Impel Pharmaceuticals (IMPL) 10-Q 16 Aug 21 2021 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2021	Aug. 11, 2021
Cover [Abstract]
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	IMPL
Entity Registrant Name	IMPEL NEUROPHARMA, INC.
Entity Central Index Key	0001445499
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Current Reporting Status	No
Entity Shell Company	false
Entity File Number	001-40353
Entity Tax Identification Number	26-3058238
Entity Address, Address Line One	201 Elliott Avenue West
Entity Address, Address Line Two	Suite 260
Entity Address, City or Town	Seattle
Entity Address, State or Province	WA
Entity Address, Postal Zip Code	98119
City Area Code	206
Local Phone Number	568-1466
Entity Common Stock, Shares Outstanding		19,509,619
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001 per share
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE
Document Quarterly Report	true
Document Transition Report	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheet (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 60,948	$ 7,095
Prepaid expenses and other current assets	4,619	1,077
Total current assets	65,567	8,172
Property and equipment, net	3,408	3,700
Other assets	187	187
Total assets	69,162	12,059
Current liabilities:
Accounts payable	5,461	4,314
Accrued liabilities	3,546	3,173
Current portion of term debt	0	417
Redeemable convertible preferred stock warrant liabilities	0	2,622
Total current liabilities	9,007	10,526
Convertible notes at fair value	0	0
Long-term debt	8,857	7,994
Total liabilities	17,864	18,520
Commitments and contingencies (Note 5)
Redeemable convertible preferred stock, $0.001 par value; 204,198,489 shares authorized at March 31, 2021 and December 31, 2020; [ ] and 202,009,981 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively; aggregate liquidation preference of $[ ] and $128,922 at March 3, 2021 and December 31, 2020, respectively	0	127,039
Stockholders' equity (deficit):
Preferred stock, $0.001 par value; 10,000,000 and - shares authorized at June 30, 2021 and December 31, 2020, respectively
Common stock, $0.001 par value; [ ] and 266,833,885 shares authorized at March 31, 2021 and December 31, 2020, respectively; [ ] and 755,478 shares issued and outstanding at March 31, 2021 and December 31, 2020, respectively	19	0
Additional paid-in capital	216,314	4,762
Accumulated deficit	(165,035)	(138,262)
Total stockholders' equity (deficit)	51,298	(133,500)
Total liabilities, redeemable convertible preferred stock and stockholders’ deficit	$ 69,162	$ 12,059

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheet (Parenthetical) (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Redeemable convertible preferred stock, par value	$ 0.001	$ 0.001
Redeemable convertible preferred stock, shares authorized	204,198,489	204,198,489
Redeemable convertible preferred stock, shares issued	202,009,981	202,009,981
Redeemable convertible preferred stock, shares outstanding	202,009,981	202,009,981
Redeemable convertible preferred stock, liquidation preference value		$ 128,922
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	300,000,000	266,833,885
Common stock, shares issued	19,470,914	755,478
Common stock, shares outstanding	19,470,914	755,478

Condensed Consolidated Statemen

Condensed Consolidated Statement of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Operating expenses:
Research and development	$ 6,076	$ 6,832	$ 10,174	$ 13,391
General and administrative	8,862	6,127	14,633	9,374
Total operating expenses	14,938	12,959	24,807	22,765
Loss from operations	(14,938)	(12,959)	(24,807)	(22,765)
Other (expense) income, net	(544)	36	(1,966)	84
Loss before income taxes	(15,482)	(12,923)	(26,773)	(22,681)
Provision (benefit) for income taxes	0	1	0	0
Net loss and comprehensive loss	(15,482)	(12,922)	(26,773)	(22,681)
Accretion on redeemable convertible preferred stock	0	128	129	256
Net loss attributable to common stockholders	$ (15,482)	$ (13,050)	$ (26,902)	$ (22,937)
Net loss per share attributable to common stockholders, basic and diluted	$ (1.10)	$ (35.88)	$ (3.60)	$ (63.32)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted	14,119,672	363,684	7,475,242	362,246

Condensed Consolidated Statem_2

Condensed Consolidated Statement of Changes in Redeemable Convertible Preferred Stock and Stockholders Deficit (Unaudited) - USD ($)	Total	Initial public offering	Redeemable Convertible Preferred Stock [Member]	Redeemable Convertible Preferred Stock [Member]Initial public offering	Common Stock	Common StockInitial public offering	Additional Paid-In Capital	Additional Paid-In CapitalInitial public offering	Accumulated Deficit
Beginning Balance at Dec. 31, 2019			$ 125,647,000
Beginning Balance, Shares at Dec. 31, 2019			201,335,862
Beginning Balance at Dec. 31, 2019	$ (91,704,000)						$ 760,000		$ (92,464,000)
Beginning Balance, Shares at Dec. 31, 2019					360,115
Accretion on preferred stock	128,000		$ 129,000				128,000
Stock-based compensation expense	298,000						298,000
Issuance of common stock upon the exercise of stock options	8,000						8,000
Issuance of common stock upon the exercise of stock options, Shares					3,569
Net loss and comprehensive loss	(9,759,000)								(9,759,000)
Ending Balance at Mar. 31, 2020			$ 125,776,000
Ending Balance, Shares at Mar. 31, 2020			201,335,862
Ending Balance at Mar. 31, 2020	(101,285,000)						938,000		(102,223,000)
Ending Balance, Shares at Mar. 31, 2020					363,684
Beginning Balance at Dec. 31, 2019			$ 125,647,000
Beginning Balance, Shares at Dec. 31, 2019			201,335,862
Beginning Balance at Dec. 31, 2019	(91,704,000)						760,000		(92,464,000)
Beginning Balance, Shares at Dec. 31, 2019					360,115
Conversion of convertible notes into common stock at initial public offering (in shares)	0
Net loss and comprehensive loss	(22,681,000)
Ending Balance at Jun. 30, 2020			$ 125,921,000
Ending Balance, Shares at Jun. 30, 2020			201,371,891
Ending Balance at Jun. 30, 2020	(111,850,000)						3,295,000		(115,145,000)
Ending Balance, Shares at Jun. 30, 2020					363,684
Beginning Balance at Mar. 31, 2020			$ 125,776,000
Beginning Balance, Shares at Mar. 31, 2020			201,335,862
Beginning Balance at Mar. 31, 2020	(101,285,000)						938,000		(102,223,000)
Beginning Balance, Shares at Mar. 31, 2020					363,684
Accretion on preferred stock	128,000		$ 127,000				128,000
Issuance of Series A-2 redeemable convertible preferred stock upon the exercise of preferred warrants			$ 18,000
Issuance of Series A-2 redeemable convertible preferred stock upon the exercise of preferred warrants (in shares)			36,029
Stock-based compensation expense	2,485,000						2,485,000
Net loss and comprehensive loss	(12,922,000)								(12,922,000)
Ending Balance at Jun. 30, 2020			$ 125,921,000
Ending Balance, Shares at Jun. 30, 2020			201,371,891
Ending Balance at Jun. 30, 2020	(111,850,000)						3,295,000		(115,145,000)
Ending Balance, Shares at Jun. 30, 2020					363,684
Beginning Balance at Dec. 31, 2020	$ 127,039,000		$ 127,039,000
Beginning Balance, Shares at Dec. 31, 2020	202,009,981		202,009,981
Beginning Balance at Dec. 31, 2020	$ (133,500,000)				$ 0		4,762,000		(138,262,000)
Beginning Balance, Shares at Dec. 31, 2020					755,478
Accretion on preferred stock	129,000		$ 129,000				129,000
Stock-based compensation expense	493,000						493,000
Issuance of common stock upon the exercise of stock options	18,000						18,000
Issuance of common stock upon the exercise of stock options, Shares					8,095
Net loss and comprehensive loss	(11,291,000)								(11,291,000)
Ending Balance at Mar. 31, 2021			$ 127,168,000
Ending Balance, Shares at Mar. 31, 2021			202,009,981
Ending Balance at Mar. 31, 2021	(144,409,000)				$ 0		5,144,000		(149,553,000)
Ending Balance, Shares at Mar. 31, 2021					763,573
Beginning Balance at Dec. 31, 2020	$ 127,039,000		$ 127,039,000
Beginning Balance, Shares at Dec. 31, 2020	202,009,981		202,009,981
Beginning Balance at Dec. 31, 2020	$ (133,500,000)				$ 0		4,762,000		(138,262,000)
Beginning Balance, Shares at Dec. 31, 2020					755,478
Conversion of convertible notes into common stock at initial public offering (in shares)	$ 8,393,000
Issuance of common stock upon the exercise of stock options, Shares	47,539
Net loss and comprehensive loss	$ (26,773,000)
Ending Balance at Jun. 30, 2021	$ 0		$ 0
Ending Balance, Shares at Jun. 30, 2021	202,009,981		0
Ending Balance at Jun. 30, 2021	$ 51,298,000				$ 19,000		216,314,000		(165,035,000)
Ending Balance, Shares at Jun. 30, 2021					19,470,914
Beginning Balance at Mar. 31, 2021			$ 127,168,000
Beginning Balance, Shares at Mar. 31, 2021			202,009,981
Beginning Balance at Mar. 31, 2021	(144,409,000)				$ 0		5,144,000		(149,553,000)
Beginning Balance, Shares at Mar. 31, 2021					763,573
Proceeds from initial public offering, net of underwriters' discounts and commissions	71,997,000				$ 5,000		71,992,000
Proceeds from initial public offering, net of underwriters' discounts and commissions, Shares					5,333,334
Issuance of common stock upon exercise of warrants for cash	377,000						377,000
Issuance of common stock upon exercise of warrants for cash (in shares)					23,887
Issuance of common stock upon net exercise of warrants upon initial public offering		$ 734,000						$ 734,000
Issuance of common stock upon net exercise of warrants upon initial public offering (in shares)						37,628
Issuance of common stock upon exchange of Avenue warrant	1,763,000						1,763,000
Issuance of common stock upon exchange of Avenue warrant (in shares)					107,663
Conversion of redeemable convertible preferred stock to common stock upon initial public offering		127,168,000		$ (127,168,000)		$ 13,000		127,155,000
Conversion of redeemable convertible preferred stock to common stock upon initial public offering, Shares				(202,009,981)		12,605,800
Conversion Of Convertible Notes Amount Converted At Initial Public Offering		$ 8,393,000				$ 1,000		$ 8,392,000
Conversion of convertible notes into common stock at initial public offering (in shares)						$ 559,585,000
Stock-based compensation expense	556,000						556,000
Issuance of common stock upon the exercise of stock options	201,000						201,000
Issuance of common stock upon the exercise of stock options, Shares					39,444
Net loss and comprehensive loss	(15,482,000)								(15,482,000)
Ending Balance at Jun. 30, 2021	$ 0		$ 0
Ending Balance, Shares at Jun. 30, 2021	202,009,981		0
Ending Balance at Jun. 30, 2021	$ 51,298,000				$ 19,000		$ 216,314,000		$ (165,035,000)
Ending Balance, Shares at Jun. 30, 2021					19,470,914

