Efficacy of triptorelin in lowering serum testosterone (sT) in patients with advanced prostate cancer.

Abstract

162 Background: Medical castration using gonadotropin-releasing hormone (GnRH) agonists is the mainstay of treatment for advanced prostate cancer. Achievement and maintenance of castrate serum testosterone (sT) levels <50 ng/dL (1.735 nmol/mL) has been the goal of therapy. However, patients are able to achieve and maintain sT levels <15 ng/dL after surgical castration (Oefelein M et al. J Urology 2000; 56: 1021-4). Some authors have suggested that 20 ng/dL should be the target threshold for medical castration(Perachino M et al. BJU Int 2010; 105: 648-51) but the clinical relevance of achieving such low sT levels (<20 ng/dL) remains unknown. Methods: The efficacy and safety of sustained-release triptorelin pamoate 22.5 mg 6-month formulation was recently evaluated in a 12-month (48-week), multicentre, open-label, phase III study in 120 patients with locally advanced or metastatic prostate cancer and/or increased prostate specific antigen (PSA) after failed local therapy. Initial results based on the standard castration level of 50 ng/dL were previously presented in comparison to triptorelin 1- and 3-month formulations (Lundström E et al. Clin Drug Investig 2009; 29: 757-65). We report the proportions of patients achieving sT levels of <20 ng/dL with the triptorelin pamoate 1-, 3- and 6-month formulations. Results: With the 6-month formulation, sT levels of <20 ng/dL were achieved in >90% of patients on Day 169 (6 months after first triptorelin injection) and on Day 337 (6 months after second injection; Table). Similar sT levels were achieved with triptorelin 1- and 3-month formulations in a phase III study over 9 months (Table). Conclusions: A high proportion of patients receiving the 6-month triptorelin formulation achieve sT levels <20 ng/dL. This compares favorably to the triptorelin 1- and 3-month formulations. [Table: see text] [Table: see text]