0001558370-23-002992 | 10-K | XBRL Viewer | Scholar Rock Holding Corp

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2022	Mar. 02, 2023	Jun. 30, 2022
Document and Entity Information
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2022
Document Transition Report	false
Entity File Number	001-38501
Entity Registrant Name	SCHOLAR ROCK HOLDING CORP
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-3750435
Entity Address, Address Line One	301 Binney Street, 3rd Floor
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	857
Local Phone Number	259-3860
Title of 12(b) Security	Common Stock
Trading Symbol	SRRK
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
ICFR Auditor Attestation Flag	false
Entity Shell Company	false
Entity Public Float			$ 109.5
Entity Common Stock, Shares Outstanding		51,985,072
Auditor Name	Ernst & Young LLP
Auditor Firm ID	42
Auditor Location	Boston, Massachusetts
Entity Central Index Key	0001727196
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	FY
Amendment Flag	false

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 103,275	$ 212,835
Marketable securities	212,086	40,159
Prepaid expenses and other current assets	12,663	12,325
Total current assets	328,024	265,319
Property and equipment, net	7,384	9,564
Operating lease right-of-use asset	18,543	25,442
Restricted cash	2,498	2,498
Other long-term assets	1,719	1,622
Total assets	358,168	304,445
Current liabilities:
Accounts payable	3,994	4,434
Accrued expenses	24,321	17,456
Operating lease liability	7,852	7,407
Short-term debt		1,577
Deferred revenue		33,193
Other current liabilities	222	230
Total current liabilities	36,389	64,297
Long-term portion of operating lease liability	11,800	19,652
Long-term debt	49,744	48,422
Total liabilities	97,933	132,371
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.001 par value; 10,000,000 shares authorized at December 31, 2022 and December 31, 2021; no shares issued and outstanding at December 31, 2022 and December 31, 2021
Common stock, $0.001 par value; 150,000,000 shares authorized; 51,672,579 and 35,209,099 shares issued and outstanding as of December 31, 2022 and December 31, 2021, respectively	52	35
Additional paid-in capital	771,699	548,204
Accumulated other comprehensive loss	(884)	(35)
Accumulated deficit	(510,632)	(376,130)
Total stockholders' equity	260,235	172,074
Total liabilities and stockholders' equity	$ 358,168	$ 304,445

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	51,672,579	35,209,099
Common stock, shares outstanding	51,672,579	35,209,099

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS
Revenue	$ 33,193	$ 18,816
Operating expenses:
Research and development	124,444	108,468
General and administrative	43,119	40,269
Total operating expenses	167,563	148,737
Loss from operations	(134,370)	(129,921)
Other income (expense), net	(132)	(1,878)
Net loss	$ (134,502)	$ (131,799)
Net loss per share, basic (in dollars per share)	$ (2.26)	$ (3.59)
Net loss per share, diluted (in dollars per share)	$ (2.26)	$ (3.59)
Weighted average common shares outstanding, basic (in shares)	59,611,656	36,711,833
Weighted average common shares outstanding, diluted (in shares)	59,611,656	36,711,833
Comprehensive loss:
Net loss	$ (134,502)	$ (131,799)
Other comprehensive loss:
Unrealized loss on marketable securities	(849)	(33)
Total other comprehensive loss	(849)	(33)
Comprehensive loss	$ (135,351)	$ (131,832)

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Total
Balance at beginning at Dec. 31, 2020	$ 34	$ 505,069	$ (2)	$ (244,331)	$ 260,770
Balance at beginning (in shares) at Dec. 31, 2020	34,152,470
Increase (decrease) in Stockholders' Equity
Unrealized loss on marketable securities			(33)		(33)
Exercise of stock options	$ 1	6,891			6,892
Exercise of stock options (in shares)	556,629
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs		13,095			13,095
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs (in shares)	500,000
Equity-based compensation expense		23,149			23,149
Net Loss				(131,799)	(131,799)
Balance at end at Dec. 31, 2021	$ 35	548,204	(35)	(376,130)	172,074
Balance at end (in shares) at Dec. 31, 2021	35,209,099
Increase (decrease) in Stockholders' Equity
Unrealized loss on marketable securities			(849)		(849)
Exercise of stock options	$ 1	495			496
Exercise of stock options (in shares)	44,850
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs	$ 16	195,299			195,315
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs (in shares)	16,326,530
Issuance of common shares upon RSU vesting (in shares)	92,100
Equity-based compensation expense		27,701			27,701
Net Loss				(134,502)	(134,502)
Balance at end at Dec. 31, 2022	$ 52	$ 771,699	$ (884)	$ (510,632)	$ 260,235
Balance at end (in shares) at Dec. 31, 2022	51,672,579

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (134,502)	$ (131,799)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,986	2,627
Amortization of debt discount and debt issuance costs	720	335
Loss on disposal of property and equipment	33	24
Equity-based compensation	27,701	23,149
Amortization/accretion of investment securities	(2,142)	918
Non-cash operating lease expense	6,899	6,397
Change in operating assets and liabilities:
Prepaid expenses and other current assets	(322)	(8,530)
Other assets	(97)	(601)
Accounts payable	(251)	1,016
Accrued expenses	6,889	3,663
Operating lease liabilities	(7,407)	(5,400)
Deferred revenue	(33,193)	(18,816)
Other liabilities	(8)	228
Net cash used in operating activities	(132,694)	(126,789)
Cash flows from investing activities:
Purchases of property and equipment	(1,064)	(5,248)
Purchases of marketable securities	(300,634)	(60,437)
Maturities of marketable securities	130,000	200,000
Net cash (used in) provided by investing activities	(171,698)	134,315
Cash flows from financing activities:
Proceeds from debt		24,984
Proceeds from sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs	195,315	13,095
Debt modification payment	(975)
Proceeds from stock option exercises	492	6,892
Other		(20)
Net cash provided by financing activities	194,832	44,951
Net (decrease) increase in cash, cash equivalents and restricted cash	(109,560)	52,477
Cash, cash equivalents and restricted cash, beginning of period	215,333	162,856
Cash, cash equivalents and restricted cash, end of period	105,773	215,333
Supplemental disclosure of non-cash items:
Property and equipment purchases in accounts payable and accrued expenses		212
Supplemental cash flow information:
Cash paid for interest	$ 4,372	$ 2,082

Nature of the Business and Basis of Presentation

12 Months Ended

Dec. 31, 2022

Nature of the Business and Basis of Presentation

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Organization

Scholar Rock Holding Corporation (the “Company”) is a biopharmaceutical company focused on the discovery and development of innovative medicines for the treatment of serious diseases in which signaling by protein growth factors plays a fundamental role. As a global leader in transforming growth factor beta (“TGFβ”) superfamily biology, the Company’s novel understanding of the molecular mechanisms of growth factor activation enabled the development of a proprietary platform for the discovery and development of monoclonal antibodies that locally and selectively target the precursor, or latent, forms of growth factors. The Company’s first product candidate, apitegromab, is a highly selective, fully human, monoclonal antibody, with a unique mechanism of action that results in inhibition of the activation of the growth factor, myostatin, in skeletal muscle. Apitegromab is being developed as a potential first muscle-targeted therapy for the treatment of spinal muscular atrophy (“SMA”). The Company is conducting SAPPHIRE, a pivotal Phase 3 clinical trial to evaluate the efficacy and safety of apitegromab in patients with nonambulatory Type 2 and Type 3 SMA. In June 2022, the Company announced 24-month efficacy and safety extension data of apitegromab in patients with Type 2 and Type 3 SMA from the Phase 2 TOPAZ proof-of-concept clinical trial. The Company’s second product candidate, SRK-181, is being developed for the treatment of cancers that are resistant to checkpoint inhibitor (“CPI”) therapies, such as anti-PD-1 or anti-PD-L1 antibody therapies. SRK-181 is a highly selective inhibitor of the activation of latent transforming growth factor beta-1 (“TGFβ1”) that is being investigated in the Company’s Phase 1 DRAGON proof-of-concept clinical trial in patients with locally advanced or metastatic solid tumors that exhibit resistance to anti-PD-(L)1 antibodies. The DRAGON trial consists of two parts: Part A (dose escalation of SRK-181 as a single-agent or in combination with an approved anti-PD-(L)1 therapy) and Part B (dose expansion evaluating SRK-181 in combination with an approved anti-PD- (L)1 antibody therapy). Part B includes the following active cohorts: urothelial carcinoma, cutaneous melanoma, non-small cell lung cancer, clear cell renal cell carcinoma and head and neck squamous cell carcinoma. Additionally, the Company continues to create a pipeline of product candidates to deliver novel therapies to underserved patients suffering from a wide range of serious diseases, including neuromuscular disorders, cancer, fibrosis, and iron-restricted anemia. The Company was originally formed in May 2012. Its principal offices are in Cambridge, Massachusetts.

Since its inception, the Company’s operations have focused on research and development of monoclonal antibodies that selectively inhibit activation of growth factors for therapeutic effect, as well as establishing the Company’s intellectual property portfolio and performing research and development activities. The Company has primarily financed its operations through various equity financings (Note 8), as well as research and development collaboration agreements and the Company’s debt facility (Note 12).

Revenue generation activities have been limited to two collaborations, both containing research services and the issuance of a license. The first agreement, executed in 2013, was with Janssen Biotech, Inc. (“Janssen”), a subsidiary of Johnson & Johnson and was terminated in July 2022. The second agreement, the Gilead Collaboration Agreement with Gilead Sciences, Inc. (“Gilead”), was in effect between December 2018 and January 2022. No revenues have been recorded from the sale of any commercial product.

The Company is subject to a number of risks similar to other life science companies, including, but not limited to, successful discovery and development of its drug candidates, raising additional capital, development by its competitors of new technological innovations, protection of proprietary technology and regulatory approval and market acceptance of the Company’s product candidates. The Company anticipates that it will continue to incur significant operating losses for the next several years as it continues to develop its product candidates. The Company believes that its existing cash, cash equivalents, and marketable securities at December 31, 2022 will be sufficient to allow the Company to fund its current operations through at least a period of one year after the date these financial statements are issued.

Basis of Presentation

The consolidated financial statements include the accounts of Scholar Rock Holding Corporation and its wholly owned subsidiaries. All intercompany balances have been eliminated in consolidation.

These consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the U.S. (“GAAP”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”).

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of financial statements in accordance with GAAP requires management to make estimates and judgments that may affect the reported amounts of assets and liabilities and related disclosures of contingent assets and liabilities at the date of the financial statements and the related reporting of revenues and expenses during the reporting period. Management bases its estimates on historical experience and on various assumptions that are believed to be reasonable under the circumstances. Actual results could differ from those estimates.

Concentration of Credit Risk and Off-Balance Sheet Risk

The Company has no off-balance sheet risk, such as foreign exchange contracts, option contracts or other foreign-hedging arrangements. The Company follows an investment policy approved by the Board of Directors. Its primary objectives are the preservation of capital and maintenance of liquidity. The Company invests only in fixed income instruments denominated and payable in U.S. dollars including obligations of the U.S. government and its agencies and money market funds registered according to SEC Rule 2a-7 of the Investment Company Act of 1940. All securities must have a readily ascertainable market value, must be readily marketable and be U.S. dollar denominated.

Cash, Cash Equivalents and Restricted Cash

The Company considers highly liquid investments with a maturity of three months or less when purchased to be cash equivalents. Cash equivalents are stated at cost, which approximates market value. At December 31, 2022 and 2021, cash equivalents include money market funds that invest primarily in U.S. government-backed securities and treasuries.