Condensed Consolidated Statem_3

Condensed Consolidated Statement of Changes in Redeemable Convertible Preferred Stock and Stockholders Deficit (Parenthetical) (Unaudited) $ in Millions	3 Months Ended
	Jun. 30, 2021USD ($)
Statement Of Stockholders Equity [Abstract]
Stock Issuance Cost	$ 2.4
Net Underwiters Discount And Commission	$ 5.6

Condensed Consolidated Statem_4

Condensed Consolidated Statement of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Cash flows from operating activities:
Net loss	$ (26,773)	$ (22,681)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	493	476
Stock-based compensation	1,049	2,783
Change in fair value of redeemable convertible preferred stock warrant liabilities	54	(80)
Change in Fair Value of Convertible Notes	839	0
Non Cash Interest	55	0
Amortization of debt discount	446	0
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(3,542)	(125)
Other assets	0	187
Accounts payable	1,070	607
Accrued liabilities	365	(113)
Net cash used in operating activities	(25,944)	(19,320)
Cash flows from investing activities:
Purchases of property and equipment	(116)	(818)
Net cash used in investing activities	(116)	(818)
Cash flows from financing activities:
Proceeds from initial public offering, net of issuance costs	71,997	0
Proceeds from the issuance of convertible notes	7,500	0
Proceeds From Exercise of Redeemable Convertible Preferred Stock Warrants	197	18
Proceeds from issuance of common stock upon exercise of stock options	219	8
Net cash provided by financing activities	79,913	26
Net increase (decrease) in cash	53,853	(20,112)
Cash — Beginning of period	7,095	37,001
Cash — End of period	60,948	16,889
Supplemental disclosures of cash flow information:
Accretion to redemption value on redeemable convertible preferred stock	129	256
Conversion of redeemable convertible preferred stock upon initial public offering	127,168	0
Issuance of common stock upon exchange / exercise of redeemable convertible preferred stock warrants upon initial public offering	2,677	0
Conversion of convertible notes into common stock upon initial public offering	8,393	0
Purchase of Property and Equipment Inluded in Accounts Payable and Accrued Liabilities	$ 84	$ 145

Organization and Description of

Organization and Description of Business	6 Months Ended
	Jun. 30, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Description of Business	1. Organization and Description of Business Impel Neuropharma, Inc. (“the Company”), is a late-stage is a late-stage pharmaceutical company focused on the development and commercialization of transformative therapies for patients suffering from diseases with high unmet medical needs, with an initial focus on diseases of the central nervous system, or CNS. The Company’s strategy is to pair its proprietary Precision Olfactory Delivery, or POD, upper nasal delivery technology with well-understood therapeutics or other therapeutics where rapid vascular absorption is preferred to drive therapeutic benefit, improve patient outcomes, reduce drug development risk and expand the commercial opportunity within its target diseases. The Company was incorporated under the laws of the State of Delaware on July 24, 2008 , maintains its headquarters and principal operations in Seattle, Washington, and performs certain of its research and development activities in Australia. Initial Public Offering On April 22, 2021, the Company’s Registration Statement on Form S-1 relating to its initial public offering, or IPO, was declared effective by the Securities and Exchange Commission, or the SEC, and the shares of its common stock began trading on the Nasdaq Global Select Market on April 23, 2021. The IPO closed on April 27, 2021, pursuant to which the Company issued and sold 5,333,334 shares of its common stock at a public offering price of $ 15.00 per share. The Company received net proceeds of approximately $ 72.0 million from the IPO, after deducting underwriting discounts and commissions of $ 5.6 million and offering costs of $ 2.4 million. Prior to the completion of the IPO, all shares of redeemable convertible preferred stock then outstanding were converted into 12,605,800 shares of common stock. In addition, the warrant held by Avenue Venture Opportunities Fund, L.P., or Avenue, was exchanged for 107,663 shares of common stock and warrants to purchase 1,987,348 shares of redeemable convertible preferred stock were cash exercised or automatically net exercised into an aggregate of 61,515 shares of common stock. The convertible notes issued in March 2021 for an aggregate principal amount of $ 7.5 million (see Note 6) were also converted into 559,585 shares of common stock at a 10 % discount of the IPO price. Reverse Stock Split In April 2021, the Company’s board of directors and stockholders approved an amendment to the Company’s certificate of incorporation to effect a reverse split of shares of the Company’s common stock on an one-for-16.37332 basis, which was effected on April 16, 2021 (the “Reverse Stock Split”). The number of authorized shares and the par values of the common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. In connection with the Reverse Stock Split, the conversion ratio for the Company’s outstanding redeemable convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split. All references to common stock and options to purchase common stock share data, per share data and related information contained in the condensed consolidated financial statements have been retroactively adjusted to reflect the effect of the Reverse Stock Split for all periods presented. Liquidity and Capital Resources The Company raised $ 72.0 million in net proceeds from its IPO in April 2021 and from the Company’s inception through June 30, 2021, it raised an aggregate of $ 214.5 million in gross cash proceeds from the IPO, sale and issuance of redeemable convertible preferred stock, convertible notes, debt and warrants. The Company had a cash and cash equivalents balance of $ 60.9 million as of June 30, 2021. Based upon the Company’s current operating plan, it estimates that its cash and cash equivalents as of June 30, 2021, are together sufficient for the Company to fund operating, investing, and financing cash flow needs for at least one year from the issuance date of these interim financial statements. On July 2, 2021, the Company entered into a loan and security agreement with Oxford Finance LLC (“Oxford”), as the collateral agent and a lender, and Silicon Valley Bank (“SVB”), as a lender to potentially borrow up to an aggregate principal amount of $ 50.0 million in a series of term loans (see Note 14). In the event of an FDA approval, the Company may be required to raise additional capital to meet working capital needs associated with commercialization. If sufficient funds on acceptable terms are not available when needed, the Company could be required to reduce operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs or planned product launch plans. Failure to manage discretionary spending or raise additional financing, as needed, may adversely impact the Company’s ability to achieve its intended business objectives. 9

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 and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or U.S. GAAP. The condensed consolidated financial statements include the operations of Impel Neuropharma, Inc., and its wholly owned Australian subsidiary. All intercompany balances and transactions have been eliminated upon consolidation. The condensed consolidated balance sheet as of June 30, 2021, the condensed consolidated statements of operations and comprehensive loss, changes in redeemable convertible preferred stock and stockholders’ equity (deficit) and cash flows for the three and six months ended June 30, 2021 and 2020 are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of June 30, 2021 and its results of operations and cash flows for the three and six months ended June 30, 2021 and 2020. The financial data and the other financial information contained in these notes to the condensed consolidated financial statements related to the three and six month periods are also unaudited. The results of operations for the three months and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2020 included herein was derived from the audited financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in the prospectus dated April 23, 2021 that forms a part of the Company's Registration Statement on Form S-1 (File No. 333-254999), as filed with the SEC pursuant to Rule 424(b)(4) promulgated under the Securities Act of 1933, as amended. Reclassifications We have reclassified prior period financial statements to conform to the current period presentation. During the six months ended 2021, we reclassified certain amounts previously recorded as general and administrative expense to research and development expense. Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates such estimates and assumptions for continued reasonableness. In particular, management makes estimates with respect to the fair values of common stock, redeemable convertible preferred stock warrant liabilities, stock-based compensation expense, convertible debt and income taxes. Appropriate adjustments, if any, to the estimates used are made prospectively based upon such periodic evaluation. Actual results could differ from those estimates. Segments The Company’s chief operating decision maker is its Chief Executive Officer. The Chief Executive Officer reviews financial information on an aggregate basis for the purposes of evaluating financial performance and allocating the Company’s resources. Accordingly, the Company has determined that it operates in one segment. Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. At June 30, 2021 and December 31, 2020, cash consisted of cash in bank deposits held at financial institutions. Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash. The Company’s cash is deposited with high credit quality financial institutions. At times such deposits may be in excess of the Federal Depository Insurance Corporation insured limits. Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reflected in the accompanying consolidated balance sheets for cash, other current assets, accounts payable, and accrued liabilities approximate their fair values, due to their short-term nature. Convertible Notes In March 2021, the Company issued convertible promissory notes to various investors for an aggregate amount of $7.5 million. As permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), the Company has elected the fair value option for recognition of the convertible notes. The Company elected the fair value option to allow the Company to eliminate the burden of complying with the requirements for derivative accounting. Under the fair value option, the convertible notes are remeasured at fair value in each reporting period until their conversion in April 2021, with changes in the fair value recognized in the Company’s condensed consolidated statement of operations as other (expense) income, net. Accrued interest on the convertible notes is recorded in other (expense), net. Deferred Offering Costs The Company incurred offering costs consisting of legal, accounting and other fees and costs directly attributable to the Company’s IPO. As of June 30, 2021, $ 2.4 million of deferred offering costs were charged to additional paid-in capital upon the completed of the IPO in April 2021. There were no deferred offering costs as of December 31, 2020 . Redeemable Convertible Preferred Stock Warrant Liabilities Freestanding warrants to purchase shares of the Company’s redeemable convertible preferred stock are accounted for as liabilities at fair value through the date of exercise, because the shares underlying the warrants contain contingent redemption features outside the control of the Company. Warrants classified as liabilities are recorded on the Company’s condensed consolidated balance sheets at their fair value on the date of issuance and remeasured to fair value each subsequent reporting period, with the changes in fair value recognized as a component of other (expense) income, net in the accompanying condensed consolidated statements of operations. The Company adjusted the liability for the final change in the fair value of these warrants immediately preceding their automatic exercise in connection with the IPO. Upon exercise, the corresponding liability was reclassified to additional paid-in capital. Research and Development Research and development costs are expensed as incurred and consist primarily of salaries, benefits and other staff-related costs, including associated stock-based compensation, laboratory supplies, nonclinical and clinical studies and trials and related clinical manufacturing costs, costs related to manufacturing preparation, fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed. Such payments are evaluated for current or long-term classification based on when such services are expected to be received. Advance Payments for Research and Development Services and Accruals As part of the process of preparing its condensed consolidated financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its condensed consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines advance payments for research and development services and accrual estimates through discussion with applicable personnel and outside service providers as to the progress of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its advance payments and accrued expenses as of each balance sheet date in its condensed consolidated financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2021, there had been no material adjustments to the Company’s prior period estimates of advance payments and accruals for research and development expenses. The Company’s research and development advance payments and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors. Stock-Based Compensation The Company recognizes stock-based compensation expense for stock options and restricted stock unit awards on a straight-line basis over the requisite service period. The Company’s stock-based compensation costs are based upon the grant date fair value of options estimated using the Black-Scholes-Merton option pricing model. This model utilizes as inputs the estimated fair value of the underlying common stock at the measurement date, the estimated term of the stock options (weighted-average period of time that the options granted are expected to be outstanding), risk-free interest rates, expected dividends, and the expected volatility of the Company’s common stock. The Company has elected to recognize forfeitures of share-based payment awards as they occur. The Company recognizes stock-based compensation expense for stock options granted to non-employees based on the estimated fair value of the award as it is more readily measurable than the fair value of the services received. Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potentially dilutive securities. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since the effect of potentially dilutive securities is anti-dilutive given the net loss of the Company. Comprehensive Loss Comprehensive loss represents the change in the Company’s stockholders’ equity (deficit) from all sources other than investments by or distributions to stockholders. The Company has no items of other comprehensive loss; as such, net loss equals comprehensive loss. Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases , or Topic 842, which supersedes the guidance in former ASC 840, Leases . This standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less may be accounted for similar to existing guidance for operating leases today. In May 2020, the FASB issued ASU No. 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities, which deferred the effective dates for non-public entities. Therefore, this standard is effective for annual reporting periods, and interim periods within those years, for public entities beginning after December 15, 2018 and for private entities beginning after December 15, 2021. Originally, a modified retrospective transition approach was required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued guidance to permit an alternative transition method for Topic 842, which allows transition to the new lease standard by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Entities may elect to apply either approach. There are also a number of optional practical expedients that entities may elect to apply. The Company is currently assessing the impact of this standard on its condensed consolidated financial statements. The Company expects to record a material right-of-use asset and lease liability in connection with adopting this standard on January 1, 2022. Recently Adopted Pronouncements In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , or ASU 2020-06, which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020 and adoption must be as of the beginning of the Company’s annual fiscal year. The Company early adopted this standard on January 1, 2021 and the adoption of the standard did not have a significant impact on its consolidated financial statements.

