This was a 4-part (Part A, Part B, Part C and Part D), Phase I/IIa, multi-center, open label, study in pediatric subjects with refractory or recurrent tumors.~Part A was a repeat dose, dose escalation and expansion phase that identified the recommended phase II dose (RP2D) of trametinib monotherapy using a 3 + 3 dose- escalation procedure. The starting dose level of trametinib was 0.0125 mg/kg/day, the second dose level was 0.025 mg/kg/day and the third dose level was 0.040 mg/kg/day. Additionally, in Part A extension an intermediate trametinib dose level of 0.032 mg/kg/day was assessed in subjects under 6 years of age. In all cohorts, the total daily trametinib dose was not to exceed the adult dose (2 mg) in any subject.~Part B evaluated the preliminary activity of trametinib monotherapy in 4 disease-specific cohorts of subjects:~B1: Refractory or relapsed neuroblastoma B2: Recurrent or unresectable low grade glioma (LGG) with BRAF tandem duplication with fusion (glioma fusion) B3: Neurofibromatosis Type -1 associated plexiform neurofibromas (NF-1 with PN) that are unresectable and medically significant B4: BRAF V600 mutant tumors In Part B it was used the RP2D of trametinib (0.025 mg/kg/day) determined in Part A.~Part C was a 3+3 study design to determine the safety, tolerability and preliminary activity of the RP2D of trametinib in combination with a limited dose escalation of dabrafenib. The trametinib dose administered in Part C was based on the trametinib monotherapy RP2D from Part A (0.025 mg/kg/day). For the evaluation of combination therapy in this study, the starting dose of dabrafenib was 50% of the monotherapy RP2D established in a separate study: 2.63 mg/kg/day (<12 years old subjects) and 2.25 mg/kg/day (≥12 years old subjects). The second dose level of dabrafenib was 100% of the monotherapy RP2D: 5.25 mg/kg/day (<12 years old subjects) and 4.5 mg/kg/day (≥12 years old subjects).~Additionally, in Part C extension, the trametinib dose determined from Part A extension (0.032 mg/kg/day) with 100% pediatric RP2D of dabrafenib (5.25 mg/kg/day) was assessed in subjects under 6 years of age.~In all cohorts, the total daily trametinib dose was not to exceed the adult dose (2 mg) in any subject and the total daily dabrafenib dose was not to exceed the adult dose (300 mg) in any subject.~Part D evaluated the preliminary activity of trametinib in combination with dabrafenib in two disease-specific cohorts of subjects diagnosed with low grade glioma (LGG) and Langerhans cell histiocytosis (LCH).~In Part D it was used the RP2D of the combination treatment determined in Part C (0.025 mg/kg/day trametinib and the 100% RP2D of dabrafenib) in subjects 6 years to < 18 years of age. Additionally, once Part C extension had defined the trametinib RP2D for subjects under 6 years of age, this dose was used for the remaining subjects enrolled in Part D (0.032 mg/kg/day trametinib and the 100% RP2D of dabrafenib).~The overall goal of this trial was to efficiently establish safe, pharmacologically relevant dose of trametinib monotherapy and trametinib in combination with dabrafenib in infants, children and adolescents and determine preliminary activity of trametinib monotherapy and trametinib in combination with dabrafenib in selected recurrent, refractory or unresectable childhood tumors.
This was a 4-part (Part A, Part B, Part C and Part D), Phase I/IIa, multi-center, open label, study in pediatric subjects with refractory or recurrent tumors.~Part A was a repeat dose, dose escalation and expansion phase that identified the recommended phase II dose (RP2D) of trametinib monotherapy. Part B evaluated the preliminary activity of trametinib monotherapy in 4 disease-specific cohorts of subjects. Part C was aimed to determine the safety, tolerability and preliminary activity of the RP2D of trametinib in combination with a limited dose escalation of dabrafenib. Part D evaluated the preliminary activity of trametinib in combination with dabrafenib in 2 disease-specific cohorts of subjects.~The overall goal of this trial was to efficiently establish safe, pharmacologically relevant dose of trametinib monotherapy and trametinib in combination with dabrafenib in infants, children and adolescents and determine preliminary activity of trametinib monotherapy and trametinib in combination with dabrafenib in selected recurrent, refractory or unresectable childhood tumors.