Dataset Information

Post hoc analyses of East Asian patients from the randomized placebo-controlled PREVAIL trial of enzalutamide in patients with chemotherapy-naive, metastatic castration-resistant prostate cancer.

ABSTRACT:

Background

Enzalutamide is an androgen receptor (AR) inhibitor that acts on different steps in the AR signaling pathway. In PREVAIL, an international, phase III, double-blind, placebo-controlled trial, enzalutamide significantly reduced the risk of radiographic progression by 81% (hazard ratio [HR], 0.19; P < .0001) and reduced the risk of death by 29% (HR, 0.71; P < .0001) compared with placebo in chemotherapy-naïve men with metastatic castration-resistant prostate cancer.

Methods

To evaluate treatment effects, safety, and pharmacokinetics of enzalutamide in East Asian patients from the PREVAIL trial, we performed a post hoc analysis of the Japanese, Korean, and Singaporean patients. PREVAIL enrolled patients with asymptomatic or mildly symptomatic chemotherapy-naïve metastatic castration-resistant prostate cancer who had progressed on androgen deprivation therapy. During the study, patients received enzalutamide (160 mg/d) or placebo (1:1) until death or discontinuation because of radiographic progression or skeletal-related event and initiation of subsequent therapy. Centrally assessed radiographic progression-free survival (rPFS) and overall survival (OS) were coprimary endpoints. The secondary endpoints of the PREVAIL trial were investigator-assessed rPFS, time to initiation of chemotherapy, time to prostate-specific antigen (PSA) progression, and PSA response (≥50% decline).

Results

Of 1717 patients, 148 patients were enrolled at sites in East Asia (enzalutamide 73, placebo 75). Treatment effect of enzalutamide versus placebo was consistent with that for the overall population as indicated by the HRs (95% confidence interval) of 0.38 (0.10-1.44) for centrally assessed rPFS, 0.59 (0.29-1.23) for OS, 0.33 (0.19-0.60) for time to chemotherapy, and 0.32 (0.20-0.50) for time to PSA progression. In East Asian patients, PSA responses were observed in 68.5% and 14.7% of enzalutamide- and placebo-treated patients, respectively. The enzalutamide plasma concentration ratio (East Asian:non-Asian patients) was 1.12 (90% confidence interval, 1.05-1.20) at 13 weeks. Treatment-related adverse events grade ≥ 3 occurred in 1.4% and 2.7% of enzalutamide- and placebo-treated East Asian patients, respectively.

Conclusions

Treatment effects and safety of enzalutamide in East Asian patients were generally consistent with those observed in the overall study population from PREVAIL. CLINICALTRIALS.

Gov number

NCT01212991.

SUBMITTER: Kim CS

PROVIDER: S-EPMC5502144 | biostudies-literature | 2017 Jul

REPOSITORIES: biostudies-literature

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Post hoc analyses of East Asian patients from the randomized placebo-controlled PREVAIL trial of enzalutamide in patients with chemotherapy-naïve, metastatic castration-resistant prostate cancer.

Kim Choung Soo CS Choi Young Deuk YD Lee Sang Eun SE Lee Hyun Moo HM Ueda Takeshi T Yonese Junji J Fukagai Takashi T Chiong Edmund E Lau Weber W Abhyankar Sarang S Theeuwes Ad A Tombal Bertrand B Beer Tomasz M TM Kimura Go G

Medicine 20170701 27

<h4>Background</h4>Enzalutamide is an androgen receptor (AR) inhibitor that acts on different steps in the AR signaling pathway. In PREVAIL, an international, phase III, double-blind, placebo-controlled trial, enzalutamide significantly reduced the risk of radiographic progression by 81% (hazard ratio [HR], 0.19; P < .0001) and reduced the risk of death by 29% (HR, 0.71; P < .0001) compared with placebo in chemotherapy-naïve men with metastatic castration-resistant prostate cancer.<h4>Methods</h ...[more]

