0000950170-22-009686 | 10-Q | XBRL Viewer

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Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2022	May 06, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	KZR
Entity Registrant Name	Kezar Life Sciences, Inc.
Entity Central Index Key	0001645666
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Emerging Growth Company	true
Entity Small Business	true
Entity Ex Transition Period	true
Entity Common Stock, Shares Outstanding		60,415,586
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38542
Entity Tax Identification Number	47-3366145
Entity Address, Address Line One	4000 Shoreline Court
Entity Address, Address Line Two	Suite 300
Entity Address, City or Town	South San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94080
City Area Code	650
Local Phone Number	822-5600
Document Quarterly Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, $0.001 par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	DE

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Current assets:
Cash and cash equivalents	$ 38,908	$ 62,882
Marketable securities	203,701	145,473
Prepaid expenses	2,331	2,570
Other current assets	1,056	729
Total current assets	245,996	211,654
Property and equipment, net	3,041	3,283
Operating lease right-of-use asset	2,547	2,714
Other assets	282	282
Total assets	251,866	217,933
Current liabilities:
Accounts payable	1,359	2,028
Accrued and other current liabilities	4,378	4,985
Operating lease liabilities, current	1,241	1,199
Total current liabilities	6,978	8,212
Operating lease liabilities, noncurrent	2,898	3,223
Debt, noncurrent	9,675	9,622
Total liabilities	19,551	21,057
Stockholders' equity:
Common stock, $0.001 par value, 125,000,000 shares authorized as of March 31, 2022 (unaudited) and December 31, 2021; 59,564,659 and 56,259,747 shares issued and outstanding as of March 31, 2022 (unaudited) and December 31, 2021, respectively	60	56
Preferred stock, $0.001 par value, 10,000,000 shares authorized, zero shares issued and outstanding as of March 31, 2022 (unaudited) and December 31, 2021	0	0
Additional paid-in capital	429,715	377,765
Accumulated other comprehensive loss	(782)	(291)
Accumulated deficit	(196,678)	(180,654)
Total stockholders' equity	232,315	196,876
Total liabilities and stockholders' equity	$ 251,866	$ 217,933

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	59,564,659	56,259,747
Common stock, shares outstanding	59,564,659	56,259,747
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 10,944	$ 9,286
General and administrative	4,934	3,762
Total operating expenses	15,878	13,048
Operating Income (Loss), Total	(15,878)	(13,048)
Interest income	108	54
Interest Expense	(254)
Net loss	$ (16,024)	$ (12,994)
Net loss per common share, basic and diluted	$ (0.26)	$ (0.25)
Weighted-average shares used to compute net loss per common share, basic and diluted	60,630,389	51,058,039

Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (16,024)	$ (12,994)
Other comprehensive (loss) income
Foreign currency translation adjustments	25	(11)
Unrealized (loss) gain on marketable securities	(516)	8
Total other comprehensive (loss) income, net of tax	(491)	(3)
Comprehensive loss	$ (16,515)	$ (12,997)

- Definition

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

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+ Details

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	ATM Agreement	Common Stock	Common Stock ATM Agreement	Additional Paid-in Capital	Additional Paid-in Capital ATM Agreement	Accumulated Other Comprehensive Income/(Loss)	Accumulated Deficit
Balance at Dec. 31, 2020	$ 140,978		$ 46		$ 267,093		$ (137)	$ (126,024)
Balance, shares at Dec. 31, 2020			46,359,743
Issuance of common stock net of offering costs		$ 10,673		$ 2		$ 10,671
Issuance of common stock net of offering costs, shares				1,705,800
Issuance of common stock under employee stock incentive plans	48				48
Issuance of common stock under employee stock incentive plans, shares			14,325
Vesting related to shares of common stock issued pursuant to early exercises	7				7
Stock-based compensation expense	1,928				1,928
Other comprehensive (loss) income	(3)						(3)
Net loss	(12,994)							(12,994)
Balance at Mar. 31, 2021	140,637		$ 48		279,747		(140)	(139,018)
Balance, shares at Mar. 31, 2021			48,079,868
Balance at Dec. 31, 2021	196,876		$ 56		377,765		(291)	(180,654)
Balance, shares at Dec. 31, 2021			56,259,747
Issuance of common stock net of offering costs		$ 48,642		$ 4		$ 48,638
Issuance of common stock net of offering costs, shares				3,245,738
Issuance of common stock under employee stock incentive plans	208				208
Issuance of common stock under employee stock incentive plans, shares			59,174
Stock-based compensation expense	3,104				3,104
Other comprehensive (loss) income	(491)						(491)
Net loss	(16,024)							(16,024)
Balance at Mar. 31, 2022	$ 232,315		$ 60		$ 429,715		$ (782)	$ (196,678)
Balance, shares at Mar. 31, 2022			59,564,659

Condensed Consolidated Statements of Stockholders' Equity (Parenthetical) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
ATM Agreement
Issuance of common stock under the ATM Agreement, net of offering costs	$ 1,504	$ 330

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash flows from operating activities:
Net loss	$ (16,024)	$ (12,994)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	417	372
Stock-based compensation	3,104	1,928
Amortization of premiums and discounts on marketable securities	339	514
Amortization of debt discount and issuance costs and other non-cash interest	53	0
Changes in operating assets and liabilities
Prepaid expenses, other current assets and other long-term assets	(86)	980
Accounts payable, accrued and other current liabilities	(834)	1,088
Operating lease liabilities	(283)	(245)
Net cash used in operating activities	(13,314)	(8,357)
Cash flows from investing activities:
Purchases of property and equipment	(450)	0
Purchases of marketable securities	(74,522)	(26,187)
Maturities of marketable securities	15,439	25,500
Net cash provided by (used in) investing activities	(59,533)	(687)
Cash flows from financing activities:
Proceeds from issuance of common stock and warrants, net of issuance costs	48,642	10,673
Proceeds from issuance of common stock under employee stock incentive plans	206	62
Net cash provided by financing activities	48,848	10,735
Effect of exchange rate changes on cash and cash equivalents	25	(11)
Net increase (decrease) in cash and cash equivalents	(23,974)	1,680
Cash and cash equivalents at the beginning of period	62,882	21,228
Cash and cash equivalents at the end of period	38,908	22,908
Supplemental disclosures of noncash investing and financing information:
Reclassification of employee stock liability to equity upon vesting	0	7
Unpaid offering costs in accrued liabilities	0	25
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	$ 201	$ 0

Organization and Description of the Business

3 Months Ended

Mar. 31, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization and Description of the Business

1. Organization and Description of the Business

Description of Business

Kezar Life Sciences, Inc. (the “Company,” “we,” “us,” or “our”) was incorporated in the state of Delaware in February 2015 and commenced operations in June 2015. The Company is a clinical-stage biotechnology company discovering and developing breakthrough treatments in immune-mediated and oncologic disorders. The Company’s principal operations are in South San Francisco, California, and it operates in one segment.

Liquidity

Since commencing operations in mid-2015, substantially all of the Company’s efforts have been focused on research, development, and the advancement of the Company’s product candidates, KZR-616 (zetomipzomib) and KZR-261. The Company’s ultimate success depends on the outcome of these ongoing research and development activities. The Company has not yet generated product sales and as a result has experienced operating losses since inception and had an accumulated deficit of $196.7 million as of March 31, 2022. The Company expects to incur additional losses in the future to conduct research and development and will need to raise additional capital to fully implement management’s business plan. The Company intends to raise such capital through the issuance of additional equity, and potentially through borrowings, strategic alliances with partner companies and other licensing transactions. However, if such financing is not available at adequate levels, the Company may need to reevaluate its operating plans. Management believes that its existing cash, cash equivalents and marketable securities will be sufficient to fund the Company’s cash requirements for at least 12 months following the issuance of these financial statements.

