Statement of Changes in Beneficial Ownership (Form 4)

FORM 4 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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person * EcoR1 Capital, LLC 2. Issuer Name and Ticker or Trading Symbol Aktis Oncology, Inc. [AKTS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 357 TEHAMA STREET #3 3. Date of Earliest Transaction (Month/Day/Year) 01/12/2026 (Street) SAN FRANCISCO, CA 94103 4. If Amendment, Date Original Filed (Month/Day/Year) 6. Individual or Joint/Group Filing (Check Applicable Line) ___ Form filed by One Reporting Person _X_ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 01/12/2026 C 2,270,879 A (1) 2,270,879 I See Note(2) Common Stock 01/12/2026 C 202,862 A (1) 202,862 I See Note(3) Common Stock 01/12/2026 C 128,506 A (1) 128,506 I See Note(4) Common Stock 01/12/2026 P 2,077,779 A $18 4,348,658 I See Note(2) Common Stock 01/12/2026 P 144,443 A $18 347,305 I See Note(3)

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Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Underlying Securities (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series A Redeemable Convertible Preferred Stock	(1)	01/12/2026		C			9,913,810	(1)	(1)	Common Stock	2,605,878	(1)	0	I	See note(2)
Series A Redeemable Convertible Preferred Stock	(1)	01/12/2026		C			997,299	(1)	(1)	Common Stock	262,142	(1)	0	I	See note(3)
Series A Redeemable Convertible Preferred Stock	(1)	01/12/2026		C			488,891	(1)	(1)	Common Stock	128,506	(1)	0	I	See note(4)
Series B Redeemable Convertible Preferred Stock	(1)	01/12/2026		C			2,397,500	(1)	(1)	Common Stock	630,191	(1)	0	I	See note(2)
Series B Redeemable Convertible Preferred Stock	(1)	01/12/2026		C			102,500	(1)	(1)	Common Stock	26,942	(1)	0	I	See note(3)
Class A Common Stock	(5)	01/12/2026		C		965,190		(5)	(5)	Common Stock	965,190	(1)	965,190	I	See note(2)
Class A Common Stock	(5)	01/12/2026		C		86,222		(5)	(5)	Common Stock	86,222	(1)	86,222	I	See Note(3)

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
EcoR1 Capital, LLC 357 TEHAMA STREET #3 SAN FRANCISCO, CA 94103	X
NODELMAN OLEG 357 TEHAMA STREET #3 SAN FRANCISCO, CA 94103	X

Signatures

/s/ Oleg Nodelman, Individually, and as Manager of EcoR1 Capital, LLC		01/12/2026
**Signature of Reporting Person		Date

Explanation of Responses:

*	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).
(1)	The shares of Series A Redeemable Convertible Preferred Stock and Series B Redeemable Convertible Preferred Stock converted into shares of Common Stock and Class A Common Stock on a 3.8044-for-1 basis immediately prior to the closing of the initial public offering of the Issuer's Common Stock for no additional consideration. Each share was immediately exercisable and had no expiration date.
(2)	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.
(3)	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.
(4)	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.
(5)	Each share of Class A Common Stock is convertible into one share of Common Stock at the election of the holder for no additional consideration, subject to a 4.99% beneficial ownership limitation. Each share is immediately exercisable and has no expiration date.
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 4 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.

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