0000950170-24-057180 | 10-Q | XBRL Viewer

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Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	95,199,724	93,269,377
Common stock, shares outstanding	95,199,724	93,269,377

Stock-Based Compensation

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

8. Stock-Based Compensation

Equity Incentive Plans

The Company has issued stock-based awards from various equity incentive and stock purchase plans, as more fully described in Note 8—Stock-Based Compensation of the Company’s Notes to Consolidated Financial Statements section in its Annual Report on Form 10-K for the year ended December 31, 2023.

Equity Incentive Plans Activity

Stock Options

The following table summarizes stock option activity under the Company's equity incentive plans for the three months ended March 31, 2024:


						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Options			Price		Term		Value
						(In years)		(In thousands)
Balance outstanding as of December 31, 2023		4,686,577		$	14.11		7.9	$	11,712
Granted		2,241,000			9.99
Exercised		(1,626	)		4.44
Cancelled and forfeited		(34,602	)		12.94
Balance outstanding as of March 31, 2024		6,891,349		$	12.78		8.3	$	16,139
Exercisable as of March 31, 2024		2,617,844		$	14.76		6.8	$	9,011

The fair value of stock option awards granted for the periods indicated was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:


	Three Months Ended March 31,
	2024	2023
Expected term (years)	5.5–6.1	5.5–6.1
Expected volatility	89.4–90.4%	91.6–93.2%
Risk-free interest rate	3.8–4.1%	3.4–3.8%
Expected dividend	—	—

As of March 31, 2024, total unrecognized stock-based compensation expense related to unvested stock options was $34.8 million, which is expected to be recognized over a weighted-average period of 3.0 years.

RSU and PSUs

RSUs generally vest annually over a two or three-year period. PSUs generally contain performance conditions associated with corporate goals, such as achievement of certain development milestones, that vests upon achievement over a one to three-year period.

The following table summarizes RSU and PSU activity for the three months ended March 31, 2024:


	RSUs					PSUs
	Number of Shares			Weighted-Average Grant Date Fair Value per Share		Number of Shares			Weighted-Average Grant Date Fair Value per Share
Balance outstanding as of December 31, 2023		688,382		$	10.72		299,168		$	5.96
Granted		651,950			9.98		192,000			9.98
Vested		(157,172	)		13.43		(159,168	)		7.00
Canceled		(6,614	)		10.78		—			—
Balance outstanding as of March 31, 2024		1,176,546		$	9.95		332,000		$	7.79

As of March 31, 2024, total unrecognized stock-based compensation expense related to RSUs and PSUs was $12.3 million, which is expected to be recognized over a weighted-average period of 1.9 years.

Stock-Based Compensation

The Company recorded stock-based compensation expense for the periods indicated as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development	$	2,315	$	1,486
General and administrative		2,683		2,065
Total stock-based compensation	$	4,998	$	3,551

Balance Sheet Components (Tables)

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Prepaid and Other Current Assets

Prepaid and other current assets consist of the following as of the periods presented (in thousands):


	March 31, 2024		December 31, 2023
Prepaid research and development	$	9,009	$	11,579
Prepaid taxes		615		614
Prepaid other		2,870		2,471
Total prepaid and other current assets	$	12,494	$	14,664

Schedule of Accrued Expenses

Accrued expenses consist of the following as of the periods presented (in thousands):


	March 31, 2024		December 31, 2023
Accrued research and development expenses	$	15,881	$	13,017
Accrued employee and related expenses		2,603		6,248
Accrued professional and legal fees		1,776		1,110
Accrued other expenses		35		155
Total accrued expenses	$	20,295	$	20,530

Balance Sheet Components - Schedule of Prepaid and Other Current Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Prepaid Expense and Other Assets, Current [Abstract]
Prepaid research and development	$ 9,009	$ 11,579
Prepaid taxes	615	614
Prepaid other	2,870	2,471
Total prepaid and other current assets	$ 12,494	$ 14,664

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended
	Feb. 28, 2023	Mar. 31, 2023	Mar. 31, 2021	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Subsidiary Sale Of Stock [Line Items]
Offering costs				$ 253
Common stock, par value				$ 0.001		$ 0.001
Public Offerings
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of common stock, net of commissions and offering expenses		$ 296,800
Shares issued and sold		19,461,538
Offering price per share		$ 16.25			$ 16.25
Underwriting discounts and commissions		$ 19,000
Offering costs		$ 500
Public Offerings \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Shares issued and sold					19,461,538
2021 ATM Facility
Subsidiary Sale Of Stock [Line Items]
Selling commission per shares sold percentage			3.00%
Proceeds from issuance of common stock, net of commissions and offering expenses					$ 13,400
Shares issued and sold					968,000
Offering costs					$ 400
2021 ATM Facility \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Maximum value of common stock to be issued under agreement			$ 75,000
2023 ATM Facility
Subsidiary Sale Of Stock [Line Items]
Proceeds from issuance of common stock, net of commissions and offering expenses				$ 21,000
Shares issued and sold				1,396,888
Offering costs				$ 500
Common stock remaining for future sales				$ 104,400
2023 ATM Facility \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Maximum value of common stock to be issued under agreement	$ 150,000

Term Loan Facility - Schedule of Repayment of Principal Amount (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Disclosure [Abstract]
2024 (remaining nine months)	$ 0
2025	10,774
2026	13,036
2027	1,190
Total principal outstanding	25,000
Plus accumulated accretion of final payment fee	493
Less: unamortized debt discount	(536)
Total net carry value	24,957
Term loan, current	(1,892)	$ 0
Total term loan, noncurrent, net	$ 23,065	$ 24,795

Stock-Based Compensation - Summary of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 4,998	$ 3,551
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	2,315	1,486
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 2,683	$ 2,065

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured at Fair Value on Recurring Basis

The following tables present the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy for the periods indicated (in thousands):


		March 31, 2024
	Valuation	Amortized		Unrealized		Unrealized			Fair
	Hierarchy	Cost		Gains		Losses			Value
Money market funds	Level 1	$	4,073	$	—	$	—		$	4,073
Commercial paper	Level 2		124,016		—		(71	)		123,945
U.S. government bonds	Level 2		194,344		47		(377	)		194,014
Agency bonds	Level 2		53,252		10		(107	)		53,155
Corporate debt securities	Level 2		5,184		—		(22	)		5,162
U.S. Treasury securities	Level 2		49,505		—		(8	)		49,497
Total cash equivalents and marketable securities		$	430,374	$	57	$	(585	)	$	429,846
Classified as:
Cash equivalents									$	85,131
Marketable securities										344,715
Total cash equivalents and marketable securities									$	429,846


		December 31, 2023
	Valuation	Amortized		Unrealized		Unrealized			Fair
	Hierarchy	Cost		Gains		Losses			Value
Money market funds	Level 1	$	493	$	—	$	—		$	493
Commercial paper	Level 2		94,261		—		(55	)		94,206
U.S. government bonds	Level 2		137,976		250		(142	)		138,084
Agency bonds	Level 2		45,481		152		(44	)		45,589
Corporate debt securities	Level 2		3,177		—		(12	)		3,165
U.S. Treasury securities	Level 2		71,754		36		(1	)		71,789
Agency discount securities	Level 2		7,975		1		—			7,976
Total cash equivalents and marketable securities		$	361,117	$	439	$	(254	)	$	361,302
Classified as:
Cash equivalents									$	98,593
Marketable securities										262,709
Total cash equivalents and marketable securities									$	361,302

The valuation techniques used to measure the fair values of the Company’s Level 2 financial instruments, which generally have counterparties with high credit ratings, are based on quoted market prices when available. If quoted market prices are not available, the fair value for the security is estimated under the market or income approach using pricing models with market observable inputs.

