Combination therapy with poly(adenosine diphosphate-ribose) polymerase (PARPi) and androgen receptor signaling pathway (ARPi) inhibitors for metastatic castration-resistant prostate cancer

Metastatic castration-resistant prostate cancer (mCRPC) is a heterogeneous disease with varying clinical and molecular subtypes. Almost one-third of patients have abnormalities in homologous recombinant repair genes. Again, about one third of these mutations affect the BReast CAncer 1 or 2 (BRCA 1 or BRCA 2) genes, which generally render tumours receptive to treatment with poly(adenosine diphosphate-ribose) polymerase inhibitors (PARPi). In 2020 the PARPi olaparib was approved for the treatment of mCRPC after progression with a new hormonal drug (androgen receptor signaling pathway inhibitors, ARPi). In 2022 and 2023 approval of two combination therapies followed, each combining a PARPi and an ARPi (olaparib plus abiraterone and niraparib plus abiraterone). The combination of talazoparib plus enzalutamide will be approved soon. This article introduces the pivotal clinical trials that led to the approval of the respective substances, reports the side effects that may occur during therapy with PARPi plus ARPi, and offers recommendations for management of these side effects.