At December 31, 2022 and 2021, restricted cash consists of letters of credit in the amount of $2.5 million related to its leased facilities. The following table reconciles cash, cash equivalents and restricted cash per the balance sheet to the statement of cash flows (in thousands):


	As of December 31,
	2022		2021
Cash and cash equivalents	$	103,275	$	212,835
Restricted cash		2,498		2,498
	$	105,773	$	215,333

Marketable Securities

The Company classifies its marketable securities as available-for-sale. Marketable securities with a remaining maturity date greater than one year are classified as non-current. Marketable securities are maintained by an investment manager and consist of U.S. treasury securities. Marketable securities are carried at fair value with the unrealized gains and losses included in accumulated other comprehensive loss as a component of stockholders’ equity until realized. Any premium or discount arising at purchase is amortized and/or accreted to interest income and/or expense over the life of the underlying marketable security.

Although available to be sold to meet operating needs or otherwise, securities are generally held through maturity. The cost of securities sold is determined on a specific identification basis, and realized gains and losses are included in other income (expense) within the statement of operations and comprehensive loss. During the years ended December 31, 2022 and 2021, no marketable securities were adjusted for other than temporary declines in fair value.

The Company evaluates its marketable securities with unrealized losses for other-than-temporary impairment. When assessing marketable securities for other-than-temporary declines in value, the Company considers such factors as, among other things, how significant the decline in value is as a percentage of the original cost, how long the market value of the investment has been less than its original cost, the Company’s ability and intent to retain the investment for a period of time sufficient to allow for any anticipated recovery in fair value and market conditions in general. 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 would reduce the investment to fair value through a charge to the statement of operations and comprehensive loss. No such adjustments were necessary during the periods presented.

Property and Equipment

Property and equipment are recorded at cost. Expenditures for major renewals or betterments that extend the useful lives of property and equipment are capitalized; expenditures for maintenance and repairs are charged to expense as incurred. Depreciation is calculated on a straight-line basis over the estimated useful lives of the related asset. Property and equipment are depreciated as follows:


		Estimated Useful Life
		(in Years)
Laboratory equipment		3 – 5
Computer equipment & software		3
Furniture & fixtures		5
Machinery & equipment		3 – 5
Leasehold improvements		Shorter of the useful life or remaining lease term

Impairment of Long-Lived Assets

Long-lived assets consist of property and equipment and right-of-use assets. Long-lived assets to be held and used are tested for recoverability whenever events or changes in business circumstances indicate that the carrying amount of the assets may not be fully recoverable. Factors that the Company considers in deciding when to perform an impairment review include significant underperformance of the business in relation to expectations, significant negative industry or economic trends and significant changes or planned changes in the use of the assets. If an impairment review is performed to evaluate a long-lived asset group for recoverability, the Company compares forecasts of undiscounted cash flows expected to result from the use and eventual disposition of the long-lived asset group to its carrying value. An impairment loss would be recognized when estimated undiscounted future cash flows expected to result from the use of an asset group are less than its carrying amount. The impairment loss would be based on the excess of the carrying value of the impaired asset group over its fair value, determined based on discounted cash flows. The Company did not record any impairment losses on long-lived assets during the years ended December 31, 2022 or 2021.

Leases

The Company accounts for leases using ASC Topic 842, Leases (“ASC 842”). At the inception of an arrangement, the Company determines whether the arrangement is or contains a lease based on the unique facts and circumstances present. Leases with a term greater than one year are recognized on the balance sheet as right-of-use assets, lease liabilities and, if applicable, long-term lease liabilities. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected remaining lease term. Certain adjustments to the right-of-use asset may be required for items such as incentives received. The interest rate implicit in lease contracts is typically not readily determinable. As a result, the Company utilizes its estimated incremental borrowing rates, which are the rates incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment.

In accordance with the guidance in ASC 842, components of a lease should be split into three categories: lease components (e.g. land, building, etc.), non-lease components (e.g. common area maintenance, consumables, etc.), and non-components (e.g. property taxes, insurance, etc.). Then the fixed and in-substance fixed contract consideration (including any related to non-components) must be allocated based on the respective relative fair values to the lease components and non-lease components. For operating leases, lease expense relating to fixed payments is recognized on a straight-line basis over the term and lease expense relating to variable payments is expensed as incurred.

Fair Value Measurements

ASC Topic 820, Fair Value Measurement ("ASC 820"), establishes a fair value hierarchy for instruments measured at fair value that distinguishes between assumptions based on market data (observable inputs) and the Company’s own assumptions (unobservable inputs). 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. ASC 820 identifies fair value as the exchange price, or exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As a basis for considering market participant assumptions in fair value measurements, ASC 820 establishes a three-tier fair value hierarchy that distinguishes between the following:

Level 1 — Quoted market prices in active markets for identical assets or liabilities.

Level 2 — Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves.

Level 3 — Unobservable inputs developed using estimates of assumptions developed by the Company, which reflect those that a market participant would use.

To the extent the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair values requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized as Level 3. 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.

Segment Information

Operating segments are defined as components of an entity about which separate discrete information is available for evaluation by the chief operating decision maker, or decision-making group, in deciding how to allocate resources and in assessing performance. The Company views its operations and manages its business in one operating segment operating exclusively in the U.S.

Revenue Recognition

The Company accounts for revenue using the provisions of ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). Under ASC 606, an entity recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration which the entity expects to receive in exchange for those goods or services. To determine the appropriate amount of revenue to be recognized for arrangements determined to be within the scope of ASC 606, the Company performs the following five steps: (i) identification of the contract(s) with the customer, (ii) identification of the promised goods or services in the contract and determination of whether the promised goods or services are performance obligations, (iii) measurement of the transaction price, (iv) allocation of the transaction price to the performance obligations, and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. The Company only applies the five-step model to contracts when it is probable that the entity will collect consideration it is entitled to in exchange for the goods or services it transfers to the customer. At contract inception, once the contract is determined to be within the scope of ASC 606, the Company assesses the goods or services promised within each contract and determines those that are performance obligations, and assesses whether each promised good or service is distinct. The Company then recognizes as revenue the amount of the transaction price that is allocated to the respective performance obligation when (or as) the performance obligation is satisfied.

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 or services to be transferred can be identified, (iii) the payment terms for the goods 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 or services that will be transferred to the customer is probable.

The Company first evaluates license and/or collaboration arrangements to determine whether the arrangement (or part of the arrangement) represents a collaborative arrangement pursuant to ASC Topic 808, Collaborative Arrangements, based on the risks and rewards and activities of the parties pursuant to the contractual arrangement. The Company accounts for collaborative arrangements (or elements within the contract that are deemed part of a collaborative arrangement), which represent a collaborative relationship and not a customer relationship, outside of the scope of ASC 606. The Company’s two collaborations represented revenue arrangements.

For the arrangements or arrangement components that are subject to revenue accounting guidance, in determining the appropriate amount of revenue to be recognized as it fulfills its obligations under each of its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation. As part of the accounting for these arrangements, the Company must use significant judgment to determine: a) the number of performance obligations based on the determination under step (ii) above and whether those performance obligations are distinct from other performance obligations in the contract; b) the transaction price under step (iii) above; and c) the standalone selling price for each performance obligation identified in the contract for the allocation of transaction price in step (iv) above. The Company uses judgment to determine whether milestones or other variable consideration, except for royalties, should be included in the transaction price as described further below. The transaction price is allocated to each performance obligation on a relative stand-alone selling price basis, for which the Company recognizes revenue as or when the performance obligations under the contract are satisfied. In determining the stand-alone selling price of a license to the Company’s proprietary technology or a material right provided by a customer option, the Company considers market conditions as well as entity-specific factors, including those factors contemplated in negotiating the agreements as well as internally developed estimates that include assumptions related to the market opportunity, estimated development costs, probability of success and the time needed to commercialize a product candidate pursuant to the license. In validating its estimated stand-alone selling prices, the Company evaluates whether changes in the key assumptions used to determine its estimated stand-alone selling prices will have a significant effect on the allocation of arrangement consideration between performance obligations.

The Company estimates the transaction price based on the amount of consideration the Company expects to be received for transferring the promised goods or services in the contract. The consideration may include both fixed consideration and variable consideration. At the inception of each arrangement that includes variable consideration, the Company evaluates the amount of the potential payments and the likelihood that the payments will be received. The Company utilizes either the most likely amount method or expected value method to estimate the transaction price based on which method better predicts the amount of consideration expected to be received. If it is probable that a significant revenue reversal would not occur, the variable consideration is included in the transaction price.

Performance obligations are promised goods or services in a contract to transfer a distinct good or service to the customer. Promised goods or services are considered distinct when: (i) the customer can benefit from the good or service on its own or together with other readily available resources and (ii) the promised good or service is separately identifiable from other promises in the contract. In assessing whether promised goods or services are distinct, the Company considers factors such as the stage of development of the underlying intellectual property, the capabilities of the customer to develop the intellectual property on their own and whether the required expertise is readily available.

The Company allocates the transaction price based on the estimated standalone selling price. The Company must develop assumptions that require judgment to determine the standalone selling price for each performance obligation

identified in the contract. The Company utilizes key assumptions to determine the standalone selling price, which may include other comparable transactions, pricing considered in negotiating the transaction and the estimated costs. Estimating costs for research and development programs is subjective as the Company estimates the costs anticipated to successfully complete the research performance obligations. As the research is novel, efforts to be successful may be significantly different than the estimated costs at the beginning of the contract. Certain variable consideration is allocated specifically to one or more performance obligations in a contract when the terms of the variable consideration relate to the satisfaction of the performance obligation and the resulting amounts allocated to each performance obligation are consistent with the amounts the Company would expect to receive for each performance obligation.

For performance obligations which consist of licenses and other promises, the Company utilizes judgment to assess the nature of the combined performance obligation in order to determine whether the combined performance obligation is satisfied over time or at a point in time. The Company determines the appropriate method of measuring progress of combined performance obligations satisfied over time 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. The estimated remaining costs is highly subjective, as the research is novel, therefore efforts to be successful may be significantly different than the estimated costs made at the balance sheet date. If the license to the Company’s intellectual property is determined to be distinct from the other performance obligations identified in the arrangement, the Company will recognize revenue from non-refundable, up-front fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. The Company receives payments from customers based on billing schedules established in each contract. Up-front payments and fees are recorded as deferred revenue upon receipt or when due until the Company performs its obligations under these arrangements. Amounts expected to be recognized as revenue within the 12 months following the balance sheet date are classified as the current portion of deferred revenue in the accompanying consolidated balance sheets. Amounts not expected to be recognized as revenue within the 12 months following the balance sheet date are classified as deferred revenue, net of current portion. Amounts are recorded as accounts receivable when the Company’s right to consideration is unconditional. Amounts recognized as revenue, but not yet received or invoiced, are generally recognized as contract assets.

