Clinical and molecular features of acquired resistance to immunotherapy in non-small cell lung cancer
Although cancer immunotherapy with PD-(L)1 blockade is now routine treatment for patients with lung cancer, remarkably little is known about acquired resistance. We examined 1,201 patients with NSCLC treated with PD-(L)1 blockade to clinically characterize acquired resistance, finding it to be common (occurring in more than 60% of initial responders), with persistent but diminishing risk over time, and with distinct metastatic and survival patterns compared to primary resistance. To examine the molecular phenotype and potential mechanisms of acquired resistance, we performed whole transcriptome and exome tumor profiling in a subset of NSCLC patients (n=29) with acquired resistance. Systematic immunogenomic analysis revealed that tumors with acquired resistance differentially expressed features of inflammation and interferon (IFN) signalling. In particular, relapsed tumors could be separated into those with either upregulated or with stable expression of IFN? response genes. Tumors with upregulated IFN? response genes were associated with putative routes of resistance characterized by signatures of persistent IFN signaling, immune dysfunction, and mutations in antigen presentation genes. Transcriptomic profiling of cancer cells from multiple murine models of acquired resistance to PD-(L)1 blockade also showed evidence of high IFN-stimulated genes coupled to an altered or attenuated induced response after in vitro IFN? treatment. In summary, we characterized clinical and molecular features of acquired resistance to PD-(L)1 blockade in NSCLC and found evidence of ongoing but altered IFN response. The persistently inflamed, rather than excluded or deserted, tumor microenvironment of acquired resistance informs therapeutic strategies to effectively reprogram and reverse acquired resistance. Overall design: Bulk RNA-seq of parental, exposed to low-level chronic IFNG treatment, and ICB-relapsed LLC1 and KP mouse lung cancer tumors (CD45-); 3 biological replicates for each condition