A leading cancer surgeon has described Ferring's new prostate cancer drug degarelix, as a "breakthrough" on the basis of fresh Phase III results.

The annual European Association of Urology Congress in Milan heard how the medicine lowered levels of testosterone in prostate cancer patient almost as effectively as surgical castration, the treatment of last resort. The drug, an injectable gonadotropin-releasing hormone antagonist, was also shown to drive down levels of the male hormone immediately – unlike currently available treatments.

"Our goal is always to have a fast and sustained reduction in testosterone levels" said John Anderson, a consultant urological surgeon at the Royal Hallamshire Hospital in Sheffield, UK. "This new data shows that degarelix produced an extremely rapid impact, approaching the immediacy of surgery."

The Phase III study compared the effect of monthly degarelix with that of standard chemical castration (7.5mg monthly doses of the LHRH agonist leuprorelin) in a 12-month randomised, open-label, parallel-group study. Each treatment group contained patients with an equivalent spread of disease progression and degarelix suppressed serum testosterone and prostate specific antigen significantly faster than leuprorelin. In addition, degarelix was able to sustain these low levels during the entire 12-month study.

By day three of the study, testosterone levels were suppressed to less than or equal to 0.5ng/mL in 96.1% of patients in the degarelix arms of the study compared to 0% in the leuprorelin arm. By day 14, 100% of patients in the degarelix arms achieved suppression of testosterone levels at less than or equal to 0.5ng/mL compared to 18.2% in the leuprorelin arm.

Mr Anderson, who is also the medical adviser to the UK Prostate Cancer Charity, said the results showed degarelix's ability to cut testosterone levels almost immediately – in contrast with the tendency of standard anti-testosterone therapy to increase levels of the male hormone in the first days or weeks of treatment.

Other recent studies have suggested that patients whose testosterone levels initially soared at the beginning of chemical castration therapy tended to have worse outcomes. "I'm certain that this drug will allow me to manage patents with prostate cancer better," Mr Anderson said. "This is a breakthrough in the treatment of the disease."

Clinical endpoint data on degarelix are not yet available. Mr Anderson believed, however, that given the superior results on immediate testosterone lowering and PSA levels, the new drug would increase survival in patients. The study showed that the drug was at least as well tolerated at current standard therapy. Significantly, the drug was not been seen to cause dangerous systemic reactions of the type that have dogged the earlier GnRH blocker drug, abarelix, made by Plenaxis.

Dr Erik Briers, of patient organisation Europa Uomo in Belgium, noted that "a pharmaceutical treatment that could offer extremely rapid suppression of testosterone would be a very welcome addition to the options for men with prostate cancer."

Prostate cancer is the most common form of cancer in men, and the second leading cause of cancer death. In the US 218,890 new cases were estimated for 2007, with a mortality rate of 27,050. In 2005, 127,490 new cases were diagnosed in the five biggest European countries and 18,310 in Japan.

Ferring submitted a New Drug Application to the FDA and EMEA in February this year for degarelix to treat
advanced and early stage prostate cancer.