0001564590-22-019269 | 10-Q | XBRL Viewer

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Stock-Based Compensation - Summary of Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 2,660	$ 2,744
Research And Development Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	1,004	1,081
General And Administrative Expense
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 1,656	$ 1,663

Marketable Securities (Tables)

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

Summary of Marketable Securities Classified as Available-for-Sale

Marketable securities, which are classified as available-for-sale, consisted of the following as of March 31, 2022 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash equivalents:
Money market funds	$	9,766	$	—	$	—		$	9,766
U.S. treasuries		2,000		—		—			2,000
Total cash equivalents		11,766		—		—			11,766
Short-term marketable securities:
U.S. government debt securities		3,016		—		(8	)		3,008
U.S. treasuries		59,877		—		(168	)		59,709
Total short-term marketable securities		62,893		—		(176	)		62,717
Total	$	74,659	$	—	$	(176	)	$	74,483

Marketable securities, which are classified as available-for-sale, consisted of the following as of December 31, 2021 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash equivalents:
Money market funds	$	21,421	$	—	$	—		$	21,421
Total cash equivalents		21,421		—		—			21,421
Short-term marketable securities:
U.S. government debt securities		3,026		—		(2	)		3,024
U.S. treasuries		52,186		—		(40	)		52,146
Total short-term marketable securities		55,212		—		(42	)		55,170
Long-term marketable securities
U.S. treasuries		1,995		—		(2	)		1,993
Total long-term marketable securities		1,995		—		(2	)		1,993
Total	$	78,628	$	—	$	(44	)	$	78,584

Term Loan Facility - Schedule of Future Principal Payments for Long-Term Debt (Details) - USD ($)
$ in Thousands

Mar. 31, 2022

Dec. 31, 2021

^[1]

Debt Disclosure [Abstract]

2022 (for the remaining 9 months)

$ 3,063

2023

9,813

2024

7,124

Total principal payments

20,000

End of term fee due at maturity in 2024

1,563

Total principal and end of term fee payments

21,563

Unamortized discount and debt issuance costs

(2,192)

Present value of remaining debt payments

19,371

Current portion of long-term debt

(4,837)

$ (3,055)

Long-term debt, net

$ 14,534

$ 18,409

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Commitments and Contingencies -Summary of Components of Lease Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Lease, Cost [Abstract]
Operating lease cost	$ 1,078	$ 1,096
Variable lease cost	296	466
Sublease income	(1,048)	(145)
Total lease cost	$ 326	$ 1,417

Stock-Based Compensation - Summary of Stock Option Activity (Details)	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Number of Shares
Balances at December 31, 2021 \| shares	8,666,955
Granted \| shares	1,897,085
Canceled \| shares	(717,266)
Balances at March 31, 2022 \| shares	9,846,774
Weighted-Average Exercise Price
Balances at December 31, 2021 \| $ / shares	$ 6.05
Granted \| $ / shares	1.06
Canceled \| $ / shares	6.15
Balances at March 31, 2022 \| $ / shares	$ 5.08

Equity Financing

3 Months Ended

Mar. 31, 2022

Equity [Abstract]

Equity Financing

9. Equity Financing

At-the-Market Offering

In June 2019, the Company filed a Registration Statement on Form S-3 (the “Shelf Registration Statement”), covering the offering of up to $250.0 million of common stock, preferred stock, debt securities, warrants, and units. The Shelf Registration Statement included a prospectus covering the offering, issuance and sale of up to $75.0 million of the Company’s common stock from time to time through an “at-the-market” offering under the Securities Act of 1933, as amended (the “Initial ATM Offering Program”). The SEC declared the Shelf Registration Statement effective on June 6, 2019.

In June 2019, the Company also entered into a sales agreement (the “June 2019 Sales Agreement”) with Cowen and Company, LLC (“Cowen”) to sell shares of the Company’s common stock, from time to time, with aggregate gross sales proceeds of up to $75.0 million, through the ATM Offering Program under which Cowen acts as its sales agent. Cowen is entitled to compensation for its services equal to up to 3.0% of the gross proceeds of any shares of common stock sold through Cowen under the June 2019 Sales Agreement. During the year ended December 31, 2020, the Company issued and sold 5,002,257 shares of its common stock through its ATM Offering Program and received net proceeds of approximately $37.3 million, after deducting commissions and other offering expenses of $1.3 million.

In July 2020, the Company filed an additional prospectus supplement to the Shelf Registration Statement. This prospectus supplement covers the offering, issuance and sale of up to an additional $50.0 million of the Company’s common stock from time to time through an additional “at-the-market” offering under the Securities Act of 1933, as amended (the “Additional ATM Offering Program”). The Initial ATM Offering Program and Additional ATM Offering Program are collectively (the “ATM Offering Programs”).

In July 2020, the Company entered into a second sales agreement (the “July 2020 Sales Agreement”) with Cowen to sell shares of the Company’s common stock, from time to time, with aggregate gross sales proceeds of up to $50.0 million, through the Additional ATM Offering Program under which Cowen will act as its sales agent. The issuance and sale of shares of common stock by the Company pursuant to the July 2020 Sales Agreement are also deemed an “at-the-market” offering under the Securities Act of 1933, as amended (the “Securities Act”). Cowen is entitled to compensation for its services equal to up to 3.0% of the gross proceeds of any shares of common stock sold through Cowen under the July 2020 Sales Agreement. During the three months ended March 31, 2022, there were 2,325,000 shares of the Company’s common stock sold through the Additional ATM Offering Program and received total net proceeds of approximately $3.4 million, after deducting commissions and other offering expenses of $0.1 million.

In March 2022, the Company entered into a third sales agreement (the “March 2022 Sales Agreement”) with Cowen to sell shares of the Company’s common stock, from time to time, with aggregate gross sales proceeds of up to $50.0 million.

Equity Purchase Agreement

On September 29, 2021, the Company entered into an equity purchase agreement (the “Purchase Agreement” or “Equity Purchase Agreement”) and a registration rights agreement with Lincoln Park Capital Fund, LLC (“Lincoln Park” or “Investor”) which provides for the sale to Lincoln Park up to $30,000,000 of shares (the “Purchase Shares”) of its common stock over the thirty-six (36) month term of the Purchase Agreement. In connection with the Purchase Agreement, Lincoln Park purchased 1,020,408 Purchase Shares at a purchase price of $2.94 per share, for a total gross purchase price of $3.0 million (the “Initial Purchase”), and the Company issued 252,447 shares of common stock to Lincoln Park as a commitment fee in connection with entering into the Purchase Agreement. The Company recognized $0.8 million of other expense relating to the commitment fee share issuance. As of December 31, 2021, the Company had initiated the purchase of an additional 2.9 million shares of the Company’s common stock amounting to $5.3 million in gross proceeds. During the three months ended March 31, 2022, the Company initiated purchases of an additional 0.9 million shares of the Company’s common stock amounting to $0.9 million in gross proceeds.

Under the Purchase Agreement, the Company has sole discretion, subject to certain conditions, on any business day selected by the Company to require Lincoln Park to purchase up to 100,000 shares of common stock (the “Regular Purchase Amount”) at the Purchase Price (as defined below) per purchase notice (each such purchase, a “Regular Purchase”). The Regular Purchase Amount may be increased as follows: to up to 150,000 shares if the closing price is not below $3.50, up to 200,000 shares if the closing price is not below $5.00, and up to 250,000 shares if the closing price is not below $7.00. Lincoln Park’s committed obligation under each Regular Purchase is capped at $2,000,000, unless the Parties agree otherwise. The purchase price for Regular Purchases (the “Purchase Price”) shall be equal to the lesser of: (i) the lowest sale price of the common shares during the Purchase Date, or (ii) the average of the three (3) lowest closing sale prices of the common shares during the ten (10) business days prior to the Purchase Date.

In addition to Regular Purchases and subject to certain conditions and limitations, the Company in its sole discretion may require Lincoln Park on each Purchase Date to purchase on the following business day up to the lesser of (i) three (3) times the number of shares purchased pursuant to such Regular Purchase or (ii) 30% of the trading volume on the Accelerated Purchase Date (the “Accelerated Purchase”) (unless the Parties agree otherwise) at a purchase price equal to the lesser of 97% of (i) the closing sale price on the Accelerated Purchase Date, or (ii) the Accelerated Purchase Date’s volume weighted average price (the “Accelerated Purchase Price”). The Company has the sole right to set a minimum price threshold for each Accelerated Purchase in the notice provided with respect to such Accelerated Purchase and under certain circumstances and in accordance with the Purchase Agreement the Company may direct multiple Accelerated Purchases in a day.

The aggregate number of shares that the Company can sell to Lincoln Park under the Purchase Agreement may not exceed 11,065,803 shares of the Common Shares (which is equal to approximately 19.99% of the shares of the Common Shares outstanding immediately prior to the execution of the Purchase Agreement) (the “Exchange Cap”), unless (i) shareholder approval is obtained to issue Purchase Shares above the Exchange Cap, in which the Exchange Cap will no longer apply, or (ii) the average price of all applicable sales of Common Shares to Lincoln Park under the Purchase Agreement equals or exceeds $2.94 per share; provided that at no time may Lincoln Park (together with its affiliates) beneficially own more than 9.99% of the Company’s issued and outstanding Common Shares.

The Purchase Agreement contains customary representations, warranties, covenants, closing conditions, indemnification and termination provisions. The Purchase Agreement may be terminated by the Company at any time, at its sole discretion, without any cost or penalty, by giving one business day notice to Lincoln Park. Further, Lincoln Park has covenanted not to engage in any direct or indirect short selling or hedging of the Common Shares. There are no limitations on the use of proceeds, financial or business covenants, restrictions on future financings (other than restrictions on the Company’s ability to enter into a similar type of agreement or Equity Line of Credit during the Term, excluding an At-The-Market transaction with a registered broker-dealer), rights of first refusal, participation rights, penalties or liquidated damages in the Purchase Agreement.

- Definition

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

+ References

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+ Details

Net Loss per Common Share

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Net Loss per Common Share

12. Net Loss per Common Share

Basic net loss per share is calculated by dividing net loss by the weighted-average number of shares outstanding for the period. Diluted net loss per share is calculated by dividing net loss by the weighted-average number of shares of common stock and potential dilutive common stock equivalents outstanding during the period if the effect is dilutive.

The calculation of diluted earnings (loss) per share also requires that, to the extent contingencies are satisfied during the period and the presumed issuance of additional shares as contingent consideration is dilutive to earnings (loss) per share for the period, adjustments to net income or net loss used in the calculation are required to remove the change in fair value of the contingent consideration liability for the period. Likewise, adjustments to the denominator are required to reflect the related dilutive shares. In all periods presented, the Company’s outstanding stock options, RSUs (including PSUs), early exercised common stock subject to future vesting, restricted stock accounted for as options, shares subject to the 2018 ESPP and presumed issuance of additional shares as contingent consideration were excluded from the calculation of diluted net loss per share because their effects were antidilutive.

A reconciliation of the numerators and denominators used in computing net loss from continuing operations per share is as follows (in thousands, except share and per share amounts):

	Three months ended March 31,
	2022			2021
Numerator:
Net loss	$	(18,915	)	$	(15,756	)
Denominator:
Weighted-average number of shares outstanding—basic and diluted		67,528,552			54,169,349
Net loss per share—basic and diluted	$	(0.28	)	$	(0.29	)

Since the Company was in a net loss position for all periods presented, basic net loss per common share is the same as diluted net loss per common share as the inclusion of all potential common shares outstanding would have been anti-dilutive.

