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Updated: Jan 9, 2026
A Bioluminescent and Fluorescent Orthotopic Syngeneic Murine Model of Androgen-dependent and Castration-resistant Prostate Cancer
Published on: March 6, 2018
Can PARP Inhibitors Benefit Patients with Homologous Recombination Repair-Proficient Castration-Resistant Prostate
Susu Zhou1, Devashish Desai2, Noriko Kishi3
1Division of Hematology and Oncology, Department of Medicine, SUNY Upstate Medical University, Syracuse, NY, 13210, USA. zhous@upstate.edu.
Background:
PARP inhibitor (PARPi)-based therapy is a well-established treatment modality for metastatic castration-resistant prostate cancer (mCRPC) harboring homologous recombination repair (HRR) deficiencies. However, its clinical efficacy in mCRPC without HRR alterations remains undefined.
Objective:
This study aimed to evaluate the efficacy of PARPis in HRR-proficient mCRPC.
Methods:
A systematic database search was conducted to identify clinical trials evaluating the efficacy of PARPi-based therapies in patients with HRR-proficient mCRPC. Searches were performed using PubMed, Embase Cochrane Library, Web of Science, and relevant international conference proceedings. Both single-arm and pairwise meta-analytical approaches were employed to assess the efficacy of PARPis in HRR-proficient mCRPC, while concurrently comparing the estimates with those from HRR-deficient populations within the same trials.
Results:
A total of eight single-arm trials and eight randomized controlled trials were included, comprising 3314 patients, of whom 1727 were HRR-proficient. In the single-arm meta-analysis, the pooled prostate-specific antigen (PSA) response (≥ 50% decrease from baseline) rate was 18% (95% CI 9-29, I2 = 82%) in the HRR-proficient subpopulation, and 46% (95% CI 35-59, I2 = 63%) in the HRR-deficient subpopulation, with a significant difference between subpopulations (p = 0.003). The pooled 12-month progression-free survival (PFS) rate was 42% (95% CI 29-57, I2 = 93%) in the HRR-proficient subpopulation and 57% (95% CI 48-67, I2 = 72%) in the HRR-deficient subpopulation. No significant difference was observed between the two subpopulations (p = 0.177). Subgroup analyses based on treatment regimens (PARPi monotherapy, PARPi plus androgen receptor axis-targeted (ARAT) agents, PARPi plus immune checkpoint inhibitors, and PARPi plus others) also revealed no significant difference in efficacy between HRR-proficient and HRR-deficient subpopulations. In the pairwise meta-analysis, the addition of PARPi was associated with a significantly longer PFS compared with treatment without PARPi in both HRR-proficient and HRR-deficient subpopulations, with hazard ratios of 0.69 (95% CI 0.60-0.80, I2 = 32%) and 0.60 (95% CI 0.50-0.72, I2 = 16%), respectively. Also, there was no statistically significant difference (p = 0.22) between the two subpopulations. PARPi plus ARAT showed a trend toward improved overall survival in HRR-proficient patients, with a more pronounced benefit observed in HRR-deficient patients.
Conclusions:
The use of PARPis in the treatment of CRPC demonstrated a significant improvement in PFS irrespective of HRR status. Even in the HRR-proficient subpopulation, PARPi-based therapy conferred encouraging PFS benefits, underscoring its potential clinical relevance beyond HRR-deficient settings. Further biomarker analyses are warranted to refine patient selection and optimize therapeutic strategies.
