Many men with advanced prostate cancer who are on hormone therapy (ADT) use one of the newer drugs, degarelix (Firmagon) to achieve a state of castration. Degarelix is considered a superior drug for initiating ADT because it is not accompanied with a PSA flare that is common with the older luteinizing hormone-releasing hormone (LHRH) agonists and LHRH antagonists.
Degarelix is more expensive than these other drugs and it is very common for men to be switched from degarelix to one of the other dugs. But, what happens when a man is switched? Given the large number of men who are switched knowing this is vital.
To evaluate for a possible testosterone surge during transition of therapy from degarelix to leuprolide (Lupron) researcher conducted a prospective, single-arm, open-label trial. In the study men were administered 3 monthly depot injections of degarelix, followed by one 3-month depot injection of leuprolide. The researchers considered a rise in serum testosterone to be clinically relevant in previously castrate men whose testosterone rose above 50 ng/dL.
They had Forty-five men aged 59-86 years included in the final analysis after completing the entire 6-month study.
They found that fluctuations in serum testosterone after the transition of therapy agents were mild and short-lived with 8.9% of men experiencing testosterone elevations to non-castrate levels.
Although the study authors described this as a mild and short-lived effect and that it included just 8.9% of the subject men we at Malecare have some concerns. First, the researchers used the measure of castration of 50 ng/dL, we believe that at the clinical level a better measure is 20 ng/dL. Without seeing the raw data we cannot say if this more stringent measure was used how many more men would have been determined to become non-castrate. We also feel that there should be a clinical recommendation that Casodex be given prior to the transition to protect the 8.9% of the known men who will experience a flare as well as those unknown numbers whose testosterone levels might fall between 20 ng/dL and 0 ng/dL.
Zuckerman JM, Eure G, Malcolm J, Currie L, Given R Urology. 2014 Mar;83(3):670-4.
Joel T. Nowak, M.A., M.S.W.