SUMMARY: Natalizumab is a recombinant humanised anti-α4-integrin antibody licensed for the treatment of highly active relapsing remitting multiple sclerosis.
A critical step in the inflammatory process underlying multiple sclerosis (MS) pathology involves immune cell trafficking into the CNS via the blood–brain barrier. The presence of the protein α4-integrin on the surface of immune system lymphocytes is integral to assisting such diffusion. Treatment with natalizumab thereby inhibits the activity of the protein, reducing the rate of lymphocyte transfer into the CNS.
There are currently limited data available which provide evidence of the safety of natalizumab use during pregnancy. However, the available data do not indicate an increased risk of adverse pregnancy outcome.
Use of natalizumab amongst non-pregnant patients has been associated with an increased risk of developing progressive multifocal leukoencephalopathy (PML) as a result of reactivation of the commonly carried dormant Polyomavirus JC. Given that maternal physiological immunosuppression occurs naturally during pregnancy, an increased risk of maternal PML may exist amongst pregnant patients taking natalizumab. The subsequent transmission of the Polyomavirus JC to the fetus may be of further concern. Due to the limited experience of natalizumab use in pregnancy, data investigating both the risk of PML development amongst pregnant patients, and the risk of viral transmission to the fetus is currently unavailable.
Where natalizumab use is required during pregnancy, close monitoring of maternal neurological function is advised. Should maternal symptoms of PML present during pregnancy, enhanced fetal and neonatal monitoring may also be warranted.
Please report ALL cases of drug and/or chemical exposure in pregnancy to UKTIS by telephoning the service on 0844 892 0909 or by printing and completing a pregnancy reporting form, providing as many patient identifiers as possible to enable follow up of pregnancy outcome. This vital information enables UKTIS to provide evidence-based advice for future enquiries and to conduct surveillance of potential and known teratogens.
For case specific advice please contact UKTIS on 0844 892 0909.