TScan Therapeutics (TCRX) 10-Q 19 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 16, 2021
Document Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2021
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q2
Trading Symbol	TCRX
Entity Registrant Name	TSCAN THERAPEUTICS, INC.
Entity Central Index Key	0001783328
Entity Current Reporting Status	No
Entity Interactive Data Current	Yes
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	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	001-40603
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	82-5282075
Entity Address, Address Line One	830 Winter Street
Entity Address, State or Province	MA
Entity Address, City or Town	Waltham
Entity Address, Postal Zip Code	02451
City Area Code	857
Local Phone Number	399-9500
Title of 12(b) Security	Voting Common Stock, $0.0001 par value per share
Security Exchange Name	NASDAQ
Voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		18,822,590
Non-voting Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		5,143,134

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 106,197,000	$ 34,791,000
Prepaid expenses and other current assets	3,873,000	1,654,000
Total current assets	110,070,000	36,445,000
Deferred offering costs	2,540,000
Property and equipment, net	10,451,000	5,659,000
Right-of-use assets	6,185,000	6,873,000
Restricted cash	595,000	595,000
Long-term deposit	166,000	166,000
Total assets	130,007,000	49,738,000
Current liabilities:
Accounts payable	3,547,000	2,910,000
Accrued expenses and other current liabilities	3,749,000	2,494,000
Operating lease liability, current portion	1,575,000	1,415,000
Deferred revenue, current portion	11,746,000	10,627,000
Total current liabilities	20,617,000	17,446,000
Deferred revenue, net of current portion	4,560,000	8,816,000
Operating lease liability, net of current portion	5,211,000	6,019,000
Other long term liabilities	238,000	238,000
Total liabilities	30,626,000	32,519,000
Commitments and contingencies (Note 8)
Convertible preferred stock (Note 5)	159,411,000	59,681,000
Stockholders' deficit:
Common stock, $0.0001 par value; 165,210,543 shares authorized; 1,682,805 and 1,574,138 shares issued; and 1,419,819 and 1,135,858 shares issued outstanding at June 30, 2021 and December 31, 2020, respectively	1,000	1,000
Additional paid-in capital	2,088,000	1,070,000
Accumulated deficit	(62,119,000)	(43,533,000)
Total stockholders' deficit	(60,030,000)	(42,462,000)
Total liabilities, convertible preferred stock and stockholders' deficit	$ 130,007,000	$ 49,738,000

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	165,210,543	165,210,543
Common stock, shares issued	1,682,805	1,574,138
Common stock, shares outstanding	1,419,819	1,135,858

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue
Collaboration and license revenue	$ 2,848		$ 4,875
Revenue from Contract with Customer, Products and Services [Extensible List]	http://www.tscan.com/#CollaborationAndLicenseRevenueMember	http://www.tscan.com/#CollaborationAndLicenseRevenueMember	http://www.tscan.com/#CollaborationAndLicenseRevenueMember	http://www.tscan.com/#CollaborationAndLicenseRevenueMember
Operating expenses:
Research and development	$ 10,801	$ 4,502	$ 18,140	$ 8,800
General and administrative	2,726	1,114	5,332	2,452
Total operating expenses	13,527	5,616	23,472	11,252
Loss from operations	(10,679)	(5,616)	(18,597)	(11,252)
Other income:
Interest income	5	3	11	102
Net loss	$ (10,674)	$ (5,613)	$ (18,586)	$ (11,150)
Net loss per share, basic and diluted	$ (7.69)	$ (6.18)	$ (14.25)	$ (13.23)
Weighted average common shares outstanding—basic and diluted	1,387,973	908,564	1,303,899	842,643

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Unaudited) - USD ($)	Total	Convertible Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Deficit
Balances at Dec. 31, 2019	$ (17,138,000)			$ 268,000	$ (17,406,000)
Balances, shares at Dec. 31, 2019		7,063,104
Balances at Dec. 31, 2019		$ 59,681,000
Balances, shares at Dec. 31, 2019			642,903
Exercise of stock options	247,000		$ 1,000	246,000
Exercise of stock options, shares			124,828
Vesting of restricted common stock, shares			176,574
Stock-based compensation expense	237,000			237,000
Net loss	(11,150,000)				(11,150,000)
Balances at Jun. 30, 2020	(27,804,000)		$ 1,000	751,000	(28,556,000)
Balances, shares at Jun. 30, 2020		7,063,104
Balances at Jun. 30, 2020		$ 59,681,000
Balances, shares at Jun. 30, 2020			944,305
Balances at Mar. 31, 2020	(22,343,000)		$ 1,000	599,000	(22,943,000)
Balances, shares at Mar. 31, 2020		7,063,104
Balances at Mar. 31, 2020		$ 59,681,000
Balances, shares at Mar. 31, 2020			843,589
Exercise of stock options	26,000			26,000
Exercise of stock options, shares			13,064
Vesting of restricted common stock, shares			87,652
Stock-based compensation expense	126,000			126,000
Net loss	(5,613,000)				(5,613,000)
Balances at Jun. 30, 2020	(27,804,000)		$ 1,000	751,000	(28,556,000)
Balances, shares at Jun. 30, 2020		7,063,104
Balances at Jun. 30, 2020		$ 59,681,000
Balances, shares at Jun. 30, 2020			944,305
Balances at Dec. 31, 2020	(42,462,000)		$ 1,000	1,070,000	(43,533,000)
Balances, shares at Dec. 31, 2020		7,063,104
Balances at Dec. 31, 2020	$ 59,681,000	$ 59,681,000
Balances, shares at Dec. 31, 2020	1,135,858		1,135,858
Issuance of Series C convertible preferred stock (net of issuance costs of $270)		$ 99,730,000
Issuance of Series C convertible preferred stock (net of issuance costs of $270), shares		8,553,168
Exercise of stock options	$ 170,000			170,000
Exercise of stock options, shares			108,656
Vesting of restricted common stock, shares			175,305
Stock-based compensation expense	847,000			847,000
Net loss	(18,586,000)				(18,586,000)
Balances at Jun. 30, 2021	(60,030,000)		$ 1,000	2,088,000	(62,119,000)
Balances, shares at Jun. 30, 2021		15,616,272
Balances at Jun. 30, 2021	$ 159,411,000	$ 159,411,000
Balances, shares at Jun. 30, 2021	1,419,819		1,419,819
Balances at Mar. 31, 2021	$ (49,922,000)		$ 1,000	1,522,000	(51,445,000)
Balances, shares at Mar. 31, 2021		15,616,272
Balances at Mar. 31, 2021		$ 159,411,000
Balances, shares at Mar. 31, 2021			1,304,789
Exercise of stock options	63,000			63,000
Exercise of stock options, shares			27,378
Vesting of restricted common stock, shares			87,652
Stock-based compensation expense	503,000			503,000
Net loss	(10,674,000)				(10,674,000)
Balances at Jun. 30, 2021	(60,030,000)		$ 1,000	$ 2,088,000	$ (62,119,000)
Balances, shares at Jun. 30, 2021		15,616,272
Balances at Jun. 30, 2021	$ 159,411,000	$ 159,411,000
Balances, shares at Jun. 30, 2021	1,419,819		1,419,819

