[A new LH-RH agonist for treatment of prostate cancer, 3-month controlled-release formulation of goserelin acetate (Zoladex LA 10.8 mg depot)--outline of pre-clinical and clinical studies]

Abstract

Goserelin acetate is a LH-RH agonist developed by AstraZeneca (formerly ICI, UK), and has been used clinically for the treatment of prostate cancer as a 4-week controlled-release formulation (Zoladex 3.6 mg depot). Recently, a new drug (Zoladex LA 10.8 mg depot) with 3-month controlled-release formulation was developed and became commercially available in Japan. In the randomized comparative phase III studies carried out with global bases, single administration of the new drug yielded almost equivalent anti-testosterone effect and the same serum level of the previous 3.6 mg depot formulation in 3-times continuous administration. In these studies, adverse drug reactions, which were mainly due to pharmacological effects of the new drug and minimal, were found in 52.6% (41/78) compared with 54.8% (46/84) with the previous 3.6 mg depot formulation. In the phase III studies, there were no significant differences in average serum testosterone levels between the two formulations at 12 and 13 weeks after administration. In the Japanese late phase II study with untreated patients, castration effect was observed in all 20 cases entered in the trial. In 20 cases in which treatment was switched from 3.6 mg depot to the new formulation, there were no significant changes in serum testosterone levels at castration level of the untreated patients, 90% (18/20) responded to the treatment, and normalization of PSA level was found in 75.0% (15/20). The adverse drug reactions were mainly increased triglyceride level and hot flushes. In the retrospective evaluation of untreated patients in this trial and the post-marketing clinical trial data for 3.6 mg depot, it was concluded that the new drug had almost the same efficacy and safety profile as 3.6 mg depot in Japanese people. These results indicate that Zoladex LA 10.8 mg depot has the same efficacy and safety as 3.6 mg depot with administration every three months, the burden of injection of LH-RH agonist can be reduced. This new medication can be considered a new standard for treatment of prostate cancer.