Adeno-associated virus-clustered regularly interspaced short palindromic repeats/cas9‑mediated ovarian cancer treatment targeting PD-L1.

The response rate of antibody therapy targeting immune checkpoint molecules in ovarian cancer is insufficient. This study aimed to develop a novel gene immunotherapy model targeting programmed death ligand 1 (PD-L1) in vivo in ovarian cancer using adeno-associated virus (AAV)-clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 and investigate its efficacy. In vitro, we produced PD-L1-AAV particles to knock out PD-L1. PD-L1-AAV particles were transduced into the murine ovarian cancer cell line ID8. PD-L1 expression at the cellular level was significantly decreased following treatment with PD-L1-AAV particles compared with control-AAV particles. In the peritoneal dissemination model, the survival time was significantly longer in the PD-L1-AAV particles intraperitoneally injected group than that in the control group. Furthermore, intratumoral lymphocyte recruitment was analyzed by immunohistochemistry, and the number of intratumoral CD4(+) and CD8(+) T cells was significantly higher, whereas that of Foxp3(+) Treg cells was significantly lower in the PD-L1-AAV particles injected group than in the control group. No severe adverse events in normal organs, such as the lungs, spleen, liver, and kidney, were observed. These results suggest that PD-L1-targeted therapy by genome editing using AAV-CRISPR/Cas9 is a novel gene-immune therapeutic strategy for ovarian cancer.