Dual targeting of the epigenome via FACT complex and histone deacetylase is a potent treatment strategy for DIPG

Diffuse intrinsic pontine glioma (DIPG) is an aggressive and incurable childhood brain tumor for which new treatments are needed. CBL0137 is an anti-cancer compound developed from quinacrine that targets facilitates chromatin transcription (FACT), a chromatin remodeling complex involved in transcription, replication, and DNA repair. We show that CBL0137 displays profound cytotoxic activity against a panel of patient-derived DIPG cultures by restoring tumor suppressor TP53 and Rb activity. Moreover, in an orthotopic model of DIPG, treatment with CBL0137 significantly extends animal survival. The FACT subunit SPT16 is found to directly interact with H3.3K27M, and treatment with CBL0137 restores both histone H3 acetylation and trimethylation. Combined treatment of CBL0137 with the histone deacetylase inhibitor panobinostat leads to inhibition of the Rb/E2F1 pathway and induction of apoptosis. The combination of CBL0137 and panobinostat significantly prolongs the survival of mice bearing DIPG orthografts, suggesting a potential treatment strategy for DIPG. [Display omitted] •CBL0137 inhibits DIPG tumor growth and restores H3K27me3 through FACT inhibition•Co-administration of CBL0137 and panobinostat enhances survival in DIPG xenografts•CBL0137 and panobinostat synergistically inhibit the Rb/E2F1 pathway and restore H3K27me3 Ehteda et al. find that the histone chaperon FACT is an oncogenic target in diffuse intrinsic pontine glioma. Pharmacological inhibition of FACT with CBL0137 reverses the effect of H3K27M. Co-administration of CBL0137 and panobinostat significantly prolongs survival in two aggressive DIPG in vivo models.