Long-term clinical study on luteinising hormone-releasing hormone agonist depot formulation in the treatment of stage D prostatic cancer. The TAP-144-SR Study Group.

The results of long-term administration of leuprorelin acetate depot (TAP-144-SR), a sustained-release preparation of luteinising hormone-releasing hormone (LH-RH) agonist, to 40 stage D prostate cancer patients who had had no previous hormonal therapy, have been analyzed. The drug was administered by subcutaneous injection once every four weeks at a dose of 3.75 or 7.5 mg. The mean duration of treatment was 480 (141-1,266) days, and treatment continued for more than one year for 60% of the 40 patients. Objective response was evaluated in accordance with Japanese Response Criteria. The best objective response in the overall evaluation was a partial response in 68.6% of the total patient group (3.75 mg, 64.3%; 7.5 mg, 71.4%). During the administration period, 21 patients were diagnosed as having progressive disease (PD), and the mean time to onset of PD was 308 days. The earliest diagnoses of PD were made on bone metastases (17 cases) and prostatic acid phosphatase levels (12 cases). The survival rate, as determined by Kaplan-Meier's method, was 81.2% (3.75 mg, 80.5%; 7.5 mg, 81.3%) two years after starting the regimen and 66.0% (3.75 mg, 65.1%; 7.5 mg, 66.0%) after three years. There was no dose dependency between either of the two drug doses, which we adopted as functions of the objective response rate, and patients' survival. Serum levels of testosterone, LH and follicle-stimulating hormone (FSH) were monitored from the first-dose until the 148th week of administration. In all patients receiving the drug as scheduled, the testosterone level was maintained at less than 1 ng/ml, and the LH and FSH levels were maintained at levels lower than their respective upper normal limits. There were no particular adverse reactions specific to the long-term administration subsequent to the foregoing 12-week administration study. In conclusion, LH-RH analogue treatment is thought to be a long-lasting, effective, palliative measure for patients with previously-untreated, advanced, prostatic cancer.