0001558370-25-007803 | 10-Q | XBRL Viewer

Net Loss Per Share

3 Months Ended

Mar. 31, 2025

11.Net Loss Per Share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts):


	Three Months Ended March 31,
	2025		2024
Numerator:
Net loss attributable to common stockholders	$	(33,573)	$	(27,800)
Denominator:
Weighted-average common stock outstanding - basic and diluted		41,800,802		1,554,087
Net loss per share attributable to common stockholders - basic and diluted	$	(0.80)	$	(17.89)

The Company’s potentially dilutive securities, which include convertible preferred stock, restricted stock and stock options, have been excluded from the computation of diluted net loss per share as the effect would be to reduce the net loss per share. Therefore, the weighted-average number of common shares outstanding used to calculate both basic and diluted net loss per share attributable to common stockholders is the same. The Company excluded the following shares from the computation of diluted net loss per share attributable to common stockholders as of March 31, 2025 and 2024 because including them would have had an anti-dilutive effect:


	March 31,
	2025	2024
Convertible preferred stock	—	100,617,681
Unvested restricted stock	—	3,767
Options to purchase common stock	8,670,569	2,403,183

Accrued Expenses

3 Months Ended

Mar. 31, 2025

Accrued Expenses

Accrued Expenses

5.Accrued Expenses

Accrued expenses consisted of the following (in thousands):



	March 31, 2025		December 31, 2024
External research, development and manufacturing expenses	$	23,588	$	29,338
Employee compensation and benefits		3,383		8,308
Professional and consultant fees		846		1,265
Income taxes payable		5		211
Other		384		249
Total accrued expenses	$	28,206	$	39,371

Net Loss Per Share - Anti-dilutive Securities (Details) - shares	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Convertible preferred stock
Net Loss Per Share
Anti-dilutive securities excluded from computation of diluted net (loss) per share		100,617,681
Unvested restricted stock
Net Loss Per Share
Anti-dilutive securities excluded from computation of diluted net (loss) per share		3,767
Options to purchase common stock
Net Loss Per Share
Anti-dilutive securities excluded from computation of diluted net (loss) per share	8,670,569	2,403,183

License Agreements	3 Months Ended
Mar. 31, 2025
License Agreements
License Agreements	8.License Agreements License Agreements with Xencor, Inc. 2020 Xencor Agreement In September 2020, the Company entered into a license agreement (the “2020 Xencor Agreement”) with Xencor, Inc. (“Xencor”), under which the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products, including ZB002 and ZB004. The royalty percentage rates vary by geographic areas as defined in the 2020 Xencor Agreement and range from the mid-single digits to mid-teens. The Company is also obligated to reimburse Xencor for third-party costs incurred for certain patent filings, prosecution and maintenance as further specified in the 2020 Xencor Agreement. During the three months ended March 31, 2025 and 2024, the Company incurred no such reimbursable costs. 2021 Xencor Agreement In May 2021, the Company entered into a license agreement with Xencor (the “2021 Xencor Agreement”), under which the Company obtained an exclusive, royalty-bearing, sublicensable worldwide license to research, develop, manufacture, market and sell obexelimab. The Company is also obligated to make regulatory milestone payments up to $75.0 million and one-time sales milestone payments up to $385.0 million upon achieving milestone events of net sales in a given calendar year in the territory equal to certain threshold amounts. In addition, the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products utilizing obexelimab, with the royalty percentages varying based on regions and ranging from the mid-single digits to the mid-teens. For the three months ended March 31, 2025 and 2024, the Company recorded no reimbursable patent-related costs, respectively. License Agreement with Viridian Therapeutics, Inc. In October 2020, the Company entered into a license agreement with Viridian Therapeutics, Inc. (the “Viridian Agreement”) to obtain an exclusive, royalty-bearing, sublicensable license to research, develop, manufacture, market and sell certain antibody product candidates based on Viridian’s proprietary technology. The Company’s license rights are limited to non-oncology indications and are limited to China, Hong Kong, Macau and Taiwan (“Zenas Territories”). Viridian retains its rights to develop and commercialize such product candidates outside of the Zenas Territories. In December 2021, the Company and Viridian entered into two letter agreements to authorize initiation of certain manufacturing and development activities related to the licensed product candidate, ZB001. Under the terms of the letter agreements, Viridian engaged a third-party contract manufacturer to initiate certain work related to ZB001. In May 2022, the Company entered into a manufacturing development and supply agreement (“Viridian Supply Agreement”). In January 2025, the Company entered into a third amendment to the Viridian Agreement, under which the Company is obligated to make development and sales milestone payments to Viridian, totaling $21.0 million, based on achievement of certain specified development and sales milestones, and royalties on net sales. In January 2025, the Company entered the Zai License Agreement under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. In connection with the Zai License Agreement, the Company assigned the Viridian Supply Agreement to Zai. For additional information on the Zai Agreement, please see License Agreement with Zai Lab (Hong Kong) Limited in Note 7 – License and Collaboration Revenue to these condensed consolidated financial statements. During the three months ended March 31, 2025 and 2024, the Company recognized no expense related to Viridian contract manufacturing organization (“CMO”) costs. Viridian has agreed to reimburse the Company for certain services the Company performs on Viridian’s behalf, with reimbursements being recorded as a reduction in research and development expenses. During the three months ended March 31, 2025, the Company recorded $0.1 million in reimbursable expenses. During the three months ended March 31, 2024, the Company had no reimbursable expenses. Additionally, during the three months ended March 31, 2025 and 2024, no milestones were achieved.

License Agreements

3 Months Ended

Mar. 31, 2025

License Agreements

License Agreements

8.License Agreements

License Agreements with Xencor, Inc.

2020 Xencor Agreement

In September 2020, the Company entered into a license agreement (the “2020 Xencor Agreement”) with Xencor, Inc. (“Xencor”), under which the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products, including ZB002 and ZB004. The royalty percentage rates vary by geographic areas as defined in the 2020 Xencor Agreement and range from the mid-single digits to mid-teens. The Company is also obligated to reimburse Xencor for third-party costs incurred for certain patent filings, prosecution and maintenance as further specified in the 2020 Xencor Agreement. During the three months ended March 31, 2025 and 2024, the Company incurred no such reimbursable costs.

2021 Xencor Agreement

In May 2021, the Company entered into a license agreement with Xencor (the “2021 Xencor Agreement”), under which the Company obtained an exclusive, royalty-bearing, sublicensable worldwide license to research, develop, manufacture, market and sell obexelimab. The Company is also obligated to make regulatory milestone payments up to $75.0 million and one-time sales milestone payments up to $385.0 million upon achieving milestone events of net sales in a given calendar year in the territory equal to certain threshold amounts. In addition, the Company is required to pay Xencor tiered royalties on annual net sales of successfully commercialized products utilizing obexelimab, with the royalty percentages varying based on regions and ranging from the mid-single digits to the mid-teens.

For the three months ended March 31, 2025 and 2024, the Company recorded no reimbursable patent-related costs, respectively.

License Agreement with Viridian Therapeutics, Inc.

In October 2020, the Company entered into a license agreement with Viridian Therapeutics, Inc. (the “Viridian Agreement”) to obtain an exclusive, royalty-bearing, sublicensable license to research, develop, manufacture, market and sell certain antibody product candidates based on Viridian’s proprietary technology. The Company’s license rights are limited to non-oncology indications and are limited to China, Hong Kong, Macau and Taiwan (“Zenas Territories”). Viridian retains its rights to develop and commercialize such product candidates outside of the Zenas Territories. In December 2021, the Company and Viridian entered into two letter agreements to authorize initiation of certain manufacturing and development activities related to the licensed product candidate, ZB001. Under the terms of the letter agreements, Viridian engaged a third-party contract manufacturer to initiate certain work related to ZB001. In May 2022, the Company entered into a manufacturing development and supply agreement (“Viridian Supply Agreement”). In January 2025, the Company entered into a third amendment to the Viridian Agreement, under which the Company is obligated to make development and sales milestone payments to Viridian, totaling $21.0 million, based on achievement of certain specified development and sales milestones, and royalties on net sales.

In January 2025, the Company entered the Zai License Agreement under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. In connection with the Zai License Agreement, the Company assigned the Viridian Supply Agreement to Zai. For additional information on the Zai Agreement, please see License Agreement with Zai Lab (Hong Kong) Limited in Note 7 – License and Collaboration Revenue to these condensed consolidated financial statements.

