Duration of exposure to study treatment and best overall response (investigator assessment) among patients with BRAF V600–mutant LCH. Duration of exposure to dabrafenib monotherapy (A) or dabrafenib plus trametinib (B) in pediatric patients with BRAF V600–mutant LCH; best overall response per investigator assessment using the Histiocyte Society response assessment guidelines. Categories of nonactive disease include CR, which indicates resolution of all disease signs or symptoms (no evidence of disease), and regressive disease, which indicates regressions of disease signs and symptoms with no new lesions. Categories of persistent active disease include SD, which indicates the persistence of signs and symptoms but no new lesions, and progressive disease, which indicates the progression of signs or symptoms and/or the appearance of new lesions. ^aindicates patients who have continued therapy on a rollover study, and ^bindicates that 2 patients did not have any postbaseline assessment because of early discontinuation and were considered to be nonresponders. REG, regressive disease.