Paediatric outcomes after maternal nipocalimab for haemolytic disease of the fetus and newborn: an open-label, single-arm study

Objectives To describe haemolytic disease outcomes, growth, neurodevelopment and health-related quality of life (HRQoL) through 24 months of life in infants exposed to nipocalimab in pregnancies at high risk of early-onset severe haemolytic disease of the fetus and newborn (EOS-HDFN). Design A multicentre, open-label, single-arm trial. Setting Centres with expertise in HDFN management. Patients Pregnant individuals with previous EOS-HDFN and maternal anti-D titres ≥32 or anti-K titres ≥4. Interventions Weekly nipocalimab (30 and/or 45 mg/kg) from 14 to 35 gestational weeks. Main outcome measures Infants’ cord-blood alloantibody titres at birth, HDFN management, growth through 6 months, neurodevelopment (caregiver-reported Ages and Stages Questionnaire, third edition (ASQ-3)) and HRQoL assessments through 24 months of life. Results Of 13 pregnancies, 12 resulted in live births; one fetal loss occurred due to intrauterine transfusion (IUT) complications. A single simple transfusion was administered in one of seven infants delivered after a maternal nipocalimab course without IUTs, where cord blood alloantibody titres were <8. Multiple transfusions (one to seven simple transfusions/infant; one exchange transfusion) were administered to five infants delivered after early nipocalimab discontinuation and IUTs, with cord-blood alloantibody titres ranging from 512 to 32 768. No unusual growth patterns were observed through 6 months. No neurodevelopmental delays were identified through 24 months of life, with mean ASQ-3 domain scores within normal ranges. HRQoL outcomes were positive across physical, emotional, social and cognitive functioning. Conclusions Maternal nipocalimab in pregnancies at high risk of EOS-HDFN may reduce adverse neonatal outcomes correlating with low cord-blood alloantibody titres, without affecting growth through 6 months, neurodevelopment or HRQoL through 24 months of life. Trial registration number NCT03842189 .