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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549 |
SCHEDULE 13D
Under the Securities Exchange Act of 1934
(Amendment No. 2)*
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Zenas BioPharma, Inc. (Name of Issuer) |
Common stock, par value $0.0001 per share (Title of Class of Securities) |
(CUSIP Number) |
Sasha Keough c/o SR One Capital Management, LP, 929 Main Street, Suite 200 Redwood City, CA, 94063 (410) 800-7503 (Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications) |
08/13/2026 (Date of Event Which Requires Filing of This Statement) |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital Management, LLC | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
5,037,854.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
7.7 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
OO |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital Fund II Aggregator, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
WC | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,946,564.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
3.0 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital Partners II, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,946,564.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
3.0 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
AMZL, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
WC | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,917,895.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital SMA Partners, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,917,895.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
2.9 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital Opportunities Fund I, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
WC | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,173,395.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.8 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
|
| CUSIP No. |
| 1 |
Name of reporting person
SR One Capital Opportunities Partners I, LP | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
DELAWARE
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
1,173,395.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
1.8 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
PN |
SCHEDULE 13D
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| CUSIP No. |
| 1 |
Name of reporting person
Simeon George | ||||||||
| 2 | Check the appropriate box if a member of a Group (See Instructions)
(a)
(b) | ||||||||
| 3 | SEC use only | ||||||||
| 4 |
Source of funds (See Instructions)
AF | ||||||||
| 5 |
Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)
| ||||||||
| 6 | Citizenship or place of organization
UNITED STATES
| ||||||||
| Number of Shares Beneficially Owned by Each Reporting Person With: |
| ||||||||
| 11 | Aggregate amount beneficially owned by each reporting person
5,037,854.00 | ||||||||
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)
| ||||||||
| 13 | Percent of class represented by amount in Row (11)
7.7 % | ||||||||
| 14 | Type of Reporting Person (See Instructions)
IN |
SCHEDULE 13D
|
| Item 1. | Security and Issuer | |
| (a) | Title of Class of Securities:
Common stock, par value $0.0001 per share | |
| (b) | Name of Issuer:
Zenas BioPharma, Inc. | |
| (c) | Address of Issuer's Principal Executive Offices:
852 Winter Street, Suite 250, Waltham,
MASSACHUSETTS
, 02451. | |
Item 1 Comment:
This Amendment No. 2 ("Amendment No. 2") to Schedule 13D amends and supplements the statement on Schedule 13D originally filed on September 23, 2024 (the "Schedule 13D") and Amendment No. 1 thereto filed on October 14, 2025 ("Amendment No. 1") relating to the Common Stock of the Issuer.
Certain terms used but not defined in this Amendment No. 2 have the meanings assigned thereto in the Schedule 13D (and Amendment No. 1 thereto). Except as specifically provided herein, this Amendment No. 2 does not modify any of the information previously reported on the Schedule 13D (and Amendment No. 1 thereto).
This Amendment No. 2 is being filed to report that the beneficial ownership of Common Stock by the Reporting Persons (as defined below) has decreased by more than 1% as a result of an increase in the number of Common Stock outstanding. | ||
| Item 2. | Identity and Background | |
| (a) | SR One Capital Management, LLC ("SR One Capital Management"); SR One Capital Fund II Aggregator, LP ("SR One Fund II Aggregator"); SR One Capital Partners II, LP ("SR One Partners II"); AMZL, LP ("AMZL"); SR One Capital SMA Partners, LP ("SMA Partners"); SR One Capital Opportunities Fund I, LP ("SR One Opportunities Fund I"); SR One Capital Opportunities Partners I, LP ("SR One Opportunities Partners I"); and Simeon George, M.D. ("Dr. George").
SR One Fund II Aggregator is directly controlled by its general partner, SR One Partners II. AMZL is directly controlled by its general partner, SMA Partners. SR One Opportunities Fund I is directly controlled by its general partner, SR One Opportunities Partners I. SR One Partners II, SMA Partners and SR One Opportunities Partners I are directly controlled by their general partners, SR One Capital Management, and Dr. George controls SR One Capital Management. Accordingly, each of SR One Capital Management and Dr. George may be deemed to have voting and dispositive power with respect to the SR One Fund II Aggregator Shares, the AMZL Shares and the SR One Opportunities Fund I Shares (each as defined below).
