0000950170-23-020851 | 10-Q | XBRL Viewer

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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2023	May 07, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Trading Symbol	SLDB
Entity Registrant Name	Solid Biosciences Inc.
Entity Current Reporting Status	Yes
Entity Central Index Key	0001707502
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Shell Company	false
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		19,601,539
Entity File Number	001-38360
Entity Tax Identification Number	90-0943402
Entity Address, Address Line One	500 Rutherford Avenue
Entity Address, City or Town	Third FloorCharlestown
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02129
City Area Code	617
Local Phone Number	337-4680
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock $0.001 par value per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 164,649	$ 155,384
Available-for-sale securities	20,860	58,338
Prepaid expenses and other current assets	5,095	5,916
Total current assets	190,604	219,638
Operating lease, right-of-use assets	28,306	28,949
Property and equipment, net	8,607	9,657
Other non-current assets	238	175
Restricted cash	1,833	1,833
Total assets	229,588	260,252
Current liabilities:
Accounts payable	5,595	3,238
Accrued expenses	12,384	16,691
Operating lease liabilities	1,863	1,897
Finance liabilities and finance lease liabilities	396	668
Other current liabilities	55	14
Total current liabilities	20,293	22,508
Operating lease liabilities, excluding current portion	23,912	24,279
Finance liabilities and finance lease liabilities, excluding current portion	1,596	1,703
Other non-current liabilities		96
Total liabilities	45,801	48,586
Commitments and contingencies (Note 13)
Preferred stock, $0.001 par value; 10,000,000 shares authorizedat March 31, 2023 and December 31, 2022; no shares issued and outstanding at March 31, 2023 and December 31, 2022
Common stock, $0.001 par value; 60,000,000 shares authorized at March 31, 2023 and December 31, 2022; 19,573,132 shares issued and outstanding at March 31, 2023 and 19,556,732 shares issued and outstanding at December 31, 2022	20	20
Additional paid-in capital	776,570	774,452
Accumulated other comprehensive income (loss)	5	(68)
Accumulated deficit	(592,808)	(562,738)
Total stockholders’ equity	183,787	211,666
Total liabilities and stockholders’ equity	$ 229,588	$ 260,252

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
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	60,000,000	60,000,000
Common stock, shares issued	19,573,132	19,556,732
Common stock, shares outstanding	19,573,132	19,556,732

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Collaboration revenue - related party		$ 1,925
Operating expenses:
Research and development	$ 24,631	19,945
General and administrative	7,399	7,352
Total operating expenses	32,030	27,297
Loss from operations	(32,030)	(25,372)
Other income, net:
Interest income, net	1,678	54
Other income (loss), net	282	(10)
Total other income, net	1,960	44
Net loss	$ (30,070)	$ (25,328)
Net loss per share attributable to common stockholders, basic	$ (1.54)	$ (3.37)
Net loss per share attributable to common stockholders, diluted	$ (1.54)	$ (3.37)
Weighted average shares of common stock outstanding, basic	19,567,635	7,507,155
Weighted average shares of common stock outstanding, diluted	19,567,635	7,507,155

Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Statement of Comprehensive Income [Abstract]
Net loss	$ (30,070)	$ (25,328)
Other comprehensive loss:
Unrealized gain (loss) on available-for-sale securities	73	(6)
Comprehensive loss	$ (29,997)	$ (25,334)

- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income. Excludes changes in equity resulting from investments by owners and distributions to owners.

+ References + Details

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

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+ Details

Condensed Consolidated Statements of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2021	$ 208,211	$ 7	$ 685,006	$ (45)	$ (476,757)
Beginning balance, units at Dec. 31, 2021		7,499,905
Equity-based compensation	2,612		2,612
Exercise of pre-funded warrants	22		22
Vesting of restricted stock, units		18,845
Unrealized gain (loss) on available-for-sale securities	(6)			(6)
Net loss	(25,328)				(25,328)
Ending balance at Mar. 31, 2022	185,511	$ 7	687,640	(51)	(502,085)
Ending balance, units at Mar. 31, 2022		7,518,750
Beginning balance at Dec. 31, 2022	211,666	$ 20	774,452	(68)	(562,738)
Beginning balance, units at Dec. 31, 2022		19,556,732
Equity-based compensation	2,118		2,118
Vesting of restricted stock, units		16,400
Unrealized gain (loss) on available-for-sale securities	73			73
Net loss	(30,070)				(30,070)
Ending balance at Mar. 31, 2023	$ 183,787	$ 20	$ 776,570	$ 5	$ (592,808)
Ending balance, units at Mar. 31, 2023		19,573,132

- Definition

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

+ Details

- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (30,070)	$ (25,328)
Adjustments to reconcile net loss to net cash used in operating activities:
Amortization of (discount) premium on available-for-sale securities	(215)	371
Equity-based compensation expense	2,118	2,612
Depreciation and impairment expense	1,077	709
Changes in operating assets and liabilities:
Prepaid expenses and other current and non-current assets	1,261	(3,366)
Accounts receivable - related party		96
Accounts payable	2,745	71
Accrued expenses and other current and non-current liabilities	(4,911)	(445)
Deferred revenue- related party, current and non-current		(1,910)
Net cash used in operating activities	(27,995)	(27,190)
Cash flows from investing activities:
Purchases of property and equipment	(506)	(184)
Proceeds from sale and maturities of available-for-sale securities	37,766	46,808
Purchases of available-for-sale securities		(8,881)
Net cash provided in investing activities	37,260	37,743
Cash flows from financing activities:
Proceeds from exercise of warrants		22
Net cash provided by financing activities		22
Net increase in cash, cash equivalents and restricted cash	9,265	10,575
Cash, cash equivalents, and restricted cash at beginning of period	157,217	121,206
Cash, cash equivalents, and restricted cash at end of period	$ 166,482	131,781
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment included in accounts payable and accruals		$ 264

Nature of the Business and Basis of Presentation

3 Months Ended

Mar. 31, 2023

Accounting Policies [Abstract]

Nature of the Business and Basis of Presentation

1. Nature of the Business and Basis of Presentation

Nature of Business

Solid Biosciences Inc. was organized in March 2013 under the name SOLID Ventures Management, LLC and operated as a Delaware limited liability company until immediately prior to the effectiveness of its registration statement on Form S-1 on January 25, 2018, at which time it completed a statutory corporate conversion into a Delaware corporation and changed its name to Solid Biosciences Inc. (the “Company”). On December 2, 2022, the Company completed its acquisition of AavantiBio, Inc. (“AavantiBio”), a privately held gene therapy company focused on transforming the lives of patients with Friedreich’s ataxia ("FA") and rare cardiomyopathies (the “Acquisition”). Upon the consummation of the Acquisition, the Company acquired AavantiBio’s candidates, AVB-202-TT and AVB-401, as well as additional assets for the treatment of undisclosed cardiac diseases, platform technologies and know-how related thereto. AavantiBio is a wholly owned subsidiary of the Company.

The Company is a life sciences company focused on advancing a portfolio of neuromuscular and cardiac programs, including SGT-003, a differentiated gene therapy candidate, for the treatment of Duchenne muscular dystrophy ("Duchenne"); AVB-202-TT, a gene therapy program for the treatment of FA; AVB-401, a gene therapy program for the treatment of BAG3-mediated dilated cardiomyopathy; and additional assets for the treatment of undisclosed cardiac diseases. The Company aims to be a center of excellence, bringing together those with expertise in science, technology, disease management and care. Patient-focused and founded by those directly impacted by Duchenne, the Company's mandate is to improve the daily lives of patients living with these devastating diseases.

The Company is subject to risks and uncertainties common to early-stage companies in the biotechnology industry, including, but not limited to, development by competitors of new technological innovations, dependence on licenses, protection of proprietary technology, dependence on key personnel, compliance with government regulations and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical studies and clinical trials and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure and extensive compliance and reporting capabilities.

