PDCD1 and leukemia: Furthermore, while upregulation of PD-1 and LAG-3 was observed on the majority of dysfunctional TCRTg101, combined PD-1 and LAG-3 blockade therapy did little to enhance effector cytokine production or control disease progression, which was somewhat surprising given the maintained expression of TCF1 in a significant proportion of TCRTg101 in the leukemia environment (Figures 3G, 3K, and 3L).