Actinium Pharmaceuticals Presents New Data on ATNM-400 at Lung Cancer Conference

Actinium Pharmaceuticals on June 2 presented new preclinical data on ATNM-400 in non-small cell lung cancer, or NSCLC, at the Society of Nuclear Medicine and Molecular Imaging 2026 Annual Meeting in Los Angeles, California. The new KRAS-mutant data, together with a growing body of EGFR-mutant data, demonstrate ATNM-400's activity across the two major mutation driver classes in NSCLC and support a distinct strategic opportunity. ATNM-400 can be developed as a potential mutation-agnostic backbone for the broader NSCLC market, alone or in combination with standard-of-care therapies, rather than as another mutation-specific drug for a narrow subset. NSCLC accounts for roughly 85% of the more than two million lung cancer cases diagnosed globally each year, a market more than twice the size of prostate cancer. It is also highly heterogeneous: no single mutation dominates, so treatments are fragmented across mutation-specific therapies such as EGFR, KRAS, BRAF, ALK and others, each marketed by different companies, each addressing only a molecular subset, and each ultimately limited by acquired resistance. ATNM-400, Actinium-225 antibody radioconjugate, is designed to break out of that single-mutation paradigm. Rather than blocking a specific mutant protein, it delivers a high-linear-energy-transfer alpha-particle payload that induces dense, irreversible double-strand DNA breaks and tumor-cell death independent of a tumor's driver mutation or signaling pathway, the mechanistic basis of its mutation-agnostic activity. In new KRAS-mutant studies presented at SNMMI, sotorasib and adagrasib increased ATNM-400's target up to 3.5- and 3.8-fold, respectively, and adding ATNM-400 deepened tumor-cell killing beyond either inhibitor alone. These results demonstrate the same target-expression increasing, synergy-enabling biology shown previously with the EGFR inhibitor osimertinib, which produced tumor growth inhibition of 107% when combined with ATNM-400. These combination benefits also broaden ATNM-400's commercial opportunity. The franchises it could enhance are substantial; the KRAS inhibitor class in NSCLC is projected to exceed $5B in peak sales, and the EGFR-mutant segment has peak sales estimates over $15B, led by osimertinib which generated $7.3B in 2025. This positions ATNM-400 to participate in these established markets by enhancing the standard of care, while also reaching the broader NSCLC population beyond any single mutation.