Patient-reported Outcomes for Patients with Metastatic Castration-resistant Prostate Cancer and BRCA1/2 Gene Alterations: Final Analysis from the Randomized Phase 3 MAGNITUDE Trial.

Abstract

Background and objective: The phase 3 MAGNITUDE trial assessed the efficacy and safety of niraparib 200 mg and abiraterone acetate 1000 mg plus prednisone 10 mg (AAP) in patients with metastatic castration-resistant prostate cancer (mCRPC) and alterations in homologous recombination repair (HRR) genes. Here we report final analysis results for patient-reported outcomes (PROs) in the HRR⁺ cohort with a focus on BRCA1/2 alterations (BRCA⁺).

Methods: Protocol-specified endpoints evaluated patient-reported symptoms, health-related quality of life (HRQoL), and tolerability (side-effect bother) using the Brief Pain Inventory-Short Form (BPI-SF), Functional Assessment of Cancer Therapy-Prostate (FACT-P), and EQ-5D-5L questionnaires. Evaluations were completed on day 1 of designated treatment cycles and during follow-up.

Key findings and limitations: All patients with BRCA⁺ mCRPC (n = 225) were included in the PRO analyses with average on-treatment PRO compliance >80% when completed on-site. Time to deterioration in pain according to BPI-SF and FACT-P scores did not significantly differ between niraparib + AAP and placebo + AAP. During treatment, EQ-5D-5L revealed no clinically meaningful differences in overall HRQoL between treatment arms in the BRCA+ subgroup. Finally, tolerability was similar between arms; side effect bother rated as "not at all" or "a little bit" ranged from 79.8% to 95.9% during treatment. Limitations include a sample size that may not have been powered to detect a difference in PROs.

Conclusions and clinical implications: Treatment with niraparib + AAP maintained HRQoL with minimal side-effect bother reported by most patients with BRCA⁺ mCRPC. Differences between treatment groups in time to pain deterioration did not meet conventional levels of statistical significance. The MAGNITUDE trial is registered on ClinicalTrials.gov as NCT03748641.