly. Level 3 —Valuations that require inputs that reflect the Company’s own assumptions that are both significant to the fair value measurement and unobservable. To the extent that valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. Items measured at fair value on a recurring basis include cash equivalents as of December 31, 2021 and 2020 . Certain cash equivalents that are measured at fair value using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy. The carrying amounts reflected in the consolidated balance sheets for prepaid expenses and other current assets, accounts payable and accrued expenses approximate their fair values due to their short-term maturities.
Property and Equipment	Property and equipment Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated useful life Computer equipment and software 3 years Furniture and fixtures 5 years Laboratory and manufacturing equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term Purchased assets that are not yet in service are recorded to construction-in-progress and no depreciation expense is recorded. Once they are placed in service they are reclassified to the appropriate asset class and depreciated over their respective estimated useful lives. Upon the retirement or sale of an asset, the related cost and accumulated depreciation or amortization is removed from the accounts and any resulting gain or loss is recorded to other income (expense), net. Expenditures for maintenance and repairs are expensed as incurred.
Impairment of Long-Lived Assets	Impairment of long-lived assets The Company periodically evaluates its long-lived assets, which consist of property and equipment, prepaid manufacturing services and right-of-use-assets, for impairment whenever events or changes in circumstances indicate that a potential impairment may have occurred. If such events or changes in circumstances arise, the Company compares the carrying amount of the long-lived assets to the estimated future undiscounted cash flows expected to be generated by the long-lived assets. If the estimated aggregate undiscounted cash flows are less than the carrying amount of the long-lived assets, an impairment charge, calculated as the amount by which the carrying amount of the assets exceeds the fair value of the assets, is recorded. The fair value of the long-lived assets is determined based on the estimated discounted cash flows expected to be generated from the long-lived assets. The Company has no t recorded any such impairment charges during the years ended December 31, 2021 or 2020 .
Term Loan	Term loan The Company accounts for its Loan and Security Agreement with Hercules as a liability measured at net proceeds less debt discount and is accreted to the associated face value of the term loan over its respective expected term using the effective interest method. The Company considers whether there are any embedded features in its debt instruments that require bifurcation and separate accounting as derivative financial instruments pursuant to FASB ASC Topic 815, Derivatives and Hedging . The Company capitalizes certain legal and other third-party fees that are directly associated with obtaining access to capital under credit facilities. Deferred financing costs related to a recognized debt liability are recorded as a reduction of the carrying amount of the debt liability and amortized to interest expense using the effective interest rate method. Deferred financing costs related to the term loan were less than $ 0.1 million for the years ended December 31, 2021 and 2020, respectively.
Leases	Leases The Company accounts for leases in accordance with ASC 842, Leases . Leases are classified at their commencement date, which is defined as the date on which the lessor makes the underlying asset available for use by the lessee, as either operating or finance leases based on the economic substance of the agreement. Lease liabilities are measured at the lease commencement date as the present value of the future lease payments using the interest rate implicit in the lease. If the rate implicit is not readily determinable, the Company will utilize their incremental borrowing rate as of the lease commencement date. If the rate implicit is not readily determinable, the Company will utilize their incremental borrowing rate as of the lease commencement date. Lease right-of-use assets are measured as the lease liability plus initial direct costs and prepaid lease payments less lease incentives. The lease term is the non-cancelable period of the lease, adjusted for any options to extend or terminate when it is reasonably certain the Company will exercise such options. The Company does not recognize leases with an initial term of 12 months or less. The Company’s operating leases are presented in the consolidated balance sheets as operating lease right-of-use assets, classified as noncurrent assets, and operating lease liabilities, classified as current and noncurrent liabilities based on the portion of the lease liability that will mature within the proceeding twelve months. Operating lease expense for the minimum lease payments is recognized on a straight-line basis over the lease term. The Company assesses its right-of-use assets for impairment consistent with the assessment performed for long-lived assets used in operations. The Company evaluates its subleases in which it is the sublessor to determine whether it is relieved of the primary obligation under the original lease. If it remains the primary obligor, the Company continues to account for the original lease as it did before the commencement of the sublease and reports the sublease income on a gross basis in other income in the consolidated statements of operations and comprehensive loss.
Redeemable Convertible Preferred Stock	Redeemable convertible preferred stock Prior to the automatic conversion of all outstanding shares of the Company’s redeemable convertible preferred stock upon the closing of the IPO, the Company recorded all redeemable convertible preferred stock upon issuance at its respective fair value or original issuance price less issuance costs. The Company classified its redeemable convertible preferred stock outside of stockholders’ equity (deficit) as the redemption of such shares was outside the Company’s control. The Company adjusted the carrying values of the redeemable convertible preferred stock to redemption value when the redemption value exceeded the carrying value. As of December 31, 2021 and 2020, the Company did no t have any convertible preferred stock issued or outstanding.
Revenue Recognition	Revenue recognition The Company recognizes revenue in accordance with FASB ASC Topic 606, Revenue from Contracts with Customers (ASC 606). The core principle of ASC 606 is that an entity should recognize revenue to depict the transfer of promised goods and/or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods and/or services. To determine the appropriate amount of revenue to be recognized, the Company performs the following steps: (i) identify the contract(s) with the customer, (ii) identify the performance obligations in the contract, (iii) determine the transaction price, (iv) allocate the transaction price to the performance obligations in the contract and (v) recognize revenue when (or as) each performance obligation is satisfied. Pursuant to the guidance in ASC 606, the Company accounts for a contract with a customer that is within the scope of ASC 606 when all of the following criteria are met: (i) the arrangement has been approved by the parties and the parties are committed to perform their respective obligations, (ii) each party’s rights regarding the goods and/or services to be transferred can be identified, (iii) the payment terms for the goods and/or services to be transferred can be identified, (iv) the arrangement has commercial substance and (v) collection of substantially all of the consideration to which the Company will be entitled in exchange for the goods and/or services that will be transferred to the customer is probable. The Company assesses the goods and/or services promised within a contract which contains multiple promises to evaluate which promises are distinct. Promises are considered to be distinct and therefore, accounted for as separate performance obligations, provided that: (i) the customer can benefit from the good or service either on its own or together with other resources that are readily available to the customer and (ii) the promise to transfer the good or service to the customer is separately identifiable from other promises in the contract. The Company determines that a customer can benefit from a good or service if it could be used, consumed, sold for an amount that is greater than scrap value, or otherwise held in a way that generates economic benefits. Factors that are considered in determining whether or not two or more promises are not separately identifiable include, but are not limited to, the following: (i) the Company provides a significant service of integrating goods and/or services with other goods and/or services promised in the contract, (ii) one or more of the goods and/or services significantly modifies or customizes, or are significantly modified or customized by, one or more of the other goods and/or services promised in the contract and (iii) the goods and/or services are highly interdependent or highly interrelated. Individual goods or services (or bundles of goods and/or services) that meet both criteria for being distinct are accounted for as separate performance obligations. Promises that are not distinct at contract inception are combined into a single performance obligation. Options to acquire additional goods and/or services are evaluated to determine if such option provides a material right to the customer that it would not have received without entering into the contract. If so, the option is accounted for as a separate performance obligation. If not, the option is considered a marketing offer which would be accounted for as a separate contract upon the customer’s election. The terms of the Company’s arrangements include the payment of one or more of the following: (i) non-refundable, up-front fees, (ii) cost reimbursements, (iii) development, regulatory and commercial milestone payments, (iv) royalties on net sales of licensed products and (v) profit share for co-commercialized products. The transaction price generally comprises of fixed fees due at contract inception and an estimate of variable consideration for cost reimbursements and milestone payments due upon the achievement of specified events. Additionally, the Company may earn sales milestones, tiered royalties earned when the licensee recognizes net sales of licensed products and potentially profit share related to co-commercialized products. The Company measures the transaction price based on the amount of consideration to which it expects to be entitled in exchange for transferring the promised goods and/or services to the customer. The Company utilizes either the expected value method or the most likely amount method to estimate the amount of variable consideration, depending on which method is expected to better predict the amount of consideration to which it will be entitled. Amounts of variable consideration are included in the transaction price to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur when the uncertainty associated with the variable consideration is subsequently resolved. With respect to development and regulatory milestone payments, at the inception of the arrangement, the Company evaluates whether the associated event is considered probable of achievement and estimates the amount to be included in the transaction price using the most likely amount method. As part of the evaluation for development milestone payments, the Company considers several factors, including the stage of development of the targets included in the arrangement, the risk associated with the remaining development work required to achieve the milestone and whether or not the achievement of the milestone is within the Company’s control. Milestone payments that are not within the control of the Company or the licensee, such as those dependent upon receipt of regulatory approval, are not considered to be probable of achievement until the triggering event occurs. With respect to sales-based royalties and profit share payments, including milestone payments based upon the achievement of a certain level of product sales, wherein the license is deemed to be the sole or predominant item to which the payments relate, the Company recognizes revenue upon the later of: (i) when the related sales occur or (ii) when the performance obligation to which some or all of the payment has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any development, regulatory or commercial milestones, royalty or profit share revenue resulting from its arrangements with customers. The Company considered the existence of a significant financing component in its arrangements and has determined that a significant financing component does not exist due to the applicability of available practical expedients, existence of substantive business purposes and/or presence of other compelling factors. The Company updates its assessment of the estimated transaction price, including the constraint on variable consideration, at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur. Any adjustments to the transaction price are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. The Company generally allocates the transaction price to each performance obligation identified in the contract on a relative standalone selling price basis. However, certain components of variable consideration are allocated specifically to one or more particular performance