A Study of JNJ-89402638 for Metastatic Colorectal and Gastric Cancers

This study is testing a new experimental drug called JNJ-89402638, alone or in combination with other cancer therapies, in people with advanced colorectal cancer (cancer of the colon or rectum) or gastric cancer (stomach or stomach-esophagus junction cancer) that has spread and progressed on prior treatments. **You may be eligible if...** - You are 18 or older - You have colorectal cancer that has spread and progressed after at least 1-2 prior lines of standard treatment (the specific number depends on which study arm you qualify for) - OR you have gastric or stomach-junction cancer that has progressed after at least 1 prior line of treatment - You have at least one measurable tumor on scans - Your general health and organ function are adequate **You may NOT be eligible if...** - Your cancer has not spread to distant sites or is eligible for surgery - You have certain genetic profiles that direct you to other treatments - You have serious heart, liver, kidney, or other health conditions that make experimental treatment unsafe - You have active brain metastases - You have previously received this specific drug Talk to your doctor to see if this trial is right for you.