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Deficit (Unaudited) (Parenthetical) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Convertible Preferred Stock
Net issuance costs	$ 270

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (18,586)	$ (11,150)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	1,130	488
Stock-based compensation	847	236
Changes in current assets and liabilities:
Prepaid expenses and other assets	(2,219)	(22)
Right-of-use assets and lease liabilities, net	40	258
Accounts payable	1,593	505
Accrued expense and other liabilities	(325)	(198)
Deferred revenue	(3,137)	19,999
Net cash used in operating activities	(20,657)	10,116
Cash flows from investing activities:
Purchases of property and equipment	(6,877)	(1,510)
Net cash used in investing activities	(6,877)	(1,510)
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs	99,730
Proceeds from exercise of stock options	170	247
Payment of deferred offering costs	(960)
Net cash provided by financing activities	98,940	247
Net increase (decrease) in cash, cash equivalents and restricted cash	71,406	8,853
Cash, cash equivalents, and restricted cash - beginning of period	35,386	42,359
Cash, cash equivalents, and restricted cash - end of period	106,792	51,212
Supplemental cash flow information:
Purchase of property and equipment in accounts payable and accrued liabilities	379	$ 228
Deferred offering costs included in accrued expenses	$ 1,580

Nature of Business and Basis of

Nature of Business and Basis of Presentation	6 Months Ended
	Jun. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Nature of Business and Basis of Presentation	1. Nature of Business and Basis of Presentation Nature of Business TScan Therapeutics, Inc. and its wholly owned subsidiary, TScan Securities Corporation, (the Company) is a biotechnology company that was incorporated in Delaware on April 17, 2018 and has a principal place of business in Waltham, Massachusetts. The Company is a biopharmaceutical company focused on developing a pipeline of T cell receptor-engineered T cell (TCR-T) therapies for the treatment of patients with cancer. Initial Public Offering As further discussed in Note 11, in July 2021, the Company completed an initial public offering (IPO) of its voting common stock. Risks, Uncertainties and Going Concern The Company is subject to risks common to companies in the biotechnology industry, including, but not limited to, successful development of technology, obtaining additional funding, protection of proprietary technology, compliance with government regulations, risks of failure of preclinical studies, clinical studies and clinical trials, the need to obtain marketing approval for its product candidates and the ability to successfully market its therapies any products that receive approval, fluctuations in operating results, economic pressure impacting therapeutic pricing, dependence on key personnel, risks associated with changes in technologies, development by competitors of technological innovations and the ability to scale manufacturing to large scale production. Product candidates currently under development will require significant additional research and development efforts, including preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities. Even if the Company’s development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from therapy sales. The accompanying unaudited 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. Reverse Stock Split The Company’s board of directors (the Board) and stockholders approved a 1-for-8.2 reverse stock split of the Company’s issued and outstanding common stock and outstanding shares of preferred stock, which became effective on May 13, 2021. Accordingly, all share and per share amounts for all periods presented in the accompanying financial statements and notes thereto have been retroactively adjusted to reflect the reverse stock split. Impact of COVID-19 In December 2019, a novel strain of coronavirus, which causes the disease known as COVID-19, was reported to have surfaced in Wuhan, China. Since then, COVID-19 coronavirus has spread globally. In March 2020, the World Health Organization declared the COVID-19 outbreak a pandemic. The ongoing COVID-19 global and national health emergency has caused significant disruption in the international and United States economies and financial markets. The spread of COVID-19 has caused illness, quarantines, cancellation of events and travel, business and school shutdowns, reduction in business activity and financial transactions, labor shortages, supply chain interruptions and overall economic and financial market instability and business disruptions for the Company and many of the Company’s vendors. In response to public health directives and orders and to help minimize the risk of the virus to employees, the Company has taken a series of actions aimed at safeguarding the Company’s employees and business associates, including implementing a flexible work-at-home policy. These disruptions could result in increased costs of execution of development plans or may negatively impact the quality, quantity, timing and regulatory usability of data that the Company would otherwise be able to collect. While these disruptions are currently expected to be temporary, there is considerable uncertainty around the duration of these disruptions. Therefore, the related financial impact and duration cannot be reasonably estimated at this time. To date, the Company has not experienced material business disruptions, including with its vendors, as a result of the COVID-19 pandemic. Emerging Growth Company Status The Company qualifies as “emerging growth company” as defined in the Jumpstart Our Business Startups Act of 2012 and has elected to “opt in” to the extended transition related to complying with new or revised accounting standards, which means that when a standard is issued or revised and it has different application dates for public and nonpublic companies, the Company will adopt the new or revised standard at the time nonpublic companies adopt the new or revised standard and will do so until such time that the Company either (i) irrevocably elects to “opt out” of such extended transition period or (ii) no longer qualifies as an emerging growth company. The Company may choose to early adopt any new or revised accounting standards whenever such early adoption is permitted for nonpublic companies.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (US GAAP) and applicable rules and regulations of the Securities and Exchange Commission (the SEC) regarding interim financial reporting, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. Management believes that the interim financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position, results of its operations and cash flows. The condensed consolidated financial statements include the accounts of TScan Therapeutics, Inc. and its subsidiary TScan Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation. The results for the three and six months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and unaudited condensed consolidated statements included in the Company’s final prospectus related to the Company’s IPO dated July 15, 2021 and filed with the Securities Exchange Commission on July 16, 2021, pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the Prospectus). Deferred offering costs The Company capitalizes certain legal, professional accounting and other third-party fees that are directly associated with the IPO as deferred offering costs. The deferred offering costs will be offset against the IPO proceeds during the quarter ending September 30, 2021 as a result of the consummation of the IPO. The Company had no deferred costs capitalized as of December 31, 2020 and $2.5 million of deferred offering costs as of June 30, 2021.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	3. Fair Value Measurements The following tables set forth by level, within the fair value hierarchy, the assets (liabilities) carried at fair value (in thousands): Fair value measurements at June 30, 2021 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 104,414 $ - $ - $ 104,414 Total financial assets $ 104,414 $ - $ - $ 104,414 Fair value measurements at December 31, 2020 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents—money market funds $ 33,748 $ - $ - $ 33,748 Total financial assets $ 33,748 $ - $ - $ 33,748 The cash equivalents are comprised of funds held in an exchange traded money market fund and the fair value of the cash equivalents is determined based upon quoted market price for that fund. There were no transfers among Level 1, Level 2, or Level 3 categories in the periods presented. The carrying value of accounts payable and accrued expenses that are reported on the condensed consolidated balance sheets approximate their fair value due to the short-term nature of these assets and liabilities.