obligations to the extent both of the following criteria are met: (i) the terms of the payment relate specifically to the efforts to satisfy the performance obligation or transfer the distinct good or service and (ii) allocating the variable amount of consideration entirely to the performance obligation or the distinct good or service is consistent with the allocation objective of the standard whereby the amount allocated depicts the amount of consideration to which the entity expects to be entitled in exchange for transferring the promised goods or services. The Company develops assumptions that require judgment to determine the standalone selling price for each performance obligation identified in the contract. The key assumptions utilized in determining the standalone selling price for the performance obligations may include forecasted revenues, development timelines, estimated research and development costs, discount rates, other comparable transactions, likelihood of exercise and probabilities of technical and regulatory success. Revenue is recognized based on the amount of the transaction price that is allocated to each respective performance obligation when or as the performance obligation is satisfied by transferring a promised good and/or service to the customer. For performance obligations that are satisfied at a point in time, the Company recognizes revenue when control of the goods and/or services is transferred to the customer. For performance obligations that are satisfied over time, the Company recognizes revenue by measuring the progress toward complete satisfaction of the performance obligation using a single method of measuring progress which depicts the performance in transferring control of the associated goods and/or services to the customer. The Company generally uses input methods to measure the progress toward the complete satisfaction of performance obligations satisfied over time. With respect to promises related to licenses to intellectual property that is determined to be distinct from the other performance obligations identified in the arrangement, the Company recognizes revenue from amounts allocated to the license when the license is transferred to the licensee and the licensee is able to use and benefit from the license. For licenses that are bundled with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenue and net loss in the period of adjustment. The Company receives payments from its licensees in accordance with the terms of the contracts. Up-front payments and fees are recorded as contract liabilities upon receipt or when due and may require deferral of revenue recognition to a future period until the Company performs its obligations under the arrangement. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified in current liabilities. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as contract liabilities, net of current portion. Amounts payable to the Company are recorded as accounts receivable when the Company’s right to consideration is unconditional.
Research and Development Expense	Research and development expense Research and development costs are expensed as incurred. Research and development expenses consist of costs incurred in performing research and development activities, including salaries and benefits, overhead costs, contract services and other related costs. The value of goods and services received from contract research organizations and contract manufacturing organizations in the reporting period are estimated based on the level of services performed, and progress in the period in cases when the Company has not received an invoice from the supplier. In circumstances where amounts have been paid in excess of costs incurred, the Company records a prepaid expense.
Patent Costs	Patent costs Costs to secure, defend and maintain patents are expensed as incurred due to the uncertainty of future benefits and are classified as general and administrative expenses.
Stock-Based Compensation	Stock-based compensation The Company issues stock-based awards to employees and non-employees, generally in the form of stock options and restricted stock units (RSUs). The Company accounts for stock-based compensation awards in accordance with ASC 718, Compensation—Stock Compensation. Most of its stock-based awards have been made to employees. The Company measures compensation cost for equity awards at their grant-date fair value and recognize compensation expense over the requisite service period, which is generally the vesting period, on a straight-line basis. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model, which requires management to make assumptions with respect to the fair value of the common stock on the grant date, including the expected term of the award, the expected volatility of the stock, calculated based on a period of time generally commensurate with the expected term of the award, risk-free interest rates and expected dividend yields of the stock. Historically, for periods prior to the IPO, the fair value of the shares of common stock and common units underlying our stock-based awards were determined on each grant date by the board of directors based on valuation estimates from management considering our most recently available independent third-party valuation of the common stock. The board of directors also assessed and considered, with input from management, additional objective and subjective factors that it believed were relevant and which may have changed from the date of the most recent valuation through the grant date. The grant date fair value of RSUs is estimated based on the fair value of the underlying common stock. For performance-based stock awards, The Company recognizes stock-based compensation expense over the requisite service period using the accelerated attribution method when achievement is probable. The Company classifies stock-based compensation expense in its consolidated statement of operations in the same manner in which the award recipient’s salary and related costs are classified or in which the award recipient’s service payments are classified. The Company uses the simplified method prescribed by Securities and Exchange Commission Staff Accounting Bulletin No. 107, Share-Based Payment , to calculate the expected term of options granted to employees, non-employees and directors. The risk-free interest rate is determined by reference to the U.S. Treasury yield curve in effect at the time of grant of the award for time periods approximately equal to the expected term of the award. Expected dividend yield is based on the fact that the Company has never paid cash dividends and does not expect to pay any cash dividends in the foreseeable future.
Income Taxes	Income taxes Income taxes are recorded in accordance with FASB ASC Topic 740, Income Taxes (ASC 740), which provides for deferred taxes using an asset and liability approach. The Company recognizes deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements or tax returns. Deferred tax assets and liabilities are determined based on the difference between the financial statement and tax basis of assets and liabilities using enacted tax rates in effect for the year in which the differences are expected to reverse. Valuation allowances are provided if, based upon the weight of available evidence, it is more likely than not that some or all of the deferred tax assets will not be realized. The Company makes estimates and judgments about future taxable income based on assumptions that are consistent with the Company’s plans and estimates. Should the actual amounts differ from these estimates, the amount of the Company’s valuation allowance could be materially impacted. Changes in these estimates may result in significant increases or decreases to the tax provision in a period in which such estimates are changed, which in turn would affect net income or loss. The Company accounts for uncertain tax positions in accordance with the provisions of ASC 740. When uncertain tax positions exist, the Company recognizes the tax benefit to the extent that the position is more likely than not to be sustained on examination by the taxing authorities based on the technical merits of the position as well as consideration of the available facts and circumstances. The Company records interest and penalties related to uncertain tax positions, if applicable, as a component of income tax expense.
Comprehensive Loss	Comprehensive loss Comprehensive loss includes net loss as well as other changes in stockholders’ equity (deficit) that result from transactions and economic events other than those with stockholders. For the year ended December 31, 2020, other comprehensive (loss) income included unrealized gains and losses on investments. The Company did no t have any other comprehensive (loss) income for the year ended December 31, 2021.
Net Loss Per Share	Net loss per share The Company follows the two-class method when computing net loss per share attributable to common stockholders as the Company has issued shares that meet the definition of participating securities. The two-class method determines net loss per share for each class of common and participating securities according to dividends declared or accumulated and participation rights in undistributed earnings. The two-class method requires losses for the period to be allocated between common and participating securities based upon their respective rights to share in the earnings as if all losses for the period had been distributed. During periods of loss, there is no allocation required under the two-class method since the participating securities do not have a contractual obligation to fund the losses of the Company. Basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, which excludes shares of restricted common stock that are not vested. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted average number of common shares outstanding for the period, including the effect of potentially dilutive common shares. For purpose of this calculation, outstanding options to purchase shares of common stock, unvested shares of restricted common stock and shares of redeemable convertible preferred stock are considered potentially dilutive common shares. The Company has generated a net loss in all periods presented so the basic and diluted net loss per share attributable to common stockholders are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive.
Emerging Growth Company Status	Emerging growth company status The Company is an “emerging growth company”, or EGC, as defined in the Jumpstart Our Business Startups Act (JOBS Act), and may take advantage of certain exemptions from various reporting requirements that are applicable to other public companies that are not EGCs. The Company may take advantage of these exemptions until it is no longer an EGC under Section 107 of the JOBS Act, which provides that an EGC can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to use the extended transition period for complying with new or revised accounting standards, and as a result of this election, the consolidated financial statements may not be comparable to companies that comply with public company FASB standards’ effective dates. The Company may take advantage of these exemptions up until the last day of the fiscal year following the fifth anniversary of an offering or such earlier time that it is no longer an EGC.
Recent Accounting Pronouncements	Recent accounting pronouncements Recently issued accounting pronouncements not yet adopted From time to time, new accounting pronouncements are issued by the FASB or other standard setting bodies and adopted by the Company as of the specified effective date. Unless otherwise discussed, the Company believes that the impact of recently issued standards that are not yet effective will not have a material impact on its financial position or results of operations upon adoption. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses: Measurement of Credit Losses on Financial Instruments. The new standard amends the current financial instrument impairment model by requiring entities to use a forward-looking approach based on expected losses to estimate credit losses on certain types of financial instruments, including trade receivables. The new standard will be effective for the Company on January 1, 2023. The adoption of this standard is not expected to have a material impact on the Company’s financial position or results of operations. In December 2019, the FASB issued ASU No. 2019-12 Income Taxes (Topic 740)-Simplifying the Accounting for Income Taxes (ASU 2019-12), as part of its initiative to reduce complexity in the accounting standards. The amendments in ASU 2019-12 eliminates certain exceptions related to the approach for intraperiod tax allocation, the methodology for calculating income taxes in an interim period and the recognition of deferred tax liabilities for outside basis differences. ASU 2019-12 also clarifies and simplifies other aspects of the accounting for income taxes. ASU 2019-12 is effective for the Company on January 1, 2022. The Company is currently evaluating the potential impact that this standard may have on its financial position and results of operations.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Property and Equipment Estimated Useful Lives	Property and equipment is stated at cost, net of accumulated depreciation and amortization. Depreciation and amortization is calculated using the straight-line method over the estimated useful lives of the assets, which are as follows: Estimated useful life Computer equipment and software 3 years Furniture and fixtures 5 years Laboratory and manufacturing equipment 5 years Leasehold improvements Shorter of useful life or remaining lease term

