Enzalutamide Combination Prolonged Survival in Early PSA Recurrence: The EMBARK Trial

After surgery or radiotherapy for prostate cancer, a renewed rise in blood PSA levels is called “biochemical recurrence” . A rapid rise in PSA like this (doubling time ≤9 months) means an increased future risk of disease spread and death.

Since the 1990s, the goal for most patients at this stage has been to put the disease “to sleep” using injections that suppress male hormones (ADT). However, before metastases develop, whether ADT alone truly prolongs survival remained unclear for many years, because most of our data came from the metastatic setting.

What changed with EMBARK? This large phase 3 trial showed that adding enzalutamide to ADT, when started at the PSA recurrence stage before metastases are visible on imaging, can reduce the risk of death by 40% over 8 years (HR 0.60). Thus, when PSA rises again, we no longer have to “wait and see”; early, more intensive hormone suppression can enable patients to live significantly longer.

These results were presented at the ESMO 2025 Presidential Symposiumand simultaneously published in the New England Journal of Medicine—entering the literature as a historic milestone demonstrating that, in early-stage prostate cancer, intensification not only lowers PSA, but also translates into longer survival as a proven benefit.

Detailed numbers and safety findings follow below; in brief, this trial ushered in the era of “early but smart intervention” in prostate cancer treatment.

Study Design

EMBARK was a phase 3 trial in men who, after prostate cancer treatment, had rising PSA again but no metastases detected on imaging. The aim was to assess the survival effect of adding to conventional androgen deprivation therapy (ADT) a potent hormone-suppressing drug, enzalutamide .

• Number of participants: 1068 patients at 244 centers in 17 countries.
• Arms: (1) Enzalutamide + Leuprolide, (2) Leuprolide alone, (3) Enzalutamide alone.
• High-risk definition: Patients with a PSA doubling time ≤9 months.
• Treatment plan: Treatment was suspended at week 37 in patients with PSA <0.2 ng/mL and restarted when PSA rose again.
• Primary objective: Metastasis-free survival (MFS), Secondary objectives: Overall survival (OS), time to new treatment and first skeletal event.

Results in Brief

After 8 years of follow-up, patients receiving enzalutamide + ADT had a risk of death that was 40% lower (HR 0.60). Adding the drug to conventional hormone suppression thus provided a significant long-term survival advantage.

Detailed Findings

Median follow-up: approximately 8 years (94 months). A total of 277 deaths were reported.

💬 DROZDOGAN Academy Commentary – What Does It Mean for Clinical Practice?

EMBARK answered a long-standing debate in prostate cancer treatment: “Is it too early to start treatment at the biochemical recurrence stage?” We now know that at this stage, the enzalutamide + ADT combination does more than lower PSA; in the long term, it also reduces the risk of death.

This result shows that the strategy of intensive AR pathway suppression in metastatic disease (as in trials such as LATITUDE or TITAN) should now be moved into earlier stages . Early intervention can significantly prolong survival, particularly in tumors with a PSA doubling time shorter than 9 months—that is, biologically “fast-moving” tumors.

The monotherapy arm is also noteworthy: although the OS difference was not statistically significant, it may be considered an option for some patients wishing to preserve quality of life and sexual function. However, this approach should be considered only in carefully selected, low-risk patients who can be closely monitored.

Clinically, this trial redefines PSA recurrence from a “silent laboratory finding” into a window of opportunity for early treatment . At this point, PSMA PET and similarly sensitive imaging methods, by detecting minimal metastatic burden, may further refine this strategy in the future.

In conclusion: EMBARK demonstrated that intensive androgen suppression before metastasis has not only biochemical, but also clinical significance . The treatment paradigm is increasingly evolving from “wait and see” to “early, targeted intervention.” This approach will reshape both clinical guidelines and patient management strategies in the coming years.

🛡️ Safety Profile

• Grade ≥3 adverse event rate: 52–57%.
• Treatment discontinuation: 27.5% (in the combination arm).
• Common effects: Hot flashes, fatigue, hypertension, musculoskeletal pain.
• Gynecomastia: Marked increase in the monotherapy arm.

No fatal adverse event was directly attributed to treatment.

⚠️ Limitations & Context

• During the trial, PSMA PET was not widely used; occult metastases may have been missed.
• The monotherapy arm was open-label; this could influence patient and physician behavior.
• Sponsor support: Supported by Pfizer & Astellas; disclosures were published in the journal.

🔭 Looking Ahead

In the future, early PSMA PET detection of metastases, AR pathway blockade concurrent with radiotherapy and individualized treatment intervals will be the focus of new research.

Source and Further Reading

• NEJM Original Article – Improved Survival with Enzalutamide in Biochemically Recurrent Prostate Cancer (October 19, 2025). Full text
• ClinicalTrials.gov: NCT02319837

Sponsor: Pfizer and Astellas Pharma. Conflict of interest disclosures are published on the journal page.