Condensed Consolidated Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses:
Research and development	$ 47,428	$ 22,306
General and administrative	9,849	6,218
Total operating expenses	57,277	28,524
Loss from operations	(57,277)	(28,524)
Interest expense	(863)	(2,075)
Interest income and other, net	6,556	1,763
Net loss before income tax	(51,584)	(28,836)
Income tax expense	(97)	0
Net loss	(51,681)	(28,836)
Other comprehensive (loss) income:
Unrealized (loss) gain on marketable securities	(714)	114
Foreign currency translation adjustments	5	(4)
Total other comprehensive (loss) income	(709)	110
Comprehensive loss	$ (52,390)	$ (28,726)
Net loss per share, basic	$ (0.54)	$ (0.54)
Net loss per share, diluted	$ (0.54)	$ (0.54)
Weighted-average shares used to compute net loss per share, basic	95,846,740	53,171,370
Weighted-average shares used to compute net loss per share, diluted	95,846,740	53,171,370

Net Loss Per Share - Schedule of Weighted-average Shares Outstanding Used to Calculate Basic and Diluted Net Loss Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
The Weighted-average Shares Outstanding Used To Calculate Basic And Diluted Net Loss Per Share [Line Items]
Weighted-average shares used to compute net loss per share, basic	95,846,740	53,171,370
Weighted-average shares used to compute net loss per share, diluted	95,846,740	53,171,370
Common Stock
The Weighted-average Shares Outstanding Used To Calculate Basic And Diluted Net Loss Per Share [Line Items]
Weighted-average shares used to compute net loss per share, basic	93,965,659	52,371,370
Weighted-average shares used to compute net loss per share, diluted	93,965,659	52,371,370
Pre-funded Warrants
The Weighted-average Shares Outstanding Used To Calculate Basic And Diluted Net Loss Per Share [Line Items]
Weighted-average shares used to compute net loss per share, basic	1,881,081	800,000
Weighted-average shares used to compute net loss per share, diluted	1,881,081	800,000

Net Loss Per Share

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

9. Net Loss Per Share

The following table presents the weighted-average shares outstanding used to calculate basic and diluted net loss per share for the periods indicated:


	Three Months Ended March 31,
	2024		2023
Common stock		93,965,659		52,371,370
Pre-funded warrants		1,881,081		800,000
Total		95,846,740		53,171,370

The following outstanding potentially dilutive common stock equivalents have been excluded from the calculation of diluted net loss per share for the periods indicated due to their anti-dilutive effect:


	Three Months Ended March 31,
	2024		2023
Stock options outstanding		6,891,349		4,463,459
RSUs and PSUs outstanding		1,508,546		1,218,377
Warrants to purchase common stock		10,075,092		11,688,597
Conversion feature related to outstanding term loan		590,816		590,816
ESPP		13,091		7,721
Total		19,078,894		17,968,970

Stock-Based Compensation - Summary of Stock Option Activity (Details) - 2023 Inducement Plan and 2019 Employee Stock Purchase Plan - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Number of Options
Outstanding, Beginning Balance	4,686,577
Granted	2,241,000
Exercised	(1,626)
Cancelled and forfeited	(34,602)
Outstanding, Ending Balance	6,891,349	4,686,577
Exercisable as of of March 31, 2024	2,617,844
Weighted Average Exercise Price
Weighted Average Exercise Price Outstanding, Beginning Balance	$ 14.11
Weighted Average Exercise Price, Granted	9.99
Weighted Average Exercise Price, Exercised	4.44
Weighted Average Exercise Price, Cancelled and forfeited	12.94
Weighted Average Exercise Price Outstanding, Ending Balance	12.78	$ 14.11
Weighted Average Exercise Price, Exercisable as of March 31, 2024	$ 14.76
Weighted Average Remaining Contractual Term (In years)
Weighted Average Remaining Contractual Term (In years), Outstanding	8 years 3 months 18 days	7 years 10 months 24 days
Weighted Average Remaining Contractual Term (In years), Exercisable as of March 31, 2024	6 years 9 months 18 days
Aggregate Intrinsic Value
Aggregate Intrinsic Value	$ 16,139	$ 11,712
Aggregate Intrinsic Value, Exercisable as of March 31, 2024	$ 9,011

Organization and Liquidity

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Liquidity

1. Organization and Liquidity

Description of Business

89bio, Inc. (“89bio” or the “Company”) is a clinical-stage biopharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of liver and cardio-metabolic diseases. The Company’s lead product candidate, pegozafermin, a specifically engineered glycoPEGylated analog of fibroblast growth factor 21 (“FGF21”), is currently being developed for the treatment of metabolic dysfunction-associated steatohepatitis (“MASH”), previously known as nonalcoholic steatohepatitis, and for the treatment of severe hypertriglyceridemia (“SHTG”).

89bio was formed as a Delaware corporation in June 2019 to carry on the business of 89Bio Ltd., which was incorporated in Israel in January 2018.

Liquidity

The Company has incurred significant losses and negative cash flows from operations since inception and had an accumulated deficit of $509.1 million as of March 31, 2024. The Company has historically financed its operations primarily through the sale of equity securities, including warrants, and from borrowings under term loan facilities. To date, none of the Company’s product candidates have been approved for sale, and the Company has not generated any revenue from commercial products. The Company expects operating losses to continue and increase for the foreseeable future as the Company progresses its clinical development activities for its product candidates.

The Company believes its existing cash, cash equivalents and marketable securities of $562.3 million as of March 31, 2024 will be sufficient to fund its planned operating expense and capital expenditure requirements for a period of at least one year from the date of the issuance of these financial statements.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Summary of Stock Option Activity

The following table summarizes stock option activity under the Company's equity incentive plans for the three months ended March 31, 2024:


						Weighted
				Weighted		Average
				Average		Remaining		Aggregate
	Number of			Exercise		Contractual		Intrinsic
	Options			Price		Term		Value
						(In years)		(In thousands)
Balance outstanding as of December 31, 2023		4,686,577		$	14.11		7.9	$	11,712
Granted		2,241,000			9.99
Exercised		(1,626	)		4.44
Cancelled and forfeited		(34,602	)		12.94
Balance outstanding as of March 31, 2024		6,891,349		$	12.78		8.3	$	16,139
Exercisable as of March 31, 2024		2,617,844		$	14.76		6.8	$	9,011

Summary of Estimated Fair Value of Stock Option Awards Granted Using Black-Scholes Option-Pricing Model

The fair value of stock option awards granted for the periods indicated was estimated at the date of grant using a Black-Scholes option-pricing model with the following assumptions:


	Three Months Ended March 31,
	2024	2023
Expected term (years)	5.5–6.1	5.5–6.1
Expected volatility	89.4–90.4%	91.6–93.2%
Risk-free interest rate	3.8–4.1%	3.4–3.8%
Expected dividend	—	—

RSU and PSUs

Summary of Restricted Stock Unit Activity

The following table summarizes RSU and PSU activity for the three months ended March 31, 2024:


	RSUs					PSUs
	Number of Shares			Weighted-Average Grant Date Fair Value per Share		Number of Shares			Weighted-Average Grant Date Fair Value per Share
Balance outstanding as of December 31, 2023		688,382		$	10.72		299,168		$	5.96
Granted		651,950			9.98		192,000			9.98
Vested		(157,172	)		13.43		(159,168	)		7.00
Canceled		(6,614	)		10.78		—			—
Balance outstanding as of March 31, 2024		1,176,546		$	9.95		332,000		$	7.79

As of March 31, 2024, total unrecognized stock-based compensation expense related to RSUs and PSUs was $12.3 million, which is expected to be recognized over a weighted-average period of 1.9 years.

Stock-Based Compensation

Summary of Stock-Based Compensation Expense

The Company recorded stock-based compensation expense for the periods indicated as follows (in thousands):


	Three Months Ended March 31,
	2024		2023
Research and development	$	2,315	$	1,486
General and administrative		2,683		2,065
Total stock-based compensation	$	4,998	$	3,551

Commitments and Contingencies - Additional Information (Details) - Teva Agreements - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2018	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Nonrefundable upfront payment	$ 6.0
Payment upon achievement of certain clinical and commercial milestones	65.0
Asset transfer and license agreement, termination period after written notice		120 days
Asset transfer and license agreement, termination period notice of breach		60 days
Asset transfer and license agreement termination notice period if bankruptcy petition filed		60 days
Milestone payments			$ 2.5
Teva's Development Program
Loss Contingencies [Line Items]
Payment upon achievement of certain clinical and commercial milestones	$ 2.5

Term Loan Facility (Tables)

3 Months Ended

Mar. 31, 2024

Debt Disclosure [Abstract]

Schedule of Repayment of Principal Amount

The expected repayments of principal amount due on borrowings as of March 31, 2024 are as follows (in thousands):


2024 (remaining nine months)	$	—
2025		10,774
2026		13,036
2027		1,190
Total principal outstanding		25,000
Plus accumulated accretion of final payment fee		493
Less unamortized debt discount		(536	)
Total net carrying value		24,957
Term loan, current		(1,892	)
Term loan, noncurrent, net	$	23,065

