Originally published by our sister publication Pharmacy Practice News
Fecal microbiota transplantation (FMT) may enhance the effectiveness of immunotherapies by reducing gut dysbiosis, according to a presentation at the 2025 ASCO Annual Meeting.
However, antibiotics should be used sparingly in people receiving immunotherapies, in short stints after an infection, because the overuse of antibiotics may increase dysbiosis and could potentially inhibit the effectiveness of FMT, according to Arielle Elkrief, MD, FRCPC, the co-director of the CHUM Microbiome Centre, in Montreal. “Dysbiosis is a key biomarker of response and resistance to immunotherapy; the goal of FMT is to replace the diseased dysbiotic microbiome of a patient with that of a donor microbiome,” Dr. Elkrief said.
She added that the FMT procedure does not generally require antibiotics, but short courses of antibiotics may be needed if FMT causes an infection.
“Fecal microbiota transplantation is safe and potentially increases immunotherapy activity across multiple histologies,” Dr. Elkrief said. In two phase 1 studies, an FMT donation from people who had benefited from immunotherapy helped melanoma patients who were refractory to immunotherapy, with post-FMT objective response rates (ORRs) of 20% to 30% (Science 2021;371[6529]:595-602 and 602-609).
These results prompted the phase 2 FMT-LUMINate trial, for which Dr. Elkrief is an investigator. This effort showed ORRs for FMT of, respectively, 80% in people with non-small cell lung cancer and 75% in those with melanoma (Cancer Res 2024;84 [7 suppl]:CT258).
FMT is not readily available, Dr. Elkrief noted, due to challenges with getting enough donors of fecal material. In her lab and others, researchers are developing live biotherapeutic products that mimic the action of FMT.
Given FMT’s limited availability, some patients taking immunotherapies won’t be able to benefit from it. However, many people taking immunotherapies will have access to antibiotics, which can be vital after infections—but it’s important not to overuse antibiotics in this situation, Dr. Elkrief stressed.
“Antibiotic stewardship is key to decreasing antibiotic-related dysbiosis and improving outcomes to immunotherapy for patients with cancer,” Dr. Elkrief said. When infections occur, she said, “we recommend a short course, a narrow spectrum and to reassess the need for antibiotics constantly” in consultation with experts in infectious disease.
Dr. Elkrief reported financial relationships with AstraZeneca, Bristol Myers Squibb and Merck.