0000950170-24-057259 | 10-Q | XBRL Viewer

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BALANCE SHEETS (Unaudited) (Parenthetical) - $ / shares	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	20,000,000	20,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	88,544,000	87,750,000
Common stock, shares outstanding	88,544,000	87,750,000

Balance Sheet Components and Supplemental Disclosures

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Components and Supplemental Disclosures

6. Balance Sheet Components and Supplemental Disclosures

Property and Equipment, Net

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


	March 31,			December 31,
	2024			2023
Laboratory equipment	$	6,993		$	6,993
Furniture and office equipment		2,941			3,947
Leasehold improvements		18,454			32,386
Capitalized software		4,382			4,382
Construction-in-progress		73			69
		32,843			47,777
Less accumulated depreciation		(15,479	)		(14,408	)
Property and equipment, net	$	17,364		$	33,369

Depreciation and amortization expense for the three months ended March 31, 2024 and 2023 was $1.1 million and $1.5 million, respectively. As discussed in Note 5 – Impairment of Long-Lived Assets, the Company recognized long-lived asset impairment charges of $13.9 million for its leasehold improvements and $1.0 million on furniture as an adjustment to their gross values during the three months ended March 31, 2024.

Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	March 31,		December 31,
	2024		2023
Accrued contract research and development expense	$	13,213	$	22,262
Accrued compensation and benefits expense		2,894		8,674
Current portion of operating lease liabilities		3,022		3,250
Other current liabilities		1,044		628
Total	$	20,173	$	34,814

Defined Contribution Plans	3 Months Ended
Mar. 31, 2024
Retirement Benefits [Abstract]
Defined Contribution Plans	11. Defined Contribution Plans In January 2018, the Company established a defined contribution plan under Section 401(k) of the Internal Revenue Code (the “401(k) plan”). The 401(k) plan covers all employees who meet defined minimum age and service requirements. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under U.S. federal tax regulations. The Company makes matching contributions of up to 4% of the eligible employees’ compensation to the 401(k) plan. During each of the three months ended March 31, 2024 and 2023, the Company made contributions to the 401(k) plan of $0.5 million.

Defined Contribution Plans

3 Months Ended

Mar. 31, 2024

Retirement Benefits [Abstract]

Defined Contribution Plans

11. Defined Contribution Plans

In January 2018, the Company established a defined contribution plan under Section 401(k) of the Internal Revenue Code (the “401(k) plan”). The 401(k) plan covers all employees who meet defined minimum age and service requirements. Employee contributions are voluntary and are determined on an individual basis, limited to the maximum amount allowable under U.S. federal tax regulations. The Company makes matching contributions of up to 4% of the eligible employees’ compensation to the 401(k) plan. During each of the three months ended March 31, 2024 and 2023, the Company made contributions to the 401(k) plan of $0.5 million.

Summary of Significant Accounting Policies - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Cash and Cash Equivalents [Abstract]
Cash and cash equivalents	$ 43,060	$ 66,440	$ 93,854	$ 87,217
Restricted cash in other long-term assets	1,472	1,472	1,472	1,472
Total	$ 44,532	$ 67,912	$ 95,326	$ 88,689

Investments - ummary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	$ 96,207	$ 104,340
Unrealized Gains	1	39
Unrealized Losses	(16)	(25)
Fair Value	96,192	104,354
Investments \| U.S. treasuries
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	76,612	96,688
Unrealized Gains	1	39
Unrealized Losses	(10)	(22)
Fair Value	76,603	96,705
Investments \| U.S. government agency bonds
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost Basis	19,595	7,652
Unrealized Gains	0	0
Unrealized Losses	(6)	(3)
Fair Value	$ 19,589	$ 7,649

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Fair Value Measurements - Summary of Financial Assets Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	$ 96,192	$ 104,354
Fair Value, Measurements, Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	42,823	67,070
Short-term marketable securities	96,192	104,354
Total cash equivalents and short-term marketable securities	139,015	171,424
Fair Value, Measurements, Recurring Basis \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	42,823	67,070
Short-term marketable securities	96,192	104,354
Total cash equivalents and short-term marketable securities	139,015	171,424
Fair Value, Measurements, Recurring Basis \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term marketable securities	0	0
Total cash equivalents and short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis \| Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Short-term marketable securities	0	0
Total cash equivalents and short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis \| Money Market Funds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	42,823	67,070
Fair Value, Measurements, Recurring Basis \| Money Market Funds \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	42,823	67,070
Fair Value, Measurements, Recurring Basis \| Money Market Funds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring Basis \| Money Market Funds \| Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring Basis \| U.S. treasuries
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	76,603	96,705
Fair Value, Measurements, Recurring Basis \| U.S. treasuries \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	76,603	96,705
Fair Value, Measurements, Recurring Basis \| U.S. treasuries \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis \| U.S. treasuries \| Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis \| U.S. government agency bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	19,589	7,649
Fair Value, Measurements, Recurring Basis \| U.S. government agency bonds \| Level 1
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	19,589	7,649
Fair Value, Measurements, Recurring Basis \| U.S. government agency bonds \| Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	0	0
Fair Value, Measurements, Recurring Basis \| U.S. government agency bonds \| Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Short-term marketable securities	$ 0	$ 0

Leases - Additional Information (Details) $ in Millions	1 Months Ended	3 Months Ended
Leases - Additional Information (Details) $ in Millions	Dec. 31, 2019 USD ($)	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Mar. 27, 2023 USD ($) ft²
Lessee, Lease, Description [Line Items]
Cash paid for amounts included in measurement of operating lease liabilities		$ 1.8	$ 1.7
Operating lease, weighted-average remaining lease term		7 years 7 months 6 days
Operating lease, weighted-average discount rate		10.50%
2019 San Carlos Lease Agreement
Lessee, Lease, Description [Line Items]
Operating lease agreement initiation period	2019-12
Base term of lease	10 years 3 months
Lessee operating lease expected termination Period	2031-10
Lease term extension period	5 years
Area of lease \| ft²					95,692
Percentage of lease payments reduced					2.50%
Incremental borrowing rate					10.50%
Right of use asset and lease liability decreased					$ 5.6
Long-lived asset impairment charges		$ 12.4
Security deposit in the form of letter of credit secured by restricted cash		$ 1.5		$ 1.5
2019 San Carlos Lease Agreement \| Maximum
Lessee, Lease, Description [Line Items]
Tenant improvement allowance	$ 14.4

Stock-Based Compensation

3 Months Ended

Mar. 31, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

10. Stock-Based Compensation

Total stock-based compensation expense recognized is as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Research and development	$	1,273	$	4,675
General and administrative		4,937		5,990
Total	$	6,210	$	10,665

No income tax benefits for stock-based compensation expense have been recognized for the three months ended March 31, 2024 and 2023 as a result of the Company’s full valuation allowance applied to net deferred tax assets and net operating loss carryforwards.

Equity Incentive Plans

In July 2018, the Board of Directors adopted the 2018 Equity Incentive Plan (the “2018 Plan”). The 2018 Plan provides for the grant of incentive stock options, non-statutory stock options, restricted stock awards, restricted stock units (“RSUs”), stock appreciation rights, performance units and performance shares. The number of shares of common stock that may be issued under the 2018 Plan will automatically increase on each January 1, beginning with the fiscal year ending December 31, 2019, equal to the least of (i) 5,000,000 shares, (ii) 5% of the outstanding shares of common stock as of the last day of the preceding fiscal year or (iii) such other amount as the Board of Directors may determine. Stock options and RSUs granted under the 2018 Plan generally vest over four years and expire no more than 10 years from the date of grant.

