Myovant Sciences Announces Positive Study Results for Possible New Endometriosis Drug

Endometriosis can be very painful and have a significant impact on everyday life and daily functioning. There is no cure, but there are treatments available. A new medication being studied recently showed promise in treating endometriosis.

The SPIRIT1 study is the second of two Phase 3 studies looking at once-daily relugolix combination therapy (relugolix, estradiol, and norethindrone acetate) in women with endometriosis pain.¹ Newly-released results of the study show positive results for the treatment. Not only did it meet the main efficacy goals (endpoints), it also met all 7 secondary goals as well.^1,2 The drug is already approved in Japan. It is now being studied in the U.S. for endometriosis, and was approved to treat advanced prostate cancer in December 2020.

What is relugolix?

Relugolix is an oral gonadotropin-releasing hormone (GnRH) receptor antagonist. It is taken once-daily and works by lowering the production of ovarian estradiol.² The ovarian estradiol can encourage uterine fibroid growth and endometriosis, and in men, testicular testosterone.² In the study, the drug is made of 40mg of relugolix, 1.0mg estradiol, and 0.5mg norethindrone acetate.²

What did the study show?

Results showed meaningful reductions in pain for 74.5 percent of women with menstrual pain and 58.5 percent of women with non-menstrual pelvic pain (compared to the placebo group which had reductions of 26.9 percent and 39.6 percent, respectively). The combination drug also resulted in a 73.3 percent decrease in the severity of menstrual cramp pain.²

This is consistent with an earlier SPIRIT2 study, which also showed benefits of the combination drug.

The study met secondary goals as well, including:²

• Changes in average menstrual cramp pain and overall pelvic pain
• Reduced impact of pain on daily activities
• Less use of pain medicines
• Changes in the average non-menstrual pelvic pain
• Fewer women using opioids
• Less painful intercourse

The drug was generally well-tolerated, with minimal bone density loss. Few of the study participants reported adverse effects The only effects being reported by at least 10 percent of women were headache and hot flashes.³

What does this mean?

The drug will now be studied more deeply. Participants from the SPIRIT1 and SPIRIT2 studies will be invited to get combination relugolix therapy for an additional 80-week period.³ This will help doctors gather data on long-term results and side effects. This data will be used to see if the drug is safe enough to be sold to the U.S. public.^2,3

Although there is no cure for endometriosis, this study shows promise for a new treatment to treat painful symptoms. It may also mean an alternative to more invasive treatments like surgery. More information is still needed, but this looks hopeful for endometriosis treatment.