Molecularly Targeted Radiation Agent Facilitates Bone Marrow Transplant in Acute Myeloid Leukemia

More than 20,000 people will be diagnosed with acute myeloid leukemia (AML) in 2023, according to estimates from the American Cancer Society. However, new findings from a multicenter, phase 3 trial suggest that a high-dose, molecularly targeted radiation treatment may allow life-saving bone marrow transplants, contributing to durable complete remission (dCR) at six months in greater than 60 percent of patients with relapsed or refractory AML.

For the study, which received “Abstract of the Year” honors at the Society of Nuclear Medicine and Molecular Imaging (SNMMI) Annual Meeting in Chicago, researchers examined the use of Iomab-B (131-I apamistamab) and subsequent allogeneic hematopoietic cell transplant (HCT) in patients with relapsed or refractory AML. According to the study authors, Iomab-B facilitates myeloablation and eradication of leukemic cells via high-dose, molecular-targeted radiation of hematopoietic cells.

The researchers found that all 66 patients who received Iomab-B underwent HCT in comparison to 14 patients (18.2 percent) who received conventional care in the form of high-dose chemotherapy. Twenty-two percent of the Iomab-B cohort achieved dCR at six months and none of the patients in the conventional care group achieved this primary endpoint. Forty-four patients in the conventional care arm of the study crossed over to the Iomab-B treatment group and 40 of the patients subsequently had HCT, according to the study.

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Emerging Molecularly Targeted Radiation Agent Facilitates Bone Marrow Transplant in Patients with Acute Myeloid Leukemia

In comparison to patients who did not crossover to the Iomab-B arm of the study, those who were treated with Iomab-B had double the survival rate at one year, according to the study authors. The researchers also noted long-term survival of two years or greater in 60 percent of patients who had dCR after treatment with Iomab-B.

“This pivotal study showed that a single personalized dose of Iomab-B enabled all patients who received the therapeutic dose to have access to potentially curative bone marrow transplant compared to only 17 percent of patients who received conventional care. Iomab-B also demonstrated long-term survival benefit for patients who met the primary endpoint, and safety of the Iomab-B led regimen was excellent,” noted lead study author Neeta Pandit-Taskar, M.D., the clinical director of radioimmunotherapy and theranostics at the Ludwig Center for Cancer Immunotherapy at the Memorial Sloan Kettering Cancer Center in New York, New York.

In regard to the safety profile, Pandit-Taskar and colleagues also noted over a 22 percent lower rate of sepsis for patients treated with Iomab-B and HCT (6.1 percent) in comparison to the conventional care cohort (28.6 percent). They also found that Iomab-B had lower rates of febrile neutropenia (43.9 percent versus 50 percent) and mucositis (15.2 percent versus 21.4 percent) in contrast to conventional care.