0001619856-24-000081 | 10-Q | XBRL Viewer

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Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2024
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Since December 31, 2023, there have been no new related party transactions, except as set forth below. For further information regarding our related parties, see Note 7 to the consolidated financial statements included in our Form 10-K. Pfizer Investment During the three months ended September 30, 2024, we recognized $0.6 million of revenue from our Information Rights Agreement with Pfizer, dated June 29, 2023, pursuant to which we had originally allocated $7.5 million as a contract with a customer under ASC Topic 606. During the nine months ended September 30, 2024, we recognized $1.9 million of revenue from Pfizer. During each of the three- and nine-month periods ended September 30, 2023, we recognized $0.6 million of revenue from Pfizer. As of September 30, 2024, there was approximately $4.4 million of related party deferred revenue ($2.5 million included in current liabilities and $1.9 million included in long-term liabilities) related to our performance obligation to Pfizer. As of December 31, 2023, there was approximately $6.2 million of related party deferred revenue ($2.5 million included in current liabilities and $3.7 million included in long-term liabilities) related to our performance obligation to Pfizer. Edge Animal Health In June 2024, we received additional shares of convertible preferred stock pursuant to anti-dilution rights associated with the Exclusive License Agreement for Veterinary Therapeutics (as amended, “Edge chRDNA License Agreement”) with Edge Animal Health (“Edge”), a private company and related party. Edge issued 1,623,275 shares of convertible preferred stock to us with an estimated fair value of $1.6 million, based on management’s best estimate and judgment. The Edge chRDNA License Agreement is a contract with a customer under ASC 606. We did not recognize any revenue in connection with the Edge chRDNA License Agreement during the three months ended September 30, 2024. We recognized $1.6 million as revenue during the nine months ended September 30, 2024. We did not recognize any revenue in connection with the Edge chRDNA License Agreement in 2023. On May 16, 2023, we entered into an Exclusive License Agreement for Veterinary Therapeutics (CRISPR-Cas9) (“Edge Cas9 License Agreement”), under which we granted Edge an exclusive worldwide license to certain CRISPR-Cas9 intellectual property rights in the field of veterinary therapeutics. Previously, on May 15, 2020, we entered into an Option for an Exclusive License under which Edge could exercise its option within three years upon payment of a total of $1.2 million, which option Edge exercised and paid $1.2 million, and we entered into the Edge Cas9 License Agreement. We did not recognize any revenue in connection with the Edge Cas9 License Agreement in 2024. We did not recognize any revenue in connection with the Edge Cas9 License Agreement during the three months ended September 30, 2023. We recognized $1.2 million of revenue in connection with the Edge Cas9 License Agreement during the nine months ended September 30, 2023.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

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+ Details

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Pay vs Performance Disclosure
Net loss	$ (34,684)	$ (37,697)	$ (41,234)	$ (10,002)	$ (29,519)	$ (28,044)	$ (113,615)	$ (67,565)

- Definition

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

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+ Details

Related Party Transactions (Details) - USD ($)		1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
Related Party Transactions (Details) - USD ($)	May 15, 2020	Jun. 30, 2024	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	May 16, 2024	Jun. 29, 2023
Related Party Transaction [Line Items]
Revenue			$ 2,024,000	$ 23,662,000	$ 7,917,000	$ 30,919,000
Deferred revenue			6,776,000		6,776,000		$ 8,949,000
Deferred revenue, current			2,829,000		2,829,000		2,847,000
Deferred revenue, noncurrent			3,947,000		3,947,000		6,102,000
Pfizer
Related Party Transaction [Line Items]
Revenue			600,000
Pfizer \| Related Party
Related Party Transaction [Line Items]
Revenue				600,000	1,900,000	600,000
Deferred revenue			4,400,000		4,400,000		6,200,000		$ 7,500,000
Deferred revenue, current			2,500,000		2,500,000		2,500,000
Deferred revenue, noncurrent			1,900,000		1,900,000		3,700,000
Edge Animal Health
Related Party Transaction [Line Items]
Revenue			$ 0		1,600,000		$ 0
Edge Animal Health \| Convertible Preferred Stock
Related Party Transaction [Line Items]
Convertible preferred stock issued (in shares)		1,623,275
Fair value of convertible preferred stock		$ 1,600,000
Edge Cas9 License Agreement
Related Party Transaction [Line Items]
Revenue	$ 1,200,000			$ 0	$ 0	$ 1,200,000
Exercise option, term								3 years

Common Stock (Details) - USD ($) $ / shares in Units, $ in Millions		2 Months Ended	9 Months Ended
	Aug. 09, 2022	Aug. 31, 2023	Sep. 30, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			21,881,496	17,084,128
Authorized amount under shelf registration	$ 400.0
At The Market ATM Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate offering price (up to)			$ 12.3
Common stock shares sold (in shares)			1,762,806
Public offering price (in dollars per share)			$ 7.32
Aggregate gross proceeds			$ 12.9
At The Market ATM Offering \| Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate offering price (up to)	$ 100.0
Public Stock Offering
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Aggregate offering price (up to)		$ 134.4
Common stock shares sold (in shares)		22,115,384
Public offering price (in dollars per share)		$ 6.50
Aggregate gross proceeds		$ 143.7
Over-Allotment Option
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock shares sold (in shares)		2,884,615
Stock options, issued and outstanding
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			11,611,364	9,410,404
Stock options, authorized for future issuances
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			6,827,620	5,952,012
Stock available under ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			2,139,666	1,516,355
Unvested RSUs and PSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)			1,302,846	205,357

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	At-The-Market Offering, Net of Offering Expense	Private Placement	Follow-Up Offering, Net of Operating Expense	Common Stock	Common Stock At-The-Market Offering, Net of Offering Expense	Common Stock Private Placement	Common Stock Follow-Up Offering, Net of Operating Expense	Additional Paid-In Capital	Additional Paid-In Capital At-The-Market Offering, Net of Offering Expense	Additional Paid-In Capital Private Placement	Additional Paid-In Capital Follow-Up Offering, Net of Operating Expense	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2022					61,029,184
Beginning balance at Dec. 31, 2022	$ 300,871				$ 6				$ 499,598				$ (1,518)	$ (197,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock under ESPP (in shares)					70,271
Issuances of common stock under ESPP	404								404
Issuances of common stock on exercises of options (in shares)					55,433
Issuances of common stock on exercises of options	115								115
Issuances of common stock (in shares)						168,635
Issuances of common stock during different pursuits		$ 1,007								$ 1,007
Stock-based compensation expense	3,131								3,131
Net loss	(28,044)													(28,044)
Other comprehensive income (loss)	788												788
Ending balance (in shares) at Mar. 31, 2023					61,323,523
Ending balance at Mar. 31, 2023	278,272				$ 6				504,255				(730)	(225,259)
Beginning balance (in shares) at Dec. 31, 2022					61,029,184
Beginning balance at Dec. 31, 2022	300,871				$ 6				499,598				(1,518)	(197,215)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(67,565)
Ending balance (in shares) at Sep. 30, 2023					88,430,609
Ending balance at Sep. 30, 2023	398,268				$ 8				664,021				(981)	(264,780)
Beginning balance (in shares) at Mar. 31, 2023					61,323,523
Beginning balance at Mar. 31, 2023	278,272				$ 6				504,255				(730)	(225,259)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock on exercises of options (in shares)					86,085
Issuances of common stock on exercises of options	236								236
Issuances of common stock (in shares)							4,690,431
Issuances of common stock during different pursuits			$ 17,290								$ 17,290
Stock-based compensation expense	3,585								3,585
Net loss	(29,519)													(29,519)
Other comprehensive income (loss)	(406)												(406)
Ending balance (in shares) at Jun. 30, 2023					66,100,039
Ending balance at Jun. 30, 2023	269,458				$ 6				525,366				(1,136)	(254,778)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock under ESPP (in shares)					68,183
Issuances of common stock under ESPP	382								382
Issuances of common stock on exercises of options (in shares)					83,407
Issuances of common stock on exercises of options	372								372
Issuances of common stock (in shares)								22,115,384
Issuances of common stock during different pursuits				$ 134,425				$ 2				$ 134,423
Issuances of common stock on RSU release (in shares)					63,596
Stock-based compensation expense	3,478								3,478
Net loss	(10,002)													(10,002)
Other comprehensive income (loss)	155												155
Ending balance (in shares) at Sep. 30, 2023					88,430,609
Ending balance at Sep. 30, 2023	398,268				$ 8				664,021				(981)	(264,780)
Beginning balance (in shares) at Dec. 31, 2023					88,448,948
Beginning balance at Dec. 31, 2023	368,401				$ 8				667,648				30	(299,285)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock under ESPP (in shares)					122,035
Issuances of common stock under ESPP	667								667
Issuances of common stock on exercises of options (in shares)					134,347
Issuances of common stock on exercises of options	489								489
Issuances of common stock (in shares)						1,594,171
Issuances of common stock during different pursuits		$ 11,330				$ 1				$ 11,329
Issuances of common stock on RSU release (in shares)					15,000
Stock-based compensation expense	3,988								3,988
Net loss	(41,234)													(41,234)
Other comprehensive income (loss)	(352)												(352)
Ending balance (in shares) at Mar. 31, 2024					90,314,501
Ending balance at Mar. 31, 2024	343,289				$ 9				684,121				(322)	(340,519)
Beginning balance (in shares) at Dec. 31, 2023					88,448,948
Beginning balance at Dec. 31, 2023	$ 368,401				$ 8				667,648				30	(299,285)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock on exercises of options (in shares)	182,217
Net loss	$ (113,615)
Ending balance (in shares) at Sep. 30, 2024					90,552,687
Ending balance at Sep. 30, 2024	281,203				$ 9				693,305				789	(412,900)
Beginning balance (in shares) at Mar. 31, 2024					90,314,501
Beginning balance at Mar. 31, 2024	343,289				$ 9				684,121				(322)	(340,519)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock under ESPP (in shares)					400
Issuances of common stock under ESPP	2								2
Issuances of common stock on exercises of options (in shares)					47,870
Issuances of common stock on exercises of options	129								129
Stock-based compensation expense	4,738								4,738
Net loss	(37,697)													(37,697)
Other comprehensive income (loss)	3												3
Ending balance (in shares) at Jun. 30, 2024					90,362,771
Ending balance at Jun. 30, 2024	310,464				$ 9				688,990				(319)	(378,216)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of common stock under ESPP (in shares)					138,743
Issuances of common stock under ESPP	246								246
Issuances of common stock on RSU release (in shares)					51,173
Stock-based compensation expense	4,069								4,069
Net loss	(34,684)													(34,684)
Other comprehensive income (loss)	1,108												1,108
Ending balance (in shares) at Sep. 30, 2024					90,552,687
Ending balance at Sep. 30, 2024	$ 281,203				$ 9				$ 693,305				$ 789	$ (412,900)

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2024
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes No income tax expense was recorded during each of the three- and nine-month periods ended September 30, 2024, and 2023 due to our operating losses.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
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-Name Accounting Standards Codification
-Section 50
-Paragraph 12
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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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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-SubTopic 10
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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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-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Leases - Additional Information (Details)	Sep. 30, 2024 ft²
Commitments and Contingencies Disclosure [Abstract]
Area of real estate property (in square feet)	75,000
Remaining lease term (in years)	7 years 9 months 18 days
Lease renewal term (in years)	5 years

Net Loss Per Share (Tables)

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Schedule of Basic and Diluted Net Income Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share amounts):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Numerator:
Net loss	$	(34,684)	$	(10,002)	$	(113,615)	$	(67,565)
Denominator:
Weighted-average common shares outstanding used to compute net loss per share, basic and diluted	90,455,900		83,783,992		90,034,799		68,878,921
Net loss per share, basic and diluted	$	(0.38)	$	(0.12)	$	(1.26)	$	(0.98)

