Treatment with ICB as monotherapy yields low durable responses; therefore, the rationale for combining ICB with next generation checkpoint molecules, cytokines, and/or cancer vaccines will likely become standard of care in several indications.34,35 The PD-1/PD-L1 axis is the most targeted pathway in cancer immunotherapy, with 4,400 trials opened since 2017. Here, PDCD1 is linked to cancer.