In patients with non-localised
prostate cancer, medical
castration is generally achieved with a
GnRH agonist such as
triptorelin. A peripheral
antiandrogen can be added during the first weeks of treatment to counteract the initial
testosterone surge.
Degarelix is the first
GnRH antagonist to be authorised in this setting in the European Union. A randomised unblinded trial compared subcutaneous
degarelix versus intramuscular
leuprorelin, without the addition of a peripheral
antiandrogen.
Castration was achieved in almost all patients after the first month of treatment.
Testosterone levels decreased within a few days with
degarelix and more slowly with
leuprorelin, after an initial surge, and these levels were maintained in both groups throughout the one-year study period. The more rapid fall in
testosterone obtained with
degarelix, without an initial surge, did not translate into lower mortality (there were only 2
cancer deaths) or fewer adverse effects during the first month of treatment. The main adverse effects in this trial were linked to
castration: hot flushes and
weight gain. Reactions at the injection site (
pain,
erythema) were far more frequent with
degarelix than with
leuprorelin, affecting respectively about 40% and fewer than 1% of patients. The large volume of the
degarelix subcutaneous
solution (3 to 4 mi) is not very practical to administer. In practice,
degarelix has no tangible advantages over a
GnRH agonist such as
triptorelin. It is better to continue to use
triptorelin, possibly with addition of an
antiandrogen at the beginning of treatment.