B-cell Counts in Pregnancy Exposed Ofatumumab Neonates of Women with Multiple Sclerosis
Karen Dost-Kovalsky1, Nadine Bast1, Sabrina Haben1, Nina Blum1, Natalia Friedmann1, Theresa Oganowski1, Ralf Gold1, Sandra Thiel1, Kerstin Hellwig1
1Neurology, St Josef Hospital
Objective:
To assess the effect of pregnancy exposure to ofatumumab on B-cell counts of neonates immediately after birth
Background:

Ofatumumab is not approved for use during pregnancy, with current recommendations stating that effective contraception be used up to 6-months before conception. Offspring are potentially at risk of B-cell depletion, reduced immunity and the consequence of delaying vaccination with live vaccines.

Design/Methods:
11 Pregnancies with ofatumumab exposure, documented in the German Multiple Sclerosis and Pregnancy Registry are presented. Exposure was defined as ofatumumab use after the first day of the last menstrual period (LMP) or within 6-months prior to LMP. B-cell counts were collected from laboratory reports of umbilical cord and postpartum blood samples 
Results:

11 pregnancies with median exposure duration of 15 days after LMP (Range: -94 to 47days) were inlcuded. 18.2%(2/11) were exposed in the 4-weeks prior to LMP and 72.7%(8/11) after LMP.

Neither B-cell depletion nor lymphopenia were detected with median B-cell counts of 700/μl(Range: 588/μl -2589/μl) and median absolute B-cell counts of 14%(5%-33.3%), as the percentage of lymphocytes. 72.7%(8/11) had umbilical cord blood analysed while 27.2%(3/11) of children had blood taken within 43 days postpartum. 30%(3/10) of children had an infection within the first 6-months postpartum including: covid-19, respiratory syncytial virus and a urinary tract infection. 30%(3/10) of children received the rotavirus attenuated live vaccine at a median of 58 days postpartum (Range: 56-71). One child (33.3%) developed respiratory syncytial virus post vaccination. For one child, no postpartum follow-up was available.

Conclusions:

Neither B-cell depletion nor reduction was detected in our cohort of neonates among women exposed to ofatumumab in pregnancy or within the 6-months prior. Our data adds to the growing base of B-cell counts of neonates exposed to anti-CD20 therapy during early pregnancy with generally healthy newborns, not at increased risk of infection and without the need to postpone vaccination  

10.1212/WNL.0000000000210623
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