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share

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


	As of September 30, 2024	As of September 30, 2023
Stock options outstanding	11,611,364	9,523,394
RSUs issued and outstanding	1,259,377	168,438
Shares committed under ESPP	304,434	134,276
	13,175,175	9,826,108

Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended
Income Taxes (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0	$ 0	$ 0

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
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+ Details

Stock-Based Compensation - Schedule of Restricted Stock Units Activity (RSUs) (Details) - Restricted Stock Units RSU and Performance-Based RSUs	9 Months Ended
	Sep. 30, 2024 $ / shares shares
Number of Shares Underlying Outstanding RSUs and PSUs
Unvested, beginning of period (in shares) \| shares	205,357
Granted (in shares) \| shares	1,342,842
Vested (in shares) \| shares	(66,173)
Forfeited (in shares) \| shares	(179,180)
Unvested, end of period (in shares) \| shares	1,302,846
Weighted-Average Grant Date Fair Value per RSU and PSU
Unvested, Weighted-Average Grant Date Fair Value per RSU, Beginning Balance (in dollars per share) \| $ / shares	$ 8.49
Granted, Weighted-Average Grant Date Fair Value per RSU (in dollars per share) \| $ / shares	5.71
Vested, Weighted-Average Grant Date Fair Value per RSU and PRSU (in dollars per share) \| $ / shares	10.07
Forfeited, Weighted-Average Grant Date Fair Value per RSU and PRSU (in dollars per share) \| $ / shares	7.17
Unvested, Weighted-Average Grant Date Fair Value per RSU, Ending Balance (in dollars per share) \| $ / shares	$ 5.73

Common Stock

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Common Stock

Common stock reserved for future issuances consisted of the following:


	As of September 30, 2024	As of December 31, 2023
Stock options, issued and outstanding	11,611,364	9,410,404
Stock options, authorized for future issuances	6,827,620	5,952,012
Stock available under ESPP	2,139,666	1,516,355
Unvested RSUs and PSUs	1,302,846	205,357
Total common stock reserved for future issuances	21,881,496	17,084,128

Shelf Registration Statement

On August 9, 2022, we filed a shelf registration statement on Form S-3 (“Shelf Registration Statement”) with the SEC. The Shelf Registration Statement allows us to sell from time to time up to $400.0 million of common stock, preferred stock, debt securities, warrants, rights, or units comprised of any combination of these securities, for our own account in one or more offerings (including the $100.0 million of common stock reserved for our at-the-market equity offering program). The SEC declared the Shelf Registration Statement effective on August 16, 2022. The terms of any offering under the Shelf Registration Statement will be established at the time of such offering, as described in a prospectus supplement to the Shelf Registration Statement to be filed with the SEC prior to the completion of any such offering.

In July and August 2023, we issued and sold a total of 22,115,384 shares of our common stock in an underwritten follow-on public offering at a price to the public of $6.50 per share, which included the full exercise of the underwriters’ right to purchase 2,884,615 additional shares of our common stock. The total gross proceeds from the offering were approximately $143.7 million ($134.4 million net of underwriting discounts and commissions and offering expenses). The shares were issued pursuant to the Shelf Registration Statement.

At-the-market Equity Offering Program

On August 9, 2022, we entered into an at-the-market Open Market Sale AgreementSM (“ATM Sales Agreement”) with Jefferies LLC (“Jefferies”), pursuant to which, through Jefferies as sales agent, we may from time to time, sell shares of our common stock having an aggregate offering price of up to $100.0 million in gross proceeds under the Shelf Registration Statement. As of September 30, 2024, we have sold 1,762,806 shares of our common stock under the ATM Sales Agreement, at an average price per share of $7.32 for aggregate gross proceeds of $12.9 million ($12.3 million net of offering expenses).

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Change in Fair Value of Financial Liability (Details) - MSKCC success payments liability - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Change in fair value	$ 200	$ (100)	$ (1,900)	$ (400)
Level 3
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Balance at December 31, 2023			2,939
Change in fair value			(1,934)
Balance at September 30, 2024	$ 1,005		$ 1,005

Stock-Based Compensation - Schedule of Stock Option Expenses Related to Employee and Non-Employee Stock Options Granted (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 4,069	$ 3,478	$ 12,795	$ 10,194
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	1,638	1,464	5,248	4,324
General and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 2,431	$ 2,014	$ 7,547	$ 5,870

Balance Sheet Items

9 Months Ended

Sep. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Balance Sheet Items

Other receivables consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Patent cost reimbursements	$	936	$	1,403
Accrued interest on marketable securities	747		702
Other	—		181
Total	$	1,683	$	2,286

Prepaid expenses and other current assets consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Prepaid contract manufacturing and clinical costs	$	3,279	$	3,942
Prepaid insurance	1,100		993
Other	2,204		1,220
Total	$	6,583	$	6,155

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


	September 30, 2024		December 31, 2023
Lab equipment	$	18,276	$	15,581
Leasehold improvements	11,493		2,235
Computer equipment	906		895
Furniture and equipment	697		499
Construction in progress	—		8,204
Total property and equipment, gross	31,372		27,414
Less: accumulated depreciation and amortization	(11,807)		(9,144)
Property and equipment, net	$	19,565	$	18,270

Depreciation and amortization expenses related to property and equipment were $1.1 million and $1.6 million for the three months ended September 30, 2024, and 2023, respectively. Depreciation and amortization expenses related to property and equipment were $2.7 million and $2.8 million, for the nine months ended September 30, 2024, and 2023, respectively.

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


	September 30, 2024		December 31, 2023
Accrued research and development expenses	$	12,150	$	8,720
Accrued employee compensation and related expenses	7,087		9,517
Accrued securities litigation settlement	3,900		—
Accrued patent expenses	839		613
Accrued expenses related to sublicensing revenues	483		802
Credit card liability	16		377
Other	973		1,106
Total	$	25,448	$	21,135

Balance Sheet Items - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Accrued research and development expenses	$ 12,150	$ 8,720
Accrued employee compensation and related expenses	7,087	9,517
Accrued securities litigation settlement	3,900	0
Accrued patent expenses	839	613
Accrued expenses related to sublicensing revenues	483	802
Credit card liability	16	377
Other	973	1,106
Total	$ 25,448	$ 21,135

Balance Sheet Items (Tables)

9 Months Ended

Sep. 30, 2024

Balance Sheet Related Disclosures [Abstract]

Schedule of Other Receivables

Other receivables consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Patent cost reimbursements	$	936	$	1,403
Accrued interest on marketable securities	747		702
Other	—		181
Total	$	1,683	$	2,286

Schedule of Prepaid Expenses and Other Current Assets

Prepaid expenses and other current assets consisted of the following (in thousands):


	September 30, 2024		December 31, 2023
Prepaid contract manufacturing and clinical costs	$	3,279	$	3,942
Prepaid insurance	1,100		993
Other	2,204		1,220
Total	$	6,583	$	6,155

Schedule of Property and Equipment

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


	September 30, 2024		December 31, 2023
Lab equipment	$	18,276	$	15,581
Leasehold improvements	11,493		2,235
Computer equipment	906		895
Furniture and equipment	697		499
Construction in progress	—		8,204
Total property and equipment, gross	31,372		27,414
Less: accumulated depreciation and amortization	(11,807)		(9,144)
Property and equipment, net	$	19,565	$	18,270

Schedule of Accrued Expenses and Other Current Liabilities

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


	September 30, 2024		December 31, 2023
Accrued research and development expenses	$	12,150	$	8,720
Accrued employee compensation and related expenses	7,087		9,517
Accrued securities litigation settlement	3,900		—
Accrued patent expenses	839		613
Accrued expenses related to sublicensing revenues	483		802
Credit card liability	16		377
Other	973		1,106
Total	$	25,448	$	21,135

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Schedule of Provision for Credit Losses and Other Uncertainties

Licensees that represent 10% or more of our revenue and accounts receivable and contract assets were as follows:


	Revenue				Revenue				Accounts Receivable and Contract Assets
	Three Months Ended				Nine Months Ended				As of September 30, 2024		As of December 31, 2023
	September 30, 2024		September 30, 2023		September 30, 2024		September 30, 2023
Licensee A	34.9	%	*		24.2	%	*		68.5	%	47.5	%
Licensee B	*		90.8	%	*		79.1	%	*		*
Licensee C	30.7	%	*		23.6	%	*		*		*
Licensee D	*		*		20.5	%	*		*		*
Licensee E	14.0	%	*		*		*		*		*
Licensee F	11.2	%	*		*		*		*		*
Licensee G	*		*		*		*		15.9	%	*
Total	90.8	%	90.8	%	68.3	%	79.1	%	84.4	%	47.5	%

*Less than 10%

Description of the Business, Organization, and Liquidity	9 Months Ended
	Sep. 30, 2024
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of the Business, Organization, and Liquidity	Description of the Business, Organization, and Liquidity Business and Organization Caribou Biosciences, Inc. (“Company” or “we”) is a clinical-stage Clustered Regularly Interspaced Short Palindromic Repeats (“CRISPR”) genome-editing biopharmaceutical company dedicated to developing transformative therapies for patients with devastating diseases. Our genome-editing platform, including our novel chRDNA (CRISPR hybrid RNA-DNA, or “chRDNA,” pronounced “chardonnay”) technology, enables more precise genome editing to develop cell therapies that are armored to improve activity against diseases. We are advancing a pipeline of allogeneic, or off-the-shelf, cell therapies from our chimeric antigen receptor (“CAR”) T (“CAR-T”) cell platform as readily available therapeutic treatments for patients. We incorporated in October 2011 as a Delaware corporation and are headquartered in Berkeley, California. We have four wholly owned subsidiaries: Antler Holdco, LLC, incorporated in Delaware in April 2019; Microbe Holdco, LLC, incorporated in Delaware in June 2020; Arboreal Holdco, LLC, incorporated in Delaware in November 2020; and Biloba Holdco, LLC, incorporated in Delaware in April 2021. Our wholly owned subsidiaries hold interests in our equity investments and do not have operating activities. Liquidity We have incurred operating losses and negative cash flows from operations since our inception and we had an accumulated deficit of $412.9 million as of September 30, 2024. During the nine months ended September 30, 2024, we incurred a net loss of $113.6 million and used $102.7 million of cash in operating activities. We expect to continue to incur substantial losses, and our ability to achieve and sustain profitability will depend on the successful development, regulatory approval, and commercialization of our product candidates and on our ability to generate sufficient revenue to support our cost structure. We may never achieve profitability and, unless and until we do, we will need to continue to raise additional capital. Our management expects that existing cash, cash equivalents, and marketable securities of $281.0 million as of September 30, 2024, will be sufficient to fund our current operating plan for at least the next 12 months from the date of this Quarterly Report on Form 10-Q (“Form 10-Q”).