Derecognition of Business (Tabl

Derecognition of Business (Tables)	12 Months Ended
	Dec. 31, 2021
Discontinued Operations and Disposal Groups [Abstract]
Summary of Calculation of Gain Recognized upon Derecognition of Group of Assets Transferred	Below is the calculation of the gain recognized upon derecognition of the group of assets that transferred to Lonza on November 15, 2021: Element Amount Fair value of consideration $ 39,170 Carrying amount of assets transferred ( 4,823 ) Transaction costs ( 526 ) Share-based payment modification expense ( 535 ) Gain on derecognition $ 33,286

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Assets Measured at Fair Value on a Recurring Basis	The following tables present information about the Company’s assets measured at fair value on a recurring basis, and indicate the level of the fair value hierarchy utilized to determine such fair values (in thousands): DECEMBER 31, 2021 TOTAL LEVEL 1 LEVEL 2 LEVEL 3 NOT Assets: Cash equivalents: Money market funds $ 67,603 $ — $ — $ — $ 67,603 $ 67,603 $ — $ — $ — $ 67,603 DECEMBER 31, 2020 TOTAL LEVEL 1 LEVEL 2 LEVEL 3 NOT Assets: Cash equivalents: Money market funds $ 81,601 $ — $ — $ — $ 81,601 $ 81,601 $ — $ — $ — $ 81,601 (1) Certain cash equivalents that are valued using the net asset value per share (or its equivalent) practical expedient have not been classified in the fair value hierarchy.

Prepaids and Other Current As_2

Prepaids and Other Current Assets (Tables)	12 Months Ended
	Dec. 31, 2021
Prepaid Expense and Other Assets, Current [Abstract]
Components of Prepaid and Other Current Assets	Prepaid expenses and other current assets consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Clinical trial costs $ 1,053 $ 805 Prepaid insurance 2,593 2,598 Other receivables 1,289 31 Other prepaid expenses and other current assets 983 1,308 $ 5,918 $ 4,742

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	12 Months Ended
	Dec. 31, 2021
Property Plant And Equipment [Abstract]
Schedule of Property and Equipment, Net	Property and equipment, net, consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Leasehold improvements $ 21,691 $ 23,949 Laboratory equipment 11,898 14,837 Furniture and fixtures 1,208 1,288 Computer equipment and software 119 159 Construction-in-process 372 1,667 $ 35,288 $ 41,900 Less: Accumulated depreciation and amortization ( 11,809 ) ( 10,490 ) Property and equipment, net $ 23,479 $ 31,410

Accrued Expenses (Tables)

Accrued Expenses (Tables)	12 Months Ended
	Dec. 31, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses	Accrued expenses consisted of the following (in thousands): DECEMBER 31, DECEMBER 31, Accrued employee compensation $ 5,142 $ 5,040 Accrued external research and development costs 2,420 1,475 Accrued professional services and consulting 1,523 902 Accrued facilities costs 190 846 Other expenditures 428 607 $ 9,703 $ 8,870

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Components of Operating Lease Costs	The components of operating lease costs were as follows (in thousands): FOR THE YEAR ENDED DECEMBER 31, 2021 2020 Operating lease costs $ 4,882 $ 4,836 Short-term lease costs 27 19 Variable lease costs 2,582 2,222 Sublease income ( 1,850 ) ( 861 ) $ 5,641 $ 6,216
Summary of Additional Lease Information	Additional lease information is summarized in the following table (in millions, except lease term and discount rate): FOR THE YEAR ENDED DECEMBER 31, 2021 2020 Cash paid for amounts included in the measurement of operating $ 6.0 $ 6.0 Weighted-average remaining lease term - operating leases (years) 7.9 8.9 Weighted-average discount rate - operating leases 10.1 % 10.3 %
Schedule of Undiscounted Cash Flows Used in Calculating the Operating Lease Liabilities and Amounts to be Received under the Sublease	Undiscounted cash flows used in calculating the Company’s operating lease liabilities and amounts to be received under the sublease at 35 CambridgePark Drive and 4 Hartwell Place as of December 31, 2021 are as follows (in thousands): Fiscal Year OPERATING SUBLEASE NET 2022 $ 6,252 $ 2,821 $ 3,431 2023 6,436 1,962 4,474 2024 6,625 936 5,689 2025 6,820 6,820 2026 7,020 7,020 Thereafter 21,779 21,779 Total undiscounted cash flows $ 54,932 $ 5,719 $ 49,213 Less: Amounts representing interest ( 17,387 ) Present value of lease liabilities $ 37,545

Indebtedness (Tables)

Indebtedness (Tables)	12 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Future Principal Payments	The future principal payments under the Loan Agreement are as follows as of December 31, 2021 (in thousands): Fiscal Year PRINCIPAL 2022 $ - 2023 2,773 2024 11,680 2025 10,547 $ 25,000

Common Stock (Tables)

Common Stock (Tables)	12 Months Ended
	Dec. 31, 2021
Stockholders' Equity Note [Abstract]
Shares of Common Stock Reserved for Future Issuance	DECEMBER 31, DECEMBER 31, Common stock reserved for exercises of outstanding stock options issued 4,763,489 4,543,318 Common stock reserved for future issuances 1,573,353 1,288,891 6,336,842 5,832,209

