Urology 2000 May;55(5):639-42
Evaluation of an implant that delivers leuprolide for 1 year for the palliative treatment of prostate cancer.
Fowler JE, Flanagan M, Gleason DM, Klimberg IW, Gottesman JE, Sharifi R
OBJECTIVES: 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.
PMID: 10792069, UI: 20253480