Summary Combination immune checkpoint blockade has demonstrated promising benefit in lung cancer, but predictors of response to combination therapy are unknown. Using whole exome sequencing to examine non-small cell lung cancer (NSCLC) treated with PD-1 plus CTLA-4 blockade, we found that high tumor mutation burden (TMB) predicted improved objective response, durable benefit, and progression-free survival. TMB was independent of PD-L1 expression and the strongest feature associated with efficacy in multivariable analysis. The low response rate in TMB low NSCLCs demonstrates that combination immunotherapy does not overcome the negative predictive impact of low TMB. This study demonstrates the association between TMB and benefit to combination immunotherapy in NSCLC. TMB should be incorporated in future trials examining PD-(L)1 with CTLA-4 blockade in NSCLC.

Tumor mutation burden (TMB) is a biomarker of response to immune checkpoint blockade (ICB). The impact of TMB on outcomes with targeted therapies has not been explored. We identified all patients with metastatic exon19del or L858R-mutant lung cancers treated with first/second-generation EGFR tyrosine kinase inhibitors (TKIs) with pretreatment next-generation sequencing data (MSK-IMPACT assay). The effect of TMB on time-to-treatment discontinuation (TTD) and overall survival (OS) were evaluated in univariate and multivariate analyses. wild-type lung adenocarcinoma samples were used for comparison. Among 153 patients with -mutant lung cancer, TMB was lower compared with EGFR wild-type ( = 1,849; median 3.77 vs. 6.12 mutations/Mb; < 0.0001) with a broad range (0.82-17.9 mutations/Mb). Patients with -mutant lung cancer whose tumors had TMB in the high tertile had shorter TTD (HR, 0.46; = 0.0008) and OS (HR, 0.40; = 0.006) compared with patients with low/intermediate TMB. Evaluating by median TMB, there was significantly shorter TTD and OS for patients with higher TMB (TTD, = 0.006; OS, = 0.03). In multivariate analysis, TTD and OS remained significantly longer in the low/intermediate tertile compared with high TMB (HR = 0.57, = 0.01; HR = 0.50, = 0.02, respectively). In paired pretreatment and postprogression samples, TMB was increased at resistance (median 3.42 vs. 6.56 mutations/Mb; = 0.008). TMB is negatively associated with clinical outcomes in metastatic patients with mutant lung cancer treated with EGFR-TKI. This relationship contrasts with that seen in lung cancers treated with immunotherapy.

Introduction: EGFR-mutant lung cancers are clinically and genomically heterogeneous with concurrent RB transcriptional corepressor 1 (RB1)/tumor protein p53 (TP53) alterations identifying a subset at increased risk for small cell transformation. The genomic alterations that induce lineage plasticity are unknown. Methods: Patients with EGFR/RB1/TP53-mutant lung cancers, identified by next-generation sequencing from 2014 to 2018, were compared to patients with untreated,

Purpose: Treatment with PD-(L)1 blockade can produce remarkably durable responses in nonsmall cell lung cancer (NSCLC) patients. However, a significant fraction of long-term responders ultimately progress and predictors of late progression are unknown. We hypothesized that circulating tumor DNA (ctDNA) analysis of long-term responders to PD-(L)1 blockade may differentiate those who will achieve ongoing benefit from those at risk of eventual progression. Experimental Design: In patients with advanced NSCLC achieving long-term benefit from PD-(L)1 blockade (PFS≥12 months), plasma was collected at a surveillance timepoint late during/after treatment to interrogate ctDNA by Cancer Personalized Profiling by Deep Sequencing (CAPP-Seq). Tumor tissue was available for 24 patients and was profiled by wholeexome sequencing (n=18) or by targeted sequencing (n=6).Results: 31 NSCLC patients with long-term benefit to PD-(L)1 blockade were identified and ctDNA was analyzed in surveillance blood samples collected at a median of 26.7 months after initiation of therapy. Nine patients also had baseline plasma samples available, and all had detectable ctDNA prior to therapy initiation. At the surveillance timepoint, 27 patients had undetectable ctDNA and 25 (93%) have remained progression-free; by contrast, all four patients with detectable ctDNA eventually progressed (Fisher's p<0.0001; PPV 1 [95% CI 0.51-1]; NPV 0.93 [95% CI 0.80-0.99]).Conclusions: ctDNA analysis can noninvasively identify minimal residual disease in patients with long-term responses to PD-(L)1 and predict the risk of eventual progression. If validated, ctDNA surveillance may facilitate personalization of the duration of immune checkpoint blockade and enable early intervention in patients at high risk for progression.

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