Study of GDC-0084 in Pediatric Patients With Newly Diagnosed Diffuse Intrinsic Pontine Glioma or Diffuse Midline Gliomas

Pediatric high-grade gliomas are highly aggressive and treatment options are limited. The purpose of this first-in-pediatrics study is to examine the safety, tolerability, and pharmacokinetics of GDC-0084 and to estimate its maximum tolerated dose (MTD) when administered to pediatric patients with diffuse intrinsic pontine glioma (DIPG) or other diffuse midline H3 K27M-mutant gliomas after they have received radiation therapy (RT). GDC-0084 is a brain-penetrant inhibitor of a growth-promoting cell signaling pathway that is dysregulated in the majority of diffuse midline glioma tumor cells. This study is also designed to enable a preliminary assessment of the antitumor activity of single-agent GDC-0084, in the hope of enabling rational combination therapy with systemic therapy and/or radiation therapy (RT) in this patient population, which is in desperate need of therapeutic advances. Primary Objectives 1. To estimate the maximum tolerated dose (MTD) and/or the recommended phase 2 dosage (RP2D) of GDC-0084 in pediatric patients with newly diagnosed diffuse midline glioma, including diffuse intrinsic pontine glioma (DIPG) 2. To define and describe the toxicities associated with administering GDC-0084 after radiation therapy (RT) in a pediatric population 3. To characterize the pharmacokinetics of GDC-0084 in a pediatric population Secondary Objectives 1. To estimate the rate and duration of radiographic response in patients with newly diagnosed DIPG or other diffuse midline glioma treated with RT followed by GDC-0084 2. To estimate the progression-free survival (PFS) and overall survival (OS) distributions for patients with newly diagnosed DIPG or other diffuse midline glioma treated with RT followed by GDC-0084