The Company’s candidates are in development. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s intellectual property will be obtained, that any products developed will obtain necessary government regulatory approval or that any approved products will be commercially viable. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will generate significant revenue from product sales. The Company operates in an environment of rapid change in technology and substantial competition from, among others, other pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, partners and consultants.

On October 27, 2022, the Company effected a reverse stock split of its outstanding shares of common stock at a ratio of one-for-15 pursuant to a certificate of amendment to its certificate of incorporation filed with the Secretary of State of the State of Delaware. The reverse stock split was reflected on the Nasdaq Stock Market ("Nasdaq") beginning with the opening of trading on October 28, 2022. Pursuant to the reverse stock split, every 15 shares of the Company's issued and outstanding shares of common stock were automatically combined into one issued and outstanding share of common stock, without any change in the par value per share of the common stock. The reverse stock split reduced the authorized number of shares of common stock from 300,000,000 to 20,000,000 and, pursuant to the certificate of amendment, such reduced authorized number of shares of common stock was subsequently multiplied by three, such that following the reverse stock split the Company has 60,000,000 shares of common stock authorized. The reverse stock split affected all issued and outstanding shares of the Company's common stock, and the respective numbers of shares of common stock underlying the Company’s outstanding stock options, outstanding restricted stock units, outstanding warrants and the Company's equity incentive plans were proportionately adjusted. All share and per share amounts of the common stock included in the accompanying condensed consolidated financial statements have been retrospectively adjusted to give effect to the reverse stock split for all periods presented, including reclassifying an amount equal to the reduction in par value to additional paid-in capital.

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared on a basis that assumes the Company will continue as a going concern and which contemplates the realization of assets and satisfaction of liabilities and commitments in the ordinary course of business. Through March 31, 2023, the Company has funded its operations primarily with the proceeds from the sale of redeemable preferred units and member units as well as the sale of common stock and prefunded warrants to purchase shares of its common stock in private placements and the sale of common stock in its initial public offering, follow-on public offering in March 2021 and under its at-the-market sales agreement.

On September 29, 2022, the Company entered into a securities purchase agreement, pursuant to which, on December 2, 2022, the Company issued an aggregate of 10,638,290 shares of the Company’s common stock in a private placement. The private placement closed immediately following the closing of the Acquisition on December 2, 2022. The Company received net proceeds from the private placement of $72,551.

In accordance with Accounting Standards Codification (“ASC”) 205-40, Going Concern, the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the financial statements are issued. As of March 31, 2023, the Company had an accumulated deficit of $592,808. During the three months ended March 31, 2023, the Company incurred a net loss of $30,070 and the Company used $27,995 of cash in operations. The Company expects to continue to generate operating losses in the foreseeable future. Based upon its current operating plan, the Company expects that its cash, cash equivalents and available-for-sale securities of $185,509, excluding restricted cash of $1,833, as of March 31, 2023, will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the date of issuance of these financial statements. However, the Company has based this estimate on assumptions that may prove to be wrong, and its operating plan may change as a result of many factors currently unknown to it. As a result, the Company could deplete its capital resources sooner than it currently expects. The Company expects to finance its future cash needs through a combination of equity offerings, debt financings, collaborations, strategic alliances or licensing arrangements. If the Company is unable to obtain funding, the Company would be forced to delay, reduce or eliminate some or all of its research and development programs, preclinical and clinical testing or commercialization efforts, which could adversely affect its business prospects.

The accompanying condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”). The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned or controlled subsidiaries. All intercompany accounts and transactions have been eliminated. In the opinion of management, the Company’s accompanying unaudited condensed consolidated financial statements include all adjustments, consisting of normal recurring accruals, necessary for a fair statement of the Company’s financial statements for interim periods in accordance with GAAP. The information included in this quarterly report on Form 10-Q should be read in conjunction with the Company’s consolidated financial statements and the accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2022. The year-end condensed consolidated balance sheet data presented for comparative purposes was derived from the Company’s audited financial statements but does not include all disclosures required by GAAP. The results of operations for the three months ended March 31, 2023 are not necessarily indicative of the operating results for the full year or for any other subsequent interim period.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

The Company’s accounting policies are described in the “Notes to Consolidated Financial Statements” in its Annual Report on Form 10-K for the year ended December 31, 2022 and updated, as necessary, in this report.

Use of Estimates

The preparation of the Company’s condensed consolidated financial statements in conformity with GAAP requires management to make estimates, judgments and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, estimates related to revenue recognition, the recognition of research and development expenses and equity-based compensation. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from the Company’s estimates.

The full extent to which the COVID-19 pandemic will directly or indirectly impact the Company’s business, results of operations and financial condition, including clinical trials and employee-related amounts, will depend on future developments that are highly uncertain, including new information that may emerge concerning COVID-19 and the actions taken to contain it or treat its impact. The Company has made estimates of the impact of COVID-19 within its financial statements and there may be changes to those estimates in future periods. Actual results could differ from the Company’s estimates.

Cash Equivalents

The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents.

Restricted Cash

The Company held restricted cash of $1,833 in a restricted bank account as a security deposit for a lease of the Company’s facilities as of March 31, 2023 and December 31, 2022. The Company has included restricted cash of $1,833 classified as non-current assets as of March 31, 2023 and December 31, 2022. A reconciliation of the amounts of cash and cash equivalents and restricted cash from the cash flow statement to the balance sheet is as follows:


	March 31, 2023		December 31, 2022		March 31, 2022		December 31, 2021
Cash and cash equivalents as presented on balance sheet	$	164,649	$	155,384	$	129,711	$	119,136
Restricted cash, non-current, as presented on balance sheet		1,833		1,833		2,070		2,070
Cash and cash equivalents and restricted cash as presented on cash flow statement	$	166,482	$	157,217	$	131,781	$	121,206

Leases

In June 2021, the Company entered into a lease with Hood Park LLC (“Landlord”), pursuant to which the Company leases approximately 49,869 square feet of office, laboratory, research and development and manufacturing space located in Charlestown, Massachusetts (“Premises”). The Company relocated its corporate headquarters to the Premises in June 2022. The initial term of the lease commenced in June 2022 when the construction of the lessor assets was substantially completed and continues for a ten-year period, unless earlier terminated. The lease provides the Company with an option to extend the lease for an additional five-year term. The Company and the Landlord were each obligated to undertake certain improvements prior to the commencement of the lease, and significant improvements were completed as of June 2022. The monthly lease payment is approximately $305 with annual escalation of approximately 3%. The lease includes a $10,223 construction allowance. The Company was required to post a customary letter of credit in the amount of $1,833, subject to decrease on a set schedule, as a security deposit pursuant to the lease.

During the year ended December 31, 2022, the Company recorded a failed sales-leaseback transaction related to certain lab equipment. The related financing liabilities are recorded on the Company's consolidated balance sheets within financing labilities. In connection with this transaction, the Company also recorded a cash inflow within financing activities under proceeds from financing liabilities of $2,143.

Segment Data

The Company manages its operations as a single segment for the purposes of assessing performance and making operating decisions. The Company’s singular focus is on developing treatments through gene therapy and other means for patients with neuromuscular and cardiac diseases. All of the Company’s tangible assets are held in the United States.

Related Parties

In November 2020, the Company entered into a consulting agreement with Danforth Advisors, LLC ("Danforth"), an affiliate of Stephen DiPalma, who previously served as the Company’s interim chief financial officer. Pursuant to the consulting agreement, Danforth provided the Company with the chief financial officer services of Mr. DiPalma, and other services, including financial planning, offering support and accounting services, in exchange for fees payable to Danforth based on hourly rates. The Company has paid Danforth $517 and $235 for the three months ended March 31, 2023 and 2022, respectively. In accordance with the consulting agreement, in November 2020, the Company issued to Danforth a warrant to purchase 2,000 shares of the Company’s common stock at an exercise price per share of $49.35. As of December 31, 2022, the shares had vested in full.

