Introduction: The implementation of poly-ADP-ribose polymerase (PARP) inhibitors for therapy has created potential treatments for a wide spectrum of malignancies involving DNA damage repair gene abnormalities. PARPs are a group of enzymes that are responsible for detecting and repairing DNA damage and therefore play a key role in maintaining cell function and integrity. PARP inhibitors are drugs that target DNA repair deficiencies. Inhibiting PARP activity in cancer cells causes cell death. Areas covered: This review summarizes the role of PARP inhibitors in the treatment of cancer. We performed a systematic literature search in February 2019 in the electronic databases PubMed and EMBASE. Our search terms were the following: PARP, PARP inhibitors, PARPi, Poly ADP ribose polymerase, cancer treatment. We discuss PARP inhibitors currently being investigated in cancer clinical trials, their safety profiles, clinical resistance, combined therapeutic approaches and future challenges. Expert Opinion: The future could bring novel PARP inhibitors with greater DNA trapping potential, better safety profiles and improved combined therapies involving hormonal, chemo-, radio- or immunotherapies. Progress may afford wider indications for PARP inhibitors in the treatment of cancer and the utilization for cancer prevention in high-risk mutation carriers. Research efforts should focus on identifying novel drugs that target DNA repair deficiencies.
Keywords: BRCA mutations; BRCAness; DNA damage response; PARP enzymes; PARP inhibitors; breast cancer; ovarian cancer; prostate cancer.