Fusion of IgG antibodies to albumin inhibits transport across the placenta.

Fusion of IgG antibodies to albumin significantly reduces transplacental transport, decreasing fetal exposure in mouse and human placental models.

• Why it matters: Limiting fetal transfer of therapeutic antibodies is crucial during pregnancy to prevent potential adverse effects, yet current methods do not effectively address this challenge.
• What they did: The study used mouse models and ex vivo human placental perfusion systems to compare transport of IgG fused to albumin versus unmodified IgG, demonstrating a marked reduction in fetal transfer.
• The result: Albumin fusion preserved FcRn-mediated half-life extension while minimizing fetal antibody transfer, offering a promising strategy to enhance the safety of biologics during pregnancy.