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 table summarizes the fair value of the Company’s financial liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Liabilities: Redeemable convertible preferred stock warrant liabilities $ — $ — $ 2,622 $ 2,622 Total financial liabilities $ — $ — $ 2,622 $ 2,622 There were no financial liabilities as of June 30, 2021 that were measured at fair value. The following table summarizes the change in the fair value of the redeemable convertible preferred stock warrant liabilities for the six months ended June 30, 2021 (in thousands): Beginning balance as of December 31, 2020 $ 2,622 Losses from changes in fair value 55 Settlement upon IPO ( 2,677 ) Ending balance as of June 30, 2021 $ — The following table summarizes the change in the fair value of the convertible notes for the six months ended June 30, 2021 (in thousands): Beginning balance as of December 31, 2020 $ — Issuance of convertible notes 7,500 Interest 54 Losses from changes in fair value 839 Conversion upon IPO ( 8,393 ) Ending balance as of June 30, 2021 $ — Fair values of the Company’s redeemable convertible preferred stock warrant liabilities and convertible notes are based on significant inputs not observed in the market, and thus represent a Level 3 measurement. Refer to Note 6 and Note 7 for the valuation techniques and assumptions used in estimating the fair value of the convertible notes and warrants, respectively.

Balance Sheet Components

Balance Sheet Components	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Balance Sheet Components	4. Balance Sheet Components Prepaid Expenses and Other Current Assets Prepaid expenses and other current assets consisted of the following (in thousands): June 30, December 31, Refundable clinical deposits $ 337 $ 672 Tax refund receivable 25 229 Prepaid insurance 3,050 47 Other prepaids and current assets 1,207 129 Total prepaid expenses and other current assets $ 4,619 $ 1,077 Accrued Liabilities Accrued liabilities consisted of the following (in thousands): June 30, December 31, Accrued professional services $ 1,340 $ 192 Accrued compensation 1,986 2,393 Accrued other liabilities 214 333 Accrued construction in progress 6 255 Total accrued liabilities $ 3,546 $ 3,173

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	5. Commitments and Contingencies Operating Leases The Company leases office and laboratory space in Seattle, Washington. In September 2017, the Company entered into a non-cancelable operating lease for 11,256 square feet of office and laboratory space. Rent is payable monthly, increasing by approximately 3 % each year. As of June 30, 2021, the remaining future minimum lease payments were $ 0.8 million through the expiration date of August 31, 2022 . Rent expense for the three months and six months ended June 30, 2021 was $ 175,000 and $ 349,000 , respectively and for the three and six months ended June 30, 2020 was $ 188,000 and $ 344,000 respectively. Legal Proceedings From time to time, the Company may have certain contingent liabilities that arise in the ordinary course of its business activities. The Company accrues a liability for such matters when it is probable that future expenditures will be made and that such expenditures can be reasonably estimated. Significant judgment is required to determine both probability and the estimated amount. Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions. The Company intends to enter into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by Delaware corporate law. The Company currently has directors’ and officers’ insurance coverage that reduces its exposure and enables the Company to recover a portion of any future amounts paid. The Company believes the estimated fair value of these indemnification agreements in excess of applicable insurance coverage is minimal. COVID-19 In March 2020, the COVID-19 disease was declared a pandemic by the World Health Organization. Management continues to evaluate the potential impacts of the COVID-19 pandemic on the development of its product candidates, and business. The Company is working closely with its manufacturing vendors to maintain adequate product supply and with healthcare providers as future studies are planned to mitigate risk to patients while adhering to regulatory, institutional and government guidance and policies. The Company remains committed to its development plans and acknowledges the potential risk for delays in the product supply chain and in anticipated timelines for its preclinical studies and clinical trials.

Debt

Debt	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Debt	6. Debt Term Loan On November 5, 2020 the Company entered into a debt and equity financing agreement with Avenue Venture Opportunities Fund, L.P., ( “Avenue”). The agreement provides for a 36-month term loan of up to $ 20.0 million, of which $ 10.0 million was funded at close and (b) an additional $ 10.0 million is available at the Company’s request until December 31, 2021, subject to (i) completion of an underwritten public offering with gross proceeds of at least $ 75.0 million, or a Qualified Offering, (ii) receipt of FDA approval of TRUDHESA and (iii) approval by Avenue’s investment committee. The term loan bears interest at the higher of the prime rate or 11 %. Payments for the term loan were initially interest only for the initial 12 months, extended to 24 months upon closing of our IPO, and can be extended to 36 months upon FDA approval of TRUDHESA. The term loan will amortize in equal payments of principal from the end of the interest only period to the expiration of the 36-month term on November 1, 2023 and includes a final payment of $ 450,000 due upon the maturity of the term loan. In connection with the agreement, the Company granted Avenue warrants for the purchase of shares of 1,762,810 shares of Series D redeemable convertible preferred stock, as disclosed in Note 7. The Company’s obligations are secured by a security interest in substantially all of the Company’s assets, excluding the. Company’s intellectual property. The agreement contains customary representations, warranties and covenants, including covenants by the Company limiting additional indebtedness, liens, including on intellectual property, guaranties, mergers and consolidations, substantial asset sales, investments and loans, certain corporate changes, transactions with affiliates and fundamental changes. The agreement provides for events of default customary for term loans of this type, including but not limited to non-payment, breaches or defaults in the performance of covenants, insolvency and bankruptcy. The net proceeds from the issuance of the term loan were initially allocated to the warrants at an amount equal to their fair value of $ 1.5 million and the remainder to the term loan. The Company incurred financing costs of $ 299,000 which, together with the fair value of the warrants and the final payment, are recorded as a debt discount and are being amortized over the contractual term using the effective interest method. During the three and six months ended June 30, 2021, the Company incurred interest expense of $ 509,000 and $ 999,000 , respectively and is classified as other (expense) income. The estimated fair value of the Avenue term loan, as of June 30, 2021 was $11.0 million, compared to the principal amount outstanding of $10.45 million. The estimated fair value was based on borrowing rates available to the Company for loans with similar terms and consideration of the Company’s credit risk, as such, the Company’s long-term debt was classified within Level 3 of the fair value hierarchy. The term loan consists of the following (in thousands): June 30, December 31, Face value of term loan $ 10,000 $ 10,000 Final payment 450 450 Unamortized debt discount associated with final payment, ( 1,593 ) ( 2,039 ) Total debt, net $ 8,857 $ 8,411 Less: short-term debt — 417 Long-term debt $ 8,857 $ 7,994 As described in Notes 1 and 14 of these financial statements, on July 2, 2021, the Company entered into a loan and security agreement (the “Agreement”) with Oxford and SVB (together with Oxford, the “Lenders”), to borrow up to an aggregate principal amount of $50.0 million in a series of term loans. Upon entering into the Agreement, the Company borrowed $ 20.0 million from the Lenders with approximately $ 10.8 million of such amount applied to the repayment of outstanding principal, interest and final payment fees owed under the debt and equity financing agreement with Avenue. As a result, the total debt, net has been classified on our balance sheet as Long-term debt – non-current as of June 30, 2021. Convertible Promissory Notes In March 2021, the Company issued unsecured convertible promissory notes to various investors for an aggregate amount of $ 7.5 million which were accounted for at fair value. The notes bore interest at a rate of 5.0 % per annum and mature on the earlier of (a) December 31, 2021 and (b) a change of control. The notes were automatically converted into shares of the Company’s common stock upon the closing of the IPO. The agreement contained customary representations, warranties and covenants, including covenants by the Company limiting additional indebtedness, liens, including on intellectual property, guaranties, mergers and consolidations, substantial asset sales, investments and loans, certain corporate changes, transactions with affiliates and fundamental changes. The agreement provided for events of default customary for term loans of this type, including but not limited to non-payment, breaches or defaults in the performance of covenants, insolvency and bankruptcy. On March 31, 2021, the notes were remeasured to their settlement amount at the IPO date excluding accrued interest due to the proximity of the settlement date to the end of the reporting period. The loss on the increase in fair value on the convertible notes totaled $839,000 from their issuance through June 30, 2021 and is classified as other (expense) income, net in the accompanying condensed consolidated statements of operations. For the three and six months ended June 30, 2021, interest expense incurred in connection with the convertible promissory notes was $27,000 and $54,000, respectively and is classified as other (expense) income.. The carrying value of the convertible notes of $ 8.4 million immediately prior to the Company’s IPO subsequently converted into 559,585 shares of common stock upon completion of the IPO.

