Aktis Oncology, Inc. (NASDAQ:AKTS) (Aktis or the Company), a clinical-stage oncology company focused on expanding the breakthrough potential of targeted radiopharmaceuticals to large populations, today announced the initiation of a Phase 1b clinical trial of AKY-25191 in patients with metastatic castration-resistant prostate cancer (mCRPC). The mCRPC-dedicated Phase 1b trial is part of Aktis' clinical development strategy to develop AKY-2519 broadly in B7-H3 expressing tumors. Aktis plans to initiate a Phase 1b basket trial in lung, colorectal, and other high B7-H3 expressing solid tumors in the second half of 2026.