Generation Bio (GBIO) 10-Q 5 May 22 2022 Q1 Quarterly report Financial data

Cover Page

Cover Page - shares	3 Months Ended
	Mar. 31, 2022	Apr. 29, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2022
Document Transition Report	false
Entity File Number	001-39319
Entity Registrant Name	GENERATION BIO CO.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-4301284
Entity Address, Address Line One	301 Binney Street
Entity Address, City or Town	Cambridge
Entity Address, State or Province	MA
Entity Address, Postal Zip Code	02142
City Area Code	617
Local Phone Number	655-7500
Title of 12(b) Security	Common Stock, $0.0001 Par Value
Trading Symbol	GBIO
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		57,087,958
Entity Central Index Key	0001733294
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 336,978	$ 375,145
Prepaid expenses and other current assets	4,585	4,041
Total current assets	341,563	379,186
Property and equipment, net	27,846	25,886
Operating lease right-of-use assets	62,882	65,143
Restricted cash	5,692	5,692
Deferred offering costs	461	461
Other long-term assets	5,582	403
Total assets	444,026	476,771
Current liabilities:
Accounts payable	1,547	2,023
Accrued expenses and other current liabilities	8,927	12,177
Operating lease liability	4,780	4,608
Total current liabilities	15,254	18,808
Operating lease liability, net of current portion	75,857	76,217
Total liabilities	91,111	95,025
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.0001 par value; 5,000,000 shares authorized and no shares issued or outstanding at March 31, 2022 and December 31, 2021
Common stock, $0.0001 par value; 150,000,000 shares authorized at March 31, 2022 and December 31, 2021; 57,004,128 and 56,980,701 shares issued at March 31, 2022 and December 31, 2021, respectively; 57,004,128 and 56,969,618 shares outstanding at March 31, 2022 and December 31, 2021, respectively	6	6
Additional paid-in capital	696,034	689,866
Accumulated deficit	(343,125)	(308,126)
Total stockholders' equity	352,915	381,746
Total liabilities and stockholders' equity	$ 444,026	$ 476,771

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Preferred stock, par value per share	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 0.0001	$ 0.0001
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	57,004,128	56,980,701
Common stock, shares outstanding	57,004,128	56,969,618

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 25,554	$ 18,753
General and administrative	9,790	6,902
Total operating expenses	35,344	25,655
Loss from operations	(35,344)	(25,655)
Other income:
Other income and interest income	345	93
Net loss and net loss attributable to common stockholders	$ (34,999)	$ (25,562)
Net loss per share attributable to common stockholders, basic	$ (0.61)	$ (0.46)
Net loss per share attributable to common stockholders, diluted	$ (0.61)	$ (0.46)
Weighted average common shares outstanding, basic	56,996,495	55,366,238
Weighted average common shares outstanding, diluted	56,996,495	55,366,238
Comprehensive loss:
Net loss	$ (34,999)	$ (25,562)
Other comprehensive loss:
Unrealized gains on marketable securities		1
Comprehensive loss	$ (34,999)	$ (25,561)

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Total
Beginning balance at Dec. 31, 2020	$ 5	$ 456,974	$ 9	$ (188,975)	$ 268,013
Beginning balance, shares at Dec. 31, 2020	46,291,877
Issuance of common stock upon exercise of stock options		1,519			1,519
Issuance of common stock upon exercise of stock options, shares	387,578
Vesting of restricted common stock, shares	215,074
Issuance of common stock upon public offering, net of issuance costs of $590	$ 1	211,285			211,286
Issuance of common stock upon public offering, net of issuance costs of $590, shares	9,200,000
Stock-based compensation expense		3,479			3,479
Unrealized gains on marketable securities			1		1
Net loss				(25,562)	(25,562)
Ending balance at Mar. 31, 2021	$ 6	673,257	$ 10	(214,537)	458,736
Ending balance, shares at Mar. 31, 2021	56,094,529
Beginning balance at Dec. 31, 2021	$ 6	689,866		(308,126)	381,746
Beginning balance, shares at Dec. 31, 2021	56,969,618
Issuance of common stock upon exercise of stock options		102			102
Issuance of common stock upon exercise of stock options, shares	21,787
Vesting of restricted common stock, shares	12,723
Stock-based compensation expense		6,066			6,066
Net loss				(34,999)	(34,999)
Ending balance at Mar. 31, 2022	$ 6	$ 696,034		$ (343,125)	$ 352,915
Ending balance, shares at Mar. 31, 2022	57,004,128