Collaborations

3 Months Ended

Mar. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Collaborations

3. Collaborations

Ultragenyx Collaboration

Collaboration Agreement

On October 22, 2020 (the “Effective Date”), the Company entered into the Collaboration Agreement with Ultragenyx to focus on the development and commercialization of new gene therapies for Duchenne. The Company granted Ultragenyx an exclusive worldwide license for any pharmaceutical product that expresses the Company’s proprietary microdystrophin construct from AAV8 and variants thereof in clade E for the treatment of Duchenne and other diseases resulting from the lack of functional dystrophin (the “Licensed Products”). The Company retains exclusive rights to all other uses of its microdystrophin proteins, including under its existing SGT-001 and SGT-003 programs.

The Company has conducted certain research and development activities with respect to the development of the Licensed Products, and concluded such activities as were contemplated under the Collaboration Agreement during the second quarter of 2022, resulting in the recognition of the remaining deferred revenue recorded at the time the Collaboration Agreement was executed, related to the upfront payment received from Ultragenyx. The Company may conduct additional research and development activities in collaboration with Ultragenyx from time to time in the future. Ultragenyx reimbursed the Company for personnel and out-of-pocket costs that the Company incurred in conducting such activities.

In addition, Ultragenyx granted to the Company an exclusive Development Option or Income Share Option (each as defined and described below) exercisable in the Company’s sole discretion one time per Licensed Product. After the date of first achievement of clinical proof of concept, Ultragenyx will provide to the Company a data package with respect to the relevant Licensed Product. The Company will use the data package to determine whether to exercise the corresponding Development Option or Income Share Option with respect to such Licensed Product.

With respect to each Licensed Product for which the Company has not exercised the Development Option or Income Share Option the Company will be entitled to milestone payments of up to $25,000 in the aggregate for each such Licensed Product that achieves specified development milestones and $65,000 in the aggregate for each such Licensed Product that achieves specified regulatory milestones. With respect to each Licensed Product for which the Company has not exercised the Income Share Option, the Company will also be entitled to milestone payments of up to $165,000 in the aggregate for each Licensed Product that achieves specified annual worldwide net sales milestones. For Licensed Products for which the Company has not exercised the Development Option or Income Share Option, Ultragenyx will pay the Company tiered royalties on a Licensed Product-by-Licensed Product and country-by-country basis ranging from a low double-digit percentage to a mid-teens percentage based on Ultragenyx’s annual worldwide net sales of such Licensed Products.

For each Licensed Product for which Ultragenyx decides to initiate a registrational trial in humans, the Company will have the option to fund 30% of the development costs in the United States and European Union for such Licensed Product and forgo the development and regulatory milestones (the “Development Option”) and receive tiered royalties on a Licensed Product-by-Licensed Product and country-by-country basis ranging from a mid-teens percentage to a low twenties percentage based on Ultragenyx’s annual worldwide net sales of each such Licensed Product.

For each Licensed Product for which the Company exercises the Development Option, the Company may also elect to share 30% of the net income and net losses on net sales of such Licensed Product in the United States and European Union (the “Income Share Option”). For Licensed Products for which the Company has exercised the Income Share Option, the Company will not be entitled to milestone payments and Ultragenyx will pay the Company tiered royalties on a Licensed Product-by-Licensed Product and country-by-country basis ranging from a mid-teens percentage to a low twenties percentage based on Ultragenyx’s annual net sales of each such Licensed Product outside of the United States and European Union.

The Company may only exercise an Income Share Option if neither the Company nor any of its affiliates is then developing or commercializing a product that is competitive with the Licensed Product that is subject to such option. If the Company or any of its affiliates subsequently develops or commercializes a product that is competitive with a Licensed Product for which the Company has exercised an Income Share Option, then the Company and Ultragenyx will no longer share the net income and net losses on net sales of such Licensed Product and such Licensed Product will be treated as if the Company had exercised the Development Option with respect to such Licensed Product.

Following the Company’s exercise of the Development Option or Income Share Option with respect to a Licensed Product, the Company also has the right to cease participation in the sharing of development costs and sharing in net income and net losses on net sales, as applicable, for such Licensed Product by written notice to Ultragenyx. Upon such notice, the Company will no longer share in the development costs and net income and net losses on net sales of such Licensed Product, as applicable, and will be eligible to receive payments on milestones achieved after the opt-out for such Licensed Product and royalties at the rates applicable to Licensed Products for which the Company has not exercised the Development Option or Income Share Option, as described above.

The Collaboration Agreement continues on a country-by-country and Licensed Product-by-Licensed Product basis until the expiration of all payment obligations under the agreement. With respect to any Licensed Product for which the Company has exercised an Income Share Option, the Collaboration Agreement continues until there are no longer sales of such Licensed Product in the United States or Europe. Either party has the right to terminate the agreement if the other party has materially breached in the performance of its obligations under the agreement and such breach has not been cured within the applicable cure period. Ultragenyx may also terminate the Collaboration Agreement in its sole discretion upon 90 days’ prior written notice to the Company.

Stock Purchase Agreement

In connection with the execution of the Collaboration Agreement, Ultragenyx and the Company also entered into a stock purchase agreement (the “Stock Purchase Agreement”) on the Effective Date, pursuant to which the Company issued and sold 521,719 shares of its common stock (the “Shares”) to Ultragenyx at a price of $76.6695 per share for an aggregate purchase price of approximately $40,000. The Stock Purchase Agreement contains customary representations, warranties and covenants of each of the parties thereto. Following the sale of the Shares, Ultragenyx beneficially owned approximately 14.45% of the Company’s outstanding common stock. As of March 31, 2023, Ultragenyx beneficially owned approximately 2.7% of the Company’s outstanding common stock.

Investor Agreement

In connection with the consummation of the transactions contemplated by the Stock Purchase Agreement, the Company and Ultragenyx entered into an Investor Agreement (the “Investor Agreement”) on the Effective Date. Pursuant to the terms of the Investor Agreement, Ultragenyx agreed that, so long as it holds at least 10% of the Company’s outstanding common stock, the Shares will be subject to a voting agreement, such that until the earliest to occur of certain specified events, and subject to specified conditions, Ultragenyx will, and will cause its permitted transferees to, vote in accordance with the recommendation of the Company’s Board of Directors with respect to specified matters.

Accounting Treatment

The Company concluded that the Collaboration Agreement and the Stock Purchase Agreement should be combined and treated as a single arrangement for accounting purposes as the agreements were entered into contemporaneously and in contemplation of one another.

The Company assessed this arrangement in accordance with ASC 606 and concluded that the contract counterparty, Ultragenyx, is a customer. The Company identified the following promises in the Collaboration Agreement that were evaluated under the scope of ASC 606: (1) an exclusive worldwide license to the Licensed Products; (2) an obligation to perform research and development services; and (3) an obligation to participate in a joint steering committee. The Company assessed the promised goods and services to determine if they are distinct. Based on this assessment, the Company determined that Ultragenyx cannot benefit from the promised goods and services separately from the others as they are highly interrelated and therefore not distinct. Due to the early stage of the Licensed Products, the research and development services could not be performed by another party. The Company’s skill-set, knowledge and expertise are required to conduct the research and development services and the research and development services are expected to involve significant further development of the Licensed Products. Accordingly, the promised goods and services represent one combined performance obligation and the entire transaction price will be allocated to that single combined performance obligation.

The Company determined the transaction price under ASC 606 at the inception of the Collaboration Agreement to be $22,513, which represents the excess proceeds from the equity investment under the Stock Purchase Agreement, when measured at fair value after taking into consideration a discount for lack of marketability, plus the estimated reimbursement of research and development costs, which represents variable consideration. The Company included the estimated reimbursement of research and development costs in the transaction price at the inception of the arrangement because the Company is required to perform research and development services and the contract requires Ultragenyx to reimburse the Company for costs incurred. Also, since the related revenue would be recognized only as the costs are incurred, the Company determined it is not probable that a significant reversal of cumulative revenue would occur. The Company evaluated how much variable consideration related to development and regulatory milestones, and the Company’s potential exercise of its Development Option or Income Share Option per Licensed Product, to include in the transaction price using the most likely amount approach and concluded that no amount should be included in the transaction price due to the high degree of uncertainty and risk associated with these potential payments. The Company also determined that royalties and sales milestones relate solely to the license of intellectual property and are therefore excluded from the transaction price under the sales- or usage-based royalty exception of ASC 606. Revenue related to these royalties and sales milestones will only be recognized when the associated sales occur, and relevant thresholds are met.