Redeemable Convertible Preferre

Redeemable Convertible Preferred Stock Warrant Liabilities	6 Months Ended
	Jun. 30, 2021
Warrants And Rights Note Disclosure [Abstract]
Redeemable Convertible Preferred Stock Warrant Liabilities	7. Redeemable Convertible Preferred Stock Warrant Liabilities The key terms of the redeemable convertible preferred stock warrant liabilities as of December 31, 2020 are summarized in the following table: Number of shares as of Exercisable into: June 30, December 31, Exercise Expiration Series A-2 redeemable convertible preferred stock — 862,471 $ 0.4996 September 30, 2021 Series C-1 redeemable convertible preferred stock — 1,124,877 0.5289 November 16, 2021 Series D redeemable convertible preferred stock — 1,762,810 0.7091 October 31, 2021 Total — 3,750,158 The fair value of the warrants was determined using an option pricing model. Under this model, the estimated equity value of the Company as of the measurement date was allocated to various classes of financial instruments (such as common and redeemable convertible preferred stock and warrants to purchase redeemable convertible preferred stock) based on their rights and preferences in an assumed liquidity scenario, which was estimated to occur in two years. Other assumptions used prior to the IPO included stock volatility ranging from 46.4 % to 103.0 % and risk-free interest rates ranging from 0.04 % to 0.24 % during the three months ended March 31, 2021. In April 2021, upon completion of the IPO, the Series A-2 and C-1 redeemable convertible preferred stock warrants were cash or net exercised into an aggregate of 61,515 shares of common stock. The Series D redeemable convertible preferred stock warrants were exchanged for 107,663 shares of common stock.

Redeemable Convertible Prefer_2

Redeemable Convertible Preferred Stock	6 Months Ended
	Jun. 30, 2021
Temporary Equity Disclosure [Abstract]
Redeemable Convertible Preferred Stock	8. Redeemable Convertible Preferred Stock Redeemable convertible preferred stock consisted of the following (in thousands, except share amounts) as of December 31, 2020: Redeemable Convertible Shares Authorized Shares Issued and Carrying Value at Aggregate Series A-1 746,426 746,426 $ 238 $ 305 Series A-2 9,869,218 8,805,587 4,147 4,399 Series B 3,968,775 3,968,775 3,980 4,421 Series C-1 43,278,699 42,153,822 20,975 22,297 Series C-2 26,537,826 26,537,826 15,390 15,000 Series C-3 24,605,790 24,605,790 14,973 15,000 Series D 95,191,755 95,191,755 67,336 67,500 Total 204,198,489 202,009,981 $ 127,039 $ 128,922 Classification The Company classified its redeemable convertible preferred stock as mezzanine equity on the condensed consolidated balance sheets as the shares were contingently redeemable with passage of time or upon deemed liquidation events, such as a change in control. As only the passage of time is required for Series B, C-1, C-2, C-3, and D preferred stock to become redeemable, the Company is accreting the carrying value of the preferred stock shares to their redemption value, using the effective interest method, over the period from issuance to the earliest payment dates. With respect to Series A-1 and A-2, no accretion was recorded during the six months ended June 30, 2021 and 2020, as a deemed liquidation event was no t probable. Amounts recorded for the accretion of redeemable convertible preferred stock during the six months ended June 30, 2021 and 2020 were $ 129,000 and $ 256,000 , respectively. The accretion is recorded as a deemed dividend and a charge to additional paid-in capital. In April 2021, immediately prior to the completion of the IPO (see Note 1), all outstanding shares of redeemable convertible preferred stock were automatically converted into 12,605,800 shares of common stock. Upon conversion into common stock, the carrying value of the redeemable convertible preferred stock of $ 127.2 million was reclassified to equity.

Common Stock

Common Stock	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Common Stock	9. Common Stock Each share of common stock has the right to one vote. The holders of common stock are also entitled to receive dividends whenever funds are legally available and when declared by the board of directors, subject to the prior rights of holders of all classes of stock outstanding having priority rights as to dividends. No cash dividends have been declared by the board of directors from inception. The Company has reserved the following shares of common stock for issuance, on an as-converted basis, as follows: June 30, December 31, Stock incentive plans 5,219,804 2,786,345 Redeemable convertible preferred stock — 12,605,800 Convertible notes — — Redeemable convertible preferred stock warrants — 229,034 Total 5,219,804 15,621,179

Stock Incentive Plan

Stock Incentive Plan	6 Months Ended
	Jun. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plan	10. Stock Incentive Plan 2021 Equity Incentive Planpolicies The Company adopted its 2021 Stock Incentive Plan, or the 2021 Plan, and the Employee Stock Purchase Plan, or the ESPpoliciesP, which became effective on the date immediately prior to the date of effectiveness of the IPO. The 2021 Plan serves as the successor to its 2018 Equity Incentive Plan (the “2018 Plan”). The 2021 Plan authorizes the award of stock options, RSUs, restricted stock awards, stock bonus awards, stock appreciation rights, performance awards, and cash awards. The Company initially reserved 2,205,000 shares of its common stock for the 2021 Plan, plus any reserved shares not issued or subject to outstanding grants under the 2018 Plan on the effective date of the 2021 Plan, for issuance pursuant to awards granted under its 2021 Plan. The total number of shares reserved for issuance under the 2021 Plan upon its effective date is 2,272,613 shares The number of Shares available for issuance under the 2021 Plan will increase automatically on January 1 of each of 2022 through 2031 by the lesser of (a) 5 % of the total number of outstanding shares of all classes of its common stock on each December 31 st and (b) a number as may be determined by its board of directors. The Company has reserved 276,000 shares of its common stock for the 2021 Employee Stock Purchase Plan. At June 30,2021, options to purchase 131,621 shares under the 2021 plan remained outstanding. 2008 Plan In September 2008, the Company’s board of directors adopted the 2008 Stock Incentive Plan, or the 2008 Plan, which provides for the granting of incentive stock options, nonqualified stock options, and restricted stock awards to its employees, directors and consultants. Options granted or shares issued under the 2008 Plan that were outstanding on the date the 2018 Equity Incentive Plan, or the 2018 Plan, became effective will remain subject to the terms of the 2008 Plan. The 2008 Plan terminated in 2018 as it reached its ten-year term. At June 30, 2021 and December 31, 2020, options to purchase 604,267 and 634,788 shares, respectively, under the 2008 plan remained outstanding. 2018 Plan In November 2018, the Company’s board of directors adopted the 2018 Equity Incentive Plan. The 2018 Plan provides for the granting of incentive stock options, nonqualified stock options, restricted stock units, and other forms of stock awards to its employees, directors and consultants. Under the 2018 Plan, the Company initially reserved 753,645 shares of common stock for issuance. In addition, any authorized shares not issued or subject to outstanding grants under the 2008 Plan and any shares subject to outstanding stock options that are cancelled without being exercised or expire under the 2008 Plan were added to the shares authorized and reserved for issuance under the 2018 Plan. In connection with the Board of Directors approval of the 2021 Plan, all remaining shares available for future award under the 2018 Plan were transferred to the 2021 Plan. At June 30, 2021 and December 31, 2020, options to purchase 2,034,734 and 1,807,101 shares, respectively, under 2018 Plan remained outstanding. Stock Option Activity A summary of the Company’s stock option activity under its stock option plans was as follows (in thousands, except share and per share data and years): Options Outstanding Shares Number of Weighted Remaining Aggregate Balance — December 31, 2020 344,456 2,441,889 $ 5.17 8.02 $ 14,844 Authorized 2,205,000 — Granted ( 408,464 ) 408,464 $ 12.39 Exercised — ( 47,539 ) $ 4.61 Cancelled 32,029 ( 32,059 ) $ 4.86 Balance — June 30, 2021 2,173,021 2,770,755 $ 6.25 7.87 $ 8,600 Exercisable — June 30, 2021 — 1,316,271 $ 4.00 6.88 $ 6,388 In May 2020, the Company’s board of directors increased the pool of stock options available for future grant by 596,414 shares and appointed an existing member of the board of directors as the Company’s Chief Executive Officer. In connection with this change, the Company granted 715,358 stock options to its Chief Executive Officer at an exercise price of $ 7.86 per share that will vest ratably over 48 months . Vesting of the Chief Executive Officer’s options accelerate upon a termination without cause. In the second quarter 2020, the Company recognized $ 2.1 million of expense related to a modification upon the acceleration of the former Chief Executive Officer’s outstanding options upon his departure from the Company. The total intrinsic value of options exercised was $ 202,000 and $ 26,000 during the six months ended June 30, 2021 and 2020, respectively. The intrinsic value is the difference between the estimated fair value of the Company’s common stock at the time of exercise, as determined by the board of directors, and the exercise price of the stock option. The total fair value of options that vested during the six months ended June 30, 2021 and 2020 was $ 1.3 million and $ 0.9 million, respectively. The grant date fair value of options granted during the six months ended June 30, 2021 and 2020 was $ 3.8 million and $ 2.9 million, respectively. The weighted-average grant date fair value of employee options granted during the six months ended June 30, 2021 and 2020 was $ 7.22 and $ 4.42 per share, respectively. Stock-Based Compensation Expense Stock-based compensation expense recognized was as follows (in thousands): Three Months Ended Six Months Ended 2021 2020 2021 2020 Research and development $ 437 $ 2,360 $ 811 $ 2,539 General and administrative 119 125 238 244 Total stock-based compensation expense $ 556 $ 2,485 $ 1,049 $ 2,783 As of June 30, 2021, there was $ 5.0 million of total unrecognized compensation cost related to unvested options that are expected to vest. The cost is expected to be recognized over a weighted-average period of 2.8 years. In determining the fair value of the stock options granted, the Company uses the Black-Scholes-Merton option-pricing model and assumptions discussed below. Each of these inputs is subjective. Fair Value of Common Stock— Prior to the IPO, given the absence of a public trading market, the Company’s board of directors with input from management considered numerous objective and subjective factors to determine the fair value of common stock. The factors included, but were not limited to: (1) third-party valuations of the Company’s common stock; (2) the Company’s stage of development; (3) the status of research and development efforts; (4) the rights, preferences and privileges of the Company’s preferred stock relative to those of the Company’s common stock; (5) the Company’s operating results and financial condition, including the Company’s levels of available capital resources; and (6) equity market conditions affecting comparable public companies; (7) general U.S. market conditions; and (8) the lack of marketability of the Company’s common stock. Expected Term —The Company’s expected term represents the period that the Company’s stock-based awards are expected to be outstanding. The Company used the simplified method (based on the mid-point between the vesting date and the end of the contractual term) to determine the expected term. Expected Volatility —Since the Company recently completed its IPO and does not have substantial trading history for its common stock, the expected volatility was estimated based on the average historical volatilities for comparable publicly traded pharmaceutical companies over a period equal to the expected term of the stock option grants. The comparable companies were chosen based on their similar size, stage in the life cycle and area of specialty. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of option. Expected Dividend —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero . The fair value of stock option awards granted to employees was estimated at the date of grant using a Black-Scholes-Merton option pricing model with the following assumptions: Three Months Ended Six Months Ended 2021 2020 2021 2020 Expected term (in years) 6.1 6.1 6.1 6.1 Expected volatility 59.2 - 85.5 % 56.4 - 57.6 % 59.2 - 85.5 % 56.4 - 57.6 % Risk-free interest rate 0.79 - 0.86 % 0.41 - 0.50 % 0.42 - 0.92 % 0.41 - 1.55 % Expected dividends — — — —

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes To calculate the interim tax provision, at the end of each interim period the Company estimates the annual effective tax rate and applies that to its quarterly earnings from continuing operations. The effect of changes in the enacted tax laws or rates is recognized in the interim period in which the change occurs. The computation of the annual estimated effective tax rate at each interim period requires certain estimates and judgments including, but not limited to, the expected operating income for the year, projections of the proportion of income earned and taxed in foreign jurisdictions, permanent differences between book and tax amounts, and the likelihood of recovering deferred tax assets generated in the current year. The accounting estimates used to compute the provision for income taxes may change as new events occur, additional information is obtained, or the tax environment changes. The Company’s effective tax rate for the six months ended June 30, 2021 and 2020 differs from the U.S. statutory rate due to the U.S. valuation allowance and foreign income taxed at local statutory rates. During the three and six months ended June 30, 2021, the Company reported U.S. pre-tax losses, consistent with prior years to date. The Company has not yet been able to establish a sustained level of profitability in the U.S. or other sufficient significant positive evidence to conclude that its U.S. deferred tax assets are more likely than not to be realized. Therefore, the Company continues to maintain a valuation allowance against its U.S. deferred tax assets.

