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Enzalutamide shines in nonmetastatic castration-resistant prostate cancer


 

REPORTING FROM GUCS 2018

Study details

Median metastasis-free survival in PROSPER was 36.6 months with enzalutamide and 14.7 months with placebo (hazard ratio, 0.29; P less than .0001), Dr. Hussain reported. Benefit was similar across a range of patient subgroups, including patients with PSA doubling times of less than and greater than 6 months.

Patients in the enzalutamide group had half the rate of progression events when compared with peers in the placebo group (23% vs. 49%). Among those with a metastasis-free survival event, the rate of deaths without documented radiographic progression after stopping study treatment was higher with enzalutamide (15% vs. 2%); there were somewhat more cardiovascular deaths with the drug within this subset, but no single cause was clearly predominant, she said.

Median time to PSA progression was 37.2 months with enzalutamide and merely 3.9 months with placebo (HR, 0.07; P less than .0001). Median time to first use of new antineoplastic therapy was 39.6 months and 17.7 months, respectively (HR, 0.21; P less than .0001).

Median overall survival was not yet reached in either group, but tended to be longer with enzalutamide (HR, 0.80).

“Therapy overall was well tolerated. Adverse events were generally consistent with those reported in prior clinical trials in men with castration-resistant disease,” Dr. Hussain said. The rate of grade 3 or worse events was 31% with enzalutamide and 23% with placebo. The enzalutamide group more commonly experienced grade 3 or worse hypertension (5% vs. 2%) and fatigue (3% vs. 1%).

The rate of adverse events leading to study discontinuation was 9% with enzalutamide and 6% with placebo, and that of death due to adverse events was 3% and 1%, respectively.

Dr. Hussain disclosed that she receives honoraria from OncLive; has a consulting or advisory role with Abbvie, Bayer, and Genentech/Roche; has patents, royalties, or other intellectual property pertaining to dual inhibition of MET and VEGF for the treatment of castration-resistant prostate cancer; and receives travel, accommodations, or expenses from Abbvie, Bayer, and Genentech. In addition, her institution receives research funding from AstraZeneca, Genentech, PCCTC, and Pfizer. The trial was sponsored by Pfizer, with collaboration of Astellas Pharma Inc. and Medivation LLC, a wholly owned subsidiary of Pfizer Inc.

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