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	March 31,
	2022		2021
Options to purchase common stock		9,846,774		7,405,619
Early exercised common stock subject to future vesting		33,370		33,370
RSUs		1,998,358		2,830,632
Shares subject to 2018 ESPP		145,017		57,568
Total		12,023,519		10,327,189

Up to 55,900 shares may be contingently issued, if certain performance conditions are met under the Company’s in-licensing agreements. See Note 5, “License Revenue and Agreements,” to our condensed financial statements for additional information.

Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

11. Stock-Based Compensation

Stock Options and Restricted Stock Units Activity

A summary of the Company’s stock option activity under the 2013 Equity Incentive Plan, 2018 Incentive Award Plan, and 2020 Employment Inducement Incentive Plan for the three months ended March 31, 2022 is as follows:

	Number of Shares			Weighted- Average Exercise Price
Balances at December 31, 2021		8,666,955		$	6.05
Granted		1,897,085		$	1.06
Exercised		—		$	—
Canceled		(717,266	)	$	6.15
Balances at March 31, 2022		9,846,774		$	5.08

A summary of the Company’s restricted stock units (“RSUs”), performance stock units (“PSUs”), and restricted stock awards (“RSAs”) activity for the three months ended March 31, 2022 is as follows:

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested at December 31, 2021		1,990,937		$	3.92
Granted		463,328		$	1.06
Vested		(303,588	)	$	4.48
Canceled		(152,319	)	$	3.54
Unvested at March 31, 2022		1,998,358		$	3.20

For stock options granted to employees with service-based vesting, the fair value of stock options granted to employees was estimated on the date of grant using the Black-Scholes option pricing model and utilizing assumptions that were determined as follows:

Expected Term—The expected term represents the period that the options granted are expected to be outstanding and is determined using the simplified method (based on the mid-point between the vesting date and the end of the contractual term) as the Company has concluded that its stock option exercise history does not provide a reasonable basis upon which to estimate expected term.

Expected Volatility—Due to limited historical data, the Company estimates stock price volatility based on a combined weighted-average of the Company’s historical average volatility and that of a selected peer group of comparable publicly traded companies within the biotechnology and pharmaceutical industry that were deemed to be representative of future stock price trends over the expected life of the award.

Risk-Free Interest Rate—The Company based the risk-free interest rate over the expected term of the options based on the constant maturity rate of U.S. Treasury securities with similar maturities as of the date of the grant.

Expected Dividends—The Company has never paid any dividends and does not plan to pay dividends in the foreseeable future. Therefore, the expected dividend yield is zero.

In March 2020, the board of directors granted the Company’s newly hired Chief Executive Officer stock-based awards covering an aggregate of 1.1 million shares of common stock, including options to purchase an aggregate of 800,000 shares of common stock, 120,000 RSUs, 150,000 PSUs, and 30,000 shares of common stock. The stock-based awards were granted pursuant to the 2020 Employment Inducement Incentive Plan, which was approved by the board of directors in March 2020 to provide for grants to newly hired employees as a material inducement for them to commence employment with the Company.

The 30,000 shares of common stock were fully vested on the date of grant and thus, the related compensation expense of $0.2 million was recognized on the grant date. The stock options and RSUs will vest subject to continued service through the applicable vesting date.

The PSUs were originally scheduled to vest as to 50,000 PSUs upon the attainment of (a) a volume-weighted average per share closing trading price of the Company’s common stock of at least $36.875 over a trailing 30-day period or (b) a change in control transaction in which the price per share to the holders of the Company’s common stock is at least $36.875 and as to 100,000 PSUs (x) at such time as the Company’s market capitalization reaches at least $2.5 billion, as measured based on the volume weighted-average closing trading price over a trailing 30 day period or (y) a change in control transaction in which the consideration paid to the Company’s stockholders is equal to at least $2.5 billion, as determined by the Company’s board of directors. In January 2021, the board of directors modified the PSUs to vest as to 50,000 PSUs upon the attainment of (a) a volume-weighted average per share closing trading price of the Company’s common stock of at least $18 over a trailing 30-day period or (b) a change in control transaction in which the price per share to the holders of the Company’s common stock is at least $18.00 and as to 100,000 PSUs upon the attainment of (x) a volume-weighted average per share closing trading price of the Company’s common stock of at least $36.00 over a trailing 30-day period or (y) a change in control transaction in which the price per share to the holders of the Company’s common stock is at least $36.00, as determined by the Company’s board of directors.

For the PSU awards, the Company used the Monte-Carlo option pricing model to determine the fair value of awards at the date of grant. The Monte-Carlo option pricing model uses similar input assumptions as the Black-Scholes model; however, it further incorporates into the fair-value determination the possibility that the market condition may not be satisfied. Compensation costs related to awards with a market-based condition are recognized regardless of whether the market condition is ultimately satisfied. Compensation cost is not reversed if the achievement of the market condition does not occur. The total grant date fair value of the PSU awards was determined to be $0.7 million and will be recognized as compensation expense over the weighted-average derived service period of approximately 4.3 years. The incremental fair value of the PSUs on the modification date of $31,000 are added to the unamortized value of the original grant of $569,000 and will be amortized to expense over the new implied service periods of 1.63 years to 2.79 years.

In February 2022, the Company’s board of directors approved the granting of retention awards to critical and important Company personnel. The awards consisted of 1,893,335 stock options and 463,328 restricted stock units with a grant date total fair value of $2.0 million and $0.5 million, respectively.

Performance and Market Contingent Stock Options

In January 2021, the board of directors modified 17,479 performance and market contingent stock options with vesting conditions that required the combination of a liquidity event, change of control or IPO with a market condition at prescribed levels. The modification removed the performance condition and lowered the market conditions to a volume-weighted average per share closing trading price of the Company’s common stock of at least

$18.00 over a trailing 30-day period for one tranche and at least $36.00 over a trailing 30-day period for the second tranche. The fair value of the options on the modification date of $81,000 will be amortized to expense over the implied service periods of 1.46 years to 2.52 years.

In June 2021, the board of directors modified 33,370 performance and market contingent stock options with vesting conditions that required the combination of a liquidity event, change of control or IPO with a market condition at prescribed levels. The modification removed the performance condition and adjusted the market conditions to a date on which the Company attains a valuation of at least one billion dollars measured by the volume-weighted average per share closing trading price of the Company’s common stock over a trailing 30-day period. The fair value of the options on the modification date of $102,000 will be amortized to expense over the implied service periods of 1.85 years.

As of March 31, 2022, there were 50,849 market contingent stock option awards outstanding with a total fair value of $0.2 million.

Stock Based Compensation Expense

The following table sets forth the total stock-based compensation expense for all options granted to employees and nonemployees, including shares sold through the issuance of non-recourse promissory notes which are considered to be options for accounting purposes, and costs associated with the Company’s 2018 Employee Stock Purchase Plan (“2018 ESPP”) included in the Company’s condensed statements of operations and comprehensive loss (in thousands):

	Three months ended March 31,
	2022		2021
Research and development	$	1,004	$	1,081
General and administrative		1,656		1,663
Total	$	2,660	$	2,744

There was no stock-based compensation expense related to awards accounted for as liability awards for the three months ended March 31, 2022 and 2021.

Commitments and Contingencies - Additional Information (Details)	1 Months Ended			3 Months Ended		12 Months Ended
	Jun. 30, 2021 ft² $ / ft²	May 31, 2021 ft² $ / ft²	Feb. 28, 2021 USD ($) ft² $ / ft²	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Commitments And Contingencies [Line Items]
Sublease income				$ 1,048,000	$ 145,000
South San Francisco, California
Commitments And Contingencies [Line Items]
Lessee, operating lease, description				In February 2019, the Company entered into a lease agreement for new office and laboratory space in South San Francisco, California. The term of the lease agreement commenced in May 2019. The lease has an initial term from occupancy of approximately ten years ending on December 31, 2029 with an option to extend the term for an additional eight years at then-market rental rates
Lease commencement date				2019-05
Lease expiration date				Dec. 31, 2029
Operating lease, initial lease term				10 years
Operating lease, option to extend description				option to extend the term for an additional eight years
Operating lease, existence of option to extend				true
Operating lease, renewal term				8 years
Tenant improvement allowance							$ 10,700,000
Letter of credit delivered in connection with lease agreement				$ 900,000
Estimated discount rate				3.50%
Impairment loss				$ 0		$ 2,600,000
Space subleased (in sqaure feet) \| ft²	23,000
Sublease expiration date	Aug. 31, 2024
Sublease rent per square foot \| $ / ft²	6.25
Annual percentage increase in sublease base rent	3.50%
Percentage of operating expenses and property management fees to be paid by subtenant	37.00%
Sublease income				$ 600,000	0
Brisbane, California
Commitments And Contingencies [Line Items]
Lease commencement date				2016-05
Operating lease, option to extend description				The lease agreement includes an escalation clause for increased rent and a renewal provision allowing the Company to extend this lease for an additional four years by giving the landlord written notice of the election to exercise the option at least fifteen months prior to the original expiration of the lease term.
Operating lease, renewal term				4 years
Tenant improvement allowance				$ 3,900,000
Lease expiration date				2022-10
Space subleased (in sqaure feet) \| ft²		11,500	27,000
Sublease expiration date		Sep. 30, 2022	Aug. 31, 2022
Sublease rent per square foot \| $ / ft²		1.00	3.53
Annual percentage increase in sublease base rent			3.00%
Percentage of operating expenses and property management fees to be paid by subtenant		30.00%	41.00%
Incurred initial direct costs of sublease			$ 100,000
Sublease income				$ 500,000	$ 100,000

Net Loss per Common Share (Tables)

3 Months Ended

Mar. 31, 2022

Earnings Per Share [Abstract]

Schedule of Reconciliation of Numerators and Denominators Used In Computing Net Loss From Continuing Operations Per Share

A reconciliation of the numerators and denominators used in computing net loss from continuing operations per share is as follows (in thousands, except share and per share amounts):

	Three months ended March 31,
	2022			2021
Numerator:
Net loss	$	(18,915	)	$	(15,756	)
Denominator:
Weighted-average number of shares outstanding—basic and diluted		67,528,552			54,169,349
Net loss per share—basic and diluted	$	(0.28	)	$	(0.29	)

Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Per Share

Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:

	March 31,
	2022		2021
Options to purchase common stock		9,846,774		7,405,619
Early exercised common stock subject to future vesting		33,370		33,370
RSUs		1,998,358		2,830,632
Shares subject to 2018 ESPP		145,017		57,568
Total		12,023,519		10,327,189

Marketable Securities - Additional Information (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2022	Dec. 31, 2021
Marketable Securities [Line Items]
Realized gains or losses on available-for-sale debt securities	$ 0	$ 0
Maximum
Marketable Securities [Line Items]
Available-for sale securities, remaining contractual maturity	1 year

Condensed Balance Sheets (Parenthetical) (Unaudited) - $ / shares	Mar. 31, 2022	Dec. 31, 2021
Statement Of Financial Position [Abstract]
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares authorized	10,000,000	10,000,000
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	300,000,000	300,000,000
Common stock, shares issued	69,148,106	62,991,906
Common stock, shares outstanding	69,148,106	62,991,906

Net Loss per Common Share - Summary of Potentially Dilutive Securities Excluded from Computation of Diluted Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	12,023,519	10,327,189
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	9,846,774	7,405,619
Early Exercised Common Stock Subject to Future Vesting
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	33,370	33,370
RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	1,998,358	2,830,632
Shares Subject to 2018 ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from computation of diluted net loss per share	145,017	57,568

