Actinium Announces Positive Full Data Results From the Pivotal Phase 3 SIERRA Trial in Patients with Active, Relapsed or Refractory Acute Myeloid Leukemia

Actinium Pharmaceuticals, a leader in the development of targeted radiotherapies, today announced positive results for the primary and secondary endpoints from its pivotal Phase 3 SIERRA trial of Iomab-B in patients age 55 and above with active relapsed or refractory acute myeloid leukemia (r/r AML).

Iomab-B met the primary endpoint of durable Complete Remission (dCR) of 6-months following initial complete remission following BMT with a high degree of statistical significance (p<0.0001). Additionally, Iomab-B produced a significant and clinically meaningful improvement in the secondary endpoint of Event-Free Survival (EFS), with a 78% reduction in the probability of an event (Hazard Ratio=0.22, p<0.0001). Iomab-B doubled 1-year survival compared to the control arm excluding cross over patients (26.1% vs 13.1%) as well as median overall survival (6.4 months vs. 3.2 months). Iomab-B was well tolerated with four times lower rates of sepsis (6.1% vs 28.6%) and lower rates of febrile neutropenia, mucositis and acute graph versus host disease (aGVHD). Iomab-B enabled unprecedented access to BMT with 100% engraftment in patients receiving a therapeutic dose of Iomab-B compared to 18% of patients in the control arm and Iomab-B produced a 75% post-BMT Complete Remission (CR) rate compared to 6.3% post-BMT CR in the control arm.

These high rates of access and post-BMT CR enabled the highly significant primary endpoint results. The full SIERRA results were presented in the late-breaker session at the 2023 Tandem Meetings: Transplantation & Cellular Therapy Meetings of the American Society for Transplantation and Cellular Therapy (ASTCT) and the Center for International Blood & Marrow Transplant Research (CIBMTR).

Dr. Sergio Giralt, Deputy Head, Division of Hematologic Malignancies, Attending Physician, Adult BMT Service at Memorial Sloan Kettering Cancer Center, stated, “The SIERRA trial results are an exciting advancement for older patients with active r/r AML and will be practice changing in how we treat these patients. I am thrilled to see a high percentage of Iomab-B patients who achieved durable remissions reaching the critical 2-year survival mark. Significant improvement in event-free survival and overall survival, with an excellent safety profile in the SIERRA trial, demonstrate the potential of Iomab-B becoming a new standard of care for active, r/r AML.”