Iomab-B Shows Durable Remission in Elderly Patients With R/R AML

According to results from the SIERRA trial, Iomab-B may be an effective choice for patient with relapsed or refractory acute myeloid leukemia who are 55 years of age or older.

Topline results show durable complete remission (DCR) of 6 months post initial remission after a bone marrow transplant was achieved with I apamistamab (Iomab-B), demonstrating a superior result compared with conventional care in older patients with relapsed or refractory acute myeloid leukemia (AML).1

The results are from the phase 3 SIERRA trial (NCT02665065) and were reported in a press release by Actinium Pharmaceuticals, Inc. With the DCR shown in the Iomab-B arm, the study met its primary end point with a statistical significance of <.0001.

“We are excited that the randomized, controlled, multi-center, pivotal SIERRA trial has delivered these results for patients that need new treatment options. Our goal is to increase access to BMT and improve patient outcomes with Iomab-B, and these topline results move us in this direction given their statistical significance. We will continue to work on our Biologics License Application (BLA) submission to the US Food and Drug Administration (FDA) for approval of Iomab-B, said Avinash Desai, PhD, chief medical officer, Actinium, in a press release.

Previously, in the SIERRA study, it was reported that Iomab-B lead to a high transplantation rate. Moreover, following Iomab-B conditioning and alloHCT, the study subjects achieved 100% neutrophil and platelet engraftment. These results were from 75 older patients included in the preliminary analysis. Overall, the data demonstrated Iomab-B’s ability to achieve significant improvements in the current transplantation rates observed in older patients with relapsed or refractory AML.

SIERRA is a study of 153 patients aged 55 or older with relapsed or refractory AML who are randomized to receive Iomab-B with allogeneic hematopoietic cell transplant (alloHCT) or conventional therapy with alloHCT. Conventional therapy in the control arm may consist of chemotherapy with either cytarabine and daunorubicin, or targeted therapy with a Bcl-2 inhibitor, FLT3 inhibitor, or IDH 1/2 inhibitor. The study is exploring the secondary end points of event-free survival, and overall survival.2

"This is a significant milestone in Actinium's lifecycle and a testimony to the quality of our team who undertook a pioneering study in a patient population that is considered largely futile to treat. Despite being perennially under-staffed and under-resourced, their passion and perseverance has yielded a clinically meaningful dividend. Our recently strengthened team is executing to enable our mission to disrupt the field of bone marrow conditioning with Iomab-B, first in r/r AML and then by building upon its robust prior clinical results in several hematological diseases. We look forward to sharing additional clinical data from the SIERRA trial by year end,” Sandesh Seth, chairman, and chief executive office, Sandesh Seth, Actinium said, in the press release.1


1. Actinium announces positive top-line results from pivotal Phase 3 SIERRA trial of Iomab-B in patients with active relapsed or refractory acute myeloid leukemia. News release. Actinium Pharmaceuticals, Inc.

2. Study of Iomab-B vs. conventional care in older subjects with active, relapsed or refractory acute myeloid leukemia (SIERRA). Updated February 24, 2022. Accessed October 31, 2022.