Degarelix: A gonadotropin-releasing hormone receptor (GnRH) blocker, tested in two one-year multicenter, randomized, dose-finding studies in prostate cancer patients.

14516 Background: The GnRH receptor blocker degarelix has immediate onset of action in suppressing gonadotropins (LH and FSH), testosterone (T) and prostate specific antigen (PSA) and does not cause T surge. Its long-term efficacy and safety in different maintenance dosing regimens were evaluated in prostate cancer (CaP) patients. METHODS Degarelix was investigated in two multicenter, one-year studies in North America and Europe/South Africa. Degarelix initiation doses of 200 and 240 mg administered subcutaneously, followed by three maintenance doses (80, 120 and 160 mg). Therapeutic effect was assessed by measuring T and PSA levels. 314 patients (age 47-93, median 73 years) with histologically confirmed CaP, PSA ≥2 ng/mL received degarelix subcutaneously every 28 days. Median baseline T was 4.1 ng/mL and PSA was 20 ng/mL. 19% of patients had metastatic, 24% had locally advanced and 30% had localized CaP. 27% were M0/MX and not T-staged. Tumour grade was well differentiated (Gleason 2-4) in 13%, moderately differentiated (5-6) in 38%, and poorly differentiated (7-10) in 49% of the patients. RESULTS T levels ≤0.5 ng/mL were achieved in 92% of patients at Day 3 and 95% of patients at Day 28 among those treated with 240 mg (40 mg/mL) degarelix. From Day 28 until Day 364, 100% of patients receiving maintenance doses of 160 mg had T levels consistently ≤0.5 ng/mL. No evidence of T surge was detected. PSA decreased by 90% at 8 weeks after starting therapy, 94% at 12 weeks and 96% at 24 weeks. Twelve patients (6%) withdrew from the study due to adverse events, largely related to androgen deprivation. There were no cases of systemic allergic reactions. CONCLUSION Degarelix treatment for one year resulted in fast, profound and sustained suppression of T (≤0.5 ng/mL) and fast, profound and sustained reduction of PSA levels. Degarelix was well tolerated without evidence of T surge or systemic allergic reactions. [Table: see text] [Table: see text].