Immunotherapy resistance remains a challenge in immuno-oncology, and predictive biomarkers are needed to guide combination immunotherapy selection for the individual patient. We showed that elevated tumor-intrinsic NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) signaling activity correlates with checkpoint inhibitor resistance in several independent cohorts of stage III/IV melanoma and gastroesophageal (GE) adenocarcinoma. In situ hybridization demonstrated tumor NLRP3 copy number gain in immunotherapy-resistant melanomas and GE adenocarcinomas harboring enhanced NLRP3 signaling activity. Nlrp3 amplification suppressed NOD-, LRR-, and CARD-containing 5–mediated (NLRC5-mediated) MHC class I upregulation, while spatial transcriptomic analysis of patient-derived GE adenocarcinomas confirmed that NLRP3 signaling activity inversely correlated with NLRC5 and MHC class I–associated gene expression. Mechanistically, NLRP3 binds to and inhibits signal transducer and activator of transcription 1 (STAT1) dimerization, nuclear translocation, and NLRC5 transcription. Consistent with these findings, pharmacologic inhibition of the NLRP3 inflammasome augmented tumor STAT1/NLRC5 signaling, enhanced MHC class I surface expression, and overcame anti–programmed cell death 1 resistance in an orthotopic model of gastric adenocarcinoma. This work reveals a fundamental link between cellular stress and tumor-mediated immune evasion and indicates that the tumor NLRP3 signaling pathway merits further clinical study as a therapeutic target and a source of companion biomarkers for overcoming checkpoint inhibitor resistance in patients with cancer.
Balamayroon Theivanthiran, Nagendra Yarla, Kaylee Villarreal, Y-Van Nguyen, Mahere Rezazade Bazaz, Ernesto Pena Calderin, Linda Cao, Kyra Majors, Michael P. Plebanek, Alisha Holtzhausen, Emily Bolch, Douglas B. Johnson, Hope Uronis, John H. Strickler, Nicholas C. DeVito, Brent A. Hanks