Significant Agreements (Details) - USD ($)	3 Months Ended		9 Months Ended
Significant Agreements (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	$ 30,421,000	$ 28,584,000	$ 99,689,000	$ 80,796,000
General and administrative	9,841,000	9,711,000	35,969,000	28,740,000
Future payments for milestones	159,900,000		159,900,000
Collaboration and License Agreement with AbbVie
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenues	0	21,500,000	0	24,500,000
Intellia Therapeutics, Inc.
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	200,000	400,000	1,800,000	1,200,000
General and administrative	100,000	400,000	500,000	2,200,000
Intellia Therapeutics, Inc. \| Patents
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reduction in general and administrative expenses	$ 400,000	$ 100,000	$ 900,000	$ 1,300,000

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

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+ Details

Stock-Based Compensation - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended		35 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	21,881,496		21,881,496			17,084,128
Stock options granted during period (in shares)			3,528,702
Unrecognized stock based-compensation expenses	$ 24.5		$ 24.5
Weighted-average period (in years)			2 years 7 months 6 days
RSUs
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average period (in years)			2 years 10 months 24 days
Unrecognized stock-based compensation expense, excluding options	5.7		$ 5.7
Performance Shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unrecognized stock based-compensation expenses	$ 0.4		$ 0.4
Shares committed under ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	2,139,666		2,139,666			1,516,355
Accrued liabilities	$ 0.1		$ 0.1
Employee
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock options granted during period (in shares)	391,525	384,095	3,528,702	3,406,801
Weighted average grant date fair value (in dollars per share)	$ 1.49	$ 3.64	$ 4.09	$ 3.91
2021 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	6,827,620		6,827,620
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Issuance of common stock in connection with our ATM offering, net of offering expenses (in shares)					468,745

Description of the Business, Organization, and Liquidity (Details) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2024 USD ($) subsidiary	Sep. 30, 2023 USD ($)	Dec. 31, 2023 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of subsidiaries \| subsidiary							4
Accumulated deficit	$ (412,900)						$ (412,900)		$ (299,285)
Net loss	(34,684)	$ (37,697)	$ (41,234)	$ (10,002)	$ (29,519)	$ (28,044)	(113,615)	$ (67,565)
Cash generated in operating activities							(102,730)	$ (71,912)
Cash, cash equivalents and short term marketable securities	$ 281,000						$ 281,000

- 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

Fair Value Measurements and Fair Value of Financial Instruments - Additional Information (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2023
Fair value of common stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	1.96		1.96		5.73
MSKCC success payments liability
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Change in fair value	$ (0.2)	$ 0.1	$ 1.9	$ 0.4

Fair Value Measurements and Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Schedule of Financial Instruments Measured on Recurring Basis

The following table sets forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	Fair Value Measurements as of September 30, 2024
	Total		Level 1		Level 2		Level 3
Assets:
U.S. Treasury bills ($5,596 included in cash and cash equivalents)	$	193,812	$	193,812	$	—	$	—
U.S. government agency bonds ($3,973 included in cash and cash equivalents)	31,515		—		31,515		—
Commercial paper ($5,990 included in cash and cash equivalents)	30,203		—		30,203		—
Money market fund investments (included in cash and cash equivalents)	16,411		16,411		—		—
Corporate debt securities	9,074		—		9,074		—
Total fair value of assets	$	281,015	$	210,223	$	70,792	$	—
Liabilities:
MSKCC success payments liability	$	1,005	$	—	$	—	$	1,005
Total fair value of liabilities	$	1,005	$	—	$	—	$	1,005


	Fair Value Measurements as of December 31, 2023
	Total		Level 1		Level 2		Level 3
Assets:
U.S. Treasury bills ($23,527 included in cash and cash equivalents)	$	262,439	$	262,439	$	—	$	—
Commercial paper ($9,759 included in cash and cash equivalents)	40,373		—		40,373		—
U.S. government agency bonds	40,185		—		40,185		—
Money market fund investments (included in cash and cash equivalents)	17,876		17,876		—		—
Corporate debt securities	11,531		—		11,531		—
Total fair value of assets	$	372,404	$	280,315	$	92,089	$	—
Liabilities:
MSKCC success payments liability	$	2,939	$	—	$	—	$	2,939
Total fair value of liabilities	$	2,939	$	—	$	—	$	2,939

Schedule of Fair Value and Amortized Cost of Cash Equivalents and Available-for-Sale Marketable Securities

The fair value and amortized cost of cash equivalents and available-for-sale marketable securities by major security type as of September 30, 2024, and December 31, 2023, are presented in the following tables (in thousands):


	As of September 30, 2024
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury bills ($5,596 included in cash and cash equivalents)	$	193,198	$	617	$	(3)	$	193,812
U.S. government agency bonds ($3,973 included in cash and cash equivalents)	31,380		136		(1)		31,515
Commercial paper ($5,990 included in cash and cash equivalents)	30,173		32		(2)		30,203
Money market fund investments (included in cash equivalents)	16,411		—		—		16,411
Corporate debt securities	9,064		10		—		9,074
Total cash equivalents and marketable securities	$	280,226	$	795	$	(6)	$	281,015

Classified as:
Cash and cash equivalents							$	31,970
Marketable securities, short-term							196,208
Marketable securities, long-term							52,837
Total cash equivalents and marketable securities							$	281,015


	As of December 31, 2023
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury bills ($23,527 included in cash and cash equivalents)	$	262,328	$	331	$	(220)	$	262,439
Commercial paper ($9,759 included in cash and cash equivalents)	40,386		—		(13)		40,373
U.S. government agency bonds	40,295		1		(111)		40,185
Money market fund investments (included in cash equivalents)	17,876		—		—		17,876
Corporate debt securities	11,489		50		(8)		11,531
Total cash equivalents and marketable securities	$	372,374	$	382	$	(352)	$	372,404

Classified as:
Cash and cash equivalents							$	51,162
Marketable securities, short-term							277,665
Marketable securities, long-term							43,577
Total cash equivalents and marketable securities							$	372,404

Schedule of Investments Classified by Contractual Maturity Date

The following table presents the fair value of available-for-sale marketable securities by contractual maturities (in thousands):


	September 30, 2024
Due in less than one year	$	196,208
Due in one to five years	52,837
Total	$	249,045

Schedule of Change in Fair Value of Financial Liability

The following table sets forth a summary of the changes in the fair value of our Level 3 financial liability (in thousands):


	MSKCC Success Payments Liability
Balance at December 31, 2023	$	2,939
Change in fair value	(1,934)
Balance at September 30, 2024	$	1,005

Schedule of Assumptions Used in Valuation of MSKCC Success Payments Liability

The table below summarizes key assumptions used in the valuation of the MSKCC success payments liability:


	As of December 31, 2023
Fair value of common stock	$	5.73
Risk-free interest rate	3.88%
Expected volatility	79%
Probability of achieving multiple of Initial Share Price(1)	5.2% to 18.1%
Expected term (years)	3.7 to 5.2

(1)MSKCC is entitled to certain success payments if our common stock fair value increases, during a specified time period, by certain multiples of value based on a comparison of the fair market value of our common stock to $5.1914 per share, adjusted for any future stock splits (“Initial Share Price”). For further information regarding our agreement with MSKCC, see Note 4 to the consolidated financial statements included in our Form 10-K.

Significant Agreements	9 Months Ended
Significant Agreements	Sep. 30, 2024
Significant Agreements [Abstract]
Significant Agreements	Significant Agreements Since December 31, 2023, there have been no material changes to the key terms of our significant agreements. For further information regarding our significant agreements, see Note 4 to the consolidated financial statements included in our Form 10-K. During the three months ended September 30, 2023, we recognized $21.5 million in revenue associated with the now-terminated Collaboration and License Agreement, dated February 9, 2021 (as amended, “AbbVie Agreement”) with AbbVie Manufacturing Management Unlimited Company (“AbbVie”). During the nine months ended September 30, 2023, we recognized $24.5 million in revenue under the AbbVie Agreement. No revenue was recognized under the AbbVie Agreement during each of the three- and nine-month periods ended September 30, 2024, as the AbbVie Agreement was terminated effective October 25, 2023. As of September 30, 2024, and December 31, 2023, we had no amounts recorded in accounts receivable, contract assets, or deferred revenue in our consolidated balance sheets related to the AbbVie Agreement. Our significant agreements may include nonrefundable, upfront payments; annual license maintenance fees; sublicensing fees; obligations to reimburse for patent prosecution and maintenance fees; success payments; regulatory clinical and commercial milestones; and royalty payments. Our obligation to make such payments is contingent upon milestones being achieved, licensed products being commercialized, and the agreements remaining in effect. For the three months ended September 30, 2024, and 2023, we recorded $0.2 million and $0.4 million, respectively, as research and development expense in our unaudited condensed consolidated statements of operations and comprehensive loss related to our license agreements. For the nine months ended September 30, 2024, and 2023, we recorded $1.8 million and $1.2 million, respectively, as research and development expense in our unaudited condensed consolidated statements of operations and comprehensive loss related to our significant agreements. For the three months ended September 30, 2024, and 2023, we recorded $0.1 million and $0.4 million, respectively, as general and administrative expense for patent prosecution and maintenance costs in our unaudited condensed consolidated statements of operations and comprehensive loss, which includes reimbursements of patent prosecution and maintenance costs of $0.4 million and $0.1 million, respectively. For the nine months ended September 30, 2024, and 2023, we recorded $0.5 million and $2.2 million, respectively, as general and administrative expense for patent prosecution and maintenance costs in our unaudited condensed consolidated statements of operations and comprehensive loss, which includes reimbursements of patent prosecution and maintenance costs of $0.9 million and $1.3 million, respectively. As of September 30, 2024, certain license and assignment agreements included potential future payments from us for development, regulatory, and sales milestones totaling approximately $159.9 million.

Leases (Tables)

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Schedule of Components Lease Cost

The components of lease costs, which are included in our unaudited condensed consolidated statements of operations and comprehensive loss, were as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Operating lease cost(1)	$	1,950	$	1,937	$	5,822	$	5,749
Short-term lease cost	63		63		188		188
Total lease cost	$	2,013	$	2,000	$	6,010	$	5,937

(1)Includes $0.7 million of variable lease cost related to operating expenses and taxes for each of the three- month periods ended September 30, 2024, and September 30, 2023. Includes $2.0 million and $1.9 million of variable lease cost related to operating expenses and taxes for the nine months ended September 30, 2024, and 2023, respectively.

Schedule of Supplemental Information Related to Leases

Supplemental information related to our leases was as follows (in thousands):


	Nine Months Ended September 30,
	2024		2023
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	2,624	$	2,597

The following table summarizes the weighted-average remaining lease term and weighted-average discount rate for our corporate laboratory and office leases:


	September 30, 2024		December 31, 2023
Weighted-average remaining lease term (years)	6.7		7.4
Weighted-average discount rate	11.3	%	11.3	%

Schedule of Future Minimum Lease Payment Under Leases

The following table summarizes a maturity analysis of our operating lease liabilities showing the aggregate lease payments as of September 30, 2024 (in thousands):


Remainder of 2024(1)	$	797
2025	4,411
2026	5,720
2027	5,922
2028	6,122
Thereafter	15,993
Total future undiscounted lease payments	38,965
Less imputed interest	(12,324)
Total discounted lease payments	26,641
Less current portion of lease liability	(1,178)
Noncurrent portion of lease liability	$	25,463

(1)Reflects an offset of $0.3 million related to incentives expected to be received in 2024.