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2021
Summary of Stock Option Activity	The following table summarizes the Company’s stock option activity during the twelve months ended December 31, 2021: NUMBER WEIGHTED WEIGHTED AGGREGATE (In years) (In thousands) Outstanding as of December 31, 2020 4,543,318 $ 8.52 7.22 $ 108,048 Granted 1,449,400 23.26 Exercised ( 433,751 ) 8.62 Forfeited/Cancelled ( 795,478 ) 11.10 Outstanding as of December 31, 2021 4,763,489 12.56 6.44 10,370 Exercisable as of December 31, 2021 2,688,532 8.02 5.41 9,372 Vested and expected to vest as of December 31, 2021 4,763,489 12.56 6.44 10,370 (1) Aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock as of December 31, 2021 and 2020 .
Schedule of Components and Classification of Stock-Based Compensation Expense	The following table presents the components and classification of stock-based compensation expense (in thousands): YEAR ENDED 2021 2020 Research and development $ 4,733 $ 3,563 General and administrative 5,409 3,517 Gain on disposition 535 - $ 10,677 $ 7,080 Employee $ 9,862 $ 6,547 Non-employee 815 533 $ 10,677 $ 7,080
Service-Based Awards
Summary of Key Assumptions Used for Stock Option Valuation	The key assumptions used in the Black-Scholes option pricing model on the date of grant for options with service-based vesting conditions granted to employees, directors and non-employees, were as follows, presented on a weighted average basis: YEAR ENDED 2021 2020 Risk-free interest rate 0.83 % 0.68 % Expected term (in years) 6.20 6.18 Expected volatility 68.21 % 68.75 % Expected dividend yield 0.00 % 0.00 % Fair value per share of common stock $ 14.37 $ 13.52

Collaborative Arrangements (Tab

Collaborative Arrangements (Tables)	12 Months Ended
	Dec. 31, 2021
Summary of Total Consolidated Net Revenue from Strategic Collaborators	The following table summarizes the total consolidated net revenue from the strategic collaborators for the periods presented (in thousands): YEAR ENDED Collaboration Revenue by Strategic Collaborator: 2021 2020 Jazz $ 11,322 $ 641 Sarepta 11,613 2,274 Total collaboration revenue $ 22,935 $ 2,915
Schedule of Changes in Contract Assets and Liabilities	The following tables present changes in the Company’s contract assets and liabilities for the year ended December 31, 2021 (in thousands): YEAR ENDED DECEMBER 31, 2021 BALANCE ADDITIONS DEDUCTIONS BALANCE Contract assets: Account receivable (1) $ — $ 3,914 $ ( 3,286 ) $ 628 Contract liabilities: Deferred revenue $ 62,697 $ — $ ( 19,048 ) $ 43,649 (1) Included in prepaid expenses and other current assets as shown within the consolidated balance sheets.
Schedule of Revenue Recognized	During the twelve months ended December 31, 2021 and 2020, the Company recognized the following revenue (in thousands): YEAR ENDED 2021 2020 Revenue recognized in the period from: Amounts included in deferred revenue at the beginning of the period $ 19,048 $ 641
Jazz Pharmaceuticals Ireland Limited
Schedule of Transaction Price Allocated to Identified Performance Obligations	As a result, the transaction price associated with the remaining consideration was reallocated to the identified performance obligations as follows (in thousands): PERFORMANCE OBLIGATION ALLOCATED License and Services Performance Obligation: Initial Collaboration Target #1 $ 12,717 License and Services Performance Obligation: Initial Collaboration Target #2 13,702 License and Services Performance Obligation: Initial Collaboration Target #3 10,866 License and Services Performance Obligation: Initial Collaboration Target #4 13,593 Additional Target or Program Material Right Performance Obligation 2,812 Replacement Target Material Right Performance Obligation 1,188 Backup Candidate Material Right Performance Obligation: Backup Candidate #1 47 Backup Candidate Material Right Performance Obligation: Backup Candidate #2 47 Transaction Price $ 54,972
Sarepta Therapeutics
Schedule of Transaction Price Allocated to Identified Performance Obligations	As a result, the transaction price was allocated to the identified performance obligations as follows: PERFORMANCE OBLIGATION ALLOCATED Research License and Services Performance Obligation $ 11,000 Material Right Performance Obligation: Research Target #1 1,400 Material Right Performance Obligation: Research Target #2 1,400 Material Right Performance Obligation: Research Target #3 1,400 Material Right Performance Obligation: Research Target #4 1,400 Material Right Performance Obligation: Research Target #5 1,400 Transaction Price $ 18,000

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	12 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Basic and Diluted Net Loss Per Share Attributable to Common Stockholders	Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share data): YEAR ENDED 2021 2020 Numerator: Net loss $ ( 37,157 ) $ ( 91,665 ) Cumulative dividends on redeemable convertible — ( 10,831 ) Net loss attributable to common stockholders $ ( 37,157 ) $ ( 102,496 ) Denominator: Weighted average common shares outstanding, basic 21,794,546 6,332,841 Net loss per share attributable to common stockholders, $ ( 1.70 ) $ ( 16.18 )

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Summary of Reconciliation of US Statutory Income Tax Rate to the Company's Effective Tax Rate	The reconciliation of the US statutory income tax rate to the Company’s effective tax rate for the years ended December 31, 2021 and 2020 is as follows: YEAR ENDED DECEMBER 31, 2021 2020 Federal statutory income tax rate 21.0 % 21.0 % State taxes, net of federal benefit 8.5 7.4 Federal and state research and development credits 5.9 2.7 Executive Compensation ( 0.7 ) ( 0.3 ) Non-deductible items ( 0.1 ) ( 0.1 ) Stock Compensation ( 1.5 ) ( 0.8 ) Change in valuation allowance ( 33.2 ) ( 30.0 ) Other 0.1 0.1 Effective income tax rate — % — %
Summary of Significant Components of Company's Deferred Tax Assets and Liabilities	Deferred taxes are recognized for temporary differences between the basis of assets and liabilities for financial statement and income tax purposes. The significant components of the Company’s deferred tax assets and liabilities consisted of the following (in thousands): YEAR ENDED DECEMBER 31, 2021 2020 Deferred tax assets: Net operating loss carryforwards $ 51,672 $ 37,609 Capitalized license and research and development payments 7,786 8,393 Research and development credits 15,062 11,910 Deferred revenue 11,919 17,117 Lease Liabilities 10,105 10,519 Accrued bonus 1,085 1,053 Stock compensation 4,344 3,335 Other temporary differences 289 349 Total deferred tax assets 102,262 90,285 Valuation allowance ( 93,091 ) ( 80,758 ) Deferred tax assets 9,171 9,527 Deferred tax liabilities: Right of use asset ( 5,996 ) ( 6,007 ) Depreciation ( 3,175 ) ( 3,520 ) Net deferred taxes $ — $ —

Nature of the Business - Additi

Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	Feb. 17, 2021	Oct. 16, 2020	Dec. 31, 2021	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Entity date of incorporation			Jun. 12, 2015
Common stock, shares issued and sold	3,162,500	5,500,000
Common stock, offering price	$ 21	$ 15
Net proceeds from issuance of common stock	$ 61,700	$ 74,400	$ 61,674	$ 74,351
Additional Common stock, shares issued	412,500
Issuance of redeemable convertible preferred stock			168,200
Net of issuance costs			24,600
Payments from its collaborations			66,000
Cash and cash equivalents			$ 76,900
Substantial Doubt about Going Concern, within One Year [true false]			true
Substantial doubt about going concern, description			The Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about its ability to continue as a going concern within one year after the date that the consolidated financial statements are issued.

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Dec. 31, 2021USD ($)Segmentshares	Dec. 31, 2020USD ($)shares
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments | Segment	1
Other-than-temporary fair value adjustments of available-for-sale securities, recognized in earnings	$ 0	$ 0
Deferred offering costs	200,000	200,000
Off-balance sheet risks, assets	0	0
Off-balance sheet risks, liabilities	0	0
Impairment charges recorded on long-lived assets	0	0
Other comprehensive (loss) income	$ 0	$ (43,000)
Convertible preferred stock issued | shares	0	0
Convertible preferred stock outstanding | shares	0	0
Construction In Progress
Summary Of Significant Accounting Policies [Line Items]
Depreciation expense	$ 0
Revenue Benchmark | Jazz Pharmaceuticals Ireland Limited | Revenue from Rights Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	49.00%	22.00%
Revenue Benchmark | Sarepta Therapeutics | Revenue from Rights Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage	51.00%	78.00%
Maximum
Summary Of Significant Accounting Policies [Line Items]
FDIC insured amount	$ 250,000	$ 250,000
Maximum | Term Loan
Summary Of Significant Accounting Policies [Line Items]
Deferred financing costs	$ 100,000	$ 100,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Property and Equipment Estimated Useful Lives (Details)	12 Months Ended
	Dec. 31, 2021
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property and equipment, Estimated useful life	3 years
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property and equipment, Estimated useful life	5 years
Laboratory and Manufacturing Equipment
Property Plant And Equipment [Line Items]
Property and equipment, Estimated useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, Estimated useful life	Shorter of useful life or remaining lease term

