EMBARK: Post Hoc Analysis of Impact of Treatment Suspension on HRQOL

Stephen J. Freedland, MD, of Cedars-Sinai Medical Center, and colleagues involved in the phase 3 EMBARK study attempted to confirm whether treatment suspension for these patients may lead to improvements in health-related quality of life (HRQOL).

Their findings are being presented at the 2024 American Society of Clinical Oncology Annual Meeting.

Previous readouts of the EMBARK study showed that enzalutamide plus leuprolide and enzalutamide monotherapy delayed metastasis-free survival compared with placebo plus leuprolide, while maintaining high HRQOL, in patients with high-risk biochemically recurrent nonmetastatic hormone-sensitive prostate cancer. Treatment was suspended at week 37 if patient prostate-specific antigen (PSA) levels dropped to lower than 0.2 ng/mL and was reinstated if PSA levels rose to at least 2.0 ng/mL with radical prostatectomy or at least 5.0 ng/mL without radical prostatectomy.

To determine HRQOL after treatment suspension, Dr. Freedland and colleagues assessed longitudinal change in HRQOL from new baseline—time of treatment suspension (week 37)—to subsequent assessments until week 205.

They found that treatment was suspended in 90.9%, 85.9%, and 67.8% of patients treated with enzalutamide plus leuprolide, enzalutamide monotherapy, and placebo plus leuprolide, respectively. A trend toward HRQOL improvement was found after treatment suspension in all 3 treatment arms, which often reached the clinically meaningful threshold at week 205.

Dr. Freedland and colleagues noted that after treatment suspension, all treatment arms reached clinically meaningful improvement in hormonal treatment side effects at the subsequent assessments of week 49 to week 97. However, these patients slowly deteriorated, with clinically meaningful deterioration at week 205 relative to week 37 in the enzalutamide-plus-leuprolide arm as well as the placebo-plus-leuprolide arm.

No statistically significant differences were observed between arms in change from week 37 to week 205, they added.

“This post hoc analysis confirmed that treatment suspension, as expected, leads to clinically meaningful improvements in HRQOL,” study authors concluded.