Condensed Statements of Cash Flows (Unaudited) - USD ($)
$ in Thousands

3 Months Ended

12 Months Ended

Mar. 31, 2022

Mar. 31, 2021

Dec. 31, 2021

Operating activities

Net loss

$ (18,915)

$ (15,756)

Adjustments to reconcile net loss to net cash used in operating activities:

Depreciation and amortization

627

757

Amortization of debt issuance costs

322

191

Debt extinguishment gain upon conversion to equity

(199)

Net accretion and amortization of premium and discounts on marketable securities

131

290

Stock-based compensation

2,660

2,744

Non-cash rent expense

(626)

(556)

Changes in operating assets and liabilities:

Prepaid expenses and other current assets

110

1,585

Other long-term assets

Accounts payable

1,345

(640)

Accrued compensation

(1,191)

(3,516)

Accrued liabilities and other current liabilities

774

(190)

Other long-term liabilities

(24)

Net cash used in operating activities

(14,972)

(15,091)

Investing activities

Purchase of marketable securities

(17,067)

(38,174)

Maturities of marketable securities

11,250

52,250

Purchase of property and equipment

(14)

Net cash provided by investing activities

(5,817)

14,062

Financing activities

Proceeds from issuance of common stock upon exercise of stock options, net of repurchases

1,172

Net cash provided by financing activities

4,330

10,064

Net increase (decrease) in cash, cash equivalents and restricted cash

(16,459)

9,035

Cash, cash equivalents and restricted cash at beginning of the period

34,351

19,253

$ 19,253

Cash, cash equivalents and restricted cash at end of the period

17,892

28,288

34,351

Supplemental Disclosures of Cash Flow Information:

Cash paid for interest

518

584

Supplemental Disclosures of Non-Cash Investing and Financing Activities

Issuance of common stock in payment of debt

3,178

Property and equipment included in accounts payable and accrued liabilities

Cash and cash equivalents

16,446

26,842

$ 32,905

^[1]

Restricted cash

1,446

ATM Offering Program

Financing activities

Proceeds from issuance of common stock, net of issuance costs

3,420

8,892

Lincoln Park Capital Fund

Financing activities

Proceeds from issuance of common stock, net of issuance costs

$ 910

$ 0

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2022

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Stock Option Activity

	Number of Shares			Weighted- Average Exercise Price
Balances at December 31, 2021		8,666,955		$	6.05
Granted		1,897,085		$	1.06
Exercised		—		$	—
Canceled		(717,266	)	$	6.15
Balances at March 31, 2022		9,846,774		$	5.08

Summary of Restricted Stock Units, Performance Stock Units and Restricted Stock Awards Activity

	Number of Shares			Weighted- Average Grant Date Fair Value
Unvested at December 31, 2021		1,990,937		$	3.92
Granted		463,328		$	1.06
Vested		(303,588	)	$	4.48
Canceled		(152,319	)	$	3.54
Unvested at March 31, 2022		1,998,358		$	3.20

Summary of Stock-based Compensation Expense

	Three months ended March 31,
	2022		2021
Research and development	$	1,004	$	1,081
General and administrative		1,656		1,663
Total	$	2,660	$	2,744

Organization - Additional Information (Details) - USD ($)
$ in Thousands

3 Months Ended

Mar. 31, 2022

Mar. 31, 2021

Dec. 31, 2021

^[1]

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Accumulated deficit

$ (418,939)

$ (400,024)

Net loss

(18,915)

$ (15,756)

Cash used in operations

(14,972)

(15,091)

Product revenue

$ 0

Cash, cash equivalents and marketable securities

$ 79,200

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

- Definition

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

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+ Details

- Definition

The cumulative amount of the reporting entity's undistributed earnings or deficit.

+ References + Details

- Definition

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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+ Details

Term Loan Facility

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Term Loan Facility

7. Term Loan Facility

On August 3, 2020, the Company entered into a Loan and Security Agreement (the “Loan Agreement”) with Hercules Capital, Inc. (“Hercules”). Under the Loan Agreement, Hercules provided the Company with access to a term loan with an aggregate principal amount of up to $80.0 million (the “Term Loan Facility”), available in four tranches, subject to certain terms and conditions. The first tranche of $25.0 million was advanced to the Company on the date the Loan Agreement was executed. The milestones for the remaining tranches have not yet been reached and as of March 31, 2022 are not expected to be reached as they were dependent, in whole or in part, upon continued advancement in the clinical development of UBX0101 in patients with osteoarthritis of the knee.

On December 15, 2021, the Company entered into an amendment to the Loan and Security Agreement (“the Loan Amendment”). The Loan Amendment includes a Lender Optional Conversion where after the effective date and until the six-month anniversary of the execution date, the lender may elect to convert to equity of the Company all or any part of up to twenty percent (20%) of the original principal amount for a maximum amount of $5.0 million. As of December 31, 2021, the lender had elected to convert $2.3 million of the outstanding principal into equity. The Company incurred approximately $0.1 million in loan issuance costs relating to the amendment, which were offset against the loan proceeds and are accounted for as a loan discount.

During the first quarter of 2022, Hercules Capital, Inc. gave notice to convert the remaining convertible debt option into equity of the Company’s common stock. This resulted in the conversion of $2.7 million of principal debt into common stock, and reducing the outstanding principal under the first tranche to $20.0 million.

The Company expects to make interest only payments through September 1, 2022 and expects to then repay the principal balance and interest in equal monthly installments through August 1, 2024. Pursuant to the Loan Amendment, the interest only period may extend up to a maximum of 9 months to June 1, 2023 should the company meet specific milestones related to its clinical trials and raising additional capital.

The Company may prepay advances under the Loan Agreement, in whole or in part, at any time subject to a prepayment charge of up to 1.50% of any amount prepaid, depending upon when the prepayment occurs. Upon prepayment or repayment of all or any of the term loans under the Term Loan Facility, the Company is required to pay an end of term fee (“End of Term Fee”) equal to 6.25% of the total aggregate amount of the term loans being prepaid or repaid, which has been recorded as a discount on the principal balance upon issuance.

Interest on the term loan accrues at a per annum rate equal to the greater of (i) the Wall Street Journal prime rate plus 6.10% and (ii) 9.35%. On March 17, 2022, the prime rate was raised to 3.50%. On March 31, 2022, the interest rate on the term loan was 9.60%. Interest expense is calculated using the effective interest method and is inclusive of non-cash amortization of capitalized loan issuance costs. At March 31, 2022, the effective interest rate was 17.26%.

Under the terms of the Loan Agreement, the Company granted first priority liens and security interests in substantially all of the Company’s assets, other than intellectual property, as collateral for the obligations thereunder. The Company also granted Hercules the right, at their discretion, to participate in any closing of any single subsequent financing as defined up to a maximum aggregate amount of $2.0 million. The Loan Agreement also contains representations and warranties by the Company and Hercules, indemnification provisions in favor of Hercules and customary affirmative and negative covenants (including a liquidity covenant beginning July 1, 2021, requiring the Company to maintain at least $15.0 million in unrestricted cash), and events of default, including a material adverse change in the Company’s business, payment defaults, breaches of covenants following any applicable cure period, and a material impairment in the perfection or priority of Hercules’ security interest in the collateral. The substantial doubt regarding the Company’s ability to continue as a going concern does not constitute a material adverse event under the terms of the Loan Agreement. In the event of default by the Company under the Loan Agreement, the Company may be required to repay all amounts then outstanding under the Loan Agreement.

We have determined that the risk of subjective acceleration under the material adverse events clause included in the Loan Agreement is remote and, therefore, have classified the outstanding principal amount in current and long-term liabilities based on the timing of scheduled principal payments. As of March 31, 2022, and as of the date of the issuance of these financial statements, the Company was in compliance with all covenants and has not been notified of an event of default by the lender under the Loan Agreement.

As of March 31, 2022, the carrying value of the term loan consists of $20.0 million principal outstanding less the debt discount and issuance costs of approximately $2.2 million. The End of Term Fee of $1.6 million is recognized over the life of the term loan as interest expense using the effective interest method. The debt issuance costs have been recorded as a debt discount which are being accreted to interest expense through the maturity date of the term loan.

Interest expense relating to the term loan, which is included in interest expense in the condensed statements of operations and comprehensive loss, was $0.8 million and $0.8 million for the three months ended March 31, 2022 and 2021, respectively.

Future principal payments for the long-term debt as of March 31, 2022 are as follows (in thousands):

	Amount
2022 (for the remaining 9 months)	$	3,063
2023		9,813
2024		7,124
Total principal payments		20,000
End of term fee due at maturity in 2024		1,563
Total principal and end of term fee payments		21,563
Unamortized discount and debt issuance costs		(2,192	)
Present value of remaining debt payments		19,371
Current portion of long-term debt		(4,837	)
Long-term debt, net	$	14,534

- Definition

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-URI http://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (h)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(c))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1C
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495334-112611

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1E
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495348-112611

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1I
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495371-112611

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

+ Details

Stock-Based Compensation - Summary of Restricted Stock Units, Performance Stock Units and Restricted Stock Awards Activity (Details) - RSU, RSA and PSU	3 Months Ended
	Mar. 31, 2022 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares, Unvested at December 31, 2021 \| shares	1,990,937
Shares, Granted \| shares	463,328
Shares, Vested \| shares	(303,588)
Shares, Canceled \| shares	(152,319)
Shares, Unvested at March 31, 2022 \| shares	1,998,358
Weighted-Average Grant Date Fair Value, Unvested at December 31, 2021 \| $ / shares	$ 3.92
Weighted-Average Grant Date Fair Value, Granted \| $ / shares	1.06
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	4.48
Weighted-Average Grant Date Fair Value, Canceled \| $ / shares	3.54
Weighted-Average Grant Date Fair Value, Unvested at March 31, 2022 \| $ / shares	$ 3.20

Condensed Balance Sheets (Unaudited) - USD ($)
$ in Thousands

Mar. 31, 2022

Dec. 31, 2021

^[1]

Current assets:

Cash and cash equivalents

$ 16,446

$ 32,905

Short-term marketable securities

62,717

55,170

Prepaid expenses and other current assets

1,770

1,879

Restricted cash

550

Total current assets

81,483

90,504

Property and equipment, net

9,308

9,942

Operating lease right-of-use assets

20,706

21,286

Long-term marketable securities

1,993

Long-term restricted cash

896

Other long-term assets

Total assets

112,469

124,712

Current liabilities:

Accounts payable

3,323

1,985

Accrued compensation

2,837

4,028

Accrued and other current liabilities

6,692

6,370

Deferred revenue

216

Derivative liability related to debt

963

Current portion of long-term debt

4,837

3,055

Total current liabilities

17,905

16,617

Operating lease liability, net of current portion

29,339

30,094

Long-term debt, net

14,534

18,409

Other long-term liabilities

Total liabilities

61,778

65,143

Commitments and contingencies (Note 6)

Stockholders’ equity:

Convertible preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding

Common stock, $0.0001 par value; 300,000,000 shares authorized as of March 31, 2022 and December 31, 2021; 69,148,106 and 62,991,906 shares issued and outstanding as of March 31, 2022 and December 31, 2021, respectively

Additional paid-in capital

469,799

459,631

Accumulated other comprehensive loss

(176)

(44)

Accumulated deficit

(418,939)

(400,024)

Total stockholders’ equity

50,691

59,569

Total liabilities and stockholders’ equity

$ 112,469

$ 124,712

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Marketable Securities - Summary of Marketable Securities Classified as Available-for-Sale (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	$ 74,659	$ 78,628
Unrealized Gains	0	0
Unrealized Losses	(176)	(44)
Fair Value	74,483	78,584
Cash Equivalents
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	11,766	21,421
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	11,766	21,421
Cash Equivalents \| Money market funds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	9,766	21,421
Unrealized Gains	0	0
Unrealized Losses	0	0
Fair Value	9,766	21,421
Cash Equivalents \| U S Treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	2,000
Unrealized Gains	0
Unrealized Losses	0
Fair Value	2,000
Short Term Marketable Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	62,893	55,212
Unrealized Gains	0	0
Unrealized Losses	(176)	(42)
Fair Value	62,717	55,170
Short Term Marketable Securities \| U.S. government debt securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	3,016	3,026
Unrealized Gains	0	0
Unrealized Losses	(8)	(2)
Fair Value	3,008	3,024
Short Term Marketable Securities \| U S Treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	59,877	52,186
Unrealized Gains	0	0
Unrealized Losses	(168)	(40)
Fair Value	$ 59,709	52,146
Long Term Marketable Securities
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis		1,995
Unrealized Gains		0
Unrealized Losses		(2)
Fair Value		1,993
Long Term Marketable Securities \| U S Treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis		1,995
Unrealized Gains		0
Unrealized Losses		(2)
Fair Value		$ 1,993

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Basis of Presentation

These condensed financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and the rules and regulations of the United States Securities and Exchange Commission (“SEC”) for interim reporting.