Accrued Expenses and Other Curr

Accrued Expenses and Other Current Liabilities	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Accrued Expenses and Other Current Liabilities	4. Accrued Expenses and Other Current Liabilities Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2021 2020 Accrued employee compensation and benefits $ 1,107 $ 1,535 Accrued consulting and professional services $ 368 $ 189 Accrued legal services and license fee $ 1,511 $ 578 Other $ 763 $ 192 Total accrued expenses and other current liabilities $ 3,749 $ 2,494

Convertible Preferred Stock

Convertible Preferred Stock	6 Months Ended
	Jun. 30, 2021
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	5. Convertible Preferred Stock Series A Preferred Stock In 2018, the Company entered into the Series A Preferred Stock Purchase Agreement with its founding investors providing $25 million in Series A Preferred Stock equity financing and issued 3,209,240 shares of Series A Preferred Stock. Issuance costs associated with the transaction were $0.1 million. Series B Preferred Stock In 2019, the Company entered into the Series B Preferred Stock Purchase Agreements providing $35 million in Series B Preferred Stock equity financing and issued 3,853,864 shares of Series B Preferred Stock. Issuance costs associated with the transaction were $0.2 million. Series C Preferred Stock In 2021, the Company entered into the Series C Preferred Stock Purchase Agreements providing $100 million in Series C Preferred Stock equity financing and issued 8,553,168 shares of Series C Preferred Stock. Issuance costs associated with the transaction were $0.3 million. As of each balance sheet date, the preferred stock consisted of the following (in thousands, except for share data): June 30, 2021 Preferred Stock Authorized Preferred Stock Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issuable Upon Conversion Series A Preferred Stock 26,315,790 3,209,240 $ 24,874 $ 32,484 3,209,240 Series B Preferred Stock 31,601,732 3,853,864 34,807 44,053 3,853,864 Series C Preferred Stock 70,136,064 8,553,168 99,730 105,342 8,553,168 Total 128,053,586 15,616,272 $ 159,411 $ 181,879 15,616,272 December 31, 2020 Preferred Stock Authorized Preferred Stock Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issuable Upon Conversion Series A Preferred Stock 26,315,790 3,209,240 $ 24,874 $ 29,838 3,209,240 Series B Preferred Stock 31,601,732 3,853,864 34,807 39,037 3,853,864 Total 57,917,522 7,063,104 $ 59,681.00 $ 68,875 7,063,104 The terms and conditions of the Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock (collectively the Preferred Stock) as of June 30, 2021 were as follows: Dividends Dividends shall accrue at the rate of 8% compounded annually and are cumulative in nature (Accruing Dividends). Dividends are payable only when and if declared by the Company’s Board. The Company shall not declare, pay, or set aside any dividends on shares of any class of common stock, unless the holders of the Preferred Stock shall first receive dividends on each outstanding share of Preferred Stock in the amount of the accrued dividends unpaid as of such date. No dividends have been declared or paid as of December 31, 2020 and June 30, 2021. The cumulative dividends at June 30, 2021 totaled $21.9 million. Liquidation In the event of any liquidation, dissolution, or winding-up of the Company, which would include the sale of the Company, the holders of the Preferred Stock are entitled to a liquidation preference. The amount to be paid to the holders of Preferred Stock is an amount equal to the greater of (i) the original purchase price per share, plus all Accruing Dividends accrued but unpaid thereon applicable to the series of Preferred Stock (which Accruing Dividends shall be paid out in cash), whether or not declared, together with any other dividends declared but unpaid thereon or (ii) such amount per share as would have been payable had all shares of Preferred Stock been converted to common stock prior to such liquidation, dissolution, or winding up of the Company. The original issue purchase price per share of the Series A Preferred Stock was $7.79 per share, the original issue price of the Series B Preferred Stock was $9.02 per share, and the original issue price of the Series C Preferred Stock was $11.70 per share. The holder of the Series C Preferred Stock are entitled to receive their respective liquidation preference with respect to the Series C Preferred Stock in full before any liquidation preference is paid upon the shares of Series A and B Preferred Stock. Then the holders of the Series B Preferred Stock are entitled to receive their respective liquidation preference with respect to the Series B Preferred Stock in full before any liquidation preference is paid upon the shares of Series A Preferred Stock. Any assets remaining following the preferential distribution to the holders of Series A Preferred Stock, Series B Preferred Stock, Series C Preferred Stock would be available for distribution ratably among the holders of common stock. Voting The holders of the Preferred Stock are entitled to the number of votes equal to the number of shares of common stock into which the shares of the Preferred Stock held by each holder are then convertible. The holders of Preferred Stock are entitled to vote together with the holders of the Company’s common stock, as a single class, on all matters submitted to a vote of stockholders. In addition, the holders of Series A Preferred Stock are entitled to elect four (4) directors, holders of Series B Preferred Stock are entitled to elect two (2) directors and holders of Series C Preferred Stock are entitled to elect one (1) director. Conversion The holders of Preferred Stock shall have the right to convert, at the option of the holder, at any time, into shares of common stock by dividing the preferred stock original issuance price by the conversion price in effect at the time. The initial Series A Preferred Stock conversion price is $7.79 per share, the initial Series B Preferred Stock conversion price is $9.02 per share and the initial Series C Preferred Stock conversion price is $11.70 per share, subject in each case to certain adjustments to reflect the issuance of common stock, options, warrants, or other rights to subscribe for or to purchase shares of the Company’s common stock for a consideration per share less than the conversion price then in effect. In addition, each share of Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock will automatically convert into shares of common stock at the applicable conversion ratio in effect upon the earlier of (a) the closing of a Qualified IPO (as defined in the Company’s certificate of incorporation) or (b) the date and time, or the occurrence of an event, specified by vote or written consent of the holders of at least fifty-nine percent (59%) of the then outstanding shares of Preferred Stock (voting together as a single class, and not as separate series, and on an as converted to common stock basis). Redemption The Preferred Stock is not redeemable at the option of the holder. However, upon certain change in control events that are outside of the Company’s control, including liquidation, sale or transfer of control of the Company, holders of the Preferred Stock can cause redemption of the Preferred Stock. Shares of Preferred Stock must be redeemed by the Company in an amount equal to the liquidation preference for each series of Preferred Stock. The Company classifies its Preferred Stock outside of stockholders’ deficit as certain change in control events are outside the Company’s control. As there is no certain redemption date and the redemption feature can only be triggered in the event of a liquidation, sale, or transfer of control of the Company or similar event, the Company has concluded that it is not probable that the Preferred Stock will become redeemable and as such does not accrete the Preferred Stock to the redemption value.

