The European Medicines Agency (EMA) has granted orphan drug designation to rilzabrutinib, Sanofi’s investigational Bruton’s tyrosine kinase (BTK) inhibitor, for the treatment of IgG4-related disease (IgG4-RD). This designation is awarded to therapies that address rare, life-threatening, or seriously debilitating conditions affecting no more than 5 in 10,000 people in the European Union.
Promising Results from Phase 2 Clinical Trial
Rilzabrutinib’s orphan drug status follows promising results from a Phase 2 clinical trial (NCT04520451), which were presented at the EULAR 2025 Congress. In patients with IgG4-RD, 52 weeks of treatment with rilzabrutinib led to a reduction in disease flare-ups, decreased use of glucocorticoids, and improvement in other disease markers. The study also confirmed that the drug’s safety profile was consistent with earlier trials, showing no new safety concerns.
Global Expansion of Rilzabrutinib’s Orphan Designation
Beyond the EU, rilzabrutinib has already received orphan drug designation in the United States and Japan for several autoimmune and rare conditions. These include immune thrombocytopenia (ITP), warm autoimmune hemolytic anemia, IgG4-related disease, and sickle cell disease. The drug has also been granted Fast Track designation by the U.S. FDA for ITP and IgG4-RD.
Regulatory Review Underway
Rilzabrutinib is currently under regulatory review in the U.S., EU, and China for its potential use in ITP. The FDA’s target action date is August 29, 2025. As rilzabrutinib is still an investigational agent, its safety and efficacy have not yet been approved by any regulatory authority.
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