Following the Company’s initial public offering and upon the effectiveness of the 2018 Plan, the Company’s 2012 Equity Incentive Plan, as amended, (the “2012 Plan”), terminated and no further awards will be granted thereunder. All outstanding awards under the 2012 Plan will continue to be governed by their existing terms. Any shares subject to awards granted under the 2012 Plan that, on or after the termination of the 2012 Plan, expire or terminate and shares previously issued pursuant to awards granted under the 2012 Plan that, on or after the termination of the 2012 Plan, are forfeited or repurchased by the Company will be transferred into the 2018 Plan. As of March 31, 2024, the maximum number of shares that may be added to the 2018 Plan pursuant to the preceding sentence is 2,520,969 shares.

Prior to its termination, the 2012 Plan provided for the grant of stock options, stock appreciation rights, restricted stock and RSUs to employees, directors and consultants. Stock options granted under the 2012 Plan generally vest over four years and expire no more than 10 years from the date of grant.

Stock Options

The following weighted-average assumptions were used to calculate the fair value of stock options granted during the periods indicated:


	Three Months Ended
	March 31,
	2024			2023
Risk-free interest rate		4.28	%		3.65	%
Expected volatility		101.27	%		95.86	%
Expected dividend yield		—			—
Expected term (in years)		5.41			6.08

The Company’s stock option activity during the three months ended March 31, 2024 is summarized as follows (number of shares in thousands):


				Weighted-
				Average
	Options			Exercise
	Outstanding			Price
Balance at December 31, 2023		7,968		$	10.85
Granted		5,674		$	1.25
Exercised		(26	)	$	0.97
Expired		(1	)	$	82.85
Forfeited		(322	)	$	14.87
Balance at March 31, 2024		13,293		$	6.67
Options exercisable		4,728		$	13.15
Options vested and expected to vest		12,752		$	6.86

As of March 31, 2024, total unrecognized stock-based compensation expense relating to unvested stock options was $17.0 million. This amount is expected to be recognized over a weighted-average period of 2.8 years.

Time-based RSUs

RSU activity under the 2018 Plan during the three months ended March 31, 2024 is summarized as follows (in thousands, except per share data):


				Weighted-
				Average
				Grant Date
	Shares			Fair Value
Balance at December 31, 2023		5,621		$	10.16
Granted		3,719		$	1.25
Vested		(670	)	$	11.47
Forfeited		(1,378	)	$	10.45
Balance at March 31, 2024		7,292		$	5.44

The weighted-average fair value of RSUs granted during the three months ended March 31, 2024 and 2023 was $1.25 and $7.20, respectively.

As of March 31, 2024, total unrecognized stock-based compensation expense relating to unvested RSUs was $35.4 million and the weighted-average remaining vesting period was 2.3 years.

Performance-based Restricted Stock Units (“PSUs”)

PSU activity under the 2018 Plan during the three months ended March 31, 2024 is summarized as follows (in thousands, except per share data):


				Weighted-
				Average
				Grant Date
	Shares			Fair Value
Balance at December 31, 2023		2,845		$	6.30
Forfeited/cancelled		(2,845	)	$	6.30
Balance at March 31, 2024		—		$	—

As of March 31, 2024, there were no outstanding PSUs.

Determining Fair Value

We estimate the fair value of share options granted using the Black-Scholes option pricing model. The Black-Scholes option pricing model requires the input of certain assumptions that involve judgment, for which changes can materially affect the resulting estimates of fair value. Starting January 1, 2024, we estimated the expected term based on historical exercise patterns and our expectation of the time that it will take for employees to exercise options still outstanding. Prior to 2024, due to limited trading history, we did not believe that our historical employee exercise data provided reasonable data for estimating our expected term for use in determining the

fair value of options. Therefore, for the period prior to 2024, the expected term of options was estimated based on the “simplified method” described by SEC Staff Accounting Bulletin No. 107, Share-Based Payment. There were no other changes to the assumptions and estimates related to determining the fair value of share options disclosed in our 2023 Annual Report on Form 10-K.

Employee Stock Purchase Plan

In July 2018, the Company’s Board of Directors and stockholders approved the 2018 Employee Stock Purchase Plan (the “2018 ESPP”). The number of shares of common stock that may be issued under the 2018 ESPP shall automatically increase on each January 1, beginning with the fiscal year ending December 31, 2019, equal to the least of (i) 1,000,000 shares, (ii) 1% of the outstanding shares of common stock as of the last day of the immediately preceding fiscal year and (iii) such other amount determined by the 2018 ESPP administrator. As of March 31, 2024, the number of shares available for issuance under the 2018 ESPP was 3,561,225.

Under the 2018 ESPP, employees may purchase shares of the Company’s common stock at a price per share equal to 85% of the lower of the fair market value of the common stock on the first trading day of the offering period or on the exercise date. The 2018 ESPP provides for consecutive, overlapping 24-month offering periods, each of which will include four 6-month purchase periods. The first offering period under the 2018 ESPP commenced on July 18, 2018.

During the three months ended March 31, 2024 and 2023, stock-based compensation expense related to the 2018 ESPP was $0.0 million and $0.3 million, respectively.

STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS (unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Operating expenses
Research and development	$ 34,824	$ 33,078
General and administrative	10,898	11,968
Impairment of long-lived assets	27,347	0
Total operating expenses	73,069	45,046
Loss from operations	(73,069)	(45,046)
Interest income	1,995	2,678
Other expense, net	(72)	(36)
Net loss	(71,146)	(42,404)
Unrealized gain (loss) on investments	(30)	296
Comprehensive loss	$ (71,176)	$ (42,108)
Net loss per common share:
Net loss per common share, basic	$ (0.81)	$ (0.49)
Net loss per common share, diluted	$ (0.81)	$ (0.49)
Weighted-average number of common shares outstanding:
Weighted-average shares of common stock outstanding, basic	88,042	85,845
Weighted-average shares of common stock outstanding, diluted	88,042	85,845

Leases - Summary of Classification of Company's Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Operating lease liabilities
Current portion included in accrued expenses and other current liabilities	$ 3,022	$ 3,250
Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration]	Accrued Liabilities, Current	Accrued Liabilities, Current
Operating lease liabilities, net of current portion	$ 37,408	$ 38,215
Total operating lease liabilities	$ 40,430	$ 41,465

Leases

3 Months Ended

Mar. 31, 2024

Leases [Abstract]

Leases

7. Leases

Operating Leases

The Company’s lease obligations primarily relate to leased office and laboratory space under a noncancelable operating lease. In accordance with ASC 842, the Company has performed an evaluation of its other contracts with vendors and has determined that, except for the leases described below, none of its other contracts contain a material lease.

2019 San Carlos Lease

In December 2019, the Company entered into an operating lease agreement for office and laboratory space in San Carlos, California (the “2019 San Carlos Lease”). The contractual term of the 2019 San Carlos Lease is 10.25 years from August 2021 until October 2031. The 2019 San Carlos Lease provides rent abatements and includes a one-time option to extend the lease term for five years. This option to extend the lease term was not determined to be reasonably certain and therefore has not been included in the Company’s calculation of the associated operating lease liability under ASC 842.

The 2019 San Carlos Lease includes monthly base rent amounts escalating over the term of the lease. In addition, the lessor provided for a tenant improvement allowance of up to $14.4 million, which was fully utilized and is recorded in lease obligations.

On March 27, 2023, the Company entered into an amendment for the 2019 San Carlos Lease, whereby rentable square feet was adjusted to 95,692 square feet and lease payments were reduced by approximately 2.5% per month, effective from January 1, 2022 through the end of the lease term. The Company accounted for these changes as a modification under ASC 842 and the operating right-of-use asset and lease liability were remeasured during the first quarter of 2023 utilizing an estimated incremental borrowing rate of 10.5%. Our estimated incremental borrowing rate was based on our estimated rate of interest for a fully collateralized borrowing over a similar term as the remaining lease payments while incorporating our credit risk. As a result of the modification, the right-of-use asset and lease liability decreased by approximately $5.6 million. No gain or loss was recognized upon the modification. As discussed in Note 5 – Impairment of Long-Lived Assets, the Company recognized long-lived asset impairment charges of $12.4 million on the right-of-use assets relating to the 2019 San Carlos Lease during the three months ended March 31, 2024.

