SNY's Rilzabrutinib Wins 4th Orphan Drug Tag for Sickle Cell Disease

Core Insights - Sanofi's investigational BTK inhibitor, rilzabrutinib, has received orphan drug designation from the FDA for sickle cell disease (SCD), marking its fourth such indication [1][2][6] - Rilzabrutinib aims to reduce vaso-occlusive crises by modulating immune responses and has shown promising results in preclinical studies [1][3] - SCD affects over 100,000 individuals in the U.S., leading to severe complications and a significantly reduced life expectancy [4] Company Developments - Rilzabrutinib is currently under FDA review for immune thrombocytopenia (ITP), with a decision expected by August 29, 2025 [6][10] - The drug has also received orphan drug designation for treating warm autoimmune hemolytic anemia (wAIHA) and IgG4-related disease (IgG4-RD), both of which have significant unmet medical needs [7][9] - Sanofi's acquisition of Principia Biopharma included rilzabrutinib, which is also being developed for other immune-mediated diseases [11] Clinical Data - Preclinical studies indicate that rilzabrutinib effectively reduced vaso-occlusion and inflammation in SCD mouse models [3][6] - Phase IIb studies for wAIHA have shown clinically meaningful outcomes, while phase IIa studies for IgG4-RD demonstrated reductions in disease flare and other markers [8]