Defined Contribution Plan

Defined Contribution Plan	6 Months Ended
	Jun. 30, 2021
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	12. Defined Contribution Plan The Company has a defined contribution retirement savings plan under Section 401(k) of the IRC. This plan allows eligible employees to defer a portion of their annual compensation on a pre-tax or after-tax basis. The Company makes discretionary matching contributions of up to 4 % of a participating employee’s salary. For the three and six months ended June 30, 2021 and 2020, the amount expensed under the plan was $ 70,000 and $ 181,000 respectively. For the three and six months ended June 30, 2020, the amount expensed under the plan was $ 62,000 and $ 157,000 , respectively.

Net Loss Per Share Attributable

Net Loss Per Share Attributable to Common Stockholders	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Net Loss Per Share Attributable to Common Stockholders	13. Net Loss Per Share Attributable to Common Stockholders The following outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share attributable to common stockholders for the periods presented because their effect would have been anti-dilutive: Six Months Ended 2021 2020 Redeemable convertible preferred stock on an as-converted basis — 12,541,308 Redeemable convertible preferred stock warrants on an as-converted basis — 160,349 Convertible notes on an as-converted basis — — Stock options to purchase common stock 2,770,785 3,033,481 Total 2,770,785 15,735,138

Subsequent Events

Subsequent Events	6 Months Ended
	Jun. 30, 2021
Subsequent Events [Abstract]
Subsequent Events	14. Subsequent Events On July 2, 2021, the Company entered into the Agreement with Oxford, as the collateral agent and a lender, and SVB, as a lender, pursuant to which the Lenders have agreed to lend the Company up to an aggregate of $50.0 million in a series of term loans (the “Term Loan”). Upon entering into the Agreement, the Company borrowed $20.0 million from the Lenders (the “Term A Loan”), with approximately $10.8 million of such amount applied to the repayment of the outstanding principal, interest and final payment fees owed pursuant to the Company’s prior loan and security agreement with Avenue dated November 5, 2020. Upon termination of the loan and security agreement with Avenue, the Company expects to record a loss on the early extinguishment of debt related to the unamortized debt discount associated with the fair value of the warrants, final payment fee, and unamortized debt issuance costs. Under the terms of the Agreement, the Company may, at its sole discretion, borrow from the Lenders up to an additional $ 10.0 million (the “Term B Loan”) upon the achievement by the Company of NDA approval from the FDA of TRUDHESA, as determined by Oxford in its sole and absolute discretion (the “Term B Milestone Event”). The Company may draw the Term B Loan during the period commencing on the date of the occurrence of the Term B Milestone Event and ending on the earliest of (i) September 30, 2021 (ii) the sixtieth (60th) day following the occurrence of the Term B Milestone Event, and (iii) the occurrence of an event of default. Under the terms of the Agreement, the Company may, at its sole discretion, borrow from the Lenders up to an additional $ 20.0 million (the “Term C Loan”) upon the achievement by the Company of net revenue for a trailing six (6) month period of at least $ 15,000,000 , as determined by Oxford in its sole and absolute discretion (the “Term C Milestone Event”). The Company may draw the Term C Loan during the period commencing on the date of the occurrence of the Term C Milestone Event and ending on the earliest of (i) December 31, 2022 (ii) the sixtieth (60th) day following the occurrence of the Term C Milestone Event, and (iii) the occurrence of an event of default. The proceeds from the Term Loans under the Agreement may be used to satisfy the Company’s future working capital needs and to fund its general business requirements. The Company’s obligations under the Agreement are secured by all assets of the Company, other than its intellectual property. The Company has also agreed not to encumber its intellectual property assets, except as permitted by the Agreement. All of the Term Loans mature on July 1, 2026 (the “Maturity Date”) and will be interest-only through September 1, 2023, provided however, that following Company’s achievement of the Term C Milestone Event by not later than December 31, 2022, the Term Loans will be interest-only through September 1, 2024, followed by 35 equal monthly payments of principal and interest, provided, however, that following Company’s achievement of the Term C Milestone Event by no later than December 31, 2022, such number of months shall be automatically reduced to 23 consecutive months. The Term Loans will bear interest at a floating per annum rate equal to the greater of (i) 7.95% or (ii) the sum of (a) the greater of (1) the thirty (30) day U.S. LIBOR rate reported in the Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue or (2) 0.11%, plus (b) 7.84%. The Company will be required to make a final payment of 6.5 % of the original principal amount of the Term Loans drawn, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of any Term Loans, or (iii) the prepayment of the Term Loans (the “Final Payment”). The Company may prepay all, but not less than all, of the Term Loans upon 30 days’ advance written notice to Oxford, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3.0% of the principal amount of the applicable Term Loan prepaid on or before the first anniversary of the applicable funding date, (ii) 2.0% of the principal amount of the applicable Term Loan prepaid between the first and second anniversary of the applicable funding date, and (iii) 1.0% of the principal amount of the applicable Term Loan prepaid thereafter, and prior to the Maturity Date (each, a “Prepayment Fee”). In connection with entering into the Agreement and borrowing the Term A Loan, the Company issued to the Lenders warrants exercisable for an aggregate of 71,522 shares of the Company’s common stock (the “Warrants”). The Warrants are exercisable in whole or in part, immediately, and have a per share exercise price of $ 8.389 , which is the 10-trading day trailing average closing price prior to the date of the Term A Loan funding. The Warrants will terminate on the earlier of July 2, 2031 or the closing of certain merger or consolidation transactions. If the Company borrows additional Term Loans under the Agreement, the Company will be required to issue to the Lenders additional warrants exercisable for a number of shares of the Company’s common stock equal to 3.0% of the total additional Term Loans funded by the Lenders divided by the lower of (x) the 10-trading day trailing average closing price prior to such Term Loan funding or (y) the closing price on the day prior to such Term Loan funding.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
	Jun. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with United States generally accepted accounting principles, or U.S. GAAP. The condensed consolidated financial statements include the operations of Impel Neuropharma, Inc., and its wholly owned Australian subsidiary. All intercompany balances and transactions have been eliminated upon consolidation. The condensed consolidated balance sheet as of June 30, 2021, the condensed consolidated statements of operations and comprehensive loss, changes in redeemable convertible preferred stock and stockholders’ equity (deficit) and cash flows for the three and six months ended June 30, 2021 and 2020 are unaudited. These unaudited condensed consolidated financial statements have been prepared on the same basis as the annual consolidated financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s consolidated financial position as of June 30, 2021 and its results of operations and cash flows for the three and six months ended June 30, 2021 and 2020. The financial data and the other financial information contained in these notes to the condensed consolidated financial statements related to the three and six month periods are also unaudited. The results of operations for the three months and six months ended June 30, 2021 are not necessarily indicative of the results to be expected for the year ending December 31, 2021 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2020 included herein was derived from the audited financial statements as of that date. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements included in the prospectus dated April 23, 2021 that forms a part of the Company's Registration Statement on Form S-1 (File No. 333-254999), as filed with the SEC pursuant to Rule 424(b)(4) promulgated under the Securities Act of 1933, as amended.
Reclassifications	Reclassifications We have reclassified prior period financial statements to conform to the current period presentation. During the six months ended 2021, we reclassified certain amounts previously recorded as general and administrative expense to research and development expense.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. On an ongoing basis, management evaluates such estimates and assumptions for continued reasonableness. In particular, management makes estimates with respect to the fair values of common stock, redeemable convertible preferred stock warrant liabilities, stock-based compensation expense, convertible debt and income taxes. Appropriate adjustments, if any, to the estimates used are made prospectively based upon such periodic evaluation. Actual results could differ from those estimates.
Segments	Segments The Company’s chief operating decision maker is its Chief Executive Officer. The Chief Executive Officer reviews financial information on an aggregate basis for the purposes of evaluating financial performance and allocating the Company’s resources. Accordingly, the Company has determined that it operates in one segment.
Cash	Cash The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents. At June 30, 2021 and December 31, 2020, cash consisted of cash in bank deposits held at financial institutions.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash. The Company’s cash is deposited with high credit quality financial institutions. At times such deposits may be in excess of the Federal Depository Insurance Corporation insured limits.
Fair Value Measurement	Fair Value Measurement Assets and liabilities recorded at fair value on a recurring basis in the balance sheets are categorized based upon the level of judgment associated with the inputs used to measure their fair values. Fair value is defined as the exchange price that would be received for an asset or an exit price that would be paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1—Observable inputs such as unadjusted, quoted prices in active markets for identical assets or liabilities at the measurement date; Level 2—Inputs (other than quoted prices included in Level 1) are either directly or indirectly observable for the asset or liability. These include quoted prices for similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; Level 3— Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. To the extent that the valuation is based on models or inputs that are less observable or unobservable in the market, the determination of fair value requires more judgment. Accordingly, the degree of judgment exercised by the Company in determining fair value is greatest for instruments categorized in Level 3. A financial instrument’s level within the fair value hierarchy is based on the lowest level of any input that is significant to the fair value measurement. The carrying amounts reflected in the accompanying consolidated balance sheets for cash, other current assets, accounts payable, and accrued liabilities approximate their fair values, due to their short-term nature.
Convertible Notes	Convertible Notes In March 2021, the Company issued convertible promissory notes to various investors for an aggregate amount of $7.5 million. As permitted under Accounting Standards Codification ("ASC") 825, Financial Instruments ("ASC 825"), the Company has elected the fair value option for recognition of the convertible notes. The Company elected the fair value option to allow the Company to eliminate the burden of complying with the requirements for derivative accounting. Under the fair value option, the convertible notes are remeasured at fair value in each reporting period until their conversion in April 2021, with changes in the fair value recognized in the Company’s condensed consolidated statement of operations as other (expense) income, net. Accrued interest on the convertible notes is recorded in other (expense), net.
Deferred Offering Costs	Deferred Offering Costs The Company incurred offering costs consisting of legal, accounting and other fees and costs directly attributable to the Company’s IPO. As of June 30, 2021, $ 2.4 million of deferred offering costs were charged to additional paid-in capital upon the completed of the IPO in April 2021. There were no deferred offering costs as of December 31, 2020
Redeemable Convertible Preferred Stock Warrant Liabilities	Redeemable Convertible Preferred Stock Warrant Liabilities Freestanding warrants to purchase shares of the Company’s redeemable convertible preferred stock are accounted for as liabilities at fair value through the date of exercise, because the shares underlying the warrants contain contingent redemption features outside the control of the Company. Warrants classified as liabilities are recorded on the Company’s condensed consolidated balance sheets at their fair value on the date of issuance and remeasured to fair value each subsequent reporting period, with the changes in fair value recognized as a component of other (expense) income, net in the accompanying condensed consolidated statements of operations. The Company adjusted the liability for the final change in the fair value of these warrants immediately preceding their automatic exercise in connection with the IPO. Upon exercise, the corresponding liability was reclassified to additional paid-in capital.
Research and Development	Research and Development Research and development costs are expensed as incurred and consist primarily of salaries, benefits and other staff-related costs, including associated stock-based compensation, laboratory supplies, nonclinical and clinical studies and trials and related clinical manufacturing costs, costs related to manufacturing preparation, fees paid to other entities that conduct certain research and development activities on the Company’s behalf. Non-refundable advance payments for goods or services that will be used or rendered for future research and development activities are deferred and capitalized as prepaid expenses until the related goods are delivered or services are performed. Such payments are evaluated for current or long-term classification based on when such services are expected to be received.
Advance Payments for Research and Development Services and Accruals	Advance Payments for Research and Development Services and Accruals As part of the process of preparing its condensed consolidated financial statements, the Company is required to estimate its expenses resulting from its obligation under contracts with vendors and consultants and clinical site agreements in connection with its research and development efforts. The financial terms of these contracts are subject to negotiations which vary contract to contract and may result in payment flows that do not match the periods over which materials or services are provided to the Company under such contracts. The Company’s objective is to reflect the appropriate research and development expenses in its condensed consolidated financial statements by matching those expenses with the period in which services and efforts are expended. The Company accounts for these expenses according to the progress of its research and development efforts. The Company determines advance payments for research and development services and accrual estimates through discussion with applicable personnel and outside service providers as to the progress of clinical trials, or other services completed. The Company adjusts its rate of research and development expense recognition if actual results differ from its estimates. The Company makes estimates of its advance payments and accrued expenses as of each balance sheet date in its condensed consolidated financial statements based on facts and circumstances known at that time. Although the Company does not expect its estimates to be materially different from amounts actually incurred, its understanding of status and timing of services performed relative to the actual status and timing of services performed may vary and may result in the Company reporting amounts that are too high or too low for any particular period. Through June 30, 2021, there had been no material adjustments to the Company’s prior period estimates of advance payments and accruals for research and development expenses. The Company’s research and development advance payments and accruals are dependent upon the timely and accurate reporting of contract research organizations and other third-party vendors.
Stock-Based Compensation	Stock-Based Compensation The Company recognizes stock-based compensation expense for stock options and restricted stock unit awards on a straight-line basis over the requisite service period. The Company’s stock-based compensation costs are based upon the grant date fair value of options estimated using the Black-Scholes-Merton option pricing model. This model utilizes as inputs the estimated fair value of the underlying common stock at the measurement date, the estimated term of the stock options (weighted-average period of time that the options granted are expected to be outstanding), risk-free interest rates, expected dividends, and the expected volatility of the Company’s common stock. The Company has elected to recognize forfeitures of share-based payment awards as they occur. The Company recognizes stock-based compensation expense for stock options granted to non-employees based on the estimated fair value of the award as it is more readily measurable than the fair value of the services received.
Net Loss Per Share Attributable to Common Stockholders	Net Loss Per Share Attributable to Common Stockholders Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding for the period, without consideration of potentially dilutive securities. Diluted net loss per share attributable to common stockholders is the same as basic net loss per share attributable to common stockholders since the effect of potentially dilutive securities is anti-dilutive given the net loss of the Company.
Comprehensive Loss	Comprehensive Loss Comprehensive loss represents the change in the Company’s stockholders’ equity (deficit) from all sources other than investments by or distributions to stockholders. The Company has no items of other comprehensive loss; as such, net loss equals comprehensive loss.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In February 2016, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update, or ASU, No. 2016-02, Leases , or Topic 842, which supersedes the guidance in former ASC 840, Leases . This standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification will determine whether lease expense is recognized based on an effective interest method or on a straight-line basis over the term of the lease. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less may be accounted for similar to existing guidance for operating leases today. In May 2020, the FASB issued ASU No. 2020-05, Revenue from Contracts with Customers (Topic 606) and Leases (Topic 842): Effective Dates for Certain Entities, which deferred the effective dates for non-public entities. Therefore, this standard is effective for annual reporting periods, and interim periods within those years, for public entities beginning after December 15, 2018 and for private entities beginning after December 15, 2021. Originally, a modified retrospective transition approach was required for leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements. In July 2018, the FASB issued guidance to permit an alternative transition method for Topic 842, which allows transition to the new lease standard by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. Entities may elect to apply either approach. There are also a number of optional practical expedients that entities may elect to apply. The Company is currently assessing the impact of this standard on its condensed consolidated financial statements. The Company expects to record a material right-of-use asset and lease liability in connection with adopting this standard on January 1, 2022. Recently Adopted Pronouncements In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity , or ASU 2020-06, which simplifies accounting for convertible instruments by removing major separation models required under current U.S. GAAP. ASU 2020-06 removes certain settlement conditions that are required for equity contracts to qualify for the derivative scope exception and it also simplifies the diluted earnings per share calculation in certain areas. ASU 2020-06 is effective for the Company for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020 and adoption must be as of the beginning of the Company’s annual fiscal year. The Company early adopted this standard on January 1, 2021 and the adoption of the standard did not have a significant impact on its consolidated financial statements.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
	Jun. 30, 2021
Fair Value Disclosures [Abstract]
Summary of Fair Value, Liabilities Measured on Recurring Basis	The following table summarizes the fair value of the Company’s financial liabilities measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands): December 31, 2020 Level 1 Level 2 Level 3 Total Liabilities: Redeemable convertible preferred stock warrant liabilities $ — $ — $ 2,622 $ 2,622 Total financial liabilities $ — $ — $ 2,622 $ 2,622
Summary of Change in Fair Value of Redeemable Convertible Preferred Stock Warrant Liabilities and Convertible notes	The following table summarizes the change in the fair value of the redeemable convertible preferred stock warrant liabilities for the six months ended June 30, 2021 (in thousands): Beginning balance as of December 31, 2020 $ 2,622 Losses from changes in fair value 55 Settlement upon IPO ( 2,677 ) Ending balance as of June 30, 2021 $ — The following table summarizes the change in the fair value of the convertible notes for the six months ended June 30, 2021 (in thousands): Beginning balance as of December 31, 2020 $ — Issuance of convertible notes 7,500 Interest 54 Losses from changes in fair value 839 Conversion upon IPO ( 8,393 ) Ending balance as of June 30, 2021 $ —

