ASCO 2026 Plenary: PROTEUS Phase 3 — Perioperative Apalutamide 10× More Likely to Achieve Complete Pathologic Response in High-Risk Localized Prostate Cancer

The Phase 3 PROTEUS trial, presented by Dr. Mary-Ellen Taplin (Dana-Farber Cancer Institute) at the ASCO 2026 Plenary Session, demonstrated that 1 year of perioperative apalutamide (Erleada; Johnson & Johnson) combined with androgen deprivation therapy (ADT) — given for 6 months before and 6 months after radical prostatectomy — substantially improves outcomes in high-risk localized or locally advanced prostate cancer. The trial enrolled 2,109 patients from 118 centers across 18 countries with a median follow-up of 61.7 months. For the primary endpoint of pathological complete response or minimal residual disease (pCR/MRD), apalutamide + ADT achieved 8.9% vs. 1.0% with placebo + ADT (odds ratio 10.17, 95% CI 5.27–19.64; p<0.0001). Full pathological complete response (ypT0) occurred in 5.1% vs. 0.4% of patients. The 5-year metastasis-free survival rate was 78.2% (apalutamide) vs. 73.5% (placebo), a 20% reduction in metastasis or death risk. Event-free survival at 5 years was approximately 57.1 vs. 38.4 months. High-risk localized prostate cancer affects approximately 50,000 men annually in the US who are eligible for radical prostatectomy — the trial establishes a new perioperative intensification standard that breaks a decades-long treatment paradigm where hormone therapy was reserved for metastatic disease. The J&J press release noted this represents a 'fundamental shift' in the approach to high-risk localized prostate cancer.