Olaparib Enhances the Efficacy of Third‐Generation Oncolytic Adenoviruses Against Glioblastoma by Modulating DNA Damage Response and p66shc‐Induced Apoptosis.

Aims: Patients with glioblastoma multiforme (GBM) do not benefit from current cancer treatments, and their prognosis is dismal. This study aimed to investigate the potential synergistic effects of TS‐2021, a third‐generation oncolytic adenovirus, combined with the PARP inhibitor olaparib in GBM. Methods: TS‐2021's impact on p66shc‐induced apoptosis, DNA damage response, and poly (ADP‐ribose) polymerase (PARP) activation was evaluated in GBM cells. The synergistic effect of TS‐2021 and olaparib was examined in GBM cell lines and an immunocompetent mouse model of GBM. Mechanistic studies focused on the role of p66shc phosphorylation in the observed effects. Results: TS‐2021 triggered p66shc‐induced apoptosis, DNA damage response, and PARP activation. The combination of TS‐2021 and olaparib synergistically increased cell apoptosis and DNA damage and reduced PARP expression compared to monotherapy. Olaparib promoted TS‐2021 replication and release in GBM cells. Mechanistically, olaparib combined with TS‐2021 upregulated p66shc phosphorylation, enhancing tumor cell apoptosis. In vivo, the combination therapy inhibited tumor growth and prolonged survival, confirming the synergistic effect. Conclusion: This study is the first to suggest that TS‐2021 sensitizes GBM cells with wild‐type BRCA1/2 to olaparib. The combination of TS‐2021 and olaparib shows a synergistic therapeutic effect against GBM, providing a promising treatment strategy. [ABSTRACT FROM AUTHOR]