Double trouble for prostate cancer: synergistic action of AR blockade and PARPi in non-HRR mutated patients

The efficacy and safety of PARP inhibitors in mCRPC with HRR mutation in second-line treatment: a systematic review and bayesian network meta-analysis

BACKGROUND

Poly (ADP- ribose) polymerase inhibitors (PARPi) has been increasingly adopted for metastatic castration-resistance prostate cancer (mCRPC) patients with homologous recombination repair deficiency (HRD). However, it is unclear which PARPi is optimal in mCRPC patients with HRD in 2nd -line setting.

METHOD

We conducted a systematic review of trials regarding PARPi- based therapies on mCRPC in 2nd -line setting and performed a Bayesian network meta-analysis (NMA). Radiographic progression-free survival (rPFS) was assessed as primary outcome. PSA response and adverse events (AEs) were evaluated as secondary outcomes. Subgroup analyses were performed according to specific genetic mutation.

RESULTS

Four RCTs comprised of 1024 patients (763 harbored homologous recombination repair (HRR) mutations) were identified for quantitative analysis. Regarding rPFS, olaparib monotherapy, rucaparib and cediranib plus olaparib showed significant improvement compared with ARAT. Olaparib plus cediranib had the highest surface under cumulative ranking curve (SUCRA) scores (87.5%) for rPFS, followed by rucaparib, olaparib and olaparib plus abiraterone acetate prednisone. For patients with BRCA 1/2 mutations, olaparib associated with the highest probability (98.1%) of improved rPFS. For patients with BRCA-2 mutations, olaparib and olaparib plus cediranib had similar efficacy. However, neither olaparib nor rucaparib showed significant superior effectiveness to androgen receptor-axis-targeted therapy (ARAT) in patients with ATM mutations. For safety, olaparib showed significantly lower ≥ 3 AE rate compared with cediranib plus olaparib (RR: 0.72, 95% CI: 0.51, 0.97), while olaparib plus cediranib was associated with the highest risk of all-grade AE.

CONCLUSION

PARPi-based therapy showed considerable efficacy for mCRPC patients with HRD in 2nd -line setting. However, patients should be treated accordingly based on their genetic background as well as the efficacy and safety of the selected regimen.

TRIAL REGISTRATION

CRD42023454079.

Poly (ADP-ribose) Polymerase Inhibitors in Patients with Metastatic Castration-Resistant Prostate Cancer: A Meta-Analysis of Randomized Controlled Trials

Context: Several recent randomized controlled trials (RCTs) have reported on the survival benefits of poly (ADP-ribose) polymerase inhibitors (PARPi) compared to standard-of-care (SOC) treatment (enzalutamide, abiraterone, or docetaxel) in patients with metastatic castration-resistant prostate cancer (mCRPC). However, there is a limited integrated analysis of high-quality evidence comparing the efficacy and safety of PARPi and SOC treatments in this context. Objective: This study aims to comprehensively analyze the survival benefits and adverse events associated with PARPi and SOC treatments through a head-to-head meta-analysis in mCRPC. Evidence acquisition: A systematic review search was conducted in PubMed, Embase, Clinical trials, and the Central Cochrane Registry in July 2023. RCTs were assessed following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. The systematic review was prospectively registered on PROSPERO (CRD42023441034). Evidence synthesis: A total of 8 studies, encompassing 2341 cases in the PARPi treatment arm and 1810 cases in the controlled arm, were included in the qualitative synthesis. The hazard ratio (HR) for radiographic progression-free survival (rPFS) and overall survival (OS) were 0.74 (95% CI, 0.61-0.90) and 0.89 (95% CI, 0.80-0.99), respectively, in the intention-to-treatment patients. For subgroup analysis, HRs for rPFS and OS in the BRCA-mutated subgroup were 0.39 (95% CI, 0.28-0.55) and 0.62 (95% CI, 0.38-0.99), while in the HRR-mutated subgroup, HR for rPFS was 0.57 (95% CI, 0.48-0.69) and for OS was 0.77 (95% CI, 0.64-0.93). The odds ratio (OR) for all grades of adverse events (AEs) and AEs with severity of at least grade 3 were 3.86 (95% CI, 2.53-5.90) and 2.30 (95% CI, 1.63-3.26), respectively. Conclusions: PARP inhibitors demonstrate greater effectiveness than SOC treatments in HRR/BRCA-positive patients with mCRPC. Further research is required to explore ways to reduce adverse event rates and investigate the efficacy of HRR/BRCA-negative patients.