An open-label study of abarelix in men with symptomatic prostate cancer at risk of treatment with LHRH agonists.
OBJECTIVE
To evaluate the ability of abarelix, a gonadotropin-releasing hormone antagonist, to provide an alternative treatment to bilateral orchiectomy in men with advanced prostate cancer symptoms and to evaluate its safety, clinical and biochemical efficacy, and effects on prostate-specific antigen and serum hormone levels.


METHODS
For 168 days, 81 patients from 17 centers received monthly intramuscular injections of open-label abarelix 100 mg (at least one dose). Patients were evaluated for the avoidance of bilateral orchiectomy, efficacy, disease response, percentage of change in prostate-specific antigen level, change in the intensity of pain, neurologic compromise, and other efficacy variables. Safety was evaluated through reports of adverse events and abnormal laboratory values.


RESULTS
No patients required bilateral orchiectomy, but 2 patients were withdrawn from the study because of treatment-related events and were considered as failures to avoid orchiectomy. Treatment produced an 88% (38 of 43) objective response rate on day 85. Sixty-five (90%) of 72 patients experienced improvement in the pain score and/or analgesic use, urinary obstruction, urinary catheter removal, hydronephrosis, and/or azotemia. No patient with impending neurologic compromise at study entry developed spinal cord compression. The median reduction from the baseline prostate-specific antigen value was 75% on day 15 and greater than 95% from day 57 onward. Abarelix was well tolerated, and adverse events were the sequelae of advanced prostate cancer, comorbid medical disorders, or medical castration.


CONCLUSIONS
These results suggest that abarelix provides a safe and effective medical alternative to surgical castration in symptomatic patients with advanced prostate cancer without the risk of the clinical flare associated with luteinizing hormone-releasing hormone agonists.
Koch
Michael
M
Indiana University Medical Center, Indianapolis, Indiana, USA.
Steidle
Christopher
C
Brosman
Stanley
S
Centeno
Arthur
A
Gaylis
Franklin
F
Campion
Marilyn
M
Garnick
Marc B
MB
D000230:Adenocarcinoma / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D014408:Biomarkers, Tumor / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors*; D006727:Hormone Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000627:therapeutic use*; D010147:Pain Measurement; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000150:complications / Q000188:drug therapy*; D012449:Safety; D013739:Testosterone / Q000097:blood; D016896:Treatment Outcome; D001748:Urinary Bladder Neck Obstruction / Q000209:etiology
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D006727:Hormone Antagonists; D009842:Oligopeptides; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D017430:Prostate-Specific Antigen; C423508:abarelix