Lung Cancer with a High Tumor Mutational Burden

To the Editor: Hellmann and colleagues (May 31 issue) 1 found that tumor mutation burden assessed with the commercial assay FoundationOne CDx helped to predict the response to immune checkpoint inhibitor therapy in patients with non–small-cell lung cancer (NSCLC), irrespective of programmed death ligand 1 (PD-L1) expression. Guidelines regarding turnaround times for tests to detect predictive genomic alterations (e.g., EGFR , ALK , ROS1 , and BRAF V600E) and immune biomarkers such as PD-L1 immunohistochemical findings recommend targets of 3 workdays from a request for testing to receipt by a reference laboratory and testing results within 10 workdays. 2-4 This workflow is currently acceptable to . . .