The Company determined that revenue under the Collaboration Agreement should be recognized over time as Ultragenyx simultaneously receives the benefit from the Company as the Company performs under the single performance obligation over time. The Company will recognize revenue for the single performance obligation using a cost-to-cost input method as the Company has concluded it best depicts the research and development and joint steering committee participation services performed. Under this method, the transaction price is recognized over the contract’s entire performance period, using costs incurred relative to total estimated costs to determine the extent of progress towards completion.

During the three months ended March 31, 2023 and March 31, 2022, the Company recognized $0 and $1,925 of related party collaboration revenue, respectively, associated with its collaboration with Ultragenyx related to research and development services performed during the period and the corresponding cost reimbursement receivable.

As of March 31, 2023 and December 31, 2022, there was $0 of deferred revenue related to the Collaboration Agreement. Additionally, as of March 31, 2023 and December 31, 2022, there was $0 of related party collaboration receivables related to reimbursable costs expected to be received from Ultragenyx for research and development services performed.

Costs incurred relating to the Collaboration Agreement consist of internal and external research and development costs, which primarily include salaries and benefits, lab supplies, preclinical research studies, clinical studies, consulting services, and commercial development. These costs are included in research and development expenses in the Company’s condensed consolidated statement of operations during the three months ended March 31, 2023 and three months ended March 31, 2022.

Acquisition

3 Months Ended

Mar. 31, 2023

Business Combinations [Abstract]

Acquisition

4. Acquisition

On September 29, 2022, the Company entered into an Agreement and Plan of Merger with AavantiBio. The Acquisition closed on December 2, 2022 and was announced on December 5, 2022. This acquisition allowed the Company to add to its pipeline of assets. The Company acquired AavantiBio for a total purchase price of $9,169, including (i) $1 in cash and (ii) 1,354,258 shares of its common stock, par value $0.001 per share, with a fair value of $9,168 to AavantiBio equityholders. The price per share of the Company’s common stock used in the calculation of the purchase price is based on the closing price of Solid’s common stock on the Nasdaq Global Select Market on December 2, 2022, which was $6.77.

The Acquisition was accounted for as a business combination in which the Company, as the accounting acquirer, recorded the assets acquired and liabilities assumed from AavantiBio at their fair values as of the acquisition date. The Company recognized a gain on the purchase of AavantiBio of $18,236 as the net assets acquired of $27,405 were greater than the purchase price of $9,169. Prior to recognizing the gain, the Company reassessed the measurement and recognition of identifiable assets acquired, and liabilities assumed and concluded that the valuation procedures and resulting measures were appropriate, in all material respects. The Company believes that its ability to negotiate a purchase price lower than the fair market value of the acquired net assets was due to a combination of factors, including the then prevailing market conditions and the uncertain future macroeconomic environment. The Company believes the seller, as a smaller, less well capitalized company, was motivated to complete the transaction under the terms described above as growing economic uncertainty and a rising interest rate environment negatively impacted their ability to raise additional capital.

The Company incurred acquisition related costs of $0 for three months ended March 31, 2023.

The fair value was determined utilizing the fair value hierarchy as described in Note 2 and Note 5 to our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2022.

The following table summarizes the fair values of the assets acquired and liabilities assumed from AavantiBio at the acquisition date.


	December 2, 2022
Assets
Current assets:
Cash and cash equivalents	$	31,524
Prepaid expenses and other current assets		403
Total current assets		31,927
Operating lease, right-of-use asset		1,027
Property and equipment		2,765
Other non-current assets		23
Total assets	$	35,742
Liabilities
Current liabilities:
Accounts payable	$	3,575
Accrued expenses		3,634
Operating lease liabilities		778
Total current liabilities		7,987
Operating lease liabilities, excluding current portion		350
Total liabilities		8,337
Net assets acquired		27,405
Total consideration paid		9,169
Gain on acquisition of business	$	18,236

For the period from December 3, 2022 to December 31, 2022, AavantiBio's revenue and net loss before taxes included within the consolidated statement of operations subsequent to the closing of the Acquisition was $0 and $6,041, respectively.

Fair Value of Financial Assets and Liabilities

3 Months Ended

Mar. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value of Financial Assets and Liabilities

5. Fair Value of Financial Assets and Liabilities

The following tables present information about the Company’s assets and liabilities that are measured at fair value on a recurring basis and indicate the level of the fair value hierarchy utilized to determine such fair values:


	Fair Value Measurements as of March 31, 2023 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	—	$	110,937	$	—	$	110,937
Available-for-sale securities		—		20,860		—		20,860
	$	—	$	131,797	$	—	$	131,797


	Fair Value Measurements as of December 31, 2022 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	—	$	69,374	$	—	$	69,374
Available-for-sale securities		—		58,338		—		58,338
	$	—	$	127,712	$	—	$	127,712

As of March 31, 2023 and December 31, 2022, the fair values of the Company’s cash equivalents and available-for-sale securities were determined using Level 2 inputs. During the three months ended March 31, 2023 and the year ended December 31, 2022, there were no transfers between Level 1, Level 2 and Level 3.

The fair value of the Company’s cash, restricted cash, accounts payable, and accrued expenses and other current liabilities approximate their carrying value due to their short-term maturities.

Available-for-Sale Securities

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Available-for-Sale Securities

6. Available-for-Sale Securities

As of March 31, 2023, the fair value of available-for-sale securities by type of security was as follows:


	March 31, 2023
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments:
Treasury bills	$	19,989	$	5	$	—	$	19,994
Corporate bond securities		866		—		—		866
	$	20,855	$	5	$	—	$	20,860

As of December 31, 2022, the fair value of available-for-sale securities by type of security was as follows:


	December 31, 2022
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Treasury bill	$	34,780	$	—	$	(30	)	$	34,750
Corporate bond securities		23,626		—		(38	)		23,588
	$	58,406	$	—	$	(68	)	$	58,338

The estimated fair value and amortized cost of the Company’s available-for-sale securities as of March 31, 2023 by contractual maturity are summarized as follows:


	March 31, 2023
	Amortized Cost		Fair Value
Due in one year or less	$	20,855	$	20,860
Total available-for-sale securities	$	20,855	$	20,860

The weighted average maturity of the Company’s available-for-sale securities as of March 31, 2023 was approximately 0.5 years.

The estimated fair value and amortized cost of the Company’s available-for-sale securities as of December 31, 2022 by contractual maturity are summarized as follows:


	December 31, 2022
	Amortized Cost		Fair Value
Due in one year or less	$	58,406	$	58,338
Total available-for-sale securities	$	58,406	$	58,338

The weighted average maturity of the Company’s available-for-sale securities as of December 31, 2022 was approximately 0.5 years.

Property and Equipment

3 Months Ended

Mar. 31, 2023

Property, Plant and Equipment [Abstract]

Property and Equipment

7. Property and Equipment

Property and equipment consists of the following:


	March 31, 2023		December 31, 2022
Furniture and fixtures	$	936	$	868
Laboratory equipment		15,372		16,416
Leasehold improvements		440		384
Computer equipment		677		677
Computer software		553		553
Construction in process		1,486		1,715
		19,464		20,613
Less accumulated depreciation		10,857		10,956
	$	8,607	$	9,657

Depreciation expense was $703 and $709 for the three months ended March 31, 2023 and 2022, respectively. During the three months ended March 31, 2023 and 2022, the Company recognized an impairment loss of $374 and $0, respectively.