Revenue - Remaining Performance Obligations (Details) $ in Millions	Sep. 30, 2024 USD ($)
Disaggregation Of Revenue [Line Items]
Remaining performance obligations	$ 6.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-10-01
Disaggregation Of Revenue [Line Items]
Remaining performance obligations	$ 2.8
Remaining performance obligation, expected timing of satisfaction, period	12 months

- 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

Commitments and Contingencies (Details) $ in Millions	3 Months Ended
Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2024 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Litigation settlement, amount awarded to other party	$ 3.9

Net Loss Per Share

9 Months Ended

Sep. 30, 2024

Earnings Per Share [Abstract]

Net Loss Per Share

The following table sets forth the computation of the basic and diluted net loss per share (in thousands, except share and per share amounts):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Numerator:
Net loss	$	(34,684)	$	(10,002)	$	(113,615)	$	(67,565)
Denominator:
Weighted-average common shares outstanding used to compute net loss per share, basic and diluted	90,455,900		83,783,992		90,034,799		68,878,921
Net loss per share, basic and diluted	$	(0.38)	$	(0.12)	$	(1.26)	$	(0.98)

Because we were in a net loss position for all periods presented, basic net loss per share is the same as diluted net loss per share for all periods, as the inclusion of all common stock equivalents outstanding would have been anti-dilutive. Potentially dilutive securities that were not included in the diluted per share calculations because they would be anti-dilutive were as follows:


	As of September 30, 2024	As of September 30, 2023
Stock options outstanding	11,611,364	9,523,394
RSUs issued and outstanding	1,259,377	168,438
Shares committed under ESPP	304,434	134,276
	13,175,175	9,826,108

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Deferred revenue, current	$ 2,829	$ 2,847
Deferred revenue, noncurrent	$ 3,947	$ 6,102
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares outstanding (in shares)	90,552,687	88,448,948
Common stock, shares issued (in shares)	90,552,687	88,448,948
Related Party
Deferred revenue, current	$ 2,487	$ 2,487
Deferred revenue, noncurrent	$ 1,865	$ 3,730

Balance Sheet Items - Schedule of Property And Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 31,372	$ 27,414
Less: accumulated depreciation and amortization	(11,807)	(9,144)
Property and equipment, net	19,565	18,270
Lab equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	18,276	15,581
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	11,493	2,235
Computer equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	906	895
Furniture and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	697	499
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 0	$ 8,204

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Income Statement [Abstract]
Revenue	$ 2,024	$ 23,662	$ 7,917	$ 30,919
Operating expenses:
Research and development	30,421	28,584	99,689	80,796
General and administrative	9,841	9,711	35,969	28,740
Total operating expenses	40,262	38,295	135,658	109,536
Loss from operations	(38,238)	(14,633)	(127,741)	(78,617)
Other income:
Change in fair value of equity securities	(14)	(4)	(116)	3
Change in fair value of MSKCC success payments liability	(164)	(139)	1,934	395
Other income, net	3,732	4,774	12,308	10,654
Total other income	3,554	4,631	14,126	11,052
Net loss	(34,684)	(10,002)	(113,615)	(67,565)
Other comprehensive income:
Net unrealized gain on available-for-sale marketable securities, net of tax	1,108	155	759	537
Net comprehensive loss	$ (33,576)	$ (9,847)	$ (112,856)	$ (67,028)
Net loss per share, basic (in dollars per share)	$ (0.38)	$ (0.12)	$ (1.26)	$ (0.98)
Net loss per share, diluted (in dollars per share)	$ (0.38)	$ (0.12)	$ (1.26)	$ (0.98)
Weighted-average common shares outstanding, basic (in shares)	90,455,900	83,783,992	90,034,799	68,878,921
Weighted-average common shares outstanding, diluted (in shares)	90,455,900	83,783,992	90,034,799	68,878,921

Revenue - Schedule of Changes in Company's Contract Assets and Liabilities (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Accounts receivable
Accounts receivable, Beginning Balance	$ 148
Accounts receivable, Additions	4,757
Accounts receivable, Deductions	(4,721)
Accounts receivable, Ending Balance	184
Contract assets:
Unbilled accounts receivable, Beginning Balance	1,425
Unbilled accounts receivable, Additions	2,663
Unbilled accounts receivable, Deductions	(3,290)
Unbilled accounts receivable, Ending Balance	798
Contract liabilities:
Deferred revenue, current and long-term, Beginning Balance	8,949
Deferred revenue, current and long-term, Additions	1,250
Deferred revenue, current and long-term, Deductions	(3,423)
Deferred revenue, current and long-term, Ending Balance	$ 6,776

Common Stock (Tables)

9 Months Ended

Sep. 30, 2024

Equity [Abstract]

Schedule of Common Stock Reserved for Future Issuance

Common stock reserved for future issuances consisted of the following:


	As of September 30, 2024	As of December 31, 2023
Stock options, issued and outstanding	11,611,364	9,410,404
Stock options, authorized for future issuances	6,827,620	5,952,012
Stock available under ESPP	2,139,666	1,516,355
Unvested RSUs and PSUs	1,302,846	205,357
Total common stock reserved for future issuances	21,881,496	17,084,128

Stock-Based Compensation - Schedule of Estimated Fair Value of Stock Options on the Grant Date Using Black-Scholes Option-Pricing Model (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Volatility	75.80%
Volatility		74.20%	75.70%	74.20%
Volatility		74.60%	75.90%	75.00%
Expected term (in years)	6 years	6 years
Risk-free interest rate	3.70%	4.10%	3.70%	3.50%
Risk-free interest rate	3.80%	4.60%	4.50%	4.60%
Expected dividend yield	0.00%	0.00%	0.00%	0.00%
Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			5 years	5 years
Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term (in years)			6 years	6 years

Summary of Significant Accounting Policies - Schedule of Concentration of Credit Risk and other Uncertainties (Details) - Customer Concentration Risk	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Revenue \| Major Customers
Concentration Risk [Line Items]
Total	90.80%	90.80%	68.30%	79.10%
Revenue \| Licensee A
Concentration Risk [Line Items]
Total	34.90%		24.20%
Revenue \| Licensee B
Concentration Risk [Line Items]
Total		90.80%		79.10%
Revenue \| Licensee C
Concentration Risk [Line Items]
Total	30.70%		23.60%
Revenue \| Licensee D
Concentration Risk [Line Items]
Total			20.50%
Revenue \| Licensee E
Concentration Risk [Line Items]
Total	14.00%
Revenue \| Licensee F
Concentration Risk [Line Items]
Total	11.20%
Accounts Receivable and Contract Assets \| Major Customers
Concentration Risk [Line Items]
Total			84.40%		47.50%
Accounts Receivable and Contract Assets \| Licensee A
Concentration Risk [Line Items]
Total			68.50%		47.50%
Accounts Receivable and Contract Assets \| Licensee G
Concentration Risk [Line Items]
Total	15.90%

Net Loss Per Share - Computation of the Basic and Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	13,175,175	9,826,108
Stock options
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	11,611,364	9,523,394
Restricted Stock Units RSU and Performance-Based RSUs
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	1,259,377	168,438
Shares committed under ESPP
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities (in shares)	304,434	134,276

Balance Sheet Items - Schedule of Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Prepaid contract manufacturing and clinical costs	$ 3,279	$ 3,942
Prepaid insurance	1,100	993
Other	2,204	1,220
Total	$ 6,583	$ 6,155

Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2024	Nov. 01, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	001-40631
Entity Registrant Name	Caribou Biosciences, Inc.
Entity Incorporation State Country Code	DE
Entity Tax Identification Number	45-3728228
Entity Address Address Line1	2929 7th Street
Entity Address, Address Line Two	Suite 105
Entity Address City Or Town	Berkeley
Entity Address, State and Province	CA
Entity Address Postal Zip Code	94710
City Area Code	510
Local Phone Number	982-6030
Security12b Title	Common Stock, par value $0.0001 per share
Trading Symbol	CRBU
Security Exchange Name	NASDAQ
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		90,552,687
Entity Central Index Key	0001619856
Current Fiscal Year End Date	--12-31
Document Fiscal Period Focus	Q3
Amendment Flag	false
Document Fiscal Year Focus	2024

401(k) Savings Plan	9 Months Ended
401(k) Savings Plan	Sep. 30, 2024
Retirement Benefits [Abstract]
401(K) Savings Plan	401(k) Savings Plan In 2017, we established a defined-contribution savings plan under Section 401(k) of the Internal Revenue Code of 1986, as amended (“Tax Code”). Our 401(k) plan is available to all employees and allows participants to defer a portion of their annual compensation on a pretax basis subject to applicable laws. We also provide a 4% match for employee contributions up to a certain limit. During the nine months ended September 30, 2024, and 2023, we contributed $0.9 million and $0.8 million, respectively, to our 401(k) plan.

Restructuring Charge (Details) $ in Millions		3 Months Ended
Restructuring Charge (Details) $ in Millions	Jul. 16, 2024 position	Sep. 30, 2024 USD ($)
Restructuring and Related Activities [Abstract]
Restructuring, number of positions eliminated \| position	21
Restructuring, number of positions eliminated, period percent	12.00%
Non-recurring restructuring charge \| $		$ 0.6

Leases

9 Months Ended

Sep. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Leases

Operating Lease Obligations

As of September 30, 2024, we had operating leases for our laboratory and office spaces in Berkeley, California, consisting of approximately 75,000 square feet, with remaining lease terms up to 7.8 years. Certain of our laboratory and office space lease agreements include options to extend the terms for a period of five years and also contain provisions for future rent increases. In addition to base rent, we pay our share of operating expenses and taxes.

The components of lease costs, which are included in our unaudited condensed consolidated statements of operations and comprehensive loss, were as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Operating lease cost(1)	$	1,950	$	1,937	$	5,822	$	5,749
Short-term lease cost	63		63		188		188
Total lease cost	$	2,013	$	2,000	$	6,010	$	5,937

Supplemental information related to our leases was as follows (in thousands):


	Nine Months Ended September 30,
	2024		2023
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	2,624	$	2,597

The following table summarizes the weighted-average remaining lease term and weighted-average discount rate for our corporate laboratory and office leases:


	September 30, 2024		December 31, 2023
Weighted-average remaining lease term (years)	6.7		7.4
Weighted-average discount rate	11.3	%	11.3	%

The following table summarizes a maturity analysis of our operating lease liabilities showing the aggregate lease payments as of September 30, 2024 (in thousands):


Remainder of 2024(1)	$	797
2025	4,411
2026	5,720
2027	5,922
2028	6,122
Thereafter	15,993
Total future undiscounted lease payments	38,965
Less imputed interest	(12,324)
Total discounted lease payments	26,641
Less current portion of lease liability	(1,178)
Noncurrent portion of lease liability	$	25,463

(1)Reflects an offset of $0.3 million related to incentives expected to be received in 2024.

Restructuring Charge	9 Months Ended
Restructuring Charge	Sep. 30, 2024
Restructuring and Related Activities [Abstract]
Restructuring Charge	Restructuring ChargeOn July 16, 2024, we announced that we had discontinued preclinical research activities associated with our allogeneic CAR-NK platform and reduced our workforce by 21 positions, or approximately 12%. The workforce reduction was completed during the third quarter of 2024. As a result, we recorded a total of $0.6 million in non-recurring restructuring charges during the three months ended September 30, 2024, consisting primarily of cash severance costs, continuation of benefits, and transition support services for impacted employees.

