Clinical study results of the new formulation leuprorelin acetate three-month depot for the treatment of advanced prostate carcinoma.

Androgen suppression, using gonadotrophin-releasing hormone analogues (leuprorelin), is being developed as an effective treatment of advanced prostate carcinoma. Treatment with leuprorelin acetate 1-month depot is already well established all over the world. In order to increase patients' acceptability of this treatment, by reducing frequency of administration, a 3-month depot formulation has been developed in Takeda's research laboratories. A single-shot pharmacokinetic study was conducted to confirm efficacy in terms of hormone suppression and safety of the 3-month depot formulation. Thereafter, a parallel-group, open-labelled, randomized trial was performed to compare clinical efficacy and safety profiles of the 1- and 3-month depot formulations. Patients with a histologically and/or cytologically confirmed advanced prostate carcinoma, without prior hormonal or surgical androgen deprivation, are included. According to 1:2 randomization, patients are treated with either the 1- or 3-month depot for 9 months. To prevent initial flare-up, a concomitant antiandrogen therapy might be administered within 2 weeks prior to first injection and continued for up to 3 weeks. The clinical efficacy of the formulations is assessed by both objective response, EORTC and NPCTG response criteria, and subjective response by using WHO performance status. In addition, the level of prostate-specific antigen is determined every 3 months. The efficacy of the two formulations is also evaluated by determination of serum testosterone, dihydrotestosterone, luteinizing hormone and follicle stimulating hormone. To date, 106 patients have been treated with the 3-month depot and 53 patients with the 1-month depot. Preliminary evaluation shows a satisfying level of testosterone suppression with both the 3- and 1-month depot formulations. Therapeutic equivalence was assumed. The 3-month depot is tolerated as well as the 1-month depot.