Synergistic antitumor efficacy of rMV-Hu191 and Olaparib in pancreatic cancer by generating oxidative DNA damage and ROS-dependent apoptosis.

Background: Malignancies with BRCA1/2 deficiencies are particularly sensitive to PARP inhibitors. Thus, combining PARP inhibitors with agents that impair DNA damage repair to treat BRCA1/2 wild-type PDAC could broaden the clinical use of these promising PARP inhibitors. Here we examined the synergism and mechanism of oncolytic measles virus (rMV-Hu191) with a PARP inhibitor (Olaparib) in vitro and in vivo.

Methods: The cell viability assay, cell cycle analysis, colony formation assay, TCID 50 method, western blotting, flow cytometry, DNA comet assay, Mice bearing PDAC xenografts, IF, IHC and TUNEL assay were performed to explore the antitumor efficacy and underlying mechanisms.

Results: In this study, we explored the antitumor activities of rMV-Hu191 and Olaparib in two PDAC cell lines harboring wild-type BRCA1/2 genes. Compared to monotherapy, the combination of rMV-Hu191 and Olaparib was able to synergistically cause growth arrest, apoptotic cell death and DNA damage, accompanying with excessive oxidative stress. Mechanistically, the data indicated that the observed synergy depended on the oxidative DNA damage and ROS-dependent apoptosis generating by rMV-Hu191 combined with Olaparib in human PDAC cells. Tumor inhibition and prolonged survival of PDAC mice xenografts in vivo confirmed the synergism of combinational treatment with trivial side-effects.

Conclusions: Our findings firstly suggested that combination treatment with rMV-Hu191 and Olaparib had a profound and synergistic therapeutic effect against human PDAC through synthetic lethality. In conclusion, we recommend combining oncolytic rMV-Hu191 with a PARP inhibitor (Olaparib) as a novel therapeutic strategy and provided a potential mechanism for advanced PDAC regardless of BRCA mutation status.