Prepaid Expenses and Other Current Assets

3 Months Ended

Mar. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Prepaid Expenses and Other Current Assets

8. Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following:


	March 31, 2023		December 31, 2022
Prepaid research and development expenses	$	2,245	$	2,913
Prepaid expenses and other assets		2,850		3,003
	$	5,095	$	5,916

Accrued Expenses and Other Current Liabilities

3 Months Ended

Mar. 31, 2023

Payables and Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

9. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


	March 31, 2023		December 31, 2022
Accrued research and development	$	6,109	$	3,033
Accrued compensation		3,822		8,370
Accrued other		2,453		5,288
	$	12,384	$	16,691

Stockholders' Equity

3 Months Ended

Mar. 31, 2023

Equity [Abstract]

Stockholders' Equity

10. Stockholders’ Equity

In July 2019, the Company issued and sold in a private placement (i) 707,168 shares of its common stock at a price per share of $69.75 and (ii) 153,046 pre-funded warrants to purchase shares of its common stock at a price per warrant of $69.60. Each pre-funded warrant was exercisable for one share of common stock at an exercise price of $0.15 and the pre-funded warrants had no expiration date. In October 2020, 9,158 of these pre-funded warrants were exercised. As of December 31, 2022, there were no pre-funded warrants outstanding.

In March 2021, the Company issued and sold in a public offering 1,666,666 shares of its common stock at a price to the public of $83.63 per share. The Company received net proceeds of $134,878 after deducting underwriting discounts and commissions and offering expenses.

On December 2, 2022, the Company issued and sold 10,638,290 shares of its common stock at a price per share of $7.05 in a private placement, which closed immediately following the Acquisition. The Company received net proceeds of $72,551 after deducting offering costs.

- Definition

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

+ References

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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Paragraph 14
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 505
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-Paragraph 13
-Subparagraph (i)
-URI https://asc.fasb.org/extlink&oid=126973232&loc=SL123496158-112644

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126731327&loc=SL126733271-114008

+ Details

Equity-Based Compensation

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Equity-Based Compensation

11. Equity-Based Compensation

In connection with the closing of the Company’s initial public offering, the Board of Directors and stockholders approved the 2018 Omnibus Incentive Plan (the “2018 Plan”), which provides for the reservation of 333,400 shares of common stock for equity awards. On June 16, 2020, the Company’s stockholders approved the 2020 Equity Incentive Plan (as amended or restated, the “2020 Plan”) which consisted of, at the time of approval (i) 200,000 shares of common stock and (ii) additional shares of common stock (up to 325,268) as is equal to (i) the number of shares reserved under the 2018 Plan that remain available for grant under the 2018 Plan as of immediately prior to the date the 2020 Plan was approved by the Company’s stockholders and (ii) the number of shares subject to awards granted under the 2018 Plan which awards expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by the Company at their original issuance price pursuant to a contractual repurchase right. As of the effective date of the 2020 Plan, no further awards will be made under the 2018 Plan. Any options or awards outstanding under the 2018 Plan remain outstanding and effective and are governed by their existing terms. In June 2021, the Company’s stockholders approved an amendment to the 2020 Plan to reserve an additional 466,666 shares of common stock for issuance under the plan. On December 1, 2022, the Company's stockholders approved an amendment and restatement of the 2020 Plan to (i) increase the number of shares of common stock reserved for issuance under the plan by 866,666 shares to 1,533,333 shares, subject to adjustment in the event of stock splits and other similar events, (ii) provide for an annual increase, to be added on the first day of each fiscal year during the term of the plan, beginning with the fiscal year ending December 31, 2023, of 5% of the number of shares of common stock outstanding on the first day of such fiscal year or a lesser number of shares determined by the Board of Directors, (iii) provide that up to 1,858,601 shares of common stock may be granted as “incentive stock options” under the 2020 Plan, (iv) extend the term of the plan to December 1, 2032 and (v) revise certain provisions of the plan relating to the Board of Director’s ability to delegate authority to make awards under the plan. Under the 2020 Plan, stock options may not be granted at less than fair value on the date of grant. As of March 31, 2023, 137,662 shares remained available for future issuance under the 2020 Plan. Under the 2020 Plan, stock options may not be granted at less than fair value on the date of grant.

In June 2021, the Company's stockholders also approved the 2021 Employee Stock Purchase Plan (“ESPP”), which provides for 73,525 shares to be available for purchase by eligible employees according to its terms. The first offering period under the ESPP commenced on September 1, 2021. As of March 31, 2023, 41,417 shares remained available for future issuance under the ESPP.

During the three months ended March 31, 2023, the Company granted options to purchase 695,596 shares of common stock under the 2020 Plan and options to purchase 90,000 shares of common stock as an inducement award in accordance with Nasdaq Listing Rule 5635(c)(4). During the three months ended March 31, 2022, the Company granted options to purchase 174,738 shares of common stock. During the three months ended March 31, 2023, the Company granted 347,997 restricted stock units under the 2020 Plan and 45,000 restricted stock units as an inducement award in accordance with Nasdaq Listing Rule 5635(c)(4). During the three months ended March 31, 2022, the Company granted 96,766 restricted stock units.

The Company recorded equity-based compensation expense related to all of its share-based awards to employees and non-employees in the following captions within its condensed consolidated statements of operations:


	Three Months Ended March 31,
	2023		2022
Research and development	$	898	$	1,180
General and administrative		1,220		1,432
Total	$	2,118	$	2,612

Income Taxes

3 Months Ended

Mar. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

12. Income Taxes

During the three months ended March 31, 2023 and 2022, the Company recorded no income tax benefits for the net operating losses incurred or for the research and development tax credits and orphan drug credits generated in each year due to its uncertainty of realizing a benefit from those items. The Company has provided a valuation allowance for the full amount of its net deferred tax assets because, at March 31, 2023 and December 31, 2022, it was more likely than not that any future benefit from deductible temporary differences and net operating loss and tax credit carryforwards would not be realized.

As of March 31, 2023 and December 31, 2022, the Company had not recorded any amounts for unrecognized tax benefits. The Company files income tax returns as prescribed by the tax laws of the jurisdictions in which it operates. In the normal course of business, the Company is subject to examination by federal and state jurisdictions, where applicable. There are currently no pending income tax examinations. The Company’s C-Corporation tax years beginning with the year ended December 31, 2019 are open under statute. Any tax credit or net operating loss carryforward can be adjusted in future periods after the respective year of generation’s statute of limitation has closed.

- 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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330215-122817

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 17
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32809-109319

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I.5.Q1)
-URI https://asc.fasb.org/extlink&oid=122134291&loc=d3e330036-122817

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 14
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32705-109319

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 270
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=6424409&loc=d3e44925-109338

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-URI https://asc.fasb.org/topic&trid=2144680

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 30
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=6424122&loc=d3e41874-109331

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Commitments and Contingencies

3 Months Ended

Mar. 31, 2023

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

13. Commitments and Contingencies

Letter of Credit

The Company had an outstanding letter of credit in the amount of $1,833 at March 31, 2023 and December 31, 2022, which was required as a condition of the Company’s office and laboratory leases.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters, including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with its executive officers and members of its Board of Directors that require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as executive officers or directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnification arrangements.

The Company does not believe that the outcome of any claims under indemnification arrangements will have a material effect on its financial position, results of operations or cash flows, and it has not accrued any liabilities related to such obligations in its consolidated financial statements as of March 31, 2023 and December 31, 2022.

Legal Proceedings

The Company may periodically become subject to legal proceedings and claims arising in connection with ongoing business activities, including claims or disputes related to patents that have been issued or that are pending in the field of research on which the Company is focused. The Company is not aware of any material legal proceedings or claims as of March 31, 2023.

