Actinium Pharmaceuticals, Inc. announced that results from the Phase 3 SIERRA trial of Iomab-B were presented in an oral presentation at the 50th Annual European Bone Marrow Transplant Society Meeting (EBMT) held in Glasgow, Scotland on April 14-17. The results showed that an Ibomab-B led bone marrow transplant (BMT) results in higher rates of remissions and durable Complete Remission (dCR), which is the primary endpoint of the SIERRA trial, as well as significant improvement in overall survival in TP53 positive patients. Iomab-B is a targeted radiotherapeutic comprised of an anti-CD45 monoclonal antibody with the Iodine-131 radioisotope payload.

The Phase 3 SIERRA trial enrolled 153 patients age 55 and above with active relapsed or refractory acute myeloid leukemia (AML) and compared outcomes of patients receiving Iomab-B BMT to those of patients receiving physician's choice of care in the control arm. In total, 24% (37/153) of the patients enrolled on SIERRA had a TP53 mutation, which is associated with limited treatment options and poor outcomes. Median OS was 6.37 months in TP53 negative patients receiving Iomab-B and 5.72 months for TP53 positive patients demonstrating Iomab-B's ability to overcome TP53 gene mutations.