On Friday, December 18, 2020, the US FDA approved the first oral gonadotropin-releasing hormone (GnRH) receptor antagonist, relugolix, for adult patients with advanced prostate cancer. This is an important advance because it offers another option to patients who are taking hormone therapy.
One of the mainstays of treatment for high-risk and metastatic prostate cancer is androgen deprivation therapy (ADT). ADT is designed to stop testosterone from being produced or directly block it from acting on prostate cancer cells, slowing or stopping cancer growth. Most forms of ADT are given as regular injections (e.g., monthly or every 3 months) or as implants under the skin. One disadvantage of commonly use medications is an initial spike in testosterone, as well as a delay in time to lowering the man’s testosterone level.
This newly-approved therapy, relugolix, works by blocking the pituitary gland (in the brain) from making hormones that stimulate the testes to make testosterone – thereby lowering a man’s testosterone levels. Instead of an injection, the patient takes an oral tablet once daily, at approximately the same time each day, with or without food.
The effects were tested in a randomized clinical trial comparing relugolix to leuprolide, a very common injectable form of ADT, in over 900 patients with advanced prostate cancer. More patients taking relugolix had their testosterone levels fall quickly and remain at a low (“castrate” level) during the study vs those taking leuprolide.
Side effects of ADT can include weight gain, increase in cholesterol levels, and increased risk for heart attack. A striking finding in the clinical trial was a 54% decrease in major cardiac events (such as heart attack and stroke) in the patients taking relugolix vs leuprolide.
What does this approval mean for patients with advanced prostate cancer? They now have an oral alternative to typical ADT that decreases testosterone levels more quickly, and keeps them low, than one commonly used medication. Some patients and doctors may decide that taking an oral medication at home, rather than having to come to the clinic for an injection, may be preferable during the COVID-19 pandemic. Many men with prostate cancer already have risk factors for cardiovascular disease, and relugolix may offer reduced risk of dangerous side effects such as a heart attack. This may be an important consideration when choosing a form of ADT.
We at PCF are thrilled when patients and doctors have another choice of therapy in the fight against prostate cancer. PCF congratulates all of the scientists and clinicians who helped to make this breakthrough possible.