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)
Advances in Prostate Cancer: 2014
Source: Medscape Family Medicine Headlines [2014.12.11]
Dr Chodak highlights new findings in prostate cancer prevention, detection, and treatment in this 2014 update.
Prostate Cancer Overtreated Despite Limited Life Expectancy
Source: Medscape Medical Students Headlines [2014.12.11]
Surgery and radiation are being overused in men with prostate cancer and a life expectancy of less than 10 years, when less aggressive strategies would be more appropriate.
Medscape Medical News
No Prostate Cancer Risk With Testosterone for Hypogonadism
Source: Medscape Diabetes & Endocrinology Headlines [2014.12.10]
New registry data should help reassure doctors that using testosterone therapy for hypogonadism does not increase the risk for prostate cancer, say German researchers.
Medscape Medical News
A yardstick to measure the malignancy of prostate cancer
Source: Prostate / Prostate Cancer News From Medical News Today [2014.12.10]
A protein that influences the epigenetic characteristics of tumor cells is directly linked to the grade of malignancy of prostate cancer.
Prevention of prostate cancer growth and spread achieved in animal studies
Source: Genetics News From Medical News Today [2014.12.09]
Researchers at Georgetown Lombardi Comprehensive Cancer Center have completed a critical step in the journey from a basic science discovery in the lab to a potential clinical application, showing...
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 Plenaxis® 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.
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: 2014-12-11