Stock Based Compensation

Stock Based Compensation	6 Months Ended
	Jun. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Based Compensation	6. Stock Based Compensation 2018 Equity Incentive Plan On April 20, 2018, the Company adopted the 2018 Stock Plan (the 2018 Plan). The 2018 Plan, as amended, provides for the issuance of up to 2,902,738 shares of common stock to employees, officers, directors, consultants, and advisors in the form of nonqualified and incentive stock options, unvested stock awards, and other stock-based awards. As of June 30, 2021, there were 157,902 shares of common stock available for issuance under the 2018 Plan. 2021 Equity Incentive Plan The 2021 Equity Incentive Plan (the 2021 Plan) was approved by the Company’s Board on April 22, 2021 and became effective immediately, although no awards were permitted to be granted under the 2021 Plan until July 15, 2021. The 2021 Plan replaced the 2018 Plan. However, awards outstanding under the 2018 Plan will continue to be governed by their existing terms. There are 3,278,048 shares of common stock available for issuance under the 2021 Plan, plus up to 157,902 shares available for issuance under, or issued pursuant to or subject to awards granted under, the 2018 Plan. The number of shares reserved for issuance under the 2021 Plan will be increased automatically on the first business day of each fiscal year, commencing in 2021 and ending in 2031. The aggregate number of common shares that may be issued under the 2021 Plan shall automatically increase by a number equal to the lesser of (a) 4% of the total number of shares of common stock actually issued and outstanding on the last day of the preceding fiscal year or (b) a number of shares common stock determined by the Company’s Board. 2021 Employee Stock Purchase Plan The 2021 Employee Stock Purchase Plan (the “2021 ESPP”) was approved by the Company’s Board on April 22, 2021 and became effective immediately, although no awards were permitted to be granted under the 2021 Plan until July 15, 2021. A total of 254,390 shares of common stock are initially reserved for issuance under the 2021 ESPP. The number of shares reserved for issuance will automatically be increased on the first business day of each fiscal year, commencing on January 1, 2022 and ending on January 1, 2041. The aggregate number of shares of common stock that may be issued under the 2021 ESPP shall automatically increase by a number equal to the least of (i) one percent (1%) of the total number of shares of common stock actually issued and outstanding on the last day of the preceding fiscal year, or (ii) a number of shares of common stock determined by the Company’s Board. Shares issued under the 2021 ESPP will be compensatory. Stock Options In general, stock options typically vest over four years and have a maximum term of 10 years. Also, the Company typically grants stock options to employees and non-employees at exercise prices deemed by the Board to be equal to the fair value of the common stock at the time of grant. The fair value of the common stock has been determined by the Board at each measurement date based on a variety of different factors, including the results obtained from third party appraisals, the Company’s financial position and historical financial performance, the status of development of the Company’s services, the current climate in the marketplace, the illiquid nature of the common stock, the effect of the rights and preferences of the preferred stockholders, and the prospects of a liquidity event, among others. The Company utilized the Black-Scholes option-pricing model to estimate the fair value of stock options awarded to employees. The Black-Scholes option-pricing model requires several key assumptions. The key assumptions used to apply this pricing model during the six months ended June 3 0 , 202 1 and 202 0 , were as follows: Six Months Ended June 30, 2021 2020 Risk free interest rate 0.67 % 1.10 % Expected term (in years) 6.07 6.06 Expected dividend yield 0 % 0 % Expected volatility of underlying common stock 73 % 71 % The risk-free interest rate was based on rates associated with U.S. Treasury issues approximating the expected life of the stock options. The expected term of stock options granted to employees was determined using the simplified method, which represents the midpoint of the contractual term of the stock option and the weighted-average vesting period of the option. The Company uses the simplified method because it does not have sufficient historical stock option exercise data to provide a reasonable basis upon which to estimate the expected term. The expected dividend-yield assumption was based on the Company’s expectation of no future dividend payments. The expected volatility of the underlying stock was based on the average historical volatility of comparable publicly traded companies based on weekly price returns as reported by a pricing service, as the Company does not have a trading history for its common stock. The following table summarizes the stock option activity under the 2018 Plan: Stock Options Weighted Average Exercise Price Weighted Average Remaining Life (in Years) Intrinsic Value (in thousands) Outstanding January 1, 2021 1,445,427 $ 2.62 8.74 $ 3,799 Granted 1,272,770 7.25 Exercised (108,656 ) 2.18 Canceled (118,377 ) 2.45 Outstanding June 30, 2021 2,491,164 $ 5.01 8.94 $ 22,235 Options vested or expected to vest as of June 30, 2021 2,491,164 $ 5.01 8.94 $ 22,235 Stock options exercisable as of June 30, 2021 456,750 $ 2.30 8.02 $ 5,315 The weighted average grant date fair value of stock options granted for the six months ended June 30, 2021 was $4.64 per share. Restricted Common Stock The Company has granted restricted common stock with service based vesting conditions. Unvested shares of restricted common stock may not be sold or transferred by the holder, except for transfers for estate planning purposes in which the transferee agrees to remain bound by all restrictions set forth in the original common stock purchase agreement. They are legally issued and outstanding but only accounted for as outstanding when vested. These restrictions lapse over the four year vesting term of each award. The purchase price of each share of restricted common stock was $0.001 per share. A summary of the activity for the six months ended June 30, 2021 is as follows: Number of Shares Weighted Average Grant Date Fair Value Unvested restricted stock as of January 1, 2021 438,280 $ 0.00 Vested (175,305 ) $ 0.00 Unvested restricted stock as of June 30, 2021 262,975 $ 0.00 The aggregate fair value of restricted stock awards that vested during the six months ended June 30, 2021 was nominal. Stock-Based Compensation Expense Stock-based compensation expense was as follows (in thousands): Six Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Research and development $ 356 $ 111 $ 205 $ 62 General and administrative 491 125 $ 298 $ 64 $ 847 $ 237 $ 503 $ 126 As of June 30, 2021, there was $6.6 million of unrecognized stock-based compensation expense related to unvested stock options and restricted common stock, which is estimated to be recognized over a period of 3.11 years.

