Interim data from the SIERRA trial of Iomab-B shows side effect differences in Acute Myeloid Leukemia patients.- Actinium Pharma

Actinium Pharmaceuticals announced findings from the SIERRA trial of Iomab-B (monoclonal antibody BC8 / I-131) in Elderly Relapse/Refractory Acute Myeloid Leukemia. It revealed that there were key differences in side effects reported in patients treated in the Iomab-B and control arms of the study with rates of febrile neutropenia, sepsis and mucositis being markedly lower in the Iomab-B arm. The presentation also featured updated results from the fifty percent enrollment mid-point analysis including BMT access rates, engraftment and 100-day non-relapse transplant related mortality (TRM). After accounting for these factors, the results showed that, on an intent-to-treat or ITT basis, 78 percent of patients in the Iomab-B arm are potentially evaluable for the primary endpoint compared to 13 percent in the control arm. In addition, an important and recent protocol amendment was highlighted; the approximately 30 percent of patients who are expected to fail induction therapy with venetoclax plus hypomethylating agents1 are now eligible for enrollment in the SIERRA trial. The change is expected to increase the addressable patient population of the study given that this combination is now recommended as part of the NCCN or National Comprehensive Cancer Network guidelines, is widely used and expected to become the treatment of choice. Patients receiving Iomab-B showed lower rates of key adverse events relevant in the BMT setting in compared to patients randomized to receive physician's choice of salvage chemotherapy on the control arm. For example, patients receiving Iomab-B had a much lower incidence of sepsis of 3 percent compared to the 42 percent incidence in the control arm. In addition, 100 percent (31/31) of patients receiving a therapeutic dose of Iomab-B achieved successful BMT engraftment with only a 6 percent (2/31) TRM rate compared to the control arm where 18 percent (7/38) achieved engraftment with a 29 percent (2/7) TRM rate. At the 100-day post BMT time point, on an ITT basis, there were 29 patients from the Iomab-B study arm potentially evaluable for the primary endpoint of durable Complete Remission (dCR) at 180 days compared to 5 patients in the control arm. By this measure, 78 percent of patients in the Iomab-B arm are potentially eligible for the dCR primary endpoint compared to 13 percent of patients in the control arm. Data were presented at the 2020 Transplantation & Cellular Therapy Meetings of ASTCT and CIBMTR.