Positive Phase III results for Actinium's Iomab-B

US biotech Actinium Pharmaceuticals (NYSE: ATNM) saw its shares rise as much as 21%, after it announced positive results for the primary and secondary endpoints from its pivotal Phase III SIERRA trial of Iomab-B in patients age 55 and above with active relapsed or refractory acute myeloid leukemia (r/r AML).

Actinium noted that Iomab-B met the primary endpoint of durable Complete Remission (dCR) of six-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 one-year survival compared to the control arm excluding cross over patients (26.1% versus 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.