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) $ in Thousands	3 Months Ended
	Mar. 31, 2021USD ($)
IPO [Member]
Stock issuance of costs	$ 590

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (34,999)	$ (25,562)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	6,066	3,479
Depreciation and amortization expense	1,197	1,064
Amortization (accretion) of premium (discount) on marketable securities, net		260
Loss on sale of property and equipment	28
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(531)	704
Other noncurrent assets	(3,105)	(334)
Accounts payable	(684)	(145)
Accrued expenses and other current liabilities	(3,407)	(2,493)
Net cash used in operating activities	(35,435)	(23,027)
Cash flows from investing activities:
Purchases of property and equipment	(2,784)	(915)
Maturities of marketable securities		114,400
Net cash (used in) provided by investing activities	(2,784)	113,485
Cash flows from financing activities:
Proceeds from public offering of common stock, net of underwriting discounts and commissions		211,876
Payment of offering costs	(50)	(438)
Proceeds from exercise of stock options and other types of equity, net	102	1,519
Net cash provided by financing activities	52	212,957
Net increase in cash, cash equivalents and restricted cash	(38,167)	303,415
Cash, cash equivalents and restricted cash at beginning of period	380,837	64,940
Cash, cash equivalents and restricted cash at end of period	342,670	368,355
Supplemental disclosure of noncash investing and financing information:
Purchases of property and equipment included in accounts payable and accrued expenses	$ 1,928	64
Offering costs included in accounts payable and accrued expenses		$ 111

Nature of the Business and Basi

Nature of the Business and Basis of Presentation	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Generation Bio Co., or Generation Bio, was incorporated on October 21, 2016 as Torus Therapeutics, Inc. and subsequently changed its name to Generation Bio Co. Generation Bio Co. and its consolidated subsidiary, or the company, we, our or us, are innovating genetic medicines to provide durable, redosable treatments for potentially hundreds of millions of patients living with rare and prevalent diseases. Our non-viral genetic medicines platform incorporates our high-capacity DNA construct called closed-ended DNA, or ceDNA; our cell-targeted lipid nanoparticle delivery system, or ctLNP; and our highly scalable capsid-free manufacturing process that uses our proprietary cell-free rapid enzymatic synthesis, or RES, to produce ceDNA. Using our approach, we are developing novel genetic medicines to provide targeted delivery of genetic payloads that include large and multiple genes to a range of cell types across a broad array of diseases. We are also engineering our genetic medicines to be redosable, which may enable individualized patient titration to reach the desired therapeutic expression and to maintain efficacy throughout a patient’s life. We are headquartered in Cambridge, Massachusetts. We are 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 key personnel, protection of proprietary technology, compliance with government regulations, uncertainties regarding the timing and ability to complete the build-out of our manufacturing facility, the ability to establish clinical- and commercial-scale manufacturing processes and the ability to secure additional capital to fund operations. Programs currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization of a product. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if our development efforts are successful, it is uncertain when, if ever, we will realize significant revenue from product sales. In June 2020, we completed our initial public offering, or IPO, pursuant to which we issued and sold 12,105,263 shares of our common stock, including 1,578,947 shares pursuant to the full exercise of the underwriters’ option to purchase additional shares resulting in net proceeds of $210.7 million, after deducting underwriting discounts and commissions and other offering expenses. Upon the closing of the IPO, all of our outstanding convertible preferred stock automatically converted into shares of common stock. In January 2021, we issued and sold 9,200,000 shares of our common stock, including 1,200,000 shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, in a follow-on public offering, resulting in net proceeds of $211.3 million after deducting underwriting discounts and commissions and other offering expenses. The accompanying condensed consolidated financial statements have been prepared on the basis of continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. Since inception, we have funded our operations with proceeds from the sale of instruments convertible into convertible preferred stock (which converted into convertible preferred stock in 2017), the sales of convertible preferred stock (which converted into common stock in 2020), and most recently, the sale of common stock in underwritten public offerings. We have incurred recurring losses, including net losses of $35.0 million for the three months ended March 31, 2022 and $25.6 million for the three months ended March 31, 2021. As of March 31, 2022, we had an accumulated deficit of $343.1 million. We expect to continue to generate operating losses in the foreseeable future. As of May 5, 2022, the issuance date of these condensed consolidated financial statements, we expect that our cash and cash equivalents will be sufficient to fund our operating expenses and capital expenditure requirements for at least 12 months. We will need to obtain additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and/or licensing arrangements. We may not be able to obtain financing on acceptable terms, or at all, and we may not be able to enter into collaborative or strategic alliances or licensing arrangements. The terms of any financing may adversely affect the holdings or the rights of our stockholders. Arrangements with collaborators or others may require us to relinquish rights to certain of our technologies or programs. If we are unable to obtain funding, we could be forced to delay, reduce or eliminate some or all of our research and development programs, pipeline expansion or commercialization efforts, which could adversely affect our business prospects. Although management will continue to pursue these plans, there is no assurance that we will be successful in obtaining sufficient funding on terms acceptable to us to fund continuing operations when needed or at all. The accompanying condensed consolidated financial statements reflect the operations of Generation Bio and our wholly owned subsidiary, Generation Bio Securities Corporation. Intercompany balances and transactions have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in conformity with generally accepted accounting principles in the United States of America, or GAAP. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification, or ASC, and Accounting Standards Update, or ASU, of the Financial Accounting Standards Board, or FASB.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and stock-based compensation expense. We base our estimates on historical experience, known trends and other market-specific or other relevant factors that we believe to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions. Unaudited interim financial information The condensed consolidated balance sheet as of December 31, 2021 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying unaudited financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021 have been prepared by us pursuant to the rules and regulations of the Securities and Exchange Commission, or SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These financial statements should be read in conjunction with our audited financial statements included in our Annual Report on Form 10-K that was most recently filed with the SEC. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair presentation of our financial position as of March 31, 2022, the results of operations for the three months ended March 31, 2022 and 2021, and cash flows for the three months ended March 31, 2022 and 2021 have been made. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2022 or any other period. Our significant accounting policies are described in Note 2 of the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2021. ​ ​ ​

