The US FDA has recently approved relugolix (Orgovyx) as the first oral androgen deprivation therapy for adults with advanced prostate cancer, announced Myovant Sciences.
Relugolix is a small molecule, gonadotropin-releasing hormone (GnRH) receptor antagonist. The drug blocks the pituitary gland from making luteinizing hormone and follicle-stimulating hormone, thereby reducing the amount of testosterone made by the testicles.
The safety and efficacy of relugolix were evaluated in a randomised, open-label trial in men with advanced prostate cancer. Patients were randomly assigned to receive relugolix once daily or injections of leuprolide every three months for 48 weeks.
The objective was to determine if relugolix achieved and maintained sufficiently low levels of testosterone (castrate levels) by day 29 through the end of the treatment course. In the 622 patients who received relugolix, the castration-equivalent rate was 96.7%.
Androgen deprivation therapies such as relugolix may affect the heart’s electrical properties or cause electrolyte abnormalities; therefore, health care providers should consider periodic monitoring of electrocardiograms and electrolytes.
Because relugolix suppresses the pituitary-gonadal system, diagnostic test results of the pituitary gonadotropic and gonadal functions conducted during and after taking relugolix may be affected.
The most common side effects of relugolix include hot flush, musculoskeletal pain, fatigue, constipation and diarrhoea; increased levels of glucose, triglycerides and liver enzymes; and decreased levels of haemoglobin.