The Use of Fecal Microbiota Transplant in Overcoming and Modulating Resistance to Anti-PD-1 Therapy in Patients with Skin Cancer.

While immune checkpoint inhibitors have evolved into the standard of care for advanced melanoma, 40-50% of melanoma cases progress while on therapies. The relationship between bacterium and carcinogenesis is well founded, such as in in gastric cancers, and in colorectal cancers. This interplay between dysbiosis and carcinogenesis questions whether changes in the microbiome could affect treatment. Thus, FMT may find utility in modifying the efficacy of anti-PD-1. This review aims to examine the use of FMT in treatment-resistant melanoma. A literature search was performed using the keywords "fecal microbiota transplant" and "skin cancer". Studies were reviewed for inclusion criteria and quality and in the final stage, and three studies were included. Overall objective responses were reported in 65% of patients who were able to achieve CR, and 45% who achieved PR. Clinical benefit rate of combined CR/PR with stable disease greater or equal to 6 months was 75%. Reported objective responses found durable stable disease lasting 12 months. Overall survival was 7 months, and overall PRS was 3 months. As for the evaluation of safety, many patients reported grade 1-2 FMT related AE. Only following the administration of anti-PD-1 therapy were there a grade 3 or higher AE.