Taking a preventive medication to reduce bowel problems from cancer immunotherapy

This trial is testing whether mesalamine, an anti-inflammatory medication, can help prevent a common and sometimes serious side effect called immune-related colitis (severe diarrhea and bowel inflammation) that occurs in some patients receiving combination immunotherapy (ipilimumab and nivolumab) for advanced melanoma or rectal cancer. The medication is taken by mouth four times a day alongside standard cancer treatment. Researchers hope this preventive approach will keep patients more comfortable and allow them to continue their cancer therapy without interruption.

Combination immunotherapy is an effective treatment for advanced melanoma and rectal cancer, but it can cause severe diarrhea and bowel inflammation in many patients, sometimes forcing doctors to pause or stop treatment. This trial aims to see whether taking this medication in advance can reduce how often and how severe these bowel problems become, helping more patients tolerate their cancer treatment.