Another study on murine model found that co-expression of PD-1 and Tim-3 on CD8+ T cells increased during AML progression, and instead of blocking single pathway, combined PD-1/PD-L1 and Tim-3/galectin-9 blockade led to the reduction of tumor burden and lethality (Zhou et al., 2011). Here, PDCD1 is linked to acute myeloid leukemia.