Transcriptional phenocopies of deleterious KEAP1 mutations correlate with survival outcomes in lung cancer treated with immunotherapy

Purpose: Co-occurring mutations in KEAP1 and STK11/KRAS have emerged as determinants of survival outcomes in patients with non-small cell lung cancer (NSCLC) treated with immunotherapy. However, these mutational contexts identify a fraction of nonresponders to immune checkpoint inhibitors. We hypothesized that KEAP1 wild-type tumors recapitulate the transcriptional footprint of KEAP1 mutations and that this KEAPness phenotype can determine immune responsiveness with higher precision compared to mutation-based models. Experimental design: The Cancer Genome Atlas was used to infer the KEAPness phenotype and explore its immunological correlates at the pan-cancer level. The association between KEAPness and survival outcomes was tested in two independent cohorts of patients with advanced NSCLC treated with immunotherapy and profiled by RNA sequencing (SU2C n = 153; OAK/POPLAR n = 439). The NSCLC TRACERx421 multiregion sequencing study (tumor regions, n = 947) was used to investigate evolutionary trajectories. Results: KEAPness-dominant tumors represented 50% of all NSCLCs and were associated with shorter progression-free survival (PFS) and overall survival (OS) compared to KEAPness-free cases in independent cohorts of patients with NSCLC treated with immunotherapy (SU2C PFS P = 0.042, OS P = 0.008; OAK/POPLAR PFS P = 0.0014, OS P < 0.001). Patients with KEAPness tumors had survival outcomes comparable to those with KEAP1-mutant tumors. In the TRACERx421, KEAPness exhibited limited transcriptional intratumoral heterogeneity and immune exclusion, resembling the KEAP1-mutant disease. This phenotypic state occurred across genetically divergent tumors, exhibiting shared and private cancer genes under positive selection when compared to KEAP1-mutant tumors. Conclusions: We identified a KEAPness phenotype across evolutionary divergent tumors. KEAPness outperforms mutation-based classifiers as a biomarker of inferior survival outcomes in patients with NSCLC treated with immunotherapy.