Accrued Expenses

Accrued Expenses	3 Months Ended
	Mar. 31, 2022
Payables and Accruals [Abstract]
Accrued expenses	3. Accrued Expenses Accrued expenses and other current liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2022 ​ December 31, 2021 (in thousands) ​ ​ ​ ​ ​ Accrued employee compensation and benefits ​ $ 3,392 ​ $ 7,579 Accrued external research and development expenses ​ 1,969 ​ 2,091 Property and equipment ​ ​ 1,720 ​ ​ 869 Accrued professional fees ​ 930 ​ 962 Other ​ 916 ​ 676 Total ​ $ 8,927 ​ $ 12,177 ​

Equity

Equity	3 Months Ended
	Mar. 31, 2022
Equity [Abstract]
Equity	4. Equity As of March 31, 2022, our amended and restated certificate of incorporation authorizes us to issue 150,000,000 shares of common stock, par value $0.0001 per share, and 5,000,000 shares of preferred stock, par value $0.0001 per share, all of which preferred stock is undesignated. In January 2021, we issued and sold 9,200,000 shares of our common stock, including 1,200,000 shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, in a follow-on public offering, resulting in net proceeds of $211.3 million after deducting underwriting discounts and commissions and other offering expenses. Each share of common stock entitles the holder to one vote on all matters submitted to a vote of our stockholders. Holders of common stock are not entitled to receive dividends, unless declared by the board of directors.

