FMT in Checkpoint Inhibitor-mediated Diarrhea and Colitis

This study tests whether a fecal microbiota transplant (FMT) — transferring healthy gut bacteria from a donor — can treat severe diarrhea and bowel inflammation caused by immunotherapy drugs used to treat cancer. This side effect, called immune checkpoint inhibitor colitis, can be debilitating. **You may be eligible if...** - You are 18 or older - You have melanoma or kidney cancer treated with immune checkpoint inhibitors (such as nivolumab, pembrolizumab, or ipilimumab) - You have developed grade 2–4 diarrhea or colitis as a side effect of immunotherapy **You may NOT be eligible if...** - You have other causes of diarrhea (like infection) - You have severe immune suppression from other causes - You are on antibiotics that would interfere with the transplant Talk to your doctor to see if this trial is right for you.