# EDGAR Filing Document

**Accession Number:** 0001134657
**File Stem:** 0001231919-26-000057
**Filing Date:** 2026-1
**Character Count:** 21565
**Document Hash:** e69bbbd9698f64f686840b581d6c8aae
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001231919-26-000057.hdr.sgml**: 20260114

**ACCESSION NUMBER**: 0001231919-26-000057

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260112

**FILED AS OF DATE**: 20260114

**DATE AS OF CHANGE**: 20260114

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** EVNIN LUKE
- **CENTRAL INDEX KEY:** 0001134657

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534231

**MAIL ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET
- **STREET 2:** SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM ONCOLOGY INNOVATIONS FUND LP
- **CENTRAL INDEX KEY:** 0001719960

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534226

**BUSINESS ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142

**FORMER NAME:**
- **FORMER CONFORMED NAME:** MPM ONCOLOGY INNOVATIONS FUND L.P.
- **DATE OF NAME CHANGE:** 20171017
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM BIOVENTURES 2018 (B), L.P.
- **CENTRAL INDEX KEY:** 0001729504

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534230

**BUSINESS ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142

**FORMER NAME:**
- **FORMER CONFORMED NAME:** MPM BIOVENTURES 2018 (B) LP
- **DATE OF NAME CHANGE:** 20180126
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM BIOVENTURES 2018, L.P.
- **CENTRAL INDEX KEY:** 0001729505

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534232

**BUSINESS ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM ASSET MANAGEMENT INVESTORS BV2018 LLC
- **CENTRAL INDEX KEY:** 0001734817

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534227

**BUSINESS ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** 450 KENDALL STREET
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM BioVentures 2018 GP LLC
- **CENTRAL INDEX KEY:** 0001818701

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534228

**BUSINESS ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET
- **STREET 2:** SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET
- **STREET 2:** SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM BioVentures 2018 LLC
- **CENTRAL INDEX KEY:** 0001818702

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534229

**BUSINESS ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET
- **STREET 2:** SUITE 1100
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
- **BUSINESS PHONE:** 617-425-920

**MAIL ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET
- **STREET 2:** SUITE 1100
- **CITY:** CAMBRIDGE
- **STATE:** MA
- **ZIP:** 02142
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** MPM Oncology Innovations Fund GP LLC
- **CENTRAL INDEX KEY:** 0001857903

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26534225

**BUSINESS ADDRESS:**
- **STREET 1:** C/O MPM BIOIMPACT
- **STREET 2:** 399 BOYLSTON STREET, SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 617-425-9200

**MAIL ADDRESS:**
- **STREET 1:** C/O MPM BIOIMPACT
- **STREET 2:** 399 BOYLSTON STREET, SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
**ISSUER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Aktis Oncology, Inc.
- **CENTRAL INDEX KEY:** 0002035832
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 852584233
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**BUSINESS ADDRESS:**
- **STREET 1:** 17 DRYDOCK AVENUE
- **STREET 2:** SUITE #17-401
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210
- **BUSINESS PHONE:** 978-237-4380

**MAIL ADDRESS:**
- **STREET 1:** 17 DRYDOCK AVENUE
- **STREET 2:** SUITE #17-401
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM BIOVENTURES 2018, L.P.<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>EVNIN LUKE<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM BIOVENTURES 2018 (B), L.P.<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM BioVentures 2018 LLC<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM BioVentures 2018 GP LLC<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM ASSET MANAGEMENT INVESTORS BV2018 LLC<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM ONCOLOGY INNOVATIONS FUND LP<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>MPM Oncology Innovations Fund GP LLC<br><sub>(Last) (First) (Middle)</sub><br>C/O MPM BIOIMPACT LLC<br>399 BOYLSTON STREET, SUITE 1100<br><sub>(Street)</sub><br>BOSTON, MA 02116<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2026-01-12 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director [X] 10% Owner<br>[ ] Officer (give title below) [ ] Other (specify below)<br>_ _ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[ ] Form filed by One Reporting Person<br>[X] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2026-01-12 |  | C |  | 1314262<sup>(1)</sup> | A | <sup>(2)</sup> | 1655971 | I | See Footnote<sup>(3)(4)</sup> |
| Common Stock | 2026-01-12 |  | C |  | 5914197<sup>(5)</sup> | A | <sup>(2)</sup> | 7570168 | I | See Footnote<sup>(3)(6)</sup> |
| Common Stock | 2026-01-12 |  | C |  | 1577119<sup>(7)</sup> | A | <sup>(2)</sup> | 9147287 | I | See Footnote<sup>(3)(8)</sup> |
| Common Stock | 2026-01-12 |  | P |  | 1112777<sup>(9)</sup> | A | $18 | 10260064 | I | See Footnote<sup>(3)(10)</sup> |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| Series Seed Redeemable Convertible Preferred Stock | <sup>(2)</sup> | 2026-01-12 |  | C |  |  | 5000000 | <sup>(2)</sup> | <sup>(2)</sup> | Common Stock | 1314262 | 0<sup>(2)</sup> | 0 | I | See Footnote<sup>(1)(3)</sup> |
| Series A Redeemable Convertible Preferred Stock | <sup>(2)</sup> | 2026-01-12 |  | C |  |  | 22500000 | <sup>(2)</sup> | <sup>(2)</sup> | Common Stock | 5914197 | 0<sup>(2)</sup> | 0 | I | See Footnote<sup>(3)(5)</sup> |
| Series B Redeemable Convertible Preferred Stock | <sup>(2)</sup> | 2026-01-12 |  | C |  |  | 6000000 | <sup>(2)</sup> | <sup>(2)</sup> | Common Stock | 1577119 | 0<sup>(2)</sup> | 0 | I | See Footnote<sup>(3)(7)</sup> |

