Oncogene induced TIM-3 ligand expression dictates susceptibility to anti-TIM-3 therapy in mice.

Leukemia relapse is a major cause of death after allogeneic hematopoietic cell transplantation (allo-HCT). We tested the potential of targeting TIM-3 for improving graft-versus-leukemia (GVL) effects. We observed differential expression of TIM-3 ligands when hematopoietic stem cells overexpressed certain oncogenic-driver mutations. Anti-TIM-3 Ab-treatment improved survival of mice bearing leukemia with oncogene-induced TIM-3 ligand expression. Conversely, leukemia cells with low ligand expression were anti-TIM-3 treatment-resistant. In vitro, TIM-3 blockade or genetic deletion in CD8+ T cells (Tc) enhanced Tc activation, proliferation and IFN-γ production while enhancing GVL effects, preventing Tc exhaustion and improving Tc cytotoxicity and glycolysis in vivo. Conversely, TIM-3 deletion in myeloid cells did not affect allogeneic Tc proliferation and activation in vitro, suggesting that anti-TIM-3-treatment-mediated GVL effects are Tc-induced. In contrast to anti-PD-1 and anti-CTLA-4-treatment, anti-TIM-3-treatment did not enhance acute graft-versus-host-disease (aGVHD). TIM-3 and its ligands were frequently expressed in acute myeloid leukemia (AML) cells of patients with post-allo-HCT relapse. We deciphered the connection between oncogenic mutations found in AML and TIM-3 ligands expression and identify anti-TIM-3-treatment as a strategy to enhance GVL effects via metabolic and transcriptional Tc-reprogramming, without exacerbation of aGVHD. Our findings support clinical testing of anti-TIM-3 Abs in patients with AML relapse post-allo-HCT.