Degarelix binds to the GnRH receptors in the anterior pituitary gland, which reduces the release of luteinising hormone (LH) and follicle stimulating hormone (FSH) leading to a reduction in the secretion of testosterone by the testes. Cancerous prostate tumours are androgen-sensitive and respond to the removal of androgens.
Degarelix does not produce a surge in testosterone or potential symptomatic flare, eliminating the need to co-prescribe an anti-androgen.
A three-armed, phase III trial looked at the safety and efficacy of two doses in 610 patients over 12 months.1 The three arms included a starting dose of 240mg given by subcutaneous injection (as two 3mL injections) and then maintenance doses of 80mg, 160mg or monthly intramuscular injections of leuprorelin 7.5mg.
Degarelix was non-inferior to leuprorelin at maintaining low testosterone levels over the 12-month treatment period. The primary endpoint of the trial was the suppression of testosterone to ≤0.5ng/ml at all monthly measurements from day 28. The endpoint was achieved by 97.2, 98.3 and 96.4 per cent of patients in the degarelix 240/80mg, degarelix 240/160mg and leuprorelin groups, respectively. The median PSA levels at days 14 and 28 were significantly lower for the degarelix groups than the leuprorelin group. Treatment with degarelix resulted in rapid suppression of testosterone levels and by day three the median testosterone levels were <0.5ng/ml in 96.1, and 95.5 per cent in the degarelix 240/80mg and 240/160mg groups respectively. The median testosterone level for patients in the leuprorelin group increased by 65 per cent from baseline by day three.
- Klotz L, Boccon-Gibod L, Shore N et al. The efficacy and safety of degarelix: a 12-month, comparative, randomised, open-label, parallel -group phase III study in patients with prostate cancer. BJU International 2008; 102: 1531-38
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