A boost or a redundancy? on the value of combination of androgen receptor signal inhibitor and PARP inhibitor for advanced prostate cancer

Poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi), as a novel endocrine therapy, has been investigated in patients with metastatic castration-resistant prostate cancer (mCRPC) in recent years. Multiple large-scale clinical trials have consistently demonstrated that various PARP inhibitors, including olaparib, rucaparib, niraparib, and talazoparib, confer longer radiographic progression-free survival (rPFS) compared to new hormonal agents (NHA) in mCRPC patients with homologous recombination deficiency (HRD). Moreover, the incidence of grade 3 and above adverse events did not significantly increase. Additionally, when combined with androgen receptor signaling inhibitors (ARSI), olaparib, niraparib, and talazoparib have shown significant extension of rPFS but also an increased occurrence of serious adverse events in HRD-positive patients. Only PROpel yielded positive results among the homologous recombination repair (HRR) mutation negative population. Therefore, it remains uncertain whether ARSI-PARPi combination therapy should be considered as first-line treatment for mCRPC patients without HRR mutations. In this review article, we aim to elucidate the necessity and feasibility of combination therapy versus monotherapy specifically within the HRR mutant population while exploring its potential applicability to other non-HRR mutant subtypes. Furthermore, we conducted a comprehensive search on registered clinical trials at present to summarize the research progress of PARP inhibitors in prostate cancer patients at different disease stages.