STOCKHOLM —  Among women with active relapsing-remitting multiple sclerosis (RRMS), continuation of natalizumab (NTZ) treatment until the end of the first trimester is associated with significantly reduced disease reactivation compared with stopping NTZ at conception, according to study results presented at the 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS), held September 11-13, 2019 in Stockholm, Sweden.

The treatment in women with active RRMS who wish to become pregnant poses a medical and ethical challenge. The goal of this study was to assess the benefits and risks of a couple of treatment strategies for these women: NTZ continuation until conception and continuation of NTZ until the end of the first trimester.

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The study cohort included 46 pregnancies of women with active RRMS treated at the university hospital of Marseille, France. In women with anti-JC virus antibody index <1.5, NTZ was recommended until the end of the first trimester (“secured first trimester,” 30 women). Continuation of NTZ until conception (“secured conception,” 16 women) was used when patients refused to continue the treatment during pregnancy.

The relapse risk during pregnancy was lower among women who continued NTZ until the end of the first trimester compared with those who stopped treatment at conception (3.6% vs 38.5%, respectively; P <.005). The only predictor of relapse during pregnancy assessed through stepwise multivariable logistic regression model was time of NTZ discontinuation (secured first trimester vs secured conception; P <.005; β =.25).

Risk for disability progression was lower with secured first trimester vs secured conception approach (3.6% vs 30.8%; P <.05). The only predictor of disability progression during pregnancy was time when NTZ was stopped (P <.05; β, 0.19).

Spontaneous abortions were documented in 3 pregnancies when NTZ was stopped at conception, and in 2 pregnancies when NTZ was continued until the end of the first trimester. No newborn showed abnormal morphological measures.

“Maintenance of natalizumab until the end of the first trimester dramatically reduces the risk of disease reactivation during pregnancy in women with active RRMS. This strategy must be carefully discussed with the mother due to lack of comprehensive data on fetal safety,” concluded the researchers.

Reference

Demortiere S, Rico A, Boutiere C, Maarouf A, Pelletier J, Audoin B. What is the best time to stop natalizumab in patients with active RRMS planning pregnancy? Poster presentation at: 35th Congress of the European Committee for Treatment and Research in Multiple Sclerosis; September 11-13, 2019; Stockholm, Sweden. Abstract P781.