A 12-Month Clinical Study of LA-2585 (45.0 MG): A New 6-Month Subcutaneous Delivery System for Leuprolide Acetate for the Treatment of Prostate Cancer

PurposeThe safety, efficacy and pharmacokinetics of LA-2585, a new 6-month subcutaneous depot of leuprolide acetate (Atrix Laboratories, Fort Collins, Colorado) were investigated in patients with prostate cancer.Materials and MethodsIn this 12-month, open label, multicenter study 111 patients with adenocarcinoma of the prostate were administered 45.0 mg LA-2585 subcutaneously once every 6 months. The primary efficacy parameter was serum testosterone 50 ng/dl or less. Leuprolide acetate pharmacokinetics were analyzed in a subset of 28 patients.ResultsOf the 111 enrolled patients 103 (93%) completed the 12-month study. Eight patients withdrew due to nonmedical reasons in 1, disease progression in 5 and cardiovascular disease in 2. By day 28, 108 of the 109 remaining patients (99%) achieved testosterone suppression, while 1 who never attained suppression was withdrawn at day 85. Mean time to castrate suppression was 21.2 days (median 21). At study completion 102 of 103 patients (99%) were below medical castrate testosterone levels of 50 ng/dl (mean ± SE 12.3 ± 2.1 ng/dl) with 91 of 103 (88%) at less than 20 ng/dl. Mean luteinizing hormone decreased from 6.98 ± 0.48 mIU/ml at baseline to 0.23 ± 0.14 mIU/ml at month 12. Luteinizing hormone was consistently below 1 mIU/ml. Mean prostate specific antigen decreased 97% from 39.8 ± 21.5 ng/ml at baseline to 1.2 ± 0.3 ng/ml at 12 months. No clinically significant flare reactions were observed. The most common treatment related adverse event was mild to moderate hot flashes.ConclusionsLA-2585 (45.0 mg depot) consistently produced and maintained safe and effective serum testosterone suppression with total serum testosterone well below the medical castrate level of less than 50 ng/dl.