However, when PARP inhibitors were used as maintenance therapy (for ovarian cancer, NCT03737643, NCT03740165 and NCT03598270; for NSCLC, NCT02944396), they were used following ICIs, while in some other clinical trials, PARP inhibitors and CDK4/6 inhibitors were used before ICIs (NCT03579784, NCT03842228 and NCT03781960). Here, PARP1 is linked to ovarian cancer.