In December 2021, the Company entered into a Sales Agreement (the “ATM Agreement”) with Cowen and Company, LLC (“Cowen”), pursuant to which the Company can offer and sell, from time to time at its sole discretion through Cowen, as its sales agent, shares of its common stock having an aggregate offering price of up to $200.0 million. Any shares of its common stock sold will be issued pursuant to the Company’s shelf registration statement on Form S-3ASR (File No. 333-261774). The Company will pay Cowen a commission equal to 3.0% of the gross sales proceeds of any shares of its common stock sold through Cowen under the ATM Agreement and also has provided Cowen with indemnification and contribution rights.

During the three months ended March 31, 2022, the Company sold an aggregate of 3,245,738 shares of its common stock at a weighted average purchase price of $15.45 per share pursuant to the ATM Agreement for net proceeds of approximately $48.6 million. Subsequent to March 31, 2022, the Company sold an additional 820,000 shares of its common stock pursuant to the ATM Agreement for net proceeds of approximately $13.4 million at a weighted average purchase price of $16.82 per share.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Significant Accounting Policies

The Company’s significant accounting policies are disclosed in the audited consolidated financial statements for the year ended December 31, 2021 and the notes thereto, which are included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2021, filed with the U.S. Securities and Exchange Commission (“SEC”) on March 17, 2022 (the “Annual Report”), and there have been no material changes during the three months ended March 31, 2022.

Basis of Presentation and Consolidation

The condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and include the Company’s accounts and those of its wholly owned Australian subsidiary, Kezar Life Sciences Australia Pty Ltd., which is a proprietary company limited by shares. All intercompany balances and transactions have been eliminated upon consolidation.

The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited consolidated financial statements at that date but does not include all information and footnotes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements included in the Annual Report.

Unaudited Condensed Consolidated Financial Statements

The accompanying financial information as of March 31, 2022 is unaudited. The interim condensed consolidated financial statements included in this report reflect all adjustments (consisting only of normal recurring adjustments) that our management considers necessary for the fair statement of the results of operations for the interim periods covered and of our financial condition at the date of the interim balance sheet. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The results for interim periods are not necessarily indicative of the results for the entire year or any other interim period. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our Annual Report.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include the stock-based compensation, and accrued research and development costs. Management bases its estimates on historical experience and on various other market-specific relevant assumptions that management believes to be reasonable under the circumstances. Actual results may differ from those estimates.

The Company anticipates that the ongoing COVID-19 pandemic, recent geopolitical events and supply-chain concerns could have an impact on our clinical development timelines. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s consolidated financial statements.

Significant Risks and Uncertainties

The Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its business. The extent to which the COVID-19 pandemic impacts the Company’s business, preclinical and clinical development and regulatory efforts, corporate development objectives and the value of and market for its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing, safety measures and business closure requirements in the United States, Europe, China and other countries where we conduct clinical trials and/or manufacture our product candidates. The global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the pandemic, geopolitical events and global supply chains could have a material adverse effect on the Company’s business, financial condition, results of operations and growth prospects.

In addition, the Company is subject to other challenges and risks specific to its business and its ability to execute on its strategy, as well as risks and uncertainties common to companies in the biotechnology industry with development operations, including, without limitation, risks and uncertainties associated with: obtaining regulatory feedback regarding the Company’s product candidates; delays or problems in the supply of its product candidates; loss of single source suppliers or their failure to comply with manufacturing regulations; identifying, acquiring or in-licensing additional technologies or product candidates; clinical development and the inherent uncertainty of clinical success; the challenges of protecting and enhancing its intellectual property rights; and complying with applicable regulatory requirements.

Recent Accounting Pronouncements

The Company continues to monitor new accounting pronouncements issued by the Financial Accounting Standards Board and does not believe any accounting pronouncements issued through the date of this report will have a material impact on the Company’s condensed consolidated financial statements.

Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, marketable securities, other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the condensed consolidated 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. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

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

Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities.

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.

Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability.

The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the financial statements. The Company determines the fair value of Level 1 assets using quoted prices in active markets for identical assets. The Company reviews trading activity and pricing for Level 2 investments as of each measurement date. Level 2 inputs, which are obtained from various third-party data providers, represent quoted prices for similar assets in active markets and were derived from observable market data, or, if not directly observable, were derived from or corroborated by other observable market data.

In certain cases, where there is limited activity or less transparency around inputs to valuation, securities are classified as Level 3 within the valuation hierarchy. The Company did not have any assets or liabilities measured using Level 3 inputs as of March 31, 2022 or December 31, 2021.

The following table summarizes the Company’s financial assets measured at fair value on a recurring basis and classified under the appropriate level of the fair value hierarchy as described above (in thousands):


	March 31, 2022
	Total		Level 1		Level 2		Level 3
Financial Assets:
U.S. Treasury money market funds	$	22,334	$	22,334	$	—	$	—
U.S. Treasury securities		141,731		141,731		—		—
Commercial paper		74,744		—		74,744		—
U.S. agency bonds		1,197		—		1,197		—
Total	$	240,006	$	164,065	$	75,941	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Financial Assets:
U.S. Treasury money market funds	$	60,375	$	60,375	$	—	$	—
U.S. Treasury securities		82,106		82,106		—		—
Commercial paper		46,687		—		46,687		—
Corporate debt securities		15,481		—		15,481		—
U.S. agency bonds		1,199		—		1,199		—
Total	$	205,848	$	142,481	$	63,367	$	—

- Definition

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

+ References + Details

Available-for-Sale Securities

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

Available-for-Sale Securities

4. Available-for-Sale Securities

The following table is a summary of available-for-sale securities recorded in cash and cash equivalents or marketable securities in the Company’s condensed consolidated balance sheets (in thousands):


	March 31, 2022
Financial Assets	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury money market funds	$	22,334	$	—	$	—		$	22,334
U.S. Treasury securities		142,185		—		(454	)		141,731
Commercial paper		74,898		—		(154	)		74,744
U.S. agency bonds		1,200		—		(3	)		1,197
Total	$	240,617	$	—	$	(611	)	$	240,006


	December 31, 2021
Financial Assets	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury money market funds	$	60,375	$	—	$	—		$	60,375
U.S. Treasury securities		82,204		—		(98	)		82,106
Commercial paper		46,678		13		(4	)		46,687
Corporate debt securities		15,486		—		(5	)		15,481
U.S. agency bonds		1,200		—		(1	)		1,199
Total	$	205,943	$	13	$	(108	)	$	205,848

As of March 31, 2022 and December 31, 2021, the Company has not recognized an allowance for credit losses on any securities in an unrealized loss position.

The following table displays additional information regarding gross unrealized losses and fair value by major security type for available-for-sale securities in an unrealized loss position as of March 31, 2022 and December 31, 2021 (in thousands):


	March 31, 2022					December 31, 2021
	Less than 12 consecutive months					Less than 12 consecutive months
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities	$	141,731	$	(454	)	$	82,106	$	(98	)
Commercial paper	$	74,744	$	(154	)		13,734		(4	)
Corporate debt securities		—		—			15,481		(5	)
U.S. agency bonds		1,197		(3	)		1,199		(1	)
Total	$	217,672	$	(611	)	$	112,520	$	(108	)

The Company believes that the individual unrealized losses represent temporary declines primarily resulting from interest rate changes. The Company currently does not intend to sell these securities prior to maturity and does not consider these investments to be other-than-temporarily impaired at March 31, 2022. There were no sales of available-for-sale securities in any of the periods presented.

