Abstract 3537: Pharmacologic inhibition of the glycolytic pathway improves response to immune checkpoint blockade

Abstract Preferential engagement in glycolysis is a hallmark of cancer cells and contributes to the progression and metastasis of many tumor types, including melanoma and triple-negative breast cancer (TNBC). Tumor reliance on glycolysis is emerging as a mechanism of resistance to immunotherapy, due in part to lactate-mediated immunosuppression and competition for glucose between effector T cells and tumor cells within the tumor microenvironment. Elevated serum lactate dehydrogenase (LDH) levels are associated with poor outcomes in cancer patients, and we observed that serum lactate and LDH levels correlate with primary tumor burden in mice. We recently demonstrated that genetic dampening of LDH subunit A in 4T1 TNBC results in improved and long-lasting anti-tumor responses to CTLA-4 blockade in mice. Therefore, we hypothesize that combining LDH inhibitors (LDHi) with CTLA-4 blockade will be an effective strategy to combat resistance to anti-CTLA-4 therapy. Since activated T cells rely on glycolysis, we first determined that glycolytic cancers overexpress LDH (compared with immune cells) by analyzing single-cell transcripts from patient melanoma biopsies. LDHA gene expression is significantly higher in malignant cells than infiltrating CD8+ T cells, and we replicated these findings at the protein level in whole cell lysate from B16-F10 melanoma and 4T1 TNBC tumor cells and tumor-antigen specific T cells in vitro. We show that LDHi reduces tumor lactate production and glucose consumption without inhibiting anti-tumor T-cell killing in vitro. The anti-tumor effect of LDH inhibition requires adaptive immunity, as daily treatment with LDHi results in reduced tumor burden in immunocompetent but not immune-deficient mice. Finally, we show that targeting LDH in combination with CTLA-4 blockade is more effective in slowing B16-F10 growth compared with CTLA-4 blockade alone, and that this combination promotes effector T cell activation while destabilizing regulatory T cell function. Citation Format: Svena Verma, Inna Serganova, Sadna Budhu, Lauren Dong, Myat Ko, Levi Mangarin, Taha Merghoub, Jedd Wolchok, Roberta Zappasodi. Pharmacologic inhibition of the glycolytic pathway improves response to immune checkpoint blockade [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3537.