Classification of Operating Leases

The 2019 San Carlos Lease required a security deposit of $1.5 million, which the Company satisfied by establishing a letter of credit secured by restricted cash. As of March 31, 2024 and December 31, 2023, a security deposit of $1.5 million for the 2019 San Carlos Lease was recorded as restricted cash in other long-term assets on the Company’s balance sheets.

Classification of the Company’s operating lease liabilities included on the Company’s balance sheets at March 31, 2024 and December 31, 2023 was as follows (in thousands):


	March 31,		December 31,
	2024		2023
Operating lease liabilities
Current portion included in accrued expenses and other current liabilities	$	3,022	$	3,250
Operating lease liabilities, net of current portion		37,408		38,215
Total operating lease liabilities	$	40,430	$	41,465

The components of lease costs included in operating expenses in the Company’s statements of operations and comprehensive loss were as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Operating lease costs	$	1,468	$	1,469
Variable costs		797		939
Total lease costs	$	2,265	$	2,408

Variable costs included in the table above represent amounts the Company pays related to property taxes, insurance, maintenance and repair costs.

Cash paid for amounts included in the measurement of the Company’s operating lease liabilities and presented within cash used in operating activities in the statements of cash flows was $1.8 million and $1.7 million for the three months ended March 31, 2024 and 2023, respectively.

Operating Lease Obligations

Future lease payments required under operating leases included on the Company’s balance sheet at March 31, 2024 are as follows (in thousands):


Fiscal Year Ending December 31,
2024 (remaining 9 months)	$	5,324
2025		7,287
2026		7,506
2027		7,731
2028		7,963
Thereafter		23,871
Total future lease payments		59,682
Less:
Present value adjustment		19,252
Operating lease liabilities	$	40,430

Operating lease liabilities are based on the net present value of the remaining lease payments over the remaining lease term. In determining the present value of lease payments, the Company used its incremental borrowing rate based on the information available at the lease commencement date. As of March 31, 2024, the weighted-average remaining lease term of the Company’s leases was 7.6 years and the weighted-average discount rate used to determine the operating lease liabilities included on the balance sheet was 10.5%.

As of March 31, 2024, the Company was not party to any lease agreements containing material residual value guarantees or material restrictive covenants.

Balance Sheet Components and Supplemental Disclosures - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 32,843	$ 47,777
Less accumulated depreciation	(15,479)	(14,408)
Property and equipment, net	17,364	33,369
Laboratory Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,993	6,993
Furniture And Office Equipment
Property Plant And Equipment [Line Items]
Property and equipment, gross	2,941	3,947
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment, gross	18,454	32,386
Capitalized Software
Property Plant And Equipment [Line Items]
Property and equipment, gross	4,382	4,382
Construction In Progress
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 73	$ 69

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2024	Mar. 31, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (71,146)	$ (42,404)

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
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+ Details

Stock-Based Compensation - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended
	Jul. 31, 2018	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Tax benefits for stock-based compensation expense recognized		$ 0	$ 0
Total unrecognized stock-based compensation expense relating to unvested stock options		$ 17,000,000
Weighted-average recognition period		2 years 9 months 18 days
Total stock-based compensation expense		$ 6,210,000	$ 10,665,000
Time-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average recognition period		2 years 3 months 18 days
Shares of performance-based restricted stock units		7,292,000		5,621,000
Weighted-average fair value of RSUs granted		$ 1.25	$ 7.2
Total unrecognized stock-based compensation expense		$ 35,400,000
2018 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares reserved for issuance per year	1,000,000
Percentage increase in shares reserved for issuance per year	1.00%
Price as a percentage of fair market value of common stock	85.00%
Consecutive overlapping offering period	24 months
Number of shares available for issuance		3,561,225
First offering period commence date	Jul. 18, 2018
Total stock-based compensation expense		$ 0	$ 300,000
Performance-based Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares of performance-based restricted stock units		0		2,845,000
2018 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Increase in number of common stock shares reserved for issuance per year	5,000,000
Percentage increase in shares reserved for issuance per year	5.00%
Award vesting period	4 years
Maximum number of additional shares authorized to be added to the Plan		2,520,969
2018 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years
2012 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period	4 years
2012 Equity Incentive Plan \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Option expiration period	10 years

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Summary of Financial Assets Measured at Fair Value on Recurring Basis

The Company measures and reports certain financial instruments as assets and liabilities at fair value on a recurring basis. The Company’s financial assets measured at fair value on a recurring basis were as follows (in thousands):


	March 31, 2024
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	42,823	$	—	$	—	$	42,823
Total cash equivalents		42,823		—		—		42,823
Short-term marketable securities
U.S. treasuries		76,603		—		—		76,603
U.S. government agency bonds		19,589		—		—		19,589
Total short-term marketable securities		96,192		—		—		96,192
Total cash equivalents and short-term marketable securities	$	139,015	$	—	$	—	$	139,015


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	67,070	$	—	$	—	$	67,070
Total cash equivalents		67,070		—		—		67,070
Short-term marketable securities:
U.S. treasuries		96,705		—		—		96,705
U.S. government agency bonds		7,649		—		—		7,649
Total short-term marketable securities		104,354		—		—		104,354
Total cash equivalents and short-term marketable securities	$	171,424	$	—	$	—	$	171,424

Summary of Significant Accounting Policies - Calculation of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Numerator:
Net Income (Loss)	$ (71,146)	$ (42,404)
Denominator:
Weighted-average shares of common stock outstanding, basic	88,042	85,845
Weighted-average shares of common stock outstanding, diluted	88,042	85,845
Net loss per share, basic	$ (0.81)	$ (0.49)
Net loss per share, diluted	$ (0.81)	$ (0.49)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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- Definition

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-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(25))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(27))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(23))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 15: http://www.xbrl.org/2003/role/exampleRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 52
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482635/260-10-55-52

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482689/260-10-45-7

+ Details

- Definition

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

+ References

+ Details

Summary of Significant Accounting Policies (Policies)

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Basis of Presentation

The unaudited interim financial statements have been prepared in accordance with United States generally accepted accounting principles (“U.S. GAAP”). The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts and disclosures reported in the financial statements and accompanying notes.

The interim balance sheet as of March 31, 2024, the statements of operations and comprehensive loss, statements of stockholders’ equity for the three months ended March 31, 2024 and 2023 and statements of cash flows for the three months ended March 31, 2024 and 2023 are unaudited. The unaudited interim financial statements have been prepared on the same basis as the audited annual financial statements and reflect, in the opinion of management, all adjustments of a normal and recurring nature that are necessary for the fair presentation of the Company’s financial position as of March 31, 2024 and its results of operations and comprehensive loss for the three months ended March 31, 2024 and 2023 and its cash flows for the three months ended March 31, 2024 and 2023. Certain information and note disclosures normally included in annual audited financial statements prepared in accordance with U.S. GAAP have been omitted. The financial data and the other financial information disclosed in these notes to the interim financial statements are also unaudited. The results of operations for any interim period are not necessarily indicative of the results to be expected for the entire year or for any other future annual or interim period. These interim financial statements should be read in conjunction with the Company’s audited financial statements included in the Company’s Annual Report on Form 10-K, which was filed with the U.S. Securities and Exchange Commission (“SEC”) on March 14, 2024.