Exclusive Licenses – If the license granted in the arrangement is determined to be distinct from the other promises or performance obligations identified in the arrangement, which generally include research and development services, the Company recognizes revenue from non-refundable, upfront fees allocated to the license when the license is transferred to the customer and the customer is able to use and benefit from the license. In assessing whether a license is distinct from the other promises, the Company considers relevant facts and circumstances of each arrangement, including the research and development capabilities of the collaboration partner and the availability of the associated expertise in the general marketplace. In addition, the Company considers whether the collaboration partner can benefit from the license for its intended purpose without the receipt of the remaining promise, whether the value of the license is dependent on the unsatisfied promise, whether there are other vendors that could provide the remaining promise, and whether it is separately identifiable from the remaining promise. For licenses that are combined with other promises, the Company utilizes judgment to assess the nature of the combined performance obligation to determine whether the combined performance obligation is satisfied over time or at a point in time and, if over time, the appropriate method of measuring progress for purposes of recognizing revenue. The Company evaluates the measure of progress each reporting period and, if necessary, adjusts the measure of performance and related revenue recognition. The measure of progress, and thereby periods over which revenue should be recognized, are subject to estimates by management and may change over the course of the arrangement.

Research and Development Services – The promises under the Company’s collaboration and license agreements generally include research and development services to be performed by the Company on behalf of the collaboration partner. For performance obligations that include research and development services, the Company generally recognizes revenue allocated to such performance obligations based on an appropriate measure of progress. The Company utilizes judgment to determine the appropriate method of measuring progress for purposes of recognizing revenue, which is generally an input measure, such as costs incurred. The Company evaluates the measure of progress each reporting period as described under Exclusive Licenses above. Reimbursements from the partner that are the result of a collaborative relationship with the partner, instead of a customer relationship, such as co-development activities, are generally recorded as a reduction to research and development expense.

Customer Options – The Company’s arrangements may provide a collaborator with the right to certain optional purchases, such as the right to license a target either at the inception of the arrangement or within a pre-defined option period. Under these agreements, fees may be due to the Company (i) at the inception of the arrangement as an upfront fee or payment or (ii) upon the exercise of an option to acquire a license. If an arrangement is determined to contain customer options that allow the customer to acquire additional goods or services, the goods and services underlying the customer options are not considered to be performance obligations at the outset of the arrangement, as they are contingent upon option exercise. The Company evaluates the customer options for material rights, or options to acquire additional goods or services for free or at a discount. If the customer options are determined to represent a material right, the material right is recognized as a separate performance obligation at the inception of the arrangement. The Company allocates the transaction price to material rights based on the relative stand-alone selling price, which is determined based on the identified discount, and the probability that the customer will exercise the option. Amounts allocated to a material right are not recognized as revenue until, at the earliest, the option is exercised or expires.

Milestone Payments – At the inception of each arrangement that includes milestone payments based on certain events, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the associated milestone value is included in the transaction price. Milestone payments that are not within the control of the Company or the licensee, such as regulatory approvals, are not considered probable of being achieved until those approvals are received. The Company evaluates factors such as the scientific, clinical, regulatory, commercial, and other risks that must be overcome to achieve the particular milestone in making this assessment. There is considerable judgment involved in determining whether it is probable that a significant revenue reversal would not occur. At the end of each subsequent reporting period, the Company reevaluates the probability of achievement of all milestones subject to constraint and, if necessary, adjusts its estimate of the overall transaction price. Any such adjustments are recorded on a cumulative catch-up basis, which would affect revenues and earnings in the period of adjustment. If a milestone or other variable consideration relates specifically to the Company’s efforts to satisfy a single performance obligation or to a specific outcome from satisfying the performance obligation, the Company generally allocates the milestone amount entirely to that performance obligation once it is probable that a significant revenue reversal would not occur.

Royalties – For arrangements that include sales-based royalties, including milestone payments based on a level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (i) when the related sales occur or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied). To date, the Company has not recognized any royalty revenue resulting from any of its licensing arrangements.

For a complete discussion of accounting for collaboration revenues, see Note 13, Agreements.

Research and Development Expenses and Accruals

Research and development expenses are expensed as incurred and consist of costs incurred in performing research and development activities, including compensation related expenses for research and development personnel, preclinical and clinical activities including cost of drug supply, overhead expenses including facilities expenses, materials and supplies, amounts paid to consultants and outside service providers, and depreciation of equipment. Upfront license payments related to acquired technologies which have not yet reached technological feasibility and have no alternative future use are also included in research and development expense.

The Company has entered into various research and development service arrangements under which vendors perform various services. The Company records accrued expenses for estimated costs incurred under the arrangements. When evaluating the adequacy of the accrued expenses, the Company analyzed the progress of the studies, trials or other services performed, including invoices received and contracted costs. Significant judgments and estimates are made in determining the accrued expense balances at the end of each reporting period.

Equity-Based Compensation

The Company accounts for equity awards, including restricted stock awards, restricted stock units, and common stock options, granted as equity award compensation in accordance with ASC Topic 718, Compensation — Stock Compensation ("ASC 718"). ASC 718 requires all stock-based payments to employees, which includes grants of employee equity awards, to be recognized as expense in the statements of operations based on their grant date fair values.

The fair value of each restricted stock award and restricted stock unit is based on the fair value of the Company’s common stock less any purchase price, if applicable. The fair value of each stock option award is estimated using the Black-Scholes option-pricing model, which uses as inputs the fair value of the Company’s common stock and certain subjective assumptions, including the expected stock price volatility, the expected term of the award, the risk-free rate, and expected dividends. Expected volatility is calculated based on reported volatility data for a representative group of publicly traded companies for which historical information was available. The historical volatility is generally calculated based on a period of time commensurate with the expected term assumptions. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected term assumption. The Company uses the simplified method, under which the expected term is presumed to be the midpoint between the vesting date and the end of the contractual term. The Company utilizes this method due to lack of historical exercise data and the plain nature of its stock-based awards. The expected dividend yield is assumed to be zero as the Company has never paid dividends and has no current plans to pay any dividends on common stock.

Compensation expense related to equity awards to employees that are subject to graded vesting is recognized on a straight-line basis, based on the grant date fair value, over the requisite service period of the award, which is generally the vesting term. For awards subject to performance conditions, the Company recognizes equity award compensation expense using an accelerated recognition method over the remaining service period when management determines that achievement of the milestone is probable. Management evaluates when the achievement of a performance-based milestone is probable based on the relative satisfaction of the performance conditions as of the reporting date.

The Company classifies equity-based compensation expense in its consolidated statements 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 accounts for forfeitures when they occur.

Comprehensive Loss

Comprehensive loss is the change in equity of a business enterprise during a period from transactions and other events and circumstances from non-owner sources. Comprehensive loss includes net loss and the change in accumulated other comprehensive income (loss) for the period. Accumulated other comprehensive loss consisted entirely of unrealized gains and losses on available-for-sale marketable securities during the period ending December 31, 2022 and 2021.

Net Loss per Share

The Company applies the two-class method to compute basic and diluted net loss per share because it has issued shares that meet the definition of participating securities. The two-class method determines net income (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 income (losses) available to common stockholders for the period to be allocated between common and participating securities based upon their respective rights to share in the earnings as if all income (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.

The Company calculates basic net loss per share by dividing net loss by the weighted average number of common shares outstanding, including pre-funded warrants and excluding restricted common stock. The Company calculates diluted net

loss per share by dividing net loss by the weighted average number of common shares outstanding, as applicable, after giving consideration to the dilutive effect of restricted stock awards, restricted stock units, warrants, pre-funded warrants, and stock options that are outstanding during the period.

Income Taxes

Income taxes are recorded in accordance with ASC Topic 740, Income Taxes ("ASC 740"), which provides for deferred taxes using an asset and liability approach. Under this method, deferred income tax assets and liabilities are recognized based on future income tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities, and their respective income tax basis. Deferred income tax assets and liabilities are measured using enacted income tax rates expected to apply to taxable income in the years in which those temporary differences are expected to be recovered or settled.

The Company provides reserves for potential payments of tax to various tax authorities related to uncertain tax positions, as necessary. The tax benefits recorded are based on a determination of whether and how much of a tax benefit taken by the Company in its tax filings or positions is "more likely than not" to be realized following resolution of any uncertainty related to the tax benefit, assuming that the matter in question will be raised by the tax authorities.

The Company is open to examination by the Internal Revenue Service for the tax years ended December 31, 2013 to December 31, 2022. Since the Company is in a U.S. loss carryforward position, carryforward tax attributes generated in prior years may still be adjusted upon future examination if they have or will be used in a future period. The Company is currently not under examination by the Internal Revenue Service or any other jurisdictions for any tax years. The Company has not recorded any interest or penalties on any unrecognized tax benefits since its inception.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The standard requires that a financial asset or a group of financial assets measured at amortized cost basis to be presented at the net amount expected to be collected. Under current GAAP, a company only considered past events and current conditions in measuring an incurred loss. Under ASU 2016-13, the information that a company must consider is broadened in developing an expected credit loss estimate for assets measured either collectively or individually. The use of forecasted information incorporates more timely information in the estimate of expected credit loss. The guidance is applied using a modified retrospective, or prospective approach, depending on a specific amendment. In November 2019, the FASB deferred the effective date for smaller reporting companies to fiscal years beginning after December 15, 2022. The Company does not anticipate a material impact to its net financial position or disclosures as a result of the adoption of ASU 2016-13.

Fair Value of Financial Assets and Liabilities

12 Months Ended

Dec. 31, 2022

Fair Value of Financial Assets and Liabilities

Fair Value of Financial Assets and Liabilities

3. Fair Value of Financial Assets and Liabilities

The following tables summarize the assets and liabilities measured at fair value on a recurring basis at December 31, 2022 and 2021 (in thousands):


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	98,073	$	98,073	$	—	$	—
Marketable securities:
U.S. Treasury obligations		212,086		212,086		—		—
Total assets	$	310,159	$	310,159	$	—	$	—


	Fair Value Measurements at December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	188,493	$	188,493	$	—	$	—
Marketable securities:
U.S. Treasury obligations		40,159		40,159		—		—
Total assets	$	228,652	$	228,652	$	—	$	—

Cash, cash equivalents and marketable securities are Level 1 assets and include investments in money market funds and U.S. government securities that are valued using quoted market prices. Accordingly, money market funds and government funds are categorized as Level 1 as of December 31, 2022 and 2021. There were no transfers of assets between fair value measurement levels during the years ended December 31, 2022 and 2021.

The carrying amounts reflected in the balance sheets for prepaid expenses and other current assets, accounts payable, and accrued expenses approximate their fair values at December 31, 2022 and 2021, due to their short-term nature.

The Company believes the terms of its debt reflect current market conditions for an instrument with similar terms and maturity, therefore the carrying value of the Company's debt approximates its fair value based on Level 3 of the fair value hierarchy.

- Definition

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

+ References + Details

Marketable Securities

12 Months Ended

Dec. 31, 2022

Marketable Securities

Marketable Securities

4. Marketable Securities

The following table summarizes the Company’s investments as of December 31, 2022 (in thousands):


			Gross
	Amortized		Unrealized				Estimated
	Cost		Gains		Losses		Fair Value
Marketable securities available-for-sale:
U.S. Treasury obligations	$	212,970	$	—	$	(884)	$	212,086
Total available-for-sale securities	$	212,970	$	—	$	(884)	$	212,086

The following table summarizes the Company’s investments as of December 31, 2021 (in thousands):


			Gross
	Amortized		Unrealized				Estimated
	Cost		Gains		Losses		Fair Value
Marketable securities available-for-sale:
U.S. Treasury obligations	$	40,194	$	—	$	(35)	$	40,159
Total available-for-sale securities	$	40,194	$	—	$	(35)	$	40,159

The aggregate fair value of marketable securities with unrealized losses was $212.1 million and $30.2 million at December 31, 2022 and 2021, respectively. At December 31, 2022 and 2021, 23 investments and three investments, respectively, were in an unrealized loss position. All such investments have been in an unrealized loss position for less than a year and these losses are considered temporary. The Company has the ability and intent to hold these investments until a recovery of their amortized cost, which may not occur until maturity.

