Immediate-onset systemic allergic reactions, some resulting in hypotension and syncope, have occurred after administration of Plenaxis®. These immediate-onset reactions have been reported to occur following any administration of Plenaxis®, including after the initial dose. The cumulative risk of such a reaction increases with the duration of treatment (see WARNINGS). Following each injection of Plenaxis®, patients should be observed for at least 30 minutes in the office and in the event of an allergic reaction, managed appropriately.
- Only physicians who have enrolled in the Plenaxis® PLUS Program (Plenaxis® User Safety Program), based on their attestation of qualifications and acceptance of prescribing responsibilities, may prescribe Plenaxis® (See DOSAGE AND ADMINISTRATION and HOW SUPPLIED).
- Plenaxis® is indicated for the palliative treatment of men with advanced symptomatic prostate cancer, in whom LHRH agonist therapy is not appropriate and who refuse surgical castration, and have one or more of the following: (1) risk of neurological compromise due to metastases, (2) ureteral or bladder outlet obstruction due to local encroachment or metastatic disease, or (3) severe bone pain from skeletal metastases persisting on narcotic analgesia.
- The effectiveness of Plenaxis® in suppressing serum testosterone to castrate levels decreases with continued dosing in some patients (see CLINICAL PHARMACOLOGY, Pharmacodynamics). Effectiveness beyond 12 months has not been established. Treatment failure can be detected by measuring serum total testosterone concentrations just prior to administration on Day 29 and every 8 weeks thereafter (see WARNINGS).
Abarelix for injectable suspension (Plenaxis®) is a synthetic decapeptide with potent antagonistic activity against naturally occurring gonadotropin releasing-hormone (GnRH).
Plenaxis® is indicated for the palliative treatment of men with advanced symptomatic prostate cancer, in whom LHRH agonist therapy is not appropriate and who refuse surgical castration, and have one or more of the following: (1) risk of neurological compromise due to metastases, (2) ureteral or bladder outlet obstruction due to local encroachment or metastatic disease, or (3) severe bone pain from skeletal metastases persisting on narcotic analgesia.
Media Articles Related to Plenaxis (Abarelix)
Prostate Cancer Mortality in Men With a Negative Initial Biopsy
Source: Medscape Pathology & Lab Medicine Headlines [2017.03.17]
Dr Chodak discusses the next steps for prostate cancer patients following a negative initial biopsy, based on 20 years of data analyzed in a recent population-based study of prostate cancer mortality risk.
Prostate Cancer and Vasectomy Not Linkedâ€¦But With One Caveat
Source: Medscape Hematology-Oncology Headlines [2017.03.16]
A new large study found no association between prostate cancer and vasectomy, except for a small increase in the risk for low-intermediate-grade disease.
Medscape Medical News
Metastases, Not Death, New Benchmark in Prostate Cancer?
Source: Medscape Hematology-Oncology Headlines [2017.03.16]
Prostate cancer experts argue in favor of changing the primary endpoint of active surveillance trials to metastatic disease to reflect what is clinically meaningful to men.
Medscape Medical News
Could antidepressants stop prostate cancer from spreading?
Source: Bones / Orthopedics News From Medical News Today [2017.03.13]
Researchers have discovered an enzyme that helps prostate cancer cells spread to the bone, but antidepressants may have the potential to halt this process.
New test distinguishes 'tigers' from 'pussycats' in prostate cancer
Source: Medical Devices / Diagnostics News From Medical News Today [2017.03.01]
A new test has been developed to make the vital distinction between aggressive and less harmful forms of prostate cancer, helping to avoid sometimes-damaging unnecessary treatment.
