Relugolix safely alleviates menstrual and non-menstrual pelvic pain in women with endometriosis when administered once-a-day in combination with estradiol and progestin, data from a Phase 3 trial show.
“The clinically-meaningful results announced today are highly encouraging, especially since the same dose that achieved significant improvement in pain also demonstrated a well-tolerated safety profile including minimal bone mineral density loss,” Linda Giudice, MD, PhD, distinguished professor in reproductive sciences at the University of California, San Francisco, said in a press release.
Developed by Myovant Sciences, relugolix is a small molecule that blocks signals from gonadotrophin-releasing hormone, reducing the production of estrogen in the ovaries. Estrogen is known to stimulate the growth of uterine fibroids — noncancerous growths that can lead to heavy menstrual bleeding, pelvic pain, and endometriosis.
By reducing the levels of estrogen in women with endometriosis, relugolix is thought to alleviate menstrual pain, as well as other symptoms of the condition. The medication is also being investigated as a form of treatment for men with advanced prostate cancer, due to its ability to lower the levels of the male hormone testosterone, which is known to stimulate the growth of cancer cells.
Two twin Phase 3 trials — SPIRIT 1 (NCT03204318) and SPIRIT 2 (NCT03204331) — have been launched to assess the safety and efficacy of relugolix at alleviating menstrual and non-menstrual pelvic pain in women with endometriosis.
During both trials, women were randomly assigned to one of three groups: the relugolix combination therapy, consisting of relugolix tablets (40 mg) plus capsules of estradiol (1.0 mg) and progestin (norethindrone acetate, 0.5 mg) once a day, for 24 weeks; relugolix alone for 12 weeks, followed by the combo therapy for another 12 weeks; or a placebo for 24 weeks.
Estradiol and progestin are artificial forms of the female hormones estrogen and progesterone. They were used in combination with relugolix to compensate for its effects at lowering the levels of estrogen in the body, and reduce the risks of unwanted therapy side effects, including bone fragility.
The two main goals of both trials were to assess the impact of the combo therapy on menstrual pain and non-menstrual pelvic pain reported by patients. Secondary goals included safety assessments, impact of the combo therapy on bone mineral density, pain during sexual intercourse, and opioid use.
New data from SPIRIT 2 now announced by Myovant revealed that the study met its primary goals of showing the superiority of the combo therapy over placebo at reducing menstrual and non-menstrual pelvic pain in women with endometriosis.
In the women receiving the combo therapy, 75.2% experienced relief in menstrual pain, compared with 30.4% in the placebo group, and 66.0% reported relief in non-menstrual pelvic pain, compared with 42.6% of those taking the placebo.
Statistics also indicated that on average, women treated with the relugolix combo therapy experienced a reduction of 75.1% in their levels of menstrual pain over the course of the study.
Additionally, the combo therapy showed superiority over the placebo in six key secondary goals assessed at week 24. These included a significant increase in the proportion of women who did not experience pain during sexual intercourse and those who did not require opioids to manage their pain.
Safety assessments revealed the combo therapy was safe and well-tolerated. The incidence of adverse events was similar in women treated with the relugolix combo therapy (80.6%) and in those given the placebo (75.0%). The most common adverse events reported were headaches, common colds, and hot flashes.
Bone mineral density assessments performed at week 24 revealed that the combo therapy led to minimal bone loss.
“Building on our successful Phase 3 studies in uterine fibroids, we are very pleased with the positive results from our first Phase 3 study in endometriosis which brings us closer to realizing our vision of a one dose, one pill, once a day potential treatment that balances clinically-meaningful symptom relief with a well-tolerated safety profile for women suffering from these diseases,” said Lynn Seely, MD, CEO of Myovant Sciences.
“We look forward to sharing the results from our replicate Phase 3 study [SPIRIT 1] in endometriosis later this quarter,” she added.
Myovant also announced that in a separate open-label Phase 1 trial, the relugolix combo therapy successfully prevented ovulation in 67 healthy women over the course of the entire treatment period (84 days). After discontinuing treatment, all women participating in the study resumed ovulation within an average period of 23.5 days.
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