Fair Value Measurements

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

The following tables present the Company’s financial assets measured at fair value on a recurring basis by level within the fair value hierarchy for the periods indicated (in thousands):


		March 31, 2024
	Valuation	Amortized		Unrealized		Unrealized			Fair
	Hierarchy	Cost		Gains		Losses			Value
Money market funds	Level 1	$	4,073	$	—	$	—		$	4,073
Commercial paper	Level 2		124,016		—		(71	)		123,945
U.S. government bonds	Level 2		194,344		47		(377	)		194,014
Agency bonds	Level 2		53,252		10		(107	)		53,155
Corporate debt securities	Level 2		5,184		—		(22	)		5,162
U.S. Treasury securities	Level 2		49,505		—		(8	)		49,497
Total cash equivalents and marketable securities		$	430,374	$	57	$	(585	)	$	429,846
Classified as:
Cash equivalents									$	85,131
Marketable securities										344,715
Total cash equivalents and marketable securities									$	429,846


		December 31, 2023
	Valuation	Amortized		Unrealized		Unrealized			Fair
	Hierarchy	Cost		Gains		Losses			Value
Money market funds	Level 1	$	493	$	—	$	—		$	493
Commercial paper	Level 2		94,261		—		(55	)		94,206
U.S. government bonds	Level 2		137,976		250		(142	)		138,084
Agency bonds	Level 2		45,481		152		(44	)		45,589
Corporate debt securities	Level 2		3,177		—		(12	)		3,165
U.S. Treasury securities	Level 2		71,754		36		(1	)		71,789
Agency discount securities	Level 2		7,975		1		—			7,976
Total cash equivalents and marketable securities		$	361,117	$	439	$	(254	)	$	361,302
Classified as:
Cash equivalents									$	98,593
Marketable securities										262,709
Total cash equivalents and marketable securities									$	361,302

The following table summarizes the estimated fair value of investments in marketable securities by effective contractual maturity dates as of March 31, 2024 (in thousands):


Within one year	$	314,373
After one year through two years		115,473
Total cash equivalents and marketable securities	$	429,846

As of March 31, 2024, the Company’s marketable securities in an unrealized loss position include primarily fixed-rate debt securities of varying maturities, which are sensitive to changes in the yield curve and other market conditions. Substantially all of the fixed-rate debt securities in a loss position are investment-grade debt securities. The Company has the intent and ability to hold such securities until recovery of the unrealized losses. Based on the Company’s assessment, the unrealized losses as of March 31, 2024 were primarily due to changes in interest rates and not due to increased credit risks associated with specific securities. No allowance for credit losses was recorded as of March 31, 2024 and December 31, 2023.

- 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

Subsequent Events

3 Months Ended

Mar. 31, 2024

Subsequent Events [Abstract]

Subsequent Events

10. Subsequent Events

BiBo Collaboration Agreement

On April 4, 2024, the Company entered into a collaboration agreement (the “Collaboration Agreement”) with BiBo Biopharma Engineering Co., Ltd., a company incorporated under the laws of the People’s Republic of China (“BiBo”), pursuant to which BiBo will construct a production facility specifically designed to supply the Company with pegozafermin for commercialization, if approved (the “Production Facility”).

Pursuant to the Collaboration Agreement, BiBo will build the Production Facility at BiBo’s facility in the Lin-gang Special Area of China (Shanghai) Pilot Free Trade Zone to manufacture the bulk active ingredient (the “Drug Substance”) required to produce pegozafermin for commercial supply. The platform is expected to provide the Company with manufacturing capacity to meet its commercial needs based on current projections. Under the Collaboration Agreement, the Company will pay BiBo an aggregate of $135.0 million toward the construction of the Production Facility (collectively, the “Payment”), of which 45% of the Payment will be payable in the third quarter of 2024. The remainder of the Payment will become payable upon achievement of certain specified milestones, of which up to an additional approximately 45% of the Payment could become payable within the next 12 months, depending on the timing of achievement of certain milestones. If the actual costs of the Production Facility are substantially greater than the estimated budget, the parties will negotiate a means of allocating such cost overruns.

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2024

Earnings Per Share [Abstract]

Schedule of Weighted-average Shares Outstanding Used to Calculate Basic and Diluted Net Loss Per Share

The following table presents the weighted-average shares outstanding used to calculate basic and diluted net loss per share for the periods indicated:


	Three Months Ended March 31,
	2024		2023
Common stock		93,965,659		52,371,370
Pre-funded warrants		1,881,081		800,000
Total		95,846,740		53,171,370

Schedule of Outstanding Potentially Dilutive Securities Excluded From Calculation of Diluted Net Loss


	Three Months Ended March 31,
	2024		2023
Stock options outstanding		6,891,349		4,463,459
RSUs and PSUs outstanding		1,508,546		1,218,377
Warrants to purchase common stock		10,075,092		11,688,597
Conversion feature related to outstanding term loan		590,816		590,816
ESPP		13,091		7,721
Total		19,078,894		17,968,970

Term Loan Facility

3 Months Ended

Mar. 31, 2024

Debt Disclosure [Abstract]

Term Loan Facility

6. Term Loan Facility

In January 2023, the Company entered into a Loan and Security Agreement (“the Loan Agreement”) with the lender parties thereto (the “Lenders”), K2 HealthVentures LLC as administrative agent and Ankura Trust Company, LLC as collateral agent. The Loan Agreement provides for up to $100.0 million in aggregate principal in term loans, consisting of an initial tranche of $25.0 million that was funded at closing, second and third tranches of $15.0 million and $10.0 million, respectively, that may be funded upon the achievement of certain time-based, clinical and regulatory milestones, and a fourth tranche of up to $50.0 million that may be funded upon discretionary approval by the Lenders. As of March 31, 2024, the second $15.0 million tranche expired undrawn. The third $10.0 million tranche is available through June 30, 2024 and the fourth $50.0 million tranche remains available, at the sole discretion of the Lenders.

Borrowings under the Loan Agreement are secured by substantially all of the assets of the Company, excluding the Company’s intellectual property. The Loan Agreement contains customary representations and warranties, restricts certain activities and includes customary events of default, including payment default, breach of covenants, change of control, and material adverse effects. In addition, starting January 1, 2024, the Company is required to maintain minimum unrestricted cash and cash equivalents equal to 5.0 times the average change in cash and cash equivalents measured over the trailing three-month period. As of March 31, 2024, the Company was in compliance with all covenants under the Loan Agreement.

Borrowings under the Loan Agreement mature on January 1, 2027 and provide for interest-only payments until February 1, 2025. Consecutive equal payments of principal and interest are due once the interest-only period has elapsed. Borrowings under the Loan Agreement bear interest equal to the greater of (i) 8.45% and (ii) the sum of (a) the Prime Rate as reported in The Wall Street Journal plus (b) 2.25%. The interest rate on the term loan was 9.75% at inception and 10.75% as of March 31, 2024. In addition, a final payment fee of 5.95% of the principal amount of the term loans is due upon the earlier of prepayment or maturity of the term loans. The Company has the option to prepay the entire outstanding balance of borrowings under the Loan Agreement, subject to a prepayment fee ranging from 1.0% to 3.0% depending on the timing of such prepayment. A commitment fee equal to 0.6% of the principal amount of the fourth tranche is also payable if drawn.

At any time prior to full repayment of outstanding borrowings under the Loan Agreement, the Lenders may elect to convert up to an aggregate of $7.5 million of the principal amount of outstanding borrowings into shares of the Company's common stock at a conversion price of $12.6943 per share. The embedded conversion option qualifies for a scope exception from derivative accounting because it is both indexed to the Company’s own stock and met the conditions for equity classification.

Total debt issuance costs related to the term loan facility of $0.8 million, which includes the fair value of warrants issued in connection with the facility, were recorded as debt discount. The debt discount, together with the final payment fee, are recognized as interest expense using the effective interest method over the term of the loan facility.

