Extension study showed sustained efficacy
The study by Al-Hendy and colleagues showed that the relugolix combination not only was well tolerated but also that there was sustained improvement in heavy bleeding, with the average patient having an approximately 90% decrease in menstrual bleeding from baseline.6 It was noted that 70.6% of patients achieved amenorrhea over the last 35 days of treatment.
Importantly, the treatment effect was independent of race, body mass index, baseline menstrual blood loss, and uterine fibroid volume. The bone mineral density (BMD) change trajectory was similar to what was observed in the pivotal study. No new safety concerns were identified, and BMD generally was preserved.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
The extension study by Al-Hendy and colleagues demonstrated that that the reduced fibroid-associated bleeding treated with relugolix combination therapy is sustained throughout the 52-week period, with no new safety concerns.
The extension study by Al-Hendy and colleagues demonstrated that that the reduced fibroid-associated bleeding treated with relugolix combination therapy is sustained throughout the 52-week period, with no new safety concerns.
Linzagolix is the newest GnRH antagonist to be studied in a randomized, placebo-controlled trial
Donnez J, Taylor HS, Stewart EA, et al. Linzagolix with and without hormonal add-back therapy for the treatment of symptomatic uterine fibroids: two randomised, placebo-controlled, phase 3 trials. Lancet. 2022;400:896-907.
At the time of this writing, linzagolix was not approved by the FDA. The results of the PRIMROSE 1 (P1) and PRIMROSE 2 (P2) trials were published last year as 2 identical 52-week randomized, parallel, double-blind, placebo-controlled, phase 3 trials.7 The difference between the development of linzagolix as a GnRH antagonist and other similar medications is the strategy of potential partial hypothalamic pituitary ovarian axis suppression at 100 mg versus complete suppression at 200 mg. In this trial by Donnez and colleagues, both linzagolix doses were evaluated with and without add-back hormonal therapy and also were compared with placebo in a 1:1:1:1:1 ratio.7
Study details and results
To be eligible for this study, participants had to have heavy menstrual bleeding, defined as more than 80 mL for at least 2 cycles, and have at least 1 fibroid that was 2 cm in diameter or multiple small fibroids with the calculated uterine volume of more than 200 cm3. No fibroid larger than 12 cm in diameter was included.
The primary end point was a menstrual blood loss of 80 mL or less and a 50% or more reduction in menstrual blood loss from baseline in the 28 days before week 24. Uterine fibroid volume reduction and a safety assessment, including BMD assessment, also were studied.
In the P1 trial, which was conducted in US sites, the response rate for the primary objective was 56.4% in the linzagolix 100-mg group, 66.4% in the 100-mg plus add-back therapy group, 71.4% in the 200-mg group, and 75.5% in the 200-mg plus add-back group, compared with 35.0% in the placebo group.
In the P2 trial, which included sites in both Europe and the United States, the response rates were 56.7% in the 100-mg group, 77.2% in the 100-mg plus add-back therapy group, 77.7% in the 200-mg group, and 93.9% in the 200-mg plus add-back therapy group, compared with 29.4% in the placebo group. Thus, in both trials a significantly higher proportion of menstrual reduction occurred in all linzagolix treatment groups compared with placebo.
As expected, the incidence of hot flushes was the highest in participants taking the linzagolix 200-mg dose without add-back hormonal therapy, with hot flushes occurring in 35% (P1) and 32% (P2) of patients, compared with all other groups, which was 3% to 14%. All treatment groups showed improvement in quality-of-life scores compared with placebo. Of note, to achieve reduction of fibroid volume in the 40% to 50% range, this was observed consistently only with the linzagolix 200-mg alone dose.
Linzagolix effect on bone
Decreases in BMD appeared to be dose dependent, as lumbar spine losses of up to 4% were noted with the linzgolix 200-mg dose, and a 2% loss was observed with the 100-mg dose at 24 weeks. However, these were improved with add-back therapy. There were continued BMD decreases at 52 weeks, with up to 2.4% with 100 mg of linzagolix and up to 1.5% with 100 mg plus add-back therapy, and up to 2% with 200 mg of linzagolix plus add-back therapy. ●
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Results of the P1 and P2 trials suggest that there could be a potential niche for linzagolix in patients who need chronic use (> 6 months) without the need for concomitant add-back hormone therapy at lower doses. The non-add-back option may be a possibility for women who have both a contraindication to estrogen and an increased risk for hormone-related adverse events.
Results of the P1 and P2 trials suggest that there could be a potential niche for linzagolix in patients who need chronic use (> 6 months) without the need for concomitant add-back hormone therapy at lower doses. The non-add-back option may be a possibility for women who have both a contraindication to estrogen and an increased risk for hormone-related adverse events.