---

### Footnotes:

(1) The shares of common stock were issued upon conversion as follows:  556,810 by MPM BioVentures 2018, L.P. ("BV 2018"), 29,593 by MPM BioVentures 2018 (B), L.P. ("BV 2018(B)"), 10,988 by MPM Asset Management Investors BV2018 LLC ("AM BV2018"), 119,478 by MPM Oncology Innovations
Fund, L.P. ("MPM Oncology") and 597,393 by Oncology Impact Private Investment Fund 2, L.P. ("MPM Oncology Impact"). MPM BioVentures 2018 GP LLC and MPM BioVentures 2018 LLC ("BV2018 LLC") are the direct and indirect general partners of BV 2018 and
BV 2018(B). BV 2018 LLC is the manager of AM BV2018. Drs. Evnin and Gadicke are managing directors of BV 2018 LLC and managers of MPM Oncology Innovations Fund GP LLC, which is the general partner of MPM Oncology. Dr. Gadicke is the managingmember of MPM Oncology Investments 2 LLC, which is the general partner of MPM Oncology Impact.

(2) Each share of Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock automatically converted into shares of the Issuer's Common Stock on a 3.8044-for-1 basis into the number of shares of Common Stock shown in Column 7 without payment of further consideration upon the closing of the initial public offering of the Issuer's Common Stock. The Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock had no expiration date.

(3) The Reporting Persons disclaim beneficial ownership of the securities except to the extent of his or its pecuniary interest therein.

(4) The shares are held as follows: 341,709 by MPM Asset Management LLC ("MPM AM"), 556,810 by BV 2018, 29,593 by BV 2018(B), 10,988 by AM BV2018, 119,478 by MPM Oncology and 597,393 by MPM Oncology Impact. Dr. Gadicke is the manager of MPM AM.

(5) The shares of common stock were issued upon conversion as follows:  2,505,648 by BV 2018, 133,170 by BV 2018(B), 49,452 by AM BV2018, 537,654 by MPM Oncology and 2,688,273 by MPM Oncology Impact.

(6) The shares are held as follows: 341,709 by MPM AM, 3,062,458 by BV 2018, 162,763 by BV 2018(B), 60,440 by AM BV2018, 657,132 by MPM Oncology and 3,285,666 by MPM Oncology Impact.

(7) The shares of common stock were issued upon conversion as follows:  668,173 by BV 2018, 35,512 by BV 2018(B), 13,187 by AM BV2018, 143,374 by MPM Oncology and 716,873 by MPM Oncology Impact.

(8) The shares are held as follows: 341,709 by MPM AM, 3,730,631 by BV 2018, 198,275 by BV 2018(B), 73,627 by AM BV2018, 800,506 by MPM Oncology and 4,002,539 by MPM Oncology Impact.

(9) The shares were purchased as follows: 219,897 by BV 2018, 8,689 by BV 2018(B), 4,284 by AM BV2018, 46,574 by MPM Oncology and 833,333 by MPM Oncology Impact.

(10) The shares are held as follows: 341,709 by MPM AM, 3,950,528 by BV 2018, 206,964 by BV 2018(B), 77,911 by AM BV2018, 847,080 by MPM Oncology and 4,835,872 by MPM Oncology Impact.

**Remarks:**
This filing is 1 of 2 identical filings due to limitations on number of Reporting Persons. See Form 4 filed by Ansbert Gadicke.

**Signature:** /s/ Luke Evnin  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC, the GP of MPM BioVentures 2018 (B), L  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the managing member of MPM BioVentures 2018 GP LLC, the GP of MPM BioVentures 2018, L.P.  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, managing director of MPM BioVentures 2018 LLC, the manager of MPM Asset Management Investors BV2018 LLC  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, manager of MPM Oncology Innovations Fund GP LLC  
**Date:** 2026-01-14

**Signature:** /s/ Ansbert Gadicke, manager of MPM Oncology Innovations Fund GP LLC, the general partner of MPM Oncology Innovations Fund, L.P.  
**Date:** 2026-01-14

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**