# EDGAR Filing Document

**Accession Number:** 0002035832
**File Stem:** 0000935836-26-000046
**Filing Date:** 2026-1
**Character Count:** 19455
**Document Hash:** 11f17c3ee2440e854c3f65798d8a2ffa
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000935836-26-000046.hdr.sgml**: 20260120

**ACCESSION NUMBER**: 0000935836-26-000046

**CONFORMED SUBMISSION TYPE**: SCHEDULE 13D

**PUBLIC DOCUMENT COUNT**: 2

**FILED AS OF DATE**: 20260120

**DATE AS OF CHANGE**: 20260120

**SUBJECT COMPANY**: 

**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

**FILING VALUES:**
- **FORM TYPE:** SCHEDULE 13D
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 005-95421
- **FILM NUMBER:** 26542305

**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
**FILED BY**: 

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

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

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

**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

## Exhibit 99.1

EXHIBIT 99.1

AGREEMENT REGARDING JOINT FILING

OF STATEMENT ON SCHEDULE 13D OR 13G

The undersigned agree to file jointly with the Securities and Exchange Commission (the "SEC") any and all statements on Schedule 13D or Schedule 13G or Forms 3, 4 or 5(and any amendments or supplements thereto) required under section 13(d) and 16(a) of the Securities Exchange Act of 1934, as amended, in connection with purchases by the undersigned of the securities of any issuer. For that purpose, the undersigned hereby constitute and appoint EcoR1 Capital, LLC, a Delaware limited liability company, as their true and lawful agent and attorney-in-fact, with full power and authority for and on behalf of the undersigned to prepare or cause to be prepared, sign, file with the SEC and furnish to any other person all certificates, instruments, agreements and documents necessary to comply with section 13(d) and section 16(a) of the Securities Exchange Act of 1934, as amended, in connection with said purchases, and to do and perform every act necessary and proper to be done incident to the exercise of the foregoing power, as fully as the undersigned might or could do if personally present.

Dated: January 20, 2026

---

| |
|:---|
| &nbsp;&nbsp; **ECOR1 CAPITAL, LLC**<br>By: <u>/s/ *Oleg Nodelman*</u> <br> Oleg Nodelman<br> Manager<br>|
| &nbsp;&nbsp; **ECOR1 CAPITAL FUND QUALIFIED, L.P.<br>** <br> By: EcoR1 Capital, LLC,<br> General Partner<br>By: <u>/s/ *Oleg Nodelman*</u> <br> Oleg Nodelman<br> Manager<br>|
| &nbsp;&nbsp; <br> <u>/s/ *Oleg Nodelman*</u> <br> Oleg Nodelman |

---

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

## SCHEDULE 13D

### Under the Securities Exchange Act of 1934

**Aktis Oncology, Inc.**

*(Name of Issuer)*

**Common Stock**

*(Title of Class of Securities)*

**01021M104**

*(CUSIP Number)*

**Anthony J. Caldwell, Esq.**<br>Shartsis Friese LLP<br>425 Market Street, 11th Floor<br>San Francisco CA 94105<br>(415) 421-6500

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

**01/12/2026**

*(Date of Event Which Requires Filing of this Statement)*

| **CUSIP No.** | **01021M104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**EcoR1 Capital, LLC** | Name of reporting person<br>**EcoR1 Capital, 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>**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>**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>**4824469.00** |
| 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>**4824469.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**4824469.00** | Aggregate amount beneficially owned by each reporting person<br>**4824469.00** | |
| 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>**9.1%** | Percent of class represented by amount in Row (11)<br>**9.1%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IA** | Type of Reporting Person (See Instructions)<br>**IA** | |

---

**Comment for Reporting Person:** Percentage calculated based on 53,296,950 shares of Common Stock outstanding following the Issuer's initial public offering, as reported in the prospectus filed by the Issuer on January 9, 2026.

| **CUSIP No.** | **01021M104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**Oleg Nodelman** | Name of reporting person<br>**Oleg Nodelman** | |
| 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>**37866.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 8 | Shared Voting Power<br>**4824469.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 9 | Sole Dispositive Power<br>**37866.00** |
| Number of Shares<br>Beneficially Owned by<br>Each Reporting Person With: | 10 | Shared Dispositive Power<br>**4824469.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**4862335.00** | Aggregate amount beneficially owned by each reporting person<br>**4862335.00** | |
| 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>**9.1%** | Percent of class represented by amount in Row (11)<br>**9.1%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**IN** | Type of Reporting Person (See Instructions)<br>**IN** | |

---

**Comment for Reporting Person:** The shares reported herein include 37,866 shares of Common Stock issuable under stock options granted to Mr. Nodelman in his capacity as a director of the Issuer.  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.

