On June 15, 2021 Actinium Pharmaceuticals reported data from its pivotal Phase 3 SIERRA trial for Iomab-B in an oral presentation at the 2021 Society of Nuclear Medicine and Molecular Imaging (SNMMI) Annual Meeting, which is to be held virtually from June 11th – 14th (Press release, Actinium Pharmaceuticals, JUN 15, 2021, View Source [SID1234584091]). Iomab-B is radiotherapy that targets cells expressing CD45, a protein found only on blood cancer cells and immune cells including bone marrow stem cells, with the radioisotope iodine-131 and is intended to be a targeted conditioning agent to enable potentially curative bone marrow transplant (BMT). The SIERRA trial is the only randomized Phase 3 trial to offer potentially curative BMT as an option for patients with active, relapsed or refractory acute myeloid leukemia (r/r AML) age 55 and above, a patient population not considered eligible for BMT with standard non-targeted conditioning regimens.

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Dr. Mark Berger, Actinium’s Chief Medical Officer, said, "Our enthusiasm for Iomab-B continues to grow at every safety and feasibility update from the pivotal Phase 3 SIERRA trial. With consistently strong engraftment data through 75% of patient enrollment, we believe Iomab-B has the potential to unlock a paradigm shift in the treatment of patients with relapsed and refractory AML. Despite 9 approved drugs for patients with AML since 2017, many of which are targeted agents, AML remains one of the most difficult to treat blood cancers with the lowest 5-year survival rate. In developing Iomab-B our goal is to improve patient outcomes by enabling potentially curative BMT for a large portion of the AML patient population."

SNMMI Presentation Title: Relationship of Marrow Radiation Dose and Timing of Engraftment for Targeted Radioimmunotherapy with Anti-CD45 Iodine (131I) Apamistamab [Iomab-B] in Patients with Active Relapsed or Refractory Acute Myeloid Leukemia

Presenter: Susan Passalaqua, MD, Banner MD Anderson Cancer Center

SNMMI Presentation Highlights:

100% BMT and engraftment rate for patients receiving a therapeutic dose of Iomab-B compared to 18% of patients receiving physician’s choice of salvage therapy on the control arm
79% of all patients enrolled on SIERRA were able to proceed to BMT despite being a patient population not considered eligible for BMT with standard approaches
Iomab-B delivers high amounts of targeted radiation to the bone marrow with minimal impact on other organs resulting in lower rates and severity of adverse events

About Iomab-B
Iomab-B (I-131 apamistamab) is an Antibody Radiation Conjugate (ARC) that is intended to condition or prepare patients for a potentially curative bone marrow transplant (BMT) in a targeted manner with the goal of reducing adverse events and increasing patent access to BMT. Via the monoclonal antibody apamistamab, Iomab-B targets CD45, an antigen widely expressed on leukemia and lymphoma cancer cells, immune cells and stem cells. Apamistamab is linked to the radioisotope iodine-131 (I-131) and once its attached to its target cells, it emits energy that travels about 100 cell lengths, destroying a patient’s cancer cells and ablating their bone marrow. By carrying iodine-131 directly to the bone marrow in a targeted manner, Actinium believes Iomab-B can avoid the side effects of radiation on most healthy tissues while effectively killing the patient’s cancer and marrow cells.

Iomab-B is currently being studied in the pivotal Phase 3 SIERRA (Study of Iomab-B in Relapsed or Refractory AML) trial, a 150-patient, randomized controlled clinical trial in patients with relapsed or refractory Acute Myeloid Leukemia (AML) who are age 55 and above. The SIERRA trial is being conducted at preeminent transplant centers in the U.S. with the primary endpoint of durable Complete Remission (dCR) at six months and a secondary endpoint of overall survival. Upon approval, Iomab-B is intended to prepare and condition patients for a bone marrow transplant, also referred to as a hematopoietic stem cell transplant, in a potentially safer and more efficacious manner than the non-targeted intensive chemotherapy conditioning that is the current standard of care in bone marrow transplant conditioning. A bone marrow transplant is often considered the only potential cure for patients with certain blood-borne cancers and blood disorders. Additional information on the Company’s Phase 3 clinical trial in R/R can be found at www.sierratrial.com.