During the three months ended March 31, 2025 and 2024, the Company recognized no expense related to Viridian contract manufacturing organization (“CMO”) costs. Viridian has agreed to reimburse the Company for certain services the Company performs on Viridian’s behalf, with reimbursements being recorded as a reduction in research and development expenses. During the three months ended March 31, 2025, the Company recorded $0.1 million in reimbursable expenses. During the three months ended March 31, 2024, the Company had no reimbursable expenses. Additionally, during the three months ended March 31, 2025 and 2024, no milestones were achieved.

Stock-Based Compensation - Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Stock-Based Compensation Expense
Total stock-based compensation expense	$ 5,386	$ 947
Research and development
Stock-Based Compensation Expense
Total stock-based compensation expense	1,581	411
General and administrative
Stock-Based Compensation Expense
Total stock-based compensation expense	$ 3,805	$ 536

License Agreements (Details) - USD ($) $ in Millions	3 Months Ended
License Agreements (Details) - USD ($) $ in Millions	Mar. 31, 2025	Mar. 31, 2024	Jan. 31, 2025	May 31, 2021
2020 Xencor Agreement
Nature of Business
Agreement transaction price	$ 0.0	$ 0.0
2021 Xencor Agreement
Nature of Business
Reimbursable costs	0.0	0.0
Regulatory milestone payments				$ 75.0
Sales milestone payments				$ 385.0
Viridian Agreement
Nature of Business
Reimbursable costs	0.1	0.0
Development milestone expense payable			$ 21.0
Sales milestone payments			$ 21.0
Contract manufacturing organization costs recognized	$ 0.0	$ 0.0

Net Loss Per Share (Tables)

3 Months Ended

Mar. 31, 2025

Net Loss Per Share

Schedule of basic and diluted net loss per share

Basic and diluted net loss per share attributable to common stockholders was calculated as follows (in thousands, except share and per share amounts):


	Three Months Ended March 31,
	2025		2024
Numerator:
Net loss attributable to common stockholders	$	(33,573)	$	(27,800)
Denominator:
Weighted-average common stock outstanding - basic and diluted		41,800,802		1,554,087
Net loss per share attributable to common stockholders - basic and diluted	$	(0.80)	$	(17.89)

Schedule of anti-dilutive securities excluded from the computation of diluted net loss per share


	March 31,
	2025	2024
Convertible preferred stock	—	100,617,681
Unvested restricted stock	—	3,767
Options to purchase common stock	8,670,569	2,403,183

Net Loss Per Share - Basic and diluted (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Numerator:
Net loss to common stockholders	$ (33,573)	$ (27,800)
Denominator:
Weighted-average common stock outstanding - basic (in shares)	41,800,802	1,554,087
Weighted-average common stock outstanding - diluted (in shares)	41,800,802	1,554,087
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.8)	$ (17.89)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.8)	$ (17.89)

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-6

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 60
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147476176/805-60-65-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 323
-Name Accounting Standards Codification
-Section 65
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478666/740-323-65-2

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(20))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483621/220-10-S99-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(g)(1)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 323
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481687/323-10-50-3

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 825
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 28
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482907/825-10-50-28

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482765/220-10-50-6

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 65
-Paragraph 1
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480175/815-40-65-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 8
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-8

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 11
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-11

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 250
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483443/250-10-50-4

Reference 17: http://www.xbrl.org/2003/role/exampleRef
-Topic 946
-SubTopic 830
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479168/946-830-55-10

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section 45
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479105/946-220-45-7

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(18))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477250/944-220-S99-1

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(9))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.6-09(1)(d))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-3

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 23: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(ii))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1A

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(A))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 29: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 30: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 31: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480097/470-10-S99-1B

Reference 32: http://www.xbrl.org/2003/role/disclosureRef
-Topic 260
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 60B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482689/260-10-45-60B

Reference 33: http://www.xbrl.org/2003/role/disclosureRef
-Topic 205
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 7
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483499/205-20-50-7

Reference 34: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1A

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1B
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482790/220-10-45-1B

Reference 37: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(22))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478524/942-220-S99-1

+ Details

Leases (Tables)

3 Months Ended

Mar. 31, 2025

Leases

Schedule of minimum lease payments under the Company's operating leases

The minimum lease payments under the Company’s operating leases are expected to be as follows (in thousands):


Fiscal Year	Amount
2025 (remaining nine months)	$	713
2026		453
2027		136
Thereafter		—
Total future minimum lease payments		1,302
Less: imputed interest		(77)
Total operating lease liabilities	$	1,225

Accrued Expenses (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Accrued Expenses
External research, development and manufacturing expenses	$ 23,588	$ 29,338
Employee compensation and benefits	3,383	8,308
Professional and consultant fees	846	1,265
Income taxes payable	5	211
Other	384	249
Total accrued expenses	$ 28,206	$ 39,371

Common Stock (Tables)

3 Months Ended

Mar. 31, 2025

Common Stock

Schedule of common stock reserved for potential conversion and future issuance


	March 31, 2025	December 31, 2024
Options to purchase common stock	8,670,569	8,706,197
Remaining shares reserved for future issuance	2,456,222	359,399
Employee stock purchase plan	815,890	397,956
Total	11,942,681	9,463,552

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Cash flows from operating activities:
Net Income (Loss)	$ (33,573)	$ (27,800)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation expense	23	33
Loss on disposal of property and equipment	107
Net amortization of premiums and accretion of discounts on investments	(382)
Stock-based compensation expense	5,386	947
Change in fair value of convertible notes		694
Non-cash lease expense	246	159
Prepaid expenses and other assets	(353)	1,787
Accounts payable	2,882	3,407
Accrued expenses	(11,165)	335
Operating lease liabilities	(222)	(164)
Other current liabilities		1,500
Net cash used in operating activities	(37,051)	(19,102)
Cash flows from investing activities:
Purchases of property and equipment	(18)	(22)
Purchases of investments	(99,114)
Proceeds from sales and maturities of investments	12,858
Net cash used in investing activities	(86,274)	(22)
Cash flows from financing activities:
Payment of initial public offering costs		(656)
Proceeds from exercise of stock options	99	42
Net cash provided by (used in) financing activities	99	(614)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(52)	36
Net decrease in cash, cash equivalents and restricted cash	(123,278)	(19,702)
Cash, cash equivalents and restricted cash at beginning of period	319,832	56,942
Cash, cash equivalents and restricted cash at end of period	196,554	37,240
Supplemental disclosure of non-cash investing and financing activities:
Right-of-use assets obtained under operating lease arrangements	$ 445
Deferred offering costs in accounts payable and accrued expenses		$ 1,872

Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Other Assets
Clinical trial deposits	$ 12,639	$ 12,639
Other	209	217
Total other assets	$ 12,848	$ 12,856

Fair Value Measurements - Available-for-sale securities (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Fair Value Measurements
Amortized Cost	$ 117,617	$ 30,993
Gross Unrealized Gains	51	33
Gross Unrealized Losses	(8)	(2)
Fair Value	117,660	31,024
Commercial paper
Fair Value Measurements
Amortized Cost	6,378	3,311
Gross Unrealized Gains	9	4
Fair Value	6,387	3,315
Corporate debt securities
Fair Value Measurements
Amortized Cost	47,228	8,589
Gross Unrealized Gains	29	12
Gross Unrealized Losses	(4)
Fair Value	47,253	8,601
Government securities
Fair Value Measurements
Amortized Cost	64,011	19,093
Gross Unrealized Gains	13	17
Gross Unrealized Losses	(4)	(2)
Fair Value	$ 64,020	$ 19,108

Fair Value Measurements - Fair Value Transfers (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024
Fair Value Measurements
Assets - Transfer from level 1 to 2	$ 0	$ 0
Assets - Transfer from level 2 to 1	0	0
Assets - Transfer into level 3	0	0
Liabilities - Transfer from level 1 to 2	0	0
Liabilities - Transfer from level 2 to 1	0	0
Liabilities - Transfer into level 3	0	0
Realized gain (loss) recognized on the sale or maturity of available-for-sale	$ 0	$ 0
Minimum
Fair Value Measurements
Remaining contractual maturities	1 month
Maximum
Fair Value Measurements
Remaining contractual maturities	18 months

Nature of Business (Details) $ / shares in Units, $ in Thousands		3 Months Ended
	Sep. 16, 2024 USD ($) $ / shares shares	Mar. 31, 2025 USD ($) segment	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Nature of Business
Number of operating segments \| segment		1
Net loss		$ 33,573	$ 27,800
Accumulated deficit		420,964		$ 387,391
Cash, cash equivalents and investments		$ 314,200
IPO
Nature of Business
Issuance of common stock (in shares) \| shares	15,220,588
Public offering price \| $ / shares	$ 17
Aggregate gross proceeds	$ 258,700
Net proceeds	$ 234,300
Convertible preferred stock into common stock \| shares	24,978,715
Reverse stock split	0.1152
Underwriter's option
Nature of Business
Issuance of common stock (in shares) \| shares	1,985,294

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2025

Summary of Significant Accounting Policies

Summary of Significant Accounting Policies

2.Summary of Significant Accounting Policies

The Company’s significant accounting policies are disclosed in Note 2, Summary of Significant Accounting Policies, in the audited consolidated financial statements for the year ended December 31, 2024, and notes thereto, included in the Company’s Annual Report on Form 10-K that was filed with the SEC on March 11, 2025. Since the date of those financial statements, there have been no material changes to the Company’s significant accounting policies.

