FDA advisory committee narrowly backs withdrawal of approval for AMAG's preterm birth drug Makena

AMAG Pharmaceuticals said that nine members of an FDA advisory committee voted to withdraw marketing clearance of Makena (hydroxyprogesterone caproate), while seven panel members voted to leave the product on the market under accelerated approval and require a new confirmatory trial. Shares in the company fell as much as 26% on the news.

Makena gained approval in 2011 to reduce the risk of preterm delivery before 37 weeks of pregnancy, in women with a history of spontaneous preterm birth. AMAG obtained Makena in 2014 as part of its purchase of Lumara Health, although the company announced earlier this year that the confirmatory PROLONG study of the drug in patients with a history of a prior spontaneous singleton preterm delivery failed to meet its co-primary endpoints.

"We are disappointed with the nearly split vote on this key question and we are committed to working with the FDA to identify feasible ways to generate additional efficacy data on Makena," remarked AMAG chief medical officer Julie Krop. The company noted that it agreed with several committee members "who voiced concern that withdrawal of Makena would leave providers with no safe treatment options for pregnant women."

Approval of Makena was based on study results showing that 37% of women aged 16 to 43 years of age who were pregnant with a single foetus and had a previous spontaneous preterm birth gave birth before 37 weeks, compared to 55% in the control group. Meanwhile, in the PROLONG trial, the incidence of preterm delivery at less than 35 weeks was 11% in the Makena group versus 11.5% for placebo.

Panel member Deborah Wing remarked "I struggled with my vote, but I had to look only at the data." The advisory committee voted unanimously that the PROLONG study showed no benefit, while only three members voted that the combined results of both trials showed substantial effectiveness. AMAG said that it will comment further on the advisory committee vote during its third-quarter financial results conference call on November 1.

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