Balance Sheet Components (Table

Balance Sheet Components (Tables)	6 Months Ended
	Jun. 30, 2021
Balance Sheet Related Disclosures [Abstract]
Schedule of prepaid expenses and other current assets	Prepaid expenses and other current assets consisted of the following (in thousands): June 30, December 31, Refundable clinical deposits $ 337 $ 672 Tax refund receivable 25 229 Prepaid insurance 3,050 47 Other prepaids and current assets 1,207 129 Total prepaid expenses and other current assets $ 4,619 $ 1,077
Schedule of accrued liabilities	Accrued liabilities consisted of the following (in thousands): June 30, December 31, Accrued professional services $ 1,340 $ 192 Accrued compensation 1,986 2,393 Accrued other liabilities 214 333 Accrued construction in progress 6 255 Total accrued liabilities $ 3,546 $ 3,173

Debt (Tables)

Debt (Tables)	6 Months Ended
	Jun. 30, 2021
Debt Disclosure [Abstract]
Schedule of Term Loan	The term loan consists of the following (in thousands): June 30, December 31, Face value of term loan $ 10,000 $ 10,000 Final payment 450 450 Unamortized debt discount associated with final payment, ( 1,593 ) ( 2,039 ) Total debt, net $ 8,857 $ 8,411 Less: short-term debt — 417 Long-term debt $ 8,857 $ 7,994

Redeemable Convertible Prefer_3

Redeemable Convertible Preferred Stock Warrant Liabilities (Tables)	6 Months Ended
	Jun. 30, 2021
Warrants And Rights Note Disclosure [Abstract]
Schedule of Outstanding Redeemable Convertible Preferred Stock Warrant Liabilities	The key terms of the redeemable convertible preferred stock warrant liabilities as of December 31, 2020 are summarized in the following table: Number of shares as of Exercisable into: June 30, December 31, Exercise Expiration Series A-2 redeemable convertible preferred stock — 862,471 $ 0.4996 September 30, 2021 Series C-1 redeemable convertible preferred stock — 1,124,877 0.5289 November 16, 2021 Series D redeemable convertible preferred stock — 1,762,810 0.7091 October 31, 2021 Total — 3,750,158

Redeemable Convertible Prefer_4

Redeemable Convertible Preferred Stock (Tables)	6 Months Ended
	Jun. 30, 2021
Summary of Redeemable Convertible Preferred Stock	Redeemable convertible preferred stock consisted of the following (in thousands, except share amounts) as of December 31, 2020: Redeemable Convertible Shares Authorized Shares Issued and Carrying Value at Aggregate Series A-1 746,426 746,426 $ 238 $ 305 Series A-2 9,869,218 8,805,587 4,147 4,399 Series B 3,968,775 3,968,775 3,980 4,421 Series C-1 43,278,699 42,153,822 20,975 22,297 Series C-2 26,537,826 26,537,826 15,390 15,000 Series C-3 24,605,790 24,605,790 14,973 15,000 Series D 95,191,755 95,191,755 67,336 67,500 Total 204,198,489 202,009,981 $ 127,039 $ 128,922

Common Stock (Tables)

Common Stock (Tables)	6 Months Ended
	Jun. 30, 2021
Equity [Abstract]
Schedule of Reserved Shares of Common Stock for Issuance, on an as-Converted Basis	The Company has reserved the following shares of common stock for issuance, on an as-converted basis, as follows: June 30, December 31, Stock incentive plans 5,219,804 2,786,345 Redeemable convertible preferred stock — 12,605,800 Convertible notes — — Redeemable convertible preferred stock warrants — 229,034 Total 5,219,804 15,621,179

Stock Incentive Plan (Tables)

