Positive results were announced from the LIBERTY randomized withdrawal study evaluating relugolix combination therapy in women with uterine fibroids.

The double-blind, placebo-controlled phase 3 study included 229 women who completed the LIBERTY long-term extension study (ClinicalTrials.gov: NCT03412890) and met the responder criteria (defined as a menstrual blood loss volume of less than 80mL and a 50% or greater reduction from baseline in menstrual blood loss volume during the last 35 days of treatment measured using the alkaline hematin method) at 1 year.

At week 52, patients were randomly assigned to receive once-daily relugolix combination therapy (relugolix 40mg plus estradiol 1.0mg and norethindrone acetate 0.5mg) or placebo for 1 year; those on placebo who had heavy menstrual bleeding during the study were offered retreatment with open-label relugolix combination therapy.

Results showed that 78.4% of patients who continued on the combination therapy remained responders (menstrual blood loss <80mL) through week 76 vs 15.1% of patients who discontinued treatment at week 52 (<.0001). Moreover, 69.8% of patients who continued treatment remained responders through week 104, while 88.3% of those who discontinued treatment relapsed with heavy menstrual bleeding (median time of return to heavy menstrual bleeding: 5.9 weeks).

Nasopharyngitis was reported to be the most common adverse event in patients treated with relugolix combination therapy. In the subset of patients who continuously received treatment (n=31), bone mineral density was found to be maintained through 2 years.

“We believe that these study results offer encouraging data in support of longer-term efficacy in women suffering from uterine fibroids,” said James Rusnak, MD, PhD, Senior Vice President, Chief Development Officer, Internal Medicine and Hospital, Global Product Development at Pfizer.

Relugolix is an investigational oral gonadotropin-releasing hormone antagonist. The Food and Drug Administration (FDA) is currently reviewing the New Drug Application (NDA) for relugolix combination tablet (relugolix, estradiol, norethindrone acetate) for the treatment of women with heavy menstrual bleeding associated with uterine fibroids. A decision on approval is expected on June 1, 2021.


Myovant Sciences and Pfizer announce positive data from phase 3 LIBERTY randomized withdrawal study of once-daily relugolix combination therapy in women with uterine fibroids. [press release]. Basel, Switzerland and New York, NY: Myovant Sciences and Pfizer Inc; March 24, 2021.