Targeting PDGFRA-SHP2 signaling enhances radiotherapy in IDH1-mutant glioma

Isocitrate dehydrogenase mutant (IDH-mut) gliomas represent a distinct subtype of glioma, characterized by a relatively better prognosis compared to IDH wildtype (wt) glioblastoma (GBM). Despite this advantage, these tumors remain incurable due to the limited availability of effective treatments. Targeting SHP2, a non-receptor protein tyrosine phosphatase, is a promising therapeutic strategy for several types of human cancers. In this study, we aim to determine the efficacy of SHP inhibition in IDH-mut gliomas.

Bioinformatic and biological analyses revealed increased expression and activation of the PDGFRA-SHP2-ERK pathway in clinical IDH-mut gliomas and patient-derived IDH-mut glioma stem-like cells (GSCs). The effects of SHP2 inhibition, alone or with radiation therapy (RT), were assessed through assays including cell growth, sphere formation, cell differentiation markers, flow cytometry, immunoblotting, immunohistochemistry, and orthotopic brain tumor xenografts.

PDGFRA expression was elevated in IDH-mut gliomas and GSCs, activating the SHP2-ERK pathway. SHP099, a SHP2 inhibitor, reduced GSC tumorigenicity in vitro and in vivo by disrupting SHP2-ERK signaling and promoting differentiation. SHP099 also enhanced cytotoxicity of RT, the standard treatment for IDH-mut glioma, in IDH-mut GSCs and orthotopic glioma models. Mechanistically, the PDGFRA-SHP2-ERK axis is activated in IDH-mut gliomas and RT further activates this pathway. Targeting SHP2 suppressed ERK signaling thereby enhancing the therapeutic effect of RT.

Combining SHP2 inhibition with RT is a promising therapeutic avenue for IDH-mut glioma by suppressing the activated SHP2-ERK axis.