Collaboration and License Agree

Collaboration and License Agreements	6 Months Ended
	Jun. 30, 2021
Collaboration And License Agreements [Abstract]
Collaboration and License Agreements	7. Collaboration and License Agreements Novartis In March 2020 The Company concluded that Novartis meets the definition of a customer, as the Company is delivering research and development activities and know-how rights. The Company identified performance obligations for research and development activities, data reporting and participation in joint steering and research committees. The Company determined there is a single performance obligation due to the services being highly interrelated and are therefore not distinct in the context of the contract. The Company combined the pre-option research services and data reporting into a single performance obligation Novartis has an exclusive option to obtain a commercial license for up to three Targets (as defined in the Novartis Agreement) to pursue further development and commercialization of the respective Target. Pursuant to the Novartis Agreement, the option for Novartis to license, develop, and commercialize Targets is not a performance obligation at the outset of the Novartis Agreement as it is a customer option that does not represent a material right. The Company looked to the promises in the arrangement to determine the method of recognition that best coincides with the pattern of delivery. The Company concluded that the performance of the research services over the expected research term was the predominant promise within the performance obligation. The Company is recognizing the revenue associated with the performance obligation using the input method, according to the actual costs incurred as a percentage of total expected costs to complete the research services. As costs are incurred, the Company will recognize revenue over time. Any change in the estimated percentage complete due to a revised cost forecast will be adjusted in the period in which the change in estimate occurs and the revenue recognition will be updated accordingly. The Company expects the research term to last approximately three years, which is inclusive of the option to extend the arrangement. The Company determined that the $20.0 million upfront payment, together with the $10.0 million of estimated research costs to be reimbursed by Novartis to be the entirety of the consideration to be included in the transaction price as of the outset of the arrangement. The potential milestone payments that the Company is eligible to receive were excluded from the transaction price, as all milestone amounts were fully constrained based on the assessed probability of achievement. The Company will re-evaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, and, if necessary, adjust the estimate of the transaction price. During the six months ended June 30, 2021, the Company recognized $4.7 million of revenue associated with the Novartis Agreement based on performance completed during that period. Additionally, during the six months ended June 30, 2021, the Company incurred $0.7 million of costs associated with the Novartis Agreement that were recorded within research and development expenses in the statements of operations. Additionally, as of June 30, 2021, the Company had current and long-term deferred revenue of $11.7 million and $4.6 million, respectively due to Novartis Agreement.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. Commitments and Contingencies Brigham and Women’s License Agreement The Company obtained the worldwide exclusive license to its foundational technology from The Brigham and Women’s Hospital, Inc. (or BWH). The license, as amended, grants worldwide exclusive use to the patent underlying the TargetScan technology in exchange for fees including development milestones and various royalties on product sales should they occur in the future. Royalty Agreement In June 2018, the Company amended and restated an existing royalty agreement with one of its founders. Under the amended and restated royalty agreement, the Company agreed to pay the founder an aggregate royalty of 1% of net sales of any product sold by the Company or by any of its direct or indirect licensees for use in the treatment of any disease or disorder covered by a pending patent application or issued patent held or controlled by the Company as of the last date that the founder was providing services to the Company as a director or consultant under a written agreement in perpetuity. Royalties are payable with respect to each applicable product for a defined period of time set forth in the royalty agreement. The founder assigned his rights and obligations under the royalty agreement to one of his affiliated entities in January 2021.

Net Loss Per Share

Net Loss Per Share	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share	9. Net Loss Per Share Net Loss Per Share Basic and diluted net loss per share was calculated as follows (in thousands, except share and per share data): Six Months Ended Three Months Ended June 30, June 30, 2021 2020 2021 2020 Numerator: Net loss $ (18,586 ) $ (11,150 ) $ (10,674 ) $ (5,613 ) Denominator: Weighted-average common shares outstanding, basic and diluted 1,303,899 842,643 1,387,973 908,564 Net loss per share, basic and diluted $ (14.25 ) $ (13.23 ) $ (7.69 ) $ (6.18 ) The Company excluded the following potential common shares from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Six Months Ended June 30, 2021 2020 Series A Preferred Stock (as converted to common stock) 3,209,240 3,209,240 Series B Preferred Stock (as converted to common stock) 3,853,864 3,853,864 Series C Preferred Stock (as converted to common stock) 8,553,168 - Unvested restricted common stock 262,975 646,605 Options to purchase common stock 2,491,164 1,383,150 Total 18,370,411 9,092,859

Related-Party Transactions

Related-Party Transactions	6 Months Ended
	Jun. 30, 2021
Related Party Transactions [Abstract]
Related-Party Transactions	10. Related-Party Transactions Novartis and its affiliates held shares of the Preferred Stock, including shares of Series C and Series B Preferred Stock, and is the customer in the Novartis Agreement discussed in Note 7.

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	11. Subsequent Events Initial Public Offering In July 2021, the Company completed the IPO in which the Company issued and sold 6,666,667 shares of its voting common stock at a public offering price of $15.00 per share, for aggregate gross proceeds of $100 million and its shares started trading on the Nasdaq Global Market under the ticker symbol “TCRX.” The Company received $90.5 million in net proceeds after deducting $7.0 million in underwriting discounts and commissions, and $2.5 million in offering costs borne by us. Upon closing of the IPO, all of the Company's outstanding shares of convertible preferred stock automatically converted into 15,616,272 shares of common stock (of which 5,143,134 shares are non-voting common stock). In connection with the closing of IPO, the Company amended and restated its in its entirety certificate of incorporation to, among other things: (i) authorize 300,000,000 shares of voting common stock; (ii) authorize 10,000,000 shares of non-voting common stock; (iii) eliminate all references to the previously existing series of preferred stock; and (iv) authorize 10,000,000 shares of preferred stock that may be issued from time to time by the Board in one or more series

