A combination therapy using the experimental drug relugolix was effective in treating pain and heavy bleeding from uterine fibroids for a full year, according to findings from a long-term extension study of the phase 3, open-label LIBERTY trials.
The drug was also well tolerated, with retention of bone mineral density and no new adverse events, said Ayman Al-Hendy, MD, PhD, who presented the results Oct. 17 at the virtual American Society for Reproductive Medicine 2020 Scientific Congress.
“Relugolix combination therapy represents a potential long-term treatment for women with heavy menstrual bleeding associated with uterine fibroids,” said Al-Hendy, a gynecologist and endoscopic surgeon at the University of Chicago.
Dr. Al-Hendy, who consults for the company that makes the drug, on Oct. 20 presented results showing improvement in quality of life with relugolix therapy.
“The fact that this longer-term study shows continued, persistent results at a year really gives us confidence that we’ll be able to use these drugs as a long-term therapy to treat fibroids,” Hugh S. Taylor, MD, president-elect of ASRM, said in an interview. Dr. Taylor, a professor and chair of ob.gyn. and reproductive sciences at Yale University, New Haven, Conn., was not involved in the study.
“A drug like this is so necessary,” Dr. Taylor continued. “We don’t have any other drugs on the market approved for long-term use.”
Relugolix is an oral gonadotropin-releasing hormone (GnRH) receptor antagonist under investigation for long-term management of uterine fibroids. The once-daily combination therapy includes 40 mg relugolix, 1 mg estradiol, and 0.5 mg norethindrone acetate.
Extension study shows prolonged benefits
The extension trial enrolled women aged 18-50 years who were experiencing heavy menstrual bleeding from uterine fibroids and who completed the 24-week phase 3, double-blind, placebo-controlled LIBERTY 1 or 2 trials. Heavy menstrual bleeding was defined as bleeding in which at least 80 mL of blood was lost per cycle for two cycles or 160 mL was lost during one cycle. Ultrasound imaging was used to confirm the presence of fibroids.
In LIBERTY 1 and 2, women were randomly assigned to receive relugolix combination therapy, placebo, or relugolix alone for 12 weeks followed by combination therapy for the remaining 12 weeks (delayed group). Those trials found that relugolix combination therapy was effective through 6 months in reducing menstrual blood loss and pain in women with uterine fibroids without loss of bone mineral density.
LIBERTY 3 extended the trial to 52 weeks, with all participants receiving relugolix combination therapy.
As in the earlier trials, the primary endpoint was reduced menstrual blood loss. By the end of the study, women needed to have at least a 50% reduction in blood loss from the initial study’s baseline while maintaining a blood loss of <80 mL. The investigators also evaluated the mean percentage of menstrual blood loss reduction, amenorrhea rate, and improvements in anemia as secondary endpoints and assessed changes in bone mineral density.
The extension study enrolled 78% (n = 477) of the 610 women who completed the initial study; of those, 363 women completed the extension study.
Among the 163 women who began with relugolix combination therapy in the first two trials, 87.7% met the primary endpoint in a per-protocol analysis through week 52. The proportion of responders in the extension study was 75.6% among the group that formerly received placebo (n = 164) and 79.9% in the delayed group (n = 149).
The overall average reduction in menstrual blood volume was 89.9%. Most of the women experienced amenorrhea at the end of the year: 70.6% in the relugolix group, 57.9% in the group that formerly received placebo, and 68.5% in the delayed group.
Reductions in uterine volume and uterine fibroid volume were also sustained from week 24 to week 52. For the relugolix combination therapy group, the mean loss of uterine fibroid volume from baseline was 13.5% at week 24 and 18.3% at week 52. Similarly, the delayed group’s average loss in fibroid volume was 28.1% at week 24 and 33.9% at week 52. The placebo group, which only had a 7% loss in fibroid volume at week 24, had an 18.4% loss in volume from baseline at week 52.
Among patients with anemia, defined as hemoglobin concentrations of <10.5 g/dL at baseline, 59% of those in the original relugolix group saw an improvement of at least 2 g/dL hemoglobin. The women’s improvement in pain symptoms also continued through week 52, with a 51.3-point reduction in scores on the bleeding pain and discomfort scale from baseline to the end of the study.
Adverse events were the same in the extension study and in the initial study. Those most commonly reported were headache and hot flashes. No serious safety signals occurred. The average reduction in bone mineral density was 0.80% at week 52, indicating no concerning loss.