Basis of Presentation and Consolidation

The accompanying condensed consolidated financial statements include the operations of the Company and its wholly-owned subsidiaries. All intercompany accounts, transactions, and balances have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been or omitted pursuant to such rules and regulations.

Unaudited Interim Financial Information

The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited financial statements and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2025, and the results of operations and its cash flows for the three months ended March 31, 2025 and 2024. The financial data and other information disclosed in these notes related to the three months ended March 31, 2025 and 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2025, any other interim periods, or any future year or period. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2024, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K as filed with the SEC, on March 11, 2025.

Use of Estimates

The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, expenses, and related disclosures. The Company bases its estimates on historical experience, known trends and other market-specific factors or other relevant factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis using such factors and adjusts those estimates and assumptions as facts and circumstances dictate. Actual results may differ from those estimates or assumptions. Significant estimates in these condensed consolidated financial statements include estimates made in connection with accrued research and development expenses, stock-based compensation and pre-initial public offering (“IPO”) valuations of common stock.

Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgement. As of the date of the issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgements or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s financial statements.

Recent Accounting Pronouncements

From time to time, new accounting pronouncements are issued by the “FASB” or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed, we do not believe that the adoption of recently issued standards have or may have a material impact on our condensed consolidated statements or disclosures.

Related Party Transactions (Details) - Related party	3 Months Ended	12 Months Ended
Related Party Transactions (Details) - Related party	Mar. 31, 2025 item	Dec. 31, 2020 shares
Xencor
Related Party Transactions
Number of antibody product candidates	3
Number of license agreements	2
Xencor \| Maximum
Related Party Transactions
Ownership percentage by related party	10.00%
Viridian
Related Party Transactions
Ownership percentage by related party	0.10%
Number of common stock issued \| shares		38,707
Viridian \| Fairmount Funds Management LLC
Related Party Transactions
Number of seats held in board	2
Viridian \| Fairmount Funds Management LLC \| Maximum
Related Party Transactions
Ownership percentage by related party	10.00%

Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
Segment Information (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Mar. 31, 2024
Segment Information
Revenue	$ 10,000
Research and development expenses	(34,915)	$ (22,645)
General and administrative	(12,415)	(4,933)
Stock-based compensation	(5,386)	(947)
Net loss to common stockholders	(33,573)	(27,800)
Single Reportable Segment
Segment Information
Revenue	10,000
General and administrative	8,610	4,397
Stock-based compensation	5,386	947
Other segment items	(3,757)	222
Net loss to common stockholders	$ (33,573)	$ (27,800)
Other segment items, description	Other segment items consist of other income (expense), net and income tax benefit (provision). Other income (expense), net consists of interest income and realized and unrealized gains and losses on foreign currency transactions	Other segment items consist of other income (expense), net and income tax benefit (provision). Other income (expense), net consists of interest income and realized and unrealized gains and losses on foreign currency transactions
Single Reportable Segment \| Obexelimab
Segment Information
Research and development expenses	$ 23,491	$ 12,295
Single Reportable Segment \| Other programs (ZB002 & ZB004)
Segment Information
Research and development expenses	203	894
Single Reportable Segment \| Partnered regional programs (ZB001 & ZB005)
Segment Information
Research and development expenses	99	1,588
Single Reportable Segment \| Unallocated
Segment Information
Research and development expenses	$ 9,541	$ 7,457

Stock-Based Compensation (Details) - shares			1 Months Ended	3 Months Ended
Stock-Based Compensation (Details) - shares	Jan. 01, 2025	Sep. 03, 2024	Jan. 31, 2025	Mar. 31, 2025	Dec. 31, 2024
Stock-Based Compensation
Number of common stock remain available for future grant				11,942,681	9,463,552
2024 Plan
Stock-Based Compensation
Maximum additional number of outstanding capital stock percent		5.00%
Increase in common stock available for issuance			2,089,670
Number of common stock remain available for future grant				2,456,222
2024 ESPP
Stock-Based Compensation
Maximum additional number of outstanding capital stock percent		1.00%
Increase in common stock available for issuance	417,934
Number of common stock remain available for future grant				815,890
Additional shares To Be authorized		1,000,000
Shares issued under ESPP				0

- Definition

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

+ References

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

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

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(1)(iv)(04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(01)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(02)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(03)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(ii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 26: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iii)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 27: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(iv)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

Reference 28: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(v)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

Condensed Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	$ 196,554	$ 319,742	$ 37,154
Restricted cash		90	86
Total cash, cash equivalents and restricted cash	$ 196,554	$ 319,832	$ 37,240	$ 56,942

Stock-Based Compensation

3 Months Ended

Mar. 31, 2025

Stock-Based Compensation

Stock-Based Compensation

10.Stock-Based Compensation

2024 Plan

On September 3, 2024, the Board of Directors (the “Board”) adopted the 2024 Equity Incentive Plan (the “2024 Plan”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s IPO. The 2024 Plan provides for the award of incentive stock options, nonstatutory stock options, stock appreciation rights, restricted stock awards, unrestricted stock, restricted stock units and other stock-based awards.

The number of shares reserved and available for issuance under the 2024 Plan will automatically increase each January 1, beginning on January 1, 2025 through January 1, 2034, by the number of shares equal to the lesser of (i) five percent of the aggregate number of shares of common stock outstanding as of such date, and (ii) a number of shares as may be determined by the Board on or prior to such date. In January 2025, the number of shares of common stock available for issuance under the Company’s 2024 Plan, was increased by 2,089,670 shares of common stock due to the automatic annual provision to increase shares of common stock available under the 2024 Plan. As of March 31, 2025, 2,456,222 shares of common stock were available for issuance under the 2024 Plan.

Stock Options

The Company has granted stock-based awards with either service or performance based vesting conditions. Compensation expense related to awards to employees and directors with service based vesting conditions is recognized on a straight-line basis based on the grant date fair value over the associated service period of the award, which is generally the vesting term. Compensation expense related to awards to employees with performance based vesting conditions is recognized based on the grant date fair value once the achievement of the performance condition is probable.

The following table presents a summary of the Company’s stock option activity and related information:




	Number of Shares	Weighted - Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding - December 31, 2024	8,706,197	$	13.21		$	2,104
Granted	108,000	$	7.28
Exercised	(28,475)	$	3.48		$	136
Forfeited or cancelled	(115,153)	$	13.94
Outstanding - March 31, 2025	8,670,569	$	13.16	8.53	$	1,877
Options vested and exercisable as of March 31, 2025	1,434,494	$	7.93	5.62	$	1,708
Options vested and expected to vest as of March 31, 2025	8,670,569	$	13.16	8.53	$	1,877

The aggregate intrinsic value of the stock options is calculated as the difference between the exercise price of the options and the fair value of the Company’s common stock for those stock options that had an exercise price lower than the fair value of the Company’s common stock as of the measurement date of March 31, 2025.

As of March 31, 2025, there was $68.4 million of unrecognized stock-based compensation related to stock options, which is expected to be recognized over a weighted-average period of 3.15 years.

