# EDGAR Filing Document

**Accession Number:** 0001953926
**File Stem:** 0001104659-26-039279
**Filing Date:** 2026-4
**Character Count:** 13344
**Document Hash:** 339e228bb051382821a45c09cabb7cf4
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001104659-26-039279.hdr.sgml**: 20260402

**ACCESSION NUMBER**: 0001104659-26-039279

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D/A

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260402

**DATE AS OF CHANGE**: 20260402

**SUBJECT COMPANY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Zenas BioPharma, Inc.
- **CENTRAL INDEX KEY:** 0001953926
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-94625
- **FILM NUMBER:** 26835720

**BUSINESS ADDRESS:**
- **STREET 1:** 852 WINTER STREET, SUITE 250
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451
- **BUSINESS PHONE:** 857-271-2954

**MAIL ADDRESS:**
- **STREET 1:** 852 WINTER STREET, SUITE 250
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Zenas BioPharma (Cayman) Ltd
- **DATE OF NAME CHANGE:** 20221108
**FILED BY**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** MOULDER LEON O JR
- **CENTRAL INDEX KEY:** 0001228865

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D/A

**MAIL ADDRESS:**
- **STREET 1:** C/O TESARO, INC.
- **STREET 2:** 1000 WINTER STREET, SUITE 3300
- **CITY:** WALTHAM
- **STATE:** MA
- **ZIP:** 02451

### UNITED STATES 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)*

**—**

*(CUSIP Number)*

**Leon O. Moulder, Jr.**<br>c/o Zenas BioPharma, Inc.<br>852 Winter Street, Suite 250<br>Waltham MA 02451<br>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)*

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Leon O. Moulder, Jr.** | Name of reporting person<br>**Leon O. Moulder, Jr.** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**X1** | Citizenship or place of organization<br>**X1** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**1266954.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**1762967.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**1266954.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**1762967.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**3029921.00** | Aggregate amount beneficially owned by each reporting person<br>**3029921.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**4.794%** | Percent of class represented by amount in Row (11)<br>**4.794%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for 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.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Tellus BioVentures, LLC** | Name of reporting person<br>**Tellus BioVentures, LLC** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**WC** | Source of funds (See Instructions)<br>**WC** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**DELAWARE** | Citizenship or place of organization<br>**DELAWARE** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**1726039.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**1726039.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**1726039.00** | Aggregate amount beneficially owned by each reporting person<br>**1726039.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**2.77%** | Percent of class represented by amount in Row (11)<br>**2.77%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

**Comment for 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.

| **CUSIP No.** | **—** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008** | Name of reporting person<br>**Leon O. Moulder, Jr. Revocable Trust U/A dtd 9/9/2008** | |
| 2 | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | Check the appropriate box if a member of a Group (See Instructions)<br>[ ] (a)<br>[x] (b) | |
| 3 | SEC use only | SEC use only | |
| 4 | Source of funds (See Instructions)<br>**AF** | Source of funds (See Instructions)<br>**AF** | |
| 5 | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | Check if disclosure of legal proceedings is required pursuant to Items 2(d) or 2(e)<br>[ ] | |
| 6 | Citizenship or place of organization<br>**FLORIDA** | Citizenship or place of organization<br>**FLORIDA** | |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 7 | Sole Voting Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**36928.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**0.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**36928.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**36928.00** | Aggregate amount beneficially owned by each reporting person<br>**36928.00** | |
| 12 | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | Check if the aggregate amount in Row (11) excludes certain shares (See Instructions)<br>[ ] | |
| 13 | Percent of class represented by amount in Row (11)<br>**0.06%** | Percent of class represented by amount in Row (11)<br>**0.06%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**OO** | Type of Reporting Person (See Instructions)<br>**OO** | |

---

**Comment for 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.

**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, MA, 02451

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 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.

### 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.

**Reporting Person:** Leon O. Moulder, Jr.

**Signature:** /s/ Leon O. Moulder, Jr.

**Name/Title:** Leon O. Moulder, Jr.

**Date:** 04/02/2026

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.

**Reporting Person:** Tellus BioVentures, LLC

**Signature:** /s / Leon O. Moulder, Jr.

**Name/Title:** Leon O. Moulder, Jr., Managing Member

**Date:** 04/02/2026

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.

**Reporting Person:** 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