As of March 31, 2022, the amortized cost and estimated fair value of the Company’s available-for-sale securities by contractual maturity are shown below (in thousands):


	Amortized		Estimated
Available-for-sale securities maturing:	Cost		Fair Value
In one year or less	$	240,617	$	240,006
Total available-for-sale securities	$	240,617	$	240,006

Balance Sheet Components

3 Months Ended

Mar. 31, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Balance Sheet Components

5. Balance Sheet Components

Property and Equipment, Net

Property and equipment consisted of the following (in thousands):


	March 31, 2022			December 31, 2021
Leasehold improvements	$	3,268		$	3,268
Furniture, laboratory and office equipment		3,431			3,423
Computer equipment		244			244
Total property and equipment		6,943			6,935
Less accumulated depreciation and amortization		(3,902	)		(3,652	)
Property and equipment, net	$	3,041		$	3,283

Depreciation expense was $0.3 million and $0.2 million for each of the three months ended March 31, 2022 and 2021, respectively.

Accrued and Other Current Liabilities

Accrued liabilities consisted of the following (in thousands):


	March 31, 2022		December 31, 2021
Accrued clinical costs	$	1,703	$	1,642
Accrued preclinical and research costs		1,129		1,043
Accrued employee-related costs		1,201		1,970
Accrued professional services		192		231
Other		153		99
Total accrued liabilities	$	4,378	$	4,985

Debt

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Debt

7. Debt

In November 2021, the Company entered into a loan agreement (the “Loan Agreement”) with Oxford Finance, LLC (“Oxford Finance”), which provides the Company up to $50.0 million in borrowing capacity across five potential tranches (each a “Term Loan,”

and collectively “Term Loans”). The initial tranche of $10.0 million was funded at the closing of the Loan Agreement, and an additional $10.0 million will be available at the Company’s election from July 1, 2022 to December 30, 2022. Subsequent tranches of $20.0 million each may become available upon achieving milestones related to the Company’s MISSION Phase 2 clinical trial and KZR-261 Phase 1 clinical trial, up to the aggregate maximum amount of $50.0 million. The loan facility is secured by all assets except intellectual property, which has a negative pledge, and will mature on November 1, 2026. There are no warrants or financial covenants associated with the Loan Agreement.

The Term Loans bear interest at a floating per annum rate (based on the actual number of days elapsed divided by a year of 360 days) equal to the sum of (a) the greater of (i) 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 and (ii) 0.08%, plus (b) 7.87%. The Company is required to make monthly interest-only payments prior to the amortization date of January 1, 2025, subject to a potential one-year extension upon satisfaction of certain conditions.

All unpaid principal and accrued and unpaid interest with respect to each Term Loan is due and payable in full on November 1, 2026 (the “Maturity Date”). The Company has the option to prepay the outstanding balance prior to maturity, subject to a prepayment fee of 1.0% to 2.0% depending upon when the prepayment occurs. Upon repayment of the Term Loans, the Company is required to make a final payment fee to the lenders equal to 6.5% of the original principal amount of the Term Loans funded which will be accrued by charges to interest expense over the term of the loans using the effective interest method.

The Loan Agreement also includes subjective acceleration clauses which permit the lenders to accelerate the Maturity Date under certain circumstances, including, but not limited to, material adverse effects on a Company’s financial status or otherwise. As of March 31, 2022, the Company is in compliance with all covenants in the Loan Agreement.

Interest expense was $0.2 million for the three months ended March 31, 2022. The effective interest rate on the Term Loans, including the amortization of the debt discount and issuance costs, and accretion of the final payment, was 11%. The components of the long-term debt balance are as follows:


	March 31, 2022			December 31, 2021
Principal loan balance	$	10,000		$	10,000
Unamortized debt discount and issuance costs		(408	)		(431	)
Cumulative accretion of final fee		83			53
Long-term debt, net	$	9,675		$	9,622

As of March 31, 2022, the estimated future principal payments due were as follows:


Years Ending December 31,
2022	$	—
2023		—
2024		—
2025		5,217
2026		4,783
Total	$	10,000

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-Name Accounting Standards Codification
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+ Details

Lease

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Lease

6. Lease

In August 2017, the Company entered into a lease agreement to lease 24,357 square feet of combination laboratory and office space in South San Francisco, California. This lease expires in February 2025.

Information related to the Company’s ROU asset and related lease liabilities were as follows (in thousands):


	Three months ended March 31, 2022
Cash paid for operating lease liabilities	$	283
Operating lease costs		275
Variable lease costs		111

Maturities of lease liabilities as of March 31, 2022 were as follows for the years ending December 31:
2022		1,197
2023		1,635
2024		1,684
2025		282
Total undiscounted lease payments		4,798
Less: imputed interest		(659	)
Total lease liabilities	$	4,139

Operating lease liabilities, current		1,241
Operating lease liabilities, noncurrent		2,898
Total operating lease liabilities	$	4,139

Pre-Funded Warrants

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Pre-Funded Warrants

. Pre-Funded Warrants

In February 2020, the Company completed an underwritten public offering of 18,965,385 shares of its common stock at a purchase price of $2.60 per share and, to certain investors in lieu thereof, pre-funded warrants to purchase 2,884,615 shares of its common stock at a purchase price of $2.599 per underlying share.

In June 2020, the Company completed an underwritten public offering of 7,590,909 shares of its common stock at a purchase price of $5.50 per share and, to certain investors in lieu thereof, pre-funded warrants to purchase 909,091 shares of its common stock at purchase price of $5.499 per underlying share.

Each pre-funded warrant entitles the holder to purchase shares of common stock at an exercise price of $0.001 per share and expires 20 years from the date of issuance. These warrants were recorded as a component of stockholders’ equity within additional paid-in capital. Per the terms of the warrant agreement, a holder of the outstanding warrant is not entitled to exercise any portion of the pre-funded warrant if, upon exercise of such portion of the warrant, the holder’s ownership of our common stock (together with its affiliates) or the combined voting power of our securities beneficially owned by such holder (together with its affiliates) would exceed 4.99% after giving effect to the exercise (“Maximum Ownership Percentage”). Upon at least 61 days’ prior notice to us by the warrant

holder, any warrant holder may increase or decrease the Maximum Ownership Percentage to any other percentage not to exceed 19.99%. As of March 31, 2022, no shares underlying the pre-funded warrants have been exercised.

The following table represents a summary of the pre-funded warrants outstanding as of March 31, 2022:

Issue Date

Classification

Exercise Price

Expiration Date

Number of shares underlying

February 4, 2020

Equity

0.001

February 4, 2040

2,884,615

June 11, 2020

Equity

0.001

June 11, 2040

909,091

Total Outstanding

3,793,706

- Definition

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

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+ Details

Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

. Stock-Based Compensation

Stock Incentive Plans

2018 Equity Incentive Plan

In June 2018, the Company’s board of directors adopted and its stockholders approved the 2018 Equity Incentive Plan (the “2018 Plan”), which became effective as of June 20, 2018, at which point no further grants could be made under the 2015 Equity Incentive Plan (the “2015 Plan”) described below. Under the 2018 Plan, the Company may grant incentive stock options (“ISOs”), nonstatutory stock options (“NSOs”), stock appreciation rights, restricted stock awards, restricted stock units (“RSUs”) and other stock-based awards. As of March 31, 2022, options to purchase 7,335,156 shares of common stock were outstanding and 1,434,652 shares were available for future issuance under the 2018 Plan.

