Digital detection of T790M—yes or no to an ultrasensitive assay

In the management of advanced non-small cell lung cancer it is now routine clinical practice to screen diagnostic specimens for activating mutations in epidermal growth factor receptor (EGFR) and KRAS and translocations involving ALK and ROS. When detected, these mutations directly inform clinical decision-making. In particular, patients with one of the common EGFR mutations, exon 19 deletion or L858R, often respond extremely well to EGFR tyrosine kinases inhibitors (TKIs). However, almost inevitably patients will relapse and the most common mechanism of resistance is a secondary mutation in EGFR that alters the affinity of the binding pocket to ATP—the T790M mutation (1).