Cancer patients suffering from renal cell carcinoma (RCC) and non-small-cell lung cancer (NSCLC) treated with antiprogrammed cell death ligand-1 (PD-L1) or PD-L1 plus CTLA-4 mAb monotherapy who were also undergoing treatment with antibiotics (β-lactam or quinolones for pneumonia or urinary tract infections) in the beginning were examined for thirty days for gut microbiota diversity and composition leading to dysbiosis. Here, CTLA4 is linked to renal cell carcinoma.