Breaking Barriers: Rilzabrutinib Gains FDA Orphan Drug Status for Two Rare Diseases

The U.S. Food and Drug Administration (FDA) has recognized rilzabrutinib, an investigational oral Bruton’s tyrosine kinase (BTK) inhibitor, as an orphan drug for two rare and challenging conditions: warm autoimmune hemolytic anemia (wAIHA) and IgG4-related disease (IgG4-RD). This milestone highlights the urgent need for new treatment options in these immune-mediated diseases, as no approved therapies currently exist. Orphan drug designation provides crucial incentives, such as tax credits and market exclusivity, to encourage the development of treatments for conditions affecting fewer than 200,000 people in the U.S.

Karin Knobe, MD, PhD, Global Head of Development for Rare Diseases, emphasized the company’s commitment to advancing therapies for small but underserved patient populations. Rilzabrutinib is already under regulatory review in the U.S., EU, and China for immune thrombocytopenia (ITP), with an FDA decision expected by August 29, 2025. The drug’s multi-immune modulation potential is now being explored across multiple conditions, reinforcing hopes for innovative solutions in rare disease care.