Fecal Microbiota Transplant and Re-introduction of Anti-PD-1 Therapy (Pembrolizumab or Nivolumab) for the Treatment of Metastatic Colorectal Cancer in Anti-PD-1 Non-responders

This phase II trial studies the effect of fecal microbiota transplant and re-introduction of anti-PD-1 therapy (pembrolizumab or nivolumab) in treating anti-PD-1 non-responders with colorectal cancer that has spread to other places in the body (metastatic). Fecal microbiota transplants contain the normal bacteria and viruses found in fecal (stool) material. Immunotherapy with monoclonal antibodies, such as pembrolizumab and nivolumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Giving pembrolizumab or nivolumab with fecal microbiota transplants may help to control the disease.