Leases - Schedule Of Components Lease Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 1,950	$ 1,937	$ 5,822	$ 5,749
Short-term lease cost	63	63	188	188
Total lease cost	2,013	2,000	6,010	5,937
Variable lease cost	$ 700	$ 700	$ 2,000	$ 1,900

Stock-Based Compensation - Schedule of Stock-based Compensation Expense Related to Equity-Based Awards (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 4,069	$ 3,478	$ 12,795	$ 10,194
Stock options
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	3,530	3,188	10,909	9,188
ESPP
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	80	96	309	427
RSUs
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Stock-based compensation	$ 459	$ 194	$ 1,577	$ 579

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (113,615)	$ (67,565)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,743	2,785
Loss (gain) on disposal of fixed assets	4	(34)
Non-cash consideration for licensing and collaboration revenue	(1,634)	(61)
Change in fair value of equity securities	116	(3)
Stock-based compensation expense	12,795	10,194
Change in fair value of MSKCC success payments liability	(1,934)	(395)
Acquired in-process research and development	1,625	0
Accretion of discounts on investments in marketable securities, net	(3,708)	(6,042)
Non-cash lease expense	1,690	1,551
Changes in operating assets and liabilities:
Accounts receivable	(36)	(931)
Contract assets	628	588
Other receivables	603	(130)
Prepaid expenses and other current assets	(428)	852
Other assets	(3,155)	(30)
Accounts payable	(125)	1,089
Accrued expenses and other current liabilities	4,341	2,848
Deferred revenue, current and long-term	(2,173)	(16,337)
Operating lease liabilities	(467)	(291)
Net cash used in operating activities	(102,730)	(71,912)
CASH FLOWS FROM INVESTING ACTIVITIES:
Proceeds from sales and maturities of marketable securities	325,553	283,193
Purchases of marketable securities	(248,889)	(310,566)
Purchases of property and equipment	(4,362)	(9,336)
Payments to acquire in-process research and development	(1,625)	0
Net cash provided by (used in) investing activities	70,677	(36,709)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from public follow-on public offering, net of offering expenses	0	134,536
Proceeds from issuances of common stock pursuant to private placement with Pfizer	0	17,290
Proceeds from exercises of stock options	619	1,508
Proceeds from issuances of common stock under ESPP	913	0
Proceeds from issuances of common stock related to our ATM, net of offering expenses	11,329	1,007
Net cash provided by financing activities	12,861	154,341
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(19,192)	45,720
RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH
Cash and cash equivalents	31,970	104,058
Restricted cash	46	46
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH ON THE BALANCE SHEET	32,016	104,104
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for income taxes	0	170
SUPPLEMENTAL SCHEDULE OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment included in accounts payable and accrued expenses	373	556
Offering costs included in accrued expenses	$ 0	$ 113

Balance Sheet Items - Schedule of Other Receivables (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Balance Sheet Related Disclosures [Abstract]
Patent cost reimbursements	$ 936	$ 1,403
Accrued interest on marketable securities	747	702
Other	0	181
Total	$ 1,683	$ 2,286

Leases - Schedule Of Supplemental Information Related To Leases (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Operating cash flows from operating leases	$ 2,624	$ 2,597
Weighted-average remaining lease term (years)	6 years 8 months 12 days		7 years 4 months 24 days
Weighted-average discount rate	11.30%		11.30%

Revenue - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation Of Revenue [Line Items]
Revenue	$ 2,024	$ 23,662	$ 7,917	$ 30,919
United States
Disaggregation Of Revenue [Line Items]
Revenue	1,657	23,285	7,370	30,416
Rest of world
Disaggregation Of Revenue [Line Items]
Revenue	$ 367	$ 377	$ 547	$ 503

- 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

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Section 50
-Paragraph 1
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Subparagraph (ee)
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Reference 4: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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Reference 5: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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-Section 50
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 1
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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
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-URI https://asc.fasb.org/1943274/2147482810/280-10-50-40

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-4

+ Details

Summary of Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2024 USD ($) segment	Dec. 31, 2023 USD ($)
Accounting Policies [Abstract]
Number of operating segment	1
Number of reportable segment	1
Allowance for doubtful accounts \| $	$ 0	$ 0

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Schedule of Stock Option Activity

The following table summarizes stock option activity under our equity incentive plans during the nine months ended September 30, 2024:


	Stock Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)(1)

Outstanding at December 31, 2023	9,410,404	$	8.03	8.0	$	6,432
Options granted	3,528,702	5.97
Options exercised	(182,217)	3.39
Options cancelled or forfeited	(1,145,525)	8.35
Outstanding at September 30, 2024	11,611,364	$	7.44	7.4	$	41
Exercisable at September 30, 2024	5,810,961	$	8.03	6.1	$	41
Vested and expected to vest at September 30, 2024	11,611,364	$	7.44	7.4	$	41

(1)The aggregate intrinsic value is calculated as the difference between the stock option exercise price and the estimated fair value of the underlying common stock at the end of each reporting period referenced above.

Schedule of Estimated Fair Value of Stock Options on the Grant Date Using Black-Scholes Option-Pricing Model

We estimated the fair value of each employee stock option award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2024	2023	2024	2023
Volatility	75.8%	74.2% to 74.6%	75.7% to 75.9%	74.2% to 75.0%
Expected term (in years)	6.0	6.0	5.0 to 6.0	5.0 to 6.0
Risk-free interest rate	3.7% to 3.8%	4.1% to 4.6%	3.7% to 4.5%	3.5% to 4.6%
Expected dividend yield	0.0%	0.0%	0.0%	0.0%

Schedule of Restricted Stock Units Activity (RSUs)

A summary of the status of and change in unvested RSUs and PSUs as of September 30, 2024, was as follows:


	Number of Shares Underlying Outstanding RSUs and PSUs	Weighted-Average Grant Date Fair Value per RSU and PSU
Unvested, January 1, 2024	205,357	$	8.49
Granted	1,342,842	5.71
Vested	(66,173)	10.07
Forfeited	(179,180)	7.17
Unvested, September 30, 2024	1,302,846	$	5.73

Schedule of Stock-Based Compensation Expenses Recorded in the Condensed Consolidated Statements of Operations and Comprehensive Loss

We recorded stock-based compensation expense related to employee equity-based awards grants in our unaudited condensed consolidated statements of operations and comprehensive loss as follows (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,638	$	1,464	$	5,248	$	4,324
General and administrative	2,431		2,014		7,547		5,870
Total	$	4,069	$	3,478	$	12,795	$	10,194

Schedule of Stock-Based Compensation Expense Related to Equity-Based Awards

The above stock-based compensation expense related to the following equity-based awards (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Stock options	$	3,530	$	3,188	$	10,909	$	9,188
ESPP	80		96		309		427
RSUs	459		194		1,577		579
Total	$	4,069	$	3,478	$	12,795	$	10,194

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
CURRENT ASSETS
Cash and cash equivalents	$ 31,970	$ 51,162
Marketable securities, short-term	196,208	277,665
Accounts receivable	184	148
Contract assets	798	1,425
Other receivables	1,683	2,286
Prepaid expenses and other current assets	6,583	6,155
Total current assets	237,426	338,841
NON-CURRENT ASSETS
Investments in equity securities	9,272	7,753
Marketable securities, long-term	52,837	43,577
Property and equipment, net	19,565	18,270
Operating lease, right of use assets	20,493	22,182
Other assets	4,741	1,586
TOTAL ASSETS	344,334	432,209
CURRENT LIABILITIES
Accounts payable	2,704	3,120
Accrued expenses and other current liabilities	25,448	21,135
Operating lease liabilities, current	1,178	1,200
Deferred revenue ($2,487 from related party as of September 30, 2024, and December 31, 2023)	2,829	2,847
Total current liabilities	32,159	28,302
LONG-TERM LIABILITIES
Deferred revenue, net of current portion ($1,865 and $3,730 from related party as of September 30, 2024, and December 31, 2023, respectively)	3,947	6,102
MSKCC success payments liability	1,005	2,939
Operating lease liabilities, non-current	25,463	25,908
Deferred tax liabilities	557	557
Total liabilities	63,131	63,808
COMMITMENTS AND CONTINGENCIES (Note 9)
STOCKHOLDERS’ EQUITY
Common stock, par value $0.0001 per share, 300,000,000 shares authorized at September 30, 2024, and December 31, 2023; 90,552,687 and 88,448,948 shares issued and outstanding as of September 30, 2024, and December 31, 2023, respectively	9	8
Additional paid-in-capital	693,305	667,648
Accumulated other comprehensive income	789	30
Accumulated deficit	(412,900)	(299,285)
Total stockholders’ equity	281,203	368,401
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY	$ 344,334	$ 432,209

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Assumptions Used in Valuation of MSKCC Success Payments Liability (Details)	12 Months Ended
	Dec. 31, 2023 $ / shares	Sep. 30, 2024
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Common stock value per share (in dollars per share)	$ 5.1914
Fair value of common stock
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	5.73	1.96
Risk-free interest rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	0.0388
Expected volatility
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	0.79
Probability of achieving multiple of Initial Share Price \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	0.052
Probability of achieving multiple of Initial Share Price \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability, measurement input	0.181
Expected term (years) \| Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability assumptions term	3 years 8 months 12 days
Expected term (years) \| Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Success payment liability assumptions term	5 years 2 months 12 days

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Financial Instruments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Assets:
Cash and cash equivalents	$ 31,970	$ 51,162	$ 104,058
U.S. Treasury bills
Assets:
Cash and cash equivalents	5,596	23,527
Commercial paper
Assets:
Cash and cash equivalents	5,990	9,759
Fair Value, Recurring
Assets:
Assets fair value	281,015	372,404
Liabilities:
Liabilities fair value	1,005	2,939
Fair Value, Recurring \| MSKCC success payments liability
Liabilities:
Liabilities fair value	1,005	2,939
Fair Value, Recurring \| U.S. Treasury bills
Assets:
Assets fair value	193,812	262,439
Fair Value, Recurring \| U.S. government agency bonds
Assets:
Assets fair value	31,515	40,185
Fair Value, Recurring \| Commercial paper
Assets:
Assets fair value	30,203	40,373
Fair Value, Recurring \| Money market funds
Assets:
Assets fair value	16,411	17,876
Fair Value, Recurring \| Corporate debt securities
Assets:
Assets fair value	9,074	11,531
Fair Value, Recurring \| Level 1
Assets:
Assets fair value	210,223	280,315
Liabilities:
Liabilities fair value	0	0
Fair Value, Recurring \| Level 1 \| MSKCC success payments liability
Liabilities:
Liabilities fair value	0	0
Fair Value, Recurring \| Level 1 \| U.S. Treasury bills
Assets:
Assets fair value	193,812	262,439
Fair Value, Recurring \| Level 1 \| U.S. government agency bonds
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 1 \| Commercial paper
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 1 \| Money market funds
Assets:
Assets fair value	16,411	17,876
Fair Value, Recurring \| Level 1 \| Corporate debt securities
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 2
Assets:
Assets fair value	70,792	92,089
Liabilities:
Liabilities fair value	0	0
Fair Value, Recurring \| Level 2 \| MSKCC success payments liability
Liabilities:
Liabilities fair value	0	0
Fair Value, Recurring \| Level 2 \| U.S. Treasury bills
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 2 \| U.S. government agency bonds
Assets:
Assets fair value	31,515	40,185
Fair Value, Recurring \| Level 2 \| Commercial paper
Assets:
Assets fair value	30,203	40,373
Fair Value, Recurring \| Level 2 \| Money market funds
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 2 \| Corporate debt securities
Assets:
Assets fair value	9,074	11,531
Fair Value, Recurring \| Level 3
Assets:
Assets fair value	0	0
Liabilities:
Liabilities fair value	1,005	2,939
Fair Value, Recurring \| Level 3 \| MSKCC success payments liability
Liabilities:
Liabilities fair value	1,005	2,939
Fair Value, Recurring \| Level 3 \| U.S. Treasury bills
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 3 \| U.S. government agency bonds
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 3 \| Commercial paper
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 3 \| Money market funds
Assets:
Assets fair value	0	0
Fair Value, Recurring \| Level 3 \| Corporate debt securities
Assets:
Assets fair value	$ 0	$ 0

401(k) Savings Plan (Details) - 2017 Plan - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Defined contribution plan, Employer matching contribution percent of match	4.00%
Employer contribution	$ 0.9	$ 0.8

Revenue - Additional Information (Details) - USD ($)	3 Months Ended		9 Months Ended
Revenue - Additional Information (Details) - USD ($)	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Disaggregation Of Revenue [Line Items]
Revenue recognized included in the opening contract liabilities balance			$ 2,200,000	$ 23,200,000
Collaboration and License Agreement with AbbVie
Disaggregation Of Revenue [Line Items]
Revenues	$ 0	$ 21,500,000	0	24,500,000
Point in Time
Disaggregation Of Revenue [Line Items]
Revenue recognized, performance obligation, amount	1,400,000	1,600,000	6,000,000.0	5,800,000
Over Time
Disaggregation Of Revenue [Line Items]
Revenue recognized, performance obligation, amount	$ 600,000	$ 22,100,000	$ 1,900,000	$ 25,100,000

- 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

- Definition

+ References

+ Details

Revenue

9 Months Ended

Sep. 30, 2024

Revenue from Contract with Customer [Abstract]

Revenue

Disaggregation of Revenue

We disaggregate revenue by geographical market based on the location of research and development activities of our licensees and collaborators. The following table is a summary of revenue by geographic location for the three and nine months ended September 30, 2024, and 2023 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
United States	$	1,657	$	23,285	$	7,370	$	30,416
Rest of world	367		377		547		503
Total	$	2,024	$	23,662	$	7,917	$	30,919

During the three months ended September 30, 2024, we recognized $1.4 million of revenue related to performance obligations satisfied at a point in time, and we recognized $0.6 million of revenue related to performance obligations satisfied over time.