Use of Estimates

Management uses significant judgment when making estimates related to common stock valuation and related stock-based compensation expense, accrued research and development expense, valuation of long-lived assets and lease-related assets and liabilities. Management bases its estimates on historical experience and on various other assumptions that are believed to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates under different assumptions or conditions, and those differences could be material to the financial position and results of operations.

Concentration of Credit Risk and Other Risks and Uncertainties

Financial instruments that potentially subject the Company to credit risk principally consist of cash, cash equivalents and investments. These financial instruments are currently held in accounts in varying amounts at four separate financial institutions that management believes possess high credit quality. Amounts on deposit with these financial institutions have and will continue to exceed federally-insured limits. The Company has not experienced any losses on its cash deposits. Additionally, the Company’s investment policy limits its investments to certain types of securities issued by or backed by the U.S. government and its agencies.

The Company is subject to a number of risks similar to that of other early stage biopharmaceutical companies, including, but not limited to, the need to obtain adequate additional funding, possible failure of current or future clinical trials, its reliance on third-parties to conduct its clinical trials, the need to obtain regulatory and marketing approvals for its product candidates, competitive developments, the need to successfully commercialize and gain market acceptance of the Company’s product candidates, protection of proprietary technology, and the need to secure and maintain adequate manufacturing arrangements with third-parties. If the Company does not successfully commercialize or partner its product candidates, it will be unable to generate product revenue or achieve profitability.

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.

The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the Company’s balance sheets and which, in aggregate, represent the amounts reported in the accompanying statements of cash flows (in thousands):


	March 31,		December 31,
	2024		2023
Cash and cash equivalents	$	43,060	$	66,440
Restricted cash in other long-term assets		1,472		1,472
Total	$	44,532	$	67,912


	March 31,		December 31,
	2023		2022
Cash and cash equivalents	$	93,854	$	87,217
Restricted cash in other long-term assets		1,472		1,472
Total	$	95,326	$	88,689

Restricted cash at March 31, 2024 represents $1.5 million in security deposits for the lease of the Company’s facility in San Carlos, California. The security deposit is in the form of a letter of credit secured by restricted cash and is recorded in other long-term assets on the Company’s balance sheets

Investments

The Company invests in marketable securities, primarily securities issued by the U.S. government and its agencies. The Company’s investments are considered available-for-sale and are classified as current assets even when the stated maturities of the underlying securities exceed one year from the date of the current balance sheet being reported. This classification reflects management’s ability and intent to utilize proceeds from the sale of such investments to fund ongoing operations. Unrealized gains and losses are excluded from earnings and are reported as a component of accumulated other comprehensive gain (loss) unless the decline in fair value of the investments is attributable to expected credit losses and if it is more likely than not that the Company will be required or will intend to sell the investment before recovery of its amortized cost basis. The cost of securities sold is determined using the specific-identification method. Interest earned and adjustments for the amortization of premiums and discounts on investments are included in interest income on the statements of operations and comprehensive loss. Realized gains and losses on the sale of investments are included in other expense, net, on the statements of operations and comprehensive loss.

Valuation of Long-lived Assets

Long-lived assets, including property and equipment and finite-lived intangible assets, are reviewed for possible impairment whenever events or circumstances indicate that the carrying amount of such assets may not be recoverable. The evaluation is performed at the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of these assets is measured by a comparison of the carrying amounts to the future undiscounted cash flows the assets are expected to generate from the use and eventual disposition. If such review indicates that the carrying amount of the long-lived assets is not recoverable, the carrying amount of such assets is reduced to fair value. We have recorded impairment charges during the quarter

ended March 31, 2024. For a further description of the impairment, see Note 5 – Impairment of Long-Lived Assets in the accompanying notes.

Operating Leases

The Company accounts for its leases in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 842, “Leases” (“ASC 842”). Right-of-use assets represent the Company’s right to use an underlying asset over the lease term and include any lease payments made prior to the lease commencement date and are reduced by lease incentives. Lease liabilities represent the present value of the total lease payments over the lease term, calculated using the Company’s incremental borrowing rate. In determining the Company’s incremental borrowing rate, consideration is given to the term of the lease and the Company’s credit risk. The Company recognizes options to extend a lease when it is reasonably certain that it will exercise such extension. The Company does not recognize options to terminate a lease when it is reasonably certain that it will not exercise such early termination options. Lease expense is recognized on a straight-line basis over the expected lease term.

Accrued Research and Development Expense

Service agreements with contract development and manufacturing organizations (“CDMOs”), clinical contract research organizations (“CROs”) and clinical investigative sites comprise a significant component of the Company’s research and development activities. External costs for these vendors are recognized as the services are incurred. The Company accrues for expenses resulting from obligations under agreements with its third-parties for which the timing of payments does not match the periods over which the materials or services are provided to the Company. Accruals are recorded based on estimates of services received and efforts expended pursuant to agreements established with CDMOs, clinical CROs, clinical investigative sites and other outside service providers. These estimates are typically based on contracted amounts applied to the proportion of work performed and determined through analysis with internal personnel and external service providers as to the progress or stage of completion of the services.

The Company makes judgements and estimates in determining the accrual balance in each reporting period. In the event advance payments are made to a CDMO, clinical CRO, clinical investigative site or other outside service provider, the payments are recorded within prepaid expenses and other current assets or other long-term assets, as appropriate, and subsequently recognized as research and development expense when the associated services have been performed. As actual costs become known, the Company adjusts its liabilities and assets. Inputs, such as the extent of services received and the duration of services to be performed, may vary from the Company’s estimates, which will result in adjustments to research and development expense in future periods. Changes in these estimates that result in material changes to the Company’s accruals could materially affect the Company’s results of operations. The Company’s historical estimates have not been materially different from actual amounts recorded.

Research and Development Expense

Research and development costs are expensed as incurred. Research and development costs include, among others, consulting costs, salaries, benefits, travel, stock-based compensation, laboratory supplies and other non-capital equipment utilized for in-house research, allocation of facilities and overhead costs and external costs paid to third-parties that conduct research and development activities on the Company’s behalf. Costs to terminate commitments with third-party suppliers performing research and development activities and amounts incurred in connection with license agreements, including milestone payments, are also included in research and development expense.

Advance payments for goods or services to be rendered in the future for use in research and development activities are deferred and included in prepaid expenses and other current assets or other long-term assets, as appropriate. The deferred amounts are expensed as the related goods are delivered or the services are performed.

Comprehensive Loss

Comprehensive loss is defined as the change in stockholders’ equity during a period from transactions and other events and circumstances from non-owner sources. The differences between net loss and comprehensive loss for the three months ended March 31, 2024 and 2023 are a result of unrealized gains and losses on the Company’s investments in marketable securities included in current assets on the Company’s balance sheets.

Net Loss per Share

The Company calculates basic net loss per share by dividing the net loss attributable to common stockholders by the weighted-average shares of common stock outstanding during the period. The Company calculates diluted net loss per share after giving

consideration to all potentially dilutive securities outstanding during the period using the treasury-stock and if-converted methods, except where the effect of including such securities would be anti-dilutive. Because the Company has reported net losses since inception, the effect from potentially dilutive securities would have been anti-dilutive and therefore has been excluded from the calculation of diluted net loss per share.

