Development of PARP inhibitors in advanced prostate cancer

The relatively high prevalence of alterations in the homologous recombination repair (HRR) pathway described in advanced prostate cancer provides a unique opportunity to develop therapeutic strategies that take advantage of the decreased tumor ability to repair DNA damage. Poly ADP-ribose polymerase (PARP) inhibitors have been demonstrated to improve the outcomes of metastatic castration-resistant prostate cancer (mCRPC) patients with HRR defects, particularly in those with BRCA1/2 alterations. To expand the benefit of PARPi to patients without detectable HRR alterations, multiple studies are addressing potential synergies between PARP inhibition (PARPi) and androgen receptor pathway inhibitors (ARSi), radiation, radioligand therapy, chemotherapy, or immunotherapy, and these strategies are also being evaluated in the hormone-sensitive setting. In this review, we summarize the development of PARPi in prostate cancer, the potential synergies, and combinations being investigated as well as the future directions of PARPi for the management of the disease. Development of PARP inhibitors in advanced prostate cancerAlterations in the mechanisms responsible for repairing damaged DNA are frequently altered in advanced prostate cancer. This provides a unique opportunity to develop therapies that exploit the decreased ability of these prostate tumours to repair DNA. Poly ADP-ribose polymerase (PARP) inhibitors have been successfully used to treat other tumor types with similar deficiencies and recently, multiple studies have demonstrated its efficacy also in prostate cancer, particularly in tumors with BRCA1/2 alterations. To expand the benefit of PARPi to patients without detectable DNA repair alterations, multiple studies are addressing potential synergies between PARP inhibition (PARPi) and androgen receptor pathway inhibitors (ARSi), radiation, radiopharmaceuticals, chemotherapy and immunotherapy in different disease stages. In this review, we summarize the development of PARPi in prostate cancer, the potential synergies and combinations being evaluated as well as the future directions of PARPi for the management of the disease.