During the three months ended September 30, 2023, we recognized $1.6 million of revenue related to performance obligations satisfied at a point in time, and we recognized $22.1 million of revenue related to performance obligations satisfied over time that included $21.5 million in licensing and collaboration revenue associated with the now-terminated AbbVie Agreement.

During the nine months ended September 30, 2024, we recognized $6.0 million of revenue related to performance obligations satisfied at a point in time, and we recognized $1.9 million of revenue related to performance obligations satisfied over time.

During the nine months ended September 30, 2023, we recognized $5.8 million of revenue related to performance obligations satisfied at a point in time, and we recognized $25.1 million of revenue related to performance obligations satisfied over time which included $24.5 million in licensing and collaboration revenue associated with the now-terminated AbbVie Agreement.

Contract Balances

Accounts receivable relate to our right to consideration for performance obligations completed (or partially completed) for which we have an unconditional right to consideration. Our accounts receivable balances represent amounts that we billed to our licensees with invoices outstanding as of the end of a reporting period.

Contract assets are rights to consideration in exchange for a license that we have granted to a licensee when the right is conditional on something other than the passage of time. Our contract asset balances represent royalties and milestone payments from our other license agreements that are unbilled as of the end of a reporting period.

Contract liabilities consist of deferred revenue and relate to amounts invoiced to, or advance consideration received from, licensees that precede our satisfaction of the associated performance obligations. As of September 30, 2024, and December 31, 2023, our deferred revenue balance primarily resulted from the upfront payment received relating to our performance obligation to Pfizer Inc. (“Pfizer”). The remaining deferred revenue relates to upfront payments received under license agreements that also include nonrefundable annual license fees, which are accounted for as material rights for license renewals and are recognized at the point in time when annual license fees are paid by the licensees and the renewal periods begin.

The following table presents changes in our contract assets and liabilities during the nine months ended September 30, 2024 (in thousands):


	Balance as of December 31, 2023		Additions		Deductions		Balance as of September 30, 2024
Accounts receivable	$	148	$	4,757	$	(4,721)	$	184

Contract assets:
Unbilled accounts receivable	$	1,425	$	2,663	$	(3,290)	$	798

Contract liabilities:
Deferred revenue, current and long-term	$	8,949	$	1,250	$	(3,423)	$	6,776

During the nine months ended September 30, 2024, and 2023, we recognized $2.2 million and $23.2 million of revenue, respectively, which was included in the opening contract liabilities balances at the beginning of the respective periods.

Transaction Prices Allocated to Remaining Performance Obligations

Remaining performance obligations represent in aggregate the amount of a transaction price that has been allocated to performance obligations not delivered as of the end of a reporting period. The value of transaction prices allocated to remaining unsatisfied performance obligations as of September 30, 2024, was approximately $6.8 million. We expect to recognize approximately $2.8 million of remaining performance obligations as revenue in the next 12 months and to recognize the remainder thereafter.

Capitalized Contract Acquisition Costs and Fulfillment Costs

We did not incur any expenses to obtain our existing contracts, and costs to fulfill those contracts do not generate or enhance our resources. As such, no costs to obtain or fulfill a contract have been capitalized in any period.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479806/606-10-50-9

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
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-Paragraph 10
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-URI https://asc.fasb.org/1943274/2147479806/606-10-50-10

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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-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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-URI https://asc.fasb.org/1943274/2147479806/606-10-50-12

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 12
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Name Accounting Standards Codification
-Topic 606
-Publisher FASB
-URI https://asc.fasb.org/606/tableOfContent

+ Details

Balance Sheet Items - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Balance Sheet Related Disclosures [Abstract]
Depreciation and amortization expense related to property and equipment	$ 1.1	$ 1.6	$ 2.7	$ 2.8

Leases - Schedule of Future Minimum Commitments Under Lease Contracts (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2024	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Remainder of 2024	$ 797
2025	4,411
2026	5,720
2027	5,922
2028	6,122
Thereafter	15,993
Total future undiscounted lease payments	38,965
Less imputed interest	(12,324)
Total discounted lease payments	26,641
Less current portion of lease liability	(1,178)	$ (1,200)
Noncurrent portion of lease liability	25,463	$ 25,908
Expected incentive offset in first year	$ 300

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Basis of Presentation and Principles of Consolidation

Our unaudited condensed consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States (“U.S. GAAP”) and include our accounts and the accounts of our wholly owned subsidiaries. All intercompany accounts and transactions are eliminated in consolidation.

Use of Estimates

The preparation of unaudited condensed consolidated financial statements in conformity with U.S. GAAP requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities; the disclosure of contingent assets and liabilities at the date of our unaudited condensed consolidated financial statements; and the reported amounts of revenue, income, and expenses during the applicable reporting period. On an ongoing basis, we evaluate our estimates and assumptions, including those related to revenue recognition, stock-based compensation expense, accrued expenses related to research and development activities, valuation of the Memorial Sloan Kettering Cancer Center (“MSKCC”) success payments liability, operating lease right-of-use assets and liabilities, and income taxes. Our management bases its estimates on historical experience and various other assumptions that they believe 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 may differ materially from those estimates.

Segments

We operate and manage our business as one reportable operating segment, which is the business of developing a pipeline of allogeneic CAR-T cell therapies. Our president and chief executive officer, who is the chief operating decision maker, reviews financial information on an aggregate basis for allocating resources and evaluating financial performance. All long-lived assets are maintained in the United States.

Concentration of Credit Risk and Other Uncertainties

Concentrations of Credit Risk and Other Uncertainties

Financial instruments that potentially subject us to concentration of credit risk consist of cash and cash equivalents, accounts receivable, contract assets, other receivables, and investments in marketable securities and equity securities. Substantially all our cash and cash equivalents are deposited in accounts at four financial institutions, and our account balances exceed federally insured limits. We mitigate the risks by investing in high-grade instruments, limiting our exposure to one issuer, and we monitor the ongoing creditworthiness of these financial institutions and issuers.

Licensees that represent 10% or more of our revenue and accounts receivable and contract assets were as follows:


	Revenue				Revenue				Accounts Receivable and Contract Assets
	Three Months Ended				Nine Months Ended				As of September 30, 2024		As of December 31, 2023
	September 30, 2024		September 30, 2023		September 30, 2024		September 30, 2023
Licensee A	34.9	%	*		24.2	%	*		68.5	%	47.5	%
Licensee B	*		90.8	%	*		79.1	%	*		*
Licensee C	30.7	%	*		23.6	%	*		*		*
Licensee D	*		*		20.5	%	*		*		*
Licensee E	14.0	%	*		*		*		*		*
Licensee F	11.2	%	*		*		*		*		*
Licensee G	*		*		*		*		15.9	%	*
Total	90.8	%	90.8	%	68.3	%	79.1	%	84.4	%	47.5	%

*Less than 10%

We monitor economic conditions to identify facts or circumstances that may indicate if any of our accounts receivable are not collectible or if contract assets should be impaired.

Recent Accounting Pronouncements Not Yet Adopted

In October 2023, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2023-06, Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative. This ASU aligns the requirements in the Accounting Standards Codification (“ASC”) to the removal of certain disclosure requirements set out in Regulation S-X and Regulation S-K, announced by the U.S. Securities and Exchange Commission (“SEC”). The effective date for each amended topic in the ASC is either the date on which the SEC’s removal of the related disclosure requirement from Regulation S-X or Regulation S-K becomes effective or June 30, 2027, if the SEC has not removed the requirements by that date. Early adoption is prohibited. We are currently evaluating the impact of the new guidance and do not expect that the adoption of ASU 2023-06 will have a material impact on our consolidated financial statements.

In November 2023, the FASB issued ASU 2023-07, Segment Reporting (Topic 280): Improvements to Reportable Segment Disclosures. This ASU requires public entities to disclose information about their reportable segments’ significant expenses and other segment items on an interim and annual basis. Public entities with a single reportable segment are required to apply the disclosure requirements in ASU 2023-07, as well as all existing segment disclosures and reconciliation requirements in ASC 280 on an interim and annual basis. ASU 2023-07 is effective for fiscal years beginning after December 15, 2023, and for interim periods within fiscal years beginning after December 15, 2024, with early adoption permitted. We are currently evaluating the impact of the adoption of ASU 2023-07.

In December 2023, the FASB issued ASU 2023-09, Income Taxes (Topic 740): Improvements to Income Tax Disclosures. This ASU requires public entities, on an annual basis, to provide disclosure of specific categories in the rate

reconciliation, as well as disclosure of income taxes paid disaggregated by jurisdiction. ASU 2023-09 is effective for fiscal years beginning after December 15, 2024, with early adoption permitted. We are currently evaluating the impact of the new guidance and do not expect that the adoption of ASU 2023-09 will have a material impact on our consolidated financial statements.

In March 2024, the FASB issued ASU No. 2024-02, Codification Improvements - Amendments to Remove References to the Concepts Statements. The amendments in ASU 2024-02 clarify and simplify references to certain concept statements within U.S. GAAP. ASU 2024-02 is effective for fiscal years beginning after December 15, 2024, with early application permitted. We are currently evaluating the impact of the adoption of ASU 2024-02.

