How it Works
Relugolix is an oral, once-daily, gonadotropin-releasing hormone (GnRH) receptor antagonist. Inhibition of GnRH receptors in the anterior pituitary by relugolix prevents secretion of GnRH, which thereby reduces the circulating gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH), leading to the suppression of estrogen production in women and testosterone production in men. Myovant’s ongoing clinical trials are investigating whether relugolix can adequately and consistently suppress these hormones and improve the symptoms of uterine fibroids and endometriosis in women and decrease prostate-specific antigen (PSA) levels in men with advanced prostate cancer.
Relugolix Clinical Study Results for the Treatment of Uterine Fibroids
In a double-blind, placebo-controlled Phase 2 clinical trial in 216 patients with uterine fibroids, women who received relugolix experienced a statistically significant reduction in heavy menstrual bleeding and relugolix was generally well-tolerated.
In a double-blind non-inferiority Phase 3 study conducted by Takeda in Japan to evaluate the efficacy and safety of relugolix in 280 women with heavy menstrual bleeding associated with uterine fibroids, relugolix met the study’s primary endpoint with the proportion of patients achieving a pre-defined reduction in menstrual bleeding similar to that achieved by the approved product leuprorelin (also known as leuprolide acetate). The frequency of adverse events was similar between treatment groups and there were no unexpected adverse events reported.
In a randomized, double-blind placebo-controlled Phase 3 study conducted by Takeda in Japan to evaluate the efficacy and safety of relugolix in 65 women for the treatment of pain symptoms associated with uterine fibroids compared to placebo, relugolix met the primary endpoints with 57.6% of women treated with relugolix demonstrating improvement in pain symptoms vs. 3.1% of women receiving placebo and adverse events were consistent with the mechanism of action of relugolix.
Relugolix Clinical Study Results for the Treatment of Endometriosis
In a double-blind, placebo-controlled Phase 2 trial in 487 patients with endometriosis, women who received relugolix experienced statistically significant reductions in non-menstrual and menstrual pelvic pain and the frequency of adverse events were consistent with prior studies.
Relugolix Clinical Study Results for the Treatment of Advanced Prostate Cancer
In two randomized Phase 2 studies in approximately 228 men with advanced prostate cancer, oral once-daily relugolix suppressed serum testosterone to castrate levels and decreased PSA.
Unlike GnRH agonists, relugolix does not cause transient increases in gonadotropin secretion (flare), which can result in an initial worsening of clinical symptoms. Upon treatment discontinuation, hormone levels return to baseline within days in some cases.