Derecognition of Business - Add

Derecognition of Business - Additional Information (Details) - Lonza - USD ($)	Nov. 15, 2021	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Aggregate fair value of non-cash consideration	$ 39,200,000
Asset Purchase Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration transactions	$ 65,000,000
Manufacturing Services Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Clinical program period	4 years
Agreement termination advance notice period	12 months
License and Collaboration Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Sublicense revenue		$ 0
Sublease Agreement
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Lease commencement date	Nov. 15, 2021
Lease expiration date	Nov. 30, 2024
Annual fixed rent charges	$ 1,000,000
Percentage of annual increase in fixed rent charges	2.80%

Derecognition of Business - Sum

Derecognition of Business - Summary of Calculation of Gain Recognized upon Derecognition of Group of Assets Transferred (Details) - Lonza $ in Thousands	Nov. 15, 2021USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Fair value of consideration	$ 39,170
Carrying amount of assets transferred	(4,823)
Transaction costs	(526)
Share-based payment modification expense	(535)
Gain on derecognition	$ 33,286

Fair Value Measurements - Asset

Fair Value Measurements - Assets Measured at Fair Value on a Recurring Basis (Details) - Recurring Basis - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Assets:
Assets	$ 67,603	$ 81,601
Money Market Funds
Assets:
Cash equivalents	67,603	81,601
Not Subject to Netting
Assets:
Assets	67,603	81,601
Not Subject to Netting | Money Market Funds
Assets:
Cash equivalents	$ 67,603	$ 81,601

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Assets transfer, Level 1 to 2	$ 0	$ 0
Assets transfer, Level 2 to 1	0	0
Assets transfer, out of Level 3	0	0
Assets transfer, into Level 3	$ 0	$ 0

Investments - Additional Inform

Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Available-for-sale investments	$ 0
Realized gains or losses	$ 0
Maximum
Debt Securities, Available-for-sale [Line Items]
Realized gains or losses		$ 100,000

Prepaids and Other Current As_3

Prepaids and Other Current Assets - Components of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Prepaid Expense and Other Assets, Current [Abstract]
Clinical trial costs	$ 1,053	$ 805
Prepaid Insurance	2,593	2,598
Other receivables	1,289	31
Other prepaid expenses and other current assets	983	1,308
Prepaid Expense and Other Assets, Current	$ 5,918	$ 4,742

Property and Equipment, Net - S

Property and Equipment, Net - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 35,288	$ 41,900
Less: Accumulated depreciation and amortization	(11,809)	(10,490)
Property and equipment, net	23,479	31,410
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	21,691	23,949
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	11,898	14,837
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	1,208	1,288
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	119	159
Construction-In-Process
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 372	$ 1,667

Property and Equipment, Net - A

Property and Equipment, Net - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Depreciation and amortization expense	$ 5,500	$ 4,400
Gain on disposition	33,286
Maximum
Property Plant And Equipment [Line Items]
Leasehold Improvements Write off	100
Laboratory Equipment
Property Plant And Equipment [Line Items]
Gain on disposition	$ 4,800

Restricted Cash - Additional In

Restricted Cash - Additional Information (Details) $ in Millions	Dec. 31, 2021USD ($)
Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 4.2

Accrued Expenses - Schedule of

Accrued Expenses - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee compensation	$ 5,142	$ 5,040
Accrued external research and development costs	2,420	1,475
Accrued professional services and consulting	1,523	902
Accrued facilities costs	190	846
Other expenditures	428	607
Accrued expenses	$ 9,703	$ 8,870

Leases - Additional Information

Leases - Additional Information (Details)	Nov. 15, 2021USD ($)Renewal	Jul. 01, 2021	Apr. 27, 2020USD ($)ft²	Aug. 26, 2019	Mar. 22, 2019USD ($)ft²	Mar. 05, 2019USD ($)ft²	Dec. 31, 2021USD ($)ft²Office	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Lessee Lease Description [Line Items]
Lease expiration year							2029
Number of location | Office							2
Operating right-of-use assets obtained in exchange for operating lease liabilities							$ 1,034,000	$ 23,186,000
Sublease income							$ 1,850,000	861,000
500 Technology Square
Lessee Lease Description [Line Items]
Area of lease | ft²							19,823
Lease, base rent per year							$ 1,500,000
Increase in annual rent percentage							2.50%
Lease commencement date							Dec. 28, 2016
Original lease expiration date							Dec. 31, 2021
Accelerated lease expiration date				Feb. 28, 2020
4 Hartwell Place
Lessee Lease Description [Line Items]
Area of lease | ft²						18,707
Lease, base rent per year						$ 900,000
Increase in annual rent percentage						2.60%
Lease expiration month and year						2029-12
Lease commencement month and year						2019-07
Lessee, operating lease, existence of option to extend [true false]						true
Lessee, operating lease, option to extend							The Company has the option to extend the lease twice, each for a five-year period, on the same terms and conditions as the current lease, subject to a change in base rent based on market rates.
Lessee, operating lease, option to extend term						5 years
Tenant improvement allowance, received							$ 1,300,000
Increase in base rent	$ 100,000
Initial direct cost	0
Operating right-of-use assets obtained in exchange for operating lease liabilities	1,000,000
Sublease payments to be received annually	$ 1,000,000
Sublease income, increase in annual percentage	2.80%
Sublease commencement date	Nov. 15, 2021
Sublease income expiration date	Nov. 30, 2024
Lessee, operating sublease, existence of option to extend	true
Lessee, operating sublease, option to extend							Lonza has the option to extend the sublease term for five 12-month periods on the same terms and conditions as the current sublease, subject to an increase of 2.8% in the annual fixed rent charges.
Number of operating sublease renewal term | Renewal	5
Lessee, operating sublease, option to extend term	12 months
Percentage of annual increase in fixed rent charges	2.80%
4 Hartwell Place | Maximum
Lessee Lease Description [Line Items]
Tenant improvement allowance						$ 1,300,000
4 Hartwell Place | Letter of Credit
Lessee Lease Description [Line Items]
Security deposit							$ 400,000	400,000
35 Cambridge Park Drive
Lessee Lease Description [Line Items]
Area of lease | ft²					68,258
Lease, base rent per year					$ 4,900,000
Increase in annual rent percentage					3.00%
Lease commencement date					Mar. 26, 2019
Lease expiration month and year					2029-11
Lessee, operating lease, existence of option to extend [true false]					true
Lessee, operating lease, option to extend							The Company has the option to extend the lease for a 10-year period on the same terms and conditions as the current lease, subject to a change in base rent based on market rates.
Lessee, operating lease, option to extend term					10 years
Tenant improvement allowance					$ 12,300,000
Tenant improvement allowance, received								12,300,000
Construction oversight fee					2.00%
Area of space for sublease | ft²			23,280
Sublease payments to be received annually			$ 1,300,000
Sublease income, increase in annual percentage			3.00%
Sublease commencement date			May 18, 2020
Sublease expiration month and year		2023-05	2022-05				2023-05
Lessee, operating sublease, existence of option to extend		true	true
Lessee, operating sublease, option to extend							The sublessee had the option to extend the sublease for a one-year period on the same terms and conditions as the current sublease, subject to a change in base rent based on the greater of (i) an increase of 3% of the annual rent owed by the sublessee in year two, and (ii) market rent for the subleased premises.
Lessee, operating sublease, option to extend term		1 year	1 year
35 Cambridge Park Drive | Letter of Credit
Lessee Lease Description [Line Items]
Security deposit								$ 3,700,000	$ 3,700,000
Security deposit in connection with sublease			$ 300,000

Leases - Components of Operatin

Leases - Components of Operating Lease Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lease, Cost [Abstract]
Operating lease costs	$ 4,882	$ 4,836
Short-term lease costs	27	19
Variable lease costs	2,582	2,222
Sublease income	(1,850)	(861)
Lease, cost	$ 5,641	$ 6,216

Leases - Summary of Additional

Leases - Summary of Additional Lease Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Cash paid for amounts included in the measurement of operating lease liabilities	$ 6	$ 6
Weighted-average remaining lease term - operating leases (years)	7 years 10 months 24 days	8 years 10 months 24 days
Weighted-average discount rate - operating leases	10.10%	10.30%

