A Compendium of Syngeneic, Transplantable Pediatric High-Grade Glioma Models Reveals Subtype-Specific Therapeutic Vulnerabilities

Pediatric high-grade gliomas (pHGG) are lethal, incurable brain tumors frequently driven by clonal mutations in histone genes. They often harbor a range of additional genetic alterations that correlate with different ages, anatomic locations, and tumor subtypes. We devel-oped models representing 16 pHGG subtypes driven by different combinations of alterations targeted to specifi c brain regions. Tumors developed with varying latencies and cell lines derived from these models engrafted in syngeneic, immunocompetent mice with high penetrance. Targeted drug screening revealed unexpected selective vulnerabilities-H3.3G34R/PDGFRAC235Y to FGFR inhibition, H3.3K27M/PDGFRAWT to PDGFRA inhibition, and H3.3K27M/PDGFRAWT and H3.3K27M/PPM1D & UDelta;C/PIK3CAE545K to combined inhibition of MEK and PIK3CA. Moreover, H3.3K27M tumors with PIK3CA, NF1, and FGFR1 mutations were more inva-sive and harbored distinct additional phenotypes, such as exophytic spread, cranial nerve invasion, and spinal dissemination. Collectively, these models reveal that different partner alterations produce distinct effects on pHGG cellular composition, latency, invasiveness, and treatment sensitivity. SIGNIFICANCE: Histone-mutant pediatric gliomas are a highly heterogeneous tumor entity. Differ-ent histone mutations correlate with different ages of onset, survival outcomes, brain regions, and partner alterations. We have developed models of histone-mutant gliomas that refl ect this anatomic and genetic heterogeneity and provide evidence of subtype-specifi c biology and therapeutic targeting.

Automated summary

Pediatric high-grade gliomas (pHGG) are heterogeneous brain tumors driven by clonal mutations in histone genes. We developed models representing 16 pHGG subtypes with different genetic alterations, which showed different treatment sensitivities and invasiveness. These models provide evidence for subtype-specific biology and therapeutic targeting in histone-mutant gliomas.