The Company recognized stock-based compensation expense related to the issuance of equity awards to employees and directors in the condensed consolidated statement of operations as follows (in thousands):


		Three Months Ended March 31,
		2025		2024
Research and development	$	1,581	$	411
General and administrative		3,805		536
Total stock-based compensation expense	$	5,386	$	947

Employee Stock Purchase Plan

On September 3, 2024, the Board adopted the 2024 Employee Stock Purchase Plan (the “ESPP”), which became effective immediately prior to the effectiveness of the registration statement for the Company’s IPO. The number of shares of common stock available under the ESPP will automatically increase on January 1st of each year, beginning on January 1, 2025 through January 1, 2034, by the number of shares equal to the lesser of (i) one percent of the aggregate number of shares of common stock outstanding as of such date, and (ii) a number of shares as may be determined by the Board on or prior to such date, up to a maximum of 1,000,000 shares in the aggregate per year. On January 1, 2025, the number of shares of common stock authorized for issuance under the ESPP increased automatically by 417,934 shares and as of March 31, 2025, a total of 815,890 shares were available for future issuance under the ESPP. There were no shares issued under the ESPP during the three months ended March 31, 2025.

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Mar. 31, 2025	Dec. 31, 2024
Condensed Consolidated Balance Sheets
Preferred stock, par value (in dollar per share)	$ 0.0001	$ 0.0001
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollar per share)	$ 0.0001	$ 0.0001
Common stock, shares authorized	175,000,000	175,000,000
Common stock, shares issued	41,821,887	41,793,412
Common Stock, shares outstanding	41,821,887	41,793,412

Stock-Based Compensation (Tables)

3 Months Ended

Mar. 31, 2025

Stock-Based Compensation

Schedule of stock option activity and related information




	Number of Shares	Weighted - Average Exercise Price		Weighted-Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding - December 31, 2024	8,706,197	$	13.21		$	2,104
Granted	108,000	$	7.28
Exercised	(28,475)	$	3.48		$	136
Forfeited or cancelled	(115,153)	$	13.94
Outstanding - March 31, 2025	8,670,569	$	13.16	8.53	$	1,877
Options vested and exercisable as of March 31, 2025	1,434,494	$	7.93	5.62	$	1,708
Options vested and expected to vest as of March 31, 2025	8,670,569	$	13.16	8.53	$	1,877

Schedule of stock-based compensation expense as reflected in consolidated statements of operations


		Three Months Ended March 31,
		2025		2024
Research and development	$	1,581	$	411
General and administrative		3,805		536
Total stock-based compensation expense	$	5,386	$	947

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2025
Summary of Significant Accounting Policies
Basis of Presentation and Consolidation	Basis of Presentation and Consolidation The accompanying condensed consolidated financial statements include the operations of the Company and its wholly-owned subsidiaries. All intercompany accounts, transactions, and balances have been eliminated in consolidation. The accompanying condensed consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Update (“ASU”) of the Financial Accounting Standards Board (“FASB”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been or omitted pursuant to such rules and regulations.
Unaudited Interim Financial Information	Unaudited Interim Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared on the same basis as the annual audited financial statements and in the opinion of management, reflect all adjustments, which include only normal recurring adjustments, necessary for the fair statement of the Company’s financial position as of March 31, 2025, and the results of operations and its cash flows for the three months ended March 31, 2025 and 2024. The financial data and other information disclosed in these notes related to the three months ended March 31, 2025 and 2024 are not necessarily indicative of the results to be expected for the year ending December 31, 2025, any other interim periods, or any future year or period. These interim financial statements should be read in conjunction with the audited financial statements as of and for the year ended December 31, 2024, and the notes thereto, which are included in the Company’s Annual Report on Form 10-K as filed with the SEC, on March 11, 2025.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions that affect the reported amounts of assets, liabilities, expenses, and related disclosures. The Company bases its estimates on historical experience, known trends and other market-specific factors or other relevant factors that it believes to be reasonable under the circumstances. The Company evaluates its estimates and assumptions on an ongoing basis using such factors and adjusts those estimates and assumptions as facts and circumstances dictate. Actual results may differ from those estimates or assumptions. Significant estimates in these condensed consolidated financial statements include estimates made in connection with accrued research and development expenses, stock-based compensation and pre-initial public offering (“IPO”) valuations of common stock. Estimates and assumptions about future events and their effects cannot be determined with certainty and therefore require the exercise of judgement. As of the date of the issuance of these financial statements, the Company is not aware of any specific event or circumstance that would require the Company to update its estimates, assumptions and judgements or revise the carrying value of its assets or liabilities. These estimates may change as new events occur and additional information is obtained and are recognized in the financial statements as soon as they become known. Actual results could differ from those estimates and any such differences may be material to the Company’s financial statements.
Recent Accounting Pronouncements	Recent Accounting Pronouncements From time to time, new accounting pronouncements are issued by the “FASB” or other standard setting bodies that we adopt as of the specified effective date. Unless otherwise discussed, we do not believe that the adoption of recently issued standards have or may have a material impact on our condensed consolidated statements or disclosures.

Fair Value Measurements - Valuation Techniques (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Short-term investments:
Short-term investments	$ 117,660	$ 31,024
Carrying value
Long-term investments:
Total assets	314,214	350,766
Cash \| Carrying value
Assets:
Assets	23,721	19,070
Money market funds \| Carrying value
Assets:
Assets	172,833	300,672
Commercial paper
Short-term investments:
Short-term investments	6,387	3,315
Commercial paper \| Carrying value
Short-term investments:
Short-term investments	6,387	3,315
Corporate debt securities
Short-term investments:
Short-term investments	47,253	8,601
Corporate debt securities \| Carrying value
Short-term investments:
Short-term investments	45,418	8,601
Long-term investments:
Long-term investments	1,835
Government securities
Short-term investments:
Short-term investments	64,020	19,108
Government securities \| Carrying value
Short-term investments:
Short-term investments	64,020	19,108
Level 1 \| Estimate of fair value measurement
Long-term investments:
Total assets	260,574	338,850
Level 1 \| Cash \| Estimate of fair value measurement
Assets:
Assets	23,721	19,070
Level 1 \| Money market funds \| Estimate of fair value measurement
Assets:
Assets	172,833	300,672
Level 1 \| Government securities \| Estimate of fair value measurement
Short-term investments:
Short-term investments	64,020	19,108
Level 2 \| Estimate of fair value measurement
Long-term investments:
Total assets	53,640	11,916
Level 2 \| Commercial paper \| Estimate of fair value measurement
Short-term investments:
Short-term investments	6,387	3,315
Level 2 \| Corporate debt securities \| Estimate of fair value measurement
Short-term investments:
Short-term investments	45,418	$ 8,601
Long-term investments:
Long-term investments	$ 1,835

Accrued Expenses (Tables)

3 Months Ended

Mar. 31, 2025

Accrued Expenses

Summary of accrued expenses

Accrued expenses consisted of the following (in thousands):



	March 31, 2025		December 31, 2024
External research, development and manufacturing expenses	$	23,588	$	29,338
Employee compensation and benefits		3,383		8,308
Professional and consultant fees		846		1,265
Income taxes payable		5		211
Other		384		249
Total accrued expenses	$	28,206	$	39,371

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Revenue:
License and collaboration revenue	$ 10,000
Total revenue	10,000
Operating expenses:
Research and development	34,915	$ 22,645
General and administrative	12,415	4,933
Total operating expenses	47,330	27,578
Loss from operations	(37,330)	(27,578)
Other income (expense), net:
Fair value adjustments to convertible notes		(694)
Other income, net	3,552	472
Total other income (expense), net	3,552	(222)
Loss before income taxes	(33,778)	(27,800)
Income tax benefit	205
Net loss to common stockholders	$ (33,573)	$ (27,800)
Net loss per share attributable to common stockholders - basic (in dollars per share)	$ (0.8)	$ (17.89)
Net loss per share attributable to common stockholders - diluted (in dollars per share)	$ (0.8)	$ (17.89)
Weighted-average common stock outstanding - basic (in shares)	41,800,802	1,554,087
Weighted-average common stock outstanding - diluted (in shares)	41,800,802	1,554,087
Comprehensive loss:
Net loss to common stockholders	$ (33,573)	$ (27,800)
Other comprehensive income (loss):
Unrealized gain on investments	12
Foreign currency translation adjustment	(65)	37
Comprehensive loss	$ (33,626)	$ (27,763)

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Mar. 31, 2025
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2025

Fair Value Measurements

Schedule of information about the Company's assets and liabilities that are regularly measured and carried at fair value

The following table presents information about the Company’s assets and liabilities that are regularly measured and carried at fair value and indicate the level within the fair value hierarchy of the valuation techniques the Company utilized to determine such fair value (in thousands):