Stock-Based Compensation

Stock-Based Compensation	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Stock-based compensation	5. Stock-Based Compensation Stock incentive plans Our 2017 Stock Incentive Plan, or the 2017 Plan, provided for us to grant incentive stock options or nonstatutory stock options, restricted stock, restricted stock units and other equity awards to employees, non-employees, and directors. In January 2020, the number of shares of common stock authorized for issuance under the 2017 Plan was increased from 8,407,405 shares to 10,275,717 shares. In May 2020, our board of directors adopted, and in June 2020, our stockholders approved, the 2020 Stock Incentive Plan, or the 2020 Plan, and, together with the 2017 Plan, the Plans, which became effective on June 11, 2020. The 2020 Plan provides for the grant of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, restricted stock units and other stock-based awards. The number of shares of common stock reserved for issuance under the 2020 Plan is the sum of (1) 2,547,698 shares; plus (2) the number of shares (up to a maximum of 7,173,014 shares) as was equal to the sum of (x) the number of shares of common stock reserved for issuance under the 2017 Plan that remained available for grant under the 2017 Plan on June 11, 2020 and (y) the number of shares of common stock subject to outstanding awards granted under the 2017 Plan that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by us at their original issuance price pursuant to a contractual repurchase right; plus (3) an annual increase, to be added on the first day of each fiscal year, beginning with the fiscal year ending December 31, 2021 and continuing until, and including, the fiscal year ending December 31, 2030, equal to the lesser of (i) 4% of the number of shares of common stock outstanding on such date, and (ii) an amount determined by the board of directors. In January 2021 and 2022, the number of shares of common stock authorized for issuance under the 2020 Plan was increased from 10,275,717 shares to 12,154,517 shares and from 12,154,517 shares to 14,433,745 shares, respectively. Upon the effectiveness of the 2020 Plan, we ceased granting additional awards under the 2017 Plan. The Plans are administered by the board of directors or, at the discretion of the board of directors, by a committee of the board of directors. The exercise prices, vesting and other restrictions on any award under the Plans are determined at the discretion of the board of directors, or its committee if so delegated. Stock options granted under the Plans with service-based vesting conditions generally vest over four years and expire after ten years. The exercise price for stock options granted is not less than the fair value of common stock as of the date of grant. Prior to our IPO, fair value of common stock was determined by the board of directors. Subsequent to our IPO, fair value of common stock is based on quoted market prices. As of March 31, 2022, 1,113,191 shares remained available for future issuance under the 2020 Plan. Shares subject to outstanding awards granted under the Plans that expire, terminate or are otherwise surrendered, cancelled, forfeited or repurchased by us at their original issuance price pursuant to a contractual repurchase right will be available for future awards under the 2020 Plan. Grant of stock options During the three months ended March 31, 2022, we granted service-based options to certain employees for the purchase of 2,537,390 shares of common stock with a weighted average grant date fair value of $4.77 per share that vest over a weighted average period of approximately four years. Restricted stock units During the three months ended March 31, 2022, we issued 1,604,809 restricted stock units with a fair value of $10.4 million that vest over a weighted average period of approximately 2.2 years. Employee stock purchase plan In May 2020, our board of directors adopted, and in June 2020, our stockholders approved, the 2020 Employee Stock Purchase Plan, or the 2020 ESPP, which became effective June 11, 2020. The 2020 ESPP is administered by our board of directors or by a committee appointed by the board of directors. The number of shares of common stock reserved for issuance under the 2020 ESPP automatically increases on the first day of each fiscal year, beginning with the fiscal year that commenced on January 1, 2021 and continuing for each fiscal year until, and including the fiscal year commencing on, January 1, 2030, in an amount equal to the lowest of (1) 1,302,157 shares of common stock, (2) 1% of the number of shares of common stock outstanding on such date, and (3) an amount determined by the board of directors. In January 2022, the number of shares of common stock authorized for issuance under the 2020 ESPP was increased from 950,931 shares to 1,520,738 shares. As of March 31, 2022, 1,482,231 shares remained available for issuance under the 2020 ESPP . Stock-based compensation Stock-based compensation expense was classified in the condensed consolidated statements of operations and comprehensive loss as follows: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ (in thousands) 2022 2021 ​ Research and development expenses ​ $ 3,151 ​ $ 1,898 ​ General and administrative expenses ​ 2,915 ​ 1,581 ​ Total ​ $ 6,066 ​ $ 3,479 ​ ​ As of March 31, 2022, total unrecognized compensation cost related to unvested stock options and restricted common stock was $61.2 million, with $52.0 million expected to be recognized over a weighted average period of 2.8 years and $9.2 million expected to be recognized over a weighted average period of 2.0 years, respectively. Additionally, as of March 31, 2022, we had unrecognized compensation cost related to unvested stock options with performance-based vesting conditions for which performance has not been deemed probable of $1.8 million.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	6. Commitments and Contingencies ​ ​ 401(k) Plan We have a defined-contribution plan under Section 401(k) of the Internal Revenue Code of 1986, as amended, or the 401(k) Plan. The 401(k) Plan covers all employees who meet defined minimum age and service requirements and allows participants to contribute a portion of their annual compensation on a pre-tax and/or after-tax basis. In September 2020, we adopted a match program, beginning on January 1, 2021, for employee contributions to the 401(k) Plan up to a maximum of four percent of the employee’s salary , subject to the maximums established under the Indemnification agreements In the ordinary course of business, we may provide indemnification of varying scope and terms to vendors, lessors, contract research organizations, 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, we have entered into indemnification agreements with members of our board of directors and our officers that will require us, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. The maximum potential amount of future payments we could be required to make under these indemnification agreements is, in many cases, unlimited. We have not incurred any material costs as a result of such indemnifications and are not currently aware of any indemnification claims. ​ Legal proceedings We, from time to time, may be party to litigation arising in the ordinary course of business. We were not subject to any material legal proceedings during the three months ended March 31, 2022. ​

