The gonadotropin-releasing hormone antagonist abarelix depot versus luteinizing hormone releasing hormone agonists leuprolide or goserelin: Initial results of endocrinological and biochemical efficacies in patients with prostate cancer
K. Tomera et al., The gonadotropin-releasing hormone antagonist abarelix depot versus luteinizing hormone releasing hormone agonists leuprolide or goserelin: Initial results of endocrinological and biochemical efficacies in patients with prostate cancer, J UROL, 165(5), 2001, pp. 1585-1589
Purpose: We contrasted the endocrinological and biochemical efficacies of a
barelix depot, a pure gonadotropin-releasing hormone antagonist, with a pro
spective concurrent control cohort receiving luteinizing hormone releasing
hormone (LH-RH) agonists with or without antiandrogen for treatment of pati
ents with prostate cancer receiving initial hormonal therapy.
Materials and Methods: In this phase 2 open label study 242 patients with p
rostate cancer requiring initial hormonal treatment received abarelix depot
(209) or LH-RH agonists (33) with or without antiandrogen. A total of 100
mg. abarelix depot was delivered intramuscularly every 28 days with an addi
tional injection on day 15. LH-RH agonists with or without antiandrogen wer
e administered according to the depot formulation used. Endocrine efficacy
was measured by the absence of testosterone surge and rapidity of castratio
n onset. The rate of prostate specific antigen decrease was assessed.
Results: No patient treated with abarelix depot had testosterone surge duri
ng week 1 compared with 82% of those treated with LH-RH agonists. The conco
mitant administration of antiandrogen had no effect. During the first week
of drug administration, in 75% of patients treated with abarelix depot and
in 0% of those treated with LH-RH agonist medical castration was achieved.
Prostate specific antigen decrease was faster, with no flare or surge in pa
tients treated with abarelix depot. Abarelix depot was well tolerated.
Conclusions: Abarelix depot represents a new class of hormonal therapy, gon
adotropin releasing hormone antagonists, that has rapid medical castration
and avoids the testosterone surge characteristic of LH-RH agonists.