The expected repayments of principal amount due on borrowings as of March 31, 2024 are as follows (in thousands):


2024 (remaining nine months)	$	—
2025		10,774
2026		13,036
2027		1,190
Total principal outstanding		25,000
Plus accumulated accretion of final payment fee		493
Less unamortized debt discount		(536	)
Total net carrying value		24,957
Term loan, current		(1,892	)
Term loan, noncurrent, net	$	23,065

In connection with the Loan Agreement, the Company issued the Lenders a warrant to purchase up to an aggregate of 204,815 shares of the Company’s common stock at an exercise price of $9.7649 per share (the “warrant shares”). The warrant shares become exercisable upon the funding of each tranche and have a 10-year term. In connection with the first tranche that was funded at closing, 51,204 of the warrant shares became exercisable. The warrant shares cannot be settled for cash and include a cashless exercise feature allowing the holder to receive shares net of shares withheld in lieu of the exercise price. The warrant shares also provide for automatic cashless exercise under certain specific conditions and settlement is permitted in unregistered shares. The 51,204 warrant shares met the requirements for equity classification.

The Company determined the fair value of the 51,204 warrant shares issued using the Black-Scholes option-pricing model with the following assumptions: risk-free interest rate of 3.9%, no dividends, expected volatility of 93.8% and expected term of 10.0 years.

Of the remaining 153,611 warrant shares (the “contingent warrants”), 122,889 warrant shares remain outstanding and 30,722 warrant shares associated with the second tranche were forfeited as of March 31, 2024. The contingent warrants did not meet the derivative scope exception or equity classification criteria and were accounted for as a derivative liability. The initial fair value and the fair value as of March 31, 2024 of the contingent warrants was insignificant. The contingent warrants derivative liability is remeasured each reporting period until settled or extinguished with subsequent changes in fair value recorded as interest expense in the condensed consolidated statements of operations and comprehensive loss. The initial fair value of the contingent warrants derivative liability was determined using a probability weighted Black-Scholes option pricing model based on the same Black-Scholes input assumptions described above.

Stock-Based Compensation - Summary of Estimated Fair Value of Stock Option Awards Granted Using Black-Scholes Option-Pricing Model (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility, minimum	89.40%	91.60%
Expected volatility, maximum	90.40%	93.20%
Risk-free interest rate, minimum	3.80%	3.40%
Risk-free interest rate, maximum	4.10%	3.80%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	5 years 6 months	5 years 6 months
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (years)	6 years 1 month 6 days	6 years 1 month 6 days

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 35
-Paragraph 1D
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-URI https://asc.fasb.org//1943274/2147480483/718-10-35-1D

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section 35
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Balance Sheet Components - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued research and development expenses	$ 15,881	$ 13,017
Accrued employee and related expenses	2,603	6,248
Accrued professional and legal fees	1,776	1,110
Accrued other expenses	35	155
Total accrued expenses	$ 20,295	$ 20,530

Organization and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Date of incorporation	Jun. 30, 2019
Accumulated deficit	$ (509,113)	$ (457,432)
Cash and cash equivalents and short term available-for-sale securities	$ 562,300

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2024

Equity [Abstract]

Schedule of Shares of Common Stock Available for Future Issuance

The Company had the following shares of common stock reserved for future issuance, on an as-if-converted basis, as of the periods presented:


	March 31, 2024		December 31, 2023
Stock options outstanding		6,891,349		4,686,577
RSUs and PSUs outstanding		1,508,546		987,550
Shares available for future grants under equity incentive plans		2,600,491		1,790,684
Shares available for future issuance under the employee stock purchase plan		1,207,607		1,207,607
Warrants to purchase common stock outstanding		10,075,092		10,412,806
Pre-funded warrants to purchase common stock outstanding		1,881,081		1,881,081
Conversion feature related to outstanding term loan		590,816		590,816
Total available for future issuance		24,754,982		21,557,121

Schedule of Outstanding Warrants to Purchase Shares of Common Stock

As of March 31, 2024, the Company’s outstanding warrants to purchase shares of its common stock were as follows:


	Shares of Common Stock Underlying Warrants		Exercise Price Per Share		Expiration Date
Warrant issued in connection with term loan (SVB)		25,000	$	22.06	June 30, 2025
Warrant issued in connection with term loan (SVB)		33,923		19.12	May 28, 2031
Warrants issued in connection with term loan facility		174,093		9.76	January 27, 2033
Warrants issued in connection with public offering		9,842,076		5.325	July 1, 2024
Pre-funded warrants issued in connection with public offerings		1,881,081		0.001	Do not expire
Total outstanding		11,956,173

Stockholders' Equity

3 Months Ended

Mar. 31, 2024

Equity [Abstract]

Stockholders' Equity

7. Stockholders’ Equity

Common Stock Reserved for Issuance

The Company had the following shares of common stock reserved for future issuance, on an as-if-converted basis, as of the periods presented:


	March 31, 2024		December 31, 2023
Stock options outstanding		6,891,349		4,686,577
RSUs and PSUs outstanding		1,508,546		987,550
Shares available for future grants under equity incentive plans		2,600,491		1,790,684
Shares available for future issuance under the employee stock purchase plan		1,207,607		1,207,607
Warrants to purchase common stock outstanding		10,075,092		10,412,806
Pre-funded warrants to purchase common stock outstanding		1,881,081		1,881,081
Conversion feature related to outstanding term loan		590,816		590,816
Total available for future issuance		24,754,982		21,557,121

At-the-Market (“ATM”) Offerings

In March 2021, the Company entered into an ATM sales agreement (as amended, the “Sales Agreement”) with Leerink Partners LLC and Cantor Fitzgerald & Co. (the “Sales Agents”) pursuant to which the Company may offer and sell shares up to $75.0 million of its common stock (the “2021 ATM Facility”) from time to time pursuant to an effective registration statement. The Sales Agents are entitled to compensation at a commission of up to 3.0% of the aggregate gross sales price per share sold under the Sales Agreement. For the three months ended March 31, 2023, the Company sold 968,000 shares of its common stock under the 2021 ATM Facility and received net proceeds of $13.4 million, after deducting commissions and offering costs of $0.4 million.

In February 2023, the Company entered into an amendment to the Sales Agreement, establishing a new ATM facility with an aggregate offering amount of up to $150.0 million of its common stock (the “2023 ATM Facility”) pursuant to an effective registration statement. For the three months ended March 31, 2024, the Company sold 1,396,888 shares of its common stock under the 2023 ATM Facility resulting in net proceeds of $21.0 million, after deducting commissions and offering costs of $0.5 million. As of March 31, 2024, there was $104.4 million remaining for future sales under the 2023 ATM Facility.

Underwritten Public Offerings

In March 2023, the Company completed an underwritten public offering of its common stock. The Company sold 19,461,538 shares of its common stock at a public offering price of $16.25 per share and received net proceeds of $296.8 million, net of underwriting discounts and commissions of $19.0 million and other offering costs of $0.5 million.

Common Stock Warrants

As of March 31, 2024, the Company’s outstanding warrants to purchase shares of its common stock were as follows:


	Shares of Common Stock Underlying Warrants		Exercise Price Per Share		Expiration Date
Warrant issued in connection with term loan (SVB)		25,000	$	22.06	June 30, 2025
Warrant issued in connection with term loan (SVB)		33,923		19.12	May 28, 2031
Warrants issued in connection with term loan facility		174,093		9.76	January 27, 2033
Warrants issued in connection with public offering		9,842,076		5.325	July 1, 2024
Pre-funded warrants issued in connection with public offerings		1,881,081		0.001	Do not expire
Total outstanding		11,956,173

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-URI https://asc.fasb.org//505/tableOfContent

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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Net Loss Per Share - Schedule of Outstanding Potentially Dilutive Securities Excluded From Calculation of Diluted Net Loss (Details) - shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	19,078,894	17,968,970
Stock Options Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	6,891,349	4,463,459
RSUs and PSUs Outstanding
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	1,508,546	1,218,377
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	10,075,092	11,688,597
Conversion Feature Related To Outstanding Term Loan
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	590,816	590,816
ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive common stock equivalents excluded from calculation of diluted net loss per share	13,091	7,721

Stockholders' Equity - Schedule of Shares of Common Stock Available for Future Issuance (Details) - shares	Mar. 31, 2024	Dec. 31, 2023
Class Of Stock [Line Items]
Total available for future issuance	24,754,982	21,557,121
Stock Options Outstanding
Class Of Stock [Line Items]
Total available for future issuance	6,891,349	4,686,577
Rsus And Psus Outstanding
Class Of Stock [Line Items]
Total available for future issuance	1,508,546	987,550
Equity Incentive Plan
Class Of Stock [Line Items]
Total available for future issuance	2,600,491	1,790,684
Employee Stock Purchase Plan
Class Of Stock [Line Items]
Total available for future issuance	1,207,607	1,207,607
Warrants To Purchase Common Stock
Class Of Stock [Line Items]
Total available for future issuance	10,075,092	10,412,806
Pre-funded Warrants To Purchase Common Stock
Class Of Stock [Line Items]
Total available for future issuance	1,881,081	1,881,081
Conversion Feature Related To Outstanding Term Loan
Class Of Stock [Line Items]
Total available for future issuance	590,816	590,816

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 272
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-Name Accounting Standards Codification
-Section 45
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483014/272-10-45-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 272
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-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482987/272-10-50-1

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(d))
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-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
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-Paragraph 13
-Subparagraph (h)
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-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(27)(b))
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-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(28))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(29))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Paragraph 3
-Subparagraph (SX 210.6-03(i)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479886/946-10-S99-3

+ Details

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

The accompanying interim unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”), the instructions to Form 10-Q and Rule 10-01 of Regulation S-X and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting.

