Leuprolide acetate (30-mg depot every four months) in the treatment of advanced prostate cancer

Objectives. An unblinded, multicenter study to evaluate the efficacy and safety of a long-acting depot formulation of leuprolide (30 mg injected intramuscularly every 16 weeks) was carried out in 49 patients with Stage D2 prostate cancer. Methods. Clinical evaluations were performed every 16 weeks, and serum testosterone levels were monitored biweekly or weekly for 32 weeks. Results. The mean serum testosterone level for the 45 evaluable patients fell to the castrate range (50 ng/dL or less) by week 3 after the initial depot injection and remained at that level throughout the initial 32-week treatment period. The median time to the onset of castrate levels was 22 days (range 9 to 43). Onset of castrate levels of testosterone was achieved within 4 weeks of the initial depot injection in 96% of patients. One patient (2%) experienced a transient "escape" (testosterone levels greater than 50 ng/dL on two consecutive determinations). Delay of an injection by up to 3 weeks did not have an effect on testosterone suppression. Objective tumor response (no progression) occurred in 90% of patients at week 16 and in 80% at week 32. Prostate-specific antigen and prostatic acid phosphatase decreased by 50% or more at week 52 in 97% and 76% of patients, respectively. Assessment of local disease status and overall performance status showed improvement or stability in most patients. The most common adverse events were hot flashes (45%), back pain (16%), and arthralgia (14%). Conclusions. The 30-mg depot formulation of leuprolide, which acts in a manner similar to the 7.5- and 22.5-mg depot formulations (given monthly and every 3 months, respectively) is effective in lowering serum testosterone to castrate levels in all patients and demonstrates a favorable response in 80% of the patients with advanced prostate cancer for the 32-week observation period. The drug was well tolerated in all patients. (C) 1998, Elsevier Science Inc. All rights reserved.