On October 15, 2026 Actinium Pharmaceuticals, Inc. (NYSE American: ATNM) (Actinium or the Company), a pioneer in differentiated targeted radiotherapies with the potential to transform cancer treatment, reported that an oral presentation with early results from the first-in-human Phase 1 study of ATNM-400 in metastatic castration-resistant prostate cancer (mCRPC) will be presented at the 39th Annual Congress of the European Association of Nuclear Medicine (EANM), October 17–21, 2026, in Vienna, Austria.
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The oral presentation will highlight the ongoing first-in-human Phase 1 dose-escalation study of ATNM-400 in mCRPC. ATNM-400 is a first-in-class Actinium-225 (²²⁵Ac) antibody radioconjugate targeting a non-PSMA antigen implicated in tumor survival and treatment resistance. The study will characterize the safety, biodistribution, and dosimetry of Zirconium-89-labeled ATNM-400. Serial PET imaging will assess its tumor uptake, distribution, and clearance, with dosimetry estimates informing therapeutic ²²⁵Ac-ATNM-400 dosing.
"These first clinical data from ATNM-400 mark an important milestone for Actinium and for prostate cancer treatment beyond PSMA," said Sandesh Seth, Actinium’s Chairman and CEO. "As a first-in-class radiotherapeutic targeting an antigen implicated in tumor survival and treatment resistance, ATNM-400 has the potential to serve the broad mCRPC population, including patients with PSMA-low or PSMA-negative disease and those who do not respond to or progress after PSMA-directed therapies. These initial findings mark an important milestone for ATNM-400 and our Actinium-225 development program."
ATNM-400 EANM 2026 Presentation Details
Abstract Title: First-In-Human Phase 1 Study of ATNM-400, Actinium-225 Antibody Radioconjugate, in Metastatic Castration-Resistant Prostate Cancer (mCRPC)
Abstract Number: OP-525
Presentation Type: Oral presentation
Session: 1111 — Theranostics Track: Prostate Cancer Therapy II
Session Date & Time: Monday, October 19, 2026, 4:45–6:15 p.m. CEST | Vienna, Austria
Location: Hall G1
(Press release, Actinium Pharmaceuticals, OCT 15, 2026, View Source [SID1234673481])