Sanofi’s Wayrilz becomes first FDA-approved BTK drug for a rare bleeding disorder

The FDA approved Sanofi’s Wayrilz (rilzabrutinib) for adults with chronic or persistent immune thrombocytopenia (ITP) who haven’t responded to previous treatments, making it the first Bruton tyrosine kinase (BTK) inhibitor cleared for ITP in the U.S.

Why it matters: This approval gives hope to 25,000 U.S. patients struggling with a difficult-to-treat, unpredictable autoimmune disorder. Wayrilz’s unique mechanism addresses the root causes of ITP, not just the symptoms, offering a potential new standard in treatment.

Backstory: Sanofi originally acquired rilzabrutinib in its $3.7B purchase of Principia Biopharma in 2020, aiming for another BTK drug, tolebrutinib, as the main prize. After disappointing results for tolebrutinib in multiple sclerosis, Sanofi pivoted its focus to rilzabrutinib.

Zoom in: The phase 3 LUNA 3 trial showed that, after 36 days, 23% of patients taking Wayrilz experienced sustained platelet increase vs 0% of patients that took the placebo. Not only this, but patients reported reduced fatigue and bleeding severity while Wayrilz had a similar safety profile to the placebo.

Big picture: Sanofi projects peak sales of €2–5B for the drug, which is also being studied in asthma, chronic hives, autoimmune anemia, and other rare diseases. Global regulatory reviews are underway in the EU and China.