Certain information and footnote disclosures normally included in annual financial statements prepared in accordance with GAAP have been condensed or omitted. Accordingly, the unaudited condensed financial statements should be read in conjunction with the audited financial statements and the related notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2021 filed with the SEC.

Unaudited Condensed Financial Statements

The accompanying financial information for the three months ended March 31, 2022 and 2021 are unaudited. The unaudited condensed financial statements have been prepared on the same basis as the annual audited financial statements and, in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary to present fairly the Company’s financial position as of March 31, 2022 and its results of operations for the three months ended March 31, 2022 and 2021 and cash flows for the three months ended March 31, 2022 and 2021. The results for interim periods are not necessarily indicative of the results expected for the full fiscal year or any other periods.

Use of Estimates

The condensed financial statements have been prepared in accordance with GAAP, which requires management to make estimates and assumptions that affect the amounts and disclosures reported in the condensed financial statements and accompanying notes. The Company bases its estimates on historical experience and market-specific or other relevant assumptions that it believes are reasonable under the circumstances. The amounts of assets and liabilities reported in the Company’s condensed balance sheets and the amount of expenses and income reported for each of the periods presented are affected by estimates and assumptions, which are used for, but are not limited to, determining the fair value of assets and liabilities, contingent consideration liability, the fair value of right-of-use assets and lease liabilities, derivative liabilities related to debt and stock-based compensation. Actual results could differ from such estimates or assumptions.

Segments

The Company has one operating segment. The Company’s chief operating decision maker, its Chief Executive Officer, manages the Company’s operations on a consolidated basis for the purposes of allocating resources.

Restructurings

Restructuring

The Company recognizes restructuring charges related to reorganization plans that have been committed to by management and when liabilities have been incurred. In connection with these activities, the Company records restructuring charges at fair value for a) contractual employee termination benefits when obligations are associated to services already rendered, rights to such benefits have vested, and payment of benefits is probable and can be reasonably estimated, and b) one-time employee termination benefits when management has committed to a plan of termination, the plan identifies the employees and their expected termination dates, the details of termination benefits are complete, it is unlikely changes to the plan will be made or the plan will be withdrawn and communication to such employees has occurred.

One-time employee termination benefits are recognized in their entirety when communication has occurred, and future services are not required. Contract termination costs to be incurred over the remaining contract term without economic benefit are recorded in their entirety when the contract is canceled.

The recognition of restructuring charges requires the Company to make certain judgments and estimates regarding the nature, timing and amount of costs associated with the planned reorganization plan. At the end of each reporting period, the Company evaluates the remaining accrued restructuring balances to ensure that no excess accruals are retained, and the utilization of the provisions are for their intended purpose in accordance with developed restructuring plans.

Recently Issued Accounting Pronouncements Not Yet Adopted

In October 2020, the FASB issued ASU 2020-10, Codification Improvements. The ASU contains improvements to the Codification by ensuring that all guidance that requires or provides an option for an entity to provide information in the notes to financial statements is codified in the disclosure section of the Codification. The ASU also improves various topics in the Codification so that entities can apply guidance more consistently on codifications that are varied in nature where the original guidance may have been unclear. The amendments in ASU 2020-10 are effective for the Company for fiscal years beginning after December 15, 2021, and interim periods within fiscal years beginning after December 15, 2022. Early adoption is permitted. The Company does not expect the adoption of ASU 2020-10 to have a material impact on its financial statements and related disclosures.

In August 2020, the FASB issued ASU No. 2020-06, Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging—Contracts in Entity’s Own Equity. ASU 2020-06 eliminates the beneficial conversion and cash conversion accounting models for convertible instruments. It also amends the accounting for certain contracts in an entity’s own equity that are currently accounted for as derivatives because of specific settlement provisions. In addition, ASU 2020-06 modifies how particular convertible instruments and certain contracts that may be settled in cash or shares impact the diluted EPS computation. The amendments in ASU 2020-06 are effective for smaller reporting companies as defined by the SEC for fiscal years beginning after December 15, 2023, including interim periods within those fiscal years. Early adoption is permitted, but no earlier than fiscal years beginning after December 15, 2020. The Company is currently evaluating the impact of ASU 2020-06 on its financial statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments—Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments, as clarified in subsequent amendments. ASU 2016-13 changes the impairment model for certain financial instruments. The new model is a forward-looking expected loss model and will apply to financial assets subject to credit losses and measured at amortized cost and certain off-balance sheet credit exposures. This includes loans, held-to-maturity debt securities, loan commitments, financial guarantees and net investments in leases, as well as trade receivables. For available-for-sale debt securities with unrealized losses, credit losses will be measured in a manner similar to today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. In October 2019, the FASB voted to delay the effective date of this standard. Topic 326 will be effective for the Company for fiscal years beginning after December 15, 2022. Early adoption is permitted. The Company is currently assessing the effect that this ASU will have on its financial position, results of operations, and disclosures.

Fair Value Measurements

The Company determines the fair value of financial and non-financial assets and liabilities based on the assumptions that market participants would use in pricing the asset or liability in an orderly transaction between market participants at the measurement date. The identification of market participant assumptions provides a basis for determining what inputs are to be used for pricing each asset or liability. A fair value hierarchy has been established which gives precedence to fair value measurements calculated using observable inputs over those using unobservable inputs. This hierarchy prioritized the inputs into three broad levels as follows:

•

Level 1: Quoted prices in active markets for identical instruments

•

Level 2: Other significant observable inputs (including quoted prices in active markets for similar instruments)

•

Level 3: Significant unobservable inputs (including assumptions in determining the fair value of certain investments)

The Company estimates the fair value of its money market funds, U.S. and foreign commercial paper, U.S. and foreign corporate debt securities, U.S. treasuries, and U.S. government debt securities by taking into consideration valuations obtained from third-party pricing services. The pricing services utilize industry standard valuation models, including both income and market-based approaches, for which all significant inputs are observable, either directly or indirectly, to estimate fair value. These inputs include reported trades of and broker/dealer quotes on the same or similar securities, issuer credit spreads; benchmark securities; prepayment/default projections based on historical data; and other observable inputs.

Marketable Securities

3 Months Ended

Mar. 31, 2022

Investments Debt And Equity Securities [Abstract]

Marketable Securities

4. Marketable Securities

Marketable securities, which are classified as available-for-sale, consisted of the following as of March 31, 2022 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash equivalents:
Money market funds	$	9,766	$	—	$	—		$	9,766
U.S. treasuries		2,000		—		—			2,000
Total cash equivalents		11,766		—		—			11,766
Short-term marketable securities:
U.S. government debt securities		3,016		—		(8	)		3,008
U.S. treasuries		59,877		—		(168	)		59,709
Total short-term marketable securities		62,893		—		(176	)		62,717
Total	$	74,659	$	—	$	(176	)	$	74,483

Marketable securities, which are classified as available-for-sale, consisted of the following as of December 31, 2021 (in thousands):

	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Cash equivalents:
Money market funds	$	21,421	$	—	$	—		$	21,421
Total cash equivalents		21,421		—		—			21,421
Short-term marketable securities:
U.S. government debt securities		3,026		—		(2	)		3,024
U.S. treasuries		52,186		—		(40	)		52,146
Total short-term marketable securities		55,212		—		(42	)		55,170
Long-term marketable securities
U.S. treasuries		1,995		—		(2	)		1,993
Total long-term marketable securities		1,995		—		(2	)		1,993
Total	$	78,628	$	—	$	(44	)	$	78,584

At March 31, 2022, the remaining contractual maturities of available-for-sale securities were less than one year. There have been no significant realized gains or losses on available-for-sale securities for the periods presented. Available-for-sale debt securities that were in a continuous loss position but were not deemed to be other than temporarily impaired were immaterial at both March 31, 2022 and December 31, 2021. The Company does not intend to and believes it is not more likely than not that it will be required to sell these debt securities before their maturities.

See Note 3, “Fair Value Measurements,” for further information regarding the fair value of the Company’s financial instruments.

Related-Party Transactions - Additional Information (Details) - USD ($)	1 Months Ended		3 Months Ended		12 Months Ended
	Dec. 31, 2019	Jan. 31, 2018	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Non-executive Officer \| Promissory Note
Related Party Transaction [Line Items]
Due from related parties	$ 200,000	$ 200,000
Promissory notes for purchase of common stock				$ 200,000
Interest rate	1.51%	2.50%
Non-executive Officer \| Promissory Note \| Common Stock
Related Party Transaction [Line Items]
Early exercise options in aggregate		59,322
License Agreement \| Jocasta Neuroscience Inc
Related Party Transaction [Line Items]
Upfront cash payments received					$ 5,000,000.0
Deferred revenue recognized			$ 0	$ 0	$ 4,800,000

Commitments and Contingencies

3 Months Ended

Mar. 31, 2022

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

6. Commitments and Contingencies

Leases

In February 2019, the Company entered into a lease agreement for new office and laboratory space in South San Francisco, California. The term of the lease agreement commenced in May 2019. The lease has an initial term from occupancy of approximately ten years ending on December 31, 2029 with an option to extend the term for an additional eight years at then-market rental rates. The total base rent payment escalates annually based on a fixed percentage beginning from the 13^th month of the lease agreement. The Company will also be responsible for the operating expenses and real estate taxes allocated to the building and common areas. Pursuant to the lease agreement, the landlord provided the Company with a tenant improvement allowance of $10.7 million, which was included in deferred rent and leasehold improvements on the balance sheet at December 31, 2019. In connection with the execution of the lease agreement, the Company delivered a letter of credit of approximately $0.9 million to the landlord.

In May 2016, the Company executed a non-cancellable lease agreement for office and laboratory space in Brisbane, California which commenced in May 2016 and continues through October 2022. The lease agreement includes an escalation clause for increased rent and a renewal provision allowing the Company to extend this lease for an additional four years by giving the landlord written notice of the election to exercise the option at least fifteen months prior to the original expiration of the lease term. The lease provides for monthly base rent amounts escalating over the term of the lease and the lessor provided the Company a $3.9 million tenant improvement allowance to complete the laboratory and office renovation which was recorded as deferred rent liability and leasehold improvements within property and equipment, net. In May 2017, the Company entered into an amendment to expand the leased space and received a three-month rent holiday for the expanded space.

