Gut microbiome manipulation for cancer
Dr. Wargo’s research at MD Anderson has focused on metastatic breast cancer and immunotherapeutic checkpoint blockade. By sequencing microbiota samples and performing immune profiling in hundreds of patients, her team found that responders to PD-1 blockage have a greater diversity of gut bacteria and that “favorable signatures in the gut microbiome” are associated with enhanced immune responses in the tumor microenvironment.
Studies published last year in Science from investigators in Israel (2021 Feb 5;371[6529]:602-9) and Pittsburgh (2021 Feb 5;371[6529]:595-602), demonstrated that FMT promotes response in immunotherapy-refractory melanoma patients. In one study, FMT provided clinical benefit in 6 of 15 patients whose cancer had progressed on prior anti-PD-1 therapy, “which is pretty remarkable,” Dr. Wargo said.
Both research groups, she noted, saw favorable changes in the gut microbiome and immune cell infiltrates both at the level of the colon and the tumor.
Current research on FMT and other microbiome modulation strategies for cancer is guided in part by knowledge that tumors have microbial signatures – these signatures are now being identified across all tumor types – and by findings of “cross talk” between the gut and tumor microbiomes, she explained.
“Researchers are working hard to identify optimal consortia to enhance immune responses in the cancer setting, with promising work in preclinical models,” she said, and clinical trials are in progress. The role of diet in modulating the microbiome and enhancing anti-tumor immunity, with a focus on high dietary fiber intake, is also being investigated, she said.
Dr. Wargo reported that she serves on the advisory boards and is a paid speaker of numerous pharmaceutical and biotechnology companies, and is the coinventor of a patent submitted by the Texas MD Anderson Cancer Center on modulating the microbiome to enhance response to checkpoint blockade, and another related patent. Dr. Khanna reported that he is involved in research with Ferring/Rebiotix, Finch, Seres, Pfizer and Vendata, and does consulting for Immuron and several other companies. Dr. Kelly said she serves as an unpaid adviser for OpenBiome, a nonprofit stool bank, and that her site has enrolled patients in two of the trials testing products for CDI.