Novel Targeted Radiotherapy May Lead to 6-Month Complete Remission in Relapsed/Refractory AML

Preliminary findings from a phase 3 trial demonstrated that treatment with a novel targeted radiotherapy 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).

In the SIERRA trial, iomab-B also had a significant improvement in 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), according to a press release from Actinium, the manufacturer of the therapy. In particular, iomab-B conferred a 78% reduction in the likelihood that a patient would have an event.

Iomab-B is a targeted radiotherapy that aims to improve access to bone marrow transplant by rapidly and simultaneously depleting blood cancer, immune and bone marrow stem cells that express CD45, according to the release. Of note, CD45 is a protein that plays a role in AML development and maintenance.

Patients with relapsed or refractory AML who were treated with iomab-B also had an improved one-year survival rate compared with those assigned physician’s choice of treatment (26.1% versus 13.1%). This improvement was also seen regarding overall survival (the time when a patient with cancer is still alive), with 6.4 months in the iomab-B group and 3.2 months in the physician’s choice group, according to the release.

“The SIERRA trial results are an exciting advancement for older patients with active (relapsed or refractory) AML and will be practice changing in how we treat these patients,” Dr. Sergio Giralt, deputy head of the division of hematologic malignancies at Memorial Sloan Kettering Cancer Center in New York, said in the release. “I am thrilled to see a high percentage of iomab-B patients who achieved durable remissions reaching the critical two-year survival mark. Significant improvement in event-free survival and overall survival, with an excellent safety profile in the SIERRA trial, demonstrate the potential of iomab-B becoming a new standard of care for active (relapsed or refractory) AML.”

Iomab-B was well tolerated in patients with AML and led to lower rates of febrile neutropenia (fever and lower than normal number of neutrophils, a type of white blood cell, in blood), sepsis (an immune response to infection that can lead to organ failure, tissue damage or death if not treated immediately), mucositis (inflammation of the lining of the digestive system) and acute graft-versus-host disease (a condition when donated bone marrow or stem cells attacks health tissues in a patient’s body) compared with those assigned physician’s choice of treatment.

In addition, treatment with iomab-B led to access to bone marrow transplants with 100% engraftment (when the body accepts the transplant and produces new blood cells as a result) in patients in the iomab-B group compared with 18% in patients assigned physician’s choice. Iomab-B also resulted in a 75% complete remission rate (the disappearance of all signs of cancer from treatment) after a bone marrow transplant versus 6.3% in patients assigned physician’s choice, according to the release.

“We are excited that iomab-B met the primary endpoint and produced positive results across all SIERRA trial endpoints with improved safety compared to (the) control arm in such a difficult patient population,” Dr. Avinash Desai, chief medical officer of Actinium, said in the release. “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.”

Researchers conducting the SIERRA trial enrolled 153 patients aged 55 years and older with active relapsed/refractory AML and high-risk factors that would permit them to be offered bone marrow transplantation in standard practice. This trial aimed to compare iomab-B with the control arm, in which the physician made a choice from 20 different agents including targeted therapies and/or chemotherapies, according to the release. The physician’s choice of treatment was meant to reflect the current best practices for the treatment of this patient population.

For more news on cancer updates, research and education, don’t forget to subscribe to CURE®’s newsletters here.