The US Food and Drug Administration (FDA) has approved Sanofi’s Wayrilz (rilzabrutinib), marking it as the first BTK inhibitor authorized for treating persistent or chronic immune thrombocytopenia (ITP) in adults who failed to respond to prior therapies.
The treatment is expected to become available to US patients starting in September, with a list price of $17,500 per month, though actual costs will vary depending on insurance coverage.
Sanofi gained access to rilzabrutinib through its $3.7 billion acquisition of Principia Biopharma in 2020. Although the company’s initial focus had been on tolebrutinib (another BTK inhibitor), rilzabrutinib emerged as the first from that program to receive FDA approval. Sanofi termed Wayrilz a potential “multi-indication blockbuster,” projecting peak sales between €2 billion and €5 billion.
LUNA 3 Trial Results
The FDA’s decision was based on results from the pivotal Phase III LUNA 3 trial (NCT04562766), which demonstrated that Wayrilz achieved rapid and durable platelet responses, as well as improvements in ITP-related symptoms.
Patients receiving Wayrilz saw a statistically significant durable platelet response at week 25, with 23% achieving sustained improvement compared to none in the placebo group. Additionally, the median time to response was just 36 days, versus no measurable response in placebo patients.
Beyond platelet counts, patients reported a 10.6-point improvement across quality-of-life measures, compared to 2.3 points with placebo. The most common side effects observed were diarrhea, nausea, headache, abdominal pain, and COVID-19 infection.
“Immune thrombocytopenia management has traditionally focused on restoring platelet counts and reducing bleeding risk, but many patients still face persistent symptoms,” said Dr. David Kuter of Massachusetts General Hospital. “Wayrilz, through multi-immune modulation, provides a new treatment option, particularly for patients who fail steroids or other therapies.”
Wayrilz is an oral, reversible BTK inhibitor designed to address the root causes of ITP by modulating multiple immune pathways. Brian Foard, Sanofi’s Executive Vice President and Head of Specialty Care, noted that the therapy’s differentiated mechanism “aligns with Sanofi’s commitment to evolving therapeutic solutions for unmet patient needs.”
Immune thrombocytopenia is a rare autoimmune disorder characterized by the immune system’s destruction of platelets and suppressed platelet production. This leads to low platelet counts (often below 100,000 per µL), putting patients at heightened risk of bleeding, fatigue, bruising, and in severe cases, life-threatening events like intracranial hemorrhage.
What’s Next
Wayrilz operates by targeting Bruton’s tyrosine kinase (BTK), a protein critical across multiple immune pathways. Sanofi highlights its “multi-immune modulation” capability, meaning it addresses autoantibody production, Fcγ receptor-mediated immune activity, and inflammation simultaneously, rather than simply boosting platelet counts like conventional ITP therapies.
Wayrilz has already gained approval in the United Arab Emirates, with regulatory reviews ongoing in the European Union and China. Additionally, Sanofi’s HemAssist patient support program will assist US patients with access, insurance guidance, financial assistance, and educational resources.
On the regulatory front, rilzabrutinib has received Fast Track and Orphan Drug Designations for ITP from the FDA, and similar orphan status in Europe and Japan. Notably, the FDA also granted orphan drug designation for warm autoimmune hemolytic anemia (wAIHA) and IgG4-related disease in April 2025, underscoring Sanofi’s ambition to expand the drug’s indications. disease in April 2025, underscoring Sanofi’s ambition to expand the drug’s indications.