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (US GAAP) and applicable rules and regulations of the Securities and Exchange Commission (the SEC) regarding interim financial reporting, and the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by US GAAP for complete financial statements. Management believes that the interim financial statements reflect all adjustments, which include only normal recurring adjustments necessary for the fair statement of the Company’s financial position, results of its operations and cash flows. The condensed consolidated financial statements include the accounts of TScan Therapeutics, Inc. and its subsidiary TScan Securities Corporation. All intercompany balances and transactions have been eliminated in consolidation. The results for the three and six months ended June 30, 2021 are not necessarily indicative of results to be expected for the year ending December 31, 2021, any other interim periods, or any future year or period. The accompanying condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and unaudited condensed consolidated statements included in the Company’s final prospectus related to the Company’s IPO dated July 15, 2021 and filed with the Securities Exchange Commission on July 16, 2021, pursuant to Rule 424(b) under the Securities Act of 1933, as amended (the Prospectus).
Deferred offering costs	Deferred offering costs

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Schedule of Assets and Liabilities Carried at Fair Value on a Heirarchy Basis	The following tables set forth by level, within the fair value hierarchy, the assets (liabilities) carried at fair value (in thousands): Fair value measurements at June 30, 2021 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents – money market funds $ 104,414 $ - $ - $ 104,414 Total financial assets $ 104,414 $ - $ - $ 104,414 Fair value measurements at December 31, 2020 using: Level 1 Level 2 Level 3 Total Assets Cash equivalents—money market funds $ 33,748 $ - $ - $ 33,748 Total financial assets $ 33,748 $ - $ - $ 33,748

Accrued Expenses and Other Cu_2

Accrued Expenses and Other Current Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Payables And Accruals [Abstract]
Schedule of Accrued Expenses and Other Current Liabilities	Accrued expenses and other current liabilities consisted of the following (in thousands): June 30, December 31, 2021 2020 Accrued employee compensation and benefits $ 1,107 $ 1,535 Accrued consulting and professional services $ 368 $ 189 Accrued legal services and license fee $ 1,511 $ 578 Other $ 763 $ 192 Total accrued expenses and other current liabilities $ 3,749 $ 2,494

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	6 Months Ended
	Jun. 30, 2021
Temporary Equity Disclosure [Abstract]
Schedule of Preferred Stock	As of each balance sheet date, the preferred stock consisted of the following (in thousands, except for share data): June 30, 2021 Preferred Stock Authorized Preferred Stock Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issuable Upon Conversion Series A Preferred Stock 26,315,790 3,209,240 $ 24,874 $ 32,484 3,209,240 Series B Preferred Stock 31,601,732 3,853,864 34,807 44,053 3,853,864 Series C Preferred Stock 70,136,064 8,553,168 99,730 105,342 8,553,168 Total 128,053,586 15,616,272 $ 159,411 $ 181,879 15,616,272 December 31, 2020 Preferred Stock Authorized Preferred Stock Issued and Outstanding Carrying Value Liquidation Preference Common Stock Issuable Upon Conversion Series A Preferred Stock 26,315,790 3,209,240 $ 24,874 $ 29,838 3,209,240 Series B Preferred Stock 31,601,732 3,853,864 34,807 39,037 3,853,864 Total 57,917,522 7,063,104 $ 59,681.00 $ 68,875 7,063,104

Stock Based Compensation (Table

Stock Based Compensation (Tables)	6 Months Ended
	Jun. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Key Assumptions Used for Black-Scholes Option-pricing Model to Estimate the Fair Value of Stock Options	The key assumptions used to apply this pricing model during the six months ended June 3 0 , 202 1 and 202 0 , were as follows: Six Months Ended June 30, 2021 2020 Risk free interest rate 0.67 % 1.10 % Expected term (in years) 6.07 6.06 Expected dividend yield 0 % 0 % Expected volatility of underlying common stock 73 % 71 %
Summary of Stock Option Activity	The following table summarizes the stock option activity under the 2018 Plan: Stock Options Weighted Average Exercise Price Weighted Average Remaining Life (in Years) Intrinsic Value (in thousands) Outstanding January 1, 2021 1,445,427 $ 2.62 8.74 $ 3,799 Granted 1,272,770 7.25 Exercised (108,656 ) 2.18 Canceled (118,377 ) 2.45 Outstanding June 30, 2021 2,491,164 $ 5.01 8.94 $ 22,235 Options vested or expected to vest as of June 30, 2021 2,491,164 $ 5.01 8.94 $ 22,235 Stock options exercisable as of June 30, 2021 456,750 $ 2.30 8.02 $ 5,315
Summary of Restricted Common Stock Activity	A summary of the activity for the six months ended June 30, 2021 is as follows: Number of Shares Weighted Average Grant Date Fair Value Unvested restricted stock as of January 1, 2021 438,280 $ 0.00 Vested (175,305 ) $ 0.00 Unvested restricted stock as of June 30, 2021 262,975 $ 0.00
Summary of Stock-based Compensation Expense	Stock-based compensation expense was as follows (in thousands): Six Months Ended June 30, Three Months Ended June 30, 2021 2020 2021 2020 Research and development $ 356 $ 111 $ 205 $ 62 General and administrative 491 125 $ 298 $ 64 $ 847 $ 237 $ 503 $ 126

Net Loss Per Share (Tables)

Net Loss Per Share (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Summary of Basic and Diluted Net Loss Per Share	Basic and diluted net loss per share was calculated as follows (in thousands, except share and per share data): Six Months Ended Three Months Ended June 30, June 30, 2021 2020 2021 2020 Numerator: Net loss $ (18,586 ) $ (11,150 ) $ (10,674 ) $ (5,613 ) Denominator: Weighted-average common shares outstanding, basic and diluted 1,303,899 842,643 1,387,973 908,564 Net loss per share, basic and diluted $ (14.25 ) $ (13.23 ) $ (7.69 ) $ (6.18 )
Summary of Potential Common Shares Excluded from Computation of Diluted Net Loss per Share	The Company excluded the following potential common shares from the computation of diluted net loss per share for the periods indicated because including them would have had an anti-dilutive effect: Six Months Ended June 30, 2021 2020 Series A Preferred Stock (as converted to common stock) 3,209,240 3,209,240 Series B Preferred Stock (as converted to common stock) 3,853,864 3,853,864 Series C Preferred Stock (as converted to common stock) 8,553,168 - Unvested restricted common stock 262,975 646,605 Options to purchase common stock 2,491,164 1,383,150 Total 18,370,411 9,092,859

