CHEK1 and ovarian cancer: PARPi was also combined with many other ICB in ovarian cancer, such as inhibitors target phosphatidylinositol-4,5- bisphosphate 3-kinase (PI3K) (42, 43), V-akt murine thymoma viral oncogene homolog (AKT) (44), ATR (45, 46), heat shock protein 90 (HSP90) (47, 48), checkpoint kinase 1 (CHK1) (49), cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) (50), salt-inducible kinase 2 (SIK2) (51), insulin-like growth factor-1 receptor (IGF-1R) (52).