Iomab-B is a targeted radiation therapy that attaches to CD45 (a protein expressed on all types of cancerous blood cells), and then works to destroy a patient’s cancer cells and bone marrow stem cells. Recent findings from a Phase 3 study “resulted in the disappearance of all signs of cancer from treatment for six months in patients 55 years and older with active relapsed or refractory acute myeloid leukemia (AML).”

The Phase 3 SIERRA trial has a primary goal of complete remission (CR) at 6 months and a secondary goal of overall survival (OS) as well as event-free survival (“the length of time after treatment ends that a patient is free of complications or events that treatment was meant to delay or prevent”). Patients also had an improved one year survival rate.

Iomab-B is intended to prepare patients for a bone marrow transplant in a safer and more effective manner than the traditional intensive chemotherapy conditioning. “A bone marrow transplant is often considered the only potential cure for patients with certain blood-borne cancers and blood disorders.” 

Enrollment in the SIERRA trial (153 participants) was completed in the third quarter of 2021 and the last patient was transplanted in the fourth quarter of 2021. Iomab-B was well tolerated and showed lowered rates of:

• Febrile neutropenia (fever and lower than normal number of neutrophils, a type of white blood cell)
• Sepsis (an infection that can lead to organ failure or tissue damage)
• Mucositis (inflamed lining of the digestive system)
• Acute-graft-versus-host-disease (when donated bone marrow or stem cells attacks a patient’s healthy tissue)

Phase 2 of this trial studied 58 patients with advanced AML, age 50 and older. These participants received their transplant on day 28 and 100% of the patients achieved complete remission. Of the 36 relapsed or refractory AML patients, the overall survival rate was 30% at year one and approximately 20% at year two.

Phase 3 treatment with Iomab-B led to 100% engraftment (when the body accepts the transplant) as well as 75% complete remission rate (the disappearance of all signs of cancer) after a bone marrow transplant.

Dr. Avinash Desai, Chief Medical Officer of Actinium Pharmaceuticals states 

“In route clinical (bone marrow transplant) practice, patients enrolled on SIERRA would never be considered for transplant and often have dismal outcomes. Iomab-B provides unprecedented (bone and marrow transplant) access and improves outcomes with better tolerability — opening the promise of better transplant outcomes for the entire universe of relapsed and refractory AML patients."