Leases - Schedule of Undiscount

Leases - Schedule of Undiscounted Cash Flows Used in Calculating the Operating Lease Liabilities and Amounts to be Received under the Sublease (Details) $ in Thousands	Dec. 31, 2021USD ($)
Leases [Abstract]
Operating Lease Payments, 2022	$ 6,252
Operating Lease Payments, 2023	6,436
Operating Lease Payments, 2024	6,625
Operating Lease Payments, 2025	6,820
Operating Lease Payments, 2026	7,020
Operating Lease Payments, Thereafter	21,779
Operating Lease Payments, Total undiscounted cash flows	54,932
Operating Lease Payments, Less: Amounts representing interest	(17,387)
Operating Lease Payments, Present value of lease liabilities	37,545
Sublease Receipts, 2022	2,821
Sublease Receipts, 2023	1,962
Sublease Receipts, 2024	936
Sublease Receipts, Total undiscounted cash flows	5,719
Net Operating Lease Payments, 2022	3,431
Net Operating Lease Payments, 2023	4,474
Net Operating Lease Payments, 2024	5,689
Net Operating Lease Payments, 2025	6,820
Net Operating Lease Payments, 2026	7,020
Net Operating Lease Payments, Thereafter	21,779
Net Operating Lease Payments, Total undiscounted cash flows	$ 49,213

Commitments and contingencies -

Commitments and contingencies - Additional Information (Details) - USD ($)	Nov. 15, 2021	Jan. 31, 2020	Sep. 30, 2020	Dec. 31, 2021	Dec. 31, 2020
Commitments And Contingencies [Line Items]
Issuance of common stock, net of issuance costs				$ 61,681,000	$ 74,352,000
License Agreement | Kayla Therapeutics S.A.S
Commitments And Contingencies [Line Items]
Nonrefundable payment in cash			$ 15,000,000
Nonrefundable payment in shares of common stock			177,318
Nonrefundable cash payment paid					$ 15,000,000
MD Anderson Cancer Center | Research Agreement | Series B Redeemable Convertible Preferred Stock
Commitments And Contingencies [Line Items]
Issuance of common stock, net of issuance costs		$ 1,200,000
Lonza | Manufacturing Services Agreement
Commitments And Contingencies [Line Items]
Cancellation fees and other charges				0
Minimum non-cancelable purchase obligation				$ 0
Agreement termination advance notice period	12 months

Indebtedness - Additional Infor

Indebtedness - Additional Information (Details)	Sep. 17, 2021USD ($)	Jul. 24, 2020USD ($)	Sep. 30, 2019USD ($)Tranche	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Sep. 16, 2021USD ($)
Debt Instrument [Line Items]
Advanced amount under term loan					$ 15,000,000
Interest expense				$ 2,696,000	1,906,000
Loan Agreement | Term Loan | Hercules
Debt Instrument [Line Items]
Aggregate principal amount				5,000,000		$ 75,000,000
Number of tranches | Tranche			4
Advanced amount under term loan			$ 25,000,000
Debt instrument, interest only payment end date			Nov. 1, 2022
Debt instrument repayment end date			Oct. 1, 2024
Debt instrument, end of term payment charge on funded amount percentage			5.50%
Loan carrying value		$ 15,000,000	$ 9,500,000	25,400,000	25,000,000
Loan Agreement | Term Loan | Hercules | Maximum
Debt Instrument [Line Items]
Aggregate principal amount			75,000,000
Loan Agreement | Term Loan | Hercules | Second Tranche
Debt Instrument [Line Items]
Aggregate principal amount			10,000,000
Loan Agreement | Term Loan | Hercules | First Tranche
Debt Instrument [Line Items]
Advanced amount under term loan		$ 15,000,000	10,000,000
Amount payable upon any prepayment or repayment			1,400,000
Loan Agreement | Term Loan | Hercules | Third Tranche
Debt Instrument [Line Items]
Aggregate principal amount			10,000,000
Loan Agreement | Term Loan | Hercules | Fourth Tranche
Debt Instrument [Line Items]
Aggregate principal amount			$ 30,000,000
Amended Loan Agreement | Term Loan | Hercules
Debt Instrument [Line Items]
Debt instrument, covenants, obligated to maintain account cover amount percentage			110.00%
Interest expense				$ 2,700,000	$ 1,900,000
Amended Loan Agreement | Term Loan | Hercules | Second Tranche
Debt Instrument [Line Items]
Interest rate			1.50%
Amended Loan Agreement | Term Loan | Hercules | First Tranche
Debt Instrument [Line Items]
Interest rate			2.00%
Amended Loan Agreement | Term Loan | Hercules | Third Tranche
Debt Instrument [Line Items]
Interest rate			1.00%
Amended Loan Agreement | Amended Term Loan | Hercules
Debt Instrument [Line Items]
Aggregate principal amount	$ 85,000,000
Debt instrument, interest rate terms				Advances under the Amended Term Loan Facility bear interest at a rate equal to the greater of (i) 8.25% plus the Prime Rate (as reported in The Wall Street Journal) less 3.25%, and (ii) 8.25%.
Interest rate	8.25%
Debt instrument, interest only payment end date	Oct. 1, 2023
Debt instrument, interest only payment extendable end date	Oct. 1, 2024
Debt instrument repayment end date	Oct. 1, 2025
Debt instrument, end of term payment charge on funded amount percentage	5.50%
Amended Loan Agreement | Amended Term Loan | Hercules | Prime Rate
Debt Instrument [Line Items]
Variable interest rate	8.25%
Reduced from variable interest rate	3.25%
Amended Loan Agreement | Amended Term Loan | Hercules | Third Tranche
Debt Instrument [Line Items]
Aggregate principal amount	$ 10,000,000
Amended Loan Agreement | Amended Term Loan | Hercules | Fourth Tranche
Debt Instrument [Line Items]
Aggregate principal amount	30,000,000
Amended Loan Agreement | Amended Term Loan | Hercules | Fifth Tranche
Debt Instrument [Line Items]
Debt instrument, available in minimum draws	5,000,000
Amended Loan Agreement | Amended Term Loan | Hercules | Fifth Tranche | Maximum
Debt Instrument [Line Items]
Aggregate principal amount	$ 20,000,000

Indebtedness - Schedule of Futu

Indebtedness - Schedule of Future Principal Payments (Details) - Loan Agreement $ in Thousands	Dec. 31, 2021USD ($)
Debt Instrument [Line Items]
2023	$ 2,773
2024	11,680
2025	10,547
Long-term debt	$ 25,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - $ / shares	Dec. 31, 2021	Dec. 31, 2020	Oct. 12, 2020
Class of Stock [Line Items]
Common stock, shares authorized	150,000,000	150,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Number of shares available for future issuance	6,336,842	5,832,209	834,720
2020 Stock Option and Incentive Plan
Class of Stock [Line Items]
Number of shares available for future issuance	1,573,353		1,043,402

Common Stock - Shares of Common

Common Stock - Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2021	Dec. 31, 2020	Oct. 12, 2020
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	6,336,842	5,832,209	834,720
Common Stock Reserved For Exercises Of Stock Options Issued
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	4,763,489	4,543,318
Common Stock Reserved for Future Issuances
Class of Stock [Line Items]
Shares of common stock reserved for future issuance	1,573,353	1,288,891