Unaudited Interim Condensed Consolidated Financial Statements

The accompanying interim condensed consolidated financial statements are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements as of and for the year ended December 31, 2023 and reflect all normal recurring adjustments that are necessary to present fairly the results for the interim periods presented. Interim results are not necessarily indicative of the results to be expected for the full year ending December 31, 2024 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2023 was derived from the audited financial statements as of that date and, due to its summary nature, does not include all the disclosures required by U.S. GAAP in audited financial statements. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements included in the Annual Report on Form 10-K for the year ended December 31, 2023, which was filed with the SEC on March 1, 2024.

Principles of Consolidation

The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. For the Company and its subsidiary in Israel, the functional currency has been determined to be the U.S. Dollar.

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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements include but are not limited to accruals for uncertain tax positions, accrued research and development expenses and the valuation of stock options. The

Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.

Fair Value Measurements

Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. Assets and liabilities recorded at fair value are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels are directly related to the amount of subjectivity with the inputs to the valuation of these assets or liabilities 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 inputs for similar assets or liabilities. These include quoted prices for identical or similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; and

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 Measured at Fair Value on a Recurring Basis

As of March 31, 2024 and December 31, 2023, cash equivalents and marketable securities were the only financial instruments measured and recorded at fair value on a recurring basis on the Company’s condensed consolidated balance sheets.

Financial Instruments Not Carried at Fair Value

The Company’s financial instruments, including cash, other current assets, accounts payable and accrued expenses are carried at cost which approximates their fair value because of the short-term nature of these financial instruments. The fair value of the Company’s term loan approximates its carrying value, or amortized cost, due to the prevailing market rates of interest it bears.

Cash and Cash Equivalents

The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents primarily consist of amounts invested in money market funds, commercial paper and U.S. government Treasury securities and are carried at fair value.

Marketable Securities

The Company invests its excess cash in marketable securities with high credit ratings including money market funds, commercial paper, securities issued by the U.S. government and its agencies and corporate debt securities. The Company accounts for all marketable securities as available-for-sale, as the sale of such securities may be required prior to maturity. These marketable securities are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The cost of debt securities is adjusted for accretion of premiums and amortization of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income and other, net. Realized gains and losses from the sale of marketable securities, if any, are determined on a specific identification basis and are also included in interest income and other, net. The Company’s marketable securities are classified as current assets, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary, even though the stated maturity date may be one year or more beyond the current balance sheet date.

The Company periodically assesses its marketable securities for impairment. For marketable securities in an unrealized loss position, this assessment first takes into account the Company’s intent to sell, or whether it is more likely than not that it will be required to sell the security before recovery of its amortized cost basis. If either of these criteria are met, the marketable security’s amortized cost basis is written down to fair value through interest income and other, net. For marketable securities in an unrealized loss position that do not meet the aforementioned criteria, the Company assesses whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss may exist, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses will be recorded in interest income and other, net, limited by the amount that the fair value is less than the amortized cost basis. Any additional impairment not recorded through an allowance for credit losses is recognized in other comprehensive loss. Changes in the allowance for credit losses are recorded as provision for (or reversal of) credit loss expense. Losses are charged against the allowance when management believes the uncollectability of a security is confirmed or when either of the criteria regarding intent or requirement to sell is met. These changes are recorded in interest income and other, net.

Income Taxes

The Company accounts for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. Interest and penalties related to unrecognized tax benefits are included within income tax expense. For the three months ended March 31, 2024, the Company recorded income tax expense of $0.1 million for the accrual of additional interest related to unrecognized tax benefits.

Basic and Diluted Net Loss per Share

Basic and diluted net loss per share is calculated based upon the weighted-average number of shares of common stock outstanding during the period. Shares of common stock that are potentially issuable for little or no cash consideration at issuance, such as the Company’s pre-funded warrants issued in July 2022 and December 2023 are included in the calculation of basic and diluted net loss per share, even if they are antidilutive. During periods of income, participating securities are allocated a proportional share of income determined by dividing total weighted-average participating securities by the sum of the total weighted-average common shares and participating securities (the “two-class method”). Shares of the Company’s common stock warrants participate in any dividends that may be declared by the Company and are therefore considered to be participating securities. Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods of loss, no loss is allocated to participating securities since they have no contractual obligation to share in the losses of the Company. Diluted loss per share is computed after giving consideration to the dilutive effect of stock options, restricted stock units (“RSUs”), performance stock units (“PSUs”) and common stock warrants, except where such non-participating securities would be anti-dilutive. As the Company incurred net losses for the periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive.

Recently Adopted Accounting Standards

The Company did not adopt any new standards or updates issued by the Financial Accounting Standards Board (“FASB”) during the three months ended March 31, 2024 that had a material impact on the Company’s consolidated financial statements and related disclosures.

Accounting Pronouncements Not Yet Adopted

In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which is intended to improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant expenses. ASU 2023-07 requires disclosures to include significant segment expenses that are regularly provided to the chief operating decision maker (“CODM”), a description of other segment items by reportable segment, and any additional measures of a segment’s profit or loss used by the CODM when deciding how to allocate resources. The ASU also requires all annual disclosures required by Topic 280 to be included in interim periods. All disclosure requirements under this ASU are also required for public entities with a single reportable segment. The ASU is effective for the Company’s annual periods beginning on January 1, 2024 and interim periods beginning on January 1, 2025. Early adoption is permitted and requires retrospective application to all prior periods presented in the financial statements. The Company expects to adopt ASU 2023-07 in its Annual Report on Form 10-K for the year ending December 31, 2024 and in the interim periods thereafter. The Company is in the process of evaluating the requirements of this update, which is expected to result in expanded disclosures within the consolidated financial statements upon adoption.

In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which requires companies to disclose, on an annual basis, specific categories in the effective tax rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. In addition, ASU 2023-09 requires companies to disclose additional information about income taxes paid. The ASU is effective for the Company’s annual periods beginning on January 1, 2025 and will be applied on a prospective basis with the option to apply the standard retrospectively. Early adoption is permitted. The Company expects to adopt ASU 2023-09 in its Annual Report on Form 10-K for the year ending December 31, 2025 and in annual periods thereafter. The Company is in the process of evaluating the requirements of this update, which is expected to result in expanded disclosures within the consolidated financial statements upon adoption.

Commitments and Contingencies

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

5. Commitments and Contingencies

Asset Transfer and License Agreement with Teva Pharmaceutical Industries Ltd

In April 2018, the Company concurrently entered into two Asset Transfer and License Agreements (the “Teva Agreements”) with Teva Pharmaceutical Industries Ltd (“Teva”) under which it acquired certain patents and intellectual property relating to two programs: (1) Teva’s glycoPEGylated FGF21 program, including the compound TEV-47948 (pegozafermin), a glycoPEGylated long-acting FGF21 and (2) Teva’s development program of small molecule inhibitors of Fatty Acid Synthase. Pursuant to the Teva Agreements, the Company paid Teva an initial nonrefundable upfront payment of $6.0 million. Under each license agreement, the Company is required to pay Teva $2.5 million upon the achievement of a specified clinical development milestone, and additional payments totaling up to $65.0 million upon achievement of certain commercial milestones. Each milestone payment shall be payable once, upon the first occurrence of the applicable milestone. The Company is also obligated to pay Teva tiered royalties at percentages in the low-to-mid single-digits on worldwide net sales on all products containing the Teva compounds.

