Bafetinib enhances anti-tumor immunity by activating the NLRP3 inflammasome in macrophage

Insufficient lymphocyte infiltration in the tumor microenvironment is a major cause of resistance to immunotherapy. Previous studies have indicated that NLRP3 inflammasome activation is crucial for lymphocyte infiltration and activation, but safe, effective, and specific NLRP3 inflammasome agonists are still lacking. Here, we identified a clinical phase II drug, bafetinib, that specifically activates the NLRP3 inflammasome through high-throughput drug screening. Bafetinib directly targets and binds to the potassium channel KCNK6/TWIK2, blocking its degradation via the chaperone-mediated autophagy (CMA) pathway to promote potassium efflux, thereby triggering NLRP3 inflammasome activation. Furthermore, we developed a hypoxia-responsive nanoparticle platform capable of targeted delivery of bafetinib (Baf@NPs) to tumors and specific release in the tumor microenvironment. Baf@NPs treatment significantly represses tumor growth and enhances anti-tumor immunity by triggering NLRP3 inflammasome in macrophage. Moreover, the combination of Baf@NPs with PDCD1/PD-1 antibodies further enhanced anti-tumor immunity and improved tumor treatment. Together, our results identify a safe, highly effective and specific NLRP3 inflammasome agonist and underscore it enhances anti-tumor immunity by triggering the NLRP3 inflammasome in macrophages, providing a potential therapeutic strategy for tumor treatment. Abbreviation: 3-MA: 3-methyladenine; BMDMs: bone marrow-derived macrophage; CMA: chaperone-mediated autophagy; CHX: cycloheximide; CQ: chloroquine; Co-IP: co-immunoprecipitation; DAPI: 4’,6-diamidino-2-phenylindole; TNF/TNF-α: tumor necrosis factor; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; IL1B/IL-1β: interleukin 1 beta; IL6: interleukin 6; KFERQ: lysine-phenylalanine-glutamate-arginine-glutamine; LAMP2A: lysosomal associated membrane protein 2A; LPS: lipopolysaccharide; MG132: carbobenzoxy-L-leucyl-L-leucyl-L-leucinal; NLRP3: NLR family pyrin domain containing 3; siRNAs: small interfering RNAs; WT: wild-type.