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	Nov. 12, 2021USD ($)Individual	Dec. 31, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares	Jan. 01, 2022shares	Oct. 12, 2020shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based awards, vesting conditions		As of December 31, 2021, the Company has granted service-based awards, which vest over a defined period of service, and performance-based and market-based awards, which vest upon the achievement of defined conditions. Service-based awards generally vest over a four-year period, with the first 25% vesting following twelve months of continued employment or service, and the remainder vesting in twelve quarterly installments over the following three years.
Share-based awards, vesting period		4 years
Shares of common stock reserved for future issuance | shares		6,336,842	5,832,209		834,720
Annual increased percentage on outstanding common stock reserved					0.50%
Number of shares available for future issuance | shares					208,680
Stock option, expiration period		10 years
Treasury stock, shares | shares		0
Weighted average grant date fair value per share of options granted | $ / shares		$ 14.33	$ 8.30
Aggregate intrinsic value of stock options exercised		$ 5,200	$ 400
Shares granted | shares		1,449,400
Stock-based compensation expense		$ 10,677	$ 7,080
Total unrecognized compensation expense related to option awards		$ 20,300
Weighted-average period of unrecognized compensation expense related to option awards		2 years 8 months 8 days
Lonza
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 500
Number of affected granted employees | Individual	12
Stock-based compensation expense recognized	$ 400
Additional compensation cost	100
Derecognition gain on assets	$ 500
Performance-Based Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares granted | shares		0	0
Stock-based compensation expense			$ 300
2020 Stock Option and Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of common stock reserved for future issuance | shares		1,573,353			1,043,402
2020 Stock Option and Incentive Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Additional shares of common stock reserved for future issuance | shares				1,119,192
2020 Stock Option and Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Annual increased percentage on outstanding common stock reserved					5.00%
Tranche 1
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based awards, vesting period		12 months
Share-based awards, vesting percentage		25.00%
Tranche 2
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Share-based awards, vesting period		3 years
Share-based awards, vesting description		twelve quarterly installments

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020
Number of Shares
Outstanding		4,543,318
Granted		1,449,400
Exercised		(433,751)
Forfeited/Cancelled		(795,478)
Outstanding		4,763,489	4,543,318
Exercisable		2,688,532
Vested and expected to vest		4,763,489
Weighted Average Exercise Price Per Share
Outstanding		$ 8.52
Granted		23.26
Exercised		8.62
Forfeited/Cancelled		11.10
Outstanding		12.56	$ 8.52
Exercisable		8.02
Vested and expected to vest		$ 12.56
Weighted Average Remaining Contractual Term
Outstanding		6 years 5 months 8 days	7 years 2 months 19 days
Exercisable		5 years 4 months 28 days
Vested and expected to vest		6 years 5 months 8 days
Outstanding	[1]	$ 10,370	$ 108,048
Exercisable	[1]	9,372
Vested and expected to vest	[1]	$ 10,370
[1]	Aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the fair value of common stock for those stock options that had exercise prices lower than the fair value of the Company’s common stock as of December 31, 2021 and 2020

Stock-Based Compensation - Su_2

Stock-Based Compensation - Summary of Assumptions used in Black-Scholes Option Pricing Model (Details) - Service-Based Awards - $ / shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	0.83%	0.68%
Expected term (in years)	6 years 2 months 12 days	6 years 2 months 4 days
Expected volatility	68.21%	68.75%
Expected dividend yield	0.00%	0.00%
Fair value per share of common stock	$ 14.37	$ 13.52

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Components and Classification of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 10,677	$ 7,080
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	4,733	3,563
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	5,409	3,517
Gain on Disposition
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	535
Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	9,862	6,547
Non-employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 815	$ 533

Collaboration Agreements - Summ

Collaboration Agreements - Summary of Total Consolidated Net Revenue from Strategic Collaborators (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Collaboration Agreements [Line Items]
Total collaboration revenue	$ 22,935	$ 2,915
Jazz
Collaboration Agreements [Line Items]
Total collaboration revenue	11,322	641
Sarepta
Collaboration Agreements [Line Items]
Total collaboration revenue	$ 11,613	$ 2,274

Collaboration Agreements - Sche

Collaboration Agreements - Schedule of Changes in Contract Assets and Liabilities (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2021USD ($)
Contract assets:
Accounts receivable, ADDITIONS	$ 3,914	[1]
Accounts receivable, DEDUCTIONS	(3,286)	[1]
Accounts receivable, BALANCE END OF PERIOD	628	[1]
Contract liabilities:
Deferred revenue, BALANCE BEGINNING OF PERIOD	62,697
Deferred revenue, DEDUCTIONS	(19,048)
Deferred revenue, BALANCE END OF PERIOD	$ 43,649
[1]	Included in prepaid expenses and other current assets as shown within the consolidated balance sheets.

Collaboration Agreements - Sc_2

Collaboration Agreements - Schedule of Revenue Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Collaboration Agreements [Abstract]
Amounts included in deferred revenue at the beginning of the period	$ 19,048	$ 641

Collaboration Agreements - Addi

Collaboration Agreements - Additional Information (Details)	Dec. 03, 2021USD ($)	Oct. 01, 2021	Jun. 30, 2021USD ($)	Jun. 17, 2020USD ($)Target	Jan. 02, 2019USD ($)CandidateTargetObligation	Apr. 30, 2021Target	Dec. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Dec. 23, 2020USD ($)
Collaboration Agreements [Line Items]
Number of performance obligations | Obligation					8
Total collaboration revenue							$ 22,935,000	$ 2,915,000
Revenue recognized was previously classified as, Deferred revenue, net of current portion							19,048,000	641,000
Deferred revenue							43,649,000
Up-front and non-refundable cash payments received							66,000,000
Deferred revenue							12,963,000	5,281,000
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited
Collaboration Agreements [Line Items]
Number of oncogene targets | Target					5
Number of targets | Target					4
Number of oncogene targets discontinue work | Target						1
Number of clinical trial candidates | Candidate					2
Number of remaining candidates | Candidate					3
Additional milestone payment related to regulatory approval of product					$ 20,000,000
Up-front payment					56,000,000
Preclinical development milestone payments eligible to receive					20,000,000
Collaboration target payment receivable due upon second initiation					10,000,000
Milestone payments eligible to receive					$ 200,000,000
Notice period for termination of agreement					180 days
Collaboration arrangement transaction price measured based on non-refundable and non creditable up-front payment							56,000,000
Variable consideration payable included in transaction price at inception							0
Remaining consideration comprised solely of transaction price									$ 55,000,000
Changes in estimate of variable consideration							0
Remaining deferred revenue recognized							10,900,000
Total collaboration revenue			$ 2,800,000				11,300,000	600,000
Deferred revenue							43,700,000	55,000,000
Deferred revenue							12,600,000
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | Research and Development
Collaboration Agreements [Line Items]
Cost associated with obligations under arrangement							2,500,000	3,300,000
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | Development and Commercialization License and Associated Research Services | ASU 2014-09
Collaboration Agreements [Line Items]
Option to include additional target additional cost					$ 0
Replacement target additional cost					0
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | Research Services | ASU 2014-09
Collaboration Agreements [Line Items]
Option to request additional research program additional cost					0
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | Non-GLP Toxicology Studies | ASU 2014-09
Collaboration Agreements [Line Items]
Per backup development candidate cost upon exercise					$ 0
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | License and Services
Collaboration Agreements [Line Items]
Performance obligation unsatisfied							39,600,000	50,900,000
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited | All Other Services
Collaboration Agreements [Line Items]
Performance obligation unsatisfied							4,100,000	4,100,000
Sarepta Research Agreement
Collaboration Agreements [Line Items]
Up-front payment				$ 7,000,000
Milestone payments eligible to receive				$ 192,500,000
Total collaboration revenue	$ 7,000,000						11,600,000	2,300,000
Revenue recognized was previously classified as, Deferred revenue, net of current portion	$ 7,000,000
Deferred revenue							0	7,700,000
Research agreement period		2 years		2 years
Number of agreed targets | Target				5
Effective contract termination date		Dec. 3, 2021
Term of option exercise				Jun. 17, 2022
Extended term of option exercise				Dec. 17, 2022
Up-front and non-refundable cash payments received				$ 10,000,000
Up-front research services prepayment				3,000,000
Collaboration arrangement obligated to remit option exercise payment				12,500,000
Collaboration arrangement obligated options exercised				62,500,000
Sarepta Research Agreement | Research and Development
Collaboration Agreements [Line Items]
Cost associated with obligations under arrangement							$ 4,600,000	2,300,000
Sarepta Research Agreement | ASU 2014-09
Collaboration Agreements [Line Items]
Up-front payment				7,000,000
Up-front research services prepayment				3,000,000
Aggregate transaction price				18,000,000
Estimation of cost reimbursements				$ 8,000,000
Sarepta Research Agreement | All Other Services
Collaboration Agreements [Line Items]
Performance obligation unsatisfied								7,000,000
Sarepta Research Agreement | Research License and Services
Collaboration Agreements [Line Items]
Performance obligation unsatisfied								$ 8,700,000

