A global Phase 3 study is ongoing to determine whether nipocalimab can reduce the risk of severe complications from fetal and neonatal alloimmune thrombocytopenia (FNAIT).
What is FNAITFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth.?
Fetal and neonatal alloimmune thrombocytopeniaFetal and neonatal alloimmune thrombocytopenia A rare condition in which a mother’s immune system attacks fetal platelets, leading to dangerously low platelet levels before and/or after birth. (FNAIT) is a rare but serious condition in which a pregnant mother’s immune system produces antibodies against the platelets of her fetus. This occurs when a fetus inherits platelet antigens from the father that are not compatible with the mother, typically involving a protein called human platelet antigenHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT. (HPAHuman platelet antigen Proteins found on the surface of platelets. Incompatibility between maternal and fetal human platelet antigens can trigger FNAIT.). The mother’s immune system recognizes the fetal platelets as foreign, attacking and destroying them, leading to low platelet levels (thrombocytopeniaThrombocytopenia A platelet count that is lower than normal.) in the fetus or newborn.
The FREESIA-1 trial is designed to find out if nipocalimab works better than placebo in preventing the most serious outcomes. These include fetal or neonatal death, severe bleeding and very low platelet counts, defined as less than 30×109/L, during the first week after birth. For patients and families, this research aims to answer whether a targeted therapy can meaningfully lower the risk of life-threatening complications in pregnancies already known to be at high risk.
The study, sponsored by Janssen Research and Development, began in November 2024 and is expected to complete in December 2029. It plans to enroll 39 pregnant participants across 21 sites in Europe, Israel and South America. Participants are randomly assigned to receive either intravenous nipocalimab or a placebo, and both patients and investigators are blinded to the assignment.
Eligible participants are women aged 18 to 45 years who are between 13 and 18 weeks pregnant and have a prior pregnancy affected by FNAIT, without a history of severe bleeding in that pregnancy. They must also have confirmed antibodies against human platelet antigen 1a and a fetus positive for that antigen. Women with multiple gestations, a history of severe preeclampsia or certain cardiovascular conditions are excluded.
Read more about therapies for FNAIT
Researchers will track several outcomes, including bleeding events, platelet counts at birth and whether newborns need platelet transfusions or intravenous immunoglobulinIntravenous immunoglobulin A treatment given to pregnant women with a history of FNAIT or known alloantibodies. IVIG reduces the immune reaction against fetal platelets.. Safety is also a major focus. Investigators will monitor treatment-emergent adverse events in both mothers and infants through up to 24 weeks postpartum for mothers and up to 104 weeks for infants, including infections, clotting events and developmental progress.
If successful, nipocalimab could change how high-risk FNAIT pregnancies are managed. Current approaches often involve intensive monitoring and repeated treatments. A therapy that directly reduces the underlying immune attack could simplify care and improve outcomes. For patients, that may mean fewer interventions, lower stress during pregnancy and a better chance of delivering a healthy baby.
Sign up here to get the latest news, perspectives, and information about FNAIT sent directly to your inbox. Registration is free and only takes a minute.
