Dataset Information

Clinical Evaluation of Abiraterone in the Treatment of Metastatic Prostate Cancer.

ABSTRACT: Treatment of castration-resistant prostate cancer remains an area of unmet medical need. Evidence suggests that this entity continues to be driven by androgens and androgen receptor (AR) signaling. Abiraterone acetate, a pregnenolone derivative, is an oral selective and irreversible inhibitor of the key steroidogenic enzyme CYP17. It possesses dual 17-? hydroxylase and C17,20-lyase blocking activity, the result of which is decreased gonadal and extra-gonadal androgen synthesis. Abiraterone was first approved by the US Food and Drug Administration (FDA) in 2011 following the demonstration of superior survival compared with placebo in the post-docetaxel population. Since that time, more evidence has been generated from preclinical studies and clinical trials which have considerably enhanced our understanding of this complex disease. In this paper, we review the development of abiraterone acetate, its pharmacological characteristics, and its effects on the androgen-AR signaling axis, along with the combined experience from clinical trials. We also discuss some of the ongoing trials using this agent, as well as potential mechanisms of abiraterone resistance, novel bio-marker development, and future directions using AR-directed therapies.

SUBMITTER: Goyal J

PROVIDER: S-EPMC3904375 | biostudies-literature | 2013 Jul

REPOSITORIES: biostudies-literature

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Clinical Evaluation of Abiraterone in the Treatment of Metastatic Prostate Cancer.

Goyal Jatinder J Antonarakis Emmanuel S ES

Clinical medicine insights. Urology 20130701 7

Treatment of castration-resistant prostate cancer remains an area of unmet medical need. Evidence suggests that this entity continues to be driven by androgens and androgen receptor (AR) signaling. Abiraterone acetate, a pregnenolone derivative, is an oral selective and irreversible inhibitor of the key steroidogenic enzyme CYP17. It possesses dual 17-α hydroxylase and C17,20-lyase blocking activity, the result of which is decreased gonadal and extra-gonadal androgen synthesis. Abiraterone was f ...[more]

PMID: 24482578

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Project description:Androgen deprivation therapy remains the single most effective treatment for the initial therapy of advanced prostate cancer, but is uniformly marked by progression to castration-resistant prostate cancer (CRPC). Residual tumor androgens and androgen axis activation are now recognized to play a prominent role in mediating CRPC progression. Despite suppression of circulating testosterone to castrate levels, castration does not eliminate androgens from the prostate tumor microenvironment and residual androgen levels are well within the range capable of activating the androgen receptor (AR) and AR-mediated gene expression. Accordingly, therapeutic strategies that more effectively target production of intratumoral androgens are necessary. The introduction of abiraterone, a potent suppressor of cytochrome P450 17 α-hydroxysteroid dehydrogenase-mediated androgen production, has heralded a new era in the hormonal treatment of men with metastatic CRPC. Herein, the androgen and AR-mediated mechanisms that contribute to CRPC progression and establish cytochrome P450 17 α-hydroxysteroid dehydrogenase as a critical therapeutic target are briefly reviewed. The mechanism of action and pharmacokinetics of abiraterone are reviewed and its recently described activity against AR and 3-β-hydroxysteroid dehydrogenase is discussed. The Phase I and II data initially demonstrating the efficacy of abiraterone and Phase III data supporting its approval for patients with metastatic CRPC are reviewed. The safety and tolerability of abiraterone, including the incidence and management of side effects and potential drug interactions, are discussed. The current place of abiraterone in CRPC therapy is reviewed and early evidence regarding cross-resistance of abiraterone with taxane therapy, mechanisms of resistance to abiraterone, and observations of an abiraterone withdrawal response are presented. Future directions in the use of abiraterone, including optimal dosing strategies, the role of abiraterone in earlier disease settings, including castration sensitive, biochemically recurrent, or localized disease, and the rationale for combinatorial treatment strategies of abiraterone with enzalutamide and other targeted agents are also discussed.