- Definition

Disclosure of accounting policy for segment reporting.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 41
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Reference 2: http://www.xbrl.org/2003/role/exampleRef
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Reference 5: 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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+ Details

Fair Value Measurements and Fair Value of Financial Instruments - Schedule of Fair Value and Amortized Cost of Cash Equivalents and Available-for-Sale Marketable Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Debt Securities, Available-for-Sale [Line Items]
Cash, cash equivalents, and available-for-sale, amortized cost	$ 280,226	$ 372,374
Cash and cash equivalents, Amortized Cost Basis	31,970	51,162	$ 104,058
Unrealized Gains	795	382
Unrealized Losses	(6)	(352)
Available-for-sale marketable securities and cash and cash equivalents, Estimated Fair Value	281,015	372,404
Marketable securities, short-term	196,208	277,665
Marketable securities, long-term	52,837	43,577
U.S. Treasury bills
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents, Amortized Cost Basis	5,596	23,527
Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents, Amortized Cost Basis	5,990	9,759
U.S. government agency bonds
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents, Amortized Cost Basis	3,973
Money market funds
Debt Securities, Available-for-Sale [Line Items]
Cash and cash equivalents, Amortized Cost Basis	16,411	17,876
Cash and cash equivalents, Estimated Fair Value	16,411	17,876
U.S. Treasury bills
Debt Securities, Available-for-Sale [Line Items]
Cash, cash equivalents, and available-for-sale, amortized cost	193,198	262,328
Unrealized Gains	617	331
Unrealized Losses	(3)	(220)
Available-for-sale marketable securities and cash and cash equivalents, Estimated Fair Value	193,812	262,439
Commercial paper
Debt Securities, Available-for-Sale [Line Items]
Cash, cash equivalents, and available-for-sale, amortized cost		40,386
Available-for-sale marketable securities, Amortized Cost Basis	30,173
Unrealized Gains	32	0
Unrealized Losses	(2)	(13)
Available-for-sale marketable securities and cash and cash equivalents, Estimated Fair Value		40,373
Available-for-sale marketable securities, Estimated Fair Value	30,203
U.S. government agency bonds
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale marketable securities, Amortized Cost Basis	31,380	40,295
Unrealized Gains	136	1
Unrealized Losses	(1)	(111)
Available-for-sale marketable securities, Estimated Fair Value	31,515	40,185
Corporate debt securities
Debt Securities, Available-for-Sale [Line Items]
Available-for-sale marketable securities, Amortized Cost Basis	9,064	11,489
Unrealized Gains	10	50
Unrealized Losses	0	(8)
Available-for-sale marketable securities, Estimated Fair Value	$ 9,074	$ 11,531

Fair Value Measurements and Fair Value of Financial Instruments - Contractual Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Fair Value Disclosures [Abstract]
Due in less than one year	$ 196,208	$ 277,665
Due in one to five years	52,837	$ 43,577
Total	$ 249,045

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023	Sep. 30, 2023
Statement of Cash Flows [Abstract]
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — BEGINNING OF PERIOD	$ 51,208	$ 104,104	$ 58,384
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH — END OF PERIOD	$ 32,016	$ 51,208	$ 104,104

Stock-Based Compensation - Schedule of Stock Option Activity (Details) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares
Stock Options
Outstanding, Beginning Balance (in shares) \| shares	9,410,404
Granted (in shares) \| shares	3,528,702
Exercised (in shares) \| shares	(182,217)
Cancelled or forfeited (in shares) \| shares	(1,145,525)
Outstanding, Ending Balance (in shares) \| shares	11,611,364	9,410,404
Exercisable (in shares) \| shares	5,810,961
Vested and expected to vest (in shares) \| shares	11,611,364
Weighted- Average Exercise Price
Outstanding, Beginning Balance (in dollars per share) \| $ / shares	$ 8.03
Granted (in dollars per share) \| $ / shares	5.97
Exercised (in dollars per share) \| $ / shares	3.39
Cancelled or forfeited (in dollars per share) \| $ / shares	8.35
Outstanding, Ending Balance (in dollars per share) \| $ / shares	7.44	$ 8.03
Exercisable (in dollars per share) \| $ / shares	8.03
Vested and expected to vest (in dollars per share) \| $ / shares	$ 7.44
Weighted- Average Remaining Contractual Term (years)
Outstanding (in years)	7 years 4 months 24 days	8 years
Exercisable (in years)	6 years 1 month 6 days
Vested and expected to vest (in years)	7 years 4 months 24 days
Aggregate Intrinsic Value (in thousands)
Outstanding \| $	$ 41	$ 6,432
Exercisable \| $	41
Vested and expected to vest \| $	$ 41

Net Loss Per Share - Basic and Diluted Net Income Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2024	Sep. 30, 2023
Numerator:
Net loss	$ (34,684)	$ (37,697)	$ (41,234)	$ (10,002)	$ (29,519)	$ (28,044)	$ (113,615)	$ (67,565)
Denominator:
Weighted-average common shares outstanding used to compute net loss per share, basic (in shares)	90,455,900			83,783,992			90,034,799	68,878,921
Weighted-average common shares outstanding used to compute net loss per share, diluted (in shares)	90,455,900			83,783,992			90,034,799	68,878,921
Net loss per share, basic (in dollars per share)	$ (0.38)			$ (0.12)			$ (1.26)	$ (0.98)
Net loss per share, diluted (in dollars per share)	$ (0.38)			$ (0.12)			$ (1.26)	$ (0.98)

- Definition

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

+ References

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

+ Details

- Definition

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

+ References

+ Details

Insider Trading Arrangements	3 Months Ended	9 Months Ended
Insider Trading Arrangements	Sep. 30, 2024 shares	Sep. 30, 2024 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Tina Albertson [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On August 13, 2024, Tina Albertson, M.D., Ph.D., our chief medical officer, entered into a Rule 10b5-1 trading arrangement (as that term is defined in Regulation S-K, Item 408) that is intended to qualify as an “eligible sell-to-cover transaction” (as described in Rule 10b5-1(c)(1)(ii)(D)(3) under the Exchange Act) and is intended to satisfy the affirmative defense in Rule 10b5-1(c) under the Exchange Act. This sell-to-cover arrangement applies to restricted stock units or performance-based stock units (collectively, “RSUs”), whether vesting is based on the passage of time and/or the achievement of performance goals, that were previously granted or that could in the future be granted by us from time to time. This arrangement provides for the automatic sale of shares of common stock that would otherwise be issuable on each settlement date of a covered RSU in an amount necessary to satisfy the applicable tax withholding obligations, with the proceeds of the sale delivered to us in satisfaction of the applicable tax withholding obligations. The number of shares of common stock that will be sold under these arrangements is not currently determinable as the number will vary based on the extent to which vesting conditions are satisfied, the market price of our common stock at the time of settlement, and the potential future grant of RSUs subject to this arrangement. The sell-to-cover instructions will remain in place indefinitely unless revoked in writing (including as to any particular sell-to-cover sale) in accordance with their terms.
Name	Tina Albertson
Title	chief medical officer
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 13, 2024
Rachel Haurwitz [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement		On September 6, 2024, City Canyon Family Trust, a trust for which Rachel Haurwitz, Ph.D., our president and chief executive officer and a member of our Board of Directors, is a co-trustee along with her husband, adopted a Rule 10b5-1 trading arrangement, providing for the sale from time to time of up to 540,000 shares of common stock in amounts and at prices determined in accordance with plan terms. The trading arrangement is intended to satisfy the affirmative defense in Rule 10b5-1(c) under the Exchange Act. The duration of the trading arrangement is until December 12, 2025, or earlier if all transactions under the trading arrangement are completed.
Name	Rachel Haurwitz
Title	president and chief executive officer and a member of our Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	September 6, 2024
Expiration Date	December 12, 2025
Arrangement Duration	462 days
Aggregate Available	540,000	540,000

Stock-Based Compensation

9 Months Ended

Sep. 30, 2024

Share-Based Payment Arrangement [Abstract]

Stock-Based Compensation

Equity Incentive Plans

In July 2021, our board of directors adopted, and our stockholders approved, the 2021 Equity Incentive Plan (“2021 Plan”) that became effective on July 22, 2021. As of September 30, 2024, we had 6,827,620 shares available for issuance under the 2021 Plan.

The following table summarizes stock option activity under our equity incentive plans during the nine months ended September 30, 2024:


	Stock Options	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (years)	Aggregate Intrinsic Value (in thousands)(1)

Outstanding at December 31, 2023	9,410,404	$	8.03	8.0	$	6,432
Options granted	3,528,702	5.97
Options exercised	(182,217)	3.39
Options cancelled or forfeited	(1,145,525)	8.35
Outstanding at September 30, 2024	11,611,364	$	7.44	7.4	$	41
Exercisable at September 30, 2024	5,810,961	$	8.03	6.1	$	41
Vested and expected to vest at September 30, 2024	11,611,364	$	7.44	7.4	$	41

Grant Date Fair Value

During the three months ended September 30, 2024, and 2023, we granted 391,525 and 384,095 stock options to employees with a weighted average grant date fair value of $1.49 and $3.64, respectively. During the nine months ended September 30, 2024, and 2023, we granted 3,528,702 and 3,406,801 stock options to employees with a weighted average grant date fair value of $4.09 and $3.91, respectively.

We estimated the fair value of each employee stock option award on the grant date using the Black-Scholes option-pricing model based on the following assumptions:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2024	2023	2024	2023
Volatility	75.8%	74.2% to 74.6%	75.7% to 75.9%	74.2% to 75.0%
Expected term (in years)	6.0	6.0	5.0 to 6.0	5.0 to 6.0
Risk-free interest rate	3.7% to 3.8%	4.1% to 4.6%	3.7% to 4.5%	3.5% to 4.6%
Expected dividend yield	0.0%	0.0%	0.0%	0.0%

As of September 30, 2024, there was $24.5 million of unrecognized stock-based compensation expense related to employee stock options that is expected to be recognized over a weighted-average period of 2.6 years.

Restricted Stock Units

During the nine months ended September 30, 2024, we granted 1,342,842 restricted stock units (“RSUs”) to employees, and we did not grant any performance-based RSUs (“PSUs”) to employees under the 2021 Plan. A summary of the status of and change in unvested RSUs and PSUs as of September 30, 2024, was as follows:


	Number of Shares Underlying Outstanding RSUs and PSUs	Weighted-Average Grant Date Fair Value per RSU and PSU
Unvested, January 1, 2024	205,357	$	8.49
Granted	1,342,842	5.71
Vested	(66,173)	10.07
Forfeited	(179,180)	7.17
Unvested, September 30, 2024	1,302,846	$	5.73

On August 22, 2022, we granted PSUs to our executive officers, which will vest contingent upon the achievement of a clinical milestone for CB-010 during a performance period ending December 31, 2024, and the executive officer’s continued employment during the performance period. As of September 30, 2024, the achievement of this milestone was not considered probable and, therefore, no stock-based compensation was recorded.

As of September 30, 2024, the total unrecognized stock-based compensation expense related to unvested RSUs was $5.7 million, which is expected to be recognized over the remaining weighted-average vesting period of 2.9 years. As of September 30, 2024, there was approximately $0.4 million of unrecognized stock-based compensation expense related to unvested PSUs.

Employee Stock Purchase Plan (“ESPP”)

In July 2021, our board of directors adopted, and our stockholders approved, the ESPP, which became effective on July 22, 2021. We issued 468,745 shares of common stock under the ESPP as of September 30, 2024. We recorded $0.1 million in accrued liabilities related to contributions withheld as of September 30, 2024.

Stock-Based Compensation Expense


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Research and development	$	1,638	$	1,464	$	5,248	$	4,324
General and administrative	2,431		2,014		7,547		5,870
Total	$	4,069	$	3,478	$	12,795	$	10,194

The above stock-based compensation expense related to the following equity-based awards (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
Stock options	$	3,530	$	3,188	$	10,909	$	9,188
ESPP	80		96		309		427
RSUs	459		194		1,577		579
Total	$	4,069	$	3,478	$	12,795	$	10,194

Revenue (Tables)

9 Months Ended

Sep. 30, 2024

Revenue from Contract with Customer [Abstract]

Schedule of Disaggregation of Revenue

The following table is a summary of revenue by geographic location for the three and nine months ended September 30, 2024, and 2023 (in thousands):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2024		2023		2024		2023
United States	$	1,657	$	23,285	$	7,370	$	30,416
Rest of world	367		377		547		503
Total	$	2,024	$	23,662	$	7,917	$	30,919

Schedule of Changes in Company's Contract Assets and Liabilities

The following table presents changes in our contract assets and liabilities during the nine months ended September 30, 2024 (in thousands):


	Balance as of December 31, 2023		Additions		Deductions		Balance as of September 30, 2024
Accounts receivable	$	148	$	4,757	$	(4,721)	$	184

Contract assets:
Unbilled accounts receivable	$	1,425	$	2,663	$	(3,290)	$	798

Contract liabilities:
Deferred revenue, current and long-term	$	8,949	$	1,250	$	(3,423)	$	6,776

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Revenue	$ 2,024	$ 23,662	$ 7,917	$ 30,919
Related Party
Revenue	$ 622	$ 622	$ 3,488	$ 1,772

- Definition

+ References

+ Details

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

There have been no changes to the significant accounting policies disclosed in Note 2 to the annual consolidated financial statements for the year ended December 31, 2023, included in our Annual Report on Form 10-K (“Form 10-K”).

