Unfortunately, accumulating evidence suggests the predictive value of this biomarker may be limited (2), with recent analyses of TMB in mono- or combination CPI for non-small cell lung cancer (NSCLC) indicating an overall area under the receiver operator characteristic (ROC) curve (AUC) of 0.60 and 0.68, respectively, for predicting durable clinical benefit (3, 4), comparable to the accuracy of PD-L1 IHC, while results of Checkmate 026, a study of first-line Nivolumab for NSCLC, revealed no difference in overall survival in subjects stratified by TMB (5). The gene discussed is CD274; the disease is non-small cell lung carcinoma.