A Pilot Study Investigating Upfront Adaptive Immunotherapy Approach in Children, Adolescent and Young Adult (CAYA) Patients With Replication-Repair Deficient (RRD) High-Grade Gliomas (HGG)

This is open label, multicentre, single arm, pilot study of upfront nivolumab in patients with RRD-glioblastoma with favorable immune/genomic biomarkers. The purpose of the study is to use upfront immune checkpoint inhibitor (ICI) to delay/avoid radiation for patients with RRD-glioblastoma with favorable clinical (Gross total resection (GTR) or near total resection (NTR)) and biological (RRD, hypermutation, immune activation) biomarkers. At progression, patients will be undergoing surgery/biopsy and will get a combination of radiation + ICI followed by maintenance ICI. This model will allow us to additionally study the evolution tumor in response to ICI. The study will have two domains.