The New England Journal of MedicineNipocalimab in Early-Onset Severe Hemolytic Disease of the Fetus and Newborn

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A phase 2 study evaluated the efficacy of nipocalimab, an anti-neonatal Fc receptor blocker, in treating early-onset severe hemolytic disease of the fetus and newborn (HDFN). The research focused on pregnancies at high risk for recurrent early-onset severe HDFN, assessing the ability of nipocalimab to delay or prevent fetal anemia and intrauterine transfusions.

Study Design:

• International, open-label, single-group, phase 2 study
• Participants: Pregnancies at high risk for recurrent early-onset severe HDFN
• Treatment: Intravenous nipocalimab (30 or 45 mg/kg/week) from 14 to 35 weeks’ gestation
• Primary endpoint: Live birth at ≥32 weeks’ gestation without intrauterine transfusions
• Historical benchmark: 0% (clinically meaningful difference: 10%)

Key Findings:

• 54% (7/13) of pregnancies resulted in live birth at ≥32 weeks without intrauterine transfusions
• No cases of fetal hydrops occurred
• 46% (6/13) of participants did not require antenatal or neonatal transfusions
• 6 fetuses received intrauterine transfusions (5 at ≥24 weeks, 1 before fetal loss at 22 weeks 5 days)
• 12 live births with a median gestational age of 36 weeks 4 days
• Of 12 live-born infants: 1 received exchange and simple transfusion, 5 received only simple transfusions
• Treatment reduced maternal alloantibody titer and IgG levels in maternal samples and cord blood
• No unusual maternal or pediatric infections observed
• Serious adverse events were consistent with HDFN, pregnancy, or prematurity

HCN Medical Memo
Althese these results are encouraging, larger studies are needed to confirm the efficacy and safety of nipocalimab in treating early-onset severe HDFN. Clinicians should monitor ongoing research in this area, as it may lead to new management strategies for alloimmune conditions during pregnancy.

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