Additionally, correlative science data from a phase I/II trial of cetuximab in combination with pembrolizumab demonstrated an increase in intratumoral CD3+ CD8+ cytotoxic T cells, a decrease in cytotoxic T cells in the peripheral blood, and decreased levels of PD1+ cytotoxic T cells in both the tumor and peripheral blood, consistent with therapy-related changes in the tumor microenvironment (185). The gene discussed is PDCD1; the disease is neoplasm.