Property and Equipment, Net

12 Months Ended

Dec. 31, 2022

Property and Equipment, Net

Property and Equipment, Net

5. Property and Equipment, Net

At December 31, 2022 and 2021, property and equipment consists of the following (in thousands):


	December 31,		December 31,
	2022		2021
Laboratory equipment	$	10,298	$	9,497
Leasehold improvements		5,160		5,160
Computer equipment & software		1,080		1,080
Furniture & fixtures		1,002		995
Machinery & equipment		75		75
Construction in progress		—		48
		17,615		16,855
Less: Accumulated depreciation and amortization		(10,231)		(7,291)
	$	7,384	$	9,564

Depreciation and amortization expense was $3.0 million and $2.6 million for the years ended December 31, 2022 and 2021, respectively.

Accrued Expenses

12 Months Ended

Dec. 31, 2022

Accrued Expenses

Accrued Expenses

6. Accrued Expenses

At December 31, 2022 and 2021, accrued expenses consist of the following (in thousands):


	As of
	December 31,		December 31,
	2022		2021
Accrued external research and development expense	$	15,178	$	8,428
Accrued payroll and related expenses		6,800		7,147
Accrued professional and consulting expense		1,510		1,421
Accrued other		833		460
	$	24,321	$	17,456

Preferred Stock

12 Months Ended

Dec. 31, 2022

Preferred Stock

Preferred Stock

7. Preferred Stock

The Board of Directors or any authorized committee thereof is expressly authorized, to the fullest extent permitted by law, to provide by resolution or resolutions for, out of the unissued shares of Preferred Stock, the issuance of the shares of Preferred Stock in one or more series of such stock, and by filing a certificate of designations pursuant to applicable law of the State of Delaware, to establish or change from time to time the number of shares of each such series, and to fix the designations, powers, including voting powers, full or limited, or no voting powers, preferences and the relative, participating, optional or other special rights of the shares of each series and any qualifications, limitations and restrictions thereof.

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Common Stock

12 Months Ended

Dec. 31, 2022

Common Stock.

Common Stock

8. Common Stock

In June 2022, the Company entered into a securities purchase agreement relating to the issuance and sale of an aggregate of 16,326,530 shares of its common stock, pre-funded warrants to purchase 25,510,205 shares of its common stock and associated common warrants to purchase 10,459,181 shares of its common stock. The offering price per share and associated common warrant was $4.90 and the offering price per pre-funded warrant and associated common warrant was $4.8999, which equals the per share public offering price for the common shares less the $0.0001 exercise price for each such pre-funded warrant. The pre-funded warrants are exercisable at any time and only expire when exercised in full. Each common warrant has an exercise price per share of $7.35 (150% of the offering price per share of the common stock), is immediately exercisable and will expire on December 31, 2025. The offering was made pursuant to a registration statement on Form S-3. Gross proceeds from the transaction were $205.0 million and the Company received $195.3 million in net proceeds, after deducting placement agent fees and offering expenses. The pre-funded warrants and warrants meet the

condition for equity classification and were therefore recorded as a component of stockholders’ equity within additional paid-in capital.

The Company has had a sales agreement in place during various time periods with Jefferies LLC (“Jefferies”) with respect to an at-the-market (“ATM”) offering program. Under this program, the Company is able to offer and sell, from time to time at its sole discretion, shares of its common stock through Jefferies as its sales agent. In an ATM offering, exchange-listed companies incrementally sell newly issued shares into the secondary trading market through a designated broker-dealer at prevailing market prices. The current agreement, established in November 2022, allows for the sale of shares of common stock having an aggregate offering price of up to $100 million. As of December 31, 2022, no sales have been transacted under the current agreement. In October 2021, 500,000 shares of common stock were sold pursuant to an ATM, resulting in net proceeds of approximately $13.1 million.

In October 2020, the Company entered into an underwriting agreement relating to the issuance and sale of an aggregate of 3,717,948 shares of its common stock at $39.00 per share and pre-funded warrants to purchase 2,179,487 shares of its common stock. The price of each pre-funded warrant was $38.9999, which equals the per share public offering price for the common shares less the $0.0001 exercise price for each such pre-funded warrant. Total gross proceeds of the transaction were $230.0 million and net proceeds were $215.9 million, after deducting underwriting discounts and commissions and offering expenses. The pre-funded warrants are exercisable at any time, do not expire, and meet the condition for equity classification and were therefore recorded as a component of stockholders’ equity within additional paid-in capital.

In June and July 2019, the Company sold 3,450,000 shares of its common stock, including the exercise of the overallotment option, through an underwritten public offering at a price of $15.00 per share. The offering was made pursuant to the Company’s effective shelf registration statement on Form S‑3. The Company received aggregate net proceeds, after underwriting discounts and commissions and other offering expenses, of approximately $48.3 million.

Shares Reserved For Future Issuance

As of December 31, 2022, the Company had common shares reserved for issuance as follows:


		As of
		December 31,
		2022
Common shares reserved for exercise of pre-funded warrants		27,689,692
Common shares reserved for issuance upon exercise or conversion of outstanding warrants		10,459,181
Common shares reserved for exercise of outstanding stock options under the 2017 and 2018 Plans		4,992,784
Common shares reserved for unvested restricted stock units under the 2018 Plan		1,667,522
Common shares reserved for exercise of outstanding stock options under the 2022 Inducement Plan		1,250,000
Common shares reserved for future issuance under the 2018 Plan		1,063,499
Common shares reserved for future issuance under the 2022 Inducement Plan		750,000
Common shares reserved for future issuance under the 2018 ESPP		1,489,463
		49,362,141

Equity-Based Compensation

12 Months Ended

Dec. 31, 2022

Equity-Based Compensation

Equity-Based Compensation

9. Equity-Based Compensation

Equity Plans

As of December 31, 2022, the Company has four active equity plans, the 2018 Stock Option and Incentive Plan (the “2018 Plan”), the 2017 Stock Option and Incentive Plan (the “2017 Plan”), the 2018 Employee Stock Purchase Plan (the “2018 ESPP”) and the 2022 Inducement Equity Plan (the “2022 Inducement Plan”).

2018 Stock Option and Incentive Plan

The 2018 Plan was adopted by the Board of Directors on May 2, 2018, and approved by the Company’s stockholders on May 11, 2018. The 2018 Plan has replaced the 2017 Plan as no additional awards will be granted under that plan following the consummation of the IPO. At December 31, 2022 there were 1,063,499 shares available to grant under the 2018 Plan.

The 2018 Plan provides for the grant of equity-based incentive awards, including incentive stock options, non-qualified stock options, restricted stock awards, unrestricted stock awards and restricted stock units to the Company’s officers, employees, directors and other key persons (including consultants). Stock options and restricted stock units granted under the 2018 Plan to employees generally vest over four years. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2018 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

The 2018 Plan provides that the number of shares reserved and available for issuance under the plan will automatically increase each January 1, beginning on January 1, 2019, by 4% of the outstanding number of shares of common stock on the immediately preceding December 31 or such lesser number of shares as determined by the Board of Directors or compensation committee (the “Annual Increase”). These limits are subject to adjustment in the event of a stock split, stock dividend or other change in the Company’s capitalization.

2017 Stock Option and Incentive Plan

The 2017 Plan provides for the grant of incentive stock options, non-qualified stock options, restricted stock awards, unrestricted stock awards and restricted stock units. Stock options granted under the 2017 Plan to employees generally vest over four years. The Company no longer issues grants from the 2017 Plan. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2017 Plan will be added back to the shares of common stock available for issuance under the 2018 Plan.

2018 Employee Stock Purchase Plan

On May 2, 2018, the Board of Directors adopted the 2018 ESPP, and it was approved by the stockholders on May 11, 2018. At December 31, 2022 there were 1,489,463 shares available to grant under the 2018 ESPP and no shares had been issued. The ESPP provides that the number of shares reserved and available for issuance will automatically increase each January 1, beginning on January 1, 2019 through January 1, 2028, by the lesser of (i) 353,614 shares of common stock, (ii) 1% of the outstanding number of shares of the Company’s common stock on the immediately preceding December 31 or (iii) such lesser number of shares as determined by the 2018 ESPP administrator. The number of shares reserved under the 2018 ESPP is subject to adjustment in the event of a stock split, stock dividend or other change in the Company’s capitalization.

2022 Inducement Equity Plan

The 2022 Inducement Plan was approved by the Board of Directors on June 16, 2022 and provides for the grant of non-qualified stock options, stock appreciation rights, restricted stock awards, restricted stock units, unrestricted stock awards and dividend equivalent rights to individuals that were not previously an employee or director of the Company or individuals returning to employment after a bona fide period of non-employment with the Company. Stock options and restricted stock units granted under the 2022 Inducement Plan to employees generally vest over four years. The shares of common stock underlying any awards that are forfeited, cancelled, repurchased or are otherwise terminated by the Company under the 2022 Inducement Plan will be added back to the shares of common stock available for issuance under the 2022 Inducement Plan. The 2022 Inducement Plan was approved for 1,000,000 shares of common stock in June 2022 and an additional 1,000,000 shares of common stock were added in September 2022. At December 31, 2022 there were 750,000 shares available to grant under the 2022 Inducement Plan.

Total Equity-Based Compensation Expense

The Company recorded equity-based compensation expense related to all equity-based awards, which was allocated as follows in the consolidated statements of operations and comprehensive loss for the years ended December 31, 2022 and 2021 (in thousands):


	Year Ended
	December 31,
	2022		2021
Research and development expense	$	12,926	$	10,176
General and administrative expense		14,775		12,973
	$	27,701	$	23,149

Equity-based compensation during the year ended December 31, 2022 includes $2.0 million related to the modification of certain equity awards.

The following table summarizes the Company’s unrecognized equity-based compensation expense as of December 31, 2022:



	As of December 31, 2022
		Unrecognized Expense (in thousands)	Weighted Average Remaining Period of Recognition (years)
Restricted Stock Units		16,533	2.6
Stock Options		35,786	2.6
	$	52,319

Restricted Stock Units

The following table summarizes the Company’s restricted stock unit activity for the current year:


		Weighted
		Average Grant
	Number of Units	Date Fair Value
Restricted stock units as of December 31, 2021	314,901	$	47.38
Granted	1,745,350	$	10.97
Vested	(92,100)	$	43.79
Forfeited	(300,629)	$	21.31
Restricted stock units as of December 31, 2022	1,667,522	$	14.17

The total fair value of restricted stock units vested during the year ended December 31, 2022 was $1.3 million.

Stock Options

The following table summarizes the Company’s stock option activity for the current year:


				Weighted
		Weighted		Average
	Number of	Average		Remaining	Aggregate
	Shares	Exercise Price		Contractual Term	Intrinsic Value
				(in years)	(in thousands)
Outstanding as of December 31, 2021	3,743,400	$	25.55	8.06	$	26,272
Granted	3,429,026	$	9.95
Exercised	(44,850)	$	11.04
Cancelled	(884,792)	$	25.33
Outstanding as of December 31, 2022	6,242,784	$	17.12	7.74	$	5,835
Options exercisable as of December 31, 2022	2,466,054	$	20.23	5.87	$	1,520

Using the Black-Scholes option pricing model, the weighted average fair value of options granted during the year ended December 31, 2022 was $7.36.

