Today, the U.S. Food and Drug Administration (FDA) approved relugolix (Orgovyx) for the treatment of adult patients with advanced prostate cancer.
“Today’s approval marks the first oral drug in this class and it may eliminate some patients’ need to visit the clinic for treatments that require administration by a health-care provider,” said Richard Pazdur, MD, Director of the FDA’s Oncology Center of Excellence and Acting Director of the Office of Oncologic Diseases in the FDA’s Center for Drug Evaluation and Research. “This potential to reduce clinic visits can be especially beneficial in helping patients with cancer stay home and avoid exposure during the coronavirus pandemic.”
The American Cancer Society estimates that in 2020, there will have been more than 190,000 cases of prostate cancer in the United States. One of the treatment options for advanced prostate cancer is androgen-deprivation therapy, which uses drugs to lower levels of the hormones that help prostate cancer cells grow. Current FDA-approved treatments of this type are injected or placed as small implants under the skin. Relugolix is an orally administered gonadotropin-releasing hormone receptor antagonist that works by blocking the pituitary gland from producing luteinizing hormone and follicle-stimulating hormone, thereby reducing the amount of testosterone the testicles are able to make.
Clinical Trial
The safety and efficacy of relugolix was evaluated in the randomized, open-label, phase III HERO trial in men with advanced prostate cancer. The patients randomly received either relugolix once daily or injections of leuprolide, another hormone-targeting drug, every 3 months for 48 weeks. The objective was to determine if relugolix achieved and maintained low enough levels of testosterone (castrate levels), by day 29 through the end of the treatment course. The castration rate was 96.7% in the patients who received relugolix (n = 622) vs 88.8% in those who received leuprolide (n = 308).
Adverse Events
The most common side effects of relugolix include hot flush, increased glucose, increased triglycerides, musculoskeletal pain, decreased hemoglobin, fatigue, constipation, diarrhea, and increased levels of certain liver enzymes. Concurrent use of relugolix with drugs that inhibit P-glycoprotein, which plays a role in pumping toxins out of cells, is contraindicated. 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.
Based on findings in animals and the mechanism of action, relugolix can cause fetal harm and loss of pregnancy when administered to pregnant women; it is advised that men with female partners of reproductive potential use effective contraception during treatment and 2 two weeks after the last dose of relugolix. Due to the drug’s suppression of the pituitary gonadal system, diagnostic test results of the pituitary gonadotropic and gonadal functions conducted during and after taking relugolix may be affected.