Net Loss per Share

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Net Loss per Share

14. Net Loss per Share

Basic and diluted net loss per share attributable to common stockholders were calculated as follows:

The numerator for basic and diluted net loss per share attributable to common stockholders is as follows:


	Three Months Ended March 31,
	2023			2022
Net loss attributable to common stockholders	$	(30,070	)	$	(25,328	)

The denominator is as follows:


	Three Months Ended March 31,
	2023		2022
Weighted average shares of common stock outstanding, basic and diluted		19,567,635		7,507,155

Net loss per share attributable to common stockholders, basic and diluted is as follows:


	Three Months Ended March 31,
	2023			2022
Net loss per share attributable to common stockholders	$	(1.54	)	$	(3.37	)

The following potential common stock equivalents, presented based on amounts outstanding at each period end, were excluded from the calculation of diluted net loss per share attributable to common stockholders for the periods indicated because including them would have had an anti-dilutive effect for the three and three months ended March 31:


	2023		2022
Options to purchase shares of common stock		2,113,510		1,433,968
Unvested restricted stock units		841,570		512,557
		2,955,080		1,946,525

Restructuring

3 Months Ended

Mar. 31, 2023

Restructuring and Related Activities [Abstract]

Restructuring

15. Restructuring

April 2022 Plan

In April 2022, the Company implemented changes to its corporate strategy to prioritize the advancement of its then-key programs, SGT-001 and SGT-003. In connection with the changes to corporate operations, the Company reduced headcount by approximately 35 percent. During the year ended December 31, 2022, the Company recorded and paid aggregate restructuring charges of $1,520 related to severance and other employee related costs in connection with the changes to its corporate strategy. The Company does not expect to incur any additional significant costs associated with this restructuring.

November 2022 Plan

In November 2022, the Company’s Board of Directors approved a plan to reduce the Company’s workforce by approximately 18 percent. These reductions were completed by December 5, 2022. This plan was designed to streamline the Company’s operating structure following the Acquisition. The Company recorded a restructuring charge in the fourth quarter of 2022 of $5,658 related to the reduction in force, consisting of severance and other employee termination benefits. The Company paid $2,348 of this amount during the three months ended March 31, 2023 and $1,737 during the year ended December 31, 2022. The Company expects that approximately the remaining $1,573 will be paid by the first quarter of 2024.


One-Time Employee Termination Benefits	April 2022			November 2022
Accrued restructuring charges as of December 31, 2021	$	—		$	—
Accrual recorded as a result of restructuring charges		1,520			5,658
Amounts paid during the period		(1,520	)		(1,737	)
Accrued restructuring charges as of December 31, 2022	$	—		$	3,921
Accrual recorded as a result of restructuring charges		—			—
Amounts paid during the period		—			(2,348	)
Accrued restructuring charges as of March 31, 2023	$	—		$	1,573

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2023

Accounting Policies [Abstract]

Use of Estimates

Cash Equivalents

The Company considers all short-term, highly liquid investments with original maturities of 90 days or less at acquisition date to be cash equivalents.

Restricted Cash


	March 31, 2023		December 31, 2022		March 31, 2022		December 31, 2021
Cash and cash equivalents as presented on balance sheet	$	164,649	$	155,384	$	129,711	$	119,136
Restricted cash, non-current, as presented on balance sheet		1,833		1,833		2,070		2,070
Cash and cash equivalents and restricted cash as presented on cash flow statement	$	166,482	$	157,217	$	131,781	$	121,206

Leases

Segment Data

Related Parties

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2023

Accounting Policies [Abstract]

Reconciliation of Amounts From Cash Flow Statement to Balance Sheet

A reconciliation of the amounts of cash and cash equivalents and restricted cash from the cash flow statement to the balance sheet is as follows:


	March 31, 2023		December 31, 2022		March 31, 2022		December 31, 2021
Cash and cash equivalents as presented on balance sheet	$	164,649	$	155,384	$	129,711	$	119,136
Restricted cash, non-current, as presented on balance sheet		1,833		1,833		2,070		2,070
Cash and cash equivalents and restricted cash as presented on cash flow statement	$	166,482	$	157,217	$	131,781	$	121,206

Acquisition (Tables)

3 Months Ended

Mar. 31, 2023

Business Combinations [Abstract]

Summary of Fair Values of Assets Acquired and Liabilities Assumed

The following table summarizes the fair values of the assets acquired and liabilities assumed from AavantiBio at the acquisition date.


	December 2, 2022
Assets
Current assets:
Cash and cash equivalents	$	31,524
Prepaid expenses and other current assets		403
Total current assets		31,927
Operating lease, right-of-use asset		1,027
Property and equipment		2,765
Other non-current assets		23
Total assets	$	35,742
Liabilities
Current liabilities:
Accounts payable	$	3,575
Accrued expenses		3,634
Operating lease liabilities		778
Total current liabilities		7,987
Operating lease liabilities, excluding current portion		350
Total liabilities		8,337
Net assets acquired		27,405
Total consideration paid		9,169
Gain on acquisition of business	$	18,236

Fair Value of Financial Assets and Liabilities (Tables)

3 Months Ended

Mar. 31, 2023

Fair Value Disclosures [Abstract]

Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis and Indicate Level of Fair Value Hierarchy Utilized


	Fair Value Measurements as of March 31, 2023 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	—	$	110,937	$	—	$	110,937
Available-for-sale securities		—		20,860		—		20,860
	$	—	$	131,797	$	—	$	131,797


	Fair Value Measurements as of December 31, 2022 Using:
	Level 1		Level 2		Level 3		Total
Assets:
Cash equivalents	$	—	$	69,374	$	—	$	69,374
Available-for-sale securities		—		58,338		—		58,338
	$	—	$	127,712	$	—	$	127,712

Available-for-Sale Securities (Tables)

3 Months Ended

Mar. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Fair Value of Available-for-Sale Securities by Type of Security

As of March 31, 2023, the fair value of available-for-sale securities by type of security was as follows:


	March 31, 2023
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Fair Value
Investments:
Treasury bills	$	19,989	$	5	$	—	$	19,994
Corporate bond securities		866		—		—		866
	$	20,855	$	5	$	—	$	20,860

As of December 31, 2022, the fair value of available-for-sale securities by type of security was as follows:


	December 31, 2022
	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Fair Value
Investments:
Treasury bill	$	34,780	$	—	$	(30	)	$	34,750
Corporate bond securities		23,626		—		(38	)		23,588
	$	58,406	$	—	$	(68	)	$	58,338

Summary Estimated Fair Value and Amortized Cost of Available-for-Sale Securities by Contractual Maturity

The estimated fair value and amortized cost of the Company’s available-for-sale securities as of March 31, 2023 by contractual maturity are summarized as follows:


	March 31, 2023
	Amortized Cost		Fair Value
Due in one year or less	$	20,855	$	20,860
Total available-for-sale securities	$	20,855	$	20,860

The estimated fair value and amortized cost of the Company’s available-for-sale securities as of December 31, 2022 by contractual maturity are summarized as follows:


	December 31, 2022
	Amortized Cost		Fair Value
Due in one year or less	$	58,406	$	58,338
Total available-for-sale securities	$	58,406	$	58,338

Property and Equipment (Tables)

3 Months Ended

Mar. 31, 2023

Property, Plant and Equipment [Abstract]

Summary of Property and Equipment

Property and equipment consists of the following:


	March 31, 2023		December 31, 2022
Furniture and fixtures	$	936	$	868
Laboratory equipment		15,372		16,416
Leasehold improvements		440		384
Computer equipment		677		677
Computer software		553		553
Construction in process		1,486		1,715
		19,464		20,613
Less accumulated depreciation		10,857		10,956
	$	8,607	$	9,657

Prepaid Expenses and Other Current Assets (Tables)

3 Months Ended

Mar. 31, 2023

Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consist of the following:


	March 31, 2023		December 31, 2022
Prepaid research and development expenses	$	2,245	$	2,913
Prepaid expenses and other assets		2,850		3,003
	$	5,095	$	5,916

Accrued Expenses and Other Current Liabilities (Tables)

3 Months Ended

Mar. 31, 2023

Payables and Accruals [Abstract]

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consist of the following:


	March 31, 2023		December 31, 2022
Accrued research and development	$	6,109	$	3,033
Accrued compensation		3,822		8,370
Accrued other		2,453		5,288
	$	12,384	$	16,691

Equity-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2023

Share-Based Payment Arrangement [Abstract]