The following weighted average assumptions were used in determining the fair value of options granted in the years ended December 31, 2022 and 2021:


	Year Ended
	December 31,
	2022		2021
Risk-free interest rate	3.07	%	0.86	%
Expected dividend yield	0.0	%	0.0	%
Expected term (years to liquidity)	5.99		6.22
Expected volatility	88.63	%	87.62	%

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Taxes

Income Taxes

10. Income Taxes

The Company has not recorded a current or deferred tax provision for the years ended December 31, 2022 and 2021.

The effective income tax rate differed from the amount computed by applying the federal statutory rate to the Company’s loss before income taxes as follows:


	For Year Ended
	December 31,
	2022		2021
Tax effected at statutory rate	21.0	%	21.0	%
State taxes	6.8		6.8
Stock compensation	(2.0)		0.9
Non-deductible expenses	(0.6)		(1.6)
Federal research and development credits	7.5		6.5
Other	(0.7)		(1.5)
Change in valuation allowance	(32.0)		(32.1)
	—	%	—	%

Deferred tax assets (liabilities) consist of the following at December 31, 2022 and 2021 (in thousands):


	As of
	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	93,505	$	82,403
Tax credits		36,785		25,800
Capitalized Research & Development		27,446		—
Stock based compensation		7,489		4,751
Operating lease liability		5,329		7,365
Reserve and accruals		2,579		2,844
Deferred revenue		—		9,035
Total gross deferred tax assets		173,133		132,198
Valuation allowance		(167,275)		(124,233)
Total deferred tax assets		5,858		7,965
Total deferred tax liabilities:
Operating lease right-of-use asset		(5,029)		(6,925)
Fixed and intangible assets		(829)		(1,040)
Total deferred tax liabilities		(5,858)		(7,965)
Total net deferred tax assets	$	—	$	—

Total Net Deferred Tax Assets

Deferred tax assets are reduced by a valuation allowance if, based on the weight of available positive and negative evidence, it is more likely than not that some portion or all of the deferred tax assets will not be realized. Accordingly, a full valuation allowance has been established against the net deferred tax assets as of December 31, 2022 and 2021. The valuation allowance for deferred tax assets increased by $43.0 million and $42.3 million in 2022 and 2021, respectively. This increase mainly relates to the establishment of a valuation allowance against the Company’s net domestic deferred tax assets in connection with net operating losses generated in each year, capitalized research expenses and additional tax credit carryforwards generated. Starting with tax years beginning after December 31, 2021, entities are required to capitalize all research and experimentation “R&D” expenses as defined under Section 174 of the Internal Revenue Code and amortize them over five years for domestic expenses and over fifteen years for foreign expenses. During the year, the Company capitalized $101.2 million of R&D expenses, net of current year amortization deductions. The corresponding deferred tax asset as of December 31, 2022 is $27.4 million. As of December 31, 2022, the Company had approximately $343.0 million and $339.8 million of Federal and State operating loss carryforwards respectively, which begin to expire in 2032, except for $292.5 million of the Company’s federal net operating loss carryforwards that do not expire. These loss carryforwards may be available to reduce future taxable income, if any. These loss carryforwards are subject to review and possible adjustment by the appropriate taxing authorities. As of December 31, 2022, the Company also had federal and state credit carryovers of $32.6 million and $5.3 million, respectively, which begin to expire in 2034 and 2023, respectively. The amount of loss and credit carryforwards that may be utilized in any future period may be limited based upon changes in the ownership of the Company’s ultimate parent. Additionally, the deductibility of federal net operating losses generated after December 31, 2017 is limited to 80% of the Company’s taxable income in any future taxable year.

The Company follows the provisions of ASC 740-10, “Accounting for Uncertainty in Income Taxes,” which specifies how tax benefits for uncertain tax positions are to be recognized, measured, and recorded in financial statements; requires certain disclosures of uncertain tax matters; specifies how reserves for uncertain tax positions should be classified on the balance sheet; and provides transition and interim period guidance, among other provisions. As of December 31, 2022 and 2021, the Company has not recorded any amounts for uncertain tax positions. The Company’s policy is to recognize interest and penalties accrued on any uncertain tax positions as a component of income tax expense, if any, in its statements of income.

The Company’s net operating loss and tax credit 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 percent as defined under Section 382 and 383 of the U.S. Internal Revenue Code of 1986, respectively, as well as similar state provisions. The amount of the annual limitation is determined based on the value of the Company immediately prior to the ownership change. The Company conducted a Section 382 study covering the period of November 26, 2013 through June 30, 2022. The study concluded that ownership changes occurred during that period which limit the amount of the Company’s net operating losses and tax credit carryforwards that can be utilized before expiring. The carryforwards disclosed represent the amount of attributes that can be utilized based on the results of the study.

All of the Company’s tax years will remain open for examination by the federal and state tax authorities to the extent that the Company's tax attributes are utilized in future years to offset income or income taxes.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies

Commitments and Contingencies

11. Commitments and Contingencies

Operating Leases

620 Memorial Facility Lease

In March 2015, the Company entered into a 5-year lease of office and laboratory space for its corporate headquarters (the “Lease”) at 620 Memorial Drive in Cambridge, Massachusetts. The Lease was amended in February 2018, to add an additional space (the “Expansion Space”) at the current location and to extend the Lease term (the “Amended Lease”). The Amended Lease expires in September 2023. Annual rent payments, including the Expansion Space, increase from $1.4 million to $1.7 million over the term of the Amended Lease. Variable lease payments include the Company’s allocated share of costs incurred and expenditures made by the landlord in the operation and management of the building.

On October 5, 2020, the Company entered into a Sublease Agreement (the “Sublease”) with Orna Therapeutics, Inc. (the “Subtenant”) to sublease the space covered by the Amended Lease at 620 Memorial Drive, Cambridge, Massachusetts. The Sublease term commenced on February 1, 2021 and ends on August 31, 2023, unless terminated earlier. The Sublease provides for initial annual base rent of approximately $1.9 million. The Subtenant is obligated to pay for certain costs, taxes and operating expenses, subject to certain exclusions. The Sublease is subordinate to that certain Indenture of Lease, dated March 5, 2015, by and between 620 Memorial Leasehold LLC and Scholar Rock, Inc., as amended.

301 Binney Facility Lease

In November 2019, the Company entered into a lease of office and laboratory space at 301 Binney Street in Cambridge, Massachusetts to be used as its new corporate headquarters. The expiration date of the lease is in August 2025 and the Company has the option to extend the term by two years. The base rent is $6.9 million per year, subject to an annual increase of 3.5%, and the Company was subject to a free-rent period through mid-August 2020. Variable lease payments include the Company’s allocated share of costs incurred and expenditures made by the landlord in the operation and management of the building. The lease included incentives of $14.1 million in the form of an allowance for tenant improvements related to the design and build out of the space. In connection with the lease, the Company has secured a letter of credit for $2.3 million which renews automatically each year. The lease commencement date, for accounting purposes, was reached in September 2020.

Other information related to the Company’s leases (excluding the Company’s sublease income of $2.7 million and $2.3 million for the years ending December 31, 2022 and 2021, respectively) is as follows (in thousands, except lease term and discount rate):


	For Year Ended
	December 31,
	2022
Lease Cost:
Operating lease cost	$	8,675
Variable lease cost		2,080
Total lease cost	$	10,755


	For Year Ended
	December 31,
	2022
Other information:
Operating cash flows used for operating leases	$	9,183
Weighted average remaining lease term		2.5
Weighted average incremental borrowing rate		7.5	%

The following is a maturity analysis of the annual undiscounted cash flows reconciled to the carrying value of the operating lease liabilities as of December 31, 2022 (in thousands):


Year Ending December 31,
2023		9,057
2024		8,051
2025		4,498
Total lease payments		21,606
Less imputed interest		(1,954)
Total operating lease liability	$	19,652
Short-term portion of operating lease liability		7,852
Long-term portion of operating lease liability		11,800

The Company recorded approximately $8.7 million and $8.6 million in rent expense (excluding sublease income) for the years ended December 31, 2022 and 2021, respectively.

Specifica Antibody Library

On December 20, 2019 (the “Effective Date”), the Company entered into a Library Development and Transfer Agreement with Specifica Inc. (“Specifica”), whereby Specifica is responsible for developing and delivering a customized antibody display library (the “Library”) for the Company to use to identify antibodies for further research, development, and commercialization. As of December 31, 2022 the Company has paid $2.9 million of the total $3.7 million in fees expected to be paid through 2023 related to the Library. As the return right has lapsed, all $3.7 million in fees have been recognized as expense to date.

Legal Proceedings

The Company, from time to time, may be party to litigation arising in the ordinary course of its business. The Company was not subject to any material legal proceedings during the years ended December 31, 2022 and 2021.

Debt

12 Months Ended

Dec. 31, 2022

Debt

Debt

12. Debt

On October 16, 2020 (the “Closing Date”) the Company entered into a Loan and Security Agreement with Oxford Finance LLC (“Oxford”) and Silicon Valley Bank (“SVB”) for $50.0 million (the “Loan and Security Agreement”). Tranche 1 of $25.0 million was funded on the Closing Date. The Company had an additional $25.0 million in loan proceeds available under Tranche 2 which was funded in December 2021, in conjunction with Amendment 1. The Loan and Security Agreement was to mature on May 1, 2025 and required interest-only payments through November 2022, with principal payments to commence in December 2022. Pursuant to the Loan and Security Agreement, the Company was required to maintain cash in an SVB account equal to the lesser of 100% of the Company’s consolidated cash or 105% of the dollar amount of the outstanding debt.

On November 10, 2022, the Company entered into Amendment 2 to the Loan and Security Agreement (the “Amendment”) to increase the total agreement to an amount up to $100.0 million, comprised of the original $50.0 million loan which remains outstanding and two additional $25.0 million tranches. The first $25.0 million tranche is available at the Company’s discretion through December 2023 upon achievement of certain development and business performance milestones. The second $25.0 million tranche may be available upon the Company’s request, at Oxford and SVB’s discretion. The Amendment also extended the interest-only payment period for an additional 24 months through November 2024, with principal payments to commence in December 2024, or for an additional 36 months through November 2025 upon achievement of certain development and business performance milestones, with principal payments to commence in December 2025. The maturity of the loan was extended to November 2027.

Effective upon the Amendment, the interest rate on the unpaid principal is the greater of the Wall Street Journal prime rate plus 4.60% or 9.35% per annum. Prepayment is permitted and may include a pre-payment fee ranging from 0% - 3% (of the principal amount being prepaid), depending on when the prepayment is made. The Company is also required to make a final payment equal to 2% of the original principal amount.

In conjunction with the Amendment, the Company was required to pay the accrued portion of the final payment on the previous outstanding balance of $0.9 million.

The following table shows required payments (excluding interest), during the next five years on debt outstanding at December 31, 2022 (in thousands):


Year Ending December 31,	Total future payments
2023	$	—
2024		1,389
2025		16,667
2026		16,667
2027		16,277
Total payments	$	51,000

The Company incurred costs on behalf of the lender recorded as a debt discount of $0.4 million and incurred debt issuance costs of $0.1 million, both of which are recorded as a deduction from the carrying amount of the debt and are being amortized as interest expense over the term of the loan. The final payment fee will be treated as an additional debt discount and accreted to the debt balance over the term.

