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Abstract 5635: Combined MEK and mitophagy inhibition promotes mtDNA-mediated innate immunity in KRAS-mutant cancer


 Although mitochondrial DNA (mtDNA) can stimulate innate immune response that potentiates the efficacy of cancer immunotherapy, how to maximize this innate immune system in certain cancer subtypes remains unknown. Here we show that mtDNA is enriched in KRAS-mutant tumor where the dsDNA-sensor machinery cGAS-STING signaling is autonomously activated at the baseline. Intriguingly, MEK inhibitor induces cytosolic mtDNA release to potently activate cGAS-STING pathway, that is counteracted by PRKN-mediated mitophagy to eliminate mtDNA within damaged mitochondria in KRAS-mutant tumor. Combined MEK and mitophagy inhibitors synergistically boost type I IFNs through mitochondrial stress and promote lymphocyte infiltration into the TME in a mtDNA efflux-dependent manner. Moreover, this combination enhances the efficacy of PD-1 blockade in KRAS-mutant tumor. PRKN clinically associates with KRAS/LKB1-mutant subtype, lower antigen-presenting signature, and ICB resistance. Together, targeting mtDNA renders promising strategy to enable cancer immunotherapy in KRAS-mutant cancers.
 Citation Format: Kosuke Tanaka, Tomoko Yamamori Morita, Yumi Hakozaki, Miyuki Yoshiya, Chiaki Mashima, Jie Liu, Shun-ichiro Kageyama, Akihiro Ohashi, Susumu Kobayashi. Combined MEK and mitophagy inhibition promotes mtDNA-mediated innate immunity in KRAS-mutant cancer [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 5635.