The persons named in this Item 2 are referred to individually herein as a "Reporting Person" and collectively as the "Reporting Persons." SR One Fund II Aggregator, AMZL and SR One Opportunities Fund I are referred to collectively as the "Funds." | |
| (b) | The address of each Reporting Person for purposes of this filing is c/o SR One Capital Management, LP, 929 Main Street, Suite 200, Redwood City, CA 94063. | |
| (c) | The principal business of the Funds is to invest in and assist growth-oriented businesses. The principal business of SR One Partners II is to act as the sole general partner of SR One Fund II Aggregator. The principal business of SMA Partners is to act as the sole general partner of AMZL. The principal business of SR One Opportunities Partners I is to act as the sole general partner of SR One Opportunities Fund I. The principal business of SR One Capital Management is to act as the sole general partner of SR One Partners II, SMA Partners, SR One Opportunities Partners I and a number of affiliated partnerships with similar businesses. The principal business of Dr. George is to manage SR One Capital Management. | |
| (d) | During the five years prior to the date hereof, none of the Reporting Persons has been convicted in a criminal proceeding or has been a party to a civil proceeding ending in a judgment, decree or final order enjoining future violations of, or prohibiting activities subject to, federal or state securities laws or finding any violation with respect to such laws. | |
| (e) | During the five years prior to the date hereof, none of the Reporting Persons has been convicted in a criminal proceeding or has been a party to a civil proceeding ending in a judgment, decree or final order enjoining future violations of, or prohibiting activities subject to, federal or state securities laws or finding any violation with respect to such laws. | |
| (f) | SR One Fund II Aggregator, SR One Partners II, AMZL, SMA Partners, SR One Opportunities Fund I, and SR One Opportunities Partners I are limited partnerships organized under the laws of the State of Delaware. SR One Capital Management is a limited liability company organized under the laws of the State of Delaware. Dr. George is a United States citizen. | |
| Item 3. | Source and Amount of Funds or Other Consideration | |
Not applicable. | ||
| Item 4. | Purpose of Transaction | |
Not applicable. | ||
| Item 5. | Interest in Securities of the Issuer | |
| (a) | The percentage of outstanding shares of Common Stock which may be deemed to be beneficially owned by each Reporting Person is set forth on Line 13 of such Reporting Person's cover sheet. Such percentage was calculated based on 65,176,723 shares of Common Stock reported by the Issuer to be outstanding as of July 31, 2026, on the Issuer's Form 10-Q filed with the Securities Exchange Commission on August 13, 2026. | |
| (b) | Regarding the number of shares as to which such person has:
(i) sole power to vote or to direct the vote: See line 7 of cover sheets
(ii) shared power to vote or to direct the vote: See line 8 of cover sheets
(iii) sole power to dispose or to direct the disposition: See line 9 of cover sheets
(iv) shared power to dispose or to direct the disposition: See line 10 of cover sheets | |
| (c) | None of the Reporting Persons has effected any transaction in shares of Common Stock during the last 60 days. | |
| (d) | No other person is known to have the right to receive or the power to direct the receipt of dividends from, or any proceeds from the sale of, Common Stock beneficially owned by any of the Reporting Persons. | |
| (e) | Not applicable. | |
| Item 6. | Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer | |
Not applicable. | ||
| Item 7. | Material to be Filed as Exhibits. | |
Exhibit 1 - Agreement regarding filing of joint Schedule 13D.
Exhibit 2 - Power of Attorney regarding filings under the Securities Exchange Act of 1934, as amended. | ||
| SIGNATURE | |
After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
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Comments accompanying signature:
This Amendment No. 2 to Schedule 13D was executed by Sasha Keough on behalf of the individuals listed above pursuant to a Power of Attorney, a copy of which is attached as Exhibit 2. |