Stock Incentive Plan (Tables)	6 Months Ended
	Jun. 30, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of the Company's Stock Option Activity under its Stock Option Plans	A summary of the Company’s stock option activity under its stock option plans was as follows (in thousands, except share and per share data and years): Options Outstanding Shares Number of Weighted Remaining Aggregate Balance — December 31, 2020 344,456 2,441,889 $ 5.17 8.02 $ 14,844 Authorized 2,205,000 — Granted ( 408,464 ) 408,464 $ 12.39 Exercised — ( 47,539 ) $ 4.61 Cancelled 32,029 ( 32,059 ) $ 4.86 Balance — June 30, 2021 2,173,021 2,770,755 $ 6.25 7.87 $ 8,600 Exercisable — June 30, 2021 — 1,316,271 $ 4.00 6.88 $ 6,388
Schedule of Stock-Based Compensation Expense Recognized	Stock-based compensation expense recognized was as follows (in thousands): Three Months Ended Six Months Ended 2021 2020 2021 2020 Research and development $ 437 $ 2,360 $ 811 $ 2,539 General and administrative 119 125 238 244 Total stock-based compensation expense $ 556 $ 2,485 $ 1,049 $ 2,783
Schedule of Fair Value of Stock Option Awards Granted to Employees	The fair value of stock option awards granted to employees was estimated at the date of grant using a Black-Scholes-Merton option pricing model with the following assumptions: Three Months Ended Six Months Ended 2021 2020 2021 2020 Expected term (in years) 6.1 6.1 6.1 6.1 Expected volatility 59.2 - 85.5 % 56.4 - 57.6 % 59.2 - 85.5 % 56.4 - 57.6 % Risk-free interest rate 0.79 - 0.86 % 0.41 - 0.50 % 0.42 - 0.92 % 0.41 - 1.55 % Expected dividends — — — —

Net Loss Per Share Attributab_2

Net Loss Per Share Attributable to Common Stockholders (Tables)	6 Months Ended
	Jun. 30, 2021
Earnings Per Share [Abstract]
Schedule of Outstanding Shares of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders	The following outstanding shares of potentially dilutive securities were excluded from the computation of the diluted net loss per share attributable to common stockholders for the periods presented because their effect would have been anti-dilutive: Six Months Ended 2021 2020 Redeemable convertible preferred stock on an as-converted basis — 12,541,308 Redeemable convertible preferred stock warrants on an as-converted basis — 160,349 Convertible notes on an as-converted basis — — Stock options to purchase common stock 2,770,785 3,033,481 Total 2,770,785 15,735,138

Organization and Description _2

Organization and Description of Business - Additional Information (Details) - USD ($)	Apr. 23, 2021	Apr. 30, 2021	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Date of incorporation					Jul. 24, 2008
Proceeds from initial public offering, net of issuance costs					$ 71,997,000	$ 0
Proceeds from issuance of common stock, net of underwriters discount and commissions					$ 71,997,000	$ 0
Reverse stock split, description					effect a reverse split of shares of the Company’s common stock on an one-for-16.37332 basis, which was effected on April 16, 2021 (the “Reverse Stock Split”). The number of authorized shares and the par values of the common stock and redeemable convertible preferred stock were not adjusted as a result of the Reverse Stock Split. In connection with the Reverse Stock Split, the conversion ratio for the Company’s outstanding redeemable convertible preferred stock was proportionately adjusted such that the common stock issuable upon conversion of such preferred stock was decreased in proportion to the Reverse Stock Split.
Proceeds from issuance or sale of equity, debt and warrants					$ 214,500,000
Cash				$ 60,948,000	60,948,000		$ 7,095,000
Common Stock
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering, Shares	12,605,800
Common shares exercised	61,515
Common Stock | Avenue Venture Opportunities Fund L P
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of warrant, shares converted	107,663
Warrant to Purchase Common Stock [Member] | Avenue Venture Opportunities Fund L P
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of warrant, shares converted	1,987,348
Convertible Notes [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Conversion of redeemable convertible preferred stock to common stock upon initial public offering, Shares			559,585
Conversion of convertible notes, amout converted			$ 7,500,000
Discount of initial public offering price			10.00%
Initial public offering
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Proceeds from initial public offering, net of underwriters' discounts and commissions, Shares	5,333,334
Shares price per share	$ 15
Proceeds from initial public offering, net of issuance costs	$ 72,000,000	$ 72,000,000
Payments of stock issuance offering costs	2,400
Payment of underwriting discounts, commissions	5,600,000
Proceeds from issuance of common stock, net of underwriters discount and commissions	$ 72,000,000	$ 72,000,000
Conversion of convertible notes, amout converted				127,168,000
Remaining borrowing capacity				$ 50,000,000	$ 50,000,000

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Additional Information (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)Segment	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Number of operating segments | Segment	1
Face value of term loan	$ 10,000		$ 10,000
Deferred offering costs	$ 2,400		$ 0
Convertible Promissory Notes
Debt Instrument [Line Items]
Face value of term loan		$ 7,500

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Fair Value, Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Liabilities:
Total financial liabilities		$ 2,622
Redeemable Convertible Preferred Stock Warrant Liability [Member]
Liabilities:
Total financial liabilities	$ 0	2,622
Convertible Notes [Member]
Liabilities:
Total financial liabilities	$ 0	0
Level 1 [Member]
Liabilities:
Total financial liabilities		0
Level 1 [Member] | Redeemable Convertible Preferred Stock Warrant Liability [Member]
Liabilities:
Total financial liabilities		0
Level 2 [Member]
Liabilities:
Total financial liabilities		0
Level 2 [Member] | Redeemable Convertible Preferred Stock Warrant Liability [Member]
Liabilities:
Total financial liabilities		0
Level 3 [Member]
Liabilities:
Total financial liabilities		2,622
Level 3 [Member] | Redeemable Convertible Preferred Stock Warrant Liability [Member]
Liabilities:
Total financial liabilities		$ 2,622

Fair Value Measurements - Sum_2

Fair Value Measurements - Summary of Change in Fair Value of Redeemable Convertible Preferred Stock Warrant Liabilities and Convertible notes (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2021USD ($)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning balance	$ 2,622
Redeemable Convertible Preferred Stock Warrant Liability [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning balance	2,622
Losses from changes in fair value	55
Liabilities fair value settlement upon IPO	(2,677)
Ending balance	0
Convertible Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Beginning balance	0
Losses from changes in fair value	839
Issuance of convertible notes	7,500
Liabilities fair value conversion upon IPO	(8,393)
Liabilities fair value interest	54
Ending balance	$ 0

Balance Sheet Components - Sche

Balance Sheet Components - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Refundable clinical deposits	$ 337	$ 672
Tax refund receivable	25	229
Prepaid insurance	3,050	47
Other prepaids and current assets	1,207	129
Total prepaid expenses and other current assets	$ 4,619	$ 1,077

Balance Sheet Components - Sc_2

Balance Sheet Components - Schedule of Accrued Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Balance Sheet Related Disclosures [Abstract]
Accrued professional services	$ 1,340	$ 192
Accrued compensation	1,986	2,393
Accrued other liabilities	214	333
Accrued construction in progress	6	255
Total accrued liabilities	$ 3,546	$ 3,173

Commitments and Contingencies (

Commitments and Contingencies (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Jun. 30, 2020USD ($)	Sep. 30, 2017ft²
Commitments And Contingencies Disclosure [Abstract]
Non cancelable operating lease area | ft²					11,256
Remaining future minimum lease payments	$ 800,000		$ 800,000
Percentage increase in rent payable monthly			3.00%
Operating lease expiration date			Aug. 31, 2022
Rent expenses	$ 175,000	$ 188,000	$ 349,000	$ 344,000

Debt - Additional Information (

Debt - Additional Information (Details) - USD ($)	Nov. 05, 2020	Mar. 31, 2021	Jun. 30, 2021	Jun. 30, 2021	Jul. 02, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Net proceeds from issuance of term loan				$ 1,500,000
Financing cost			$ 299,000	299,000
Interest expense			509,000	999,000
Face value of term loan			10,000,000	10,000,000		$ 10,000,000
Carrying amount of term loan			450,000	450,000		$ 450,000
Convertible Notes On Conversion Basis [Member]
Debt Instrument [Line Items]
Conversion of convertible notes to common shares at IPO		559,585
I P O [Member]
Debt Instrument [Line Items]
Remaining borrowing capacity			$ 50,000,000	$ 50,000,000
Carrying value of convertible notes		$ 8,400,000
Term Loan [Member]
Debt Instrument [Line Items]
Term of loan	36 months
Current borrowing capacity	$ 10,000,000				$ 20,000,000
Remaining borrowing capacity	$ 10,000,000				$ 10,800,000
Debt instrument interest rate stated percentage	11.00%
Final principal payment	$ 450,000
Term Loan [Member] | Series D Preferred Stock [Member]
Debt Instrument [Line Items]
Granted warrants for the purchase of shares	1,762,810
Term Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Maximum credit commitment	$ 20,000,000
Term Loan [Member] | Minimum [Member] | I P O [Member]
Debt Instrument [Line Items]
Gross proceeds	$ 75,000,000
Convertible Promissory Notes [Member]
Debt Instrument [Line Items]
Debt instrument interest rate stated percentage		5.00%
Face value of term loan		$ 7,500,000
Debt instrument, maturity date		Dec. 31, 2021

Debt - Schedule of Term Loan (D

Debt - Schedule of Term Loan (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Face value of term loan	$ 10,000	$ 10,000
Final payment	450	450
Unamortized debt discount associated with final payment, issuance date warrant fair value, and financing costs	(1,593)	(2,039)
Total debt, net	8,857	8,411
Less: short-term debt	0	417
Long-term debt	$ 8,857	$ 7,994

Redeemable Convertible Prefer_5

Redeemable Convertible Preferred Stock Warrant Liabilities - Schedule of Outstanding Redeemable Convertible Preferred Stock Warrant Liabilities (Details) - $ / shares	Jun. 30, 2021	Dec. 31, 2020
Class Of Warrant Or Right [Line Items]
Redeemable convertible preferred stock warrant liabilities, Number of shares outstanding	0	3,750,158
Series A-2 Redeemable Convertible Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Redeemable convertible preferred stock warrant liabilities, Number of shares outstanding	0	862,471
Redeemable convertible preferred stock warrant liabilities, Exercise Price	$ 0.4996
Redeemable convertible preferred stock warrant liabilities, Expiration	Sep. 30, 2021
Series C-1 Redeemable Convertible Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Redeemable convertible preferred stock warrant liabilities, Number of shares outstanding	0	1,124,877
Redeemable convertible preferred stock warrant liabilities, Exercise Price	$ 0.5289
Redeemable convertible preferred stock warrant liabilities, Expiration	Nov. 16, 2021
Series D Redeemable Convertible Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Redeemable convertible preferred stock warrant liabilities, Number of shares outstanding	0	1,762,810
Redeemable convertible preferred stock warrant liabilities, Exercise Price	$ 0.7091
Redeemable convertible preferred stock warrant liabilities, Expiration	Oct. 31, 2021

