Relapsed or refractory Acute Myeloid Leukemia (AML) remains one of the most difficult cancers to treat. Most patients do not respond to standard chemotherapy, and survival is often measured in months, not years. Now, researchers at the MCW Cancer Center are testing a more precise approach—radioimmunotherapy. This cutting-edge treatment uses an antibody to deliver radiation directly to cancer cells, helping destroy them while minimizing damage to healthy tissue.
In a recently completed phase 1 trial led by Sameem Abedin, MD, Associate Professor of Hematology and Oncology and Clinical Trials Office Medical Director, researchers evaluated whether the antibody-based treatment, lintuzumab-Ac225, could improve remission rates when combined with salvage chemotherapy. Their findings, recently published in Leukemia, showed strong responses in patients with high-risk or treatment-resistant cases.
“While salvage therapy is standard for relapsed AML, only about 30% of patients respond, and the response typically lasts just eight months. In this study, our goal was to target disease that resists chemotherapy by using focused radiotherapy delivered through a targeted antibody—and the results are encouraging.” — Sameem Abedin, MD
The trial enrolled 26 patients, many with aggressive forms of AML or TP53 mutations, which are often associated with poor outcomes. Results showed:
- 62% achieved remission at the recommended dose
- 79% of those with only one or two prior treatments responded
- 5 patients were able to receive a stem cell transplant, which offers the best chance for long-term survival in AML when patients are in remission
- 67% of responders had no measurable leukemia left after treatment, a result known as measurable residual disease (MRD)–negative
MRD-negativity was confirmed using flow cytometry, a highly sensitive detection method that examines hundreds of thousands of cells from blood or bone marrow. The advanced diagnostic tool use fluorescent antibodies to highlight abnormal markers, making it possible to detect even one cancer cell among 10,000 healthy ones.
“Flow cytometry allows us to detect disease that would otherwise go unnoticed using standard methods. That level of precision is critical not only for understanding how well a therapy is working, but for shaping the next steps in a patient’s treatment plan.” — Tyce Kearl, MD, PhD, Assistant Professor, Hematology and Oncology, Technical Director, Cancer Center Cell Therapy Shared Resource
The treatment was also well tolerated, with side effects primarily related to low blood counts, which are common with intensive chemotherapy. Importantly, no significant liver-related side effects were seen, which is a concern with other antibody-based treatments.
The MCW Cancer Center is one of only a few institutions nationwide advancing research in radioimmunotherapy for AML. Investigators are now developing a larger phase 2/3 trial to further test the approach and move it closer to becoming a standard treatment option.
“This study—and particularly the next—aims to help make radioimmunotherapy a regular part of how we treat AML,” said Dr. Abedin. “I’m really excited for the patients who are thriving today and beating really challenging odds.”
Read the full study in Leukemia.