Basic and diluted net loss per share was calculated as follows (in thousands, except per share data):


	Three Months Ended
	March 31,
	2024			2023
Numerator:
Net loss	$	(71,146	)	$	(42,404	)
Denominator:
Weighted-average shares of common stock outstanding, basic and diluted		88,042			85,845
Net loss per share, basic and diluted	$	(0.81	)	$	(0.49	)

The following table sets forth the potentially dilutive securities that have been excluded from the calculation of diluted net loss per share due to their anti-dilutive effect for the periods indicated (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Options to purchase common stock		13,293		6,830
Unvested restricted stock units		7,292		6,142
Unvested performance stock units		—		3,062
Shares issuable under employee stock purchase plans		71		59
Total		20,656		16,093

Recently Issued and Adopted Accounting Pronouncements

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This ASU requires entities to expand their existing income tax disclosures, specifically related to the rate reconciliation and income taxes paid. This authoritative guidance will be effective for us in fiscal year 2025, with early adoption permitted. The Company is currently evaluating the impact of the ASU, but does not expect any material impacts upon adoption.

Organization and Business

3 Months Ended

Mar. 31, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Business

1. Organization and Business

Allakos Inc. (“Allakos” or the “Company”) was incorporated in the State of Delaware in March 2012. Allakos is a clinical stage biopharmaceutical company focused on developing therapeutics which target immunomodulatory receptors present on immune effector cells involved in allergic, inflammatory and proliferative diseases. Our most advanced product candidate is AK006 which targets mast cells. Inappropriately activated mast cells have been identified as key drivers in a number of severe diseases affecting the gastrointestinal tract, eyes, skin, lungs and other organs. The Company’s primary activities to date have included establishing its facilities, recruiting personnel, conducting research and development of its product candidates and raising capital. The Company’s operations are located in San Carlos, California. The Company operates in one reportable segment.

Liquidity Matters

Since inception, the Company has incurred net losses and negative cash flows from operations. During the three months ended March 31, 2024, the Company incurred a net loss of $71.1 million. At March 31, 2024, the Company had an accumulated deficit of $1,189.6 million and does not expect to experience positive cash flows from operating activities in the foreseeable future. The Company has financed its operations to date primarily through the sale of common stock. Management expects to incur additional operating losses in the future as the Company continues to further develop, seek regulatory approval for and, if approved, commence commercialization of its product candidates.

On January 16, 2024, the Company announced that due to unfavorable clinical trial results associated with the use of lirentelimab in its Phase 2 atopic dermatitis and Phase 2b chronic spontaneous urticaria trials, that the Company would halt lirentelimab-related activities across clinical, manufacturing, research and administrative functions. Accordingly, the Company’s Board of Directors approved a reorganization plan to reduce operating costs and better align our workforce with our current clinical development plans of our business (the “2024 Reorganization Plan”). Under the 2024 Reorganization Plan, the Company’s workforce was reduced by approximately 50% primarily during the first quarter of 2024.

The Company had $139.3 million of cash, cash equivalents and marketable securities at March 31, 2024. Management believes that this amount is sufficient to fund the Company’s operations for at least the next 12 months from the issuance date of these financial statements.

Contingencies

3 Months Ended

Mar. 31, 2024

Commitments and Contingencies Disclosure [Abstract]

Contingencies

8. Contingencies

Indemnification Agreements

The Company has entered into indemnification agreements with certain directors and officers that require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or service as directors or officers. To date, no such matters have arisen and the Company does not believe that the outcome of any claims under indemnification arrangements will have a material adverse effect on its financial positions, results of operations or cash flows. Accordingly, the Company has not recorded a liability related to such indemnifications at March 31, 2024.

Investments (Tables)

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost, Gross Unrealized Holding Gains or Losses, and Fair Value of Investments

All investments were considered available-for-sale at March 31, 2024. The amortized cost, gross unrealized holding gains or losses, and fair value of the Company’s investments by major security type at March 31, 2024 and December 31, 2023 are summarized in the table below (in thousands):


	March 31, 2024
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Available-for-sale securities:
U.S. treasuries classified as investments	$	76,612	$	1	$	(10	)	$	76,603
U.S. government agency bonds		19,595		—		(6	)		19,589
Total available-for-sale securities	$	96,207	$	1	$	(16	)	$	96,192


	December 31, 2023
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Available-for-sale securities:
U.S. treasuries classified as investments	$	96,688	$	39	$	(22	)	$	96,705
U.S. government agency bonds		7,652		—		(3	)		7,649
Total available-for-sale securities	$	104,340	$	39	$	(25	)	$	104,354

- Definition

Tabular disclosure of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-9

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 11: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-3

+ Details

Investments

3 Months Ended

Mar. 31, 2024

Investments, Debt and Equity Securities [Abstract]

Investments

4. Investments


	March 31, 2024
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Available-for-sale securities:
U.S. treasuries classified as investments	$	76,612	$	1	$	(10	)	$	76,603
U.S. government agency bonds		19,595		—		(6	)		19,589
Total available-for-sale securities	$	96,207	$	1	$	(16	)	$	96,192


	December 31, 2023
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses			Fair Value
Available-for-sale securities:
U.S. treasuries classified as investments	$	96,688	$	39	$	(22	)	$	96,705
U.S. government agency bonds		7,652		—		(3	)		7,649
Total available-for-sale securities	$	104,340	$	39	$	(25	)	$	104,354

The amortized cost of available-for-sale securities is adjusted for amortization of premiums and accretion of discounts to maturity. As of March 31, 2024 and December 31, 2023, the aggregate fair value of securities held by the Company in an unrealized loss position for less than twelve months was $81.0 million and $53.7 million, respectively. These securities had remaining maturities of less than one year. The Company has the intent and ability to hold such securities until recovery and has determined that there has been no material change to their credit risk. As a result, the Company determined it did not hold any investments with a credit loss at March 31, 2024 and December 31, 2023.

There were no material realized gains or losses recognized on the sale or maturity of available-for-sale securities during the three months ended March 31, 2024 and 2023, and as a result, there were no material reclassifications out of accumulated other comprehensive gain (loss) for the same periods.

Contingencies - Additional Information (Details) - USD ($) shares in Thousands	Mar. 31, 2024	Dec. 31, 2023
Loss Contingencies [Line Items]
Common stock, shares issued	88,544	87,750
Indemnification Agreements [Member]
Loss Contingencies [Line Items]
Liability related to indemnifications	$ 0

Balance Sheet Components and Supplemental Disclosures - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Balance Sheet Related Disclosures [Line Items]
Depreciation and amortization	$ 1,072	$ 1,524
Long-lived asset impairment charges	27,347	$ 0
Leasehold Improvements
Balance Sheet Related Disclosures [Line Items]
Long-lived asset impairment charges	13,900
Furniture And Office Equipment
Balance Sheet Related Disclosures [Line Items]
Long-lived asset impairment charges	$ 1,000

Stock-Based Compensation - Summary of Total Stock-Based Compensation Expense Recognized (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 6,210	$ 10,665
Research and Development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	1,273	4,675
General and Administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 4,937	$ 5,990

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Restricted cash in other long term assets, deposit for lease facility	$ 1,472	$ 1,472	$ 1,472	$ 1,472

Balance Sheet Components and Supplemental Disclosures (Tables)

3 Months Ended

Mar. 31, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Property and Equipment, Net

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


	March 31,			December 31,
	2024			2023
Laboratory equipment	$	6,993		$	6,993
Furniture and office equipment		2,941			3,947
Leasehold improvements		18,454			32,386
Capitalized software		4,382			4,382
Construction-in-progress		73			69
		32,843			47,777
Less accumulated depreciation		(15,479	)		(14,408	)
Property and equipment, net	$	17,364		$	33,369

Schedule of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following (in thousands):


	March 31,		December 31,
	2024		2023
Accrued contract research and development expense	$	13,213	$	22,262
Accrued compensation and benefits expense		2,894		8,674
Current portion of operating lease liabilities		3,022		3,250
Other current liabilities		1,044		628
Total	$	20,173	$	34,814

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Reconciliation of Cash, Cash Equivalents and Restricted Cash


