Pfizer and Myovant Sciences have reported positive data from the Phase III LIBERTY withdrawal study of relugolix combination therapy in women with uterine fibroids.
Myovant’s lead product candidate, the relugolix combination tablet has relugolix 40mg in combination with estradiol 1mg and norethindrone acetate 0.5mg. It is currently reviewed by regulatory authorities in Europe and the US for women with uterine fibroids and is under development for women with endometriosis.
The double-blind, placebo-controlled study enrolled women who completed the LIBERTY long-term extension study.
They were randomised at week 52 to receive once-daily relugolix combination therapy or placebo for a double-blind treatment duration of one year. During the study, women on placebo with relapse of heavy menstrual bleeding were given re-treatment with open-label relugolix combination therapy.
This trial, along with LIBERTY 1, LIBERTY 2, and LIBERTY long-term extension studies, was intended to analyse the safety and efficacy of treatment with relugolix combination therapy for up to two years.
Data showed that 78.4% of women who received relugolix combination therapy achieved sustained responder rate (menstrual blood loss < 80mL) until week 76 versus 15.1% who discontinued treatment and initiated placebo at week 52, thereby meeting the study’s primary endpoint.
Key secondary endpoints in the study, including sustained responder rate at two years (week 104), time to relapse of heavy menstrual bleeding, and amenorrhea rate were also met.
About 69.8% of trial participants receiving relugolix combination therapy remained responders through two years, while 88.3% of participants who discontinued treatment at week 52 relapsed with heavy menstrual bleeding in 5.9 weeks.
Pfizer Global Product Development Internal Medicine and Hospital senior vice-president, chief development officer James Rusnak said: “Uterine fibroids can affect many women during their lifetime with uncomfortable symptoms, such as heavy menstrual bleeding.
“We believe that these study results offer encouraging data in support of longer-term efficacy in women suffering from uterine fibroids.”
In December 2020, Myovant Sciences and Pfizer announced a collaboration to develop and commercialise relugolix for oncology and women’s health in the US and Canada.
As per the collaboration agreement, Pfizer also received an exclusive option to commercialise relugolix in oncology outside the US and Canada, excluding some Asian countries.