		As of March 31, 2025
Description		Total Carrying Value		Quoted Prices in Active Market (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Observable Inputs (Level 3)
Assets:
Cash	$	23,721	$	23,721	$	—	$	—
Money market funds		172,833		172,833		—		—
Short-term investments:
Commercial paper		6,387		—		6,387		—
Corporate debt securities		45,418		—		45,418		—
Government securities		64,020		64,020		—		—
Long-term investments:
Corporate debt securities		1,835		—		1,835		—
Total assets	$	314,214	$	260,574	$	53,640	$	—


		As of December 31, 2024
Description		Total Carrying Value		Quoted Prices in Active Market (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Observable Inputs (Level 3)
Assets:
Cash	$	19,070	$	19,070	$	—	$	—
Money market funds		300,672		300,672		—		—
Short-term investments:
Commercial paper		3,315		—		3,315		—
Corporate debt securities		8,601		—		8,601		—
Government securities		19,108		19,108		—		—
Total assets	$	350,766	$	338,850	$	11,916	$	—

Summary of available-for-sale securities

The following table summarizes the available-for-sale securities (in thousands):


	As of March 31, 2025
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
March 31, 2025
Commercial paper	$	6,378	$	9	$	—	$	6,387
Corporate debt securities		47,228		29		(4)		47,253
Government securities		64,011		13		(4)		64,020
Total	$	117,617	$	51	$	(8)	$	117,660


	As of December 31, 2024
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2024
Commercial paper	$	3,311	$	4	$	—	$	3,315
Corporate debt securities		8,589		12		—		8,601
Government securities		19,093		17		(2)		19,108
Total	$	30,993	$	33	$	(2)	$	31,024

- Definition

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

+ References

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

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

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

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

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

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

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

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

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

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

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

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

+ Details

Condensed Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income	Accumulated Deficit	Series Seed convertible preferred stock	Series A convertible preferred stock	Series B convertible preferred stock	Total
Balance at beginning at Dec. 31, 2023					$ 956	$ 55,840	$ 193,290
Balance at beginning (in shares) at Dec. 31, 2023					1,785,714	17,589,380	81,242,587
Balance at end at Mar. 31, 2024					$ 956	$ 55,840	$ 193,290
Balance at the end (in shares) at Mar. 31, 2024					1,785,714	17,589,380	81,242,587
Balance at the beginning at Dec. 31, 2023		$ 4,645	$ 37	$ (230,403)				$ (225,721)
Balance at beginning (in shares) at Dec. 31, 2023	1,576,854
Changes in Stockholders' Equity (Deficit)
Repurchase of unvested restricted stock awards (in shares)	(21,172)
Exercises of common stock options		42						42
Exercises of common stock options (in shares)	7,035
Stock-based compensation expense		947						947
Foreign currency translation adjustment			37					37
Net Income (Loss)				(27,800)				(27,800)
Balance at end at Mar. 31, 2024		5,634	74	(258,203)				(252,495)
Balance at end (in shares) at Mar. 31, 2024	1,562,717
Balance at the beginning at Dec. 31, 2024	$ 4	699,651	194	(387,391)				312,458
Balance at beginning (in shares) at Dec. 31, 2024	41,793,412
Changes in Stockholders' Equity (Deficit)
Exercises of common stock options		99						$ 99
Exercises of common stock options (in shares)	28,475							28,475
Stock-based compensation expense		5,386						$ 5,386
Unrealized gain on investments			12					12
Foreign currency translation adjustment			(65)					(65)
Net Income (Loss)				(33,573)				(33,573)
Balance at end at Mar. 31, 2025	$ 4	$ 705,136	$ 141	$ (420,964)				$ 284,317
Balance at end (in shares) at Mar. 31, 2025	41,821,887

Segment Information

3 Months Ended

Mar. 31, 2025

Segment Information

Segment Information

14.Segment Information

The Company manages its operations on a consolidated basis as a single reportable segment focused on the research and development of precision immunology-based therapies. The accounting policies of the single reportable segment are identical to those described in Note 2, Summary of Significant Accounting Policies. When evaluating the Company’s financial performance, the Company’s chief operating decision-maker (the “CODM”), its Chief Executive Officer regularly reviews consolidated net loss, total expense and direct expenses by program and compared to budget. The CODM

allocates resources based on the Company’s available cash resources, forecasted expenditures on a consolidated basis, as well as an assessment of the probability of success of its research and development activities on a program basis. Segment asset information regularly provided to the CODM is consistent with that reported on the consolidated balance sheets with particular emphasis on the Company’s available liquidity, including its cash, cash equivalents and marketable securities balances. Revenue is primarily attributed to individual countries based on the entity owning the license, During the three months ended March 31, 2025, revenue was attributed to Zenas HK. The Company did not recognize revenue during the three months ended March 31, 2024.

The following table presents certain financial data for the Company’s reportable segments for the three months ended March 31, 2025 and 2024 (in thousands):


		March 31,
		2025		2024
Revenue	$	10,000	$	-
Less:
Direct research and development expenses:¹
Obexelimab		23,491		12,295
Other programs (ZB002 & ZB004)		203		894
Partnered regional programs (ZB001 & ZB005)		99		1,588
Unallocated research and development²		9,541		7,457
General and administrative³		8,610		4,397
Stock-based compensation		5,386		947
Other segment items⁴		(3,757)		222
Segment net loss	$	(33,573)	$	(27,800)

¹Direct research and development expenses primarily consist of direct costs incurred to specific program research and development activities, including costs to conduct clinical trials and to manufacture clinical drug supply.

² Unallocated research and development expenses primarily consist of indirect costs incurred in support of overall research and development activities and non-specific programs, including activities that benefit multiple programs, such as personnel costs for employees involved in research and development activities, excluding stock-based compensation, as well as contract services not allocated to specific programs.

³General and administrative expenses primarily consist of professional fees, depreciation expense, facilities expenses as well as all other personnel costs, excluding stock-based compensation.

⁴ Other segment items consist of other income (expense), net and income tax benefit (provision). Other income (expense), net consists of interest income and realized and unrealized gains and losses on foreign currency transactions.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (ee)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 5: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 9: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 54
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-54

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 47
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-47

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-31

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-34

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26C
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26C

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26B
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26B

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-15

Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-42

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-40

Reference 20: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/280/tableOfContent

Reference 21: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-26

Reference 22: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

Reference 23: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-21

Reference 24: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-21

Reference 25: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

+ Details

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Mar. 31, 2025	Mar. 31, 2024
Pay vs Performance Disclosure
Net Income (Loss)	$ (33,573)	$ (27,800)

- Definition

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

+ References

+ Details

Commitments and Contingencies (Details) $ in Millions	Mar. 31, 2025 USD ($)
Commitments and Contingencies
Contract payment obligation	$ 18.4

Leases - Maturities of Operating Lease Liabilities and Quantitative Disclosure (Details) $ in Thousands	Mar. 31, 2025 USD ($)
Maturities of the operating lease liabilities
2025 (remaining nine months)	$ 713
2026	453
2027	136
Total future minimum lease payments	1,302
Less: imputed interest	(77)
Total operating lease liabilities	$ 1,225

Commitments and Contingencies

3 Months Ended

Mar. 31, 2025

Commitments and Contingencies

Commitments and Contingencies

12.Commitments and Contingencies

Operating Leases

The Company has entered into arrangements for leases of office space; see Note 6, Leases, for details.

License Agreements

The Company entered into license agreements under which it is obligated to make fixed and contingent payments; see Note 8, License Agreements, for details.

Other Contracts

The Company has entered into agreements with certain vendors for the provision of services that the Company is not contractually able to terminate for convenience and thereby avoid any and all future obligations to the vendors. Under such agreements, the Company is contractually obligated to make certain minimum payments to the vendors, with the exact amounts in the event of termination to be based on the timing of the termination and the exact terms of the agreement. As of March 31, 2025, our total non-cancellable clinical manufacturing contract payment obligations are $18.4 million of which the full obligation is payable within 12 months.

Indemnification Agreements

In the ordinary course of business, the Company may provide indemnification of varying scope and terms to vendors, lessors, business partners and other parties with respect to certain matters including, but not limited to, losses arising out of breach of such agreements or from intellectual property infringement claims made by third parties. In addition, the Company has entered into indemnification agreements with members of its board of directors and certain officers that will require the Company, among other things, to indemnify them against certain liabilities that may arise by reason of their status or services as directors. The maximum potential amount of future payments the Company could be required to make under these indemnification agreements is, in many cases, unlimited. To date, the Company has not incurred any material costs as a result of such indemnifications. The Company is not currently aware of any indemnification claims and had not accrued any liabilities related to such obligations in its condensed consolidated financial statements as of March 31, 2025.

