New safety data of anti-CD20 mAbs around pregnancy

B-cell-depleting, anti-CD20 monoclonal antibodies (mAbs) such as ocrelizumab may be safe when used before or during the first trimester of pregnancy and/or during lactation, a new study suggested. Anti-CD20 mAbs do not seem to have a depleting effect on the physiological B-cell development in exposed infants. Exposure in the second or third trimester can lead to B-cell depletion.

Data on the reduction of B cells in newborns after different exposure windows of anti-CD20 mAbs before or during pregnancy or breastfeeding are extremely scarce. As a result, anti-CD20 mAbs have a very conservative label regarding pregnancy, which is impractical in daily practice and increases the risk of disease progression in the mother.

Prospective data, presented by Dr Carolin Schwake (Ruhr-University Bochum, Germany), included results from 44 infants (22 girls and 22 boys) who were exposed to anti-CD20 mAbs before or during pregnancy and the lactation period, or only during lactation. B-cell counts and adverse effects of the 44 infants were analysed [1].

Results indicated that 41 infants were exposed before or during pregnancy (33 to ocrelizumab and 6 to rituximab) and during lactation (1 to rituximab and to 3 ocrelizumab). The average time interval between anti-CD20 mAbs exposure and the last menstrual period was 49.6 days if administered before pregnancy (n=33) and 44 days if administered during pregnancy (n=8). B-cell analysis of the newborns was done on average 19 days postpartum. Mean postnatal B-cell values were within the normal range (782.6 ± 440.7/µL; 15.9 ± 6.8%). In 2 cases, ocrelizumab exposure in the second and third trimesters of pregnancy resulted in complete B-cell depletion, but complete repopulation was seen after 2 months of follow-up. There were no congenital malformations or severe infections during the first year of life. In 3 cases, exposure was limited to lactation (1 ocrelizumab, 2 ofatumumab). This had no effect on the B-cell count of the infants (1,121.7 ± 50.5/µL).

Dr Schwake concluded that active attempts of conception can be planned shortly after infusion/injection of anti-CD20 mAbs. In the second or third trimester, these drugs can cross the placenta and result in B-cell depletion in the infant. During this period, exposure should therefore be monitored and live vaccines postponed.

1. Schwake C. Effects of anti-CD20 therapies on infant health and physiological B-cell development if administered before or during pregnancy and/or lactation. Abstract O036, ECTRIMS 2022, Amsterdam, 26–28 October, the Netherlands.

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Posted on 20 December 202229 February 2024