	March 31,		December 31,
	2024		2023
Cash and cash equivalents	$	43,060	$	66,440
Restricted cash in other long-term assets		1,472		1,472
Total	$	44,532	$	67,912


	March 31,		December 31,
	2023		2022
Cash and cash equivalents	$	93,854	$	87,217
Restricted cash in other long-term assets		1,472		1,472
Total	$	95,326	$	88,689

Calculation of Basic and Diluted Net Loss Per Share

Basic and diluted net loss per share was calculated as follows (in thousands, except per share data):


	Three Months Ended
	March 31,
	2024			2023
Numerator:
Net loss	$	(71,146	)	$	(42,404	)
Denominator:
Weighted-average shares of common stock outstanding, basic and diluted		88,042			85,845
Net loss per share, basic and diluted	$	(0.81	)	$	(0.49	)

Summary of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss Per Share


	Three Months Ended
	March 31,
	2024		2023
Options to purchase common stock		13,293		6,830
Unvested restricted stock units		7,292		6,142
Unvested performance stock units		—		3,062
Shares issuable under employee stock purchase plans		71		59
Total		20,656		16,093

Impairment of Long-Lived Assets

3 Months Ended

Mar. 31, 2024

Asset Impairment Charges [Abstract]

Impairment of Long-Lived Assets

5. Impairment of Long-Lived Assets

During the three months ended March 31, 2024, as a result of the significant sustained decline observed in the Company’s stock price and related market capitalization following our decision to halt the development of lirentelimab, the Company performed an impairment assessment of long-lived assets. The Company determined that the long-lived assets held and used did not have identifiable cash flows that are largely independent of the cash flows of other assets and liabilities. Therefore, the Company evaluated its long-lived assets for impairment on an entity-wide level. The Company concluded that the carrying value of the entity-wide asset group was not recoverable as it exceeded the future net undiscounted cash flows. To measure, allocate and recognize the impairment loss, the Company determined individual fair values of its long-lived assets. The Company utilized the income approach for estimating the fair value of

right of use assets and related leasehold improvements by estimating the potential cash flows from a hypothetical fully-furnished sublease and applying a discount rate. The cost replacement method was used to estimate the fair value of laboratory and office equipment, capitalized software, and assets to be placed into service or in the process of construction. These represented level 3 nonrecurring fair value measurements. Based on this analysis, the Company recorded a $27.3 million charge to Impairment of long-lived assets in the Statement of Operations and Comprehensive Loss for the quarter ended March 31, 2024, of which $12.4 million was attributed to right-of-use assets, $13.9 million to leasehold improvements, and $1.0 million to furniture. No impairment was recognized on the remaining long-lived assets as their carrying values were not in excess of their fair values.

Leases - Summary of Components of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Leases [Abstract]
Operating lease costs	$ 1,468	$ 1,469
Variable costs	797	939
Total lease costs	$ 2,265	$ 2,408

Fair Value Measurements - Additional Information (Details) - USD ($)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Transfers of assets between level 1 to level 2	$ 0	$ 0
Transfers of assets between level 2 to level 1	0	0
Transfers of liabilities between level 1 to level 2	0	0
Transfers of liabilities between level 2 to level 1	0	0
Transfers of assets into level 3	0	0
Transfers of assets out of level 3	0	0
Transfers of liabilities into level 3	0	0
Transfers of liabilities out of level 3	$ 0	$ 0

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Fair Value Measurements

3 Months Ended

Mar. 31, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

3. Fair Value Measurements


	March 31, 2024
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	42,823	$	—	$	—	$	42,823
Total cash equivalents		42,823		—		—		42,823
Short-term marketable securities
U.S. treasuries		76,603		—		—		76,603
U.S. government agency bonds		19,589		—		—		19,589
Total short-term marketable securities		96,192		—		—		96,192
Total cash equivalents and short-term marketable securities	$	139,015	$	—	$	—	$	139,015


	December 31, 2023
	Level 1		Level 2		Level 3		Total
Cash equivalents:
Money market funds	$	67,070	$	—	$	—	$	67,070
Total cash equivalents		67,070		—		—		67,070
Short-term marketable securities:
U.S. treasuries		96,705		—		—		96,705
U.S. government agency bonds		7,649		—		—		7,649
Total short-term marketable securities		104,354		—		—		104,354
Total cash equivalents and short-term marketable securities	$	171,424	$	—	$	—	$	171,424

The Company evaluates transfers between levels at the end of each reporting period. There were no transfers of assets or liabilities between levels during the three months ended March 31, 2024 and 2023.

- Definition

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

+ References + Details

STATEMENTS OF CASH FLOWS (unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash flows from operating activities
Net Income (Loss)	$ (71,146)	$ (42,404)
Adjustments to reconcile net loss to net cash used in operating activities:
Impairment of long-lived assets	27,347	0
Depreciation and amortization	1,072	1,524
Stock-based compensation	6,210	10,665
Net accretion of premiums and discounts on investments	(962)	(1,474)
Noncash lease expense	1,149	474
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	774	(1,195)
Other long-term assets	4,479	3,227
Accounts payable	13,984	4,385
Accrued expenses and other current liabilities	(14,641)	(4,475)
Operating lease liabilities, net of current portion	(807)	(866)
Net cash used in operating activities	(32,541)	(30,139)
Cash flows from investing activities
Purchases of investments	(34,367)	(49,415)
Proceeds from maturities of investments	43,400	85,000
Purchases of property and equipment	(4)	(267)
Net cash provided by investing activities	9,029	35,318
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs	0	990
Proceeds from exercise of stock options	26	26
Proceeds from issuance of common stock under the 2018 ESPP	106	442
Net cash provided by financing activities	132	1,458
Net increase (decrease) in cash, cash equivalents and restricted cash	(23,380)	6,637
Cash, cash equivalents and restricted cash, beginning of period	67,912	88,689
Cash, cash equivalents and restricted cash, end of period	44,532	95,326
Noncash investing and financing items:
Noncash adjustments to right-of-use assets upon lease amendment	$ 0	$ (5,617)

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2024

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Total Stock-Based Compensation Expense Recognized

Total stock-based compensation expense recognized is as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Research and development	$	1,273	$	4,675
General and administrative		4,937		5,990
Total	$	6,210	$	10,665

Summary of Weighted-Average Assumptions Used to Calculate Fair Value of Stock Options Granted

The following weighted-average assumptions were used to calculate the fair value of stock options granted during the periods indicated:


	Three Months Ended
	March 31,
	2024			2023
Risk-free interest rate		4.28	%		3.65	%
Expected volatility		101.27	%		95.86	%
Expected dividend yield		—			—
Expected term (in years)		5.41			6.08

Summary of Stock Option Activity

The Company’s stock option activity during the three months ended March 31, 2024 is summarized as follows (number of shares in thousands):


				Weighted-
				Average
	Options			Exercise
	Outstanding			Price
Balance at December 31, 2023		7,968		$	10.85
Granted		5,674		$	1.25
Exercised		(26	)	$	0.97
Expired		(1	)	$	82.85
Forfeited		(322	)	$	14.87
Balance at March 31, 2024		13,293		$	6.67
Options exercisable		4,728		$	13.15
Options vested and expected to vest		12,752		$	6.86

Time-based Restricted Stock Units

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Restricted Stock Units

RSU activity under the 2018 Plan during the three months ended March 31, 2024 is summarized as follows (in thousands, except per share data):


				Weighted-
				Average
				Grant Date
	Shares			Fair Value
Balance at December 31, 2023		5,621		$	10.16
Granted		3,719		$	1.25
Vested		(670	)	$	11.47
Forfeited		(1,378	)	$	10.45
Balance at March 31, 2024		7,292		$	5.44

Performance-based Restricted Stock Units

Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]

Summary of Restricted Stock Units

PSU activity under the 2018 Plan during the three months ended March 31, 2024 is summarized as follows (in thousands, except per share data):


				Weighted-
				Average
				Grant Date
	Shares			Fair Value
Balance at December 31, 2023		2,845		$	6.30
Forfeited/cancelled		(2,845	)	$	6.30
Balance at March 31, 2024		—		$	—

- Definition

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

+ References

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

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org//1943274/2147480483/718-10-35-3

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480429/718-10-50-2

+ Details

Organization and Business - Additional Information (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2024 USD ($) Segment	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of reportable segments \| Segment	1
Net loss	$ 71,146	$ 42,404
Reduction in company's workforce	50.00%
Accumulated deficit	$ 1,189,623		$ 1,118,477
Cash, cash equivalents and marketable securities	$ 139,300

- Definition

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

+ References

+ Details

- Definition

Amount of accumulated undistributed earnings (deficit).

