Digital droplet PCR evaluation of patient samples at remission and reactivation. (A) Representative plots of ddPCR performed on RT-qPCR–negative samples for patients 4 (left) and 3 (right), with wild-type (WT) droplets on the vertical axis and mutant BRAF V600E on the horizontal axis. Both still exhibit a small population of BRAF V600E–mutant alleles, as evidenced by small cluster of FAM-positive droplets. (B-C) ddPCR performed on bone marrow 14 months after discontinuation of dabrafenib in patient 4 (B) and peripheral blood at time of relapse in patient 3 (C). a.u., arbitrary units.