Nature of Business and Basis _2

Nature of Business and Basis of Presentation - Additional Information (Details) $ in Thousands	May 13, 2021	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Date of incorporation				Apr. 17, 2018
Net losses		$ 10,674	$ 5,613	$ 18,586	$ 11,150
Accumulated deficit		$ 62,119		$ 62,119		$ 43,533
Reverse stock split				1-for-8.2
Reverse stock split conversion ratio	8.2

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Accounting Policies [Abstract]
Deferred offering cost	$ 2,500,000	$ 0

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Assets and Liabilities Carried at Fair Value on a Hierarchy Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Assets, Fair Value Disclosure [Abstract]
Total financial assets	$ 104,414	$ 33,748
Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	104,414	33,748
Level 1
Assets, Fair Value Disclosure [Abstract]
Total financial assets	104,414	33,748
Level 1 | Cash Equivalents - Money Market Funds
Assets, Fair Value Disclosure [Abstract]
Cash and cash equivalents fair value disclosure	$ 104,414	$ 33,748

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Fair Value Disclosures [Abstract]
Fair value, assets, level 1 to level 2 transfers	$ 0	$ 0
Fair value, assets, level 2 to level 1 transfers	0	0
Fair value, assets, transfers into level 3	0	0
Fair value, assets, transfers out of level 3	$ 0	$ 0

Accrued Expenses and Other Cu_3

Accrued Expenses and Other Current Liabilities - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Payables And Accruals [Abstract]
Accrued employee compensation and benefits	$ 1,107	$ 1,535
Accrued consulting and professional services	368	189
Accrued legal services and license fee	1,511	578
Other	763	192
Total accrued expenses and other current liabilities	$ 3,749	$ 2,494

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information (Details)	6 Months Ended	12 Months Ended
	Jun. 30, 2021USD ($)Director$ / sharesshares	Dec. 31, 2020USD ($)	Dec. 31, 2019USD ($)shares	Dec. 31, 2018USD ($)shares
Temporary Equity [Line Items]
Description of conversion terms for preferred stock	In addition, each share of Series A Preferred Stock, Series B Preferred Stock and Series C Preferred Stock will automatically convert into shares of common stock at the applicable conversion ratio in effect upon the earlier of (a) the closing of a Qualified IPO (as defined in the Company’s certificate of incorporation) or (b) the date and time, or the occurrence of an event, specified by vote or written consent of the holders of at least fifty-nine percent (59%) of the then outstanding shares of Preferred Stock (voting together as a single class, and not as separate series, and on an as converted to common stock basis).
Series A Preferred Stock
Temporary Equity [Line Items]
Preferred stock, value				$ 25,000,000
Preferred stock issued, shares | shares				3,209,240
Stock issuance costs				$ 100,000
Preferred stock, original issue purchase price per share | $ / shares	$ 7.79
Number of directors entitled to elect | Director	4
Preferred stock, conversion price | $ / shares	$ 7.79
Series B Preferred Stock
Temporary Equity [Line Items]
Preferred stock, value			$ 35,000,000
Preferred stock issued, shares | shares			3,853,864
Stock issuance costs			$ 200,000
Preferred stock, original issue purchase price per share | $ / shares	$ 9.02
Number of directors entitled to elect | Director	2
Preferred stock, conversion price | $ / shares	$ 9.02
Series C Preferred Stock
Temporary Equity [Line Items]
Preferred stock, value	$ 100,000,000
Preferred stock issued, shares | shares	8,553,168
Stock issuance costs	$ 300,000
Preferred stock, original issue purchase price per share | $ / shares	$ 11.70
Number of directors entitled to elect | Director	1
Preferred stock, conversion price | $ / shares	$ 11.70
Convertible Preferred Stock
Temporary Equity [Line Items]
Preferred stock, value	$ 99,730,000
Stock issuance costs	$ 270,000
Dividends accrual rate	8.00%
Dividends declared or paid	$ 0	$ 0
Cumulative dividends	$ 21,900,000

Convertible Preferred Stock - S

Convertible Preferred Stock - Schedule of Preferred Stock (Details) - USD ($)	Jun. 30, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Preferred Stock Authorized	128,053,586	57,917,522
Preferred Stock Issued and Outstanding	15,616,272	7,063,104
Carrying Value	$ 159,411,000	$ 59,681,000
Liquidation Preference	$ 181,879,000	$ 68,875,000
Common Stock Issuable Upon Conversion	15,616,272	7,063,104
Series A Preferred Stock
Temporary Equity [Line Items]
Preferred Stock Authorized	26,315,790	26,315,790
Preferred Stock Issued and Outstanding	3,209,240	3,209,240
Carrying Value	$ 24,874,000	$ 24,874,000
Liquidation Preference	$ 32,484,000	$ 29,838,000
Common Stock Issuable Upon Conversion	3,209,240	3,209,240
Series B Preferred Stock
Temporary Equity [Line Items]
Preferred Stock Authorized	31,601,732	31,601,732
Preferred Stock Issued and Outstanding	3,853,864	3,853,864
Carrying Value	$ 34,807,000	$ 34,807,000
Liquidation Preference	$ 44,053,000	$ 39,037,000
Common Stock Issuable Upon Conversion	3,853,864	3,853,864
Series C Preferred Stock
Temporary Equity [Line Items]
Preferred Stock Authorized	70,136,064
Preferred Stock Issued and Outstanding	8,553,168
Carrying Value	$ 99,730,000
Liquidation Preference	$ 105,342,000
Common Stock Issuable Upon Conversion	8,553,168

Stock Based Compensation - Addi

Stock Based Compensation - Additional Information (Details) - USD ($)	Jul. 15, 2021	Jun. 30, 2021	Jul. 14, 2021	Apr. 20, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation expense		$ 6,600,000
Weighted average period remaining (in years)		3 years 1 month 9 days
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options		4 years
Expected dividend-yield assumption		$ 0
Weighted average value of stock options, granted		$ 4.64
Restricted Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock, vesting term		4 years
Purchase price of restricted common stock		$ 0.001
Maximum | Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period of stock options		10 years
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan		157,902		2,902,738
2021 Equity Incentive Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan	3,278,048
Number of awards permitted to grant			0
Percentage of number of common stock issued and outstanding	4.00%
2021 Equity Incentive Plan | Maximum | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock shares under the plan	157,902
2021 Employee Stock Purchase Plan | Subsequent Event
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of awards permitted to grant			0
Percentage of number of common stock issued and outstanding	1.00%
Common stock, Reserved for future issuance	254,390