+ References + Details

Impairment of Long-Lived Assets - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges	$ 27,347	$ 0
Leasehold Improvements
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges	13,900
Right Of Use Asset
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges	12,400
Furniture And Office Equipment
Property, Plant and Equipment [Line Items]
Long-lived asset impairment charges	$ 1,000

Balance Sheet Components and Supplemental Disclosures - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Payables and Accruals [Abstract]
Accrued contract research and development expense	$ 13,213	$ 22,262
Accrued compensation and benefits expense	2,894	8,674
Current portion of operating lease liabilities	3,022	3,250
Other current liabilities	1,044	628
Total	$ 20,173	$ 34,814

STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	ATM Offering [Member]	Common Stock	Common Stock ATM Offering [Member]	Additional Paid-In Capital	Additional Paid-In Capital ATM Offering [Member]	Accumulated Other Comprehensive Gain (Loss)	Accumulated Other Comprehensive Gain (Loss) ATM Offering [Member]	Accumulated Deficit	Accumulated Deficit ATM Offering [Member]
Balance at Dec. 31, 2022	$ 310,433		$ 85		$ 1,243,408		$ (284)		$ (932,776)
Balance, Shares at Dec. 31, 2022			85,387
Stock-based compensation expense	10,665		$ 0		10,665		0		0
Issuance of common stock upon exercise of stock options	26		$ 0		26		0		0
Issuance of common stock upon exercise of stock options, Shares			6
Issuance of common stock upon 2018 ESPP purchase	442		$ 0		442		0		0
Issuance of common stock upon 2018 ESPP purchase, Shares			144
Issuance of common stock upon vesting of restricted stock units	0		$ 1		(1)		0		0
Issuance of common stock upon vesting of restricted stock units, Shares			881
Issuance of common stock under the ATM / registered direct Offering net of issuance costs		$ 990		$ 0		$ 990		$ 0		$ 0
Issuance of common stock under the ATM /registered direct Offering net of issuance costs, Shares				142
Unrealized gain (loss) on investments	296		$ 0		0		296		0
Net Income (Loss)	(42,404)		0		0		0		(42,404)
Balance at Mar. 31, 2023	280,448		$ 86		1,255,530		12		(975,180)
Balance, Shares at Mar. 31, 2023			86,560
Balance at Dec. 31, 2023	168,817		$ 88		1,287,156		50		(1,118,477)
Balance, Shares at Dec. 31, 2023			87,750
Stock-based compensation expense	6,210		$ 0		6,210		0		0
Issuance of common stock upon exercise of stock options	$ 26		$ 0		26		0		0
Issuance of common stock upon exercise of stock options, Shares	26		26
Issuance of common stock upon 2018 ESPP purchase	$ 106		$ 0		106		0		0
Issuance of common stock upon 2018 ESPP purchase, Shares			98
Issuance of common stock upon vesting of restricted stock units	0		$ 1		(1)		0		0
Issuance of common stock upon vesting of restricted stock units, Shares			670
Unrealized gain (loss) on investments	(30)		$ 0		0		(30)		0
Net Income (Loss)	(71,146)		0		0		0		(71,146)
Balance at Mar. 31, 2024	$ 103,983		$ 89		$ 1,293,497		$ 20		$ (1,189,623)
Balance, Shares at Mar. 31, 2024			88,544

Summary of Significant Accounting Policies - Summary of Potentially Dilutive Securities Excluded from Calculation of Diluted Net Loss per Share (Details) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	20,656	16,093
Employee Stock Option
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	13,293	6,830
Unvested Restricted Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	7,292	6,142
Unvested Performance Stock Units
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	0	3,062
Shares Issuable under Employee Stock Purchase Plans
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Potentially dilutive securities excluded from calculation of diluted net loss per share due to anti-dilutive effect	71	59

Stockholders' Equity

3 Months Ended

Mar. 31, 2024

Stockholders' Equity Note [Abstract]

Stockholders' Equity

9. Stockholders’ Equity

“At-the-Market” Equity Offering

On August 4, 2022, the Company entered into a sales agreement (the “2022 Sales Agreement”) with Cowen and Company, LLC (“Cowen”). Pursuant to the 2022 Sales Agreement, the Company may sell, from time to time, up to an aggregate of $75.0 million in gross sales proceeds of its common stock through an “at-the-market” offering (“ATM Offering”) as defined under the Securities Act. The Company will pay a commission equal to 3% of the gross proceeds from the sale of shares of its common stock under the 2022 Sales Agreement. The $75.0 million of common stock that may be offered, issued and sold in the ATM Offering is included in the $250.0 million of securities that may be offered, issued and sold by the Company under its registration statement on Form S-3 (File No. 333-265085). The Company expects to use the net proceeds from sales under the 2022 Sales Agreement for general corporate purposes.

No shares were sold during the three months ended March 31, 2024 through the Company's ATM Offering. During the three months ended March 31, 2023, the Company sold 0.1 million shares of its common stock at an average price of $7.20 per share through its ATM Offering, resulting in proceeds of $1.0 million net of commissions. Under the ATM Offering, $74.0 million of common stock remain available for future sales as of March 31, 2024; however, the Company is not obligated to make any sales under this program.

- Definition

The entire disclosure for equity.

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 14
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 6
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-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-Publisher FASB
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Topic 505
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Leases - Summary of Future Lease Payments Required Under Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024 (remaining 9 months)	$ 5,324
2025	7,287
2026	7,506
2027	7,731
2028	7,963
Thereafter	23,871
Total future lease payments	59,682
Present value adjustment	19,252
Operating lease liabilities	$ 40,430	$ 41,465

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Basis of Presentation

Use of Estimates

Concentration of Credit Risk and Other Risks and Uncertainties

Cash, Cash Equivalents and Restricted Cash

The Company considers all highly liquid investments with original maturities of three months or less from the date of purchase to be cash equivalents.


	March 31,		December 31,
	2024		2023
Cash and cash equivalents	$	43,060	$	66,440
Restricted cash in other long-term assets		1,472		1,472
Total	$	44,532	$	67,912


	March 31,		December 31,
	2023		2022
Cash and cash equivalents	$	93,854	$	87,217
Restricted cash in other long-term assets		1,472		1,472
Total	$	95,326	$	88,689

Investments

Valuation of Long-lived Assets

ended March 31, 2024. For a further description of the impairment, see Note 5 – Impairment of Long-Lived Assets in the accompanying notes.