Initially, subject to adjustment as provided in the 2018 Plan, the aggregate number of shares of the Company’s common stock authorized for issuance pursuant to stock awards under the 2018 Plan was 4,000,000 shares, which is the sum of (i) 1,600,692 shares plus (ii) the number of shares reserved and available for issuance under the 2015 Plan at the time the 2018 Plan became effective and (iii) the number of shares subject to stock options or other stock awards granted under the 2015 Plan that expire, terminate are forfeited or otherwise not issued, or are withheld to satisfy a tax withholding obligation in connection with an award or to satisfy a purchase or exercise price of an award (such as upon the expiration or termination of a stock award prior to vesting). The number of shares of the Company’s common stock reserved for issuance under the 2018 Plan automatically increases on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, by 5% of the total number of shares of capital stock outstanding on December 31 of the preceding calendar year, or a lesser number of shares determined by the Company’s board of directors prior to such increase. The maximum number of shares that may be issued upon the exercise of ISOs under the 2018 Plan is 12,500,000 shares.

2015 Equity Incentive Plan

The Company’s 2015 Plan provided for the granting of ISOs and NSOs to employees, directors and consultants at the discretion of its board of directors. The 2015 Plan was terminated as to future awards in June 2018, although it continues to govern the terms of options that remain outstanding under the 2015 Plan.

No additional stock awards will be granted under the 2015 Plan, and all outstanding stock awards granted under the 2015 Plan that are repurchased, forfeited, expire or are cancelled will become available for grant under the 2018 Plan in accordance with its terms.

Options granted under the 2015 Plan expire no later than 10 years from the date of grant. Options granted under the 2015 Plan vest over periods determined by the Company’s board of directors, generally over four years. The 2015 Plan allows for early exercise of certain options prior to vesting. Upon termination of employment, the unvested shares are subject to repurchase at the original exercise price. As of March 31, 2022, options to purchase 1,597,058 shares of common stock were outstanding under the 2015 Plan.

2018 Employee Stock Purchase Plan

In June 2018, the Company’s board of directors adopted and its stockholders approved the 2018 Employee Stock Purchase Plan (the “ESPP”), which became effective as of June 20, 2018. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the U.S. Internal Revenue Code of 1986, as amended. The number of shares of common stock initially reserved for issuance under the ESPP was 200,000 shares. The ESPP provides for an annual increase on January 1 of each year, beginning on January 1, 2019 and continuing through and including January 1, 2028, equal to the lesser of (i) 1% of the shares of common stock outstanding on the last day of the prior fiscal year or (ii) 375,000 shares, or a lesser number of shares determined by the Company’s board of directors prior to such increase. As of March 31, 2022, 246,232 shares of common stock had been issued under the ESPP and 1,086,992 shares remained available for future issuance under the ESPP. The price per share of common stock to be paid by an ESPP participant on the applicable purchase date of an offering period shall be equal to 85% of the lesser of the fair market value of a share of common stock on (i) the applicable offering date or (ii) the applicable purchase date. The Company’s board of directors authorized an initial six-month offering period beginning on November 16, 2018 and ending on May 15, 2019. The Company’s board of directors has subsequently authorized additional six-month offering periods, with the most recent offering period beginning on November 16, 2021.

Stock Option Activity

The following table summarizes activity under the Company’s stock option plans and related information (in thousands, except share and per share amounts):


	Number of Options Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2021		6,945,184		$	5.95		7.9	$	77,363
Options granted		2,078,335		$	14.44
Options exercised		(59,174	)	$	3.52			$	720
Options cancelled/forfeited		(32,131	)	$	7.01
Outstanding at March 31, 2022		8,932,214		$	7.94		8.2	$	80,154
Vested and exercisable at March 31, 2022		3,696,826		$	6.07		6.8	$	41,062

The weighted average grant date fair value of options granted during the three months ended March 31, 2022 was $10.46 per share. The aggregate intrinsic value of exercised stock options during the three months ended March 31, 2022 was $0.7 million. The aggregate intrinsic value is calculated as the difference between the exercise price and the estimated fair value of the Company’s common stock at the date of exercise.

Restricted Stock Units Granted to Employees

During the three months ended March 31, 2022, the Company granted RSUs to certain employees pursuant to the 2018 Plan. One-third of each RSU grant will vest annually following the vesting commencement dates, over a vesting period of 3 years. RSUs are awards that entitle the holder to receive freely tradable shares of the Company's common stock upon vesting and are not forfeitable once fully vested. The valuations for these RSUs were based on the closing prices of the Company's common stock on the grant dates and recognized as stock-based compensation expenses over the respective vesting terms.


	Number of RSUs Outstanding			Weighted Average Grant-Date Fair Price
Outstanding at December 31, 2021		—			—
RSUs granted		43,135		$	14.55
RSUs vested		—		$	—
RSUs forfeited		(1,200	)	$	14.55
Outstanding at March 31, 2022		41,935		$	14.55

Stock-Based Compensation Expense

Total stock-based compensation expense recognized by function was as follows (in thousands):


	Three Months Ended March 31,
	2022		2021
Research and development	$	1,323	$	782
General and administrative		1,781		1,146
Total stock-based compensation expense	$	3,104	$	1,928

As of March 31, 2022, the unrecognized stock-based compensation cost related to outstanding unvested stock options and RSUs that are expected to vest was $33.9 million with an estimated weighted average amortization period of 2.9 years.

The fair value of the stock options granted is calculated using the Black-Scholes option-pricing model with the following range of assumptions:


	Three Months Ended March 31,
	2022		2021
Expected term (years)	5.3 - 6.0		6.0
Expected volatility	84.6 - 86.8	%	88.0 - 88.1	%
Risk-free interest rate	1.6 - 2.1	%	0.5 - 0.9	%
Expected dividend yield	—		—

The expected term of options granted represents the period of time that options granted are expected to be outstanding and was determined by calculating the midpoint between the date of vesting and the contractual life of each option. The expected term of the ESPP rights is equal to the six-month look-back period. Volatility is based on the average of the historical volatility of the Company's stock price and that of a peer group of public companies over the expected term. The peer group was selected on the basis of operational and economic similarity with the Company’s principal business operations. The risk-free interest rate for the expected term of the options is based on the U.S. Treasury yield curve with a maturity equal to the expected term in effect at the time of grant. The Company has not paid, and does not anticipate paying, cash dividends on its shares of common stock; therefore, the expected dividend yield is zero.

Income Taxes

3 Months Ended

Mar. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

. Income Taxes

No provision for income taxes was recorded for the three months ended March 31, 2022 and 2021, respectively. Deferred tax assets generated from the Company’s net operating losses have been fully reserved, as the Company believes it is not more likely than not that the benefit will be realized.

Effective January 1, 2022, under the Tax Cuts and Jobs Act, for tax purposes the Company is required to capitalize and subsequently amortize all R&D expenditures over five years for research activities conducted in the U.S. and over fifteen years for research activities conducted outside of the U.S. Given the significant loss and credit carryforwards in the U.S., the Company does not anticipate to have a change in valuation allowance assertion.

In December 2015, the Protecting Americans from Tax Hikes Act of 2015 (the “PATH Act”) was signed into law, which created several new research and development (“R&D”) tax credit provisions, including allowing qualified small businesses to utilize the R&D credit against the employer’s portion of payroll tax up to a maximum of $250,000 per year. The Company qualified as a small business under the PATH Act for 2016 through 2020. During the three months ended March 31, 2022 and 2021, the Company utilized $79,000 and $154,000 of R&D tax credits as a reduction of payroll expenses to offset its payroll tax liabilities, respectively. All R&D tax credits have been fully utilized as of March 31, 2022.

