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Foetal neonatal alloimmune thrombocytopenia (FNAIT): Fast track designation for investigational therapy to reduce the risk in alloimmunised pregnant adults

FNAIT is a rare and severe condition that occurs when the immune system of a pregnant person mistakenly attacks platelets in a developing foetus. This immune response can lead to impaired clotting ability and bleeding, posing a significant risk to the foetus or newborn.1

On 26 March 2024, the US Food and Drug Administration (FDA) granted Fast Track designation (FTD) for nipocalimab to reduce the risk of FNAIT in alloimmunised pregnant adults during their current pregnancy.

Nipocalimab is the only investigational therapy currently reported to be in clinical development to address the needs of alloimmunised pregnant individuals at risk of FNAIT. It was granted orphan drug designation by the US FDA for FNAIT in December 2023.

“Receiving Fast Track designation for nipocalimab in FNAIT underscores the urgency to address the unmet need for safe, effective, and targeted treatments to prevent FNAIT, a condition that could carry severe health consequences and even be fatal for the foetus or newborn.”

Katie Abouzahr, MD, vice president, autoantibody and maternal foetal immunology disease area leader, Johnson & Johnson .

Nipocalimab, an FcRn blocker, is believed to work by blocking the transfer of immunoglobulin G (IgG) alloantibodies from pregnant individuals to their babies through the placenta while not suppressing the broader immune systems of the pregnant individual or developing foetus.2 

Johnson & Johnson is also proceeding with two Phase 3 trials focused on FNAIT.

Nipocalimab is additionally being studied in haemolytic disease of the foetus and newborn (HDFN), another alloimmune disease of pregnancy with a similar disease mechanism, often referred to as the red blood cell counterpart to FNAIT.3 After phase 2 safety and efficacy results from the UNITY trial, Johnson & Johnson is additionally proceeding withphase 3 trialsfocused on HDFN.4


1 NORD. Foetal and Neonatal Alloimmune Thrombocytopenia. Published online July 2022. Accessed August 2023.

2 Ling LE, Hillson JL, Tiessen RG, et al. M281, an anti-FcRn antibody: pharmacodynamics, pharmacokinetics, and safety across the full range of IgG reduction in a first-in-human study. Clin Pharmacol Ther. 2019;105(4):1031-1039.

3 Orphanet. Foetal and Neonatal Alloimmune Thrombocytopenia. Accessed on February 28, 2024. 

4 A Study to Evaluate the Safety, Efficacy, Pharmacokinetics and Pharmacodynamics of M281 Administered to Pregnant Women at High Risk for Early Onset Severe Hemolytic Disease of the Foetus and Newborn (HDFN). Accessed: November 18, 2022.

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