Previous studies have shown that combination therapy with PD-1/PD-L1 and CTLA-4 inhibitors can induce deeper tumor responses in some patients, but it is also associated with substantially higher rates of severe adverse events, immune-related toxicities, and treatment discontinuation compared with PD-1/PD-L1 monotherapy (37, 38). This evidence concerns the gene PDCD1 and neoplasm.