Redeemable Convertible Prefer_6

Redeemable Convertible Preferred Stock Warrant Liabilities - Additional Information (Details) - shares	1 Months Ended	6 Months Ended
	Apr. 30, 2021	Jun. 30, 2021
Class Of Warrant Or Right [Line Items]
Expected volatility rate, minimum		46.40%
Expected volatility rate, maximum		103.00%
Risk-free interest rate, minimum		0.04%
Risk-free interest rate, maximum		0.24%
Series A-2 Redeemable Convertible Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Warrant exercised	61,515
Series D Preferred Stock [Member]
Class Of Warrant Or Right [Line Items]
Warrant exercised	107,663

Redeemable Convertible Prefer_7

Redeemable Convertible Preferred Stock - Summary of Redeemable Convertible Preferred Stock (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized	204,198,489	204,198,489
Shares Issued and Outstanding		202,009,981
Carrying Value		$ 127,039
Redeemable convertible preferred stock, liquidation preference value		$ 128,922
Series A-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		746,426
Shares Issued and Outstanding		746,426
Carrying Value		$ 238
Redeemable convertible preferred stock, liquidation preference value		$ 305
Series A-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		9,869,218
Shares Issued and Outstanding		8,805,587
Carrying Value		$ 4,147
Redeemable convertible preferred stock, liquidation preference value		$ 4,399
Series B Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		3,968,775
Shares Issued and Outstanding		3,968,775
Carrying Value		$ 3,980
Redeemable convertible preferred stock, liquidation preference value		$ 4,421
Series C-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		43,278,699
Shares Issued and Outstanding		42,153,822
Carrying Value		$ 20,975
Redeemable convertible preferred stock, liquidation preference value		$ 22,297
Series C-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		26,537,826
Shares Issued and Outstanding		26,537,826
Carrying Value		$ 15,390
Redeemable convertible preferred stock, liquidation preference value		$ 15,000
Series C-3 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		24,605,790
Shares Issued and Outstanding		24,605,790
Carrying Value		$ 14,973
Redeemable convertible preferred stock, liquidation preference value		$ 15,000
Series D Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Redeemable convertible preferred stock, shares authorized		95,191,755
Shares Issued and Outstanding		95,191,755
Carrying Value		$ 67,336
Redeemable convertible preferred stock, liquidation preference value		$ 67,500

Redeemable Convertible Prefer_8

Redeemable Convertible Preferred Stock - Additional Information (Details) - USD ($)	Apr. 30, 2021	Jun. 30, 2021	Jun. 30, 2020
Series A-1 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity, accretion to redemption value		$ 0	$ 0
Series A-2 Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity, accretion to redemption value		0	0
Redeemable Convertible Preferred Stock [Member]
Temporary Equity [Line Items]
Temporary equity, accretion to redemption value		0	0
Temporary equity, accretion of dividends		$ 129,000	$ 256,000,000
Number of common stock shares issued upon conversion	12,605,800
Carrying value reclassified to equity	$ 127,200,000

Common Stock - Additional Infor

Common Stock - Additional Information (Details) - Common Stock [Member]	6 Months Ended
	Jun. 30, 2021USD ($)
Common stock, voting rights	Each share of common stock has the right to one vote.
Cash dividends declared	$ 0

Common Stock - Schedule of Rese

Common Stock - Schedule of Reserved Shares of Common Stock for Issuance, on an as-Converted Basis (Details) - shares	Jun. 30, 2021	Dec. 31, 2020
Common stock, reserved for future issuance	5,219,804	15,621,179
Stock Incentive Plans [Member]
Common stock, reserved for future issuance	5,219,804	2,786,345
Redeemable Convertible Preferred Stock [Member]
Common stock, reserved for future issuance	0	12,605,800
Convertible Notes [Member]
Common stock, reserved for future issuance	0	0
Redeemable Convertible Preferred Stock Warrant [Member]
Common stock, reserved for future issuance	0	229,034

Stock Incentive Plan - Addition

Stock Incentive Plan - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		6 Months Ended
	May 31, 2020	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding		2,770,755		2,770,755		2,441,889
Common stock, reserved for future issuance		5,219,804		5,219,804		15,621,179
Number of shares available for grant		2,173,021		2,173,021		344,456
Increase in number of shares available for future grant	596,414
Stock options, grants in period				408,464
Stock options, grants in period, weighted-average exercise price				$ 12.39
Accelerated cost					$ 2,100
Stock options, exercises in period, total intrinsic value				$ 202,000	26,000
Stock options, vested in period, fair value				1,300	900
Stock options. grants in period, grant date fair value				$ 3,800	$ 2,900
Stock options, grants in period, weighted-average grant date fair value				$ 7.22	$ 4.42
Unvested stock options, cost not yet recognized, amount		$ 5,000		$ 5,000
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested award, cost not yet recognized, period for recognition				2 years 9 months 18 days
Expected dividend yield		0.00%	0.00%	0.00%	0.00%
Stock Options [Member] | Chief Executive Officer [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	48 months
Stock options, grants in period	715,358
Stock options, grants in period, weighted-average exercise price	$ 7.86
2008 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Plan term				10 years
Stock options outstanding		604,267		604,267		634,788
2018 Stock Incentive Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding		2,034,734		2,034,734		1,807,101
Common stock, reserved for future issuance		753,645		753,645
2021 Equity Incentive Plan Policies [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options outstanding		131,621		131,621
Common stock, reserved for future issuance		2,205,000		2,205,000
Number of shares reserved for issuance.				2,272,613
Percentage of total number of outstanding shares of common stock				5.00%
2021 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, reserved for future issuance		276,000		276,000

Stock Incentive Plan - Summary

Stock Incentive Plan - Summary of the Company's Stock Option Activity under its Stock Option Plans (Details) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Beginning Balance	344,456
Shares Available for Grant, Authorized	2,205,000
Shares Available for Grant, Granted	(408,464)
Shares Available for Grant, Cancelled	32,029
Shares Available for Grant, Ending Balance	2,173,021		344,456
Number of Options, Beginning Balance	2,441,889
Number of Options, Granted	408,464
Issuance of common stock upon the exercise of stock options, Shares	47,539
Number of Options, Cancelled	32,059
Number of Options, Ending Balance	2,770,755		2,441,889
Number of Options, Exercisable	1,316,271
Weighted-Average Exercise Price, Beginning Balance	$ 5.17
Weighted-Average Exercise Price, Granted	12.39
Weighted-Average Exercise Price, Exercised	4.61
Weighted-Average Exercise Price, Cancelled	4.86
Weighted-Average Exercise Price, Ending Balance	6.25		$ 5.17
Weighted-Average Exercise Price, Exercisable	$ 4
Remaining Contractual Term (Years), Balance	7 years 10 months 13 days		8 years 7 days
Remaining Contractual Term (Years), Exercisable	6 years 10 months 17 days
Aggregate Intrinsic Value, Beginning Balance	$ 14,844
Aggregate Intrinsic Value, Exercised	202,000	$ 26,000
Aggregate Intrinsic Value, Ending Balance	8,600		$ 14,844
Aggregate Intrinsic Value, Exercisable	$ 6,388

Stock Incentive Plan - Schedule

Stock Incentive Plan - Schedule of Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 556	$ 2,485	$ 1,049	$ 2,783
Research and Development [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	437	2,360	811	2,539
General and Administrative [Member]
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 119	$ 125	$ 238	$ 244

Stock Incentive Plan - Schedu_2

Stock Incentive Plan - Schedule of Fair Value of Stock Option Awards Granted to Employees (Details) - Stock Options [Member]	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]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Expected dividends	0.00%	0.00%	0.00%	0.00%
Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	59.20%	56.40%	59.20%	56.40%
Risk-free interest rate	0.79%	0.41%	0.42%	0.41%
Maximum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	85.50%	57.60%	85.50%	57.60%
Risk-free interest rate	0.86%	0.50%	0.92%	1.55%

Defined Contribution Plan - Add

Defined Contribution Plan - Additional Information (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Compensation And Retirement Disclosure [Abstract]
Maximum Employee's Contribution, Percent			4.00%
Expense, Defined Contribution Plan	$ 70,000	$ 62,000	$ 181,000	$ 157,000

Net Loss Per Share Attributab_3

Net Loss Per Share Attributable to Common Stockholders - Schedule of Outstanding Shares of Potentially Dilutive Securities Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,770,785	15,735,138
Redeemable Convertible Preferred Stock on an as-Converted Basis [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0	12,541,308
Redeemable Convertible Preferred Stock Warrants on an as Converted Basis [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0	160,349
Convertible Notes On Conversion Basis [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	0	0
Stock Options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,770,785	3,033,481

Subsequent Event (Additional In

Subsequent Event (Additional Information) (Details) - USD ($)	Nov. 05, 2020	Jun. 30, 2021	Jul. 02, 2021	Dec. 31, 2020
Subsequent Event [Line Items]
Final Payment Percentage of Principal Amount Term Loan		6.50%
Term Loan Final Payment Description		The Company will be required to make a final payment of 6.5% of the original principal amount of the Term Loans drawn, payable on the earlier of (i) the Maturity Date, (ii) the acceleration of any Term Loans, or (iii) the prepayment of the Term Loans (the “Final Payment”). The Company may prepay all, but not less than all, of the Term Loans upon 30 days’ advance written notice to Oxford, provided that the Company will be obligated to pay a prepayment fee equal to (i) 3.0% of the principal amount of the applicable Term Loan prepaid on or before the first anniversary of the applicable funding date, (ii) 2.0% of the principal amount of the applicable Term Loan prepaid between the first and second anniversary of the applicable funding date, and (iii) 1.0% of the principal amount of the applicable Term Loan prepaid thereafter, and prior to the Maturity Date (each, a “Prepayment Fee”).
Common Stock Issued As Warrant Exercisable		19,470,914		755,478
Term Loan [Member]
Subsequent Event [Line Items]
Current borrowing capacity	$ 10,000,000		$ 20,000,000
Final principal payment	$ 450,000
Term of loan	36 months
Term A Loan [Member] | Warrant [Member]
Subsequent Event [Line Items]
Common Stock Issued As Warrant Exercisable		71,522
Warrant Exercise Price Per Share		$ 8.389
Warrant Expiration Date		Jul. 2, 2031
Term C Loan [Member]
Subsequent Event [Line Items]
Net revenue		$ 15,000,000
Long-term Debt, Maturity Date		Jul. 1, 2026
Term of loan		35 months
Subsequent Event [Member] | Term B Loan [Member]
Subsequent Event [Line Items]
Line Of Credit Facility Additional Borrowing Loan Amount			10,000,000
Subsequent Event [Member] | Term C Loan [Member]
Subsequent Event [Line Items]
Line Of Credit Facility Additional Borrowing Loan Amount			$ 20,000,000