SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13D

Under the Securities Exchange Act of 1934

(Amendment No. 1)

Zenas BioPharma, Inc.

(Name of Issuer)

Common Stock, $0.0001 par value per share

(Title of Class of Securities)

98937L105

(CUSIP Number)

Leon O. Moulder, Jr.
c/o Zenas BioPharma, Inc., 852 Winter Street, Suite 250
Waltham, MA, 02451
857-271-2954

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

03/31/2026

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. Checkbox not checked

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

SCHEDULE 13D

CUSIP Number(s):

98937L105

Name of reporting person

Leon O. Moulder, Jr.

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 1,266,954.00
8	Shared Voting Power 1,762,967.00
9	Sole Dispositive Power 1,266,954.00
10	Shared Dispositive Power 1,762,967.00

Aggregate amount beneficially owned by each reporting person

3,029,921.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

4.794 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person:

(1) Rows 7 & 9: Consists of (i) 423,155 shares of common stock held directly by Mr. Moulder, and (ii) 843,799 shares of common stock underlying outstanding stock options exercisable within 60 days of the date of March 31, 2026. (2) Rows 8 & 10: Consists of (i) 1,726,039 shares of common stock held by Tellus BioVentures, LLC ("Tellus") and (ii) 36,928 shares of common stock held by Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008 (the "Trust"). Mr. Moulder is the Managing Member of Tellus and may be deemed to have sole voting and dispositive power over the shares held by Tellus, and Mr. Moulder is a trustee of the Trust and may be deemed to have sole voting and dispositive power of the shares held by the Trust. (3) Row 11: Consists of (i) 423,155 shares of common stock held directly by Mr. Moulder, (ii) 843,799 shares of common stock underlying outstanding stock options exercisable within 60 days of March 31, 2026, (iii) 1,726,039 shares of common stock held by Tellus and (iv) 36,928 shares of common stock held by the Trust. Mr. Moulder is the Managing Member of Tellus and may be deemed to have sole voting and dispositive power over the shares held by Tellus, and Mr. Moulder is a trustee of the Trust and may be deemed to have sole voting and dispositive power of the shares held by the Trust. (4) Row 13: Calculated based on 57,361,260 shares of Common Stock outstanding, as reported by the Issuer in its Annual Report on Form 10-K for the year ended December 31, 2025, as filed with the Securities and Exchange Commission (the "Commission") on March 16, 2026 (the "2025 10-K"), plus (i) 5,000,000 shares of common stock issued by the Issuer in a registered public offering on March 31, 2026 (the "Equity Offering Shares"), as reported by the Issuer in its Current Report on Form 8-K filed with the Commission on March 31, 2026 and (ii) the 843,799 shares of common stock issuable upon the exercise of the options held by Mr. Moulder that are exercisable within 60 days of March 31, 2026.

SCHEDULE 13D

CUSIP Number(s):

98937L105

Name of reporting person

Tellus BioVentures, LLC

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 1,726,039.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 1,726,039.00

Aggregate amount beneficially owned by each reporting person

1,726,039.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

2.77 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person:

(1) Rows 8, 10 & 11: Consists of 1,726,039 shares of common stock held of record by Tellus. Mr. Moulder is the Managing Member of Tellus and may be deemed to have sole voting and dispositive power over the shares held by Tellus. (2) Row 13: Calculated based on 57,361,260 shares of Common Stock outstanding, as reported by the Issuer in the 2025 10-K, plus the Equity Offering Shares.

SCHEDULE 13D

CUSIP Number(s):

98937L105

Name of reporting person

Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008

Check the appropriate box if a member of a Group (See Instructions)

(a)

(b)

SEC use only

Source of funds (See Instructions)

Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)

Checkbox not checked

Citizenship or place of organization

FLORIDA

Number of Shares Beneficially Owned by Each Reporting Person With:

7	Sole Voting Power 0.00
8	Shared Voting Power 36,928.00
9	Sole Dispositive Power 0.00
10	Shared Dispositive Power 36,928.00

Aggregate amount beneficially owned by each reporting person

36,928.00

Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)

Checkbox not checked

Percent of class represented by amount in Row (11)

0.06 %

Type of Reporting Person (See Instructions)

Comment for Type of Reporting Person:

(1) Rows 8, 10 & 11: Consists of 36,928 shares of common stock held of record by Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008 (the "Trust"). Mr. Moulder is a Trustee of the Trust and may be deemed to have sole voting and dispositive power over the shares held by the Trust. (2) Row 13: Calculated based on 57,361,260 shares of Common Stock outstanding, as reported by the Issuer in the 2025 10-K, plus the Equity Offering Shares.

SCHEDULE 13D

Item 1.

Security and Issuer

(a)

Title of Class of Securities:

Common Stock, $0.0001 par value 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. 1 (this "Amendment") amends and supplements the Schedule 13D initially filed by Mr. Moulder, Tellus and the Trust on January 14, 2026 (the "Original Schedule 13D"). Only those items that are hereby reported are amended; all other items reported in the Original Schedule 13D remain unchanged. Information given in response to each item shall be deemed incorporated by reference in all other items, as applicable. Capitalized terms not defined in this Amendment have the meanings ascribed to them in the Original Schedule 13D. This Amendment is filed with respect to the Common Stock, par value $0.0001 per share ("Common Stock"), of Zenas BioPharma, Inc., a Delaware corporation (the "Issuer"). The address of the principal executive offices of the Issuer is 852 Winter Street, Suite 250, Waltham, MA 02451.

Item 3.

Source and Amount of Funds or Other Consideration

Item 3 of the Original Schedule 13D is hereby amended and supplemented by adding the following to the end of Item 3: On February 2, 2026, Mr. Moulder purchased 57,000 shares of Common Stock in multiple open-market transactions at prices per share ranging from $17.69 to $18.14, inclusive. Between March 30, 2026 and March 31, 2026, Tellus purchased 54,000 shares of Common Stock in multiple open-market transactions at prices per share ranging from $18.195 to $19.58, inclusive.

Item 5.

Interest in Securities of the Issuer

(a)

See Items 7-11 of the cover pages of this Statement.

(b)

See Items 7-11 of the cover pages of this Statement.

(c)

Except as reported in this Statement, no Reporting Person has effected any transactions in the Issuer's securities within the past 60 days.

(d)

Not applicable.

(e)

March 31, 2026

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.

Leon O. Moulder, Jr.

Signature:	/s/ Leon O. Moulder, Jr.
Name/Title:	Leon O. Moulder, Jr.
Date:	04/02/2026

Tellus BioVentures, LLC

Signature:	/s / Leon O. Moulder, Jr.
Name/Title:	Leon O. Moulder, Jr., Managing Member
Date:	04/02/2026

Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008

Signature:	/s / Leon O. Moulder, Jr.
Name/Title:	Leon O. Moulder, Jr., Trustee
Date:	04/02/2026

Amendment: SEC Form SCHEDULE 13D/A filed by Zenas BioPharma Inc.