The Company’s operating leases include various covenants, indemnities, defaults, termination rights, security deposits and other provisions customary for lease transactions of this nature.

The following table summarizes the components of lease expense, which are included in operating expenses in the Company’s condensed statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2022			2021
Operating lease cost	$	1,078		$	1,096
Variable lease cost		296			466
Sublease income		(1,048	)		(145	)
Total lease cost	$	326		$	1,417

Variable lease payments include amounts relating to common area maintenance, real estate taxes and insurance and are recognized in the condensed statements of operations and comprehensive loss as incurred.

The following table summarizes supplemental information related to leases (in thousands):

	Three Months Ended March 31,
	2022			2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	1,704		$	1,652
Weighted-average remaining lease term (years)
Operating leases		7.8			8.3
Weighted-average discount rate (percentage)
Operating leases		6.0	%		5.9	%

The following table summarizes the maturities of lease liabilities as of March 31, 2022 (in thousands):

	Amount
2022 (remaining 9 months)	$	4,579
2023		4,810
2024		4,964
2025		5,123
2026		5,287
Thereafter		16,893
Total future minimum lease payments		41,656
Less: Amount representing interest		(8,391	)
Present value of future minimum lease payments		33,265
Less: Current portion of operating lease liability		(3,926	)
Noncurrent portion of operating lease liability	$	29,339

In February 2020, the Company completed its move into the new office and laboratory space in South San Francisco, exited its previous offices and laboratory space in Brisbane, California, and began to actively market this space for sublease. Concurrent with this move and in consideration of real estate market conditions, in particular due to the COVID-19 pandemic in March 2020, the Company identified indicators of impairment in the related asset group, which included the leased ROU asset and related leasehold improvements associated with the lease. The Company subsequently evaluated and compared the net book value of the asset group to the estimated undiscounted future cash flows over the remaining term of the lease and concluded that an impairment had occurred. The discounted estimated future cash flows included estimates of sublease rentals through the end of the lease term, which ends on October 31, 2022, utilizing a discount rate of 3.5% based on the Company’s estimated incremental borrowing rate at that time. The estimated discounted cash flows were compared to the net book value of the ROU asset and leasehold improvements resulting in an impairment loss of $2.6 million during the year ended December 31, 2020, which was included in operating expense in the statements of operations and comprehensive loss. No impairment loss was recorded during the three months ended March 31, 2022.

In February 2021, the Company entered into an agreement to sublease the first floor of the Brisbane, California facility, consisting of approximately 27,000 square feet, to Zymergen, Inc., through August 31, 2022. The base sublease rent rate is $3.53 per rental square foot per month and will increase by 3% on March 1, 2022 through expiration of the agreement. Additionally, the subtenant is required to pay approximately 41% of operating expenses and property management fees that the Company is required to pay under the lease for the Brisbane, California facility. In May 2021, the Company entered into an agreement to sublease the second floor of the Brisbane, California facility, consisting of approximately 11,500 square feet, to CareDx, Inc., through September 30, 2022. The base sublease rent rate is $1.00 per rental square foot per month through expiration of the agreement. Additionally, the subtenant is required to pay approximately 30% of operating expenses and property management fees that the Company is required to pay under the lease for the Brisbane, California facility. The Company incurred initial direct costs of $0.1 million in sublease commissions related to entering into the agreements to sublease the Brisbane, California facility. To account for the commissions, the Company capitalized the total commissions amount and will amortize the balance over the term of the sublease. Sublease income was $0.5 million and $0.1 million for the three months ended March 31, 2022 and 2021, respectively.

In June 2021, the Company entered into an agreement to sublease a portion of the first floor of the South San Francisco, California facility, consisting of approximately 23,000 square feet, to Freenome Holdings, Inc., through

August 31, 2024. The base sublease rent rate is $6.25 per rental square foot per month and will increase annually by 3.5% through expiration of the agreement. Additionally, the subtenant is required to pay approximately 37% of operating expenses and property management fees that the Company is required to pay under the lease for the South San Francisco, California facility. No impairment loss was recorded during the three months ended March 31, 2022. Sublease income was $0.6 million and zero for the three months ended March 31, 2022 and 2021, respectively.

Indemnifications

The Company indemnifies each of its officers and directors for certain events or occurrences, subject to certain limits, while the officer or director is or was serving at the Company’s request in such capacity, as permitted under Delaware law and in accordance with the Company’s amended and restated certificate of incorporation and bylaws. The term of the indemnification period lasts as long as an officer or director may be subject to any proceeding arising out of acts or omissions of such officer or director in such capacity.

The maximum amount of potential future indemnification is unlimited; however, the Company currently holds director and officer liability insurance. This insurance allows the transfer of risk associated with the Company’s exposure and may enable the Company to recover a portion of any future amounts paid. The Company believes that the fair value of these potential indemnification obligations is minimal. Accordingly, the Company has not recognized any liabilities relating to these obligations for any period presented.

Net Loss per Common Share - Schedule of Reconciliation of Numerators and Denominators Used In Computing Net Loss From Continuing Operations Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Numerator:
Net loss	$ (18,915)	$ (15,756)
Denominator:
Weighted-average number of shares outstanding—basic and diluted	67,528,552	54,169,349
Net loss per share, basic and diluted	$ (0.28)	$ (0.29)

- Definition

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

+ References

+ Details

Commitments and Contingencies (Tables)

3 Months Ended

Mar. 31, 2022

Commitments And Contingencies Disclosure [Abstract]

Summary of Components of Lease Expense

The following table summarizes the components of lease expense, which are included in operating expenses in the Company’s condensed statements of operations and comprehensive loss (in thousands):

	Three Months Ended March 31,
	2022			2021
Operating lease cost	$	1,078		$	1,096
Variable lease cost		296			466
Sublease income		(1,048	)		(145	)
Total lease cost	$	326		$	1,417

Summary of Supplemental Information Related to Leases

The following table summarizes supplemental information related to leases (in thousands):

	Three Months Ended March 31,
	2022			2021
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows from operating leases	$	1,704		$	1,652
Weighted-average remaining lease term (years)
Operating leases		7.8			8.3
Weighted-average discount rate (percentage)
Operating leases		6.0	%		5.9	%

Summary of Maturities of Lease Liabilities

The following table summarizes the maturities of lease liabilities as of March 31, 2022 (in thousands):

	Amount
2022 (remaining 9 months)	$	4,579
2023		4,810
2024		4,964
2025		5,123
2026		5,287
Thereafter		16,893
Total future minimum lease payments		41,656
Less: Amount representing interest		(8,391	)
Present value of future minimum lease payments		33,265
Less: Current portion of operating lease liability		(3,926	)
Noncurrent portion of operating lease liability	$	29,339

Organization

3 Months Ended

Mar. 31, 2022

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Organization

1. Organization

Description of Business

Unity Biotechnology, Inc. (the “Company”) is a biotechnology company engaged in the research and development of therapeutics to slow, halt, or reverse diseases of aging. The Company devotes substantially all of its time and efforts to performing research and development, raising capital, and recruiting personnel. The Company’s headquarters are located in South San Francisco, California. The Company was incorporated in the State of Delaware in 2009.

Liquidity

In accordance with Accounting Standards Update (“ASU”) No. 2014-15, Disclosures of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205-40) (“ASU No. 2014-15”), management must evaluate whether there are conditions or events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. This evaluation initially does not take into consideration the potential mitigating effect of management’s plans that have not been fully implemented as of the date the financial statements are issued. When substantial doubt exists under this methodology, management evaluates whether the mitigating effect of its plans sufficiently alleviates substantial doubt about the Company’s ability to continue as a going concern. The mitigating effect of management’s plans, however, is only considered if both (1) it is probable that the plans will be effectively implemented within one year after the date that the financial statements are issued and (2) it is probable that the plans, when implemented, will mitigate the relevant conditions or events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the date that the financial statements are issued. Generally, to be considered probable of being effectively implemented, the plans must have been approved before the date that the financial statements are issued.

The Company’s Condensed Financial Statements have been prepared on a going concern basis, which contemplates the continuity of operations, realization of assets and the satisfaction of liabilities and commitments in the ordinary course of business. The Company has incurred operating losses and has an accumulated deficit as a result of ongoing efforts to develop drug product candidates, including conducting preclinical and clinical trials and providing general and administrative support for these operations. The Company had an accumulated deficit of $418.9 million and $400.0 million as of March 31, 2022 and December 31, 2021, respectively. The Company had net losses of $18.9 million and $15.8 million for the three months ended March 31, 2022 and 2021, respectively, and net cash used in operating activities of $15.0 million and $15.1 million for the three months ended March 31, 2022 and 2021, respectively. To date, none of the Company’s drug candidates have been approved for sale, and therefore, the Company has not generated any product revenue and does not expect positive cash flows from operations in the foreseeable future. The Company has financed its operations primarily through private placements of preferred stock and promissory notes, public equity issuances and more recently, from its ATM Offering Programs (as defined in Note 9), the Term Loan Facility (as defined in Note 7), and an Equity Purchase Agreement (as defined in Note 9) and will continue to be dependent upon equity and/or debt financing until the Company is able to generate positive cash flows from its operations.

The Company had cash, cash equivalents, and marketable securities of $79.2 million as of March 31, 2022. As of May 10, 2022, the date of issuance of these Condensed Financial Statements, the Company expects that its cash and cash equivalents as of March 31, 2022 will not be sufficient to fund its current business plan including related operating expenses and capital expenditure requirements through at least 12 months from the date of issuance of these Condensed Financial Statements. These conditions raise substantial doubt about the Company’s ability to continue as a going concern. The Company plans to seek to address this condition by raising additional capital to finance its operations. The future viability of the Company is dependent on its ability to raise additional capital to finance its operations. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing. Therefore, it is not considered probable, as defined in ASU No. 2014-15, that the Company’s plans to raise additional capital will alleviate the substantial doubt regarding its ability to continue as a going concern.

Management expects operating losses to continue for the foreseeable future. As a result, the Company will need to raise additional capital. If sufficient funds on acceptable terms are not available when needed, the Company could be required to significantly reduce its operating expenses and delay, reduce the scope of, or eliminate one or more of its development programs. Failure to manage discretionary spending or raise additional financing, as needed, may adversely impact the Company’s ability to achieve its intended business objectives.

Related Party Transactions

3 Months Ended

Mar. 31, 2022

Related-Party Transactions

8. Related Party Transactions

Licensing Revenue – Related Party

In December 2021, the Company entered into a license agreement with Jocasta Neuroscience, Inc. A member of the Board of Directors of the Company is also an affiliate of Jocasta Neuroscience, Inc. The agreement provides for an upfront fee of $5.0 million and the opportunity for future research and development services to be provided. The Company recognized $4.8 million of licensing revenue for the year ended December 31, 2021. No licensing revenue was recognized for the three months ended March 31, 2022 and 2021.

Recourse Notes

In January 2018, the Company issued full-recourse promissory notes to a non-executive officer employee of the Company for an aggregate principal amount of $0.2 million with an interest rate of 2.5% per annum. All of the principal was used to early exercise options for 59,322 shares of the Company’s common stock. In December 2019, the full recourse note was deemed satisfied and superseded by a new full recourse promissory note agreement with a principal amount of $0.2 million and an interest rate of 1.51% per annum. In January 2021, the non-executive officer employee terminated his employment with the Company. As at March 31, 2021 the Company reclassified the $0.2 million recorded on the balance sheet in stockholders’ equity as ‘Related party promissory note for purchase of common stock’ to ‘Promissory notes for purchase of common stock’. The balance was repaid in full during the three months ended June 30, 2021.

