Actinium Pharmaceuticals Inc. has announced new preclinical research results for ATNM-400, a first-in-class antibody radioconjugate armed with Actinium-225 (Ac-225), at the 32nd Annual Prostate Cancer Foundation Scientific Retreat, held October 23-25, 2025. The data demonstrated that ATNM-400, which targets a novel, non-PSMA antigen, showed superior efficacy and prolonged survival compared to existing PSMA-targeted radioligand therapies in models of low-PSMA and treatment-resistant prostate cancer. Notably, ATNM-400 remained effective even after androgen receptor pathway inhibitor (ARPI) therapy and 177Lu-PSMA-617 therapy. The combination of ATNM-400 with the ARPI enzalutamide achieved complete tumor regression in 40% of treated animals, highlighting promising synergy. Additionally, Actinium is advancing ATNM-400 into non-small cell lung cancer (NSCLC), where it has shown the ability to overcome resistance to EGFR-TKI therapy in preclinical models.