Fecal Microbiota Transplantation in Treating Immune-Checkpoint Inhibitor Induced-Diarrhea or Colitis in Genitourinary Cancer Patients

This study investigates whether transplanting healthy gut bacteria from a donor (called fecal microbiota transplant or FMT) can help patients whose immune systems have been severely damaged by immunotherapy (checkpoint inhibitor) drugs used to treat cancer. These immune-related side effects can be life-threatening. **You may be eligible if...** - You received immunotherapy (immune checkpoint inhibitor drugs) for cancer - You developed serious immune-related side effects, such as severe colitis (gut inflammation), that are not responding to steroid treatment - You are 18 or older **You may NOT be eligible if...** - You have active infections that could be worsened by the procedure - You are severely immunocompromised beyond what is expected from your treatment - You have certain bowel conditions that make the procedure unsafe Talk to your doctor to see if this trial is right for you.