A Trial of Dabrafenib, Trametinib and Hydroxychloroquine for Patients With Recurrent LGG or HGG With a BRAF Aberration

In this phase I/II study, the investigators will investigate the safety and efficacy of dabrafenib + trametinib + HCQ (D+T+HCQ) and trametinib + HCQ (T+HCQ) in pediatric and young adult patients with BRAF-altered or NF1-associated gliomas who have previously received a RAF and/or MEK inhibitor. The goal of this study is to optimize the clinical effect of dabrafenib and trametinib by addressing intrinsic and acquired resistance that is well-described in V600E-mutant melanoma and for which there is preclinical and clinical evidence in pediatric gliomas. Aside from overlapping skin toxicity of dabrafenib and trametinib, which preliminarily does not appear worse in the D+T combination in adults and children, potential for ocular toxicity, which has been observed with each agent as monotherapy, will require close monitoring. An important outcome of this study will be improved understanding of resistance mechanisms and the role of autophagy in BRAF-altered or NF1-associated gliomas through sequencing of pre- and post-RAFi or MEKi tumor (when available) and measurement of autophagy inhibition in throughout protocol therapy. Phase I: The primary objective of the Phase I component is to estimate the maximum tolerated doses (MTD) and recommended Phase II doses (RP2D) of D+T+HCQ and T+HCQ in children and young adults with recurrent or progressive glioma treated with prior RAF and/or MEK inhibitor therapy. Patients with BRAF V600E LGG or HGG will receive the combination of D+T+HCQ given orally in the form of capsules which must be taken whole, or an oral solution made from tablets. Hydroxychloroquine will only be administered by oral suspension. Within each combination, Dabrafenib and Hydroxychloroquine will be administered twice a day in a 28-day course. Trametinib will be administered once a day for 28 days during each course. One course is equivalent to 28 days. Therapy with either combination may continue for up to 2 years (26 courses) in the absence of disease progression or unacceptable toxicity. Phase II Potential patients for the Phase II portion of the trial must provide magnetic resonance imaging studies for central review for screening prior to enrollment: (1) prior targeted MEK/RAF therapy baseline, (2) prior MEK/RAF therapy best response, (3) scan at off treatment, and if different from off treatment (4) scan documenting PD associated with prior MEK/RAF targeted therapy. Additional scans may be requested from the site if the required eligibility assessments cannot be completed based on these minimal imaging requirements. In the Phase II portion of the trial, patients will continue to receive either the D +T+HCQ or T+HCQ combination at the RP2D defined in the Phase I portion. All drugs will be given continuously without a break unless required for excess toxicity. For Phase I subjects who are treated at the MTD a similar review will take place retrospectively to determine whether the patients meet the criteria to be included in the Phase II cohort.