As previously described, EZH2 affects the DNA damage repair response in tumor cells, and experiments in ovarian cancer cell lines, mouse models, and PDX models of ovarian cancer patients have verified that EZH2 promotes homologous recombination repair through H3K27me3 modification, while EZH2 inhibitor treatment prevents homologous recombination repair, thereby enhancing the antitumor effects of PARP inhibitors (Karakashev et al., 2020), which is described as a pharmacological synthetic lethal condition (e.g., Figure 1). This evidence concerns the gene PARP1 and ovarian cancer.