CHICAGO – A first-in-class antibody targeting the macrophage checkpoint CD47 is a promising novel immunotherapy in non-Hodgkin lymphoma, according to Ranjana H. Advani, MD, of Stanford (Calif.) Cancer Institute.
Treatment with Hu5F9-G4 (5F9), an antibody designed to overcome the “don’t eat me” signal associated with CD47, produced “encouraging” antitumor activity in a phase 1b study of 22 patients, Dr. Advani said in an oral abstract presentation at the annual meeting of the American Society of Clinical Oncology.
“5F9 was well tolerated in combination with rituximab, with no maximum tolerated dose achieved,” said Dr. Advani, noting that there were complete remissions in 43% of the refractory follicular lymphoma patients and 33% of refractory diffuse large B-cell lymphoma patients in the phase 1b/2 study.
The antibody has an on-target anemia effect that occurs upon administration, but that was mitigated considerably by a priming and maintenance dosing approach, she added.
The study has demonstrated “excellent” response rates in a highly refractory patient population, said Caron A. Jacobson, MD, of Dana-Farber Cancer Institute and Harvard Medical School in Boston. “Targeting CD47 ... really helps to shift the balance from ‘don’t eat me’ to ‘eat me,’ ” Dr. Jacobson said at the meeting.
“Importantly, we saw very little toxicity in the study, with very few grade 4 adverse events and no immune-related adverse events,” she added.
Most adverse events were grade 1 or 2, with the most common being the expected on-target anemia associated with 5F9. Using an initial priming dose of 5F9 results in a “temporary and mild decline” in hemoglobin due to clearance of aged red blood cells, Dr. Advani said.