Novel GnRH Antagonist Reduces Heavy Menstrual Bleeding in Uterine Fibroids Study

Linzagolix is a novel, oral gonadotropin-releasing hormone (GnRH) receptor antagonist, the trial assessed the treatment in 535 women.

A phase 3 trial investigating linzagolix for the treatment of heavy menstrual bleeding (HMB) due to uterine fibroids met its primary and secondary efficacy end points, according to ObsEva, a biopharmaceutical company developing the treatment. 

Linzagolix is a novel, oral gonadotropin-releasing hormone (GnRH) receptor antagonist. In the PRIMROSE 2 study, 535 women with HMB due to uterine fibroids were randomized to receive either 100mg or 200mg daily of linzagolix or placebo, with and without hormonal add-back therapy (ABT). 

Results showed that 93.9% (P <.001) of the 200mg group with ABT, 56.7% (P <.001) of the 100mg group without ABT, and 29.4% of the placebo group were found to be responders, defined as those with menstrual blood loss volume of ≤80mL and ≥50% reduction from baseline menstrual blood loss volume at 24 weeks (measured using alkaline hematin method). Both doses achieved clinically relevant secondary end points including amenorrhea (P <.001), reduction in pain (P <.001), improvement in quality of life (P <.001) and improvement in hemoglobin levels (P <.002). Additionally, a significant reduction in fibroid volume was noted in the 200mg with ABT group (P <.008).

With regard to safety, adverse events occurring in >5% of patients were headache, hot flushes, and anemia, while mean percentage change from baseline in bone mineral density (BMD) was found to be similar to what has been observed in previous studies. In a dose-ranging trial, mean BMD losses at 24 weeks were <1% with 50mg and 75mg doses and up to 2.6% with the 200mg dose.

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“The full suppression 200mg dose with ABT achieved a potentially best in class, 94% responder rate,” said  Dr Ernest Loumaye, ObsEva CEO and co-founder. “Importantly, the 100mg dose without ABT with over 50% of women responding, provides a meaningful option for the significant proportion of women who cannot or do not want to take exogenous hormones. We look forward to the results from our second pivotal study, PRIMROSE 1 conducted in the US, in Q2 2020.”

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This article originally appeared on MPR