Clinical Advances in Hematology & OncologyThe Addition of PARP Inhibition to Androgen Receptor Pathway Inhibition in Metastatic Hormone-Sensitive Prostate Cancer

📋 Regulatory Action / Label Change

The phase 3 AMPLITUDE trial randomized 696 patients with HRR-deficient metastatic hormone-sensitive prostate cancer to abiraterone plus niraparib or abiraterone plus placebo. Results drove FDA and EMA label extensions for niraparib plus abiraterone in BRCA-mutant mHSPC.

Clinical Considerations

• rPFS hazard ratio of 0.52 in BRCA-mutant patients; HR 0.57 in the broader HRR effector subgroup, 0.63 in intention-to-treat
• Time to symptomatic progression significantly improved (HR 0.44 BRCA-mutant; HR 0.50 ITT); OS data remain immature with non-significant trends
• Grade 3-4 toxicity reached 75% vs 59%; any-grade anemia 52%, grade 3-4 anemia 30%, and 25% required transfusion
• Treatment effect was heterogeneous across non-BRCA HRR genes, and the label extensions excluded non-BRCA alterations

Practice Applications

• Consider earlier tissue-based HRR testing at mHSPC diagnosis to identify BRCA candidates
• Recognize that PSMA PET-only metastatic disease falls outside the AMPLITUDE population
• Monitor hematinics, hemoglobin, and blood pressure throughout niraparib exposure
• Interpret germline BRCA findings as a trigger for cascade family testing