EMBARK Trial: Testosterone Levels Recover in Most Men After Prostate Cancer Treatment Suspension

A post hoc analysis of the phase 3 EMBARK trial has demonstrated that the majority of men with high-risk biochemically recurrent prostate cancer (搜索)搜索该疾病 achieve full testosterone查看药品详情 recovery following treatment suspension, according to findings presented at the 2025 American Urological Association Annual Meeting in Las Vegas.

The analysis, presented by Dr. Stephen J. Freedland, professor of urology at Cedars-Sinai查看公司主页 in Los Angeles, examined testosterone查看药品详情 recovery kinetics in patients who received either enzalutamide查看药品详情 (Xtandi查看药品详情) plus leuprolide acetate查看药品详情 or placebo plus leuprolide acetate and had their treatment suspended after achieving good PSA responses.

"One of the unique aspects of EMBARK was that after 9 months of treatments, PSA was measured, and if patients got a really good PSA response—less than 0.2 [ng/mL]—treatment was suspended," explained Dr. Freedland. "We know ongoing castration/low testosterone查看药品详情 levels can impact quality of life and lead to other poor outcomes."

Testosterone Recovery Rates and Timing

The analysis revealed that more than 80% of patients in both treatment groups achieved full testosterone查看药品详情 recovery (defined as >175 ng/dL) after treatment suspension. Remarkably, over 98% of patients experienced at least partial recovery, with only 2% or fewer showing no recovery at all.

The median time to first occurrence of testosterone查看药品详情 recovery was 8.3 months (range, 0-36.0 months) in the enzalutamide查看药品详情 plus leuprolide acetate查看药品详情 arm compared to 5.9 months (range, 0-47.1 months) in the placebo plus leuprolide arm. The mean recovery times were 8.9 months and 8.0 months, respectively.

Age-Related Differences in Recovery

When stratified by age, the analysis showed important differences between younger and older men:

• For men under 70 years: 89% in the enzalutamide查看药品详情 plus leuprolide group and 92% in the placebo plus leuprolide group achieved full testosterone查看药品详情 recovery. Notably, all patients in this younger age group showed at least some testosterone recovery.

• For men 70 years or older: 78% in the enzalutamide查看药品详情 plus leuprolide group and 84% in the placebo plus leuprolide group achieved full recovery.

"Importantly, no patients in the younger age group had no recovery at all," Dr. Freedland emphasized during his presentation.

EMBARK Trial Design and Patient Population

The EMBARK trial enrolled patients with prostate cancer (搜索)搜索该疾病 who had high-risk biochemical recurrence, characterized by:

• PSA level of at least 1 ng/mL after radical prostatectomy or at least 2 ng/mL above the nadir for primary external beam radiation therapy
• PSA doubling time of 9 months or less
• No metastases on bone scan or CT/MRI
• Baseline testosterone level of at least 150 ng/dL

Patients were randomized 1:1:1 to receive enzalutamide查看药品详情 plus leuprolide acetate查看药品详情, placebo plus leuprolide acetate, or enzalutamide monotherapy. The primary endpoint was metastasis-free survival for the combination therapy versus leuprolide alone.

At the 36-week mark, patients whose PSA levels dropped below 0.2 ng/mL had their treatment suspended, and testosterone查看药品详情 levels were subsequently measured every 12 weeks.

Clinical Implications

These findings have significant implications for prostate cancer (搜索)搜索该疾病 treatment strategies, particularly regarding intermittent hormone therapy approaches. The high rates of testosterone查看药品详情 recovery suggest that temporary hormone therapy suspension may be a viable strategy to improve quality of life while maintaining treatment efficacy.

"In summary, what we showed is EMBARK, for those who got to the treatment suspension—which was the majority of patients—that with time, the testosterone查看药品详情 recovers...and the vast majority of patients do ultimately develop return of testosterone," Dr. Freedland concluded.

The results provide reassurance to clinicians and patients that testosterone查看药品详情 levels can recover after androgen deprivation therapy, potentially reducing long-term side effects associated with continuous hormone suppression while still effectively managing prostate cancer (搜索)搜索该疾病.