Efficacy and safety of leuprorelin acetate 6-month depot in prostate cancer patients: a Phase III, randomized, open-label, parallel-group, comparative study in Japan.

Leuprorelin acetate (TAP-144-SR) is commonly used worldwide in prostate cancer patients. This study was conducted to assess the non-inferiority of a 6-month depot formulation of TAP-144-SR (TAP-144-SR [6M]) 22.

5 mg to a 3-month depot formulation of TAP-144-SR (TAP-144-SR [3M]) 11. 25 mg in prostate cancer patients in Japan.

This was a 48-week Phase III, open-label, parallel-group comparative study. TAP-144-SR (6M) 22. 5 mg (6M group) and TAP-144-SR (3M) 11. 25 mg (3M group) were administered to 81 and 79 subjects, respectively. The primary endpoint was the rate of serum testosterone suppression to the castrate level (≤100 ng/dl).

Serum testosterone of all subjects excluding one subject in the 3M group was suppressed to the castrate level throughout 48 weeks. The estimated between-group difference (6M group - 3M group) in suppression rate was 1. 3% (95% confidence interval: -3. 4, 6. 8), and its lower confidence interval was more than -10% of the pre-determined allowable limit value to judge the non-inferiority. The prostate-specific antigen concentrations were stable throughout the study in both groups. Progressive disease in the best overall response based on the Response Evaluation Criteria In Solid Tumors was 0. 0% for the 6M group and 2. 6% for the 3M group. Adverse events occurred in 92. 6% in the 6M group and 89. 9% in the 3M group. Adverse events leading to discontinuation were reported in 2. 5% in the 6M group and 3. 8% in the 3M group.

TAP-144-SR (6M) was not inferior to TAP-144-SR (3M) for the suppressive effect on serum testosterone level. TAP-144-SR (6M) was also as well tolerated as TAP-144-SR (3M).

Japanese journal of clinical oncology. 2015 Oct 20 [Epub ahead of print]

Kazuhiro Suzuki, Mikio Namiki, Tsukasa Fujimoto, Nobuyoshi Takabayashi, Kentarou Kudou, Hideyuki Akaza

Department of Urology, Gunma University Graduate School of Medicine, Gunma, Department of Integrative Cancer Therapy and Urology, Kanazawa University Graduate School of Medical Science, Ishikawa. , Takeda Pharmaceutical Company Limited, Osaka. , Takeda Pharmaceutical Company Limited, Osaka. , Takeda Pharmaceutical Company Limited, Osaka. , Department of Strategic Investigation on Comprehensive Cancer Network, The University of Tokyo, Tokyo, Japan.