The Teva Agreements can be terminated (i) by the Company without cause upon 120 days’ written notice to Teva, (ii) by either party, if the other party materially breaches any of its obligations under the Teva Agreements and fails to cure such breach within 60 days after receiving notice thereof, or (iii) by either party, if a bankruptcy petition is filed against the other party and is not dismissed within 60 days. In addition, Teva can also terminate the agreement related to their glycoPEGylated FGF21 program in the event the Company, or any of its affiliates or sublicensees, challenges any of the Teva patents licensed to the Company, and the challenge is not withdrawn within 30 days of written notice from Teva.

In the fourth quarter of 2023, the Company made a $2.5 million milestone payment to Teva following the achievement of a clinical development milestone under the FGF21 program in SHTG. As of March 31, 2024, the timing and likelihood of achieving any remaining milestones are uncertain. Milestone payment obligations will be recognized when payment becomes probable and reasonably estimable, which is generally upon achievement of the applicable milestone.

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities:
Net loss	$ (51,681)	$ (28,836)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	4,998	3,551
Net accretion of discounts on investments in marketable securities	(2,822)	(1,040)
Amortization of debt discount and accretion of deferred debt costs	162	219
Loss on extinguishment of debt		1,208
Noncash operating lease expense	175	41
Depreciation	9	14
Changes in operating assets and liabilities:
Prepaid and other assets	2,089	(4,599)
Accounts payable	6,767	4,225
Accrued expenses	457	(4,827)
Operating lease liabilities	29	(41)
Other noncurrent liabilities	97
Net cash used in operating activities	(39,720)	(30,085)
Cash flows from investing activities:
Proceeds from sales and maturities of marketable securities	72,140	37,880
Purchases of marketable securities	(152,038)	(33,774)
Net cash (used in) provided by investing activities	(79,898)	4,106
Cash flows from financing activities:
Proceeds from issuance of common stock in public offerings, net of issuance costs		296,817
Payments of deferred offering costs	(253)
Proceeds from issuance of common stock in at-the-market public offerings, net of issuance costs	21,067	13,422
Proceeds from term loan facility, net of issuance costs		24,363
Proceeds from issuance of common stock upon exercise of common stock warrants	1,798	8,960
Proceeds from issuance of common stock upon exercise of stock options	104	185
Payments for taxes related to net share settlement upon vesting of restricted stock units	(1,686)	(693)
Repayment of term loan		(21,400)
Net cash provided by financing activities	21,030	321,654
Net change in cash and cash equivalents	(98,588)	295,675
Cash and cash equivalents at beginning of period	316,161	55,255
Cash and cash equivalents at end of period	217,573	350,930
Supplemental disclosures of cash information:
Cash paid for interest	679	542
Cash paid related to operating lease liabilities	46	47
Supplemental disclosures of noncash information:
Issuance of common stock warrants in connection with term loan		$ 482
Unpaid offering costs included in accrued expenses	$ 18

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Aggregated Fair Value	$ 429,846
Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	430,374	$ 361,117
Short-term investments, Gross Unrealized Holding Gains	57	439
Short-term investments, Gross Unrealized Holding Losses	(585)	(254)
Short-term investments, Aggregated Fair Value	429,846	361,302
Total cash equivalents and marketable securities	429,846	361,302
Recurring \| Marketable securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Aggregated Fair Value	344,715	262,709
Recurring \| Cash equivalents
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Aggregated Fair Value	85,131	98,593
Recurring \| Level 1 \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	4,073	493
Short-term investments, Aggregated Fair Value	4,073	493
Recurring \| Level 2 \| Commercial Paper
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	124,016	94,261
Short-term investments, Gross Unrealized Holding Losses	(71)	(55)
Short-term investments, Aggregated Fair Value	123,945	94,206
Recurring \| Level 2 \| U.S. government bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	194,344	137,976
Short-term investments, Gross Unrealized Holding Gains	47	250
Short-term investments, Gross Unrealized Holding Losses	(377)	(142)
Short-term investments, Aggregated Fair Value	194,014	138,084
Recurring \| Level 2 \| Agency bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	53,252	45,481
Short-term investments, Gross Unrealized Holding Gains	10	152
Short-term investments, Gross Unrealized Holding Losses	(107)	(44)
Short-term investments, Aggregated Fair Value	53,155	45,589
Recurring \| Level 2 \| Corporate debt securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	5,184	3,177
Short-term investments, Gross Unrealized Holding Losses	(22)	(12)
Short-term investments, Aggregated Fair Value	5,162	3,165
Recurring \| Level 2 \| U.S. Treasury securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost	49,505	71,754
Short-term investments, Gross Unrealized Holding Gains	0	36
Short-term investments, Gross Unrealized Holding Losses	(8)	(1)
Short-term investments, Aggregated Fair Value	$ 49,497	71,789
Recurring \| Level 2 \| Agency discount securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term investments, Amortized Cost		7,975
Short-term investments, Gross Unrealized Holding Gains		1
Short-term investments, Aggregated Fair Value		$ 7,976

Fair Value Measurements - Schedule of Contractual Maturities of Financial Assets Measured at Fair Value (Details) $ in Thousands	Mar. 31, 2024 USD ($)
Fair Value Disclosures [Abstract]
Within one year	$ 314,373
After one year through two years	115,473
Total cash equivalents and marketable securities	$ 429,846

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for future issuance	24,754,982		21,557,121
Share base compensation expense	$ 4,998	$ 3,551
Performance Stock Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized weighted average period	1 year 10 months 24 days
Total Unrecognised expense	$ 12,300
Employee Stock Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized weighted average period	3 years
Unrecognized unvested stock option	$ 34,800
Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares reserved for future issuance	1,207,607		1,207,607
Minimum \| Restricted Stock Units (RSUs")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	2 years
Minimum \| Performance Stock Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	1 year
Maximum \| Restricted Stock Units (RSUs")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Maximum \| Performance Stock Units (PSUs)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years

Stock-Based Compensation - Summary of Restricted Stock Unit Activity (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Restricted Stock Units (RSUs")
Number of RSUs
Outstanding, Beginning Balance \| shares	688,382
Granted \| shares	651,950
Vested / released \| shares	(157,172)
Cancelled / forfeited \| shares	(6,614)
Outstanding, Ending Balance \| shares	1,176,546
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value Outstanding, Beginning Balance \| $ / shares	$ 10.72
Weighted Average Grant Date Fair Value Outstanding, Granted \| $ / shares	9.98
Weighted Average Grant Date Fair Value Outstanding, Vested/Released \| $ / shares	13.43
Weighted Average Grant Date Fair Value Outstanding, Cancelled/Forfeited \| $ / shares	10.78
Weighted Average Grant Date Fair Value Outstanding, Ending Balance \| $ / shares	$ 9.95
Performance Shares (PSUs)
Number of RSUs
Outstanding, Beginning Balance \| shares	299,168
Granted \| shares	192,000
Vested / released \| shares	(159,168)
Outstanding, Ending Balance \| shares	332,000
Weighted Average Grant Date Fair Value
Weighted Average Grant Date Fair Value Outstanding, Beginning Balance \| $ / shares	$ 5.96
Weighted Average Grant Date Fair Value Outstanding, Granted \| $ / shares	9.98
Weighted Average Grant Date Fair Value Outstanding, Vested/Released \| $ / shares	7
Weighted Average Grant Date Fair Value Outstanding, Ending Balance \| $ / shares	$ 7.79

Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	ATM Facility	Common Stock	Common Stock Public Offerings	Common Stock ATM Facility	Additional Paid-in Capital	Additional Paid-in Capital Public Offerings	Additional Paid-in Capital ATM Facility	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance at Dec. 31, 2022	$ 151,832		$ 51			$ 467,374			$ (350)	$ (315,243)
Beginning balance, shares at Dec. 31, 2022			50,560,590
Issuance of common stock	296,817	$ 13,422		$ 19	$ 1		$ 296,798	$ 13,421
Issuance of common stock, shares				19,461,538	968,000
Issuance of common stock upon exercise of common stock warrants	8,960		$ 2			8,958
Issuance of common stock upon exercise of common stock warrants, shares			1,682,500
Issuance of common stock upon exercise of stock options	185					185
Issuance of common stock upon exercise of stock options, shares			61,408
Issuance of common stock upon vesting of restricted stock units, net of withholding taxes	(693)					(693)
Issuance of common stock upon vesting of restricted stock units, net of withholding taxes, shares			133,669
Issuance of common stock warrants in connection with term loan	482					482
Stock-based compensation	3,551					3,551
Net loss	(28,836)									(28,836)
Other comprehensive income (loss)	110								110
Ending balance at Mar. 31, 2023	445,830		$ 73			790,076			(240)	(344,079)
Ending balance, shares at Mar. 31, 2023			72,867,705
Beginning balance at Dec. 31, 2023	536,306		$ 93			993,455			190	(457,432)
Beginning balance, shares at Dec. 31, 2023			93,269,377
Issuance of common stock		$ 21,049			$ 2			$ 21,047
Issuance of common stock, shares					1,396,888
Issuance of common stock upon exercise of common stock warrants	1,798					1,798
Issuance of common stock upon exercise of common stock warrants, shares			337,713
Issuance of common stock upon exercise of stock options	7					7
Issuance of common stock upon exercise of stock options, shares			1,626
Issuance of common stock upon vesting of restricted stock units, net of tax withholding for net share settlement	(1,229)					(1,229)
Issuance of common stock upon vesting of restricted stock units, net of tax withholding for net share settlement, shares			194,120
Stock-based compensation	4,998					4,998
Net loss	(51,681)									(51,681)
Other comprehensive income (loss)	(709)								(709)
Ending balance at Mar. 31, 2024	$ 510,539		$ 95			$ 1,020,076			$ (519)	$ (509,113)
Ending balance, shares at Mar. 31, 2024			95,199,724

Term Loan Facility - Additional Information (Details) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended
	Jan. 01, 2027	Jan. 31, 2023 USD ($) $ / shares shares	Mar. 31, 2024 USD ($) shares	Mar. 31, 2023 USD ($)
Debt Instrument [Line Items]
Debt discount			$ 536
Loss on extinguishment				$ (1,208)
Tranche One
Debt Instrument [Line Items]
Warrants to purchase common stock \| shares		51,204
2023 Loan Agreement
Debt Instrument [Line Items]
Warrant exercise price \| $ / shares		$ 9.7649
Minimum unrestriced cash and cash equivalents to three month average cash and cash equivalents multiplier			5
Debt instrument, maturity date			Jan. 01, 2027
Debt instrument, maturity date, description			Borrowings under the Loan Agreement mature on January 1, 2027 and provide for interest-only payments until February 1, 2025.
Debt instrument, interest rate		9.75%	10.75%
Debt instrument, basis spread on variable rate		2.25%
Conversion price per share \| $ / shares		$ 12.6943
Contingent warrants \| shares		153,611
Warrant Forfeited \| shares			30,722
2023 Loan Agreement \| Forecast
Debt Instrument [Line Items]
Percentage of fee on loan	5.95%
2023 Loan Agreement \| Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate		8.45%
Prepayment fee percentage			3.00%
2023 Loan Agreement \| Maximum
Debt Instrument [Line Items]
Debt Instrument face amount		$ 100,000
Warrants to purchase common stock \| shares		204,815
Prepayment fee percentage			1.00%
Conversion of principal amount		$ 7,500
2023 Loan Agreement \| Tranche One
Debt Instrument [Line Items]
Debt discount		800
Line of credit facility fully drawn amount		25,000
2023 Loan Agreement \| Tranche One \| Measurement Input, Expected Dividend Payment
Debt Instrument [Line Items]
Fair value of warrant assumptions, dividends		$ 0
2023 Loan Agreement \| Tranche One \| Valuation Technique, Option Pricing Model \| Measurement Input, Risk Free Interest Rate
Debt Instrument [Line Items]
Fair measurement input		0.039
2023 Loan Agreement \| Tranche One \| Valuation Technique, Option Pricing Model \| Measurement Input, Price Volatility
Debt Instrument [Line Items]
Fair measurement input		0.938
2023 Loan Agreement \| Tranche One \| Valuation Technique, Option Pricing Model \| Measurement Input, Expected Term
Debt Instrument [Line Items]
Fair measurement input		10 years
2023 Loan Agreement \| Tranche Two
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 15,000
Warrant contingently exercisable upon funding of each subsequent term loan \| shares			122,889
2023 Loan Agreement \| Tranche Three
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		10,000
2023 Loan Agreement \| Tranche Four
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 50,000
Commitment fee percentage			0.60%
2024 Loan Agreement \| Tranche Two
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 15,000
2024 Loan Agreement \| Tranche Three
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			10,000
2024 Loan Agreement \| Tranche Four
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 50,000

