TRAIL-armed CAR T cells in combination with ONC206 for diffuse midline gliomas

Objective

Diffuse midline gliomas (DMG), including diffuse intrinsic pontine glioma (DIPG), are fatal pediatric brain tumors with median survival under 12 months, and current therapy is limited to palliative radiotherapy. Chimeric antigen receptor (CAR) T cells are a promising immunotherapy, but responses in DMG remain incomplete due to blood-brain barrier (BBB) restriction and an immunosuppressive tumor microenvironment (TME). At Seattle Children’s Hospital, I contributed to the development of B7-H3 CAR T cells in the BrainChild-03 trial (NCT04185038), which showed tolerability in children but highlighted the urgent need for combinatorial approaches. ONC206, an imipridone tested in the PNOC-023 trial (NCT04732065), crosses the BBB and primes DMG cells for apoptosis by disrupting mitochondrial respiration and upregulating death receptor 5 (DR5). B7-H3 CAR T cells combined with ONC206 improved efficacy but underscored the need for additional synergistic strategies. TRAIL, the natural ligand of DR5, induces apoptosis and can reprogram macrophages toward an anti-tumor phenotype. However, its poor stability and pharmacokinetics limit systemic delivery. To address these barriers, ONCAR-TRAIL combines local TRAIL delivery with ONC206 and aims to: 1. develop and test TRAIL-expressing B7-H3 CAR T cells in patient-derived models and orthotopic xenografts, with an inducible GD2-SynNotch circuit restricting TRAIL expression to GD2⁺ DMG cells; 2. assess how ONC206/TRAIL repolarize human macrophages using phenotypic, transcriptomic, and metabolic analyses, with exploratory in vivo studies corroborating macrophage shift and tumor apoptosis. ONCAR-TRAIL combines my CAR T expertise with the resources of the Universities of Zurich and Geneva. Enhancing CAR T cell efficacy and modulating the DMG TME provide a framework for novel translational therapies against DMG through Pediatric Neuro-Oncology Consortium, the Diffuse Midline Glioma-ACT initiative, and the Children’s Brain Tumor Network.