Measuring tumor mutation burden in cell-free DNA: advantages and limits

The treatment for advanced non-small cell lung cancer (NSCLC) has changed rapidly over the last several years. There are now several commercially available checkpoint inhibitors (CPI) targeting the programmed death ligand 1 (PD-L1)-programmed death 1 (PD-1) pathway. These CPIs have been shown to confer a significant overall survival (OS) benefit in first- and second-line therapy for unresectable/metastatic NSCLC (1-5). While the use of CPI in the clinic is prevalent, the determinants of those most likely to benefit remains imprecise.