Operating Leases

Accrued Research and Development Expense

Research and Development Expense

Comprehensive Loss

Net Loss per Share

Basic and diluted net loss per share was calculated as follows (in thousands, except per share data):


	Three Months Ended
	March 31,
	2024			2023
Numerator:
Net loss	$	(71,146	)	$	(42,404	)
Denominator:
Weighted-average shares of common stock outstanding, basic and diluted		88,042			85,845
Net loss per share, basic and diluted	$	(0.81	)	$	(0.49	)


	Three Months Ended
	March 31,
	2024		2023
Options to purchase common stock		13,293		6,830
Unvested restricted stock units		7,292		6,142
Unvested performance stock units		—		3,062
Shares issuable under employee stock purchase plans		71		59
Total		20,656		16,093

Recently Issued and Adopted Accounting Pronouncements

Leases (Tables)

3 Months Ended

Mar. 31, 2024

Leases [Abstract]

Summary of Classification of Company's Operating Lease Liabilities

Classification of the Company’s operating lease liabilities included on the Company’s balance sheets at March 31, 2024 and December 31, 2023 was as follows (in thousands):


	March 31,		December 31,
	2024		2023
Operating lease liabilities
Current portion included in accrued expenses and other current liabilities	$	3,022	$	3,250
Operating lease liabilities, net of current portion		37,408		38,215
Total operating lease liabilities	$	40,430	$	41,465

Summary of Components of Lease Costs

The components of lease costs included in operating expenses in the Company’s statements of operations and comprehensive loss were as follows (in thousands):


	Three Months Ended
	March 31,
	2024		2023
Operating lease costs	$	1,468	$	1,469
Variable costs		797		939
Total lease costs	$	2,265	$	2,408

Summary of Future Lease Payments Required Under Operating Leases

Future lease payments required under operating leases included on the Company’s balance sheet at March 31, 2024 are as follows (in thousands):


Fiscal Year Ending December 31,
2024 (remaining 9 months)	$	5,324
2025		7,287
2026		7,506
2027		7,731
2028		7,963
Thereafter		23,871
Total future lease payments		59,682
Less:
Present value adjustment		19,252
Operating lease liabilities	$	40,430

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2024	May 03, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q1
Trading Symbol	ALLK
Entity Registrant Name	Allakos Inc.
Entity Central Index Key	0001564824
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Common Stock, Shares Outstanding		88,544,474
Entity Current Reporting Status	Yes
Entity Shell Company	false
Entity File Number	001-38582
Entity Tax Identification Number	45-4798831
Entity Address, Address Line One	825 Industrial Road
Entity Address, Address Line Two	Suite 500
Entity Address, City or Town	San Carlos
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94070
City Area Code	650
Local Phone Number	597-5002
Entity Interactive Data Current	Yes
Title of 12(b) Security	Common Stock, par value $0.001
Security Exchange Name	NASDAQ
Document Quarterly Report	true
Document Transition Report	false
Entity Incorporation, State or Country Code	DE

Stock-Based Compensation - Summary of Stock Option Activity (Details) shares in Thousands	3 Months Ended
	Mar. 31, 2024 $ / shares shares
Share-Based Payment Arrangement [Abstract]
Options Outstanding, Beginning balance \| shares	7,968
Options Outstanding, Granted \| shares	5,674
Options Outstanding, Exercised \| shares	(26)
Options outstanding, Expired \| shares	(1)
Options Outstanding, forfeited \| shares	(322)
Options Outstanding, Ending balance \| shares	13,293
Options Outstanding, Options exercisable \| shares	4,728
Options Outstanding, Options vested and expected to vest \| shares	12,752
Weighted Average Exercise Price, Beginning balance \| $ / shares	$ 10.85
Weighted Average Exercise Price, Granted \| $ / shares	1.25
Weighted Average Exercise Price, Exercised \| $ / shares	0.97
Weighted Average Exercise Price, Expired \| $ / shares	82.85
Weighted Average Exercise Price, Forfeited \| $ / shares	14.87
Weighted Average Exercise Price, Ending balance \| $ / shares	6.67
Weighted Average Exercise Price, Options exercisable \| $ / shares	13.15
Weighted Average Exercise Price, Options vested and expected to vest \| $ / shares	$ 6.86

Stock-Based Compensation - Summary of RSU Activity Under 2018 Plan (Details) - $ / shares	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Time-based Restricted Stock Units
Number of Shares
Balance at December 31, 2023	5,621,000
Granted	3,719,000
Vested	(670,000)
Forfeited/cancelled	(1,378,000)
Balance at March 31, 2024	7,292,000
Weighted-Average Grant Date Fair Value
Balance at December 31, 2023	$ 10.16
Granted	1.25	$ 7.2
Vested	11.47
Forfeited/cancelled	10.45
Balance at March 31, 2024	$ 5.44
Performance-based Restricted Stock Units
Number of Shares
Balance at December 31, 2023	2,845,000
Forfeited/cancelled	(2,845,000)
Balance at March 31, 2024	0
Weighted-Average Grant Date Fair Value
Balance at December 31, 2023	$ 6.3
Forfeited/cancelled	6.3
Balance at March 31, 2024	$ 0

Stock-Based Compensation - Summary of Weighted-Average Assumptions Used to Calculate Fair Value of Stock Options Granted (Details)	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Risk-free interest rate	4.28%	3.65%
Expected volatility	101.27%	95.86%
Expected dividend yield	0.00%	0.00%
Expected term (in years)	5 years 4 months 28 days	6 years 29 days

- Definition

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

+ References

+ Details

Stockholders' Equity - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Aug. 04, 2022	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Class of Stock [Line Items]
Common stock, par value		$ 0.001		$ 0.001
Aggregate net proceeds		$ 0	$ 990
At-the-Market Equity Offering
Class of Stock [Line Items]
Sale of stock, average price per share			$ 7.2
Aggregate amount available to be sold under sales agreement	$ 75,000
Commission rate	3.00%
Amount of securities offered under S-3 registartion statement	$ 250,000
Proceeds from sale of common stock, net of commission			$ 1,000
Common stock sold (in Shares)		0	100,000
Common stock available for sale		$ 74,000

Investments - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities in an unrealized loss position, fair value	$ 81.0		$ 53.7
Available for sale securities gross realized gains or losses on sale or maturity	$ 0.0	$ 0.0
Maximum
Schedule Of Available For Sale Securities [Line Items]
Available-for-sale securities, remaining maturity period	1 year

- Definition

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

+ References

+ Details

Defined Contribution Plans - Additional Information (Details) - 401(K) Plan - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Defined Contribution Plan Disclosure [Line Items]
Contributions made by employer	$ 0.5	$ 0.5
Maximum
Defined Contribution Plan Disclosure [Line Items]
Employer contribution matching percentage	4.00%

BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Current assets:
Cash and cash equivalents	$ 43,060	$ 66,440
Investments	96,192	104,354
Prepaid expenses and other current assets	8,382	9,095
Total current assets	147,634	179,889
Property and equipment, net	17,364	33,369
Operating lease right-of-use assets	10,577	24,136
Other long-term assets	1,737	6,216
Total assets	177,312	243,610
Current liabilities:
Accounts payable	15,748	1,764
Accrued expenses and other current liabilities	20,173	34,814
Total current liabilities	35,921	36,578
Operating lease liabilities, net of current portion	37,408	38,215
Total liabilities	73,329	74,793
Contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 20,000 shares authorized as of March 31, 2024 and December 31, 2023; no shares issued and outstanding as of March 31, 2024 and December 31, 2023	0	0
Common stock, $0.001 par value per share; 200,000 shares authorized as of March 31, 2024 and December 31, 2023; 88,544 and 87,750 shares issued and outstanding as of March 31, 2024 and December 31, 2023, respectively	89	88
Additional paid-in capital	1,293,497	1,287,156
Accumulated other comprehensive gain (loss)	20	50
Accumulated deficit	(1,189,623)	(1,118,477)
Total stockholders’ equity	103,983	168,817
Total liabilities and stockholders’ equity	$ 177,312	$ 243,610