Natalizumab

Recombinant humanized IgG4k monoclonal antibody that blocks the human integrin alpha-4 subunit making it difficult for T lymphocytes to pass through the meninges.
Its use is approved in the treatment of severe forms of multiple sclerosis (EMA 2017) and in Crohn's disease when resistant to other treatments (Yarur 2013, FDA 2012).
Administration by intravenous infusion every 4 weeks.

Its very high molecular weight explains the small or zero transfer into milk observed (Ciplea 2020, Matro 2018, Hainke 2015, Baker 2015), since molecules of more than 800 - 1,000 Da do not pass into breast milk (Hale, Almas 2016, Anderson 2016).
No problems have been observed in infants of mothers treated with this drug (Ciplea 2020).

Null or negligible passage into breast milk of similar monoclonal antibodies, such as adalimumab, belimumab, certolizumab, golimumab, infliximab, ipilimumab, rituximab, tocilizumab and ustekinumab has been confirmed (Bar-Gil 2021, LaHue 2020, Saito 2020, 2019 and 2018, Krysko 2019, Whittam 2019, Klenske 2019, Matro 2018, Anderson 2018, Bragnes 2017, Witzel 2014, Ross 2014, Fritzsche 2012).

Due to its protein nature, it is inactivated in the gastrointestinal tract without being absorbed (practically nil oral bioavailability) and this hinders or prevents its passage into the infant´s plasma from ingested breast milk (Lactmed, Rademaker 2018, Bragnes 2017, Götestam 2016 , Witzel 2014, Butler 2014, Mervic 2014) except for premature infants and during the immediate neonatal period when there might be a greater intestinal permeability (Sammaritano 2020).

No problems have been detected in infants whose mothers received other similar monoclonal antibodies such as belimumab, bevacizumab, infliximab, rituximab, tocilizumab, or ustekinumab (Bar-Gil 2021, LaHue 2020, Saito 2020, 2019 and 2018, Klenske 2019, Mugheddu 2019, Krysko 2019, Matro 2018, Bragnes 2017, Hyrich 2014, Danve 2014).

Expert authors consider that the use of this and other monoclonal antibodies during breastfeeding is safe or very likely to be safe (Whittam 2019, Matro 2018, Anderson 2018 and 2016, Witzel 2014, Pistilli 2013).

Given the strong evidence that exists on the benefits of breastfeeding and the development of babies and the health of their mothers, it might be appropriate to evaluate the risk-benefit of any maternal treatment, including chemotherapy, and counsel individually each mother who wishes to continue breastfeeding (Koren 2013).

See below the information of these related products:

• Maternal Inflammatory bowel disease (IBD) (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)
• Maternal Multiple Sclerosis (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)