Net Loss per Share

Net Loss per Share	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Net Loss per Share	7 ​ We have generated a net loss in all periods presented, therefore the basic and diluted net loss per share attributable to common stockholders are the same as the inclusion of the potentially dilutive securities would be anti-dilutive. We excluded the following potential common shares, presented based on amounts outstanding at each period end, from the computation of diluted net loss per share attributable to common stockholders for the periods indicated: ​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2022 2021 ​ Unvested restricted common stock — 482,728 ​ Unvested restricted common stock units ​ 1,537,744 ​ 18,040 ​ Stock options to purchase common stock 8,473,696 5,801,170 ​ Total 10,011,440 6,301,938 ​ ​ ​ ​

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2022
Accounting Policies [Abstract]
Use of estimates	Use of estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting periods. Significant estimates and assumptions reflected in these condensed consolidated financial statements include, but are not limited to, the accrual of research and development expenses and stock-based compensation expense. We base our estimates on historical experience, known trends and other market-specific or other relevant factors that we believe to be reasonable under the circumstances. On an ongoing basis, management evaluates its estimates, as there are changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results may differ from those estimates or assumptions.
Unaudited interim financial information	Unaudited interim financial information The condensed consolidated balance sheet as of December 31, 2021 was derived from audited financial statements but does not include all disclosures required by GAAP. The accompanying unaudited financial statements as of March 31, 2022 and for the three months ended March 31, 2022 and 2021 have been prepared by us pursuant to the rules and regulations of the Securities and Exchange Commission, or SEC, for interim financial statements. Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations. These financial statements should be read in conjunction with our audited financial statements included in our Annual Report on Form 10-K that was most recently filed with the SEC. In the opinion of management, all adjustments, consisting only of normal recurring adjustments necessary for a fair presentation of our financial position as of March 31, 2022, the results of operations for the three months ended March 31, 2022 and 2021, and cash flows for the three months ended March 31, 2022 and 2021 have been made. The results of operations for the three months ended March 31, 2022 are not necessarily indicative of the results of operations that may be expected for the year ending December 31, 2022 or any other period. Our significant accounting policies are described in Note 2 of the Notes to Consolidated Financial Statements included in our Annual Report on Form 10-K for the year ended December 31, 2021.

Accrued Expenses (Tables)

Accrued Expenses (Tables)	3 Months Ended
	Mar. 31, 2022
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	Accrued expenses and other current liabilities consisted of the following: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ March 31, 2022 ​ December 31, 2021 (in thousands) ​ ​ ​ ​ ​ Accrued employee compensation and benefits ​ $ 3,392 ​ $ 7,579 Accrued external research and development expenses ​ 1,969 ​ 2,091 Property and equipment ​ ​ 1,720 ​ ​ 869 Accrued professional fees ​ 930 ​ 962 Other ​ 916 ​ 676 Total ​ $ 8,927 ​ $ 12,177

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	3 Months Ended
	Mar. 31, 2022
Share-based Payment Arrangement [Abstract]
Summary of stock-based compensation expense was classified in the statements of operations and comprehensive loss	​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ Three Months Ended March 31, ​ (in thousands) 2022 2021 ​ Research and development expenses ​ $ 3,151 ​ $ 1,898 ​ General and administrative expenses ​ 2,915 ​ 1,581 ​ Total ​ $ 6,066 ​ $ 3,479 ​

Net Loss per Share (Tables)

Net Loss per Share (Tables)	3 Months Ended
	Mar. 31, 2022
Earnings Per Share [Abstract]
Summary of potential dilutive securities, presented based on amounts outstanding	​ ​ ​ ​ ​ ​ ​ ​ March 31, ​ ​ 2022 2021 ​ Unvested restricted common stock — 482,728 ​ Unvested restricted common stock units ​ 1,537,744 ​ 18,040 ​ Stock options to purchase common stock 8,473,696 5,801,170 ​ Total 10,011,440 6,301,938 ​ ​ ​

