LAUSR

25Background: Somatic tumor mutational burden (TMB) and a T-cell inflamed gene expression profile (GEP) predict response to anti-PD-1/PD-L1 immunotherapies in multiple tumor types. We assessed the potential for GEP and TMB to jointly predict clinical response to pembrolizumab and to identify distinct, targetable patterns of biology that may modulate response/resistance. Methods: To assess the individual and joint clinical utility of TMB and GEP in a pan-tumor context, pembrolizumab-treated patients with advanced solid tumors and melanoma were stratified as 4 biomarker-defined clinical response groups (GEP low/TMB low, GEP low/TMB high, GEP high/TMB low, GEP high/TMB high; N > 300) based on cutoffs for TMB (ROC Youden Index associated) and GEP (selected via analysis of pan cancer data). TMB and GEP were used to guide transcriptome and exome analysis of tumors in 2 large databases (Moffitt, n = 2944; TCGA, n = 6978). Results: TMB and GEP had a low, but significant, correlation in these clinical datasets. OR...