J&J's Nipocalimab for FNAIT Gets on Fast Track for Approval

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FDA granted fast track designation to nipocalimab, which J&J is developing for helping alloimmunized pregnant adults treat FNAIT, a rare disease that poses risk to the fetus or newborn.

Editors' note: this story was originally published on BioPharmInternational.com.

FDA granted Johnson & Johnson (J&J) fast track designation on March 26, 2024 for nipocalimab to reduce the risk of fetal neonatal alloimmune thrombocytopenia (FNAIT) in alloimmunizeda pregnant adults during a current pregnancy. Nipocalimab is a high-affinity, fully human, aglycosylated, effectorless, monoclonal antibody (mAb), which, according to AstraZeneca in a company press release, is the only investigational therapy in clinical development to address this indication. Nipocalimab was earlier granted orphan drug designation by FDA for the FNAIT indication in December 2023.

The mAb aims to selectively block the neonatal crystallizable fragment receptor (FcRn), and in doing so, reduce the levels of circulating immunoglobulin G (IgG) antibodies, including autoantibodies and alloantibodies that underlie multiple conditions, J&J stated in its press release. According to the company, “Nipocalimab is the only FcRn blocker being studied across three key segments in the autoantibody space: rare autoantibody diseases (e.g., generalized myasthenia gravis in adults and children, chronic inflammatory demyelinating polyneuropathy, warm autoimmune hemolytic anemia, and idiopathic inflammatory myopathies); maternal fetal diseases mediated by maternal alloantibodies (e.g., hemolytic disease of the fetus and newborn and fetal and neonatal alloimmune thrombocytopenia); and prevalent rheumatology (e.g., rheumatoid arthritis, Sjögren’s disease, and systemic lupus erythematosus).”

FNAIT is a severe and rare condition. It occurs when the pregnant person’s immune system mistakenly attacks a developing fetus’ platelets, which can impair clotting ability and lead to internal bleeding, which poses a significant risk to the fetus or newborn. Blocking FcRn can potentially reduce overall IgG levels, including pathogenic alloantibody levels. At the same time, the blockage can preserve immune function without causing immunosuppression on a broader scale. Blocking IgG from binding to FcRn in the placenta may also potentially prevent the transfer of maternal alloantibodies to the fetus, according to the press release.

“Receiving [f]ast [t]rack 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 fetus or newborn,” said Katie Abouzahr, vice-president, Autoantibody and Maternal Fetal Immunology Disease Area Leader, Johnson & Johnson, in the release. “We are committed to applying our decades of immunology leadership to pioneer innovative approaches to transform treatment for patients and their families affected by FNAIT and other alloantibody-driven diseases of pregnancy.”

Nipocalimab is also being studied for treating hemolytic disease of fetus and newborn (HDFN), another alloimmune disease related to pregnancy. HDFN has a similar disease mechanism as FNAIT and is often referred to as the red-blood-cell-counterpart to FNAIT. J&J will proceed with Phase III trials focused on HDFN following safety and efficacy results from a Phase II trial.


The rare disease sector is currently a major focus of big biopharmaceutical companies. For instance, earlier this year in January 2024, Sanofi made a move to acquire Inhibrx, a clinical-stage biopharmaceutical company. The deal is valued at approximately $1.7 billion (1). Among the assets Sanofi will gain is INBRX-101, a human recombinant protein that can potentially normalize serum alpha-1-antitrypsin (AAT) levels in patients that are AAT deficient. AAT deficiency is a rare genetic disease that is defined by low levels of AAT protein. Symptoms primarily affect the lungs, and there is a progressive deterioration of the tissue.

In addition, AstraZeneca recently received FDA approval for its rare-disease therapeutic, Ultomiris (ravulizumab-cwvz). FDA approved Ultomiris on March 25, 2024 for treating adult patients with anti-aquaporin-4 (AQP4) antibody-positive (Ab+) neuromyelitis optica spectrum disorder (NMOSD) in the United States (2). NMOSD is a rare and debilitating autoimmune disease that affects the central nervous system, including the spine and optic nerves.


1. Sanofi. Sanofi to Acquire Inhibrx, Inc., Adding Potential Best-In-Class Rare Disease Asset for Alpha-1 Antitrypsin Deficiency to Pipeline. Press Release, Jan. 23, 2024.
2. AstraZeneca. Ultomiris Approved in the US for the Treatment of Adults with Neuromyelitis Optica Spectrum Disorder (NMOSD). Press Release, March 25, 2024.

Source: Johnson & Johnson