Litigation and Other Proceedings

The Company may periodically become subject to legal proceedings and claims arising in the ordinary course of business. As of March 31, 2025, the Company was not subject to any material legal proceedings which would reasonably be expected to have a material adverse effect on the Company’s financial results.

License and Collaboration Revenue

3 Months Ended

Mar. 31, 2025

License and Collaboration Revenue

License and Collaboration Revenue

7.License and Collaboration Revenue

License and Collaboration Agreement with Bristol-Myers Squibb

In August 2023, the Company entered into a license and collaboration agreement (the “BMS Agreement”) with BMS, under which the Company granted BMS an exclusive license to (i) develop, manufacture (subject to the Company’s rights to be the exclusive manufacturer for BMS for a certain period of time), commercialize or otherwise exploit obexelimab and any biological product (irrespective of presentations, formulations or dosages) containing obexelimab but not any of the Company’s other proprietary active ingredient (the “BMS Product”) into Japan, South Korea, Taiwan, Singapore, Hong Kong and Australia (collectively, the “BMS Territory”) and (ii) develop and manufacture obexelimab and the BMS Product outside the BMS Territory provided that obexelimab and the BMS Product are solely used in the BMS Territory.

Pursuant to the BMS Agreement, BMS paid the Company a one-time non-refundable upfront cash payment of $50.0 million. The Company is entitled to receive further separate development, regulatory milestone payments from BMS of up to approximately $79.5 million. The Company is also entitled to receive one-time sales milestone payments up to $70.0 million upon BMS achieving certain net sales milestones in a given year in the BMS Territory. The Company is also eligible to receive tiered high single-digit to low double-digit royalties on net sales in the BMS Territory, subject to specified reductions.

The Company will continue to perform and oversee the ongoing Phase 3 trial of obexelimab in the IgG4-RD indication and BMS will participate in the performance of the study. BMS will fund their pro rata share of the total global study costs up to a specified percentage of the patients enrolled in the study from the BMS Territory. Should the percentage of patients from the BMS Territory fall below the specified percentage, BMS’s funding would proportionately decrease. The global development activities under the agreement do not represent a transaction with a customer and reimbursement payments received by the Company for global development activities are accounted for as a reduction of the related research and development expenses.

For the three months ended March 31, 2025 and 2024, the Company recorded $1.7 million and $1.0 million, respectively, as a receivable included in prepaid expenses and other current assets. The Company recorded $1.7 million and $1.0 million for the three months ended March 31, 2025 and 2024, respectively, as a reduction to research and development expense for global development costs to be reimbursed by BMS. The Company did not recognize revenue related to the BMS Agreement during the three months ended March 31, 2025 and 2024.

Tenacia Biotechnology Co. Novation Agreement

In October 2024, the Company entered into a novation agreement with Tenacia Biotechnology (Hong Kong) Co., Limited (“Tenacia”), under which the Company transferred its rights and obligations under the agreements with Dianthus to Tenacia (the “Tenacia Agreement”). Pursuant to the Tenacia Agreement, the Company, transferred all the ZB005 inventory, analytical methods and manufacturing records generated, under the Dianthus Option Agreement and License Agreement (collectively the “Dianthus Agreements”) to Tenacia, for the exclusive right to research, develop, manufacture and commercialize products within China, Hong Kong, Macau and Taiwan (“greater China”). As a result of the Tenacia Agreement, the Company has no further obligations to Dianthus pursuant to the Dianthus Agreements.

Pursuant to the Tenacia Agreement, Tenacia paid the Company a one-time non-refundable upfront cash payment of $5.0 million, which was recognized as revenue in the fourth quarter of 2024. The Company is entitled to receive further development, regulatory and sales milestones from Tenacia of up to approximately $86.0 million if certain milestones are successfully achieved. The Company did not recognize revenue related to the Tenacia Agreement during the three months ended March 31, 2025 and 2024.

License Agreement with Zai Lab (Hong Kong) Limited

In January 2025, the Company entered into a license agreement (the “Zai License Agreement”), with Zai, under which the Company granted Zai an exclusive sublicense to develop, manufacture and commercialize ZB001 and related programs in greater China. Under the Zai Agreement, Zai will be responsible for conducting all research and development activities, manufacturing, regulatory and commercialization in greater China.

Pursuant to the Zai Agreement, Zai paid the Company a one-time non-refundable upfront cash payment of $10.0 million. The Company is entitled to receive further development, regulatory and sales milestones from Zai up to approximately $117.0 million if certain milestones are successfully achieved, with passthrough obligations of $21.0 million due to Viridian. The Company is also eligible to receive tiered royalties on net sales in greater China, ranging from the low to mid-single digits, net of passthrough obligations due to Viridian.

The Company evaluated the terms of the Zai Agreement and determined it is within the scope of ASC 606. The Company identified the following promises in the Zai Agreement that were evaluated under the scope of ASC 606: (i) transfer of the license for ZB001, (ii) licensed technology transfer (iii) licensed material transfer and (iv) continued licensed technology transfer. The Company also evaluated whether certain options outlined in the Zai Agreement represented material rights that would give rise to a performance obligation and concluded that none of the options conveyed a material right to Zai or were immaterial and, therefore, are not considered separate performance obligations within the Zai Agreement.

The Company assessed the above promises and determined that the license for ZB001 and technology transfer are a combined distinct performance obligation within the scope of ASC 606. The licensed material transfer and the continued technology know-how transfer services are promises that are separately identifiable and considered to be distinct. The Company determined the transfer of the licensed materials and continued technology know-how transfer services were immaterial in the context of the contract based on the minimal resources required to fulfill the obligations and the estimated standalone selling price of the licensed materials. Therefore, the sublicense and technology transfer represent a single performance obligation at contract inception.

The Company concluded that the transaction price of $10.0 million was allocated to the combined performance obligation, which was recognized upon delivery prior to March 31, 2025. The Company used the most likely amount method to estimate variable consideration and estimated that the most likely amount for each potential developmental and regulatory variable consideration milestone payment under the agreement is zero, as achievement of those milestones is uncertain and susceptible to factors outside the Company’s control. Accordingly, all such milestone payments were excluded from the transaction price. Management will reevaluate the transaction price at the end of each reporting period and as uncertain events are resolved or other changes in circumstances occur, will adjust the transaction price as necessary. Sales and royalty based milestones structured on the level of sales, were also excluded from the transaction price, as the license is deemed to be the predominant item to which the transaction price relates. The Company will recognize such milestone and

royalty revenue at the later of (i) when the related sales occur, or (ii) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

As of March 31, 2025, no milestones were achieved or deemed probable of achievement.

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2025	Apr. 30, 2025
Document and Entity Information [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2025
Document Transition Report	false
Entity File Number	001-42270
Entity Registrant Name	Zenas BioPharma, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	93-2749244
Entity Address, Address Line One	852 Winter Street
Entity Address, Adress Line Two	Suite 250
Entity Address, City or Town	Waltham
Entity Address State Or Province	MA
Entity Address, Postal Zip Code	02451
City Area Code	857
Local Phone Number	271-2954
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
Title of 12(b) Security	Common stock, par value $0.0001 per share
Trading Symbol	ZBIO
Security Exchange Name	NASDAQ
Entity Common Stock, Shares Outstanding		41,834,182
Entity Central Index Key	0001953926
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q1
Amendment Flag	false

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Current assets:
Cash and cash equivalents	$ 196,554	$ 319,742
Short-term investments	115,825	31,024
Restricted cash		90
Prepaid expenses and other current assets	5,428	5,067
Total current assets	317,807	355,923
Property and equipment, net	72	185
Operating lease right-of-use assets, net	1,204	1,004
Long-term investments	1,835
Other non-current assets	12,848	12,856
Total assets	333,766	369,968
Current liabilities:
Accounts payable	20,018	17,136
Accrued expenses	28,206	39,371
Operating lease liabilities, current	908	785
Total current liabilities	49,132	57,292
Operating lease liabilities, non-current	317	218
Total liabilities	49,449	57,510
Commitments and contingencies (Note 12)
Stockholders' equity:
Preferred stock, par value $0.0001 per share; 25,000,000 shares authorized and no shares issued and outstanding as of March 31, 2025 and December 31, 2024
Common stock, par value $0.0001 per share; 175,000,000 shares authorized; 41,821,887 and 41,793,412 shares issued and outstanding as of March 31, 2025 and December 31, 2024, respectively	4	4
Additional paid-in capital	705,136	699,651
Accumulated other comprehensive income	141	194
Accumulated deficit	(420,964)	(387,391)
Total stockholders' equity	284,317	312,458
Total liabilities and stockholders' equity	$ 333,766	$ 369,968

