Is Anifrolumab safe while breastfeeding?

Summary of use during breastfeeding

Anifrolumab concentration in milk was very low in one mother, consistent with it being a large protein molecule with a molecular weight of 148,000 Da.[1] It is also likely to be partially destroyed in the infant’s gastrointestinal tract and absorption by the infant is probably minimal.[2] An infant exposed during pregnancy and breastfeeding had no adverse effects. Waiting for at least 2 weeks postpartum to resume therapy may minimize transfer to the infant.[3] Until more data become available, anifrolumab should be used with caution during breastfeeding, especially while nursing a newborn or preterm infant.

Effects on the breastfed infant

A woman who had systemic lupus erythematosus received anifrolumab (presumably 300 mg) monthly for 6 months during pregnancy, up to 30 weeks of gestation. Her infant was born at week 38+3 and was exclusively breastfed. Anifrolumab was restarted postpartum at about 1 month postpartum and breastfeeding was continued. Neonatal follow-up remained normal with no recurrent or severe infections. Routine immunizations were administered according to the recommended schedule with no adverse reactions to vaccinations. The rotavirus vaccine was postponed as a precaution because it is a live-attenuated vaccine. Electrocardiogram and growth parameters were normal. Immunological evaluation at 4, 6 and 12 months of age revealed normal complete blood count, apart from mild age-appropriate neutropenia. T-cell subsets (CD4+, naïve CD4+, and CD8+) were slightly reduced compared with age-matched reference values, but progressively increased over time without intervention. Lymphocyte proliferative responses to mitogens and tetanus toxoid were normal. Immunoglobulin levels and vaccine-specific antibody responses (hepatitis B and tetanus) were adequate. Autoimmune screening (antinuclear antibodies and anti-double-stranded DNA) was negative. The child started nursery school at 9 months of age and experienced only minor infectious episodes.[5]

Effects on milk supply

Relevant published information was not found as of the revision date.

Levels in milk

Maternal Levels. A woman with systemic lupus erythematosus was treated with prednisolone 6 to 6.5 mg, tacrolimus 4 mg, and hydroxychloroquine 300 mg daily and anifrolumab 300 mg every 4 weeks. Milk samples taken between days 1 and 14 after resuming anifrolumab postpartum ranged from 0.01 to 0.11 mg/L, with the highest concentration 4 days after the dose.[4]

Infant Levels. Relevant published information was not found as of the revision date.