# EDGAR Filing Document

**Accession Number:** 0002035832
**File Stem:** 0000935836-26-000018
**Filing Date:** 2026-1
**Character Count:** 8904
**Document Hash:** da155d94698b7a471a8904f818b52a10
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000935836-26-000018.hdr.sgml**: 20260108

**ACCESSION NUMBER**: 0000935836-26-000018

**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:** NODELMAN OLEG
- **CENTRAL INDEX KEY:** 0001454385

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-43047
- **FILM NUMBER:** 26521152

**MAIL ADDRESS:**
- **STREET 1:** 357 TEHAMA STREET #3
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94103
**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** EcoR1 Capital, LLC
- **CENTRAL INDEX KEY:** 0001587114

**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:** 26521153

**BUSINESS ADDRESS:**
- **STREET 1:** 357 TEHAMA STREET #3
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94103
- **BUSINESS PHONE:** 415-448-6534

**MAIL ADDRESS:**
- **STREET 1:** 357 TEHAMA STREET #3
- **CITY:** SAN FRANCISCO
- **STATE:** CA
- **ZIP:** 94103
**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>EcoR1 Capital, LLC<br><sub>(Last) (First) (Middle)</sub><br>357 TEHAMA STREET #3<br><sub>(Street)</sub><br>SAN FRANCISCO, CA 94103<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>[X] 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>NODELMAN OLEG<br><sub>(Last) (First) (Middle)</sub><br>357 TEHAMA STREET #3<br><sub>(Street)</sub><br>SAN FRANCISCO, CA 94103<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>[X] 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 |

---

## 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 A Redeemable Convertible Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 2605878<sup>(2)</sup> | <sup>(1)</sup> | I | See note<sup>(3)</sup> |
| Series A Redeemable Convertible Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 262142<sup>(2)</sup> | <sup>(1)</sup> | I | See note<sup>(4)</sup> |
| Series A Redeemable Convertible Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 128506<sup>(2)</sup> | <sup>(1)</sup> | I | See note<sup>(5)</sup> |
| Series B Redeemable Convertible Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 630191<sup>(2)</sup> | <sup>(1)</sup> | I | See note<sup>(3)</sup> |
| Series B Redeemable Convertible Preferred Stock | <sup>(1)</sup> | <sup>(1)</sup> | Common Stock | 26942<sup>(2)</sup> | <sup>(1)</sup> | I | See note<sup>(4)</sup> |
| Director Stock Option (Right to Acquire) | <sup>(6)</sup> | 2036-01-07 | Common Stock | 37866 | $18.00 | D<sup>(7)</sup> |  |

---

### Footnotes:

(1) Shares of Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock are convertible into shares of Common Stock at the election of the holder. Each share is immediately exercisable and has no expiration date, but will be automatically converted on a 3.8044-for-1 basis into shares of Common Stock immediately prior to the closing of the initial public offering of the Issuer's Common Stock.

(2) Reflects the number of shares of Common Stock issuable after the 1-for-3.8044 reverse stock split which became effective on January 2, 2026.

(3) These securities are held by EcoR1 Capital Fund Qualified, L.P. ("Qualified Fund"). EcoR1 Capital, LLC ("EcoR1") may be deemed to indirectly beneficially own them as the investment adviser to and general partner of the fund. Mr. Nodelman may be deemed to indirectly beneficially own them as the control person of EcoR1.

(4) These securities are held by EcoR1 Capital Fund, L.P. ("Capital Fund"). EcoR1 may be deemed to indirectly beneficially own them as the investment adviser to and general partner of the fund. Mr. Nodelman may be deemed to indirectly beneficially own them as the control person of EcoR1.

(5) These securities are held by EcoR1 Venture Opportunity Fund, L.P. ("Venture Fund"). EcoR1 may be deemed to indirectly beneficially own them as the investment adviser to and general partner of the fund. Mr. Nodelman may be deemed to indirectly beneficially own them as the control person of EcoR1.

(6) 1/36th of the original number of shares subject to the option shall vest in monthly installments from January 8, 2026, subject to Mr. Nodelman's continuous service through each vesting date, inclusive.

(7) These securities are beneficially owned solely by Mr. Nodelman.

**Remarks:**
EcoR1 is the general partner and investment adviser of private funds, including Qualified Fund, Capital Fund and Venture Fund. Mr. Nodelman is a director of the issuer and is the manager and controlling owner of EcoR1. The reporting persons are filing this Form 3 jointly, but not as a group, and each expressly disclaims membership in a group within the meaning of Rule 13d-5(b) under the Securities Exchange Act of 1934. The reporting persons disclaim beneficial ownership of the securities reported herein, except to the extent of their respective pecuniary interests therein.

**Signature:** /s/ Oleg Nodelman, Manager of EcoR1 Capital, LLC  
**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.**