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Updated: May 12, 2026
Sequencing Small Non-coding RNA from Formalin-fixed Tissues and Serum-derived Exosomes from Castration-resistant Prostate Cancer Patients
Published on: November 19, 2019
PARP Inhibitors for Metastatic CRPC: More Answers than Questions, a Systematic Review and Meta-Analysis
Ray Manneh1, Javier Molina-Cerrillo2, Guillermo de Velasco3
1Medical Oncology Department, Sociedad de Oncología y Hematología del César, Valledupar 200001, Colombia.
Abstract:
PARP inhibitors (PARPi), alone or in combination with androgen receptor signaling inhibitors (ARSi), have shown clinical benefit in metastatic castration-resistant prostate cancer (mCRPC), particularly in tumors with homologous recombination repair (HRR) gene alterations. Recent data from the TALAPRO-2 trial complete the current evidence on PARPi-ARSi combination strategies in this setting. Background/Objectives: To evaluate the efficacy and safety of PARPi-based therapies-monotherapy and combination with ARSi-in patients with mCRPC, focusing on molecular subgroups defined by DNA repair alterations. Methods: We conducted a systematic review and meta-analysis of phase III randomized controlled trials (RCTs) assessing PARPi as monotherapy or in combination with ARSi. Searches were performed in PubMed, EMBASE, the Cochrane Library, and oncology conference proceedings up to February 2025. Outcomes included radiographic progression-free survival (rPFS), overall survival (OS), second progression-free survival (PFS2), and grade ≥3 adverse events (AEs). Data were pooled using a random-effects model, with subgroup analyses by DNA repair status. Results: Five RCTs (n = 2921) were I confirmincluded: three on combination therapy (n = 2271) and two on monotherapy (n = 650). Combination therapy improved rPFS in the ITT (HR = 0.64; 95% CI: 0.56-0.74), HRRm (HR = 0.55; 95% CI: 0.44-0.68), and BRCAm (HR = 0.33; 95% CI: 0.18-0.58) subgroups. OS was also improved in the ITT (HR = 0.80; 95% CI: 0.70-0.92), HRRm (HR = 0.68; 95% CI: 0.55-0.83), and BRCAm (HR = 0.54; 95% CI: 0.34-0.85) groups. No benefit was observed in non-HRRm patients. PFS2 favored combination therapy (HR = 0.77; 95% CI: 0.64-0.91). Grade ≥3 AEs were more frequent (RR = 1.44; 95% CI: 1.20-1.73). Monotherapy improved rPFS in ITT (HR = 0.46; 95% CI: 0.20-0.81) and BRCAm (HR = 0.33; 95% CI: 0.15-0.75); OS benefit was seen only in BRCAm (HR = 0.73; 95% CI: 0.57-0.95). Conclusions: PARPi therapies improve outcomes mainly in HRR- and BRCA-mutated mCRPC. Molecular selection is key to optimizing benefit and minimizing toxicity. Further research on the activity of PARPi combinations in non-HRR mutated mCRPC is needed to better understand the underlying mechanisms of efficacy.
Insights
PARP inhibitors (PARPi) combined with androgen receptor signaling inhibitors (ARSi) significantly improve outcomes for metastatic castration-resistant prostate cancer (mCRPC) patients with DNA repair gene alterations. Molecular profiling is crucial for treatment selection and toxicity management.
Area of Science:
- Oncology
- Genetics
- Pharmacology
Background:
- Metastatic castration-resistant prostate cancer (mCRPC) treatment has advanced with PARP inhibitors (PARPi) and ARSi.
- PARPi efficacy is particularly noted in tumors with homologous recombination repair (HRR) gene alterations.
- Recent trials like TALAPRO-2 add to the evidence base for PARPi-ARSi combinations.
Purpose of the Study:
- To systematically evaluate the efficacy and safety of PARPi-based therapies (monotherapy and combination with ARSi) in mCRPC.
- To focus on molecular subgroups defined by DNA repair alterations.
- To synthesize data from Phase III randomized controlled trials (RCTs).
Main Methods:
- Systematic review and meta-analysis of five Phase III RCTs (n=2921).
- Searches included PubMed, EMBASE, Cochrane Library, and conference proceedings up to February 2025.
- Outcomes analyzed: radiographic progression-free survival (rPFS), overall survival (OS), PFS2, and grade ≥3 adverse events (AEs). Subgroup analyses by DNA repair status were performed.
Main Results:
- Combination PARPi-ARSi therapy improved rPFS and OS in the overall population and significantly in HRR-deficient (HRRm) and BRCA-mutated (BRCAm) subgroups.
- No benefit was observed in non-HRRm patients for combination therapy.
- PARPi monotherapy also showed benefits in rPFS and OS, particularly in BRCAm patients. Higher rates of grade ≥3 AEs were noted with combination therapy.
Conclusions:
- PARPi-based therapies demonstrate significant clinical benefit primarily in mCRPC patients with HRR or BRCA mutations.
- Molecular selection based on DNA repair status is essential for optimizing treatment efficacy and minimizing toxicity.
- Further research is warranted to explore PARPi combinations in non-HRR mutated mCRPC and elucidate underlying mechanisms.
