Prophylactic Mesalamine to Prevent Colitis Following Treatment With Ipilimumab/Nivolumab (Ipi/Nivo)

This study tests whether a drug called mesalamine (commonly used for inflammatory bowel disease) can prevent a bowel inflammation side effect called colitis that sometimes occurs when people with advanced melanoma receive a powerful combination immunotherapy (ipilimumab plus nivolumab). **You may be eligible if...** - You are 18 or older - You have been diagnosed with advanced (unresectable Stage III or IV) malignant melanoma - You are scheduled to receive ipilimumab and nivolumab (ipi/nivo) combination immunotherapy - You are in reasonably good health (ECOG 0–2) - If you could become pregnant, you have a negative pregnancy test and agree to use effective contraception **You may NOT be eligible if...** - You cannot give informed consent - You have a health condition that makes the study unsafe or impractical - You are pregnant or breastfeeding - You have known allergies to mesalamine or related compounds Talk to your doctor to see if this trial is right for you.