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Risk of MS relapse high when natalizumab is stopped for pregnancy

JAMA Network Open
Reuters Health - 24/01/2022 - For women with multiple sclerosis (MS) on natalizumab, there is a high risk of relapse and related disability when the drug is stopped for pregnancy, according to data from the German Multiple Sclerosis and Pregnancy Registry. 

Women with MS "need to be informed about the risks of early natalizumab cessation due to pregnancy or planned pregnancy, and treatment alternatives should be considered," write Dr. Kerstin Hellwig of Ruhr University Bochum and colleagues in JAMA Network Open. 

The magnitude of risk for relapse when natalizumab is stopped for pregnancy is unclear. 

To investigate, the researchers studied 255 women with 274 pregnancies who stopped natalizumab before pregnancy or in the first trimester. Only 13 (4.7%) used a first-line bridging disease-modifying treatment. 

During pregnancy and the first postpartum year, relapses occurred in 183 pregnancies (66.8%), severe relapses in 44 (16.1%) and potentially life-threatening relapses three (1.1%). 

Most relapses (regardless of severity) occurred during the second trimester of pregnancy and in the first three months after delivery. Severe relapses were more common during pregnancy than postpartum. Five women (1.8%) restarted natalizumab therapy during pregnancy due to a relapse. 

One year after delivery, more than 10% of women retained "clinically meaningful" disability from pregnancy-related natalizumab-cessation relapses, the researchers report. 

Neither pregnancy itself nor restarting natalizumab shortly after delivery or exclusively breastfeeding the child offered protection against relapse. However, restarting natalizumab early in the postpartum period was tied to a reduced relapse rate during the entire first postpartum year. 

"Understanding how often severe natalizumab cessation-related relapses occur in the context of pregnancy planning is crucial for informed, shared decision-making discussions," the researchers say. 

The findings from this cohort study "should be shared with women on natalizumab who desire pregnancy to weigh the high risk of pregnancy-related relapses and disability to the partly uncertain risks of continuing natalizumab throughout pregnancy or switching to depleting agents before conception," they advise. 

It should also be noted, they say, that continuing natalizumab during pregnancy shows "promising results in first studies" and this option "should be evaluated with consideration for the best time to stop natalizumab during pregnancy and restart after delivery." 

The German Multiple Sclerosis and Pregnancy Registry is partly supported by the Innovation Fund of the Federal Joint Committee, Almirall, Biogen, Teva Pharma, Novartis, Roche, and Merck. Dr. Hellwig has disclosed financial relationships with Bayer, Biogen, Merck, Novartis, Sanofi-Genzyme, Roche and Teva. 

SOURCE: https://bit.ly/3fUXRD4 JAMA Network Open, online January 24, 2022. 

By Reuters Staff 

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