The Gut Microbiome and Immune Checkpoint Inhibitor Therapy in Solid Tumors

This observational study is collecting stool samples and data from cancer patients being treated with immune checkpoint inhibitors — a class of immunotherapy drugs — to understand how gut bacteria may influence how well the treatment works. **You may be eligible if...** - You are 18 or older - You have been diagnosed with non-small cell lung cancer, melanoma, triple-negative breast cancer, or kidney cancer (stages I–IV) - You are about to start treatment with a checkpoint inhibitor drug at a partner cancer center - You can speak English or Spanish and provide a stool sample **You may NOT be eligible if...** - You have active brain metastases - Your checkpoint inhibitor is being used off-label or through another clinical trial - You are participating in an immunotherapy clinical trial or pharma-sponsored observational study at the same time - You are pregnant - You are incarcerated Talk to your doctor to see if this trial is right for you.