Conference Coverage

Continuation of natalizumab treatment reduces risk of MS relapses during pregnancy



For women with multiple sclerosis (MS), continuing treatment with natalizumab during pregnancy and post partum is associated with a decreased risk of relapses during pregnancy, compared with washout and early treatment cessation, according to research presented at the annual congress of the European Committee for Treatment and Research in Multiple Sclerosis. Continuation of treatment is not associated with major fetal risks.

Pregnancy influences the choice of treatment for patients with MS. Not all therapies are compatible with pregnancy; the newer, more effective treatments in particular may pose risks in this regard. “There is a need to accumulate new data on how to manage our highly active patients with MS – in particular, patients who are treated with natalizumab,” said Doriana Landi, MD, PhD, a research fellow at the University of Rome Tor Vergata.

Data suggest that suspension of natalizumab before pregnancy is associated with significant disease worsening. In 2018, Portaccio et al. found that suspending natalizumab treatment before conception is associated with a higher risk of relapses during pregnancy (Neurology. 2018 Mar 6;90[10]:e832-9). Suspending natalizumab treatment at conception, however, reduced the risk of relapse by a factor of three. Other data have suggested that continuing natalizumab treatment until the 30th week of gestation could protect mothers and guarantee fetal safety.

Comparing two cohorts of women with MS

To investigate this question further, Dr. Landi and colleagues investigated a cohort of 29 women with MS who were receiving natalizumab and became pregnant. They compared this cohort’s outcomes with those of the cohort that Portaccio et al. had studied. The investigators categorized participants in both cohorts into three groups according to the time of their last infusion of natalizumab in relation to their last menstrual period. Group 0 had their last infusion before their last menstrual period, group 1 had their last infusion during the first trimester of pregnancy, and group 2 continued treatment after the first trimester. All women restarted natalizumab post partum and had at least 12 months of follow-up after delivery.

Dr. Landi and colleagues calculated the annualized relapse rate during pregnancy and during 12 months post partum for all groups. They also compared the outcomes of newborns between groups.

Prematurity may have influenced rate of hematologic complications

In all, the researchers analyzed 90 completed pregnancies in 86 women with MS. There were no significant demographic differences between groups. The overall population’s mean age was approximately 31 years, and its median Expanded Disability Status Scale (EDSS) score was about 2. The women gave birth to 94 newborns. Mean gestational age was 38.42 weeks, mean birth weight was 2,878.08 mg, and mean length was 48.23 cm.

Group 0 included 31 patients, group 1 included 30 patients, and group 2 included 28 patients. The median interval between the last dose of natalizumab and last menstrual period was 70 days for group 0, 21 days for group 1, and 197 days for group 2. Group 2 received a median of five natalizumab infusions during pregnancy, with a median interval of 80 days between the last prepartum dose and delivery. The median interval between last prepartum dose and the first postpartum dose was 411 days in group 0, 288 in group 1, and 103 in group 2.

Most pregnancies in group 2 were exposed to natalizumab for at least 28 weeks of gestation. Women in group 2 restarted natalizumab treatment significantly earlier, compared with women in the other groups.

Group 0 had a significantly increased ARR during and after pregnancy, compared with the other groups, and group 2 had the lowest ARR during pregnancy. The mean ARR during pregnancy was 1.06 in group 0, 0.49 in group 1, and 0.09 in group 2. The ARR decreased to 0 in pregnancies exposed to natalizumab for more than 90 days. The mean ARR post partum was 0.39 in group 0, 0.23 in group 1, and 0.10 in group 2. Women in group 0 and group 1 had a higher EDSS during pregnancy than before conception.

Newborns’ mean gestational age, birth weight, and length did not differ significantly between groups. Five newborns in group 2, three of whom were premature, had anemia. This outcome is consistent with previous findings, and prematurity may be a confounding factor, said Dr. Landi. The frequency of birth defects was higher in group 2 than in the other groups, but most of them occurred in one twin, said Dr. Landi. The investigators observed malformations in one group 0 newborn (minor), four group 1 newborns (five minor and one major), and four (two minor and four major) group 2 newborns.

In pregnancy during which natalizumab treatment is prolonged until the third trimester, treatment should be restarted after delivery within 2 weeks of the last infusion to avoid potential doubled rebound, said Dr. Landi. Future studies should examine whether extended dosing is as effective as regular dosing. A larger sample size is needed to estimate risks correctly for newborns in exposed pregnancies and counsel patients appropriately.

Dr. Landi reported receiving travel funding from Biogen, Merck Serono, Sanofi-Genzyme, and Teva; honoraria for speaking from Sanofi-Genzyme and Teva; and consultation fees from Merck Serono and Teva. She is an investigator in clinical trials being conducted for Biogen, Merck Serono, Novartis, Roche, and Teva.

SOURCE: Landi D et al. ECTRIMS 2019, Abstract 338.

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