AMAG’s PROLONG Trial Fails to Hit Endpoints in Preventing Preterm Births

Shares of AMAG Pharmaceuticals plunged more than 17 percent Friday after the company said its Phase III PROLONG trial of Makena failed to demonstrate a statistically significant difference from placebo in preventing preterm births. The trial examined if Makena, a progestin first approved in 2011, could benefit patients who have shown prior spontaneous singleton preterm delivery. Trial data from PROLONG (Progestin’s Role in Optimizing Neonatal Gestation) showed that Makena benefited 11 percent of patients and placebo 11.5 percent of patients in the incidence of preterm delivery at less than 35 weeks. The PROLONG trial was conducted as part of an approval commitment under the Food & Drug Administration’s “Subpart H” accelerated approval process. The PROLONG trial enrolled approximately 1,700 pregnant women, over 75 percent of which were enrolled outside the U.S. And the fact that the majority of women who participated in the trial came from outside the United States could have skewed the results, the Waltham, Mass.-based company said.