Effectiveness, pharmacokinetics, and safety of triptorelin acetate microspheres in patients with locally advanced and metastatic prostate cancer.

Background: A newly generic microspheres, sustained-release formulation of triptorelin acetate 3.75 mg has been developed.

Objectives: To evaluate the efficacy, pharmacokinetics, and safety of triptorelin 1-month formulation in Chinese patients with prostate cancer.

Design: An open-label, multicenter clinical trial with one arm testing a 1-month sustained-release triptorelin formulation in prostate cancer patients.

Methods: Patients with prostate cancer received three consecutive 28-day injections of triptorelin acetate. The primary endpoint was the proportion of successful patients over the total number of evaluable patients. Treatment success was defined as testosterone suppression below the clinical castration level (i.e., <0.5 ng/mL) at day 28 and maintenance of clinical castration until study completion (day 84). The frequency of patients with testosterone concentrations <0.2 ng/mL was also studied.

Results: The study included 125 patients. All 125 patients received at least one dose of the study drug and 122 completed the study. The successful patient proportion among the evaluable patients was 97.6% (122/125; 95% CI, 92.7-99.2). 95.1% (116/122) achieved testosterone concentrations <0.2 ng/mL. The pharmacokinetic profile of triptorelin during the first 3 months of treatment, evaluated in a subset of the study population (n = 11), showed sustained release of triptorelin from the formulation. Values for AUC_0-τ calculated from day 0 to 28, and day 56 to 84 were 134.42 (28.76), and 154.72 (21.86) h*ng/mL, respectively. The most common treatment-related adverse events were increased alanine aminotransferase (18.4%), increased aspartate aminotransferase (16.0%), and hot flashes (9.6%). Prolonged QT interval on electrocardiogram, erectile dysfunction, and decreased libido each occurred in ⩽4% of the patients. The frequently reported local adverse reaction was pain at the injection site, experienced by 2.4% (3/125) of the patients.

Conclusion: 3.75-mg Triptorelin acetate microspheres for injection were effective in achieving and maintaining testosterone suppression and were well tolerated in patients with prostate cancer.

Trial registration: chictr.org.cn (ChiCTR2000033188).