Relugolix (also known as Relumina, TAK-385, or RVT-601) is a gonadotropin-releasing hormone (GnRH) receptor antagonist being developed and tested by Myovant Sciences. This oral once-daily medicine is intended to treat endometriosis, as well as uterine fibroids and hormone-sensitive prostate cancer.
How relugolix works
By inhibiting GnRH receptors in the anterior pituitary gland, which is the major organ of the hormonal system in the brain, relugolix rapidly reduces circulating gonadotropins. The two main gonadotropins (so-called because they stimulate the gonads — testes and ovaries) are luteinizing hormone and follicle-stimulating hormone. The inhibition of these gonadotropins leads to the suppression of the production of estrogen in women and testosterone in men.
Relugolix has been shown to improve the symptoms of endometriosis and uterine fibroids in women, and decrease prostate-specific antigen levels in men with advanced prostate cancer.
Relugolix in clinical trials
In an article published in the European Journal of Pharmacology in 2014, researchers reported that relugolix may prove to be a useful therapy for hormone-dependent diseases such as endometriosis, uterine fibroids, and prostate cancer.
In a double-blind, placebo-controlled Phase 2 clinical trial (NCT01458301) in 487 patients with endometriosis, women who received relugolix experienced statistically significant reductions in non-menstrual and menstrual pelvic pain. The multicenter study evaluated the safety of relugolix at three doses (10 mg, 20 mg, and 40 mg) administered orally once daily for 12 weeks. Efficacy was exploratory and assessed using leuprorelin as a comparator. The primary endpoint was the reduction of pelvic pain as measured by the visual analog scale.
An extension study (NCT01452685) looked at the long-term safety and efficacy of relugolix, again at three doses (10 mg, 20 mg, and 40 mg) administered by mouth each day for 24 weeks in 397 women with endometriosis-associated pain who had participated in the preceding 12-week study. The primary endpoint of the extension study was safety, including an assessment of change in bone mineral density using dual-energy X-ray absorptiometry. Results showed that treatment with relugolix for 24 weeks was generally well-tolerated, and it reduced pelvic pain and demonstrated benefits similar to leuprorelin.
In 2017, the 12-week findings from the Phase 2 trial were presented at the 13th World Congress on Endometriosis while the 24-week data from the extension study were presented at the 19th European Congress of Endocrinology.
Relugolix was also evaluated in a double-blind, placebo-controlled Phase 2 clinical trial (NCT01452659) in 216 women with uterine fibroids, with results showing that the treatment led to a reduction in menorrhagia, or heavy menstrual bleeding.
Myovant has moved into testing relugolix in two Phase 3 trials for women with endometriosis-associated pain. Two trials, called SPIRIT1 (NCT03204318) and SPIRIT2 (NCT03204331), are each currently recruiting an estimated 600 women worldwide, who will be divided into three groups. Those in the first group will receive relugolix plus add-back therapy for 24 weeks. The second group will receive relugolix by itself for 12 weeks and then another 12 weeks in combination with add-back therapy. The third group will receive a placebo for 24 weeks. Add-back therapy usually involves estrogen and/or progesterone to help reduce or reverse osteoporosis caused by GnRH antagonists.
After 24 weeks, the patients will be invited to participate in an open-label extension of the trial, called SPIRIT EXTENSION (NCT03654274), for up to 80 weeks. The trial is expected to enroll 800 participants.
Last updated: August 1, 2019
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