For the years ended December 31, 2022 and 2021, the Company recorded total interest expense for the debt of $4.7 million and $2.1 million, respectively.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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+ Details

Agreements

12 Months Ended

Dec. 31, 2022

Agreements

Agreements

13. Agreements

Collaboration with Gilead

On December 19, 2018 (the “Effective Date”), the Company entered into a three-year Master Collaboration Agreement (the “Gilead Collaboration Agreement”) with Gilead to discover and develop specific inhibitors of TGFβ activation focused on the treatment of fibrotic diseases. Under the collaboration, Gilead had exclusive options to license worldwide rights to product candidates that emerge from three of the Company’s TGFβ programs (each a “Gilead Program”). Pursuant to the Gilead Collaboration Agreement, the Company was responsible for antibody discovery and preclinical research through product candidate nomination, after which, upon exercising the option for a Gilead Program, Gilead would be responsible for the program’s preclinical and clinical development and commercialization. Such option could have been exercised by Gilead at any time from the Effective Date through a date that is 90 days following the expiration of the Research Collaboration Term for a given Gilead Program (no later than March 19, 2022), or until termination of the Gilead Program, whichever is earlier (the “Option Exercise Period”). On January 6, 2022, Gilead agreed to terminate its option exercise period for all programs.

Revenue associated with the research and development and license performance obligations relating to the Gilead Programs was recognized as revenue as the research and development services were provided, using an input method, according to the costs that were incurred on each Gilead Program and the costs that were expected to be incurred to satisfy the performance obligation. The transfer of control occurred over time. In management’s judgment, this input method was the best measure of progress towards satisfying the performance obligation. The amounts allocated to the three material rights provided by the options (“Material Rights”) was to be deferred on the Company’s consolidated balance sheet until either exercise or termination of the respective options.

A $25.0 million preclinical milestone was achieved in December 2019 for the successful demonstration of efficacy in preclinical in vivo proof-of-concept studies. As a result, the associated $25.0 million was included in the consideration transferred and proportionally allocated to the performance obligations, as it was probable that a future material reversal would not occur.

The Company recognized the revenue related to the research and development services based on a cost input method over the research term for each respective Gilead Program, which spanned from January 2019 through December 2021. In January 2022, upon Gilead’s termination of its option exercise period for all programs, the Company recognized revenue of $33.2 million attributable to the Material Rights in the Company’s consolidated statements of operations and comprehensive loss, after which all revenue related to the Gilead Collaboration Agreement had been fully recognized.

Net Loss per Share

12 Months Ended

Dec. 31, 2022

Net Loss per Share

Net Loss per Share

14. Net Loss per Share

The Company calculates basic net loss per share by dividing net loss by the weighted average number of common shares outstanding, excluding restricted common stock. The weighted average number of common shares used in the basic and diluted net loss per share calculation includes the pre-funded warrants issued in connection with the Company’s November 2020 and June 2022 follow-on offerings as the pre-funded warrants are exercisable at any time for nominal cash consideration. As of December 31, 2022, no pre-funded warrants have been exercised and 27,689,692 pre-funded warrants are outstanding. The Company has generated a net loss in all periods presented, so the basic and diluted net loss per share are the same, as the inclusion of the potentially dilutive securities would be anti-dilutive.

Basic and diluted net loss per share is calculated as follows (in thousands, except share and per share data):


	Year Ended		Year Ended
	December 31, 2022		December 31, 2021
Net loss	$	(134,502)	$	(131,799)
Weighted average common shares outstanding, basic and diluted		59,611,656		36,711,833
Net loss per share, basic and diluted	$	(2.26)	$	(3.59)

The following table sets forth the outstanding common stock equivalents, presented based on amounts outstanding at each period end, that have been excluded from the calculation of diluted net loss per share for the periods indicated because their inclusion would have been anti-dilutive:


	Year Ended December 31,
	2022	2021
Restricted stock units	1,667,522	314,901
Stock options	6,242,784	3,743,400
Warrants	10,459,181	—
	18,369,487	4,058,301

Retirement Plan

12 Months Ended

Dec. 31, 2022

Retirement Plan

Retirement Plan

15. Retirement Plan

The Company sponsors a 401(k) retirement plan, in which substantially all employees are eligible to participate upon employment. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. Effective, January 1, 2020, the Company adopted a policy to match 50% of the employee contributions to the 401(k) plan up to a maximum of 6% of the participating employee’s eligible earnings, resulting in a maximum company match of 3% of the participating employee’s eligible earnings subject to statutory limitations. The Company recognized $0.8 million and $0.7 million in expense related to the match during the years ended December 31, 2022 and 2021, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section S99
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (d)(i)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/topic&trid=2235017

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 3
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-URI https://asc.fasb.org/extlink&oid=6414203&loc=d3e39689-114964

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-Name Accounting Standards Codification
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

Restructuring

12 Months Ended

Dec. 31, 2022

Restructuring

Restructuring

16. Restructuring

On May 16, 2022, the Company announced a reduction in workforce in connection with the restructuring of its business to prioritize and focus on its clinical stage assets. The restructuring resulted in a reduction of the Company’s workforce by 39 positions, or approximately 25%, and occurred during the second quarter of 2022. As a result, the Company recorded restructuring costs of $1.9 million related to severance benefits for the affected employees, including salary continuation, coverage of medical insurance premiums and outplacement services, of which $1.4 million was recorded to research and development expense and $0.5 million was recorded to general and administrative expenses in the second quarter of 2022. At December 31, 2022, all amounts have been paid. The Company also incurred $0.1 million of non-cash expense, during the second quarter of 2022, related to equity modifications associated with the extension of the post-termination option exercise period for the vested portion of the affected employees’ outstanding stock options, as well as modifications of certain restricted stock units.

Summary of Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2022

Summary of Significant Accounting Policies

Basis of Presentation

The consolidated financial statements include the accounts of Scholar Rock Holding Corporation and its wholly owned subsidiaries. All intercompany balances have been eliminated in consolidation.

Use of Estimates

Concentration of Credit Risk and Off-Balance Sheet Risk

Cash, Cash Equivalents and Restricted Cash


	As of December 31,
	2022		2021
Cash and cash equivalents	$	103,275	$	212,835
Restricted cash		2,498		2,498
	$	105,773	$	215,333

Marketable Securities

Property and Equipment


		Estimated Useful Life
		(in Years)
Laboratory equipment		3 – 5
Computer equipment & software		3
Furniture & fixtures		5
Machinery & equipment		3 – 5
Leasehold improvements		Shorter of the useful life or remaining lease term

Impairment of Long-Lived Assets

Leases

Fair Value Measurements

Level 1 — Quoted market prices in active markets for identical assets or liabilities.

Level 2 — Inputs other than Level 1 inputs that are either directly or indirectly observable, such as quoted market prices, interest rates and yield curves.

Level 3 — Unobservable inputs developed using estimates of assumptions developed by the Company, which reflect those that a market participant would use.

Segment Information

Revenue Recognition

For a complete discussion of accounting for collaboration revenues, see Note 13, Agreements.

Research and Development Expenses and Accruals

Equity-Based Compensation

The Company accounts for forfeitures when they occur.

Comprehensive Loss

Net Loss per Share

Income Taxes

Recently Issued Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Summary of Significant Accounting Policies

Schedule of reconciles of cash, cash equivalents and restricted cash


	As of December 31,
	2022		2021
Cash and cash equivalents	$	103,275	$	212,835
Restricted cash		2,498		2,498
	$	105,773	$	215,333

Schedule of useful life of property, plant and equipment


		Estimated Useful Life
		(in Years)
Laboratory equipment		3 – 5
Computer equipment & software		3
Furniture & fixtures		5
Machinery & equipment		3 – 5
Leasehold improvements		Shorter of the useful life or remaining lease term

Fair Value of Financial Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2022

Fair Value of Financial Assets and Liabilities

Schedule of summary of the assets and liabilities measured at fair value on a recurring basis

The following tables summarize the assets and liabilities measured at fair value on a recurring basis at December 31, 2022 and 2021 (in thousands):


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	98,073	$	98,073	$	—	$	—
Marketable securities:
U.S. Treasury obligations		212,086		212,086		—		—
Total assets	$	310,159	$	310,159	$	—	$	—


	Fair Value Measurements at December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Money market funds, included in cash and cash equivalents	$	188,493	$	188,493	$	—	$	—
Marketable securities:
U.S. Treasury obligations		40,159		40,159		—		—
Total assets	$	228,652	$	228,652	$	—	$	—

Marketable Securities (Tables)

12 Months Ended

Dec. 31, 2022

Marketable Securities

Summary of investments

The following table summarizes the Company’s investments as of December 31, 2022 (in thousands):


			Gross
	Amortized		Unrealized				Estimated
	Cost		Gains		Losses		Fair Value
Marketable securities available-for-sale:
U.S. Treasury obligations	$	212,970	$	—	$	(884)	$	212,086
Total available-for-sale securities	$	212,970	$	—	$	(884)	$	212,086

The following table summarizes the Company’s investments as of December 31, 2021 (in thousands):


			Gross
	Amortized		Unrealized				Estimated
	Cost		Gains		Losses		Fair Value
Marketable securities available-for-sale:
U.S. Treasury obligations	$	40,194	$	—	$	(35)	$	40,159
Total available-for-sale securities	$	40,194	$	—	$	(35)	$	40,159

Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2022

Property and Equipment, Net

Summary of property and equipment

At December 31, 2022 and 2021, property and equipment consists of the following (in thousands):


	December 31,		December 31,
	2022		2021
Laboratory equipment	$	10,298	$	9,497
Leasehold improvements		5,160		5,160
Computer equipment & software		1,080		1,080
Furniture & fixtures		1,002		995
Machinery & equipment		75		75
Construction in progress		—		48
		17,615		16,855
Less: Accumulated depreciation and amortization		(10,231)		(7,291)
	$	7,384	$	9,564

Accrued Expenses (Tables)

12 Months Ended

Dec. 31, 2022

Accrued Expenses

Summary of accrued expenses

At December 31, 2022 and 2021, accrued expenses consist of the following (in thousands):


	As of
	December 31,		December 31,
	2022		2021
Accrued external research and development expense	$	15,178	$	8,428
Accrued payroll and related expenses		6,800		7,147
Accrued professional and consulting expense		1,510		1,421
Accrued other		833		460
	$	24,321	$	17,456

Common Stock (Tables)

12 Months Ended

Dec. 31, 2022

Common Stock.

