Activated ADAM10 targeting antibody 1H5 suppresses NOTCH-driven glioma progenitors

Background: High-grade gliomas (HGGs) remain associated with high morbidity, mortality, and invariable recurrence after neurosurgical resection and chemoradiation. A major contributor to treatment failure is a population of stem-like glioma progenitor cells (GPCs) that depend on NOTCH-signaling for self-renewal and survival; clinical attempts to inhibit NOTCH with {gamma}-secretase inhibitors failed due to systemic toxicity. Methods: Here, we investigate the anti-HGG therapeutic potential of a fully-human monoclonal antibody, 1H5, that selectively targets activated-ADAM10, an -secretase required for NOTCH receptor processing, with high tumor specificity. We show that ADAM10 is markedly overexpressed and highly activated in primary and recurrent HGGs, using patient tissue, RNA-sequencing data, and early-passage HGG cell lines. Results: Across a panel of patient-derived HGG lines, sensitivity to 1H5 correlates with the cell-surface levels of activated-ADAM10, and shRNA-mediated ADAM10 knockdown recapitulates the growth-inhibitory effects of 1H5. ADAM10 inhibition suppresses NOTCH-pathway components and target genes, reduces expression of GPC markers, and impairs neurosphere formation while depleting Sox2- and Ki67-positive cells. We further find that 1H5 induces HGG cell death predominantly via necroptosis, characterized by survivin loss and increased phosphorylated MLKL and by transcriptional changes in necroptosis-related genes. In three-dimensional explants derived from primary HGG, 1H5 reduces growth and GPC marker expression while increasing TUNEL staining. Finally, convection-enhanced delivery of 1H5 in orthotopic xenograft models achieves high local intracranial concentrations, slows tumor growth, and prolongs survival, with regional pharmacodynamic effects consistent with NOTCH pathway suppression and necroptosis.