Switching from an LHRH Antagonist to an LHRH Agonist: A Case Report of 10 Finnish Patients with Advanced Prostate Cancer

INTRODUCTION Luteinizing hormone-releasing hormone (LHRH) analogues are widely used for the treatment of advanced hormone-dependent prostate cancer. However, there are currently no clinical guidelines for switching between LHRH analogues. It has been reported that there may be clinical benefits for patients switching between different formulations of LHRH agonists, as well as from an LHRH agonist to LHRH antagonist, but there are no published data on switching from an LHRH antagonist to an LHRH agonist. In this paper, we summarize the clinical notes of 10 patients with hormone-sensitive advanced prostate cancer who switched from an LHRH antagonist to an LHRH agonist. METHODS Patients with T3N0M0-T4N1M1 prostate cancer experiencing injection site reactions, such as pain and swelling, with monthly degarelix (Firmagon®) subcutaneous injections were switched to the 3-monthly leuprorelin acetate implant (Leuprorelin Sandoz®) subcutaneous injections. RESULTS Mean patient age was 75 years (SD 8.3; range 59-85) and Gleason scores ranged from 7 to 9. The mean [±standard deviation (SD)] duration of degarelix treatment was 5 ± 3.7 months (range 2-13). After switching, prostate serum antigen levels were comparable or reduced from those measured prior to switching, showing that efficacy was not compromised. Throughout the course of treatment, no patients reported injection site reactions. Patients reported increased satisfaction with the leuprorelin acetate implant versus degarelix, mainly because of a lack of injection site reactions and reduced frequency of injection. CONCLUSION This is the first report of the clinical experience and potential cost implications of switching from an LHRH antagonist to an LHRH agonist. These data are consistent with other experiences of switching between LHRH analogues in terms of efficacy, safety, and potential cost savings, and provide preliminary evidence that the switch from an LHRH antagonist to an agonist is safe and equally efficacious.