Schedule of reserved common stock


		As of
		December 31,
		2022
Common shares reserved for exercise of pre-funded warrants		27,689,692
Common shares reserved for issuance upon exercise or conversion of outstanding warrants		10,459,181
Common shares reserved for exercise of outstanding stock options under the 2017 and 2018 Plans		4,992,784
Common shares reserved for unvested restricted stock units under the 2018 Plan		1,667,522
Common shares reserved for exercise of outstanding stock options under the 2022 Inducement Plan		1,250,000
Common shares reserved for future issuance under the 2018 Plan		1,063,499
Common shares reserved for future issuance under the 2022 Inducement Plan		750,000
Common shares reserved for future issuance under the 2018 ESPP		1,489,463
		49,362,141

Equity-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Equity-Based Compensation

Summary of allocation of equity-based compensation


	Year Ended
	December 31,
	2022		2021
Research and development expense	$	12,926	$	10,176
General and administrative expense		14,775		12,973
	$	27,701	$	23,149

Summary of unrecognized equity-based compensation expense



	As of December 31, 2022
		Unrecognized Expense (in thousands)	Weighted Average Remaining Period of Recognition (years)
Restricted Stock Units		16,533	2.6
Stock Options		35,786	2.6
	$	52,319

Summary of stock activity


		Weighted
		Average Grant
	Number of Units	Date Fair Value
Restricted stock units as of December 31, 2021	314,901	$	47.38
Granted	1,745,350	$	10.97
Vested	(92,100)	$	43.79
Forfeited	(300,629)	$	21.31
Restricted stock units as of December 31, 2022	1,667,522	$	14.17

Summary of stock option activity


				Weighted
		Weighted		Average
	Number of	Average		Remaining	Aggregate
	Shares	Exercise Price		Contractual Term	Intrinsic Value
				(in years)	(in thousands)
Outstanding as of December 31, 2021	3,743,400	$	25.55	8.06	$	26,272
Granted	3,429,026	$	9.95
Exercised	(44,850)	$	11.04
Cancelled	(884,792)	$	25.33
Outstanding as of December 31, 2022	6,242,784	$	17.12	7.74	$	5,835
Options exercisable as of December 31, 2022	2,466,054	$	20.23	5.87	$	1,520

Schedule of weighted average assumptions in fair value


	Year Ended
	December 31,
	2022		2021
Risk-free interest rate	3.07	%	0.86	%
Expected dividend yield	0.0	%	0.0	%
Expected term (years to liquidity)	5.99		6.22
Expected volatility	88.63	%	87.62	%

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Taxes

Schedule of reconciliation of effective income tax rate


	For Year Ended
	December 31,
	2022		2021
Tax effected at statutory rate	21.0	%	21.0	%
State taxes	6.8		6.8
Stock compensation	(2.0)		0.9
Non-deductible expenses	(0.6)		(1.6)
Federal research and development credits	7.5		6.5
Other	(0.7)		(1.5)
Change in valuation allowance	(32.0)		(32.1)
	—	%	—	%

Summary of deferred tax assets (liabilities)

Deferred tax assets (liabilities) consist of the following at December 31, 2022 and 2021 (in thousands):


	As of
	December 31,
	2022		2021
Deferred tax assets:
Net operating loss carryforwards	$	93,505	$	82,403
Tax credits		36,785		25,800
Capitalized Research & Development		27,446		—
Stock based compensation		7,489		4,751
Operating lease liability		5,329		7,365
Reserve and accruals		2,579		2,844
Deferred revenue		—		9,035
Total gross deferred tax assets		173,133		132,198
Valuation allowance		(167,275)		(124,233)
Total deferred tax assets		5,858		7,965
Total deferred tax liabilities:
Operating lease right-of-use asset		(5,029)		(6,925)
Fixed and intangible assets		(829)		(1,040)
Total deferred tax liabilities		(5,858)		(7,965)
Total net deferred tax assets	$	—	$	—

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2022

Commitments and Contingencies

Summary of lease costs


	For Year Ended
	December 31,
	2022
Lease Cost:
Operating lease cost	$	8,675
Variable lease cost		2,080
Total lease cost	$	10,755


	For Year Ended
	December 31,
	2022
Other information:
Operating cash flows used for operating leases	$	9,183
Weighted average remaining lease term		2.5
Weighted average incremental borrowing rate		7.5	%

Summary of minimum lease payments

The following is a maturity analysis of the annual undiscounted cash flows reconciled to the carrying value of the operating lease liabilities as of December 31, 2022 (in thousands):


Year Ending December 31,
2023		9,057
2024		8,051
2025		4,498
Total lease payments		21,606
Less imputed interest		(1,954)
Total operating lease liability	$	19,652
Short-term portion of operating lease liability		7,852
Long-term portion of operating lease liability		11,800

Debt (Tables)

12 Months Ended

Dec. 31, 2022

Debt

Schedule of future principal payments of loan

The following table shows required payments (excluding interest), during the next five years on debt outstanding at December 31, 2022 (in thousands):


Year Ending December 31,	Total future payments
2023	$	—
2024		1,389
2025		16,667
2026		16,667
2027		16,277
Total payments	$	51,000

Net Loss per Share (Tables)

12 Months Ended

Dec. 31, 2022

Net Loss per Share

Schedule of basic and diluted net loss per share

Basic and diluted net loss per share is calculated as follows (in thousands, except share and per share data):


	Year Ended		Year Ended
	December 31, 2022		December 31, 2021
Net loss	$	(134,502)	$	(131,799)
Weighted average common shares outstanding, basic and diluted		59,611,656		36,711,833
Net loss per share, basic and diluted	$	(2.26)	$	(3.59)

Summary of anti-dilutive securities


	Year Ended December 31,
	2022	2021
Restricted stock units	1,667,522	314,901
Stock options	6,242,784	3,743,400
Warrants	10,459,181	—
	18,369,487	4,058,301

Nature of the Business and Basis of Presentation (Details)	12 Months Ended
	Dec. 31, 2022 item
Nature of the Business and Basis of Presentation
Number of collaborations	2

Summary of Significant Accounting Policies - Risk (Details) $ in Billions	Dec. 31, 2022 USD ($)
Summary of Significant Accounting Policies
Off-balance sheet risk	$ 0

Summary of Significant Accounting Policies - Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash and cash equivalents and restricted cash
Cash and cash equivalents	$ 103,275	$ 212,835
Restricted cash	2,498	2,498
Total	105,773	215,333	$ 162,856
Letter of credit	$ 2,500	$ 2,500

Summary of Significant Accounting Policies - Property and Equipment (Details)	12 Months Ended
	Dec. 31, 2022
Laboratory equipment \| Minimum
Property and Equipment, Net
Estimated Useful Life	3 years
Laboratory equipment \| Maximum
Property and Equipment, Net
Estimated Useful Life	5 years
Computer equipment & software
Property and Equipment, Net
Estimated Useful Life	3 years
Furniture & fixtures
Property and Equipment, Net
Estimated Useful Life	5 years
Machinery & equipment \| Minimum
Property and Equipment, Net
Estimated Useful Life	3 years
Machinery & equipment \| Maximum
Property and Equipment, Net
Estimated Useful Life	5 years

Summary of Significant Accounting Policies - Misc (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) segment	Dec. 31, 2021
Number of operating segments \| segment	1
Adjustment for other than temporary decline in fair value \| $	$ 0
Stock options
Expected dividend yield	0.00%	0.00%

Fair Value of Financial Assets and Liabilities - (Details) - Recurring - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets:
Cash and cash equivalents	$ 98,073	$ 188,493
Marketable securities:
U.S. Treasury obligations	212,086	40,159
Total assets	310,159	228,652
Level 1
Assets:
Cash and cash equivalents	98,073	188,493
Marketable securities:
U.S. Treasury obligations	212,086	40,159
Total assets	$ 310,159	$ 228,652

Marketable Securities - Summary of Investments (Details) $ in Thousands	Dec. 31, 2022 USD ($) security	Dec. 31, 2021 USD ($) security
Marketable securities available-for-sale
Amortized Cost	$ 212,970	$ 40,194
Gross Unrealized Losses	(884)	(35)
Estimated Fair Value	212,086	40,159
Aggregate fair value of marketable securities with unrealized gains (losses) position for less than a year	$ 212,100	$ 30,200
Number of investments in an unrealized loss position for less than a year \| security	23	3
U.S. Treasury obligations
Marketable securities available-for-sale
Amortized Cost	$ 212,970	$ 40,194
Gross Unrealized Losses	(884)	(35)
Estimated Fair Value	$ 212,086	$ 40,159

Property and Equipment, Net (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Property and Equipment, Net
Property and equipment, gross	$ 17,615	$ 16,855
Less: Accumulated depreciation and amortization	(10,231)	(7,291)
Total property and equipment, net	7,384	9,564
Depreciation and amortization expense	2,986	2,627
Laboratory equipment
Property and Equipment, Net
Property and equipment, gross	10,298	9,497
Leasehold improvements
Property and Equipment, Net
Property and equipment, gross	5,160	5,160
Computer equipment & software
Property and Equipment, Net
Property and equipment, gross	1,080	1,080
Furniture & fixtures
Property and Equipment, Net
Property and equipment, gross	1,002	995
Machinery & equipment
Property and Equipment, Net
Property and equipment, gross	$ 75	75
Construction in progress
Property and Equipment, Net
Property and equipment, gross		$ 48

Accrued Expenses (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Accrued Expenses
Accrued external research and development expense	$ 15,178	$ 8,428
Accrued payroll and related expenses	6,800	7,147
Accrued professional and consulting expense	1,510	1,421
Accrued other	833	460
Accrued expenses	$ 24,321	$ 17,456

Common Stock - (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			2 Months Ended	12 Months Ended
	Jun. 30, 2022	Oct. 31, 2021	Oct. 31, 2020	Jul. 31, 2019	Dec. 31, 2022	Dec. 31, 2021
Subsidiary, Sale of Stock [Line Items]
Sale of common shares, net of issuance costs (in shares)	16,326,530		3,717,948	3,450,000
Warrant to purchase			2,179,487
Purchase price (in dollars per share)			$ 39.00	$ 15.00
Warrant purchase price (in dollars per share)			$ 0.0001
Proceeds from stock before issuance costs	$ 205,000		$ 230,000
Proceeds from sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs	$ 195,300		$ 215,900	$ 48,300	$ 195,315	$ 13,095
Pre-funded warrants (in dollars per share)			$ 38.9999
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs					$ 195,315	$ 13,095
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs (in shares)	16,326,530		3,717,948	3,450,000
Pre-funded warrant
Subsidiary, Sale of Stock [Line Items]
Warrant to purchase	25,510,205
Purchase price (in dollars per share)	$ 4.8999
Warrant purchase price (in dollars per share)	$ 0.0001
Common warrant
Subsidiary, Sale of Stock [Line Items]
Warrant to purchase	10,459,181
Purchase price (in dollars per share)	$ 4.90
Warrant purchase price (in dollars per share)	$ 7.35
Common stock offering price percentage	150.00%
ATM Offering
Subsidiary, Sale of Stock [Line Items]
Sale of common shares, net of issuance costs (in shares)		500,000
Proceeds from sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs		$ 13,100
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs (in shares)		500,000
At The Market Offering
Subsidiary, Sale of Stock [Line Items]
Sale of common shares, net of issuance costs (in shares)					0
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs (in shares)					0
At The Market Offering \| Maximum
Subsidiary, Sale of Stock [Line Items]
Sale of common shares, pre-funded warrants and warrants to purchase common shares, net of issuance costs					$ 100,000

Common Stock - Reserved (Details)	Dec. 31, 2022 shares
Class of Stock [Line Items]
Shares reserved for future issuance	49,362,141
Pre-funded warrant
Class of Stock [Line Items]
Shares reserved for future issuance	27,689,692
Common Warrant
Class of Stock [Line Items]
Shares reserved for future issuance	10,459,181
2018 ESPP
Class of Stock [Line Items]
Shares reserved for future issuance	1,489,463
2018 Plan
Class of Stock [Line Items]
Shares reserved for future issuance	1,063,499
Inducement Plan 2022 [Member]
Class of Stock [Line Items]
Shares reserved for future issuance	750,000
Stock options
Class of Stock [Line Items]
Shares reserved for future issuance	4,992,784
Stock options \| Inducement Plan 2022 [Member]
Class of Stock [Line Items]
Shares reserved for future issuance	1,250,000
Restricted stock units \| 2018 Plan
Class of Stock [Line Items]
Shares reserved for future issuance	1,667,522

Equity-Based Compensation - 2017 and 2018 Plan (Details)		12 Months Ended
	May 11, 2018 shares	Dec. 31, 2022 item shares	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award
Number of share-based compensation plans \| item		4
2018 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Unused shares available to be granted (in shares)		1,063,499
Increase as percentage of outstanding shares	4.00%
Vesting period	4 years
2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award
Additional shares authorized under stock-based plans (in shares)	0
Vesting period			4 years