Stock Based Compensation - Key

Stock Based Compensation - Key Assumptions Used for Black-Scholes Option-pricing Model to Estimate the Fair Value of Stock Options (Details)	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Risk free interest rate	0.67%	1.10%
Expected term (in years)	6 years 25 days	6 years 21 days
Expected dividend yield	0.00%	0.00%
Expected volatility of underlying common stock	73.00%	71.00%

Stock Based Compensation - Summ

Stock Based Compensation - Summary of Stock Option Activity (Details) - Stock Options - 2018 Equity Incentive Plan $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021USD ($)$ / sharesshares	Dec. 31, 2020USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock Options Outstanding, Beginning balance | shares	1,445,427
Stock Options Outstanding, Granted | shares	1,272,770
Stock Options Outstanding, Exercised | shares	(108,656)
Stock Options Outstanding, Cancelled | shares	(118,377)
Stock Options Outstanding, Ending balance | shares	2,491,164	1,445,427
Stock Options vested or expected to vest | shares	2,491,164
Stock options exercisable | shares	456,750
Stock Options Outstanding, Weighted Average Exercise Price, Beginning Balance | $ / shares	$ 2.62
Stock Options Granted, Weighted Average Exercise Price | $ / shares	7.25
Stock Options Exercised, Weighted Average Exercise Price | $ / shares	2.18
Stock Options Cancelled, Weighted Average Exercise Price | $ / shares	2.45
Stock Options Outstanding, Weighted Average Exercise Price, Ending balance | $ / shares	5.01	$ 2.62
Stock Options vested or expected to vest, Weighted Average Exercise Price | $ / shares	5.01
Stock options exercisable, Weighted Average Exercise Price | $ / shares	$ 2.30
Stock Options Outstanding, Weighted Average Remaining Contractual Life	8 years 11 months 8 days	8 years 8 months 26 days
Stock Options vested or expected to vest, Weighted Average Remaining Contractual Life	8 years 11 months 8 days
Stock options exercisable, Weighted Average Remaining Contractual Life	8 years 7 days
Stock Options Outstanding, Intrinsic Value, Beginning | $	$ 3,799
Stock Options Outstanding, Intrinsic Value, Ending | $	22,235	$ 3,799
Stock Options vested or expected to vest, Intrinsic Value | $	22,235
Stock options exercisable, Intrinsic Value | $	$ 5,315

Stock Based Compensation - Su_2

Stock Based Compensation - Summary of Restricted Common Stock Activity (Details) - Restricted Common Stock	6 Months Ended
	Jun. 30, 2021$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested restricted stock, Beginning balance | shares	438,280
Unvested restricted stock, Vested | shares	(175,305)
Unvested restricted stock, Ending balance | shares	262,975
Unvested restricted stock, Weighted Average Grant Date Fair Value, Beginning balance | $ / shares	$ 0
Weighted Average Grant Date Fair Value, Vested | $ / shares	0
Unvested restricted stock, Weighted Average Grant Date Fair Value, Ending balance | $ / shares	$ 0

Stock Based Compensation - Su_3

Stock Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 503	$ 126	$ 847	$ 237
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	205	62	356	111
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 298	$ 64	$ 491	$ 125

Collaboration and License Agr_2

Collaboration and License Agreements - Additional Information (Details) $ in Thousands	Mar. 31, 2020USD ($)Target	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Dec. 31, 2020USD ($)
Collaboration And License Agreements [Line Items]
Collaboration and license revenue		$ 2,848		$ 4,875
Incurred costs		13,527	$ 5,616	23,472	$ 11,252
Deferred revenue, current portion		11,746		$ 11,746		$ 10,627
Novartis
Collaboration And License Agreements [Line Items]
License agreement date	Mar. 31, 2020
Upfront payment received	$ 20,000
Collaborations and license agreements, expected milestone receivable	$ 10,000
Collaboration period				180 days
Negotiation period				180-day
Expects research term	3 years
Revenue recognition milestone method milestone payables	$ 20,000
Estimated research costs transaction price	$ 10,000
Collaboration and license revenue				$ 4,700
Incurred costs				700
Deferred revenue, current portion		11,700		11,700
Long-term deferred revenue		$ 4,600		$ 4,600
Novartis | Maximum
Collaboration And License Agreements [Line Items]
Number of targets identified | Target	3

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Details)	Jun. 30, 2018
Royalty Agreement
Commitments And Contingencies Disclosure [Line Items]
Percentage of aggregate royalty of net sales of any product sold	1.00%

Net Loss Per Share - Summary of

Net Loss Per Share - Summary of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Earnings Per Share [Abstract]
Net loss	$ (10,674)	$ (5,613)	$ (18,586)	$ (11,150)
Weighted-average common shares outstanding, basic and diluted	1,387,973	908,564	1,303,899	842,643
Net loss per share, basic and diluted	$ (7.69)	$ (6.18)	$ (14.25)	$ (13.23)

Net Loss Per Share - Summary _2

Net Loss Per Share - Summary of Potential Common Shares Excluded from Computation of Diluted Net Loss per Share (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	18,370,411	9,092,859
Series A Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	3,209,240	3,209,240
Series B Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	3,853,864	3,853,864
Series C Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	8,553,168
Unvested Restricted Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	262,975	646,605
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Total	2,491,164	1,383,150

Subsequent Events - Additional

Subsequent Events - Additional Information (Details) - USD ($)	1 Months Ended
	Jul. 31, 2021	Jun. 30, 2021	Dec. 31, 2020
Subsequent Event [Line Items]
Deferred offering cost		$ 2,500,000	$ 0
Common stock issuable upon conversion		15,616,272	7,063,104
Common stock, shares authorized		165,210,543	165,210,543
Subsequent Event | Initial Public Offering | Common Stock
Subsequent Event [Line Items]
Common stock issuable upon conversion	15,616,272
Subsequent Event | Initial Public Offering | Preferred Stock
Subsequent Event [Line Items]
Preferred stock, shares authorized	10,000,000
Subsequent Event | Initial Public Offering | Voting Common Stock
Subsequent Event [Line Items]
Number of shares issued and sold	6,666,667
Sale of stock price per share	$ 15
Gross proceeds from issuance initial public offering	$ 100,000,000
Net proceeds from issuance of shares	90,500,000
Deferred offering cost	2,500,000
Underwriting discounts and commissions	$ 7,000,000
Common stock, shares authorized	300,000,000
Subsequent Event | Initial Public Offering | Non-voting Common Stock
Subsequent Event [Line Items]
Common stock issuable upon conversion	5,143,134
Common stock, shares authorized	10,000,000