Evaluation of an implant that delivers leuprolide for 1 year for the palliative treatment of prostate cancer.
OBJECTIVE
To evaluate the Viadur implant, which delivers leuprolide acetate for the palliative treatment of advanced prostate cancer.


METHODS
Inserted subcutaneously, the 4 x 45-mm implant uses osmotic pressure to deliver leuprolide continuously at a controlled rate for 1 year. This 19-center open-label study enrolled patients with prostate cancer who had had no prior therapy or showed biochemical evidence of treatment failure after prostatectomy or radiotherapy. Each patient received one implant. After 1 year, that implant was removed, another was inserted, and patients were followed up for 2 additional months. The primary efficacy measure was suppression of testosterone to less than the castrate threshold (50 ng/dL).


RESULTS
Eighty patients were enrolled. The implant effectively suppressed testosterone in 79 patients (99%) within 2 to 4 weeks and maintained that suppression through the study period. In 1 patient, the testosterone was suppressed to less than 100 ng/dL within 4 weeks but was not less than 50 ng/dL until week 24. Prostate-specific antigen levels normalized (4 ng/mL or less) or a clinically significant decrease occurred in all patients. Leuprolide was rapidly absorbed, resulting in mean serum concentrations of 16.8 ng/mL 4 hours after implant insertion and 2.4 ng/mL at 24 hours; steady mean serum leuprolide concentrations were then maintained throughout the year, at approximately 0.9 ng/mL. Investigators were satisfied with the insertion and removal procedures. All patients reported satisfaction after 1 year of treatment. The safety profile of the implant was consistent with androgen ablation therapy. Most adverse events were mild, and the most common event was hot flashes.


CONCLUSIONS
The leuprolide implant effectively suppressed testosterone concentrations to less than the castrate threshold and maintained that suppression throughout the study period.
Fowler
J E
JE
University of Mississippi Medical Center, Jackson, Mississippi 39216, USA.
Flanagan
M
M
Gleason
D M
DM
Klimberg
I W
IW
Gottesman
J E
JE
Sharifi
R
R
D000368:Aged; D000369:Aged, 80 and over; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000009:adverse effects; D004343:Drug Implants; D005500:Follow-Up Studies; D006801:Humans; D016729:Leuprolide / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D010166:Palliative Care; D011471:Prostatic Neoplasms / Q000097:blood / Q000188:drug therapy*; D013739:Testosterone / Q000097:blood; D013997:Time Factors
D018931:Antineoplastic Agents, Hormonal; D004343:Drug Implants; D013739:Testosterone; D016729:Leuprolide