PMID: 28682871

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Project description:IntroductionEnzalutamide significantly improved clinical outcomes compared with placebo in patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC) with disease progression despite androgen deprivation therapy (ADT) in the PREVAIL study. However, few patients from Asia were enrolled. Our study (NCT02294461) aimed to evaluate the safety and efficacy of enzalutamide in this disease setting in patients in mainland China, Korea, Taiwan, and Hong Kong.MethodsIn this double-blind, phase III study, patients with asymptomatic/mildly symptomatic metastatic prostate cancer and disease progression despite ADT were randomized to enzalutamide (160 mg/day) or placebo. The primary endpoint was time to prostate-specific antigen (PSA) progression. Secondary endpoints included overall survival, radiographic progression-free survival, time to first skeletal-related event (SRE), time to initiation of cytotoxic chemotherapy, PSA response ≥ 50%, best overall soft-tissue response, and safety. Pre-planned interim analysis was scheduled following approximately 175 PSA-progression events (67% of targeted total of 261 events). An additional 5-year landmark analysis of overall survival, time to antineoplastic therapy, and safety was performed.ResultsThe double-blind study period was stopped after interim analysis owing to the benefit of enzalutamide over placebo. Overall, 388 patients were randomized (enzalutamide, n = 198; placebo, n = 190). Baseline characteristics were balanced between treatment groups. Enzalutamide significantly reduced risk of PSA progression vs placebo (hazard ratio 0.38; 95% CI 0.27-0.52; P < 0.0001). Median time to PSA progression was 8.31 months with enzalutamide and 2.86 months with placebo. Secondary endpoints, including 5-year overall survival, were significantly improved with enzalutamide, except time to first SRE. Adverse-event incidence was similar between enzalutamide and placebo. Fatigue was the most common drug-related adverse event in both treatment groups.ConclusionEnzalutamide significantly reduced risk of PSA progression, improved secondary efficacy endpoints, and was well tolerated in chemotherapy-naïve Asian patients with mCRPC with disease progression despite ADT.Trial registrationwww.Clinicaltrialsgov NCT02294461.

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Project description:The U.S. Food and Drug Administration approved enzalutamide for the treatment of patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). At the prespecified interim analysis, a statistically significant improvement in overall survival was demonstrated for patients in the enzalutamide arm compared with patients in the placebo arm. The overall benefit-risk profile supports the expanded indication for enzalutamide. On September 10, 2014, the U.S. Food and Drug Administration approved enzalutamide for the treatment of patients with chemotherapy-naïve metastatic castration-resistant prostate cancer (mCRPC). Enzalutamide was initially approved in 2012 for use in patients with mCRPC who had previously received docetaxel. The current approval was based on the results of a randomized, placebo-controlled, double-blind trial conducted in 1,717 asymptomatic or minimally symptomatic patients with chemotherapy-naïve mCRPC. Patients were assigned to receive either enzalutamide 160 mg or placebo orally once daily. The coprimary endpoints were overall survival (OS) and radiographic progression-free survival (rPFS), which was assessed by independent central radiology review. At the prespecified interim analysis, a statistically significant improvement in OS was demonstrated for patients in the enzalutamide arm compared with patients in the placebo arm (hazard ratio [HR], 0.71; 95% confidence interval [CI], 0.60-0.84). The median OS was 32.4 and 30.2 months in the enzalutamide and placebo arms, respectively. A statistically significant prolongation of rPFS was observed in patients in the enzalutamide arm (HR, 0.17; 95% CI, 0.14-0.21). In addition, the time to initiation of cytotoxic chemotherapy was prolonged in the enzalutamide arm (HR, 0.35; 95% CI, 0.30-0.40), with median times of 28.0 and 10.8 months in the enzalutamide and placebo arms, respectively. The safety profile was similar to that previously reported for enzalutamide. Adverse reactions of interest included seizure, hypertension, and falls. Enzalutamide should be discontinued if a seizure occurs during treatment. The overall benefit-risk profile supports the expanded indication for enzalutamide.

Project description:IntroductionProstate cancer (PC) is the second leading cause of cancer death among US men and accounts for considerable healthcare expenditures. We evaluated economic outcomes in men with chemotherapy-naïve metastatic castration-resistant PC (mCRPC) treated with enzalutamide or abiraterone acetate plus prednisone (abiraterone).MethodsWe performed a retrospective analysis on 3174 men (18 years or older) utilizing the Veterans Health Administration (VHA) database from 1 April 2014 to 31 March 2018. Men with mCRPC were included if they had at least one pharmacy claim for enzalutamide or abiraterone (first claim date = index date) following surgical or medical castration, had no chemotherapy treatment within 12 months prior to the index date, and had continuous VHA enrollment for at least 12 months pre- and post-index date. Men were followed until death, disenrollment, or end of study and were 1:1 propensity score matched (PSM). All-cause and PC-related resource use and costs per patient per month (PPPM) in the 12 months post index were compared between matched cohorts.ResultsWe identified 1229 men with mCRPC prescribed enzalutamide and 1945 prescribed abiraterone with mean ages of 74 and 73 years, respectively. After PSM, each cohort had 1160 patients. The enzalutamide cohort had fewer all-cause (2.51 vs 2.86; p < 0.0001) and PC-related outpatient visits (0.86 vs 1.03; p < 0.0001), with corresponding lower all-cause ($2588 vs $3115; p < 0.0001) and PC-related ($1356 vs $1775; p < 0.0001) PPPM outpatient costs compared with the abiraterone cohort. All-cause total costs (medical and pharmacy) PPPM ($8085 vs $9092; p = 0.0002) and PC-related total costs PPPM ($6321 vs $7280; p < 0.0001) were significantly lower in the enzalutamide cohort compared with the abiraterone cohort.ConclusionsEnzalutamide-treated men with chemotherapy-naïve mCRPC had significantly lower resource utilization and healthcare costs compared with abiraterone-treated men.