Iomab-B Conditioning Elicits Durable CR in Relapsed/Refractory AML

Reduced-intensity conditioning treatment plus Iomab-B prior to bone marrow transplant led to a durable and statistically significant 6-month complete remission (CR) rate vs conventional care in older patients with active, relapsed/refractory acute myeloid leukemia (AML), meeting the primary end point of the phase 3 SIERRA trial (NCT02665065; P < .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 bone marrow transplant 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 FDA for approval of Iomab-B,” Avinash Desai, MD, chief medical officer of Actinium, said in a press release.

Iomab-B is a first-in-class targeted radiotherapy designed to improve patient access to potentially curative bone marrow transplant by depleting blood cancer, immune, and bone marrow stem cells that express CD45.

Several studies have shown improved survival in patients receiving bone marrow transplant. However, most patients with blood cancers do not receive bone marrow transplant because current treatments do not elicit a remission, which is required for bone marrow transplant, or are too toxic.

Prior studies have shown widespread access to bone marrow transplant, increased survival, and tolerability with Iomab-B, including the recently completed SIERRA trial.

The company plans to submit a BLA seeking approval for Iomab-B for the treatment of patients aged 55 years or older with relapsed/refractory AML who cannot access bone marrow transplant with currently available therapies. Previously, Iomab-B received orphan drug designation from the FDA, with patent protection into 2037.

The randomized, multi-center, controlled trial compared Iomab-B as a conditioning regimen prior to bone marrow transplant vs physician’s choice of salvage therapy, which allowed all current means of conventional care with the intent to transplant.

The trial enrolled 153 patients 55 years of age or older with active relapsed or refractory AML defined by leukemic blast count greater than 5%. Study investigators enrolled patients at 24 leading transplant centers in the United States and Canada that perform over 30% of AML bone marrow transplants.

Control arm options included cytarabine and daunorubicin, venetoclax (Venclexta), FLT3 inhibitors, and IDH1/2 inhibitors.

Durable CR served as the primary end point; secondary end points included overall survival and event-free survival.

Findings from the full patient enrollment, which were presented at the Transplantation & Cellular Therapy Tandem Meetings in April 2022, showed that all patients who received Iomab-B accessed bone marrow transplant and engrafted without delay.

Iomab-B was also shown to be well tolerated, in line with prior data.

“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 relapsed/refractory 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 officer of Actinium, concluded.

Reference

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. October 31, 2022. Accessed October 31, 2022. https://yhoo.it/3Nn7omz