Despite the overall increase in T cells in sensitive tumors, the TME of resistant tumors were found to possess an increase in effector CD8 cells, however, these T cells exhibited increased exhaustion as assessed by the transcriptional expression of Pdcd1, Cd27, and Lag3. Increased levels of these genes has been previously linked to decreased effector function and failure to eliminate cancer cells (55). Here, PDCD1 is linked to cancer.