Apalutamide improves MFS in high-risk prostate cancer
By Sudha Thakor
Apalutamide plus androgen deprivation therapy (ADT) improves metastasis-free survival (MFS) versus ADT alone in patients with high-risk localized or locally advanced prostate cancer undergoing radical prostatectomy, according to the phase 3 PROTEUS trial (NCT03767244) presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, USA.
Mary-Ellen Taplin (Dana-Farber Cancer Institute, Boston, Massachusetts, USA) presented the data, noting that PROTEUS “is the first to demonstrate that 1 year of perioperative apalutamide and ADT significantly improves metastasis-free survival.”
After a median follow-up of approximately 5 years, apalutamide plus ADT reduced the risk of metastasis or death by 20% compared with ADT alone.
Findings from PROTEUS include:
- Higher pathologic response rates, with pathologic complete response or measurable residual disease achieved in 8.9% versus 1.0% of patients
- Lower risk of prostate cancer recurrence, with a 29% decrease observed with apalutamide plus ADT versus ADT alone
- Longer event-free survival, with a median of 57.1 months versus 38.4 months
- Longer time to subsequent therapy, with nearly 3 years’ difference in time to additional treatment
The trial enrolled 2,109 patients with newly diagnosed high-risk localized or locally advanced prostate cancer across 18 countries, making it the largest therapeutic study in this setting. Patients were randomized to receive apalutamide or placebo in combination with ADT for 6 months before and 6 months after radical prostatectomy.
Safety findings were generally consistent with the known profile of apalutamide, with a higher incidence of grade 3/4 treatment-related adverse events (27.5% vs 18.9%) observed in the apalutamide arm. Treatment-related adverse events leading to death were 0.7% versus 0.1% in the apalutamide arm compared to placebo arm, respectively.
Rash was reported more frequently with apalutamide, while other adverse events of special interest (grade ≥3), including fall, ischemic heart disease, and non-pathological fracture, occurred in both treatment groups. Treatment-related deaths were rare (<1%) but numerically higher in the apalutamide group, with several events associated with surgery. Taplin highlighted the importance of patient selection, particularly following protocol amendments.
Further analyses from PROTEUS are ongoing, including the evaluation of biomarkers and longer-term outcomes.
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