University of Texas M. D. Anderson Cancer Center researchers recently find that how well people with melanoma respond to treatment is linked with the composition of intestine microflora. They examined a total of 113 fecal samples from patients whose melanoma had spread, discovering that patients who benefited from anti-PD1 immunotherapy harbored a higher diversity of intestine microflora. They also identified a species of bacteria that was more abundant in these patients.
PD1, or called Programmed cell death protein 1 and CD279, is a cell surface receptor protein that in humans is encoded by the PDCD1 gene. The protein belongs to the immunoglobulin superfamily and is expressed on T cells and pro-B cells. PD1 functions as an immune checkpoint to regulate immune system, reduce antoimmunity, and promote self-tolerance. PD1 and its ligand PD1-L1 have been implicated in tumors escaping immune destruction. Anti-PD1 drugs use antibody to inhibit the PD1 and D1-L1. The emergence of anti-PD1 immunotherapy has profoundly modified therapeutic strategies in oncology.
Although it is known that there is a link between the microbiome, immune response, and solid tumors, this study provides the first evidence about the connection between the microbiome and patients’ response to immunotherapy. Using a technology called 16S rRNA sequencing, the team investigated the oral and gut microbes in 228 patients with metastatic melanoma, 93 of whom received anti-PD1 therapy. By analyzing patient fecal samples, the researchers identified a higher diversity of bacteria in patients who responded to the therapy, and these patients had larger amounts of Clostridiales. In contrast, patients who did not benefit from the treatment had more Bacteriodales.
The study was presented at the ASCO-Society for Immunotherapy in Cancer meeting in Orlando, and it demonstrates that examining diversity and composition of the microbiome is an approach of predicting immunotherapy response and modifying intestine microflora could promote treatment efficacy. (Cusabio offers various antibodies and proteins.)