Can Natalizumab be Continued in Multiple Sclerosis Patients into Early Pregnancy?

Two studies published in the Neurology evaluated the maternal and fetal consequences of stopping the monoclonal antibody natalizumab in women with multiple sclerosis either well before pregnancy or within the first few days of the pregnancy. The studies evaluated 92 pregnancies. In the study that evaluated the maternal risks:

• The relapse rate of multiple sclerosis during and after the pregnancy was three times higher (37%) in the women that discontinued natalizumab than those who never received it (10%).
• The relapses were particularly more common during the first three months of pregnancy and following delivery.
• The relapses were more common if natalizumab was stopped earlier during pregnancy.
• The number of relapses following the delivery appeared to be lesser with the early re-introduction of disease modifying drugs following the delivery.

In the study that evaluated fetal risks, women with multiple sclerosis who continued to use natalizumab up to the first trimester were included. Most of these women stopped the drug within a week of the pregnancy. The scientists found that:

• The rate of spontaneous abortions (miscarriage) was four times higher than what occurred in women with multiple sclerosis who received interferon or no treatment during pregnancy. The risk of 17.4% that occurred in these women was, however, similar to that in the general population (14%).
• The risk of congenital abnormalities in the babies of 3.7%, was again similar to that of the general population.
• Exposure to natalizumab and interferon-β was associated with lower length and weight of the babies.

The two studies indicate that by delaying the discontinuation of natalizumab to just before pregnancy and the early resumption of treatment following the delivery could be associated with lower risk of relapse in women. More evidence is required on the development of congenital abnormalities on the baby if the drug is stopped late. The study did not report the severity of the relapses, which could throw more light on the issue.

About Natalizumab

Natalizumab is used for the treatment of multiple sclerosis in those patients who do not respond to or are unable to tolerate other medications. Multiple sclerosis is a condition where antibodies attack the covering of nerves, eventually resulting in nerve damage.

Natalizumab acts on the immune system and prevents the damage to the nervous system. A single dose is administered intravenously every 4 weeks. It is also used for the treatment of Crohn’s disease. Adverse effects include headache fatigue, depression, skin rash, digestive tract problems, infection, and bone and joint pain. Possible serious adverse effects include a brain infection called progressive multifocal leukoencephalopathy, liver damage, allergic reaction, and herpes infection. Interferon beta is currently used for the treatment of multiple sclerosis during pregnancy.

References:

1. Portaccio E et al. Pregnancy decision-making in women with multiple sclerosis treated with natalizumab I: Fetal risks. Neurology Feb 2018. DOI: 10.1212/WNL.0000000000005067
2. Portaccio E et al. Pregnancy decision-making in women with multiple sclerosis treated with natalizumab II: Maternal risks. Neurology Feb 2018. DOI: 10.1212/WNL.0000000000005068

Source-Medindia