Nature of the Business and Ba_2

Nature of the Business and Basis of Presentation - Additional information (Detail) - USD ($) $ in Thousands	Jun. 16, 2020	Jan. 31, 2021	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Date of incorporation			Oct. 21, 2016
Net proceeds from shares issued		$ 211,300
Net loss			$ (34,999)	$ (25,562)
Accumulated deficit			$ (343,125)		$ (308,126)
Common Stock [Member]
Shares issued during the period		9,200,000		9,200,000
Common Stock [Member] | IPO [Member]
Shares issued during the period	12,105,263
Net proceeds from shares issued	$ 210,700
Common Stock [Member] | Over-Allotment Option [Member]
Shares issued during the period	1,578,947	1,200,000

Accrued Expenses - Summary of A

Accrued Expenses - Summary of Accrued expenses (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Payables and Accruals [Abstract]
Accrued employee compensation and benefits	$ 3,392	$ 7,579
Accrued external research and development expenses	1,969	2,091
Property and equipment	1,720	869
Accrued professional fees	930	962
Other	916	676
Total	$ 8,927	$ 12,177

Equity - Additional Information

Equity - Additional Information (Detail)	Jun. 16, 2020shares	Aug. 31, 2021USD ($)	Jan. 31, 2021USD ($)shares	Mar. 31, 2022USD ($)$ / sharesshares	Mar. 31, 2021shares	Dec. 31, 2021$ / sharesshares
Common stock, shares authorized				150,000,000		150,000,000
Common stock, par value per share | $ / shares				$ 0.0001		$ 0.0001
Preferred stock, shares authorized				5,000,000		5,000,000
Preferred stock, par value per share | $ / shares				$ 0.0001		$ 0.0001
Net proceeds from shares issued | $			$ 211,300,000
Number of vote per common share | $				1
Maximum
Aggregate gross offering price | $		$ 250,000,000
Common Stock [Member]
Shares issued during the period			9,200,000		9,200,000
Over-Allotment Option [Member] | Common Stock [Member]
Shares issued during the period	1,578,947		1,200,000

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	Jun. 11, 2020	Mar. 31, 2022	Jan. 31, 2022	Dec. 31, 2021	Jan. 31, 2021	Dec. 31, 2020	Jan. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock compensation on account of unvested options		$ 61.2
Unrecognized stock compensation on account of unvested options remaining period over which the compensation is to be recognized		2 years 9 months 18 days
Unvested Stock Awards for Which Performance is not Probable
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock compensation on account of unvested options		$ 1.8
Service Based Options [Member] | Certain Employees Directors And Consultants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement number of options granted		2,537,390
Share based compensation by share based fair value		$ 4.77
Share based compensation by share based payment weighted average period		4 years
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized stock compensation on account of unvested options remaining period over which the compensation is to be recognized		2 years
Unrecognized stock compensation on account of restricted common stock		$ 9.2
Shares issued		1,604,809
Fair value		$ 10.4
Weighted average period		2 years 2 months 12 days
2020 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for future issuance	2,547,698
Stock based compensation vesting period service based		4 years
Stock based compensation period of expiry		10 years
Common stock shares available for future issuance		1,113,191
Unrecognized stock compensation on account of unvested options		$ 52
2020 Stock Incentive Plan | Maximum | Additional From 2017 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for future issuance	7,173,014
2020 Stock Incentive Plan | Maximum | Annual Increase 2021 To 2030
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of common stock shares additionally reserved for issuance	4.00%
Employee Stock Purchase Plan 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock reserved for future issuance		1,520,738		950,931
Common stock shares available for future issuance		1,482,231
Employee Stock Purchase Plan 2020 | Maximum | Annual Increase 2021 To 2030
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of common stock shares additionally reserved for issuance	1.00%
Number of share instruments newly issued under a share-based compensation plan	1,302,157
Common Stock [Member] | 2017 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement number of shares authorized for issuance							10,275,717	8,407,405
Common Stock [Member] | 2020 Stock Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation by share based payment arrangement number of shares authorized for issuance			14,433,745	12,154,517	12,154,517	10,275,717

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Stock-Based Compensation Expense was Classified in the Statements of Operations and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 6,066	$ 3,479
Research and development expense [Member]
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	3,151	1,898
General and administrative expenses
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Stock-based compensation expense	$ 2,915	$ 1,581

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Mar. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Defined contribution plan, percentage	4.00%

Net Loss per Share - Summary of

Net Loss per Share - Summary of Potential Dilutive Securities, Presented Based on Amounts Outstanding (Detail) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive net loss per share	10,011,440	6,301,938
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive net loss per share		482,728
Unvested restricted common stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive net loss per share	1,537,744	18,040
Stock option to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive net loss per share	8,473,696	5,801,170