CDC7 Inhibition Potentiates Antitumor Efficacy of PARP Inhibitor in Advanced Ovarian Cancer

PARP inhibitors have demonstrated remarkable clinical efficacy in treating ovarian cancer (OV) patients with BRCA1/2 mutations. However, drug resistance inevitably limits their clinical applications and there is an urgent need for improved therapeutic strategies to enhance the clinical utility of PARP inhibitors, such as Olaparib. Here, we present compelling evidence that PARP inhibitor sensitivity is associated with cell cycle dysfunction, independent of homologous recombination deficiency (HRD) /BRCA status. Through high-throughput drug screening with a cell cycle kinase inhibitor library, we identified XL413, a potent CDC7 inhibitor, which can synergistically enhance the anti-cancer efficacy of Olaparib. Mechanistically, we demonstrate that the combined administration of XL413 and Olaparib induced considerable DNA damage and DNA replication stress, leading to increased sensitivity to Olaparib. Additionally, a robust type-I interferon response was triggered through the induction of the cGAS/STING signaling pathway. Using a murine syngeneic tumor model, we further demonstrate that the combination treatment enhanced antitumor immunity, resulting in tumor regression. Collectively, this study presents a novel treatment strategy for patients with advanced OV by combining CDC7 and PARP inhibitiors, offering a promising therapeutic approach forpatients whith limited response to PARP inhibitors. Overall design: RNA-sequencing (RNA-seq) was conducted in OVCAR5 cells treated with Olaparib in the presence or absence of XL413.