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2024
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying interim unaudited condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States (“U.S. GAAP”), the instructions to Form 10-Q and Rule 10-01 of Regulation S-X and applicable rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting.
Unaudited Interim Condensed Consolidated Financial Statements	Unaudited Interim Condensed Consolidated Financial Statements The accompanying interim condensed consolidated financial statements are unaudited. The interim unaudited condensed consolidated financial statements have been prepared on the same basis as the audited consolidated financial statements as of and for the year ended December 31, 2023 and reflect all normal recurring adjustments that are necessary to present fairly the results for the interim periods presented. Interim results are not necessarily indicative of the results to be expected for the full year ending December 31, 2024 or for any other future annual or interim period. The condensed consolidated balance sheet as of December 31, 2023 was derived from the audited financial statements as of that date and, due to its summary nature, does not include all the disclosures required by U.S. GAAP in audited financial statements. These condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements included in the Annual Report on Form 10-K for the year ended December 31, 2023, which was filed with the SEC on March 1, 2024.
Principles of Consolidation	Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. For the Company and its subsidiary in Israel, the functional currency has been determined to be the U.S. Dollar.
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 reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the condensed consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions made in the accompanying condensed consolidated financial statements include but are not limited to accruals for uncertain tax positions, accrued research and development expenses and the valuation of stock options. The Company evaluates its estimates and assumptions on an ongoing basis using historical experience and other factors and adjusts those estimates and assumptions when facts and circumstances dictate. Actual results could differ from those estimates.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. Assets and liabilities recorded at fair value are categorized based upon the level of judgment associated with the inputs used to measure their fair value. Hierarchical levels are directly related to the amount of subjectivity with the inputs to the valuation of these assets or liabilities 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 inputs for similar assets or liabilities. These include quoted prices for identical or similar assets or liabilities in active markets and quoted prices for identical or similar assets or liabilities in markets that are not active; and 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 Measured at Fair Value on a Recurring Basis As of March 31, 2024 and December 31, 2023, cash equivalents and marketable securities were the only financial instruments measured and recorded at fair value on a recurring basis on the Company’s condensed consolidated balance sheets. Financial Instruments Not Carried at Fair Value The Company’s financial instruments, including cash, other current assets, accounts payable and accrued expenses are carried at cost which approximates their fair value because of the short-term nature of these financial instruments. The fair value of the Company’s term loan approximates its carrying value, or amortized cost, due to the prevailing market rates of interest it bears.
Cash and Cash Equivalents	Cash and Cash Equivalents The Company considers all highly liquid investments purchased with original maturities of three months or less from the purchase date to be cash equivalents. Cash equivalents primarily consist of amounts invested in money market funds, commercial paper and U.S. government Treasury securities and are carried at fair value.
Marketable Securities	Marketable Securities The Company invests its excess cash in marketable securities with high credit ratings including money market funds, commercial paper, securities issued by the U.S. government and its agencies and corporate debt securities. The Company accounts for all marketable securities as available-for-sale, as the sale of such securities may be required prior to maturity. These marketable securities are carried at fair value, with unrealized gains and losses reported as accumulated other comprehensive income (loss) until realized. The cost of debt securities is adjusted for accretion of premiums and amortization of discounts to maturity. Such amortization and accretion, as well as interest and dividends, are included in interest income and other, net. Realized gains and losses from the sale of marketable securities, if any, are determined on a specific identification basis and are also included in interest income and other, net. The Company’s marketable securities are classified as current assets, which reflects management’s intention to use the proceeds from sales of these securities to fund its operations, as necessary, even though the stated maturity date may be one year or more beyond the current balance sheet date. The Company periodically assesses its marketable securities for impairment. For marketable securities in an unrealized loss position, this assessment first takes into account the Company’s intent to sell, or whether it is more likely than not that it will be required to sell the security before recovery of its amortized cost basis. If either of these criteria are met, the marketable security’s amortized cost basis is written down to fair value through interest income and other, net. For marketable securities in an unrealized loss position that do not meet the aforementioned criteria, the Company assesses whether the decline in fair value has resulted from credit losses or other factors. In making this assessment, the Company considers the extent to which fair value is less than amortized cost, any changes to the rating of the security by a rating agency, and any adverse conditions specifically related to the security, among other factors. If this assessment indicates that a credit loss may exist, the present value of cash flows expected to be collected from the security are compared to the amortized cost basis of the security. If the present value of cash flows expected to be collected is less than the amortized cost basis, a credit loss exists and an allowance for credit losses will be recorded in interest income and other, net, limited by the amount that the fair value is less than the amortized cost basis. Any additional impairment not recorded through an allowance for credit losses is recognized in other comprehensive loss. Changes in the allowance for credit losses are recorded as provision for (or reversal of) credit loss expense. Losses are charged against the allowance when management believes the uncollectability of a security is confirmed or when either of the criteria regarding intent or requirement to sell is met. These changes are recorded in interest income and other, net.
Income Taxes	Income Taxes The Company accounts for uncertain tax positions using a more-likely-than-not threshold for recognizing and resolving uncertain tax positions. This evaluation is based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, effectively settled issues under audit, and new audit activity. Interest and penalties related to unrecognized tax benefits are included within income tax expense. For the three months ended March 31, 2024, the Company recorded income tax expense of $0.1 million for the accrual of additional interest related to unrecognized tax benefits.
Basic and Diluted Net Loss per Share	Basic and Diluted Net Loss per Share Basic and diluted net loss per share is calculated based upon the weighted-average number of shares of common stock outstanding during the period. Shares of common stock that are potentially issuable for little or no cash consideration at issuance, such as the Company’s pre-funded warrants issued in July 2022 and December 2023 are included in the calculation of basic and diluted net loss per share, even if they are antidilutive. During periods of income, participating securities are allocated a proportional share of income determined by dividing total weighted-average participating securities by the sum of the total weighted-average common shares and participating securities (the “two-class method”). Shares of the Company’s common stock warrants participate in any dividends that may be declared by the Company and are therefore considered to be participating securities. Participating securities have the effect of diluting both basic and diluted earnings per share during periods of income. During periods of loss, no loss is allocated to participating securities since they have no contractual obligation to share in the losses of the Company. Diluted loss per share is computed after giving consideration to the dilutive effect of stock options, restricted stock units (“RSUs”), performance stock units (“PSUs”) and common stock warrants, except where such non-participating securities would be anti-dilutive. As the Company incurred net losses for the periods presented, basic net loss per share is the same as diluted net loss per share since the effects of potentially dilutive securities are antidilutive.
Recent Adopted And Accounting Pronouncements	Recently Adopted Accounting Standards The Company did not adopt any new standards or updates issued by the Financial Accounting Standards Board (“FASB”) during the three months ended March 31, 2024 that had a material impact on the Company’s consolidated financial statements and related disclosures. Accounting Pronouncements Not Yet Adopted In November 2023, the FASB issued ASU No. 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures (“ASU 2023-07”), which is intended to improve reportable segment disclosure requirements, primarily through enhanced disclosures about significant expenses. ASU 2023-07 requires disclosures to include significant segment expenses that are regularly provided to the chief operating decision maker (“CODM”), a description of other segment items by reportable segment, and any additional measures of a segment’s profit or loss used by the CODM when deciding how to allocate resources. The ASU also requires all annual disclosures required by Topic 280 to be included in interim periods. All disclosure requirements under this ASU are also required for public entities with a single reportable segment. The ASU is effective for the Company’s annual periods beginning on January 1, 2024 and interim periods beginning on January 1, 2025. Early adoption is permitted and requires retrospective application to all prior periods presented in the financial statements. The Company expects to adopt ASU 2023-07 in its Annual Report on Form 10-K for the year ending December 31, 2024 and in the interim periods thereafter. The Company is in the process of evaluating the requirements of this update, which is expected to result in expanded disclosures within the consolidated financial statements upon adoption. In December 2023, the FASB issued ASU No. 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures (“ASU 2023-09”), which requires companies to disclose, on an annual basis, specific categories in the effective tax rate reconciliation and provide additional information for reconciling items that meet a quantitative threshold. In addition, ASU 2023-09 requires companies to disclose additional information about income taxes paid. The ASU is effective for the Company’s annual periods beginning on January 1, 2025 and will be applied on a prospective basis with the option to apply the standard retrospectively. Early adoption is permitted. The Company expects to adopt ASU 2023-09 in its Annual Report on Form 10-K for the year ending December 31, 2025 and in annual periods thereafter. The Company is in the process of evaluating the requirements of this update, which is expected to result in expanded disclosures within the consolidated financial statements upon adoption.

Subsequent Events - Additional Information (Details) - Subsequent Events - Collaboration Agreement $ in Millions	Apr. 04, 2024 USD ($)
Subsequent Event [Line Items]
Agreement date	Apr. 04, 2024
BiBo Biopharma Engineering Co., Ltd.
Subsequent Event [Line Items]
Aggregate payment of production facility	$ 135.0
Percentage of production facility payment payable	45.00%
Additional percentage of milestones payment payable upon achievement	45.00%

Balance Sheet Components

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components

4. Balance Sheet Components

Prepaid and other current assets consist of the following as of the periods presented (in thousands):


	March 31, 2024		December 31, 2023
Prepaid research and development	$	9,009	$	11,579
Prepaid taxes		615		614
Prepaid other		2,870		2,471
Total prepaid and other current assets	$	12,494	$	14,664

Accrued expenses consist of the following as of the periods presented (in thousands):


	March 31, 2024		December 31, 2023
Accrued research and development expenses	$	15,881	$	13,017
Accrued employee and related expenses		2,603		6,248
Accrued professional and legal fees		1,776		1,110
Accrued other expenses		35		155
Total accrued expenses	$	20,295	$	20,530

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Summary Of Significant Accounting Policies [Line Items]
Income tax expense	$ 97	$ 0

- Definition

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

+ References + Details

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 06, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Entity Registrant Name	89bio, Inc.
Entity Central Index Key	0001785173
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		98,383,998
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false
Title of 12(b) Security	Common stock, par value $0.001 per share
Trading Symbol	ETNB
Security Exchange Name	NASDAQ
Entity File Number	001-39122
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	36-4946844
Entity Address, Address Line One	142 Sansome Street
Entity Address, Address Line Two	Second Floor
Entity Address, City or Town	San Francisco
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94104
City Area Code	415
Local Phone Number	432-9270
Document Quarterly Report	true
Document Transition Report	false

Stockholders' Equity - Schedule of Outstanding Warrants to Purchase Shares of Common Stock (Details)	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	11,956,173
Warrants Term Loan
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	25,000
Warrant exercise price \| $ / shares	$ 22.06
Warrant expiration date	Jun. 30, 2025
Warrants Term Loan
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	33,923
Warrant exercise price \| $ / shares	$ 19.12
Warrant expiration date	May 28, 2031
Warrants Term Loan
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	174,093
Warrant exercise price \| $ / shares	$ 9.76
Warrant expiration date	Jan. 27, 2033
Warrants Public Offerings
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	9,842,076
Warrant exercise price \| $ / shares	$ 5.325
Warrant expiration date	Jul. 01, 2024
Pre-funded Warrants
Class Of Warrant Or Right [Line Items]
Shares of Common Stock Underlying Warrants	1,881,081
Warrant exercise price \| $ / shares	$ 0.001
Expiration Date	Do not expire

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 217,573	$ 316,161
Marketable securities	344,715	262,709
Prepaid and other current assets	12,494	14,664
Total current assets	574,782	593,534
Operating lease right-of-use assets	2,118	2,293
Property and equipment, net	37	46
Other assets	385	396
Total assets	577,322	596,269
Current liabilities:
Accounts payable	15,352	8,585
Accrued expenses	20,295	20,530
Operating lease liabilities, current	702	496
Term loan, current	1,892	0
Total current liabilities	38,241	29,611
Operating lease liability, non-current	1,640	1,817
Term loan, noncurrent, net	23,065	24,795
Other noncurrent liabilities	3,837	3,740
Total liabilities	66,783	59,963
Commitments and contingencies (Note 5)
Stockholders’ equity:
Common stock, $0.001 par value: 200,000,000 shares authorized; 95,199,724 and 93,269,377 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively	95	93
Additional paid-in capital	1,020,076	993,455
Accumulated other comprehensive (loss) income	(519)	190
Accumulated deficit	(509,113)	(457,432)
Total stockholders’ equity	510,539	536,306
Total liabilities and stockholders’ equity	$ 577,322	$ 596,269