ANAHEIM, California—Abarelix, an injectable gonadotropin-releasing hormone (GnRH) antagonist, reduces serum prostate-specific antigen (PSA) levels and testosterone levels more than standard therapy, with less hormonal "surge," according to several studies presented at the American Urological Association (AUA) annual meeting.
Abarelix depot is currently under priority review by the FDA for the treatment of prostate cancer. "Abarelix represents a completely unique hormonal therapy for prostate cancer. It is rapid acting, without a testosterone surge," commented Dennis Pessis, MD, associate professor of urology, Rush-Presbyterian-St. Luke’s Medical Center, Chicago. Dr. Pessis reported the findings for the Abarelix Study Group.
No Need for Combination Therapy
Antiandrogens are frequently coadministered with luteinizing hormone-releasing hormone (LHRH) agonists to mitigate the effects of the androgen and gonadotropin surge and the consequent potential clinical flare associated with the use of LHRH agonists alone.
Abarelix monotherapy is devoid of this initial surge and, therefore, could potentially eliminate the cost, noncompliance, and inconvenience associated with combined therapies, Dr. Pessis pointed out.
At the meeting, he reported the results of a head-to-head phase III trial (abstract 685) of 251 early- and late-stage prostate cancer patients randomized to abarelix (n = 168) or leuprolide acetate (Lupron) plus bicalutamide(Drug information on bicalutamide) (Casodex) (n = 83) for 24 weeks. Abarelix and the leuprolide combination were administered every 4 weeks by intramuscular injection, with an additional injection of abarelix given on day 15.
Serum levels of testosterone, dihydrotestosterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured throughout the course of the study.
