On May 6, 2026 Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in the development of targeted radiotherapies, reported the upcoming presentation of three abstracts at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) 2026 Annual Meeting, taking place May 30-June 2, 2026, in Los Angeles, California.

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The presentations include two posters on ATNM-400, Actinium’s first-in-class Actinium-225 (225Ac) antibody radioconjugate, demonstrating its potential in prostate cancer and non-small cell lung cancer (NSCLC), as well as a third poster presenting preclinical radiochemistry data on chelator-to-antibody ratio (CAR) optimization that underpins ATNM-400 development. Together, the data underscore Actinium’s scientific leadership in next-generation alpha-emitting radioconjugates.

Sandesh Seth, Actinium’s Chairman and CEO, said, "Data to be presented at SNMMI 2026 further strengthen the profile of ATNM-400 as a first-in-class, radiotherapy with broad solid tumor applicability. In NSCLC, ATNM-400 demonstrates the ability to overcome key resistance mechanisms to both EGFR and KRAS mutations that limit current targeted therapies and support its development as a mutation agnostic agent. In prostate cancer, new data demonstrate its potential in the PSMA negative setting, in addition to promising data in PSMA-high and medium settings further supporting the differentiated profile of ATNM-400. Importantly, as we head toward clinical studies with ATNM-400, we showcase our efforts to maximize ATNM-400’s therapeutic index by utilizing our deep radiochemistry expertise to optimize the CAR. Together, the data to be presented support ATNM-400’s growing potential as a differentiated radiotherapy across multiple high-value solid tumor indications that represent some of oncology’s largest commercial opportunities."

ATNM-400 SNMMI 2026 Presentation Details

Abstract Title: ATNM-400: A First-in-Class Actinium-225 Antibody Radioconjugate Demonstrating Potent PSMA-Independent Efficacy in Prostate Cancer Models
Session: Oncology: Discovery & Translational Meet the Author Session
Date & Time: Tuesday, June 2, 2026 11:30am-12:15pm PT | Los Angeles, California

Abstract Title: ATNM-400: A First-in-Class Actinium-225 Antibody Radioconjugate Demonstrating Durable, Mutation-Agnostic Anti-Tumor Activity in Non-Small Cell Lung Cancer Models
Session: Oncology: Discovery & Translational Meet the Author Session
Date & Time: Tuesday, June 2, 2026, 11:30am-12:15pm PT | Los Angeles, California

Abstract Title: Optimizing Chelator-to-Antibody Ratio Improves Tumor Targeting and Pharmacokinetics of 225Ac-Labeled Antibodies
Session: MTA05 RPSC/CMIIT POPs and Science Pavilion Mixer
Date & Time: Sunday, May 31, 2026, 7:30-8:00pm PT | Los Angeles, California

(Press release, Actinium Pharmaceuticals, MAY 6, 2026, View Source [SID1234665214])