Erleada May Extend Subsequent Progression in Men With Castration-Resistant Prostate Cancer

The addition of Erleada to androgen deprivation therapy (ADT) reduced the risk for death by 25% compared with placebo in patients with nonmetastatic castration-resistant prostate cancer, according to updated findings of the phase 3 SPARTAN trial that were presented at the 2019 European Society of Medical Oncology (ESMO) Congress.

“Collectively, these results further support apalutamide as a standard-of-care option for men with high-risk, nonmetastatic castration-resistant prostate cancer,” lead study author Dr. Matthew R. Smith, director of the Genitourinary Malignancies Program at the Massachusetts General Hospital Cancer Center, said during a presentation at the meeting.

In the international SPARTAN study, researchers compared the safety and efficacy of Erleada with placebo in 1,207 patients with nonmetastatic castration-resistant prostate cancer and a rapidly rising prostate-specific antigen (PSA) level, despite receiving continuous ADT.

The primary endpoint was metastasis-free survival (the time from treatment to developing metastases. Secondary endpoints included time to metastasis, progression-free survival (the time from treatment to disease worsening), time to symptomatic progression and overall survival. For patients who developed metastases, the researchers also evaluated the time between randomization to first treatment for metastatic castration-resistant prostate cancer and subsequent progression.

Erleada reduced the risk of metastasis or death by 72% in patients with nonmetastatic castration-resistant prostate cancer. The median metastasis-free survival was 40.5 months in the Erleada arm versus 16.2 months in the placebo arm.

At a median 41 months of follow-up, results showed that the median overall survival was not reached in either arm, favoring Erleada. Additional results showed that the four-year overall survival rates for the Erleada and placebo arms were 72.1% and 64.7%, respectively.

At the 20.3-month median follow-up, 61% of the Erleada arm remained on treatment compared with 30% of the placebo group. Additionally, at this first analysis, Erleada was found to improve the time to symptomatic progression compared with placebo.

Moreover, Erleada was also found to significantly extend subsequent progression after the first treatment compared with placebo (55.5 months and 43.8 months). Sixty-nine percent of those on the placebo arm and 40% of patients on Erleada received subsequent therapy, which mainly consisted of abiraterone acetate plus prednisone.

Grade 3/4 side effects were reported in 53.1% of patients on the Erleada arm and 36.7% of those on placebo, and serious side effects occurred in 33.5% and 24.9%, respectively.

Dr. Karim Fizazi, MD, PhD, commented on the overall survival following Smith’s presentation: “At the moment, we cannot say that apalutamide prolongs survival in this setting. (With extended subsequent progression), there is a more meaningful difference we are seeing; this is utterly important because abiraterone was provided as a potential salvage treatment in both arms. In other words, it is comparing deferred (androgen receptor}-targeting, at least in some patients, and at the same time, it is making a difference in (extending subsequent progression).”