Actinium shares surge 14.49% premarket after ATNM-400 data presented at SABCS shows efficacy in resistant breast cancer.

Actinium Pharmaceuticals surged 14.49% in premarket trading following the announcement of compelling preclinical data for its lead candidate, ATNM-400, demonstrating potent efficacy in triple-negative breast cancer and overcoming resistance to endocrine and HER2-targeted therapies. The data, to be presented at the San Antonio Breast Cancer Symposium, highlights ATNM-400’s ability to inhibit tumor growth in resistant models while potentially avoiding off-target toxicities like interstitial lung disease, which limits antibody drug conjugates. The drug’s differentiated alpha-particle radiotherapy mechanism and pan-tumor potential across prostate, lung, and breast cancers further underscore its therapeutic and commercial promise, addressing high-unmet-need oncology markets.