From Antipsychotic to Antitumor Agent: Cariprazine Suppresses Glioblastoma via D2/D3-ARRB2 Axis Modulation

Background: Glioblastoma (GBM) is among the malignant tumors with the lowest five-year survival rate. Current treatments offer limited efficacy and first-line options are scarce, highlighting the urgent need for novel drugs. Cariprazine can cross the blood–brain barrier and has been reported to inhibit certain tumors; however, its effect on GBM remains unknown. This study aims to elucidate its anti-GBM effects and mechanisms. Methods: Cell proliferation and apoptosis were assessed by wound healing, Transwell, colony formation assays, flow cytometry and JC−10 staining. Co-immunoprecipitation (Co-IP) examined the effect of cariprazine on D2/D3–ARRB2 interaction. Direct binding of cariprazine to ARRB2 was determined by molecular docking and CETSA. Western blotting and immunofluorescence detected changes in proliferation and apoptosis-related proteins. In vivo anti-GBM activity was evaluated in subcutaneous mouse models. Results: Cariprazine inhibited GBM cell proliferation and migration, promoted apoptosis, and showed low astrocyte toxicity. In mice, it suppressed GBM allograft growth without overt systemic toxicity. These effects were mediated through D2/D3 receptors, as cariprazine disrupted the D2/D3–ARRB2 interaction and thereby inhibited ERK signaling. It also upregulated ARRB2, further inhibiting the growth of GBM. Molecular docking and CETSA confirmed the direct binding of cariprazine to ARRB2 at LEU-245 and PHE-246. Conclusions: This study is the first to repurpose cariprazine for GBM, elucidating a unique ARRB2-centered dual mechanism, thus offering a new therapeutic strategy.