On December 24, 2008, the U. S. Food and Drug Administration (FDA) approved degarelix for injection (Ferring Pharmaceuticals Inc., Parsippany, NJ), a new gonadotropin releasing hormone (GnRH) receptor antagonist, for the treatment of patients with advanced prostate cancer. This indication is based on degarelix’s effectiveness in attaining and maintaining serum testosterone suppression to medical castration levels during 12 months of treatment in an open-label, randomized, multi-center, parallel-group study.
A total of 620 patients were randomized to receive one of two degarelix dosing regimens or leuprolide for one year: degarelix at a starting dose of 240 mg followed by monthly doses of 160 mg subcutaneously, degarelix at a starting dose of 240 mg followed by monthly doses of 80 mg subcutaneously, or monthly doses of leuprolide 7.5 mg intramuscularly. The primary objective was to demonstrate that degarelix is effective in achieving and maintaining testosterone suppression to castration levels ( ≤ 50 ng/dL) during 12 months of treatment. The medical castration rates were 98.3% (95% CI: 94.8%; 99.4%) in the degarelix 240/160 mg arm, 97.2% (95% CI: 93.5%; 98.8%) in degarelix 240/80 mg arm, and 96.4% (95% CI: 92.5%; 98.2%) in the leuprolide 7.5 mg arm. The key secondary analyses showed that no testosterone surges were observed in the degarelix arms and that 96% of patients attained medical castration 3 days after the first degarelix dose compared to no patients receiving leuprolide.
The most commonly observed adverse reactions (frequency of <10%) in either degarelix arm included injection site reactions (e.g., pain, erythema, swelling or induration), hot flashes, weight increase, and increases in transaminases and gamma-glutamyltransferase. The majority of the adverse reactions were grade 1/2 in severity; grade 3/4 adverse reactions were uncommon. The injection site reactions were transient, with frequencies of 35-44% in the degarelix arms compared to a frequency of <1% in the leuprolide arm. Hepatic laboratory abnormalities were generally reversible, with grade 3 abnormalities in less than 1% of patients. There were no important differences in adverse reactions between the two degarelix arms, except for fewer injection site reactions in the 240/80 mg arm.
The recommended dosing regimen is a starting dose of 240 mg given as two subcutaneous injections of 120 mg each followed by monthly maintenance doses of 80 mg given as a single subcutaneous injection.
Full prescribing information, including clinical trial information, safety, dosing, drug-drug interactions and contraindications is available at Drugs@FDA
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Date created: December 29, 2008