FDA Approves BTK Inhibitor Rilzabrutinib for Immune Thrombocytopenia

The United States Food and Drug Administration (US FDA) has approved rilzabrutinib under the name Wayrilz for adults with persistent or chronic immune thrombocytopenia (ITP) who have had an insufficient response to a previous treatment as of August 29.1

“Traditionally, ITP management has focused on restoring platelet counts and reducing bleeding risk, which for some patients may result in suboptimal responses, persistent symptoms, or unacceptable treatment complications,” study investigator David Kuter, MD, Director of Clinical Hematology at Massachusetts General Hospital and Professor of Medicine at Harvard Medical School, said in a statement.1 “Through multi-immune modulation, Wayrilz can offer a new option for patients, including those who fail steroids or do not respond to existing treatment.”

Rilzabrutinib is a novel oral, reversible, Bruton’s tyrosine kinase (BTK) inhibitor. The FDA approved the therapy based off data from the pivotal LUNA 3 phase 3 study, which met the primary and secondary endpoints, significantly and consistently increasing platelet counts and showing positive impacts on other ITP symptoms. The trial included adult patients with persistent or chronic ITP and severely low platelet counts (median of 15,000/μL) receiving oral rilzabrutinib 400 mg twice a day (n = 133) or placebo (n = 69) for up to 24 weeks followed by 28 weeks of open-label period.2

Investigators found that platelet response was achieved in 65% (n = 86) of patients receiving rilzabrutinib compared to 33% (n = 23) of patients on placebo. Rilzabrutinib demonstrated durable platelet response in 23% of ITP adult patients compared to 0% in the placebo arm (P <.0001). Participants receiving rilzabrutinib experienced reduced bleeding, an improved number of weeks with platelet response, a reduced need for rescue therapy use, and improved physical fatigue and quality of life measures.2

“The burden of immune thrombocytopenia can be both physical and emotional with significant overlooked symptoms that can impact various aspects of daily living,” Caroline Kruse, President and CEO at the Platelet Disorder Support Association, added.1 “We are pleased to have a new treatment option that can help ease the ongoing strain of managing the disease for patients and their families."

Significant improvements with rilzabrutinib vs placebo were seen in bleeding scores (mean change [SE] at week 25: –0.04 [0.02] vs 0.05 [0.02]; P = .0006). Patients on rilzabrutinib were about three times more likely to achieve a platelet response (HR, 3.1; 95% CI, 1.9–4.9; P <.0001), with a median time to first response of 36 days vs not reached for placebo; among responders, median time to response was 15 days. Rilzabrutinib also reduced the need for rescue therapy by 52% (P = .0007). Clinically meaningful improvements in physical fatigue were observed at week 13 (LS mean change 8.0 vs –0.1; LS mean difference 8.1; P = .01), sustained through week 25, and noted even in non-durable platelet responders, along with better outcomes across other quality-of-life domains.2

“With its differentiated mechanism of action, Wayrilz has the potential to become a treatment of choice for immune thrombocytopenia patients who have not responded to a prior therapy,” Brian Foard, Executive Vice President, Head of Specialty Care at Sanofi, added.1 “Its multi-immune modulation approach shows promise in addressing the key drivers of immune thrombocytopenia, which aligns with Sanofi's commitment to adapting and evolving therapeutic solutions to help tackle ongoing unmet patient needs. This approval underscores Sanofi's expertise and ambitions at the junction of rare and immunological disease."

References

1. Press Release: Sanofi’s Wayrilz approved in US as first BTK inhibitor for immune thrombocytopenia. News release. Sanofi. August 29, 2025. https://www.sanofi.com/en/media-room/press-releases/2025/2025-08-29-21-50-18-3141825

2. Arnold D. Effect of rilzabrutinib on platelet count variability in previously treated ITP: LUNA3 phase 3 data. Poster presented at the 2025 International Society on Thrombosis and Haemostasis Congress in Washington, D.C., June 21-25, 2025.