- Definition

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

+ References

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+ Details

Net Loss per Share

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Net Loss Per Share

11. Net Loss Per Share

Net Loss Per Share

The following table sets forth the calculation of basic and diluted net loss per share during the periods presented (in thousands, except share and per share data):


	Three Months Ended March 31,
	2022			2021
Numerator:
Net loss	$	(16,024	)	$	(12,994	)
Denominator:
Weighted-average shares of common stock outstanding		60,630,389			51,058,039
Net loss per share, basic and diluted	$	(0.26	)	$	(0.25	)

Basic net loss per common share is calculated by dividing net loss by the weighted-average number of shares of common stock and pre-funded warrants outstanding during the period, without consideration of common share equivalents. Diluted net loss per common share is computed by dividing net loss by the weighted-average number of shares of common stock, pre-funded warrants and common share equivalents outstanding for the period. The pre-funded warrants are included in the computation of basic and diluted net loss per common share as the exercise price is negligible and the pre-funded warrants are fully vested and exercisable. Common share equivalents are only included in the calculation of diluted net loss per common share when their effect is dilutive.

Potential dilutive securities, which include, vested and unvested options to purchase common stock and unvested common stock outstanding that were exercised early have been excluded from the computation of diluted net loss per share as the effect is antidilutive. Therefore, the denominator used to calculate both basic and diluted net loss per common share is the same in all periods presented.

The following outstanding shares of common stock equivalents were excluded from the computation of the diluted net loss per share for the periods presented because their effect would have been anti-dilutive:


	Three Months Ended March 31,
	2022		2021
Stock options to purchase common stock		8,932,214		7,149,840
Restricted stock units subject to future vesting		41,935		—
Common stock subject to future vesting		—		5,904
Total		8,974,149		7,155,744

Subsequent Event

3 Months Ended

Mar. 31, 2022

Subsequent Events [Abstract]

Subsequent Event

12. Subsequent Event

In April 2022, the Company adopted the Kezar Life Sciences, Inc. 2022 Inducement Plan (the “Inducement Plan”), which is a non-stockholder approved stock plan adopted pursuant to the “inducement exception” provided under Nasdaq Listing Rule 5635(c)(4), for the award of nonstatutory stock options, restricted stock units and other equity awards as permitted by the Inducement Plan (collectively, “Inducement Awards”) to persons not previously an employee or director of the Company, or following a bona fide period of non-employment, as an inducement material to such persons entering into employment with the Company (“Eligible Recipients”). Under the Inducement Plan, the Company may grant up to 3,000,000 shares of Common Stock in the form of Inducement Awards to Eligible Recipients in compliance with the requirements of Nasdaq Listing Rule 5635(c)(4).

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2022
Accounting Policies [Abstract]
Basis of presentation and consolidation	Basis of Presentation and Consolidation The condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) and include the Company’s accounts and those of its wholly owned Australian subsidiary, Kezar Life Sciences Australia Pty Ltd., which is a proprietary company limited by shares. All intercompany balances and transactions have been eliminated upon consolidation. The condensed consolidated balance sheet at December 31, 2021 has been derived from the audited consolidated financial statements at that date but does not include all information and footnotes required by GAAP for complete financial statements. These unaudited condensed consolidated financial statements should be read in conjunction with the audited financial statements included in the Annual Report.
Unaudited Condensed Consolidated Financial Statements	Unaudited Condensed Consolidated Financial Statements The accompanying financial information as of March 31, 2022 is unaudited. The interim condensed consolidated financial statements included in this report reflect all adjustments (consisting only of normal recurring adjustments) that our management considers necessary for the fair statement of the results of operations for the interim periods covered and of our financial condition at the date of the interim balance sheet. The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with GAAP for interim financial information. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. The results for interim periods are not necessarily indicative of the results for the entire year or any other interim period. The accompanying condensed consolidated financial statements and related financial information should be read in conjunction with the audited financial statements and the related notes thereto included in our Annual Report.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the reporting period. Significant items subject to such estimates and assumptions include the stock-based compensation, and accrued research and development costs. Management bases its estimates on historical experience and on various other market-specific relevant assumptions that management believes to be reasonable under the circumstances. Actual results may differ from those estimates. The Company anticipates that the ongoing COVID-19 pandemic, recent geopolitical events and supply-chain concerns could have an impact on our clinical development timelines. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgment. As of the date of issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgments or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the consolidated financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s consolidated financial statements.
Significant Risks and Uncertainties	Significant Risks and Uncertainties The Company has implemented business continuity plans designed to address and mitigate the impact of the COVID-19 pandemic on its business. The extent to which the COVID-19 pandemic impacts the Company’s business, preclinical and clinical development and regulatory efforts, corporate development objectives and the value of and market for its common stock, will depend on future developments that are highly uncertain and cannot be predicted with confidence at this time, such as the ultimate duration of the pandemic, travel restrictions, quarantines, social distancing, safety measures and business closure requirements in the United States, Europe, China and other countries where we conduct clinical trials and/or manufacture our product candidates. The global economic slowdown, the overall disruption of global healthcare systems and the other risks and uncertainties associated with the pandemic, geopolitical events and global supply chains could have a material adverse effect on the Company’s business, financial condition, results of operations and growth prospects. In addition, the Company is subject to other challenges and risks specific to its business and its ability to execute on its strategy, as well as risks and uncertainties common to companies in the biotechnology industry with development operations, including, without limitation, risks and uncertainties associated with: obtaining regulatory feedback regarding the Company’s product candidates; delays or problems in the supply of its product candidates; loss of single source suppliers or their failure to comply with manufacturing regulations; identifying, acquiring or in-licensing additional technologies or product candidates; clinical development and the inherent uncertainty of clinical success; the challenges of protecting and enhancing its intellectual property rights; and complying with applicable regulatory requirements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements The Company continues to monitor new accounting pronouncements issued by the Financial Accounting Standards Board and does not believe any accounting pronouncements issued through the date of this report will have a material impact on the Company’s condensed consolidated financial statements.
Fair Value Measurements	Financial assets and liabilities are recorded at fair value. The carrying amount of certain financial instruments, including cash and cash equivalents, marketable securities, other current assets, accounts payable and accrued liabilities, approximate fair value due to their relatively short maturities. Assets and liabilities recorded at fair value on a recurring basis in the condensed consolidated 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. The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows: Level 1: Quoted prices in active markets for identical assets or liabilities. Level 2: Observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. 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. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The Company applies fair value accounting for all financial assets and liabilities and nonfinancial assets and liabilities that are required to be recognized or disclosed at fair value in the financial statements. The Company determines the fair value of Level 1 assets using quoted prices in active markets for identical assets. The Company reviews trading activity and pricing for Level 2 investments as of each measurement date. Level 2 inputs, which are obtained from various third-party data providers, represent quoted prices for similar assets in active markets and were derived from observable market data, or, if not directly observable, were derived from or corroborated by other observable market data.