Defined Contribution Plan - Additional Information (Details) - Defined Contribution Plan - USD ($) $ in Millions	1 Months Ended	3 Months Ended
	Jan. 31, 2019	Mar. 31, 2022	Mar. 31, 2021
Defined Contribution Plan Disclosure [Line Items]
Percent of employer matching contribution of employees' salary	4.00%
Defined Contribution Plan, Sponsor Location [Extensible Enumeration]	us-gaap:DomesticPlanMember
Matching contributions		$ 0.2	$ 0.2

Corporate Restructuring

3 Months Ended

Mar. 31, 2022

Restructuring And Related Activities [Abstract]

Corporate Restructuring

10. Corporate Restructuring

In February 2022, the Company implemented a corporate restructuring to align its resources to focus on its UBX1325 program while further extending operating capital. The restructuring is expected to result in an elimination of approximately 32 positions, or approximately 50% of the Company’s workforce, by the first half of 2022. The Company will incur a one-time employee benefits and severance charge of approximately $2.0 million in operating expenses in the first half of 2022. The related accrual is recorded in accrued compensation on the condensed balance sheet at March 31, 2022. Restructuring charges incurred under this plan primarily consisted of employee termination benefits. Employee termination benefits include $1.7 million of severance costs, $0.2 million of employee-related benefits, $0.1 million of payroll taxes and supplemental one-time termination payments. Charges and other costs related to the workforce reduction and structure realignment, and non-cash share-based compensation credits related to the forfeiture of stock options for $0.3 million are included in operating expenses in the condensed statements of operations and comprehensive loss. Of the total charge, $1.2 million was recorded to research and development expenses and $0.4 million was recorded to general and administrative expenses during the quarter ended March 31, 2022. The Company may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the restructuring. The Company may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the restructuring.

License Revenue and Agreements

3 Months Ended

Mar. 31, 2022

Research And Development [Abstract]

License Revenue and Agreements

5. License Revenue and Agreements

The Company has entered into license agreements with other pharmaceutical and biotechnology companies. The Company’s accounts receivable balances may contain billed and unbilled amounts from milestones and other contingent payments. The Company performs a regular review of its customers’ credit risk and payment histories, including payments made after period end. Historically, the Company has not experienced credit loss from its accounts receivable and, therefore, has not recorded a reserve for estimated credit losses as of March 31, 2022 and December 31, 2021.

License Agreement with Jocasta Neuroscience, Inc.

In December 2021, the Company signed a License Agreement with Jocasta Neuroscience, Inc. (“the Jocasta Agreement”) to exclusively license its rights in the α-Klotho asset for development and commercialization, and included a sublicense agreement under the original license agreement with the University of California, San Francisco. Under the Jocasta Agreement, the Company received a $5.0 million upfront cash payment from Jocasta Neuroscience, Inc. The Company may also receive additional payments based on development milestones, approval milestones, and sales-based royalties, per indication. The Jocasta agreement is recognized in accordance with ASC 606, Revenue from Contracts with Customers, and is classified under License Revenue.

Promises that the Company concluded were distinct performance obligations in the License Agreement included: (1) the license of intellectual property and delivery of know-how, and (2) the transfer of licensed compounds and materials.

In order to determine the transaction price, the Company evaluated all the payments to be received during the duration of the contract. Fixed consideration exists in the form of the upfront payment. Regulatory milestones and royalties were considered variable consideration. The estimated variable consideration is constrained until the Company determines it is probable that a significant reversal in the amount of cumulative revenue recognized will not occur in future periods. Milestone payments are constrained and not included in the transaction price due to the uncertainties of research and development. The Company will re-evaluate the transaction price, including the estimated variable consideration included in the transaction price and all constrained amounts, in each reporting period and as uncertain events are resolved or other changes in circumstances occur. The Company determined that the initial transaction price consists of the upfront payment of $5.0 million. The allocation of the transaction price is performed based on standalone selling prices, which are based on estimated amounts that the Company would charge for a performance obligation if it were sold separately. The transaction price allocated to the license of intellectual property and delivery of know-how was recognized upon grant of license and delivery of know-how. The transaction price allocated the transfer of licensed compounds and materials, will be recognized over time as the materials are delivered. Consideration received in advance are recorded as deferred revenue and will be recognized as the performance obligations are satisfied.

For the three months ended March 31, 2022 and 2021, the Company did not recognize any license revenue or any deferred revenue related to the Jocasta Agreement. The deferred revenue balance was $0.2 million as of March 31, 2022 and December 31, 2021.

License Agreements with Research Institutions

In May 2019, the Company entered into a license agreement with The Regents of the University of California on behalf its San Francisco campus (collectively, “UCSF”) which provides the Company the rights to certain patents and related know-how to make, use, sell, offer for sale and import certain products and practice certain methods for use in the development of human therapeutics, which excludes the provision of services to third parties for consideration of any kind. The license to the Company is subject to UCSF’s reserved rights under the licensed intellectual property for educational and non-commercial research purposes and a requirement to substantially manufacture any licensed products in the United States. The Company is obligated to use diligent efforts to develop and obtain regulatory approval for at least one product commercialized pursuant to the agreement, and must meet certain regulatory and development milestones. In June 2019, as part of this license agreement, the Company issued 120,000 shares of its common stock to UCSF. In addition, the Company is obligated to pay an annual license

maintenance fee and may be obligated to make milestone payments or issue up to an additional 34,000 shares of its common stock upon the occurrence of specified development events, up to aggregate milestone payments of $13.6 million for each product licensed under the agreement, and upon commercialization, to make royalty payments in the low single digit percentages (subject to a specified minimum annual royalty) based on net sales of products commercialized pursuant to the agreement. None of these events had occurred and no milestone payments or royalty payments had been recognized as of March 31, 2022. The upfront issuance of 120,000 shares of the Company’s common stock was valued at $1.0 million and recorded as additional paid-in capital upon issuance in June 2019. In December 2021, the Company entered an agreement to exclusively license its rights in the α-Klotho asset to Jocasta Neuroscience, Inc. for development and commercialization. Under the license agreement, Jocasta Neuroscience, Inc. is, in addition to the payments due to the Company, required to make all payments due to UCSF from the Company under the UCSF License. See above, “License Agreement with Jocasta Neuroscience, Inc.” for additional information on the Jocasta Agreement.

The Company has also entered into license agreements with various research institutions which have provided the Company with rights to patents, and in certain cases, research “know-how” and proprietary research tools to research, develop and commercialize drug candidates. In addition to upfront consideration paid to these various research institutions in either cash or shares of the Company’s common stock, the Company may be obligated to make milestone payments, payable in cash and/or the issuance of shares of the Company’s common stock upon achievement of certain specified clinical development and/or sales events. There was no contingent consideration liability considered to be a derivative associated with the potential issuance of common stock related to these license agreements at March 31, 2022 and December 31, 2021. To date, none of these events has occurred and no contingent consideration, milestone or royalty payments have been recognized.

License and Compound Library and Option Agreement

The Company is a party to three agreements, two active and one terminated, with Ascentage Pharma: (a) a compound library and option agreement executed in February 2016 granting the Company the right to identify and take licenses to research, develop, and seek and obtain marketing approval for library compounds for the treatment of indications outside of oncology (the “Library Agreement”), (b) an initial license agreement executed in February 2016 granting the Company rights to an initial Ascentage Pharma compound known as APG1252 (the “APG1252 License Agreement”), and (c) a second license agreement executed in January 2019 granting the Company rights to a second licensed compound (this second license agreement, the “Bcl License Agreement” and collectively with the Library Agreement and APG1252 License Agreement, the “Commercial Agreements”). On July 30, 2020, the Company notified Ascentage Pharma of its termination of the APG1252 License Agreement due to the Company’s decision to prioritize the progression of other compounds from Ascentage International’s library of Bcl-2 inhibitors, such as UBX1325, a Bcl-xL inhibitor.

The Commercial Agreements referenced above include cash payments of up to $70.3 million as well as the equity payments of up to an aggregate of (a) 933,337 shares of common stock in the event there is only one licensed product, and (b) 1,333,338 shares of common stock in the event there are two or more licensed products, in each case to be issued based on the Company’s achievement of certain preclinical and clinical development and sales milestone events. The Company is required to make 80% of all equity payments to Ascentage Pharma and the remaining 20% to an academic institution from whom Ascentage Pharma had previously licensed the technology. The milestones include the advancement of additional compounds into Investigational New Drug application (“IND”) enabling studies, the filing of an IND, the commencement of clinical studies, Food and Drug Administration (“FDA”) and/or European Medicines Agency approval, and a net sales threshold. The Bcl License Agreement also includes tiered royalties in the low-single digits based on sales of licensed products.

As of March 31, 2022, pursuant to these agreements, the Company had issued 1,269,755 shares of common stock to Ascentage Pharma and 291,944 shares of common stock to the academic institution from whom Ascentage Pharma had previously licensed the technology. In May 2021, the Company initiated a Phase 2 proof-of-concept study of UBX1325 in patients with diabetic macular edema. As a result of the first patient dosed in the Phase 2 proof-of-concept UBX1325 study in June 2021, the Company triggered a milestone payment of $2.0 million for Ascentage Pharma, which the Company elected to settle in shares of the Company’s common stock. At the instruction of Ascentage Pharma, the Company issued 294,775 shares of its common stock to Ascentage Pharma as of August 2021 with a fair market value of $1.1 million net of withholding taxes, and 105,277 shares of its common stock to the academic institution with a fair market value of $0.4 million at settlement date. The milestone payment was recognized as research and development expense in the statement of operations and comprehensive loss during the

year ended December 31, 2021. The Company had previously issued 361,664 shares of its common stock with a value of $2.3 million to Ascentage Pharma as of December 31, 2020.

The Commercial Agreements included contingent consideration in the form of additional issuances of shares of the Company’s common stock based on the achievement of the specified milestones. Upon the July 2020 termination of the license to APG1252, the Company determined that the contingency no longer applied and adjusted the fair value of the contingent consideration liability to zero. To date, no royalties were due from the sales of licensed products.