Published Studies Related to Plenaxis (Abarelix)
A phase 3, multicenter, open label, randomized study of abarelix versus leuprolide plus daily antiandrogen in men with prostate cancer. [2002.04]
PURPOSE: We compared the endocrinological and biochemical efficacy of abarelix depot, a gonadotropin-releasing hormone antagonist, with that of a widely used combination of luteinizing hormone releasing hormone agonist and a nonsteroidal antiandrogen... CONCLUSIONS: Abarelix as monotherapy achieves medical castration significantly more rapidly than combination therapy and avoids the testosterone surge characteristic of agonist therapy. Both treatments were equally effective in reducing serum prostate specific antigen, and achieving and maintaining castrate levels of testosterone.
A phase 3, multicenter, open-label, randomized study of abarelix versus leuprolide acetate in men with prostate cancer. [2001.11]
OBJECTIVES: To evaluate the levels of testosterone and other hormones in men with prostate cancer treated with abarelix versus leuprolide acetate... CONCLUSIONS: Treatment with abarelix produced a higher percentage of patients who avoided a testosterone surge and had a more rapid time to testosterone suppression with a higher rate of medical castration 1 day after treatment and greater reductions in testosterone, luteinizing hormone, follicle-stimulating hormone, and dihydrotestosterone during the first 2 weeks of treatment compared with leuprolide acetate. The achievement and maintenance of castration was comparable between the two groups.
Abarelix and other gonadotrophin-releasing hormone antagonists in prostate cancer. [2009.12]
Hormonal therapy is the main recommended treatment for locally advanced and metastatic prostate cancer... Clinical data on both abarelix and degarelix show that they can produce rapid and sustained decreases in testosterone to castrate levels without the need for co-administration of an antiandrogen, and with a very low complication rate in the short term.
Abarelix for injectable suspension: first-in-class gonadotropin-releasing hormone antagonist for prostate cancer. [2006.12]
Abarelix, a gonadotropin-releasing hormone antagonist, with its indication for advanced symptomatic prostate cancer, represents the newest category of hormonal therapy introduced in the past 15 years. Results from Phase II and III clinical trials demonstrate the advantages of abarelix over commonly used luteinizing hormone-releasing hormone (LHRH) agonist therapy: abarelix does not cause a surge in serum testosterone that can precipitate a flare phenomenon or worsening of disease, particularly dangerous for patients with metastatic, symptomatic disease, and produces medical castration more quickly...
Dose-escalated abarelix in androgen-independent prostate cancer: a phase I study. [2006.10]
Follicle-stimulating hormone has been shown to be a mitogen in preclinical models of androgen-independent prostate cancer and abarelix has been previously shown to significantly reduce follicle-stimulating hormone levels in patients when administered monthly... Treatment with biweekly abarelix in patients with androgen-independent prostate cancer is feasible with no unexpected toxicity, but fails to completely suppress serum follicle-stimulating hormone levels or produce prostate-specific antigen responses.
Clinical Trials Related to Plenaxis (Abarelix)
The Plenaxisďż˝ Experience Study [Suspended]
Praecis is currently conducting a 2000 patient Experience Study; this is a Phase IV
commitment postmarketing safety study in the Food and Drug Administration (FDA) indicated
population of patients receiving Plenaxis®. The purpose of the study is to estimate the
incidence of immediate-onset systemic allergic reactions in the indicated population
receiving Plenaxis® and to determine whether the hazard rate changes over time.
Abarelix Versus Goserelin Plus Bicalutamide in Patients With Advanced or Metastatic Prostate Cancer [Completed]
To compare the safety of efficacy of abarelix versus goserelin plus bicalutamide in patients
with advanced or metastatic prostate cancer.
Study of Abarelix in Androgen-Independent Prostate Cancer Progressing After Agonist Therapy [Completed]
This is a Phase 2, open-label study in subjects with androgen-independent prostate cancer
who have progressed following treatment with an LHRH agonist. Up to 22 subjects will be
enrolled. Enrollment will be monitored to ensure that not all subjects are enrolled based
on rising prostate specific antigen (PSA) criterion only.
Subjects will be treated with abarelix (Plenaxis) 100 mg intramuscularly (IM) every 2 weeks
for 12 weeks (total dose of 600 mg).
Page last updated: 2017-03-17