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Observational Study
. 2025 Mar;31(3):338-351.
doi: 10.1177/13524585241307165. Epub 2025 Jan 6.

Ofatumumab-exposed breastfeeding in multiple sclerosis patients

Laura Witt  1   2 , Karen Dost-Kovalsky  1 , Natalia Friedmann  1 , Nadine Bast  1   2 , Sabrina Haben  1 , Theresa Oganowski  1 , Ralf Gold  1 , Kerstin Hellwig  1 , Sandra Thiel  1
Affiliations
Observational Study

Ofatumumab-exposed breastfeeding in multiple sclerosis patients

Laura Witt et al. Mult Scler. 2025 Mar.

Abstract

Background: In Europe, ofatumumab is approved for breastfeeding, but data on its transfer into breast milk and clinical experience are lacking.

Objective: To analyze (1) health, development, and adverse events after live vaccination of ofatumumab-exposed breastfed infants and (2) detectability of ofatumumab in breast milk, and to calculate the relative infant dose (RID) using two methods, the traditional method and a second method considering maternal exposure to multiple ofatumumab doses and extended collection period.

Methods: In this observational study, clinical data were collected by standardized telephone interviews up to 2 years postpartum. Breastmilk samples were analyzed by enzyme-linked immunosorbent assay.

Results: Twelve mothers started ofatumumab-exposed breastfeeding between 0.6 and 19.6 months postpartum. Infants showed neither abnormalities in infections, antibiotic use, or hospitalizations nor developmental delay. Five infants with available B cells had normal levels. Eight (66.7%) infants received live vaccines during/after exposed breastfeeding. None had complications. Ofatumumab concentration in breast milk varied widely between a median RID of average concentration 0.027% (range: 0.019%-0.115%) using method 1 and 2.912% (range: 1.301%-12.322%) using method 2.

Conclusion: Ofatumumab-exposed breastfeeding did not adversely affect infants' health or development. Despite higher RIDs using the more appropriate method 2, the risk of substantial antibody absorption by infants appears to be low.

Keywords: Multiple sclerosis; breast milk concentration; breastfeeding; infant development; ofatumumab; relative infant dose.

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Conflict of interest statement

Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: L.W. has received travel grants from Novartis Pharma GmbH. S.H., T.O., and K.D.-K. have nothing to disclose. N.F. has received speaker honoraria and a sponsorship for congress participation from Biogen GmbH. N.B. has received payment for manuscript writing from Thieme. R.G. has received speaker honoraria and research support from Bayer-Schering Healthcare, Biogen-Idec Germany, Chugai, Eisai, Merck Serono, Nikkiso Pharma, Novartis, Roche, Sanofi Genzyme, and TEVA, has received consulting honoraria from CSL Behring, Baxter, Janssen and Talecris and has stock options in Bayer, Merck, and Roche. K.H. has received speaker honoraria and research support from Bayer, Biogen, Merck, Novartis, Sanofi Genzyme, Roche, and Teva, has received support for congress participation from Bayer, Biogen, Merck, Roche, Sanofi Genzyme, and Teva, and has served on scientific advisory boards for Bayer, Biogen, Sanofi, Teva, Roche, Novartis, and Merck. S.T. has received speaker honoraria from Bayer Healthcare and Biogen GmbH as well as payment for manuscript writing from HEXAL AG.

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