Dataset Information

Enzalutamide in Men with Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer: Extended Analysis of the Phase 3 PREVAIL Study.

ABSTRACT: Enzalutamide significantly improved radiographic progression-free survival (rPFS) and overall survival (OS) among men with chemotherapy-naïve metastatic castration-resistant prostate cancer at the prespecified interim analysis of PREVAIL, a phase 3, double-blind, randomized study. We evaluated the longer-term efficacy and safety of enzalutamide up to the prespecified number of deaths in the final analysis, which included an additional 20 mo of follow-up for investigator-assessed rPFS, 9 mo of follow-up for OS, and 4 mo of follow-up for safety. Enzalutamide reduced the risk of radiographic progression or death by 68% (hazard ratio [HR] 0.32, 95% confidence interval [CI] 0.28-0.37; p<0.0001) and the risk of death by 23% (HR 0.77, 95% CI 0.67-0.88; p=0.0002). Median investigator-assessed rPFS was 20.0 mo (95% CI 18.9-22.1) in the enzalutamide arm and 5.4 mo (95% CI 4.1-5.6) in the placebo arm. Median OS was 35.3 mo (95% CI 32.2-not yet reached) in the enzalutamide arm and 31.3 mo (95% CI 28.8-34.2) in the placebo arm. At the time of the OS analysis, 167 patients in the placebo arm had crossed over to receive enzalutamide. The most common adverse events in the enzalutamide arm were fatigue, back pain, constipation, and arthralgia. This final analysis of PREVAIL provides more complete assessment of the clinical benefit of enzalutamide. PREVAIL is registered on ClinicalTrials.gov as NCT01212991.According to data from longer follow-up, enzalutamide continued to provide benefit over placebo in patients with metastatic castration-resistant prostate cancer.

SUBMITTER: Beer TM

PROVIDER: S-EPMC5570461 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature

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Enzalutamide in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer: Extended Analysis of the Phase 3 PREVAIL Study.

Beer Tomasz M TM Armstrong Andrew J AJ Rathkopf Dana D Loriot Yohann Y Sternberg Cora N CN Higano Celestia S CS Iversen Peter P Evans Christopher P CP Kim Choung-Soo CS Kimura Go G Miller Kurt K Saad Fred F Bjartell Anders S AS Borre Michael M Mulders Peter P Tammela Teuvo L TL Parli Teresa T Sari Suha S van Os Steve S Theeuwes Ad A Tombal Bertrand B

European urology 20160728 2

Enzalutamide significantly improved radiographic progression-free survival (rPFS) and overall survival (OS) among men with chemotherapy-naïve metastatic castration-resistant prostate cancer at the prespecified interim analysis of PREVAIL, a phase 3, double-blind, randomized study. We evaluated the longer-term efficacy and safety of enzalutamide up to the prespecified number of deaths in the final analysis, which included an additional 20 mo of follow-up for investigator-assessed rPFS, 9 mo of fo ...[more]

PMID: 27477525

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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.

Project description:BackgroundEnzalutamide 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.MethodsTo 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).ResultsOf 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.ConclusionsTreatment effects and safety of enzalutamide in East Asian patients were generally consistent with those observed in the overall study population from PREVAIL. CLINICALTRIALS.Gov numberNCT01212991.