Project description:PurposeMetastatic castration-resistant prostate cancer (mCRPC) remains a lethal disease with current standard-of-care therapies. Homologous recombination repair (HRR) gene alterations, including BRCA1/2 alterations, can sensitize cancer cells to poly (ADP-ribose) polymerase inhibition, which may improve outcomes in treatment-naïve mCRPC when combined with androgen receptor signaling inhibition.MethodsMAGNITUDE (ClinicalTrials.gov identifier: NCT03748641) is a phase III, randomized, double-blinded study that evaluates niraparib and abiraterone acetate plus prednisone (niraparib + AAP) in patients with (HRR+, n = 423) or without (HRR-, n = 247) HRR-associated gene alterations, as prospectively determined by tissue/plasma-based assays. Patients were assigned 1:1 to receive niraparib + AAP or placebo + AAP. The primary end point, radiographic progression-free survival (rPFS) assessed by central review, was evaluated first in the BRCA1/2 subgroup and then in the full HRR+ cohort, with secondary end points analyzed for the full HRR+ cohort if rPFS was statistically significant. A futility analysis was preplanned in the HRR- cohort.ResultsMedian rPFS in the BRCA1/2 subgroup was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.6 v 10.9 months; hazard ratio [HR], 0.53; 95% CI, 0.36 to 0.79; P = .001). In the overall HRR+ cohort, rPFS was significantly longer in the niraparib + AAP group compared with the placebo + AAP group (16.5 v 13.7 months; HR, 0.73; 95% CI, 0.56 to 0.96; P = .022). These findings were supported by improvement in the secondary end points of time to symptomatic progression and time to initiation of cytotoxic chemotherapy. In the HRR- cohort, futility was declared per the prespecified criteria. Treatment with niraparib + AAP was tolerable, with anemia and hypertension as the most reported grade ≥ 3 adverse events.ConclusionCombination treatment with niraparib + AAP significantly lengthened rPFS in patients with HRR+ mCRPC compared with standard-of-care AAP.[Media: see text].

Project description:IntroductionRadium-223, abiraterone, and enzalutamide have each been shown to significantly improve survival as monotherapy in patients with metastatic castration-resistant prostate cancer. However, effects of combination radium-223 plus abiraterone or enzalutamide on survival and safety remain unclear.Patients and methodsThis single-center retrospective cohort study used electronic health record data of patients with metastatic castration-resistant prostate cancer and bone metastases who were treated with radium-223 between April 1, 2014 and February 19, 2019. Patients who received radium-223 monotherapy were compared to patients who received a combination of radium-223 plus either abiraterone or enzalutamide. The primary endpoint was overall survival. Secondary endpoints included progression-free survival, time to symptomatic skeletal event, symptomatic skeletal event-free survival, and incidence of drug-related adverse events. Time-to-event analyses were estimated by log rank tests using Kaplan-Meier curves. Hazard ratios and 95% confidence intervals were derived from Cox proportional hazards models. Chi-square tests evaluated difference in serious adverse events between the two arms.ResultsA total of 60 patients met inclusion criteria (n = 41 in the monotherapy arm, n = 19 in the combination arm). Differences in median overall survival were not observed (12.7 vs. 12.8 months; HR 1.15, 95% CI 0.59-2.23; P = 0.68), but median progression-free survival was significantly longer in the combination arm (7.6 vs. 4.9 months; HR 1.94, 95% CI 1.11-3.40; P = 0.02). Significant differences were not observed in time to first SSE (P = 0.97), SSE-free survival (P = 0.16), or in the overall incidence of serious adverse events (P = 0.45).ConclusionCombination radium-223 plus abiraterone or enzalutamide did not improve overall survival, but prolonged progression-free survival without increasing the incidence of serious adverse events in metastatic castration-resistant prostate cancer patients with bone metastases. However, these results are limited by small numbers and patient selection inherent in retrospective analysis.

Dataset Information

Clinical Evaluation of Abiraterone in the Treatment of Metastatic Prostate Cancer.

Publications

Clinical Evaluation of Abiraterone in the Treatment of Metastatic Prostate Cancer.

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