Actinium Pharmaceuticals Oral Presentation at SNMMI 2026 Highlights ATNM-400 Overcoming Resistance to All Three Approved Androgen Receptor Inhibitors and Offers Flexible, Well-Tolerated Dosing in Prostate Cancer Models

New data demonstrated ATNM-400 remains potently active in prostate cancer cells and tumors resistant to all three approved androgen receptor inhibitors (ARPIs) -enzalutamide (Xtandi®), apalutamide (Erleada®), and darolutamide (Nubeqa®)- directly targeting the point of failure for a high proportion of mCRPC patients   ATNM-400 substantially outperformed apalutamide and darolutamide in an ARPI-resistant tumor model, and in combination with either ARPI it showed durable complete responses, supporting both monotherapy and combination strategies in refractory disease similar to prior data with enzalutamide  ATNM-400 delivered superior tumor control as a single bolus or repeat dose with a consistent safety profile and minimal off-target toxicity across treatment regimens, indicating dosing flexibility and a wide therapeutic window that could de-risk clinical translation. In high PSMA expressing disease, ATNM-400 outperformed 177Lu-PSMA-617 in terms of activity and was similar to 225Ac-PSMA-617.