Stock-Based Compensation - Stock Options (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2025 USD ($) $ / shares shares
Number of Shares
Balance outstanding at beginning of year (in shares) \| shares	8,706,197
Granted (in shares) \| shares	108,000
Exercised (in shares) \| shares	(28,475)
Forfeited or cancelled (in shares) \| shares	(115,153)
Balance outstanding at end of year (in shares) \| shares	8,670,569
Options vested and exercisable at end of year (in shares) \| shares	1,434,494
Options vested and expected to vest end of year (in shares) \| shares	8,670,569
Weighted - Average Exercise Price
Balance outstanding at beginning of year (in dollars per share) \| $ / shares	$ 13.21
Granted (in dollars per share) \| $ / shares	7.28
Exercised (in dollars per share) \| $ / shares	3.48
Forfeited or cancelled (in dollars per share) \| $ / shares	13.94
Balance outstanding at end of year (in dollars per share) \| $ / shares	13.16
Options vested and exercisable at end of year (in dollars per share) \| $ / shares	7.93
Options vested and expected to vest at end of year (in dollars per share) \| $ / shares	$ 13.16
Weighted-Average Remaining Contractual Term (In years)
Balance outstanding at end of year (in years)	8 years 6 months 10 days
Options vested and exercisable at end of year (in years)	5 years 7 months 13 days
Options vested and expected to vest at end of year (in years)	8 years 6 months 10 days
Aggregate Intrinsic Value
Balance at beginning of year \| $	$ 2,104
Exercised \| $	136
Balance outstanding at end of year \| $	1,877
Options vested and exercisable at end of year \| $	1,708
Options vested and expected to vest at end of year \| $	1,877
Employee Stock Option
Aggregate Intrinsic Value
Unrecognized compensation cost related to unvested stock options \| $	$ 68,400
Weighted average period over which unrecognized compensation cost is expected to be recognized	3 years 1 month 24 days

Leases

3 Months Ended

Mar. 31, 2025

Leases

Leases

6.Leases

The Company has various leases for office space, which are accounted for as operating leases and generally have terms of less than two years in length, some of which have the option to renew. The Company recognizes monthly operating lease expense on a straight-line basis over the term of the lease as general and administrative expenses in the condensed consolidated statements of operations and comprehensive loss. Variable lease expense relates primarily to office lease common area maintenance, insurance, and property taxes, and it is expensed as incurred. Variable lease expense is also excluded from the calculation of lease liabilities and right-of-use-assets.

The minimum lease payments under the Company’s operating leases are expected to be as follows (in thousands):


Fiscal Year	Amount
2025 (remaining nine months)	$	713
2026		453
2027		136
Thereafter		—
Total future minimum lease payments		1,302
Less: imputed interest		(77)
Total operating lease liabilities	$	1,225

Other Assets (Tables)

3 Months Ended

Mar. 31, 2025

Other Assets

Summary of other assets

Other assets consisted of the following (in thousands):


	March 31, 2025		December 31, 2024
Clinical trial deposits	$	12,639	$	12,639
Other		209		217
Total other assets	$	12,848	$	12,856

Common Stock - Reserved for Issuance (Details) - shares	Mar. 31, 2025	Dec. 31, 2024
Common Stock
Options to purchase common stock	8,670,569	8,706,197
Remaining shares reserved for future issuance	2,456,222	359,399
Employee stock purchase plan	815,890	397,956
Total	11,942,681	9,463,552

Fair Value Measurements

3 Months Ended

Mar. 31, 2025

Fair Value Measurements

Fair Value Measurements

3.Fair Value Measurements


		As of March 31, 2025
Description		Total Carrying Value		Quoted Prices in Active Market (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Observable Inputs (Level 3)
Assets:
Cash	$	23,721	$	23,721	$	—	$	—
Money market funds		172,833		172,833		—		—
Short-term investments:
Commercial paper		6,387		—		6,387		—
Corporate debt securities		45,418		—		45,418		—
Government securities		64,020		64,020		—		—
Long-term investments:
Corporate debt securities		1,835		—		1,835		—
Total assets	$	314,214	$	260,574	$	53,640	$	—


		As of December 31, 2024
Description		Total Carrying Value		Quoted Prices in Active Market (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Other Observable Inputs (Level 3)
Assets:
Cash	$	19,070	$	19,070	$	—	$	—
Money market funds		300,672		300,672		—		—
Short-term investments:
Commercial paper		3,315		—		3,315		—
Corporate debt securities		8,601		—		8,601		—
Government securities		19,108		19,108		—		—
Total assets	$	350,766	$	338,850	$	11,916	$	—

There have been no material impairments of our assets measured and carried at fair value as of March 31, 2025 and December 31, 2024. In addition, there have been no changes in valuation techniques as of March 31, 2025 and December 31, 2024. The fair value of Level 1 instruments classified as money market funds and government securities are valued using quoted market prices in active markets. The fair value of Level 2 instruments classified as short-term investments was determined using other than quoted prices in active markets, which are either directly or indirectly observable as of the reporting date and fair value is determined using models or other valuation methodologies. During the three months ended March 31, 2025 and year ended December 31, 2024, there were no transfers between levels.

The short and long-term investments are classified as available-for-sales securities. As of March 31, 2025, the remaining contractual maturities of the available-for-sales securities were 1 to 18 months, the balance in the Company’s accumulated other comprehensive income was comprised of activity related to the Company’s available-for-sale securities. There were no realized gains or losses recognized on the sale or maturity of available-for-sale securities during the three months ended March 31, 2025 and 2024. As a result, the Company did not reclassify any amounts out of accumulated other comprehensive income for the same period. The Company had a limited number of available-for-sale securities in

insignificant loss positions as of March 31, 2025, which the Company does not intend to sell and has concluded will not be required to sell before recovery of amortized cost for the investment maturity.

The following table summarizes the available-for-sale securities (in thousands):


	As of March 31, 2025
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
March 31, 2025
Commercial paper	$	6,378	$	9	$	—	$	6,387
Corporate debt securities		47,228		29		(4)		47,253
Government securities		64,011		13		(4)		64,020
Total	$	117,617	$	51	$	(8)	$	117,660


	As of December 31, 2024
		Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
December 31, 2024
Commercial paper	$	3,311	$	4	$	—	$	3,315
Corporate debt securities		8,589		12		—		8,601
Government securities		19,093		17		(2)		19,108
Total	$	30,993	$	33	$	(2)	$	31,024

Certain short-term debt securities with original maturities of less than 90 days are included in cash and cash equivalents on the condensed consolidated balance sheets and are not included in the table above.

- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Common Stock

3 Months Ended

Mar. 31, 2025

Common Stock

Common Stock

9.Common Stock

In September 2024, upon the completion of the IPO, the Company restated its certificate of incorporation, pursuant to which the Company is authorized to issue 175,000,000 shares of $0.0001 par value common stock. The voting, dividend and liquidation rights of the holders of the Company’s common stock were subject to and qualified by the rights, powers and preference of the holders of any preferred stock then issued and outstanding.

The holders of the common stock are entitled to one vote for each share of common stock held at all meetings of stockholders (and written actions in lieu of meetings), and there are no cumulative voting rights.

The Company had reserved the following shares of common stock for the potential conversion of outstanding stock options:


	March 31, 2025	December 31, 2024
Options to purchase common stock	8,670,569	8,706,197
Remaining shares reserved for future issuance	2,456,222	359,399
Employee stock purchase plan	815,890	397,956
Total	11,942,681	9,463,552

- Definition

The entire disclosure for equity.

