Novel poly-ADP-ribose polymerase inhibitor combination strategies in ovarian cancer
Purpose of review The recent United States Food and Drug Administration approvals of niraparib and olaparib as maintenance monotherapy for platinum-sensitive, high-grade ovarian cancers independent of BRCA status reflect a willingness to seek indications for poly-ADP-ribose polymerase (PARP) inhibitors beyond cancers with deleterious breast cancer 1 and breast cancer 2 mutations. In this review, I describe the rationale behind current PARP combination clinical trials with chemotherapies, angiogenesis inhibitors, cell cycle checkpoint inhibitors, and inhibitors of the phosphoinositide 3-kinase/AK thymoma/mechanistic target of rapamycin pathway. Recent findings PARP inhibitors have primarily been studied as monotherapy in cancers with homologous recombination repair defects based on an early understanding of PARP-1 as a base excision repair enzyme and the idea that abrogation of two DNA repair pathways cripples rapidly dividing cancer cells. It is now known that PARP-1 is a DNA damage sensor with much wider reaching roles in DNA repair processes and normal cellular functions, opening possibilities for PARP inhibitor use in other clinical contexts. Summary PARP inhibitor combination clinical trials are in the early stages, but will deepen our understanding of DNA repair mechanisms, cancer biology, and targeted therapies, thus contributing to the next iteration of therapeutic options for our patients.