Project description:BackgroundWe aimed to evaluate cost-effectiveness of enzalutamide in chemotherapy-naïve metastatic castration-resistant prostate cancer patients in Japan.MethodsA Markov model was developed to capture time spent by patients in various health states: stable, progression and death. Abiraterone acetate and docetaxel were set as active comparators. Clinical outcomes were obtained from the PREVAIL, COU-AA-302 and TAX327 trials. Treatment sequence, concomitant drugs and therapies for adverse events were estimated from responses to a survey by 14 Japanese prostate cancer experts. The analytic perspective was public healthcare payer, with a 10-year time horizon. The incremental cost-effectiveness ratio was estimated from quality-adjusted life-years and Japanese public healthcare costs. Probabilistic sensitivity analysis was performed to assess the robustness of the findings.ResultsAccording to the survey, the most common treatment sequences were (i) enzalutamide → docetaxel → cabazitaxel (enzalutamide-first sequencing), (ii) abiraterone → enzalutamide → docetaxel (abiraterone-first sequencing) and (iii) docetaxel→ enzalutamide → cabazitaxel (docetaxel-first sequencing). In the base-case analysis, enzalutamide-first sequencing saved 1.74 million Japanese Yen versus abiraterone-first sequencing, with a 0.129 quality-adjusted life-year gain (dominant). Enzalutamide-first sequencing had a cost increase of 4.44 million Japanese Yen over docetaxel-first sequencing, with a 0.371 quality-adjusted life-years gain. The incremental cost-effectiveness ratio of enzalutamide-first sequencing versus docetaxel-first sequencing was estimated as 11.94 million Japanese Yen/quality-adjusted life-years. Probabilistic sensitivity analyses demonstrated that, compared with abiraterone-first sequencing, enzalutamide-first sequencing had an 87.4% probability of being dominant.ConclusionsResults modeled herein suggest that the enzalutamide-first sequencing is more cost-effective than the abiraterone-first sequencing, but less cost-effective than docetaxel-first sequencing for chemotherapy-naïve patients with metastatic castration-resistant prostate cancer.

Project description:ObjectiveEvaluation of the comparative effectiveness of enzalutamide and abiraterone in patients with metastatic castration-resistant prostate cancer (mCRPC) is limited to meta-analyses of randomized trials that exclude patients with significant comorbidities. We evaluated overall survival (OS) in patients with chemotherapy-naive mCRPC treated with enzalutamide or abiraterone acetate (abiraterone) in a real-world single payer setting.MethodsA retrospective analysis (4/1/2014-3/31/2018) of the Veterans Health Administration (VHA) database was conducted. Patients with mCRPC had ≥1 pharmacy claim for enzalutamide or abiraterone (first claim date = index date) following disease progression on surgical/medical castration, without chemotherapy <12 months prior to index date. Patients had continuous VHA enrollment for ≥12 months pre-index date and were followed until death, disenrollment, or end of study. Kaplan-Meier analysis and multivariable Cox proportional hazards regression models examined the OS treatment effect.ResultsPatients with chemotherapy-naive mCRPC (N = 3174; enzalutamide, n = 1229; abiraterone, n = 1945) had mean ages of 74 and 73 years, respectively. Median follow-up was 18.27 and 19.07 months with enzalutamide and abiraterone, respectively. Enzalutamide-treated patients had longer median treatment duration than abiraterone-treated patients (9.93 vs 8.47 months, respectively, p = 0.0008). After baseline comorbidity adjustment, enzalutamide-treated patients had a 16% reduced risk of death (hazard ratio [HR] = 0.84; 95% CI, 0.76-0.94; p = 0.0012). For patients who remained on first line-therapy only, enzalutamide-treated patients had improved OS versus abiraterone-treated patients (HR = 0.71; 95% CI, 0.62-0.82). Enzalutamide-treated patients who crossed over to abiraterone had a comparable risk of death versus abiraterone-treated patients who crossed over to enzalutamide (HR = 1.10; 95% CI, 0.89-1.35). These results were confirmed by sensitivity analysis, which considered prognostic variables.ConclusionsRetrospective analysis of the VHA database indicated that chemotherapy-naive patients with mCRPC initiating therapy with enzalutamide had improved survival versus abiraterone.

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.

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.

Dataset Information

Enzalutamide in Men with Chemotherapy-naive Metastatic Castration-resistant Prostate Cancer: Extended Analysis of the Phase 3 PREVAIL Study.

Publications

Enzalutamide in Men with Chemotherapy-naïve Metastatic Castration-resistant Prostate Cancer: Extended Analysis of the Phase 3 PREVAIL Study.

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