Pfizer, Myovant begin dosing in relugolix contraceptive study

Pfizer and Myovant have announced that dosing has begun in a Phase III study evaluating the contraceptive efficacy of their relugolix combination tablet.

The relugolix combination tablet (relugolix 40 mg, estradiol 1.0 mg, and norethindrone acetate 0.5 mg) will be evaluated in healthy women aged 18-35 years who are at risk for pregnancy.

The primary efficacy endpoint of the SERENE study is the at-risk Pearl Index, defined as the number of on-treatment pregnancies per 100 women-years of treatment.

On-treatment pregnancies are defined as pregancies with an estimated contraception date between the first day of study intervention intake up to and including seven days after the last intake of study medication.

Women involved in the study will take once-daily relugolix combination tablet for 13 28-day at-risk cycles, Pfizer and Myovant said in a statement.

In March, Pfizer and Myovant announced that the relugolix combination therapy could have ‘potential benefit’ for the long-term treatment of women with uterine fibroids.

The LIBERTY randomised withdrawal study enrolled women who had previously competed the LIBERTY long-term extension study.

Women with uterine fibroids were randomised at week 52 to receive once-weekly relugolix combination therapy or placebo for a one-year treatment period.

The study met its primary endpoint, with 78.4% of women who continued on relugolix combination therapy achieving the sustained responder rate (menstrual blood loss < 80 mL) compared with 15.1% of women who discontinued treatment through week 76.

"We are committed to redefining care for women, which means supporting their overall health and quality of life,” said Juan Camilo Arjona Ferreira, chief medical officer of Myovant Sciences.

"Many women with uterine fibroids and endometriosis need to simultaneously manage their symptoms and their reproductive choices – including prevention of pregnancy,” he added.