Schedule of Equity-based Compensation Expense


	Three Months Ended March 31,
	2023		2022
Research and development	$	898	$	1,180
General and administrative		1,220		1,432
Total	$	2,118	$	2,612

Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2023

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Loss per Share Attributable to Common Stockholders

The numerator for basic and diluted net loss per share attributable to common stockholders is as follows:


	Three Months Ended March 31,
	2023			2022
Net loss attributable to common stockholders	$	(30,070	)	$	(25,328	)

The denominator is as follows:


	Three Months Ended March 31,
	2023		2022
Weighted average shares of common stock outstanding, basic and diluted		19,567,635		7,507,155

Net loss per share attributable to common stockholders, basic and diluted is as follows:


	Three Months Ended March 31,
	2023			2022
Net loss per share attributable to common stockholders	$	(1.54	)	$	(3.37	)

Schedule of Antidilutive Securities Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders


	2023		2022
Options to purchase shares of common stock		2,113,510		1,433,968
Unvested restricted stock units		841,570		512,557
		2,955,080		1,946,525

Restructuring (Tables)

3 Months Ended

Mar. 31, 2023

Restructuring and Related Activities [Abstract]

Schedule of Accrued Restructuring Charges


One-Time Employee Termination Benefits	April 2022			November 2022
Accrued restructuring charges as of December 31, 2021	$	—		$	—
Accrual recorded as a result of restructuring charges		1,520			5,658
Amounts paid during the period		(1,520	)		(1,737	)
Accrued restructuring charges as of December 31, 2022	$	—		$	3,921
Accrual recorded as a result of restructuring charges		—			—
Amounts paid during the period		—			(2,348	)
Accrued restructuring charges as of March 31, 2023	$	—		$	1,573

Nature of the Business and Basis of Presentation - Additional Information (Detail) $ in Thousands			3 Months Ended
	Dec. 02, 2022 USD ($) shares	Oct. 27, 2022 shares	Mar. 31, 2023 USD ($) shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) shares	Oct. 28, 2022 shares	Jun. 30, 2022 shares
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net loss			$ 30,070	$ 25,328
Accumulated deficit			592,808		$ 562,738
Net cash used in operating activities			27,995	$ 27,190
Cash, cash equivalents and available-for-sale securities			$ 185,509
Reverse stock split of outstanding shares of common stock		one-for-15
Stockholders' equity note, stock split, conversion ratio		0.015
Common stock, shares authorized \| shares		20,000,000	60,000,000		60,000,000	60,000,000	300,000,000
Restricted cash			$ 1,833
Securities Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Net proceeds from private placement	$ 72,551
Common Stock [Member] \| Securities Purchase Agreement [Member]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Common stock shares issued \| shares	10,638,290

Summary of Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended
	Jun. 30, 2021 USD ($) ft²	Mar. 31, 2023 USD ($) shares	Mar. 31, 2022 USD ($)	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Nov. 30, 2020 $ / shares shares
Significant Accounting Policies [Line Items]
Restricted cash deposit		$ 1,833		$ 1,833
Restricted cash noncurrent		1,833	$ 2,070	$ 1,833	$ 2,070
Proceeds from financing liabilities		$ 2,143
Common stock, shares issued \| shares		19,573,132		19,556,732
Payment of exchange fees		$ 517	$ 235
Common stock shares issued warrant to purchase \| shares						2,000
Common stock warrants exercise price per share \| $ / shares						$ 49.35
Office laboratory [Member] \| Hood Park LLC [Member]
Significant Accounting Policies [Line Items]
Area of lease agreement \| ft²	49,869
Lease description		The Company relocated its corporate headquarters to the Premises in June 2022. The initial term of the lease commenced in June 2022 when the construction of the lessor assets was substantially completed and continues for a ten-year period, unless earlier terminated. The lease provides the Company with an option to extend the lease for an additional five-year term. The Company and the Landlord were each obligated to undertake certain improvements prior to the commencement of the lease, and significant improvements were completed as of June 2022.
Operating lease, monthly payments	$ 305
Operating lease payments annual escalation percentage	3.00%
Construction allowance	$ 10,223
Letter of credit amount		$ 1,833

Summary of Significant Accounting Policies - Reconciliation of Amounts From Cash Flow Statement to Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Reconciliation Of Beginning And End Of Period Amounts From Cash Flow Statement To Balance Sheet [Abstract]
Cash and cash equivalents as presented on balance sheet	$ 164,649	$ 155,384	$ 129,711	$ 119,136
Restricted cash, non-current, as presented on balance sheet	1,833	1,833	2,070	2,070
Cash and cash equivalents and restricted cash as presented on cash flow statement	$ 166,482	$ 157,217	$ 131,781	$ 121,206

Collaborations - Additional Information (Detail) - USD ($)		3 Months Ended		9 Months Ended	12 Months Ended
	Oct. 22, 2020	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022	Dec. 31, 2022
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Related party revenue recognized			$ 1,925,000
Ultragenyx [Member] \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of regulatory milestone		$ 65,000,000
Percentage of option to fund of development cost		30.00%
Percentage of net income and net losses on net sales		30.00%
Agreement termination notice period		90 days
Issued and sold shares of common stock	521,719
Common stock issued price per share	$ 76.6695
Proceeds from issuance of common stock, net of issuance costs	$ 40,000,000
Percentage of outstanding common stock	14.45%	2.70%
Transaction price determined under ASC 606		$ 22,513,000
Transaction price		0
Related party revenue recognized		0	$ 1,925,000		$ 0
Deferred revenue - related party		0			$ 0
Ultragenyx [Member] \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Milestone payments upon achievement of development milestone		25,000,000
Milestone Payments upon achievement of net sales milestones		$ 165,000,000
Ultragenyx [Member] \| Collaborative Arrangement, Transaction with Party to Collaborative Arrangement [Member] \| Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of outstanding common stock				10.00%

Acquisition - Additional Information (Detail) - AavantiBio, Inc [Member] - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended
	Dec. 02, 2022	Dec. 31, 2022	Mar. 31, 2023
Business Acquisition [Line Items]
Business acquisition, effective date of acquisition	Sep. 29, 2022
Business acquisition, Acquisition completion date	Dec. 02, 2022
Total purchase price	$ 9,169
Cash payment	$ 1
Number of shares of common stock	1,354,258
Business acquisition, share price	$ 0.001
Business Acquisition, fair value	$ 9,168
Gain on acquisition	18,236
Acquisition related costs			$ 0
Net assets acquired	$ 27,405
Revenues		$ 0
Net loss before taxes		$ 6,041
Common Stock [Member]
Business Acquisition [Line Items]
Business acquisition, share price	$ 6.77
Minimum [Member]
Business Acquisition [Line Items]
Total purchase price	$ 9,169

Acquisition - Summary of Fair Values of Assets Acquired and Liabilities Assumed (Detail) - AavantiBio, Inc [Member] $ in Thousands	Dec. 02, 2022 USD ($)
Current assets:
Cash and cash equivalents	$ 31,524
Prepaid expenses and other current assets	403
Total current assets	31,927
Operating lease, right-of-use asset	1,027
Property and equipment	2,765
Other non-current assets	23
Total assets	35,742
Current liabilities:
Accounts payable	3,575
Accrued expenses	3,634
Operating lease liabilities	778
Total current liabilities	7,987
Operating lease liabilities, excluding current portion	350
Total liabilities	8,337
Net assets acquired	27,405
Total consideration paid	9,169
Gain on acquisition of business	$ 18,236

Acquisition - Summary of Unaudited Proforma Information (Detail) $ in Thousands	1 Months Ended
	Dec. 31, 2022 USD ($)
AavantiBio, Inc [Member]
Business Acquisition [Line Items]
Revenues	$ 0

Fair Value of Financial Assets and Liabilities - Summary of Assets and Liabilities Measured at Fair Value on Recurring Basis and Indicate Level of Fair Value Hierarchy Utilized (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Cash equivalents	$ 110,937	$ 69,374
Available-for-sale securities	20,860	58,338
Assets Fair Value Disclosure	131,797	127,712
Level 2 [Member]
Assets:
Cash equivalents	110,937	69,374
Available-for-sale securities	20,860	58,338
Assets Fair Value Disclosure	$ 131,797	$ 127,712

