Fig. 4.

ONC201 and ONC206 activate the integrated stress response (ISR) leading to DMG cell apoptosis. (A) Protein expression of ISR biomarkers ATF4, DR5, CHOP, and p-eIF2α increased, while ClpX decreased, after 72 hrs at indicated doses. (B) Protein expression of apoptosis biomarkers cleaved caspase-7, PARP, cleaved-PARP and XIAP after 72 hrs at indicated doses. (C) ONC201 or ONC206 treated subcutaneous DMG tumor model in mice revealed a higher expression of ATF4 and DR5, and lower expression of ClpX and NDUFA12. Representative tumor sections, scale bar 50 µm and 20 µm in inset. (D) Median survival significantly increased in DMG PDX models treated with ONC201 (117 days, P = .01) or ONC206 (113 days, P = .01) compared to vehicle control (100 days). Drug combination (50mg/kg each) increased median survival (125 days) when compared to untreated (P = .01), single therapy with ONC201 (P = .03), or ONC206 (P = .02). Mice (n = 3) were treated (IP, weekly) for 6 weeks, starting at 14 days post-tumor implantation. (E) Histological analysis of DMG PDX tumors at necropsy showed ClpX downregulation in the combination treatment compared to untreated control.