There is a new kid on the hormonal therapy street, and his accomplishments to date are impressive!
The drug is degarelix, with the trade name yet to be determined, and the FDA approved this drug, developed by Ferring Pharmaceuticals, on December 31, 2008. Apparently it will be available very soon, once the trade name and label plus doctor and patient flier details are worked out.
I learned about its approval from the Us Too "Hot Sheet" for February 2009 that is given out at our support group meetings, and I've done some further checking on [url]www.pubmed.gov[/url] and elsewhere.
It supresses testosterone more rapidly than the drugs now available
, such as Lupron, Zoladex, Viadur, Trelstar LA and Eligard. All of the latter are in the drug class known as "LHRH agonists," meaning that they stimulate the normal receptor on the pituitary gland, a circumstance that then fools the body into thinking that it has produced adequate testosterone so that it shuts down almost all of further production. That cuts off a key fuel needed by the prostate cancer cells. In contrast, degarelix is an "LHRH antagonist" drug, meaning that it blocks the receptor for LHRH so that the body cannot signal that it needs more testosterone. Degarelix is the only LHRH antagonist now approved by the FDA, though at least two others are apparently available in other countries.
How good is it? The randomized, open label (meaning not blinded) Phase III trial was overseen by two leading experts, Dr. Laurence Klotz (Toronto, Sunnybrook) and Dr. Fritz Schroeder (Schroder with umlaut), both well known for their work with active surveillance, among other accomlishments. Key results in head-to-head comparision with Lupron showed that "At Day 3 of treatment, 96% of degarelix patients achieved a castrate testosterone level
compared with zero percent receiving leuprolide [Lupron]. By Day 14, 99% of degarelix patients achieved castrate levels of testosterone
, compared with 18% receiving leuprolide...." The trial also demonstrated that no flare occurred with degarelix
; that's good, because flare is typical with drugs in the Lupron class, and wise practice is to use an antiandrogen drug to prevent it, thereby avoiding a risk that a temporary surge in testosterone will cause irreversible trouble
Generally, it was well tolerated, though injection site reactions were much more common (40%) than for Lupron (< 1.0%). However, less than 1% of patients discontinued degarelix, and severe injection site reactions occurred in 2% or fewer patients receiving the drug.
As you might expect, side effects are similar to those of the LHRH agonist class of drugs such as Lupron and Zoladex.
At this point, I'm highly impressed, but there is one piece of key data I would like to see: how well it does against a lower threshold for assuming adequate suppression of testosterone. Many researchers, including the researchers in this trial, feel that lowering testosterone to 50 ng/dL (same as .5 ng/mL) is adequate, but the leaders I follow, who are experts in hormonal blockade and who have practices dedicated to just prostate cancer, want testosterone to be below 20. If they do not see that, then they alter tactics. The abstracts of the studies gave only the percentages of patients achieving the looser level of 50 ng/dL. I'm hoping that the complete papers will provide the added detail, or alternately that the researchers will publish the added detail later.
I also am curious whether this drug will enable patients to dispense with the two other elements of triple blockade that round out my intermittent triple blockade therapy: the andiandrogen drug (like Casodex or flutamide), and the 5-alpha reductase class of drug (finasteride (formerly Proscar) or Avodart). Those questions are not clear from what I see at this point. However, from the graphic diagram on page 134 of "A Primer on Prostate Cancer - The Empowered Patient's Guide," it appears that degarelix would also cancel the signal that triggers indirect production of testosterone by the adrenal gland, even if it does not block the androgen receptor, as Casodex (etc.) does.
But I'm getting analytical here - it's a habit, since I think my life may depend on it.
Taking a larger view, it is clear that development of degarelix is a magnificent accomplishment!