Percentage calculated based on 53,296,950 shares of Common Stock outstanding following the Issuer's initial public offering, as reported in the prospectus filed by the Issuer on January 9, 2026.

| **CUSIP No.** | **01021M104** |

---

| | | | |
|:--|:--|:--|:--|
| 1 | Name of reporting person<br>**EcoR1 Capital Fund Qualified, L.P.** | Name of reporting person<br>**EcoR1 Capital Fund Qualified, L.P.** | |
| 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>**4348658.00** |
| 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>**4348658.00** |
| 11 | Aggregate amount beneficially owned by each reporting person<br>**4348658.00** | Aggregate amount beneficially owned by each reporting person<br>**4348658.00** | |
| 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>**8.2%** | Percent of class represented by amount in Row (11)<br>**8.2%** | |
| 14 | Type of Reporting Person (See Instructions)<br>**PN** | Type of Reporting Person (See Instructions)<br>**PN** | |

---

**Comment for Reporting Person:** Percentage calculated based on 53,296,950 shares of Common Stock outstanding following the Issuer's initial public offering, as reported in the prospectus filed by the Issuer on January 9, 2026.

**Item 1. Security and Issuer**

**(a) Title of Class of Securities:**
Common Stock

**(b) Name of Issuer:**
Aktis Oncology, Inc.

**(c) Address of Issuer's Principal Executive Offices:**
17 DRYDOCK AVENUE, SUITE #17-401, BOSTON, MA, 02210

**Item 4. Purpose of Transaction**

Oleg Nodelman, the manager of EcoR1, is a member of the Issuer's board of directors.  The reporting persons acquired securities of the Issuer for investment purposes based on their belief that the Issuer's securities represented an attractive investment opportunity.  The reporting persons will routinely monitor the Issuer regarding a wide variety of factors that affect their investment considerations, including, current and anticipated future trading prices of the Common Stock and other securities, the Issuer's operations, assets, prospects, financial position, and business development, Issuer's management, Issuer-related competitive and strategic matters, general economic, financial market and industry conditions, and other investment considerations. Depending on their evaluation of various factors, the reporting persons may take such actions regarding their holdings of the Issuer's securities as they deem appropriate in light of circumstances existing from time to time. Such actions may include purchasing additional Common Stock in the open market, through privately negotiated transactions with third parties or otherwise, converting shares of Class A Common Stock into shares of Common Stock and selling at any time, in the open market, through privately negotiated transactions with third parties or otherwise, all or part of the Common Stock or other securities that they now own or hereafter acquire. The reporting persons also may from time to time enter into or unwind hedging or other derivative transactions with respect to the Common Stock or pledge their interests in the Common Stock and other securities to obtain liquidity. In addition, from time to time the reporting persons and their representatives and advisers may communicate with other stockholders, industry participants and other interested parties about the Issuer.

The reporting persons have no present plan or proposal that relates to or would result in any of the actions specified in clauses (a) through (j) of Item 4 of Schedule 13D.  However, as noted above, Mr. Nodelman serves on the Issuer's board of directors, and the reporting persons may recommend action to the Issuer's management, board of directors and stockholders. Any such actions could involve one or more of the events referred to in clauses (a) through (j) of Item 4 of Schedule 13D, including, potentially, one or more mergers, consolidations, sales or acquisitions of assets, changes in control, issuances, purchases, dispositions or pledges of securities or other changes in capitalization.

**Item 5. Interest in Securities of the Issuer**

**(a)**
EcoR1:  4,824,469

Oleg Nodelman:  4,862,335

Qualified Fund:  4,348,658

Aggregate percentage of the class of Common Stock beneficially owned by the reporting persons:

EcoR1:  9.1%

Oleg Nodelman:  9.1%

Qualified Fund:  8.2%

**(b)**
(i)  Sole power to vote or to direct the vote:

EcoR1:  0

Oleg Nodelman:  37,866

Qualified Fund:  0

(ii)  Shared power to vote or to direct the vote:

EcoR1:  4,824,469

Oleg Nodelman:  4,824,469

Qualified Fund:  4,348,658

(iii)  Sole power to dispose or to direct the disposition of:

EcoR1:  0

Oleg Nodelman:  37,866

Qualified Fund:  0

(iv)  Shared power to dispose or to direct the disposition of:

EcoR1:  4,824,469

Oleg Nodelman:  4,824,469

Qualified Fund:  4,348,658

**(c)**
In the 60 days preceding the date of this Schedule 13D, the reporting persons engaged in the transactions in the Issuer's Common Stock described in Item 3 above.

**Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.**

EcoR1 is the investment adviser to its clients pursuant to investment management agreements or limited partnership agreements providing to EcoR1 the authority, among other things, to invest the funds of such clients in Stock, to vote and dispose of Stock and to file this statement on behalf of such clients. Pursuant to such limited partnership agreements, EcoR1 is entitled to allocations based on assets under management and realized and unrealized gains.  Pursuant to such investment management agreements, EcoR1 is entitled to fees based on assets under management and realized and unrealized gains.

The Funds hold the aggregate amount of 1,051,412 shares of the Issuer's Class A Common Stock.  Each share of Class A Common Stock is convertible into one share of the Issuer's Common Stock at the holder's election, provided that the shares may not be converted if doing so would result in EcoR1 or any of the Funds beneficially owning more than 4.99% of the outstanding shares of Common Stock.  Due to this limitation, the shares of Class A Common Stock held by the Funds are not presently convertible.

The Funds are party to a Third Amended and Restated Investors' Rights Agreement, dated September 20, 2024, with the Issuer (the "Rights Agreement"). The Rights Agreement grants certain rights to the Funds, including certain demand, piggyback and Form S-3 registration rights with respect to the registrable securities held by them. The terms and provisions of the Rights Agreement are described more fully in the Issuer's Registration Statement on Form S-1/A (File No. 333-292283) declared effective by the Commission on January 7, 2026 (the "Registration Statement"), and the above summary is qualified by reference to such description and the full text of the Rights Agreement, which is filed as Exhibit 99.2 to this Schedule 13D and is incorporated herein by reference.

In connection with the initial public offering of the Issuer's Common Stock, each of the Funds and Mr. Nodelman has entered into lock-up agreements, pursuant to which each of them have agreed, subject to certain exceptions, not to sell, transfer or otherwise convey any of the Issuer's securities held by the Funds for 180 days following the date of the offering. The terms and provisions of such lock-up agreements are described more fully in the Registration Statement, and the above summary is qualified by reference to such description and the full text of the lock-up agreement, a form of which is filed as Exhibit 99.3 to this Schedule 13D and is incorporated herein by reference.

Mr. Nodelman, in his capacity as a director, may be entitled to receive cash compensation and equity compensation, including stock option or other equity awards, pursuant to the Issuer's 2026 Equity Incentive Plan (the "2026 Plan"), and the Issuer's non-employee director compensation policy (the "Compensation Plan"). The terms and provisions of the 2026 Plan and the Compensation Plan are described in the Registration Statement, and the above summary is qualified by reference to such description and the full text of which is filed as Exhibit 99.4 and Exhibit 99.5 to this Schedule 13D and are incorporated herein by reference. In addition, the Issuer has entered into an indemnification agreement with each of its directors and executive officers, including Mr. Nodelman. The indemnification agreement requires the Issuer, among other things, to indemnify Mr. Nodelman for some expenses, including attorneys' fees, judgments, fines and settlement amounts incurred by him in any action or proceeding arising out of his services as director. The terms and provisions of the indemnification agreement are described more fully in the Registration Statement, and the above summary is qualified by reference to such description and the full text of the Registration Statement, which is filed as Exhibit 99.6 to this Schedule 13D and is incorporated herein by reference.

### 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:** EcoR1 Capital, LLC

**Signature:** /s/ Oleg Nodelman

**Name/Title:** Manager

**Date:** 01/20/2026

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:** Oleg Nodelman

**Signature:** /s/ Oleg Nodelman

**Name/Title:** Reporting person

**Date:** 01/20/2026

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:** EcoR1 Capital Fund Qualified, L.P.

**Signature:** /s/ Oleg Nodelman

**Name/Title:** Manager of the General Partner, EcoR1 Capital, LLC

**Date:** 01/20/2026