# EDGAR Filing Document

**Accession Number:** 0001134655
**File Stem:** 0001231919-26-000025
**Filing Date:** 2026-1
**Character Count:** 10455
**Document Hash:** 6e31513c4e3fd0ab15c8ace3bef2ed4b
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001231919-26-000025.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0001231919-26-000025

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 1

**CONFORMED PERIOD OF REPORT**: 20260108

**FILED AS OF DATE**: 20260108

**DATE AS OF CHANGE**: 20260108

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** GADICKE ANSBERT
- **CENTRAL INDEX KEY:** 0001134655

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26521191

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

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Oncology Impact Private Investment Fund 2, L.P.
- **CENTRAL INDEX KEY:** 0002104306

**ORGANIZATION NAME:**
- **STATE OF INCORPORATION:** E9
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26521189

**BUSINESS ADDRESS:**
- **ADDRESS IS A NON US LOCATION:** YES
- **STREET 1:** 89 NEXUS WAY
- **STREET 2:** CAMANA BAY
- **CITY:** GRAND CAYMAN
- **PROVINCE COUNTRY:** E9
- **ZIP:** KY1-9009
- **BUSINESS PHONE:** 1 345 949 9876

**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 ASSET MANAGEMENT LLC
- **CENTRAL INDEX KEY:** 0001263048

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

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26521190

**BUSINESS ADDRESS:**
- **STREET 1:** 399 BOYLSTON STREET, SUITE 1100
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02116
- **BUSINESS PHONE:** 6174259200

**MAIL ADDRESS:**
- **STREET 1:** 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 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>GADICKE ANSBERT<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. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-01-08 | **4. 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>_ _ | **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 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. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-01-08 | **4. 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>_ _ | **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>Oncology Impact Private Investment Fund 2, 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. Issuer Name and Ticker or Trading Symbol**<br>Aktis Oncology, Inc. [ AKTS ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2026-01-08 | **4. 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>_ _ | **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 Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |
| Common Stock | 341709 | I | See Footnote<sup>(1)(2)</sup> |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Series Seed Redeemable Convertible Preferred Stock | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1314262 | 0<sup>(3)</sup> | I | See Footnote<sup>(1)(4)</sup> |
| Series A Redeemable Convertible Preferred Stock | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 5914197 | 0<sup>(3)</sup> | I | See Footnote<sup>(1)(5)</sup> |
| Series B Redeemable Convertible Preferred Stock | <sup>(3)</sup> | <sup>(3)</sup> | Common Stock | 1577119 | 0<sup>(3)</sup> | I | See Footnote<sup>(1)(6)</sup> |

---

### Footnotes:

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

(2) The shares are held by MPM Asset Management LLC, of which Dr. Gadicke is the manager.

(3) Each share of Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock is convertible into shares of the Issuer's Common Stock on a 3.8044-for-1 basis. Upon theclosing of the Issuer's initial public offering, all shares of Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock will convert into shares of Common Stock of the Issuer.
The Series Seed Redeemable Convertible Preferred Stock, Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock have no expiration date.

(4) The shares are held 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 managing member of MPM Oncology Investments 2 LLC, which is the general partner of MPM Oncology Impact.

(5) The shares are held 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: 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.

**Remarks:**
This filing is 1 of 2 identical filings due to limitations on number of Reporting Persons. See Form 3 filed by MPM BioVentures 2018, L.P.

**Signature:** /s/ Ansbert Gadicke  
**Date:** 2026-01-08

**Signature:** /s/ Ansbert Gadicke, manager of MPM Asset Management LLC  
**Date:** 2026-01-08

**Signature:** /s/ Ansbert Gadicke, managing member of MPM Oncology Investments 2 LLC  
**Date:** 2026-01-08

**Signature:** /s/ Ansbert Gadicke, managing member of MPM Oncology Investments 2 LLC, the general partner of Oncology Impact Private Investment Fund 2, L.P.  
**Date:** 2026-01-08

### 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.**