+ References

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

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

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

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478448/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480237/815-40-50-6

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1

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

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

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-13

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

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

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-14

Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 16
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-16

Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

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

Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481112/505-10-50-18

+ Details

License and Collaboration Revenue (Details) - USD ($) $ in Thousands	1 Months Ended			3 Months Ended
	Jan. 31, 2025	Oct. 31, 2024	Aug. 31, 2023	Mar. 31, 2025	Mar. 31, 2024
Nature of Business
Revenue				$ 10,000
BMS Agreement
Nature of Business
Amount of upfront cash payment received			$ 50,000
Maximum amount of payments receivable			79,500
Amount of reduction to research and development expenses				1,700	$ 1,000
Amount receivable				$ 1,700	$ 1,000
Sales milestone payments receivable			$ 70,000
Novation Agreement
Nature of Business
Amount of upfront cash payment received		$ 5,000
Maximum amount of payments receivable		$ 86,000
License Agreement with Zai Lab (Hong Kong) Limited
Nature of Business
Amount of upfront cash payment received	$ 10,000
Maximum amount of payments receivable	117,000
Agreement transaction price	10,000
Viridian Agreement
Nature of Business
Development milestone expense payable	$ 21,000

Nature of Business

3 Months Ended

Mar. 31, 2025

Nature of Business

Nature of Business

1.Nature of Business

Organization

Zenas BioPharma, Inc. (“Zenas” or the “Company”) was incorporated in November 2019 as Zenas BioPharma (Cayman) Limited, an exempted company incorporated in the Cayman Islands with limited liability and commenced operations in 2020. On August 2, 2023, the Company (then known as Zenas BioPharma (Cayman) Limited) de-registered from the Cayman Islands and registered by way of continuation in the State of Delaware. Zenas is a clinical-stage global biopharmaceutical company committed to being a leader in the development and commercialization of transformative immunology-based therapies for patients in need. The Company’s goal is to build an immunology and inflammation (“I&I”) focused biopharmaceutical company. The Company has in-licensed and is developing several product candidates for the treatment of various auto-immune and rare diseases. The Company is headquartered in Waltham, Massachusetts and operates in one segment, which is the business of acquiring and developing immune-based therapies for potential commercialization.

The Company’s condensed consolidated financial statements include the accounts of its wholly owned subsidiaries which include Zenas BioPharma (HK) Limited (“Zenas HK”), Zenas BioPharma (USA) LLC, Shanghai Zenas Biotechnology Co. Limited, Zenas BioPharma Securities Corp., and Zenas BioPharma GmbH.

Liquidity and Capital Resources

Since its inception, the Company has devoted its efforts principally to research and development, and raising capital. The Company is subject to risks and uncertainties common to clinical stage companies in the biopharmaceutical industry, including, but not limited to, completing preclinical studies and clinical trials, obtaining regulatory approval for product candidates, market acceptance of products, development by competitors of new technological innovations, dependence on key personnel, the ability to attract and retain qualified employees, reliance on third-party organizations, protection of proprietary technology, compliance with government regulations, and the ability to raise additional capital to fund operations. The Company’s revenues to date have been generated from payments received under the Company’s license and collaboration agreement with Bristol-Myers Squibb Company (“BMS”), novation agreement with Tenacia Biotechnology (Hong Kong) Co., Limited (“Tenacia”) and license agreement with Zai Lab (Hong Kong) Limited (“Zai”) (please see Note 7, License and Collaboration Revenue, to these condensed consolidated financial statements). The Company has not generated any revenue from product sales since inception, and its product candidates currently under development will require significant additional research and development efforts, including extensive clinical testing and regulatory approval prior to commercialization.

On September 16, 2024, the Company completed its initial public offering (“IPO”), in which the Company issued and sold 15,220,588 shares of its common stock, including 1,985,294 shares pursuant to the full exercise of the underwriters’ option to purchase additional shares, at a public offering price of $17.00 per share, for aggregate gross proceeds of $258.7 million. The Company received $234.3 million in net proceeds after deducting underwriting discounts, commissions and other offering expenses. In connection with the IPO, all outstanding shares of convertible preferred stock converted into 24,978,715 shares of the Company’s common stock.

In connection with, and prior to, the Company’s IPO, the Company effected a 1-for-8.6831 reverse stock split of the Company’s issued and outstanding common stock and adjusted the conversion ratio of all the Company’s outstanding convertible preferred stock. Accordingly, all share and per share amounts for all periods presented in the accompanying condensed consolidated financial statements and notes thereto have been retroactively adjusted, where applicable, to reflect the reverse stock split and the adjustment of the preferred stock conversion ratios.

The Company has incurred operating losses and negative cash flows, since its inception, including net losses of $33.6 million and $27.8 million for the three months ended March 31, 2025 and 2024, respectively. As of March 31, 2025, the

Company had an accumulated deficit of $421.0 million. Management expects operating losses and negative operating cash flows to continue for the foreseeable future.

The Company expects that its existing cash, cash equivalents and investments of $314.2 million as of March 31, 2025 will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the date this Form 10-Q is filed. The Company will need additional financing to support its continuing operations and to pursue its growth strategy. Until such time as the Company can generate significant revenue from product sales, if ever, it expects to finance its operations through a combination of private or public equity financings, debt financings or other capital sources, including collaborations with other companies or other strategic transactions and licensing agreements. The Company may be unable to raise additional funds or enter into such other agreements when needed on favorable terms or at all. The inability to raise capital as and when needed could have a negative impact on the Company’s financial condition and its ability to pursue its business strategy. The Company will need to generate significant revenue to achieve profitability, and it may never do so.

Segment Information (Tables)

3 Months Ended

Mar. 31, 2025

Segment Information

Schedule of financial data for reportable segments

The following table presents certain financial data for the Company’s reportable segments for the three months ended March 31, 2025 and 2024 (in thousands):


		March 31,
		2025		2024
Revenue	$	10,000	$	-
Less:
Direct research and development expenses:¹
Obexelimab		23,491		12,295
Other programs (ZB002 & ZB004)		203		894
Partnered regional programs (ZB001 & ZB005)		99		1,588
Unallocated research and development²		9,541		7,457
General and administrative³		8,610		4,397
Stock-based compensation		5,386		947
Other segment items⁴		(3,757)		222
Segment net loss	$	(33,573)	$	(27,800)

³General and administrative expenses primarily consist of professional fees, depreciation expense, facilities expenses as well as all other personnel costs, excluding stock-based compensation.

Related Party Transactions

3 Months Ended

Mar. 31, 2025

Related Party Transactions

Related Party Transactions

13.Related Party Transactions

Xencor, Inc.

The Company has obtained exclusive, worldwide licenses from Xencor to research, develop, manufacture, market and sell three antibody product candidates pursuant to two license agreements. The Company has concluded that Xencor is a related party, due to the issuance of convertible preferred stock in December 2020 and April 2023. In connection with the completion of the IPO, in September 2024, all outstanding shares of preferred stock converted into shares of common stock. As of March 31, 2025, Xencor held less than 10% of shares of the Company’s outstanding common stock.

Viridian Therapeutics, Inc.

The Company has obtained a license from Viridian to research, develop, manufacture, market and sell an antibody product candidate in China. The Company has concluded that Viridian is a related party because although Fairmount Funds Management LLC owns less than 10% of shares of the Company’s outstanding common stock, they have a seat on the Board and are also a 10% or greater stockholder of Viridian and have two seats on Viridian’s board of directors. As initial consideration for this license, the Company issued 38,707 shares of its common stock to Viridian during the year ended December 31, 2020. As of March 31, 2025, Viridian held 0.1% of shares of the Company’s outstanding common stock.

Zai Lab (Hong Kong) Limited

The Company has granted a sublicense to Zai to develop, manufacture and commercialize ZB001 and related programs in greater China. The Company has concluded that Zai is a related party, as the Company’s CEO and Chairman is a member of Zai’s board of directors.

For additional information on these arrangements, please see Note 7, License and Collaboration Revenue and Note 8, License Agreements, to these condensed consolidated financial statements.

- 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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-2

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-5

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480990/946-20-50-6

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477968/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(e))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479134/946-220-S99-1

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org/850/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-6

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 850
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483326/850-10-50-1

+ Details

Other Assets

3 Months Ended

Mar. 31, 2025

Other Assets

Other Assets

4.Other Assets

Other assets consisted of the following (in thousands):


	March 31, 2025		December 31, 2024
Clinical trial deposits	$	12,639	$	12,639
Other		209		217
Total other assets	$	12,848	$	12,856

Leases (Details)	Mar. 31, 2025
Maximum
Leases
Lease term	2 years

Common Stock (Details)	Mar. 31, 2025 Vote $ / shares shares	Dec. 31, 2024 $ / shares shares	Sep. 30, 2024 $ / shares shares
Common Stock
Common stock, shares authorized (in shares) \| shares	175,000,000	175,000,000	175,000,000
Common stock, par value (in dollar per share) \| $ / shares	$ 0.0001	$ 0.0001	$ 0.0001
Number of votes per share \| Vote	1