Basis of Presentation and Principles of Consolidation

Use of Estimates

Segments

Concentrations of Credit Risk and Other Uncertainties

Licensees that represent 10% or more of our revenue and accounts receivable and contract assets were as follows:


	Revenue				Revenue				Accounts Receivable and Contract Assets
	Three Months Ended				Nine Months Ended				As of September 30, 2024		As of December 31, 2023
	September 30, 2024		September 30, 2023		September 30, 2024		September 30, 2023
Licensee A	34.9	%	*		24.2	%	*		68.5	%	47.5	%
Licensee B	*		90.8	%	*		79.1	%	*		*
Licensee C	30.7	%	*		23.6	%	*		*		*
Licensee D	*		*		20.5	%	*		*		*
Licensee E	14.0	%	*		*		*		*		*
Licensee F	11.2	%	*		*		*		*		*
Licensee G	*		*		*		*		15.9	%	*
Total	90.8	%	90.8	%	68.3	%	79.1	%	84.4	%	47.5	%

*Less than 10%

We monitor economic conditions to identify facts or circumstances that may indicate if any of our accounts receivable are not collectible or if contract assets should be impaired. No allowance for credit losses or contract asset impairment was recorded as of September 30, 2024, or December 31, 2023.

Recent Accounting Pronouncements Not Yet Adopted

Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Research, Manufacturing, and License Agreements We enter into various agreements in the ordinary course of business, such as those with contract manufacturing organizations (“CMOs”), suppliers, clinical research organizations (“CROs”), clinical trial sites, licensors, assignors, and the like. These agreements provide for termination by either party in certain circumstances, generally with less than one-year notice and are, therefore, cancellable contracts and, if cancelled, are not anticipated to have a material effect on our unaudited condensed consolidated financial condition, results of operations, or cash flows. Some of these agreements also include contingent payments that will become payable if and when certain development, regulatory, clinical, and/or commercial milestones are achieved by us. As of September 30, 2024, satisfaction and timing of such contingent payments are uncertain and thus cannot be reasonably estimated. Guarantees and Indemnifications In the ordinary course of business, we enter into agreements that contain a variety of representations and warranties and provide for certain indemnifications by us. Our exposure under these agreements is unknown because claims may be made against us in the future. As of September 30, 2024, and December 31, 2023, we did not have any material indemnification claims that were probable or reasonably possible, and consequently, we have not recorded related liabilities. Litigation From time to time, we may become involved in litigation arising in the ordinary course of business. We record a liability for such litigation when it is probable that future losses will be incurred and if such losses can be reasonably estimated. Significant judgment by us is required to determine both probability and the estimated amount. On April 11, 2023, a putative class action lawsuit was filed in the U.S. District Court for the Northern District of California against our company and certain of our officers and current and former members of our board of directors, Bergman v. Caribou Biosciences, Inc., et al., Case Number 23-cv-01742 (“Bergman Case”). The Bergman complaint challenged disclosures regarding our company’s business, operations, and prospects, specifically with respect to the alleged durability of CB-010’s therapeutic effect and the product candidate’s clinical and commercial prospects, in alleged violation of Sections 11 and 15 of the Securities Act of 1933, as amended (“Securities Act”), and Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended (“Exchange Act”). On September 18, 2023, plaintiffs filed an amended complaint adding the initial public offering (“IPO”) underwriters as defendants and making substantially the same allegations as the original complaint. On November 14, 2023, we filed a motion to dismiss the amended complaint for failure to state a claim. Motion to dismiss briefing was completed on February 21, 2024. On April 22, 2024, we reached an agreement in principle with plaintiffs to settle the Bergman Case for $3.9 million, which was included in general and administrative expense for the three months ended March 31, 2024, in exchange for a full release of the putative class’s claims against us and all our current and former officers, current and former members of our board of directors, the IPO underwriters, and the other named defendant. The parties filed a settlement agreement with the court on June 26, 2024, and, on October 15, 2024, the court issued an order preliminarily approving the settlement and setting a final settlement approval hearing for February 18, 2025.

Fair Value Measurements and Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements and Fair Value of Financial Instruments

The authoritative guidance on fair value measurements establishes a three-tier fair value hierarchy for disclosure of fair value measurements as follows:

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

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

Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities.

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

Our financial instruments consist of Level 1, Level 2, and Level 3 financial instruments. We generally classify our marketable securities as Level 1 or Level 2. Instruments are classified as Level 2 when observable market prices for identical securities that are traded in less active markets are used. When observable market prices for identical securities are not available, such instruments are priced using benchmark curves, benchmarking of like securities, sector groupings, matrix pricing, and valuation models. These valuation models are proprietary to the pricing providers or brokers and incorporate a number of inputs including, in approximate order of priority: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. For certain security types, additional inputs may be used, or some of the standard inputs may not be applicable. Evaluators may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs listed are available for use in the evaluation process for each security valuation on any given day. Changes in the ability to observe valuation inputs may result in a reclassification of levels of certain securities within the fair value hierarchy. We recognize transfers into and out of levels within the fair value hierarchy in the period in which the actual event or change in circumstances that caused the transfer occurs. No such transfers occurred during the nine months ended September 30, 2024, and 2023. Level 1 financial instruments are comprised of money market fund investments and U.S. Treasury bills. Level 2 financial instruments are comprised of commercial paper, corporate debt securities, and U.S. government agency bonds. Financial assets and liabilities are considered Level 3 when their fair values are determined using pricing models, discounted cash flow methodologies, or similar techniques, and at least one significant model assumption or input is unobservable. Level 3 financial instruments consist of the MSKCC success payments liability.

The following table sets forth our financial instruments that were measured at fair value on a recurring basis by level within the fair value hierarchy (in thousands):


	Fair Value Measurements as of September 30, 2024
	Total		Level 1		Level 2		Level 3
Assets:
U.S. Treasury bills ($5,596 included in cash and cash equivalents)	$	193,812	$	193,812	$	—	$	—
U.S. government agency bonds ($3,973 included in cash and cash equivalents)	31,515		—		31,515		—
Commercial paper ($5,990 included in cash and cash equivalents)	30,203		—		30,203		—
Money market fund investments (included in cash and cash equivalents)	16,411		16,411		—		—
Corporate debt securities	9,074		—		9,074		—
Total fair value of assets	$	281,015	$	210,223	$	70,792	$	—
Liabilities:
MSKCC success payments liability	$	1,005	$	—	$	—	$	1,005
Total fair value of liabilities	$	1,005	$	—	$	—	$	1,005


	Fair Value Measurements as of December 31, 2023
	Total		Level 1		Level 2		Level 3
Assets:
U.S. Treasury bills ($23,527 included in cash and cash equivalents)	$	262,439	$	262,439	$	—	$	—
Commercial paper ($9,759 included in cash and cash equivalents)	40,373		—		40,373		—
U.S. government agency bonds	40,185		—		40,185		—
Money market fund investments (included in cash and cash equivalents)	17,876		17,876		—		—
Corporate debt securities	11,531		—		11,531		—
Total fair value of assets	$	372,404	$	280,315	$	92,089	$	—
Liabilities:
MSKCC success payments liability	$	2,939	$	—	$	—	$	2,939
Total fair value of liabilities	$	2,939	$	—	$	—	$	2,939


	As of September 30, 2024
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury bills ($5,596 included in cash and cash equivalents)	$	193,198	$	617	$	(3)	$	193,812
U.S. government agency bonds ($3,973 included in cash and cash equivalents)	31,380		136		(1)		31,515
Commercial paper ($5,990 included in cash and cash equivalents)	30,173		32		(2)		30,203
Money market fund investments (included in cash equivalents)	16,411		—		—		16,411
Corporate debt securities	9,064		10		—		9,074
Total cash equivalents and marketable securities	$	280,226	$	795	$	(6)	$	281,015

Classified as:
Cash and cash equivalents							$	31,970
Marketable securities, short-term							196,208
Marketable securities, long-term							52,837
Total cash equivalents and marketable securities							$	281,015


	As of December 31, 2023
	Amortized Cost Basis		Unrealized Gains		Unrealized Losses		Estimated Fair Value
U.S. Treasury bills ($23,527 included in cash and cash equivalents)	$	262,328	$	331	$	(220)	$	262,439
Commercial paper ($9,759 included in cash and cash equivalents)	40,386		—		(13)		40,373
U.S. government agency bonds	40,295		1		(111)		40,185
Money market fund investments (included in cash equivalents)	17,876		—		—		17,876
Corporate debt securities	11,489		50		(8)		11,531
Total cash equivalents and marketable securities	$	372,374	$	382	$	(352)	$	372,404

Classified as:
Cash and cash equivalents							$	51,162
Marketable securities, short-term							277,665
Marketable securities, long-term							43,577
Total cash equivalents and marketable securities							$	372,404

The following table presents the fair value of available-for-sale marketable securities by contractual maturities (in thousands):


	September 30, 2024
Due in less than one year	$	196,208
Due in one to five years	52,837
Total	$	249,045

The following table sets forth a summary of the changes in the fair value of our Level 3 financial liability (in thousands):


	MSKCC Success Payments Liability
Balance at December 31, 2023	$	2,939
Change in fair value	(1,934)
Balance at September 30, 2024	$	1,005

Our liability for the MSKCC success payments is carried at fair value and changes are recognized as expense or income as part of other income until the success payments liability is paid or expires. We recorded a $0.2 million and $0.1 million change in the fair value of the MSKCC success payments liability as a loss in other income in our unaudited condensed consolidated statements of operations and comprehensive loss for the three months ended September 30, 2024, and 2023, respectively. We recorded a $1.9 million and $0.4 million change in the fair value of the MSKCC success payments liability as a gain in other income in our unaudited condensed consolidated statements of operations and comprehensive loss for the nine months ended September 30, 2024, and 2023, respectively.

The table below summarizes key assumptions used in the valuation of the MSKCC success payments liability:


	As of December 31, 2023
Fair value of common stock	$	5.73
Risk-free interest rate	3.88%
Expected volatility	79%
Probability of achieving multiple of Initial Share Price(1)	5.2% to 18.1%
Expected term (years)	3.7 to 5.2

The computation of expected volatility was estimated using a combination of available information about the historical volatility of stocks of similar publicly traded companies for a period matching the expected term assumption and the historical and implied volatility of our stock. The risk-free interest rate, expected volatility, and expected term assumptions depend on the time period from the initiation of our AMpLify phase 1 clinical trial for our CB-012 product candidate utilizing the know-how, biological materials, and intellectual property licensed under the Exclusive License Agreement, dated November 13, 2020, with MSKCC (“MSKCC Agreement”) until the estimated timing of marketing approval for this product candidate from the U.S. Food and Drug Administration (“FDA”). In addition, we incorporated the estimated number and timing of valuation measurement dates in the calculation of the MSKCC success payments liability.

As of September 30, 2024, we did not note any significant changes to the inputs used in the MSKCC success payments liability fair value calculation, other than a change in the fair value of our common stock to $1.96 per share.

- 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.

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+ Details