Miscarriage or Ectopic Pregnancy Not More Likely in Women Using Rebif, Study Suggests

Results from a large observational study of pregnant women with multiple sclerosis (MS) treated with an interferon (IFN) beta-1a, like Rebif, before and during the first trimester showed no elevated risk of a miscarriage or ectopic pregnancy compared to those not using the medicine.

This finding was presented at the recent European Academy of Neurology (EAN) 2019 Congress in Oslo, based on Finnish and Swedish health registry data collected between 1996 and 2014.

Rebif (marketed by EMD Serono in the U.S. and Canada, and by Merck KGaA elsewhere) is a disease-modifying treatment for relapsing forms of MS. It is currently contraindicated during pregnancy by the European Medicines Agency (EMA). In the U.S., none of the disease-modifying medications available — including Rebif — are approved during pregnancy, and women taking these medications are instructed to discuss plans to become pregnant with their prescribing physician.

“MS predominantly affects women in their 20’s and 30’s, when many are considering starting a family. Knowing what might happen if exposed to a disease-modifying treatment during pregnancy is extremely important,” Kerstin Hellwig, MD, a professor at department of neurology at St. Josef Hospital in Germany, said in a press release.

The observational study involved 2,444 pregnancies with known outcomes, including 797 pregnant women who were treated with IFN beta, and 1,647 women who were not.

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No statistical difference in the prevalence of spontaneous abortions was recorded between the two groups: 8.3% of the IFN beta-exposed pregnant women had spontaneous abortions, compared with 12% of those who were not.

Regarding ectopic pregnancy (when the embryo attaches outside the uterus), 1.6% of IFN beta-exposed pregnant women had this complication, compared with 3.2% among unexposed women. In fact, a numerically lower risk was observed among those with IFN beta exposure.

It is important to point out that this was an observational study, and these types of studies tend to have methodologic limitations, so their potential for bias is higher.

Merck has submitted regulatory filings with different health authorities to include safety data from these interferon registries in the Rebif label, which sets out how a medicine might be used and in which groups of patients.

“Our company has long been committed to providing treatment options and addressing the unmet needs of the MS patient community. The results of this study augment our knowledge of the benefits and risks of Rebif gathered over more than two decades,” said Maria Rivas, MD, chief medical officer at Merck.