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured at Fair Value on a Recurring Basis


	March 31, 2022
	Total		Level 1		Level 2		Level 3
Financial Assets:
U.S. Treasury money market funds	$	22,334	$	22,334	$	—	$	—
U.S. Treasury securities		141,731		141,731		—		—
Commercial paper		74,744		—		74,744		—
U.S. agency bonds		1,197		—		1,197		—
Total	$	240,006	$	164,065	$	75,941	$	—


	December 31, 2021
	Total		Level 1		Level 2		Level 3
Financial Assets:
U.S. Treasury money market funds	$	60,375	$	60,375	$	—	$	—
U.S. Treasury securities		82,106		82,106		—		—
Commercial paper		46,687		—		46,687		—
Corporate debt securities		15,481		—		15,481		—
U.S. agency bonds		1,199		—		1,199		—
Total	$	205,848	$	142,481	$	63,367	$	—

Available-for-Sale Securities (Tables)

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

Summary of Available-For-Sale Securities Recorded in Cash and Cash Equivalents or Marketable Securities


	March 31, 2022
Financial Assets	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury money market funds	$	22,334	$	—	$	—		$	22,334
U.S. Treasury securities		142,185		—		(454	)		141,731
Commercial paper		74,898		—		(154	)		74,744
U.S. agency bonds		1,200		—		(3	)		1,197
Total	$	240,617	$	—	$	(611	)	$	240,006


	December 31, 2021
Financial Assets	Amortized Cost		Unrealized Gains		Unrealized Losses			Fair Value
U.S. Treasury money market funds	$	60,375	$	—	$	—		$	60,375
U.S. Treasury securities		82,204		—		(98	)		82,106
Commercial paper		46,678		13		(4	)		46,687
Corporate debt securities		15,486		—		(5	)		15,481
U.S. agency bonds		1,200		—		(1	)		1,199
Total	$	205,943	$	13	$	(108	)	$	205,848

Summary of Gross Unrealized Losses and Fair Value by Major Security Type for Available-For-Sale Securities in Unrealized Loss Position


	March 31, 2022					December 31, 2021
	Less than 12 consecutive months					Less than 12 consecutive months
	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
U.S. Treasury securities	$	141,731	$	(454	)	$	82,106	$	(98	)
Commercial paper	$	74,744	$	(154	)		13,734		(4	)
Corporate debt securities		—		—			15,481		(5	)
U.S. agency bonds		1,197		(3	)		1,199		(1	)
Total	$	217,672	$	(611	)	$	112,520	$	(108	)

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

As of March 31, 2022, the amortized cost and estimated fair value of the Company’s available-for-sale securities by contractual maturity are shown below (in thousands):


	Amortized		Estimated
Available-for-sale securities maturing:	Cost		Fair Value
In one year or less	$	240,617	$	240,006
Total available-for-sale securities	$	240,617	$	240,006

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Property and Equipment

Property and equipment consisted of the following (in thousands):


	March 31, 2022			December 31, 2021
Leasehold improvements	$	3,268		$	3,268
Furniture, laboratory and office equipment		3,431			3,423
Computer equipment		244			244
Total property and equipment		6,943			6,935
Less accumulated depreciation and amortization		(3,902	)		(3,652	)
Property and equipment, net	$	3,041		$	3,283

Accrued and Other Current Liabilities

Accrued liabilities consisted of the following (in thousands):


	March 31, 2022		December 31, 2021
Accrued clinical costs	$	1,703	$	1,642
Accrued preclinical and research costs		1,129		1,043
Accrued employee-related costs		1,201		1,970
Accrued professional services		192		231
Other		153		99
Total accrued liabilities	$	4,378	$	4,985

Debt (Tables)

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Schedule of Long-term Debt Balance

The components of the long-term debt balance are as follows:


	March 31, 2022			December 31, 2021
Principal loan balance	$	10,000		$	10,000
Unamortized debt discount and issuance costs		(408	)		(431	)
Cumulative accretion of final fee		83			53
Long-term debt, net	$	9,675		$	9,622

Schedule of Estimated Future Principal Payments

As of March 31, 2022, the estimated future principal payments due were as follows:


Years Ending December 31,
2022	$	—
2023		—
2024		—
2025		5,217
2026		4,783
Total	$	10,000

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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+ Details

Lease (Tables)

3 Months Ended

Mar. 31, 2022

Leases [Abstract]

Details of Right-of-Use Assets and Lease Liabilities

Information related to the Company’s ROU asset and related lease liabilities were as follows (in thousands):


	Three months ended March 31, 2022
Cash paid for operating lease liabilities	$	283
Operating lease costs		275
Variable lease costs		111

Maturities of lease liabilities as of March 31, 2022 were as follows for the years ending December 31:
2022		1,197
2023		1,635
2024		1,684
2025		282
Total undiscounted lease payments		4,798
Less: imputed interest		(659	)
Total lease liabilities	$	4,139

Operating lease liabilities, current		1,241
Operating lease liabilities, noncurrent		2,898
Total operating lease liabilities	$	4,139

Pre-Funded Warrants (Tables)

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Summary of Pre-Funded Warrants Outstanding

The following table represents a summary of the pre-funded warrants outstanding as of March 31, 2022:

Issue Date

Classification

Exercise Price

Expiration Date

Number of shares underlying

February 4, 2020

Equity

0.001

February 4, 2040

2,884,615

June 11, 2020

Equity

0.001

June 11, 2040

909,091

Total Outstanding

3,793,706

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Activity under Stock Option Plans and Related Information

The following table summarizes activity under the Company’s stock option plans and related information (in thousands, except share and per share amounts):


	Number of Options Outstanding			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (Years)		Aggregate Intrinsic Value
Outstanding at December 31, 2021		6,945,184		$	5.95		7.9	$	77,363
Options granted		2,078,335		$	14.44
Options exercised		(59,174	)	$	3.52			$	720
Options cancelled/forfeited		(32,131	)	$	7.01
Outstanding at March 31, 2022		8,932,214		$	7.94		8.2	$	80,154
Vested and exercisable at March 31, 2022		3,696,826		$	6.07		6.8	$	41,062

Summary of RSU Activity


	Number of RSUs Outstanding			Weighted Average Grant-Date Fair Price
Outstanding at December 31, 2021		—			—
RSUs granted		43,135		$	14.55
RSUs vested		—		$	—
RSUs forfeited		(1,200	)	$	14.55
Outstanding at March 31, 2022		41,935		$	14.55

Stock-Based Compensation Expense Recognized

Total stock-based compensation expense recognized by function was as follows (in thousands):


	Three Months Ended March 31,
	2022		2021
Research and development	$	1,323	$	782
General and administrative		1,781		1,146
Total stock-based compensation expense	$	3,104	$	1,928

Fair Value of Employee Stock Options Granted is Calculated Using Black Scholes Option Pricing Model with Range of Assumptions

The fair value of the stock options granted is calculated using the Black-Scholes option-pricing model with the following range of assumptions:


	Three Months Ended March 31,
	2022		2021
Expected term (years)	5.3 - 6.0		6.0
Expected volatility	84.6 - 86.8	%	88.0 - 88.1	%
Risk-free interest rate	1.6 - 2.1	%	0.5 - 0.9	%
Expected dividend yield	—		—

Net Loss per Share (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Calculation of Basic and Diluted Net Loss per Share

The following table sets forth the calculation of basic and diluted net loss per share during the periods presented (in thousands, except share and per share data):


	Three Months Ended March 31,
	2022			2021
Numerator:
Net loss	$	(16,024	)	$	(12,994	)
Denominator:
Weighted-average shares of common stock outstanding		60,630,389			51,058,039
Net loss per share, basic and diluted	$	(0.26	)	$	(0.25	)

Anti-dilutive Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share


	Three Months Ended March 31,
	2022		2021
Stock options to purchase common stock		8,932,214		7,149,840
Restricted stock units subject to future vesting		41,935		—
Common stock subject to future vesting		—		5,904
Total		8,974,149		7,155,744

