Comparative efficacy of triptorelin pamoate and leuprolide acetate in men with advanced prostate cancer

OBJECTIVE: To compare the efficacy of monthly administrations of the luteinizing hormone-releasing hormone agonists triptorelin pamoate and leuprolide acetate to induce and maintain castrate levels of serum testosterone in men with advanced prostate cancer. PATIENTS AND METHODS: Men with advanced prostate cancer were randomly assigned to receive triptorelin 3.75 mg or leuprolide 7.5 mg. The agent was injected intramuscularly every 28 days for nine injections. Primary endpoints were the percentages of men whose serum testosterone concentrations declined to and were maintained at or below castrate levels (≤ 1.735 nmol/L or ≤500 ng/L) during 9 months (253 days) of treatment. Secondary endpoints were luteinizing hormone levels, bone pain, prostate specific antigen levels, quality of life, testosterone pharmacodynamics, survival, and safety variables. RESULTS: In all, 284 men received either triptorelin (140) or leuprolide (144). The percentage of men with castrate levels of serum testosterone was lower at 29 days for triptorelin than for leuprolide (91.2% vs 99.3%; point estimate -8.0, 95% confidence interval -16.9% to -1.4%), but equivalent at 57 days (97.7% vs 97.1%). The mean (98.8% vs 97.3%) and cumulative (96.2% vs 91.2%) castration maintenance rates between 29 and 253 days were equivalent between the treatment groups. Secondary endpoints were equivalent between treatment groups except for the 9-month survival rate, which was significantly higher for triptorelin than for leuprolide (97.0% vs 90.5%; P = 0.033). Both treatments were well tolerated. CONCLUSION: Triptorelin reduced testosterone concentrations less rapidly, but maintained castration as effectively as leuprolide. There was no evidence that the slower onset of castration caused deleterious effects.