Fair Value of Financial Assets and Liabilities - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Fair Value Disclosures [Abstract]
Fair value, assets, transfers into level 3, amount	$ 0	$ 0
Fair value, assets, transfers out of level 3, amount	0	0
Fair value, assets, transfers into level 2, amount	0	0
Fair value, assets, transfers out of level 2, amount	0	0
Fair value, assets, transfers into level 1, amount	0	0
Fair value, assets, transfers out of level 1, amount	$ 0	$ 0

Available-for-Sale Securities - Schedule of Fair Value of Available-for-Sale Securities by Type of Security (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	$ 20,855	$ 58,406
Gross Unrealized Gain	5
Gross Unrealized Loss		(68)
Fair Value	20,860	58,338
Treasury Bills [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	19,989	34,780
Gross Unrealized Gain	5
Gross Unrealized Loss		(30)
Fair Value	19,994	34,750
Corporate Bond Securities [Member]
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	866	23,626
Gross Unrealized Loss		(38)
Fair Value	$ 866	$ 23,588

Available-for-Sale Securities - Summary Estimated Fair Value and Amortized Cost of Available-for-Sale Securities by Contractual Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Due in one year or less, amortized cost	$ 20,855	$ 58,406
Amortized Cost	20,855	58,406
Due in one year or less, fair value	20,860	58,338
Total available-for-sale securities, fair value	$ 20,860	$ 58,338

Available-for-Sale Securities - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
Investments, Debt and Equity Securities [Abstract]
Available-for-sale securities average maturity period	6 months	6 months

Property and Equipment - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 19,464	$ 20,613
Less accumulated depreciation	10,857	10,956
Property and equipment, net	8,607	9,657
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	936	868
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	15,372	16,416
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	440	384
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	677	677
Computer Software [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	553	553
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,486	$ 1,715

Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 703	$ 709
Impairment loss	$ 374	$ 0

Prepaid Expenses and Other Current Assets - Schedule of Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Prepaid research and development expenses	$ 2,245	$ 2,913
Prepaid expenses and other assets	2,850	3,003
Prepaid expenses and other current assets	$ 5,095	$ 5,916

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Accrued Expenses And Other Current Liabilities [Line Items]
Accrued expenses and other current liabilities	$ 12,384	$ 16,691
Accrued Research and Development [Member]
Accrued Expenses And Other Current Liabilities [Line Items]
Accrued expenses and other current liabilities	6,109	3,033
Accrued Compensation [Member]
Accrued Expenses And Other Current Liabilities [Line Items]
Accrued expenses and other current liabilities	3,822	8,370
Accrued Other [Member]
Accrued Expenses And Other Current Liabilities [Line Items]
Accrued expenses and other current liabilities	$ 2,453	$ 5,288

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended
	Dec. 02, 2022	Mar. 31, 2021	Oct. 31, 2020	Jul. 31, 2019	Dec. 31, 2022	Nov. 30, 2020
Class Of Stock [Line Items]
Common stock warrants exercise price per share						$ 49.35
Public Offering [Member]
Class Of Stock [Line Items]
Stock issued and sold		1,666,666
Common stock issued price per share		$ 83.63
Proceeds from issuance of common stock, net of issuance costs		$ 134,878
Common Stock [Member] \| Private Placement [Member]
Class Of Stock [Line Items]
Stock issued and sold	10,638,290			707,168
Common stock issued price per share	$ 7.05			$ 69.75
Company received net proceeds	$ 72,551
Pre-Funded Warrants [Member]
Class Of Stock [Line Items]
Warrants exercised			9,158
Warrants outstanding					0
Pre-Funded Warrants [Member] \| Private Placement [Member]
Class Of Stock [Line Items]
Warrants to purchase common stock				153,046
Warrants price per share				$ 69.60
Warrants exercisable for common stock				1
Common stock warrants exercise price per share				$ 0.15

Equity-Based Compensation - Additional Information (Detail) - shares		1 Months Ended	3 Months Ended
	Jun. 16, 2020	Jun. 30, 2021	Mar. 31, 2023	Mar. 31, 2022	Dec. 01, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchased				174,738
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock units granted				96,766
Inducement Award [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock purchased			90,000
Restricted stock units granted			45,000
Incentive Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for future issuance					1,858,601
2018 Omnibus Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for common stock for equity awards			333,400
2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for common stock for equity awards	200,000
Number of additional shares authorized for common stock for equity awards		466,666
Number of shares available for future issuance			137,662
Common stock purchased			695,596
Restricted stock units granted			347,997
2020 Equity Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized for common stock for equity awards	325,268
2021 Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized for common stock for equity awards		73,525
Number of shares available for future issuance			41,417
Amended and Restated 2020 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of additional shares authorized for common stock for equity awards			866,666
Number of share reserved for future issuance					1,533,333
Percentage of number of shares outstanding			5.00%

Equity-Based Compensation - Schedule of Equity-based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,118	$ 2,612
Research and Development [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	898	1,180
General and Administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 1,220	$ 1,432

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Income Tax Disclosure [Abstract]
Income tax expense (benefit)	$ 0	$ 0
Unrecognized tax benefits	$ 0		$ 0

- Definition

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References + Details

Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Office and Laboratory Lease [Member]
Commitment And Contingencies [Line Items]
Letter of credit outstanding amount	$ 1,833	$ 1,833

Net Loss per Share - Schedule of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share Basic [Line Items]
Net loss attributable to common stockholders	$ (30,070)	$ (25,328)
Weighted average shares of common stock outstanding, basic	19,567,635	7,507,155
Weighted average shares of common stock outstanding, diluted	19,567,635	7,507,155
Net loss per share attributable to common stockholders, basic	$ (1.54)	$ (3.37)
Net loss per share attributable to common stockholders, diluted	$ (1.54)	$ (3.37)
Common Stock [Member]
Earnings Per Share Basic [Line Items]
Weighted average shares of common stock outstanding, basic	19,567,635	7,507,155
Weighted average shares of common stock outstanding, diluted	19,567,635	7,507,155

- 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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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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Amount, after deduction of tax, noncontrolling interests, dividends on preferred stock and participating securities; of income (loss) available to common shareholders.

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+ Details

Net Loss per Share - Schedule of Antidilutive Securities Excluded from Calculation of Diluted Net Loss per Share Attributable to Common Stockholders (Detail) - shares	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net loss per share	2,955,080	1,946,525
Options to Purchase Shares of Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net loss per share	2,113,510	1,433,968
Unvested Restricted Stock Units [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Common stock equivalents excluded from calculation of diluted net loss per share	841,570	512,557

Restructuring - Addition Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Nov. 30, 2022	Apr. 30, 2022	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2022	Mar. 31, 2024
April 2022 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of headcount reduced, percentage		35.00%
Restructuring charges related to severance payment and other employee-related costs		$ 1,520
November 2022 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Number of headcount reduced, percentage	18.00%
Restructuring charges related to severance payment and other employee-related costs				$ 5,658
Restructuring charges were paid			$ 2,348		$ 1,737
November 2022 Plan [Member] \| Forcast [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring charges expected to be paid						$ 1,573

Restructuring - Schedule of Accrued Restructuring Charges (Detail) - One-Time Employee Termination Benefits [Member] - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022
April 2022 Corporate Strategy Change [Member]
Restructuring Cost and Reserve [Line Items]
Accrual recorded as a result of restructuring charges		$ 1,520
Amounts paid during the period		(1,520)
November 2022 Workforce Reduction plan [Member]
Restructuring Cost and Reserve [Line Items]
Accrued restructuring charges, beginning balance	$ 3,921
Accrual recorded as a result of restructuring charges		5,658
Amounts paid during the period	(2,348)	(1,737)
Accrued restructuring charges, ending balance	$ 1,573	$ 3,921