Organization and Description of the Business - Additional Information (Details) $ / shares in Units, $ in Thousands			1 Months Ended		3 Months Ended
	Jun. 11, 2020 shares	Feb. 04, 2020 shares	Apr. 30, 2022 USD ($) $ / shares shares	Dec. 31, 2021 USD ($)	Mar. 31, 2022 USD ($) Segment $ / shares shares
Organization And Description Of Business [Line Items]
Number of operating segments \| Segment					1
Accumulated deficit				$ 180,654	$ 196,678
ATM Agreement \| Subsequent Event
Organization And Description Of Business [Line Items]
Weighted average purchase price, per share \| $ / shares			$ 16.82
Issuance of common stock \| shares			820,000
Net proceeds from the public offering			$ 13,400
ATM Agreement \| Cowen and Company LLC
Organization And Description Of Business [Line Items]
Percentage of commission on gross sales proceeds of issuance of common stock				3.00%
Weighted average purchase price, per share \| $ / shares					$ 15.45
Issuance of common stock \| shares					3,245,738
Net proceeds from the public offering					$ 48,600
Underwritten Public Offering
Organization And Description Of Business [Line Items]
Issuance of common stock \| shares	7,590,909	18,965,385
Minimum
Organization And Description Of Business [Line Items]
Sufficient cash and cash equivalents available period term					12 months
Maximum \| ATM Agreement \| Cowen and Company LLC
Organization And Description Of Business [Line Items]
Common stock aggregate offering price				$ 200,000

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	$ 240,006	$ 205,848
Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	164,065	142,481
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	75,941	63,367
U.S. Treasury Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	22,334	60,375
U.S. Treasury Money Market Funds \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	22,334	60,375
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	141,731	82,106
U.S. Treasury Securities \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	141,731	82,106
Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	74,744	46,687
Commercial paper \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	74,744	46,687
Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets		15,481
Corporate debt securities \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets		15,481
U.S. agency bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	1,197	1,199
U.S. agency bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Financial Assets	$ 1,197	$ 1,199

Available-for-Sale Securities - Summary of Available-For-Sale Securities Recorded in Cash and Cash Equivalents or Marketable Securities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	$ 240,617
Fair Value	240,006
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	240,617	$ 205,943
Unrealized Gains		13
Unrealized Losses	(611)	(108)
Fair Value	240,006	205,848
Fair Value, Measurements, Recurring \| U.S. Treasury Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	22,334	60,375
Fair Value	22,334	60,375
Fair Value, Measurements, Recurring \| U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	142,185	82,204
Unrealized Losses	(454)	(98)
Fair Value	141,731	82,106
Fair Value, Measurements, Recurring \| Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	74,898	46,678
Unrealized Gains		13
Unrealized Losses	(154)	(4)
Fair Value	74,744	46,687
Fair Value, Measurements, Recurring \| Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost		15,486
Unrealized Losses		(5)
Fair Value		15,481
Fair Value, Measurements, Recurring \| U.S. agency bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Amortized Cost	1,200	1,200
Unrealized Losses	(3)	(1)
Fair Value	$ 1,197	$ 1,199

Available-for-Sale Securities - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Investments Debt And Equity Securities [Abstract]
Allowance for credit losses on securities in unrealized loss position	$ 0	$ 0
Sale of available-for-sale securities	$ 0

Available-for-Sale Securities - Summary of Gross Unrealized Losses and Fair Value by Major Security Type for Available-For-Sale Securities in Unrealized Loss Position (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	$ 217,672	$ 112,520
Unrealized Losses	(611)	(108)
U.S. Treasury Securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	141,731	82,106
Unrealized Losses	(454)	(98)
Commercial paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	74,744	13,734
Unrealized Losses	(154)	(4)
Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	0	15,481
Unrealized Losses	0	(5)
U.S. agency bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value	1,197	1,199
Unrealized Losses	$ (3)	$ (1)

Available-for-Sale Securities - Summary of Amortized Cost and Estimated Fair Value of Available-for-sale Securities by Contractual Maturity (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Available-for-sale securities maturing, Amortized Cost:
In one year or less, Amortized Cost	$ 240,617
Amortized Cost	240,617
Available-for-sale securities maturing, Estimated Fair Value:
In one year or less, Estimated Fair Value	240,006
Total available-for-sale securities, Estimated Fair Value	$ 240,006

Balance Sheet Components - Property and Equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Property Plant And Equipment [Line Items]
Total property and equipment	$ 6,943	$ 6,935
Less accumulated depreciation and amortization	(3,902)	(3,652)
Property and equipment, net	3,041	3,283
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	3,268	3,268
Furniture, Laboratory and Office Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	3,431	3,423
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 244	$ 244

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Depreciation expense	$ 0.3	$ 0.2

Balance Sheet Components - Accrued and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accrued preclinical and research costs	$ 1,129	$ 1,043
Accrued clinical costs	1,703	1,642
Accrued employee-related costs	1,201	1,970
Accrued professional services	192	231
Other	153	99
Total accrued liabilities	$ 4,378	$ 4,985

Debt - Additional Information (Details) - Loan And Security Agreement - Oxford Finance L L C $ in Millions	1 Months Ended	3 Months Ended
	Nov. 30, 2021 USD ($) Tranche	Mar. 31, 2022 USD ($)
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 50.0
Number of tranches \| Tranche	5
Line of credit facility, Maturity period	Nov. 01, 2026
Line of credit facility frequency of payments		monthly interest-only payments
Line of credit facility, extension period	1 year
Final payment fee percentage	6.50%
Interest expense		$ 0.2
Effective interest rate percentage	11.00%
Minimum
Debt Instrument [Line Items]
Prepayment fee percentage	1.00%
Maximum
Debt Instrument [Line Items]
Prepayment fee percentage	2.00%
Tranche One
Debt Instrument [Line Items]
Current borrowing capacity	$ 10.0
Tranche Two
Debt Instrument [Line Items]
Current borrowing capacity	10.0
Tranche, available period		July 1, 2022 to December 30, 2022
Tranche Three
Debt Instrument [Line Items]
Current borrowing capacity	$ 20.0
Equal To Sum Of A \| Floor Rate
Debt Instrument [Line Items]
Line of credit facility, additional interest rate	0.08%
Equal To Sum Of B
Debt Instrument [Line Items]
Line of credit facility, interest rate	7.87%

Debt - Schedule of Long-term Debt Balance (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Debt Disclosure [Abstract]
Principal loan balance	$ 10,000	$ 10,000
Unamortized debt discount and issuance costs	(408)	(431)
Cumulative accretion of final fee	83	53
Long-term debt, net	$ 9,675	$ 9,622

Debt - Schedule of Estimated Future Principal Payments (Details) $ in Thousands	Mar. 31, 2022 USD ($)
Debt Disclosure [Abstract]
2025	$ 5,217
2026	4,783
Total	$ 10,000

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References + Details

Lease - Additional Information (Details) - South San Francisco, California [Member]	3 Months Ended
	Mar. 31, 2022 ft²
Area of lease	24,357
Lease expiration date	Feb. 28, 2025

Lease - Details of Right-of-Use Assets and Lease Liabilities (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Lessee Disclosure [Abstract]
Cash paid for operating lease liabilities	$ 283	$ 245
Operating lease costs	275
Variable lease costs	111
2022	1,197
2023	1,635
2024	1,684
2025	282
Total undiscounted lease payments	4,798
Less: imputed interest	(659)
Total lease liabilities	4,139
Operating lease liabilities, current	1,241		$ 1,199
Operating lease liabilities, noncurrent	2,898		$ 3,223
Total operating lease liabilities	$ 4,139