Net Loss per Common Share - Additional Information (Details)	3 Months Ended
	Mar. 31, 2022 shares
Maximum
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Shares contingently issued	55,900

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended				3 Months Ended
	Feb. 28, 2022	Jun. 30, 2021	Jan. 31, 2021	Mar. 31, 2020	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares options granted to purchase an aggregate of common stock					1,897,085
Compensation cost recognized				$ 200,000
Stock option awards outstanding					9,846,774		8,666,955
Stock based compensation expense for liability awards					$ 0	$ 0
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of retention awards granted	1,893,335
Retention award grant date total fair value	$ 2,000,000.0
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of retention awards granted	463,328
Retention award grant date total fair value	$ 500,000
Performance and Market Contingent Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Trailing period		30 days
Modification date fair value		$ 102,000	$ 81,000
Implied service period for recognition		1 year 10 months 6 days
Stock option awards outstanding					50,849
Performance and Market Contingent Stock Options \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Implied service period for recognition			1 year 5 months 15 days
Attaining valuation of certain amount		$ 1,000,000,000
Performance and Market Contingent Stock Options \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Implied service period for recognition			2 years 6 months 7 days
Performance and Market Contingent Stock Options \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volume-weighted average per Share closing trading price			$ 18.00
Trailing period			30 days
Performance and Market Contingent Stock Options \| Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volume-weighted average per Share closing trading price			$ 36.00
Trailing period			30 days
Performance and Market Contingent Stock Options \| Executive Team
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option awards exercisable upon the achievement of performance goals		33,370	17,479
2020 Employment Inducement Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental fair value on modification date			$ 31,000
Unamortized value of original grant			$ 569,000
2020 Employment Inducement Incentive Plan \| New Chief Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares granted				1,100,000
2020 Employment Inducement Incentive Plan \| Stock Options \| New Chief Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares options granted to purchase an aggregate of common stock				800,000
2020 Employment Inducement Incentive Plan \| PSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Grant date fair value				$ 700,000
Weighted-average derived service period for recognition				4 years 3 months 18 days
2020 Employment Inducement Incentive Plan \| PSUs \| Minimum [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
New implied service period for recognition				1 year 7 months 17 days
2020 Employment Inducement Incentive Plan \| PSUs \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
New implied service period for recognition				2 years 9 months 14 days
2020 Employment Inducement Incentive Plan \| PSUs \| Tranche One
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares to vest upon attainment of certain conditions			50,000	50,000
Volume-weighted average per Share closing trading price			$ 18	$ 36.875
Trailing period			30 days	30 days
2020 Employment Inducement Incentive Plan \| PSUs \| Tranche Two
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares to vest upon attainment of certain conditions			100,000	100,000
Trailing period			30 days	30 days
Price per share to holders of company's common stock			$ 36.00	$ 36.875
Market capitalization trigger				$ 2,500,000,000
2020 Employment Inducement Incentive Plan \| PSUs \| New Chief Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares options granted to purchase an aggregate of common stock				150,000
2020 Employment Inducement Incentive Plan \| RSUs and Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting rights				The stock options and RSUs will vest subject to continued service through the applicable vesting date.
2020 Employment Inducement Incentive Plan \| RSUs \| New Chief Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares granted				120,000
2020 Employment Inducement Incentive Plan \| Common Stock
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares vested				30,000
2020 Employment Inducement Incentive Plan \| Common Stock \| New Chief Executive Officer
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of common stock shares granted				30,000

Term Loan Facility (Tables)

3 Months Ended

Mar. 31, 2022

Debt Disclosure [Abstract]

Schedule of Future Principal Payments for Long-Term Debt

Future principal payments for the long-term debt as of March 31, 2022 are as follows (in thousands):

	Amount
2022 (for the remaining 9 months)	$	3,063
2023		9,813
2024		7,124
Total principal payments		20,000
End of term fee due at maturity in 2024		1,563
Total principal and end of term fee payments		21,563
Unamortized discount and debt issuance costs		(2,192	)
Present value of remaining debt payments		19,371
Current portion of long-term debt		(4,837	)
Long-term debt, net	$	14,534

Defined Contribution Plan

3 Months Ended

Mar. 31, 2022

Compensation And Retirement Disclosure [Abstract]

Defined Contribution Plan

13. Defined Contribution Plan

The Company sponsors a 401(k) Plan that stipulates that eligible employees can elect to contribute to the 401(k) Plan, subject to certain limitations, on a pretax basis. In January 2019, the Company began to match 4% of employees’ salary. During the three months ended March 31, 2022 and 2021, the Company recorded matching contributions of $0.2 million and $0.2 million, respectively.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (o)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (p)
-URI http://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 70
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-Paragraph 1
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+ Details

Fair Value Measurements - Summary of Reconciliation of Derivative Liability Related to Debt Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Details) - Fair Value, Recurring - Level 3 - Derivative Liability Related To Debt Conversion Feature
$ in Thousands

3 Months Ended

Mar. 31, 2022

USD ($)

^[1]

Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]

Balance at December 31, 2021

$ 963

Conversion

(963)

Balance at March 31, 2022

$ 0

[1]	Transfers into Level 3 during the year ended December 31, 2021 relate to the call option with Hercules Capital, Inc, where the lender can convert principal debt into common stock. Transfers out of Level 3 during the year relate to the conversions calls of this option made by Hercules Capital, Inc.

Equity Financing - Additional Information (Details) - USD ($)		1 Months Ended				3 Months Ended		12 Months Ended
	Sep. 29, 2021	Mar. 31, 2022	Dec. 31, 2021	Jul. 31, 2020	Jun. 30, 2019	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount					$ 250,000,000.0
At The Market Equity Offering Program
Subsidiary Sale Of Stock [Line Items]
Proceeds from sale of common stock						$ 3,420,000	$ 8,892,000
Issuance of common stock, value						$ 3,420,000	$ 8,892,000
At The Market Equity Offering Program \| Cowen \| June 2019 Sales Agreement
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)									5,002,257
Proceeds from sale of common stock									$ 37,300,000
Payments for other offering expenses									$ 1,300,000
At The Market Equity Offering Program \| Cowen \| June 2019 Sales Agreement \| Maximum
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount					$ 75,000,000.0
Percentage of gross sales proceeds of common stock payable as compensation					3.00%
At The Market Equity Offering Program \| Cowen \| July 2020 Sales Agreement
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)						2,325,000
Proceeds from sale of common stock						$ 3,400,000
Payments for other offering expenses						$ 100,000
At The Market Equity Offering Program \| Cowen \| July 2020 Sales Agreement \| Maximum
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount				$ 50,000,000.0
Percentage of gross sales proceeds of common stock payable as compensation				3.00%
At The Market Equity Offering Program \| Cowen \| March 2022 Sales Agreement \| Maximum
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount		$ 50,000,000.0
At The Market Equity Offering Program \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount					$ 75,000,000.0
Issuance of common stock (in shares)						2,325,000	1,220,629
At The Market Equity Offering Program \| Common Stock \| March 2022 Sales Agreement
Subsidiary Sale Of Stock [Line Items]
Equity financing, authorized amount		$ 50,000,000.0
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)	1,020,408		2,900,000			900,000
Issuance of common stock, value						$ 910,000
Purchase agreement term	36 months
Share purchase price	$ 2.94
Total gross purchase price of share	$ 3,000,000.0
Regular purchase capped amount	$ 2,000,000
Percentage of trading volume	30.00%
Percentage of purchase price	97.00%
Percentage of shares issued to common shares outstanding immediately prior to the execution of the purchase agreement.	19.99%
Purchase agreement price per share	$ 2.94
Maximum percentage ownership of issued and outstanding shares	9.99%
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Purchase Agreement 3.50 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount closing price per share	$ 3.50
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Purchase Agreement 5.00 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount closing price per share	5.00
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Purchase Agreement 7.00 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount closing price per share	$ 7.00
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Maximum
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)	11,065,803
Issuance of common stock, value	$ 30,000,000
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Maximum \| Purchase Agreement 3.50 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount shares	150,000
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Maximum \| Purchase Agreement 5.00 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount shares	200,000
Equity Purchase Agreement \| Lincoln Park Capital Fund LLC \| Maximum \| Purchase Agreement 7.00 Closing Price
Subsidiary Sale Of Stock [Line Items]
Regular purchase amount shares	250,000
Equity Purchase Agreement \| Common Stock \| Lincoln Park Capital Fund LLC
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)	252,447					900,000
Proceeds from sale of common stock						$ 900,000		$ 5,300,000
Other expense related to the commitment shares issued to Lincoln Park Capital Fund	$ 800,000
Equity Purchase Agreement \| Common Stock \| Lincoln Park Capital Fund LLC \| Regular Purchase Amount per Business Day \| Maximum
Subsidiary Sale Of Stock [Line Items]
Issuance of common stock (in shares)	100,000

Fair Value Measurements

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements

•

Level 1: Quoted prices in active markets for identical instruments

•

Level 2: Other significant observable inputs (including quoted prices in active markets for similar instruments)

•

Level 3: Significant unobservable inputs (including assumptions in determining the fair value of certain investments)

The carrying amounts of financial instruments such as cash and cash equivalents, restricted cash, prepaid expenses and other current assets, accounts payable, accrued compensation, accrued and other current liabilities approximate

the related fair values due to the short maturities of these instruments. As the long-term debt is subject to variable interest rates that are based on market rates which are regularly reset, considering level 2 inputs, the Company believes the carrying value of the long-term debt approximates its fair value.

The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements were as follows (in thousands):

	March 31, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	9,766	$	9,766	$	—	$	—
U.S. treasuries		2,000		—		2,000		—
Total cash equivalents		11,766		9,766		2,000		—
Short-term marketable securities:
U.S. treasuries		59,709		—		59,709		—
U.S. government debt securities		3,008		—		3,008		—
Total short-term marketable securities		62,717		—		62,717		—
Total assets subject to fair value measurements on a recurring basis	$	74,483	$	9,766	$	64,717	$	—

	December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	21,421	$	21,421	$	—	$	—
Total cash equivalents		21,421		21,421		—		—
Short-term marketable securities:
U.S. treasuries		52,146		—		52,146		—
U.S. government debt securities		3,024		—		3,024		—
Total short-term marketable securities		55,170		—		55,170		—
Long-term marketable securities:
U.S. treasuries		1,993		—		1,993		—
Total long-term marketable securities		1,993		—		1,993		—
Total assets subject to fair value measurements on a recurring basis	$	78,584	$	21,421	$	57,163	$	—

In December 2021, the Company recorded a derivative liability relating to an amendment to its loan and security agreement. It comprised of a redemption conversion feature which met the definition of a derivative instrument, which terms are included in the amended loan and security agreement. See Note 7, “Term Loan Facility”. The Company classified this instrument as a liability on the balance sheet because the feature was not clearly and closely related to its host instrument and met the definition of a derivative. The derivative liability was initially recorded at fair value upon issuance of the loan amendment and is being subsequently remeasured to fair value at each reporting date. Changes in the fair value of the derivative liability are recognized as a component of other income (expense), net in the statements of operations.

The following table provides a reconciliation of the derivative liability related to debt measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands):

	Derivative Liability related to Debt Conversion Feature⁽¹⁾
Balance at December 31, 2021	$	963
Additions		—
Conversion		(963	)
Change in fair value		—
Balance at March 31, 2022	$	—

⁽¹⁾	Transfers into Level 3 during the year ended December 31, 2021 relate to the call option with Hercules Capital, Inc, where the lender can convert principal debt into common stock. Transfers out of Level 3 during the year relate to the conversions calls of this option made by Hercules Capital, Inc.

