A switch from GnRH agonist to GnRH antagonist in castration-resistant prostate cancer patients leads to a low response rate on PSA

作者：Masson Lecomte Alexandra; Guy Laurent; Pedron Philippe; Bruyere Franck; Roupret Morgan; Nsabimbona Bonaventure; Dahan Mickael; Hoffman Patrice; Salomon Laurent; Vordos Dimitri; Hoznek Andras; Le Corvoisier Philippe; Morel Pierrick; Abbou Claude; de la Taille Alexandre^*

来源：World Journal of Urology, 2013, 31(2): 339-343.

DOI：10.1007/s00345-012-0841-1

• Castration-resistant prostate cancer
• GnRH antagonist
• PSA
• Testosterone

At the time of castration resistance, it is recommended to realize hormonal manipulations before chemotherapy. We evaluated the impact of a switch from GnRH agonist to antagonist in patients with castration-resistant prostate cancer on PSA and testosterone levels at 3 months.
Retrospectively, 17 patients from 5 different centers undergoing androgen deprivation therapy and presenting rising PSA confirmed on 3 blood samples 2 weeks apart and despite a castrate testosterone level (< 0.5 ng/ml) were reviewed. Antiandrogen withdrawal syndrome had been tested before the switch. Degarelix was administered as followed: 240 mg for the first injection and then 80 mg every month, subcutaneously. We evaluated the PSA and testosterone level variation 3 months after the switch. Patients who experienced a variation in PSA of less than 10% compared to the baseline or who had a more than 10% PSA decrease were defined as responders.
Mean PSA level at the switch was 34.3 +/- A 50.3 ng/ml, with a mean testosterone level of 0.21 +/- A 0.13 ng/ml. Three months after the switch, mean PSA level was 59.9 +/- A 81.6 ng/ml (P = 0.061), with a mean testosterone level of 0.19 +/- A 0.08 ng/ml (P = 0.086). At 3 months, 4 patients (23%) responded to therapy. Thirteen patients (77%) experienced a rise in PSA of more than 10% compared to baseline; 41% of patients decreased their testosterone level. The limitations of this study are its retrospective nature and the limited number of patients.
Switch from an agonist to an antagonist of GnRH has a limited impact on PSA at 3 months in castration-resistant prostate cancer patients.

• 出版日期2013-4