PARP inhibitors in ovarian cancer: evidence for maintenance and treatment strategies

Ovarian cancer is the most lethal gynecologic malignancy. The long-established primary treatment for ovarian cancer consisted of surgical cytoreduction followed by platinum-based chemotherapy. Unfortunately, this therapeutic approach is related to a high frequency of early relapses. Further chemotherapy is necessary for recurrent disease, but very few patients can be cured. Poly (ADP-ribose) polymerase (PARP) is a family of proteins involved in various DNA repair activities. PARP inhibition leads to synthetic lethality in BRCA mutated or homologous recombination deficient tumors. The development of PARP inhibitors has changed the way ovarian cancer patients are treated. Olaparib, niraparib and rucaparib are orally active and have demonstrated efficacy for both maintenance and treatment settings. These three drugs have gained regulatory approval for different clinical circumstances. They have an acceptable toxicity profile and are generally well tolerated. Common class toxicities include hematologic effects, gastrointestinal effects and fatigue. Moreover, new treatment strategies that combine PARP inhibitors with other drugs, such as angiogenic agents, are being explored. The purpose of this review is to describe the evidence that define the current clinical role of PARP inhibitors in ovarian cancer. The implementation of rationally designed new clinical trials will be crucial to facilitate the best selection of patients and to continue improving clinical outcomes.