If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).




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SCHEDULE 13D




Comment for Type of Reporting Person:
Shares reported as beneficially owned represent shares directly held by Lantheus Alpha Therapy, LLC ("Lantheus Alpha"), a wholly owned direct subsidiary of Lantheus Medical Imaging, Inc. ("Lantheus Medical"). Lantheus Medical is the sole member of Lantheus Alpha and a wholly-owned subsidiary of Lantheus Holdings, Inc. ("Lantheus Holdings"). Lantheus Holdings, Lantheus Medical and Lantheus Alpha may each be deemed to have shared voting and dispositive power over all of the shares of Common Stock held by Lantheus Alpha. The percent of class represented by the amount in Row (13) is based upon 114,151,663 shares of the Issuer's Common Stock issued and outstanding as of August 5, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026. Effective June 14, 2024, the Issuer effected a 1-for-10 reverse stock split of its Common Stock (the "Reverse Stock Split"). The number of shares of Common Stock disclosed in this Statement have been adjusted to reflect the Reverse Stock Split.


SCHEDULE 13D




Comment for Type of Reporting Person:
Shares reported as beneficially owned represent shares directly held by Lantheus Alpha, a wholly owned direct subsidiary of Lantheus Medical. Lantheus Medical is the sole member of Lantheus Alpha and a wholly-owned subsidiary of Lantheus Holdings. Lantheus Holdings, Lantheus Medical and Lantheus Alpha may each be deemed to have shared voting and dispositive power over all of the shares of Common Stock held by Lantheus Alpha. The percent of class represented by the amount in Row (13) is based upon 114,151,663 shares of the Issuer's Common Stock issued and outstanding as of August 5, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026. The number of shares of Common Stock disclosed in this Statement have been adjusted to reflect the Reverse Stock Split.


SCHEDULE 13D




Comment for Type of Reporting Person:
Shares reported as beneficially owned represent shares directly held by Lantheus Alpha, a wholly owned direct subsidiary of Lantheus Medical. Lantheus Medical is the sole member of Lantheus Alpha and a wholly-owned subsidiary of Lantheus Holdings. Lantheus Holdings, Lantheus Medical and Lantheus Alpha may each be deemed to have shared voting and dispositive power over all of the shares of Common Stock held by Lantheus Alpha. The percent of class represented by the amount in Row (13) is based upon 114,151,663 shares of the Issuer's Common Stock issued and outstanding as of August 5, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2026. The number of shares of Common Stock disclosed in this Statement have been adjusted to reflect the Reverse Stock Split.


SCHEDULE 13D


 
Lantheus Holdings, Inc.
 
Signature:/s/ Eric M. Green
Name/Title:Eric M. Green, Assistant Corporate Secretary
Date:09/04/2026
 
Lantheus Medical Imaging, Inc.
 
Signature:/s/ Eric M. Green
Name/Title:Eric M. Green, Assistant Corporate Secretary
Date:09/04/2026
 
Lantheus Alpha Therapy, LLC
 
Signature:/s/ Eric M. Green
Name/Title:Eric M. Green, Assistant Corporate Secretary of Lantheus Medical Imaging, Inc., its sole member
Date:09/04/2026

ATTACHMENTS / EXHIBITS

ATTACHMENTS / EXHIBITS

EX-99.A

EX-99.10