Pre-Funded Warrants - Additional Information (Details) - $ / shares	Jun. 11, 2020	Feb. 04, 2020	Mar. 31, 2022	Jun. 30, 2020	Feb. 29, 2020
Class Of Warrant Or Right [Line Items]
Pre funded warrants to purchase shares of common stock	909,091	2,884,615	3,793,706
Pre funded warrants exercise price	$ 0.001	$ 0.001	$ 0.001
Pre-funded warrants, term			20 years
Maximum ownership percentage, not to exceed upon exercise of warrants			4.99%
Maximum ownership percentage, increase or decrease upon prior notice			19.99%
Pre-funded warrants exercised			0
February Offering
Class Of Warrant Or Right [Line Items]
Pre funded warrants to purchase shares of common stock					2,884,615
June Offering
Class Of Warrant Or Right [Line Items]
Pre funded warrants to purchase shares of common stock				909,091
Underwritten Public Offering
Class Of Warrant Or Right [Line Items]
Issuance of common stock	7,590,909	18,965,385
Common stock, shares issued, price per share	$ 5.50	$ 2.60
Warrant issue price per share	$ 5.499	$ 2.599

Pre-Funded Warrants - Summary of Pre-Funded Warrants Outstanding (Details) - $ / shares	Jun. 11, 2020	Feb. 04, 2020	Mar. 31, 2022
Class Of Warrant Or Right [Line Items]
Issue Date	Jun. 11, 2020	Feb. 04, 2020
Exercise Price	$ 0.001	$ 0.001	$ 0.001
Expiration Date	Jun. 11, 2040	Feb. 04, 2040
Number of shares underlying warrants	909,091	2,884,615	3,793,706

Stock-Based Compensation - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Jun. 30, 2018
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options shares outstanding	8,932,214		6,945,184
Common stock, shares issued	59,564,659		56,259,747
Aggregate intrinsic value of exercised stock options	$ 720,000
Expected term		6 years
Payments of dividends of common stock	$ 0
Expected dividend yield	0.00%	0.00%
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	6 years
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	5 years 3 months 18 days
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term	6 months
Employee options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock-based compensation cost	$ 33,900,000
Estimated weighted average amortization period	2 years 10 months 24 days
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options shares outstanding	7,335,156
Shares available for future issuance	1,434,652
Number of shares will increase automatically through every year on specified date	--01-01
Number of shares increase automatically continuing through maximum period	beginning on January 1, 2019 and continuing through and including January 1, 2028
Weighted average grant date fair value of options granted	$ 10.46
2018 Equity Incentive Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of shares authorized available for issuance	1,600,692
Increase in number of shares reserved for issuance as percentage of total number of shares of capital stock outstanding on last date of preceding calendar year	5.00%
2018 Equity Incentive Plan \| Maximum \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of shares authorized available for issuance	4,000,000
2018 Equity Incentive Plan \| Incentive Stock Options \| Maximum \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Maximum number of shares issued upon exercise of incentive stock options	12,500,000
2018 Equity Incentive Plan \| RSU Member
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
option grant vesting period	3 years
2015 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
option grant vesting period	4 years
Options to purchase of common stock outstanding	1,597,058
2015 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted expiry period	10 years
2018 Employee Stock Purchase Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares available for future issuance	1,086,992			200,000
Common stock, shares issued	246,232
Authorized an offering beginning period	Nov. 16, 2018
Authorized an offering ending period	May 15, 2019
Authorized an additional offering beginning period	Nov. 16, 2021
2018 Employee Stock Purchase Plan \| Maximum \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of annual increase in number of common stock shares	1.00%
Annual increase in number of common stock shares	375,000
Option price per share of common stock at fair market value	85.00%

Stock-Based Compensation - Summary of Activity under Stock Option Plans and Related Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of options outstanding, Outstanding, Beginning balance	6,945,184
Number of options outstanding, Options granted	2,078,335
Number of options outstanding, Options exercised	(59,174)
Number of Options outstanding, Options cancelled/forfeited	(32,131)
Number of options outstanding, Outstanding, Ending balance	8,932,214	6,945,184
Number of options outstanding, options vested and exercisable	3,696,826
Weighted average exercise price, Outstanding, Beginning balance	$ 5.95
Weighted average exercise price, Options granted	14.44
Weighted average exercise price, Options exercised	3.52
Weighted average exercise price, Options cancelled/forfeited	7.01
Weighted average exercise price, Outstanding, Ending balance	7.94	$ 5.95
Weighted average exercise price, options vested and exercisable	$ 6.07
Weighted average remaining contractual term, (Years) Outstanding balance	8 years 2 months 12 days	7 years 10 months 24 days
Weighted average remaining contractual term, (Years) options vested and exercisable	6 years 9 months 18 days
Aggregate intrinsic value, Outstanding, Beginning balance	$ 77,363
Aggregate intrinsic value, Options exercised	720
Aggregate intrinsic value, Outstanding, Ending balance	80,154	$ 77,363
Aggregate intrinsic value, options vested and exercisable	$ 41,062

Stock-Based Compensation - Summary of RSU Activity (Details)	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average exercise price, Options cancelled/forfeited	$ 7.01
Weighted average exercise price, Outstanding, Ending balance	$ 7.94
RSU Member \| 2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, granted \| shares	43,135
Number of shares, vested \| shares	0
Number of shares, forfeited \| shares	1,200
Number of shares outstanding, ending balance \| shares	41,935
Weighted average exercise price, granted	$ 14.55
Weighted average exercise price, Options cancelled/forfeited	14.55
Weighted average exercise price, Outstanding, Ending balance	$ 14.55

Stock-Based Compensation - Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 3,104	$ 1,928
Research and Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,323	782
General and Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,781	$ 1,146

Stock-Based Compensation - Fair Value of Stock Options Granted is Calculated Using Black Scholes Option Pricing Model with Range of Assumptions (Details)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)		6 years
Expected volatility, Minimum	84.60%	88.00%
Expected volatility, Maximum	86.80%	88.10%
Risk-free interest rate, Minimum	1.60%	0.50%
Risk-free interest rate, Maximum	2.10%	0.90%
Expected dividend yield	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 3 months 18 days
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years

Income Taxes - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Dec. 31, 2015	Mar. 31, 2022	Mar. 31, 2021
Operating Loss Carryforwards [Line Items]
Provision for income taxes		$ 0	$ 0
Research and development tax credit utilized as reduction of payroll expenses		$ 79,000	$ 154,000
Research and development tax credit utilized against employer's portion of payroll tax	$ 250,000
U S [Member]
Operating Loss Carryforwards [Line Items]
Research and development activities amortize period		5 years
Non - U S [Member]
Operating Loss Carryforwards [Line Items]
Research and development activities amortize period		15 years

- Definition

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

+ References + Details

Net Loss Per Share - Calculation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss	$ (16,024)	$ (12,994)
Denominator:
Weighted-average shares of common stock outstanding	60,630,389	51,058,039
Net loss per common share, basic and diluted	$ (0.26)	$ (0.25)

- Definition

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

+ References

+ Details

Net Loss Per Share - Anti-dilutive Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss per Share (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	8,974,149	7,155,744
Stock Options to Purchase Common Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	8,932,214	7,149,840
Restricted Stock Units Subject To Future Vesting [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	41,935
Common stock subject to future vesting [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share		5,904

Subsequent Event - Additional Information (Details)	Apr. 30, 2022 shares
Subsequent Event [Member]
Subsequent Event [Line Items]
Shares granted	3,000,000