A Study to Determine Safety, Tolerability and Pharmacokinetics of Oral Dabrafenib In Children and Adolescent Subjects

Part 1 was a dose escalation study in subjects with any BRAF V600 mutation-positive solid tumor, designed to optimize efficiency of enrollment, minimize the number of subjects being treated at potentially sub-efficacious dose levels, and incorporating the evolving pharmacokinetic, safety and efficacy data from the adult development program. Dose escalation part of the study was to determine the maximum tolerated dose (MTD) and recommend the dose for phase 2 studies (RP2D). An MTD has not been identified for dabrafenib in the adult population. This does not preclude the identification of an MTD in the pediatric population. Modified RSD was employed to determine the MTD. Part 1 used dual criteria of dose limiting toxicity (DLT) and observed dabrafenib exposures to make decisions to advance to the next dose level. Target exposure criteria based on adults treated at the approved adult dose of 300 mg (150 mg given BID) were observed in this study before meeting criteria for stopping dose escalation due to observations of DLTs, and served as the criteria for determining the RP2D for dabrafenib in pediatric subjects. Thus, MTD has not been established in pediatric population, similar to the previous dose finding efforts in adult subjects. Part 2 was a tumor specific expansion study to further evaluate the safety/tolerability profile and to discover possible clinical efficacy of dabrafenib in 4 tumor-specific pediatric populations known to have BRAFV600 activation: high grade glioma (HGG), low grade glioma (LGG), Langerhans cell histiocytosis (LCH), miscellaneous tumors including melanoma and papillary thyroid carcinoma (Other). The exposures for subjects dosed on the basis of weight were also evaluated by age categories.