The U.S. Food and Drug Administration (FDA) has granted orphan drug designation to rilzabrutinib, an innovative oral therapy designed to address vaso-occlusive crises (VOCs) in individuals with sickle cell disease (SCD). Rilzabrutinib is a reversible Bruton's tyrosine kinase (BTK) inhibitor that functions through multi-immune modulation, aiming to reduce VOCs by targeting inflammatory pathways involved in the disease.
The FDA’s orphan drug designation is awarded to investigational treatments for rare conditions affecting fewer than 200,000 people in the U.S., providing development incentives such as market exclusivity and tax credits.
Dr. Karin Knobe, Global Head of Development, Rare Diseases, emphasized the significance of this milestone:
“Securing our fourth orphan drug designation for rilzabrutinib highlights our commitment to meeting the urgent medical needs of patients living with rare diseases. Individuals with sickle cell disease often suffer from painful and potentially life-threatening vaso-occlusive episodes that drastically reduce quality of life and longevity. There is a clear need for new therapeutic strategies that can modulate immune system responses contributing to SCD complications.”
Beyond sickle cell disease, rilzabrutinib has also received orphan drug designation in multiple regions for other rare autoimmune disorders:
Immune thrombocytopenia (ITP) – in the U.S., EU, and Japan
Warm autoimmune hemolytic anemia (wAIHA) – in the U.S. and EU
IgG4-related disease (IgG4-RD) – in the U.S.
Although rilzabrutinib is still under investigation and not yet approved by regulatory authorities, its safety and efficacy are being evaluated. Currently, the drug is under regulatory review in the U.S., European Union, and China for its potential application in ITP. The FDA has granted it fast track designation, and a decision on approval for ITP is expected by August 29, 2025.
This latest designation reinforces the growing interest in BTK inhibitors as potential game-changers in the treatment of complex immune-mediated and hematologic conditions.