Ebopiprant add-on to atosiban delays preterm birth

Adding ebopiprant to atosiban may delay delivery for at least 48 hours in women with spontaneous preterm labour, according to the PROLONG* study presented at RCOG 2021.

“Ebopiprant (OBE022) is a novel, oral and selective prostaglandin F2α (PGF2α) receptor antagonist being developed to delay preterm birth,” said lead author Dr Ben Willem Mol from Monash University in Melbourne, Australia.

“Treatment of spontaneous preterm labour aims to delay delivery at least 48 hours in order to administer ss for foetal lung maturation and antenatal transfer to centre with neonatal intensive care,” he added.

This proof-of-concept, double-blind, placebo-controlled trial analysed 113 women with threatened preterm labour (gestational age 24–34 weeks) who were randomized to receive either ebopiprant 1,000 mg followed by 500 mg twice daily (n=58; mean age 29.7 years) or placebo (n=55; mean age 29.6 years) for 7 days in addition to atosiban. Patients were followed up for 14 days and, after delivery, both mother and neonates were followed up until 2 years. [RCOG 2021, abstract 601]

Most of the participants had singleton pregnancies, at a rate of 72.4 percent and 74.5 percent in the ebopiprant and placebo groups, respectively, while 27.6 percent and 25.5 percent had twin pregnancies.

Overall, fewer patients treated with ebopiprant delivered within 48 hours of starting treatment than those treated with placebo (12.5 percent vs 21.8 percent; odds ratio [OR], 0.52).

A lower percentage of patients who had singleton pregnancies delivered within 48 hours of starting treatment was also observed in the ebopiprant group than the placebo group (12.5 percent vs 26.8 percent; OR, 0.39), but not in patients with twin pregnancies (12.5 percent vs 7.1 percent; OR, 2.05).

Singletons who were delivered within 7 days after randomization was also less common in the ebopiprant group vs the placebo group (27.5, percent vs 31.7 percent, respectively; OR, 0.81).

However, the percentage of patients who delivered after at least 37 weeks of gestation did not differ between the ebopiprant and placebo groups (66.1 percent vs 60.0 percent; OR, 1.29).

The rates of treatment-emergent adverse events were comparable between the ebopiprant and the placebo treatment groups (41.4 percent vs 41.8 percent). “We did not see any maternal and foetal safety concerns, and side effects were as expected, normal, and mild,” said Mol.

Neonatal vital signs, pregnancy outcomes, and hospital admission did not differ between the treatment groups, Mol noted.

“[This] PROLONG trial provides initial evidence that … in women with preterm labour, ebopiprant added to atosiban infusion reduces the probability of delivering within 48 hours, … [particularly in] singleton pregnancies,” Mol concluded.

“These results and findings should be confirmed in larger trials, that we are currently planning,” he noted.

*PROLONG: PoC Study of OBE022 in Threatened Preterm Labour