- 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

Condensed Statements of Operations and Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Operating expenses:
Research and development	$ 12,461	$ 8,717
General and administrative	5,806	6,226
Total operating expenses	18,267	14,943
Loss from operations	(18,267)	(14,943)
Interest income	29	36
Interest expense	(808)	(775)
Other income (expense), net	131	(74)
Net loss	(18,915)	(15,756)
Other comprehensive (loss) gain
Unrealized (loss) gain on marketable debt securities	(132)	10
Comprehensive loss	$ (19,047)	$ (15,746)
Net loss per share, basic and diluted	$ (0.28)	$ (0.29)
Weighted-average number of shares used in computing net loss per share, basic and diluted	67,528,552	54,169,349

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2022

Fair Value Disclosures [Abstract]

Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis and Level of Inputs Used in Measurements

The Company’s financial assets and liabilities subject to fair value measurements on a recurring basis and the level of inputs used in such measurements were as follows (in thousands):

	March 31, 2022
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	9,766	$	9,766	$	—	$	—
U.S. treasuries		2,000		—		2,000		—
Total cash equivalents		11,766		9,766		2,000		—
Short-term marketable securities:
U.S. treasuries		59,709		—		59,709		—
U.S. government debt securities		3,008		—		3,008		—
Total short-term marketable securities		62,717		—		62,717		—
Total assets subject to fair value measurements on a recurring basis	$	74,483	$	9,766	$	64,717	$	—

	December 31, 2021
	Total		Level 1		Level 2		Level 3
Assets:
Cash equivalents:
Money market funds	$	21,421	$	21,421	$	—	$	—
Total cash equivalents		21,421		21,421		—		—
Short-term marketable securities:
U.S. treasuries		52,146		—		52,146		—
U.S. government debt securities		3,024		—		3,024		—
Total short-term marketable securities		55,170		—		55,170		—
Long-term marketable securities:
U.S. treasuries		1,993		—		1,993		—
Total long-term marketable securities		1,993		—		1,993		—
Total assets subject to fair value measurements on a recurring basis	$	78,584	$	21,421	$	57,163	$	—

Summary of Reconciliation of Derivative Liability Related to Debt Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs

The following table provides a reconciliation of the derivative liability related to debt measured at fair value on a recurring basis using significant unobservable inputs (Level 3) (in thousands):

	Derivative Liability related to Debt Conversion Feature⁽¹⁾
Balance at December 31, 2021	$	963
Additions		—
Conversion		(963	)
Change in fair value		—
Balance at March 31, 2022	$	—

License Revenue and Agreements - Additional Information (Details) - USD ($)

1 Months Ended

3 Months Ended

12 Months Ended

Jun. 30, 2021

Jun. 30, 2019

Mar. 31, 2022

Mar. 31, 2021

Dec. 31, 2021

Aug. 31, 2021

Dec. 31, 2020

Research And Development Arrangement Contract To Perform For Others [Line Items]

Compound library and option agreement execution month and year

2016-02

Common stock, shares issued

69,148,106

62,991,906

Common stock, value

$ 7,000

$ 6,000

^[1]

Licensed Products

Research And Development Arrangement Contract To Perform For Others [Line Items]

Royalties due from sales

License Agreement | Jocasta Neuroscience Inc

Research And Development Arrangement Contract To Perform For Others [Line Items]

Upfront cash payments received

5,000,000.0

Revenue recognized

$ 0

Deferred revenue recognized

$ 0

Deferred revenue

200,000

Other Licensing Agreements with Research Institutions

Research And Development Arrangement Contract To Perform For Others [Line Items]

Common shares expected to be issued

34,000

Contingent consideration, milestone or royalty payments

$ 0

Maximum milestone payments for each product licensed under agreement

$ 13,600,000

Other Licensing Agreements with Research Institutions | Common Stock

Research And Development Arrangement Contract To Perform For Others [Line Items]

Issuance of common stock (in shares)

120,000

Other Licensing Agreements with Research Institutions | Additional Paid-In Capital

Research And Development Arrangement Contract To Perform For Others [Line Items]

Issuance of common stock, net of issuance costs

$ 1,000,000.0

Commercial Agreements

Research And Development Arrangement Contract To Perform For Others [Line Items]

Milestone payments

$ 2,000,000.0

Equity payments percentage

20.00%

Common stock, shares issued

291,944

105,277

361,664

Common stock fair market value, net of withholding taxes

$ 1,100,000

Common stock fair market value

$ 400,000

Common stock, value

$ 2,300,000

Contingent consideration liability

$ 0

Commercial Agreements | Maximum

Research And Development Arrangement Contract To Perform For Others [Line Items]

Contingent consideration additional common stock issued for one licensed product

933,337

Contingent consideration additional common stock issued for two or more licensed product

1,333,338

Milestone payments

$ 70,300,000

Commercial Agreements | Initial License Agreement

Research And Development Arrangement Contract To Perform For Others [Line Items]

License agreement execution month and year

2016-02

Commercial Agreements | Second License Agreement

Research And Development Arrangement Contract To Perform For Others [Line Items]

License agreement execution month and year

2019-01

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Commitments and Contingencies - Summary of Maturities of Lease Liabilities (Details) - USD ($)
$ in Thousands

Mar. 31, 2022

Dec. 31, 2021

^[1]

Commitments And Contingencies Disclosure [Abstract]

2022 (remaining 9 months)

$ 4,579

4,810

4,964

5,123

5,287

16,893

Total future minimum lease payments

41,656

Less: Amount representing interest

(8,391)

Present value of future minimum lease payments

33,265

Less: Current portion of operating lease liability

(3,926)

Noncurrent portion of operating lease liability

$ 29,339

$ 30,094

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Corporate Restructuring - Additional Information (Details) $ in Millions	1 Months Ended	3 Months Ended	6 Months Ended
	Feb. 28, 2022 Position	Mar. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)
Restructuring Cost And Reserve [Line Items]
Restructuring implementation date	2022-02
Number of positions eliminated \| Position	32
Percentage of positions eliminated	50.00%
Non-cash share-based payment compensation credits to forfeiture of stock options		$ 0.3
Research And Development Expense
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses		1.2
General And Administrative Expense
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses		0.4
Employee Termination Benefits
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses		1.7
Employee Termination Benefits \| Employee-Related Benefits
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses		0.2
Employee Termination Benefits \| Payroll Taxes
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses		$ 0.1
Scenario Forecast
Restructuring Cost And Reserve [Line Items]
Severance charge in operating expenses			$ 2.0

Term Loan Facility - Additional Information (Details) $ in Thousands				3 Months Ended		12 Months Ended
	Mar. 17, 2022	Dec. 15, 2021 USD ($)	Aug. 03, 2020 USD ($) Tranche	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)	Jul. 01, 2021 USD ($)
Debt Instrument [Line Items]
Debt instrument aggregate principal amount				$ 20,000
Unamortized discount and debt issuance costs				2,192
End of term fee due at maturity				1,563
Interest expense				808	$ 775
Term Loan \| Loan Agreement
Debt Instrument [Line Items]
Debt conversion, original debt amount						$ 2,300
Loan issuance cost						$ 100
Term Loan \| Loan Agreement \| Maximum
Debt Instrument [Line Items]
Loan amendment conversion effective month of anniversary		6 months
Debt conversion percentage of principal amount		20.00%
Debt conversion, original debt amount		$ 5,000
Term Loan \| Loan Agreement \| Hercules Capital
Debt Instrument [Line Items]
Debt instrument aggregate principal amount				20,000
Number of tranches \| Tranche			4
Principal amount of first tranche			$ 25,000	20,000
Debt conversion, original debt amount				$ 2,700
Long-term debt, maturity date				Aug. 01, 2024
Final payment fee of the total term loan advanced				6.25%
Debt instrument, interest rate terms				Interest on the term loan accrues at a per annum rate equal to the greater of (i) the Wall Street Journal prime rate plus 6.10% and (ii) 9.35%. On March 17, 2022, the prime rate was raised to 3.50%. On March 31, 2022, the interest rate on the term loan was 9.60%. Interest expense is calculated using the effective interest method and is inclusive of non-cash amortization of capitalized loan issuance costs. At March 31, 2022, the effective interest rate was 17.26%.
Debt instrument, interest rate, stated percentage				9.60%
Debt instrument, interest rate, effective percentage				17.26%
Maximum amount of debt that can be purchased by lender.				$ 2,000
Debt instrument, minimum unrestricted cash							$ 15,000
Unamortized discount and debt issuance costs				2,200
End of term fee due at maturity				1,600
Term Loan \| Loan Agreement \| Hercules Capital \| Interest And Other Expense
Debt Instrument [Line Items]
Interest expense				$ 800	$ 800
Term Loan \| Loan Agreement \| Hercules Capital \| Wall Street Journal Prime Rate
Debt Instrument [Line Items]
Debt instrument, interest rate, basis spread on variable rate				6.10%
Debt instrument, interest rate during period	3.50%
Term Loan \| Loan Agreement \| Hercules Capital \| Maximum
Debt Instrument [Line Items]
Debt instrument aggregate principal amount			$ 80,000
Prepayment fee				1.50%
Term Loan \| Loan Agreement \| Hercules Capital \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument, interest rate, stated percentage				9.35%

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2022

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

Unaudited Condensed Financial Statements

Use of Estimates

Segments

Restructuring

Recently Issued Accounting Pronouncements Not Yet Adopted

Condensed Statements of Stockholders' Equity (Unaudited) - USD ($)
$ in Thousands

Total

At The Market Equity Offering Program

Equity Purchase Agreement

Lincoln Park Capital Fund LLC

Loan Agreement

Hercules Capital

Common Stock

At The Market Equity Offering Program

Common Stock

Equity Purchase Agreement

Lincoln Park Capital Fund LLC

Common Stock

Loan Agreement

Hercules Capital

Additional Paid-In Capital

At The Market Equity Offering Program

Additional Paid-In Capital

Equity Purchase Agreement

Lincoln Park Capital Fund LLC

Additional Paid-In Capital

Loan Agreement

Hercules Capital

Related Party Promissory Notes for Purchase of Common Stock

Employee Promissory Notes for Purchase of Common Stock

Accumulated Other Comprehensive Gain (Loss)

Accumulated Deficit

Beginning balance at Dec. 31, 2020

$ 82,880

$ 5

$ 422,379

$ (210)

$ 5

$ (339,299)

Beginning balance, (in shares) at Dec. 31, 2020

53,253,213

Issuance of common stock, net of issuance costs

$ 8,892

Issuance of common stock (in shares)

1,220,629

Vesting of restricted stock units, (in shares)

88,218

Issuance of common stock upon exercise of stock options

1,183

Issuance of common stock upon exercise of stock options (in shares)

259,019

Repurchase of early exercised shares, (in shares)

(33,370)

Stock-based compensation

2,744

Reclass of promissory notes for purchase ofcommon stock

$ 210

$ (210)

Unrealized (loss) gain on marketable debt securities

Net loss

(15,756)

Ending balance at Mar. 31, 2021

79,953

$ 5

435,198

$ (210)

(355,055)

Ending balance, (in shares) at Mar. 31, 2021

54,787,709

Beginning balance at Dec. 31, 2021

$ 59,569

^[1]

$ 6

459,631

(44)

(400,024)

Beginning balance, (in shares) at Dec. 31, 2021

62,991,906

Issuance of common stock, net of issuance costs

$ 3,420

$ 910

$ 3,179

$ 1

$ 3,420

$ 910

$ 3,178

Issuance of common stock (in shares)

900,000

2,325,000

900,000

2,627,612

Vesting of restricted stock units, (in shares)

303,588

Stock-based compensation

$ 2,660

2,660

Unrealized (loss) gain on marketable debt securities

(132)

Net loss

(18,915)

Ending balance at Mar. 31, 2022

$ 50,691

$ 7

$ 469,799

$ (176)

$ (418,939)

Ending balance, (in shares) at Mar. 31, 2022

69,148,106

[1]	The balance sheet as of December 31, 2021 is derived from the audited financial statements as of that date.

Commitments and Contingencies - Summary of Supplemental Information Related to Leases (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Operating cash flows from operating leases	$ 1,704	$ 1,652
Operating leases, Weighted-average remaining lease term (years)	7 years 9 months 18 days	8 years 3 months 18 days
Operating leases, Weighted-average discount rate (percentage)	6.00%	5.90%

Fair Value Measurements - Summary of Financial Assets and Liabilities Subject to Fair Value Measurements on Recurring Basis and Level of Inputs Used in Measurements (Details) - USD ($)
$ in Thousands

Mar. 31, 2022

Dec. 31, 2021

Assets:

Short-term marketable securities

$ 62,717

$ 55,170

^[1]

Long-term marketable securities

1,993

^[1]

Fair Value, Recurring

Assets: