Abstract 7479: Targeting the lipid kinase PIKfyve upregulates surface expression of MHC class I to augment cancer immunotherapy

Abstract

Abstract The widespread success of cancer immunotherapies suggests a promising future - but has been subverted by unresponsiveness and resistance. Current research has furthered the understanding of immunotherapy resistance through the findings of “hot” (responsive) and “cold” (unresponsive) tumors. Here, we focus on the genetic and pharmacological inhibition of PIKfyve, a lipid kinase regulator of autophagic flux and lysosomal biogenesis. We find that inhibition of PIKfyve results in the upregulation of major histocompatibility complex class I (MHC-I) surface expression in cancer cells (through inhibition of autophagic flux), resulting in increased CD8+ T cell-mediated cancer cell death. These findings were corroborated in multiple syngeneic mouse models, which also displayed increased intratumoral functional CD8+ T cells. In addition, the Pikfyve-depletion antitumor responses are CD8+ T cell and MHC-I dependent - as CD8+ T cell and B2m knockout rescued tumor growth - resulting in improved response to immune checkpoint blockable (ICB), adoptive cell therapy, and a therapeutic vaccine. Further, high PIKfyve expression predicts poor ICB response and is prognostic of poor survival in ICB-treated cohorts. Ultimately, these findings collectively suggest PIKfyve as an effective target to enhance immunotherapies through elevation of MHC-I surface expression in cancer cells, and accordingly, PIKfyve inhibitors have novel potential to increase immunotherapy response in cancer patients. Citation Format: Parth Borker, Yi Bao, Yuanyuan Qiao, Arul Chinnaiyan, Jae Eun Choi, Yuping Zhang, Rahul Mannan, Caleb Cheng, Tongchen He, Yang Zheng, Jiali Yu, Mahnoor Gondal, Gabriel Cruz, Sara Sara Grove, Xuhong Cao, Fengyun Su, Rui Wang, Yu Chang, Ilona Kryczek, Marcin Cieslik, Michael D. Green, Weiping Zou. Targeting the lipid kinase PIKfyve upregulates surface expression of MHC class I to augment cancer immunotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7479.