Collaboration Agreements - Sc_3

Collaboration Agreements - Schedule of Transaction Price Allocated to Identified Performance Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Jun. 17, 2020
Collaboration and License Agreement | Jazz Pharmaceuticals Ireland Limited
Collaboration Agreements [Line Items]
License and Services Performance Obligation: Initial Collaboration Target #1	$ 12,717
License and Services Performance Obligation: Initial Collaboration Target #2	13,702
License and Services Performance Obligation: Initial Collaboration Target #3	10,866
License and Services Performance Obligation: Initial Collaboration Target #4	13,593
Additional Target or Program Material Right Performance Obligation	2,812
Replacement Target Material Right Performance Obligation	1,188
Backup Candidate Material Right Performance Obligation: Backup Candidate #1	47
Backup Candidate Material Right Performance Obligation: Backup Candidate #2	47
Transaction Price	$ 54,972
Sarepta Research Agreement
Collaboration Agreements [Line Items]
Transaction Price		$ 18,000
Research License and Services Performance Obligation		11,000
Material Right Performance Obligation: Research Target #1		1,400
Material Right Performance Obligation: Research Target #2		1,400
Material Right Performance Obligation: Research Target #3		1,400
Material Right Performance Obligation: Research Target #4		1,400
Material Right Performance Obligation: Research Target #5		$ 1,400

Other Significant Agreements -

Other Significant Agreements - Additional Information (Details)	Feb. 17, 2021shares	Oct. 16, 2020shares	Nov. 06, 2018USD ($)shares	Jan. 31, 2020USD ($)shares	Nov. 30, 2015USD ($)shares	Dec. 31, 2021USD ($)Milestoneshares	Dec. 31, 2020USD ($)shares	Dec. 31, 2018USD ($)	Feb. 01, 2021USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development						$ 64,855,000	$ 73,981,000
Stock issued, new issues | shares	3,162,500	5,500,000
Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Stock issued, new issues | shares						3,162,500	5,500,000
MD Anderson Cancer Center | Patent and Technology License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Remaining funding amount for patent-related costs under license agreement						$ 0
Number of days of prior written notice to terminate agreement						180 days
Number of milestones achieved | Milestone						0
Payments with respect to license agreement						$ 0	$ 0
MD Anderson Cancer Center | Patent and Technology License Agreement | Minimum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Patent costs									$ 1,500,000
MD Anderson Cancer Center | Patent and Technology License Agreement | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent future payments upon achievement of certain development and regulatory approval milestones					$ 11,900,000
Contingent payments in cash or through issuance of equity					4,400,000
MD Anderson Cancer Center | Patent and Technology License Agreement | Maximum | Diagnostic Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent future payments upon achievement of certain development and regulatory approval milestones					2,400,000
MD Anderson Cancer Center | Patent and Technology License Agreement | Maximum | Therapeutic Products
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Contingent future payments upon achievement of certain development and regulatory approval milestones					9,500,000
MD Anderson Cancer Center | Research Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research agreement extension of expiration year and month						2021-02
Research and development expense payment due year one					1,000,000
Research and development expense payment due year two through five					$ 1,250,000
Percentage of overhead charges on direct expenses					25.00%
Preferred stock shares issuable in year one under research agreement | shares					200,000
Preferred stock shares issuable in year two through five under research agreement | shares					20,833
Research agreement expiration date					Dec. 31, 2019
Research and development				$ 1,200,000
Research and development expense payment due					$ 0
Preferred stock shares issuable under research agreement | shares					0
MD Anderson Cancer Center | Research Agreement | Series B Redeemable Convertible Preferred Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Stock issued, new issues | shares				62,500
Expense recognized to estimate fair value of shares						$ 0	0
Kayla Therapeutics S.A.S | Kayla License Agreement
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of days of prior written notice to terminate agreement						30 days
Payments with respect to license agreement						$ 0
Upfront payment paid in cash			$ 6,500,000
Acquired in-process research and development expense								$ 8,100,000
Cash payment related to acquired in-process research and development								6,500,000
Royalty term determination period after first commercial sale of such product in such country						10 years
Number of days of notice to terminate agreement upon material breach						60 days
Kayla Therapeutics S.A.S | Kayla License Agreement | Phase 1/2 Clinical Trial
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Number of milestones achieved | Milestone						0
Non-refundable milestone payment in cash			$ 15,000,000
Non-refundable milestone payment in common stock | shares			177,318
Milestone payment							$ 15,000,000
Kayla Therapeutics S.A.S | Kayla License Agreement | Common Stock
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Shares issued in consideration for license agreement | shares			118,212
Value of shares issued, acquired in process research and development								$ 1,600,000
Kayla Therapeutics S.A.S | Kayla License Agreement | Maximum | Phase 1/2 Clinical Trial
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Obligated to make cash payments upon achievement of clinical and regulatory milestones			$ 100,000,000
Value of common stock shares payable upon achievement of clinical and regulatory milestones			$ 13,000,000

401(k) Plan - Additional Inform

401(k) Plan - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Retirement Benefits [Abstract]
Defined contribution plan, employer matching contribution, percent of match	50.00%
Defined contribution plan, maximum annual contributions per employee, percent	6.00%
Defined contribution expense	$ 0.6	$ 0.4

Net Loss Per Share - Basic and

Net Loss Per Share - Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Numerator:
Net loss	$ (37,157)	$ (91,665)
Cumulative dividends on redeemable convertible preferred stock		(10,831)
Net loss attributable to common stockholders	$ (37,157)	$ (102,496)
Denominator:
Weighted average common shares outstanding, basic and diluted	21,794,546	6,332,841
Net loss per share attributable to common stockholders, basic and diluted	$ (1.70)	$ (16.18)

Net Loss Per Share - Additional

Net Loss Per Share - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Outstanding Stock Options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net loss per share attributable to common stockholders	4,763,489	4,543,318

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Taxes [Line Items]
Income tax benefits for net operating losses	$ 0	$ 0
Changes in valuation allowance for deferred tax assets	12,300,000	27,500,000
Unrecognized tax benefits	$ 0	0
Operating loss carryforwards, limitations on use	Net operating loss carryforwards may become subject to an annual limitation in the event of certain cumulative changes in the ownership interest of significant shareholders over a three-year period in excess of 50%, as defined under Sections 382 and 383 of the Internal Revenue Code, respectively, as well as similar state provisions.
Accrued interest related to uncertain tax positions	$ 0	0
Accrued penalties related to uncertain tax positions	0	0
Interest amounts recognized	0	0
Penalty amounts recognized	0	$ 0
Domestic Tax Authority
Income Taxes [Line Items]
Net operating loss carryforwards	189,400,000
Deferred tax assets, operating loss carryforwards, not subject to expiration	152,900,000
Deferred tax assets, operating loss carryforwards, subject to expiration	36,400,000
Domestic Tax Authority | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforward	$ 10,500,000
Tax credit carryforward, expiration year	2035
State
Income Taxes [Line Items]
Net operating loss carryforwards	$ 188,700,000
Operating loss carryforwards, expiration year	2035
State | Research Tax Credit Carryforward
Income Taxes [Line Items]
Tax credit carryforward	$ 5,000,000
Tax credit carryforward, expiration year	2031

Income Taxes - Summary of Recon

Income Taxes - Summary of Reconciliation of US Statutory Income Tax Rate to the Company's Effective Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
Federal statutory income tax rate%	21.00%	21.00%
State taxes, net of federal benefit	8.50%	7.40%
Federal and state research and development credits	5.90%	2.70%
Executive Compensation	(0.70%)	(0.30%)
Non-deductible items	(0.10%)	(0.10%)
Stock Compensation	(1.50%)	(0.80%)
Change in valuation allowance	(33.20%)	(30.00%)
Other	0.10%	0.10%

Income Taxes - Summary of Signi

Income Taxes - Summary of Significant Components of Company's Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Net operating loss carryforwards	$ 51,672	$ 37,609
Capitalized license and research and development payments	7,786	8,393
Research and development credits	15,062	11,910
Deferred revenue	11,919	17,117
Lease liabilities	10,105	10,519
Accrued bonus	1,085	1,053
Stock compensation	4,344	3,335
Other temporary differences	289	349
Total deferred tax assets	102,262	90,285
Valuation allowance	(93,091)	(80,758)
Deferred tax assets	9,171	9,527
Deferred tax liabilities:
Right-of-use asset	(5,996)	(6,007)
Depreciation	$ (3,175)	$ (3,520)