Equity-Based Compensation - 2018 ESPP (Details) - 2018 ESPP - shares		12 Months Ended
	May 02, 2018	Dec. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award
Additional shares authorized under stock-based plans (in shares)	353,614
Increase as percentage of outstanding shares	1.00%
Shares issued		0
Unused shares available to be granted (in shares)		1,489,463

Equity-Based Compensation - 2022 Plan (Details) - Inducement Plan 2022 [Member] - shares	1 Months Ended	12 Months Ended
	Sep. 30, 2022	Dec. 31, 2022	Jun. 30, 2022
Equity-Based Compensation
Vesting period		4 years
Shares authorized for issuance			1,000,000
Additional shares authorized	1,000,000
Unused shares available to be granted (in shares)		750,000

Equity-Based Compensation - Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Equity-based compensation
Equity-based compensation expense	$ 27,701	$ 23,149
Modification of equity awards expense	2,000
Research and development expense
Equity-based compensation
Equity-based compensation expense	12,926	10,176
General and administrative expense
Equity-based compensation
Equity-based compensation expense	$ 14,775	$ 12,973

Equity-Based Compensation - Unrecognized Expense (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)
Equity-based compensation
Unrecognized Expense	$ 52,319
Restricted stock units
Equity-based compensation
Unrecognized Expense	$ 16,533
Weighted Average Remaining Period of Recognition	2 years 7 months 6 days
Stock options
Equity-based compensation
Unrecognized Expense	$ 35,786
Weighted Average Remaining Period of Recognition	2 years 7 months 6 days

Equity-Based Compensation - Restricted stock (Details) - Restricted stock units $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($) $ / shares shares
Number of Shares/Units
Outstanding, beginning (in shares) \| shares	314,901
Granted (in shares) \| shares	1,745,350
Vested (in shares) \| shares	(92,100)
Forfeited (in shares) \| shares	(300,629)
Outstanding, end (in shares) \| shares	1,667,522
Weighted Average Grant Date Fair Value
Outstanding, beginning (in dollars per share) \| $ / shares	$ 47.38
Granted (in dollars per share) \| $ / shares	10.97
Vested (in dollars per share) \| $ / shares	43.79
Forfeited (in dollars per share) \| $ / shares	21.31
Outstanding, end (in dollars per share) \| $ / shares	$ 14.17
Fair value of non-option awards vested \| $	$ 1.3

Equity-Based Compensation - Stock Options (Details) - Stock options - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Number of Units
Outstanding, beginning (in shares)	3,743,400
Granted (in shares)	3,429,026
Exercised (in shares)	(44,850)
Cancelled (in shares)	(884,792)
Outstanding, end (in shares)	6,242,784	3,743,400
Options exercisable, end (in shares)	2,466,054
Weighted Average Exercise Price
Outstanding, beginning (in dollars per share)	$ 25.55
Granted (in dollars per share)	9.95
Exercised (in dollars per share)	11.04
Cancelled (in dollars per share)	25.33
Outstanding, end (in dollars per share)	17.12	$ 25.55
Options exercisable, end (in dollars per share)	$ 20.23
Stock options
Weighted average remaining contractual term	7 years 8 months 26 days	8 years 21 days
Weighted average remaining contractual term, exercisable	5 years 10 months 13 days
Aggregate intrinsic value, beginning	$ 26,272
Aggregate intrinsic value, end	5,835	$ 26,272
Aggregate intrinsic value, exercisable	$ 1,520
Weighted average grant date fair value (in dollars per share)	$ 7.36

Equity-Based Compensation - Assumptions (Details) - Stock options	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Assumptions used in determining the fair value of options
Risk-free interest rate	3.07%	0.86%
Expected dividend yield	0.00%	0.00%
Expected term (years to liquidity)	5 years 11 months 26 days	6 years 2 months 19 days
Expected volatility	88.63%	87.62%

Income Taxes - Reconciliation (Details)	12 Months Ended
Income Taxes - Reconciliation (Details)	Dec. 31, 2022	Dec. 31, 2021
Effective income tax rate
Tax effected at statutory rate	21.00%	21.00%
State taxes	6.80%	6.80%
Stock compensation	(2.00%)	0.90%
Non deductible expenses	(0.60%)	(1.60%)
Federal research and development credits	7.50%	6.50%
Other	(0.70%)	(1.50%)
Change in valuation allowance	(32.00%)	(32.10%)

Income Taxes - Deferred Tax Assets (Liabilities) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Net operating loss carryforwards	$ 93,505	$ 82,403
Tax credits	36,785	25,800
Capitalized Research & Development	27,446
Stock based compensation	7,489	4,751
Operating lease liability	5,329	7,365
Reserve and accruals	2,579	2,844
Deferred revenue		9,035
Total gross deferred tax assets	173,133	132,198
Valuation allowance	(167,275)	(124,233)
Total deferred tax assets	5,858	7,965
Operating lease right-of-use asset	(5,029)	(6,925)
Fixed and intangible assets	(829)	(1,040)
Total deferred tax liabilities	$ (5,858)	$ (7,965)

Income Taxes - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Tax Contingency
Increase in valuation allowance for deferred tax assets	$ 43,000	$ 42,300
Capitalized research and development additions	101,200
Capitalized Research & Development	27,446
Uncertain tax position	0	$ 0
Federal
Income Tax Contingency
Net operating loss carryforwards	343,000
Operating loss carryforwards without expiration date	292,500
Tax credit carryforward amount	32,600
State
Income Tax Contingency
Net operating loss carryforwards	339,800
Tax credit carryforward amount	$ 5,300

Commitments and Contingencies (Details) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
	Oct. 05, 2020	Nov. 30, 2019	Feb. 28, 2018	Dec. 31, 2022	Dec. 31, 2021	Mar. 31, 2015
Leased assets
Rent for facility lease				$ 8,700	$ 8,600
Letter of credit				2,500	2,500
Sublease income				2,700	$ 2,300
Lease Cost:
Operating lease cost				8,675
Variable lease cost				2,080
Total lease cost				10,755
Operating cash flows used for operating leases				$ 9,183
Weighted average remaining lease term				2 years 6 months
Weighted average incremental borrowing rate				7.50%
Payment made on commitment				$ 2,900
Payment commitment				3,700
Antibody library expense				$ 3,700
620 Memorial Drive, Cambridge MA
Leased assets
Term of lease						5 years
Option to extend the term			true
Sublease annual base rent	$ 1,900
620 Memorial Drive, Cambridge MA \| Minimum
Leased assets
Rent for facility lease			$ 1,400
620 Memorial Drive, Cambridge MA \| Maximum
Leased assets
Rent for facility lease			$ 1,700
301 Binney St, Cambridge MA
Leased assets
Option to extend the term		true
Renewal term		2 years
Base rent		$ 6,900
Annual upward adjustment (as a percent)		3.50%
Incentive to lease		$ 14,100
Letter of credit		$ 2,300

Commitments and Contingencies - Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Maturity analysis of the annual undiscounted cash flows
2023	$ 9,057
2024	8,051
2025	4,498
Total lease payments	21,606
Less imputed interest	(1,954)
Total operating lease liability	19,652
Short-term portion of operating lease liability	7,852	$ 7,407
Long-term portion of operating lease liability	$ 11,800	$ 19,652

Debt (Details) - USD ($) $ in Thousands			12 Months Ended
Debt (Details) - USD ($) $ in Thousands	Nov. 10, 2022	Oct. 16, 2020	Dec. 31, 2021
Debt
Proceeds from credit facility			$ 24,984
Loan and Security Agreement
Debt
Line of credit maximum	$ 100,000	$ 50,000
Line of credit, outstanding	$ 50,000
Proceeds from credit facility		$ 25,000	$ 25,000
Interest only period	24 months
Upon achievements interest only period	36 months
Final payment fee (as a percent)	2.00%
Repayments of debt	$ 900
Percentage of dollar value of company's consolidated cash		100.00%
Amount of cash required in a lender's account as a percentage of outstanding obligation (as a percent)		105.00%
Loan and Security Agreement \| Minimum
Debt
Prepayment penalty (as a percent)	0.00%
Loan and Security Agreement \| Maximum
Debt
Debt instrument, effective interest rate (as a percent)	9.35%
Prepayment penalty (as a percent)	3.00%
Loan and Security Agreement \| Tranche One
Debt
Remaining borrowing capacity	$ 25,000
Loan and Security Agreement \| Tranche Two
Debt
Remaining borrowing capacity	$ 25,000
Loan and Security Agreement \| Wall Street Journal prime rate
Debt
Variable rate (as a percent)	4.60%

Debt - Future Payments (Details) - USD ($) $ in Thousands	12 Months Ended
Debt - Future Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt
2024	$ 1,389
2025	16,667
2026	16,667
2027	16,277
Total payments	51,000
Interest expense	4,700	$ 2,100
Loan and Security Agreement
Debt
Debt discount	400
Debt issuance costs payment	$ 100

Agreements - Gilead (Details) - USD ($) $ in Thousands		1 Months Ended		12 Months Ended
Agreements - Gilead (Details) - USD ($) $ in Thousands	Dec. 19, 2018	Jan. 31, 2022	Dec. 31, 2019	Dec. 31, 2022	Dec. 31, 2021
Agreements
Revenue earned				$ 33,193	$ 18,816
Gilead
Agreements
Revenue proceeds			$ 25,000
Revenue earned		$ 33,200
Master collaboration agreement, term	3 years

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Net Loss per Share - Calculation (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Loss per share
Net loss	$ (134,502)	$ (131,799)
Weighted average common shares outstanding, basic (in shares)	59,611,656	36,711,833
Weighted average common shares outstanding, diluted (in shares)	59,611,656	36,711,833
Net loss per share, basic (in dollars per share)	$ (2.26)	$ (3.59)
Net loss per share, diluted (in dollars per share)	$ (2.26)	$ (3.59)

- Definition

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

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- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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- Definition

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

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+ Details

Net Loss per Share - Antidilutive (Details) - shares	12 Months Ended
Net Loss per Share - Antidilutive (Details) - shares	Dec. 31, 2022	Dec. 31, 2021
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	18,369,487	4,058,301
Restricted stock units
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	1,667,522	314,901
Stock options
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	6,242,784	3,743,400
Common Warrant
Anti-dilutive securities
Anti-dilutive securities excluded from the calculation of net loss per share	10,459,181
Pre-funded warrant
Anti-dilutive securities
Outstanding warrants	27,689,692

Retirement Plan (Details) - USD ($) $ in Millions		12 Months Ended
Retirement Plan (Details) - USD ($) $ in Millions	Jan. 01, 2020	Dec. 31, 2022	Dec. 31, 2021
Retirement Plan
Matching contribution 401(k)	50.00%
Matching contribution per employee	6.00%
Employer matching contribution	3.00%
Company contributions		$ 0.8	$ 0.7

Restructuring (Details) $ in Millions	3 Months Ended
Restructuring (Details) $ in Millions	Jun. 30, 2022 USD ($) position
Restructuring
Number of positions eliminated \| position	39
Expected number of positions eliminated (as a percent)	25.00%
Restructuring charges	$ 1.9
Non-cash equity modifications expense	0.1
Research and development expense
Restructuring
Restructuring charges	1.4
General and administrative expense
Restructuring
Restructuring charges	$ 0.5