Topline Findings
- FDA Approval Milestone: Wayrilz receives FDA approval as the first Bruton’s tyrosine kinase inhibitor for adults with persistent or chronic immune thrombocytopenia (ITP) who have not responded to prior therapy.
- Clinical Efficacy and Safety: Phase III LUNA 3 trial shows durable platelet response, faster time to response, improved quality of life, and a manageable safety profile for Wayrilz compared to placebo.
- Multi-Immune Modulation Therapy: Wayrilz’s novel mechanism targets multiple immune pathways, offering a new treatment option for ITP patients who fail steroids or existing therapies.
The FDA has approved Sanofi’s Wayrilz (rilzabrutinib) as the first Bruton’s tyrosine kinase (BTK) inhibitor indicated for adults with persistent or chronic immune thrombocytopenia (ITP) who have not responded adequately to prior therapy. According to the company, approval was based on results from the Phase III LUNA 3 trial (NCT04562766), which demonstrated significant and durable improvements in platelet counts, faster time to response, and enhanced patient-reported quality of life versus placebo.1
How does Wayrilz Address the Underlying Mechanisms of Immune Thrombocytopenia?
“The burden of immune thrombocytopenia can be both physical and emotional with significant overlooked symptoms that can impact various aspects of daily living,” said Caroline Kruse, president, CEO, Platelet Disorder Support Association, in a press release. “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."
LUNA 3 Trial Design and Treatment Regimen
- The randomized, multicenter, double-blind LUNA 3 trial evaluated the safety and efficacy of Wayrilz in 232 patients with persistent or chronic ITP.
- Patients were given either oral Wayrilz 400 mg twice daily or a placebo during a double-blind treatment phase lasting 12 to 24 weeks.
- This was followed by a 28-week open-label phase and then either a four-week safety follow-up or entry into a long-term extension phase.
Endpoints and Efficacy Results
- The primary endpoint of the trial was durable platelet response, defined as the proportion of participants able to achieve platelet counts at or above 50,000/μL for more than two-thirds of at least eight non-missing weekly scheduled platelet measurements during the last 12 weeks of the 24-week blinded treatment period in the absence of rescue therapy.
- Key secondary endpoints included time to platelet response, number of weeks maintaining a specific platelet response, rescue therapy use, physical fatigue score, and bleeding score.1,2
- Results showed that at week 25, 23% of patients treated with Wayrilz achieved a durable platelet response compared to none in the placebo group.
- Patients treated with Wayrilz also demonstrated a median time to first platelet response of 36 days, which was not reached in the placebo group.
- The median duration of response for patients treated with Wayrilz was seven weeks compared to one week in the placebo group.
- Patients in the treatment group also reported meaningful improvements in quality of life, with a 10.6-point increase across nine symptom measures versus a 2.3-point improvement for placebo.
- Common adverse events included diarrhea, nausea, headache, abdominal pain, and COVID-19.1
Sanofi’s Perspective and Mechanism of Action
“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,” said Brian Foard, EVP, head, specialty care, Sanofi, in the press release. “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."
Epidemiology and Patient Population
- In the United States, the incidence of adult ITP is estimated to be 3.3 per every 100,000 people annually.
- Forty percent of individuals diagnosed with ITP are children aged 10 years or younger.
- ITP is most common in people over 60 years of age.3
Clinical Expert Perspective
“Traditionally, immune thrombocytopenia 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 author David Kuter, MD, director, clinical Hematology at Massachusetts General Hospital and professor of Medicine at Harvard Medical School, said in the press release. “Through multi-immune modulation, Wayrilz can offer a new option for patients, including those who fail steroids or do not respond to existing treatment.”
References
- Press Release: Sanofi’s Wayrilz approved in US as first BTK inhibitor for immune thrombocytopenia. Sanofi. August 29, 2025. Accessed September 2, 2025. https://www.sanofi.com/en/media-room/press-releases/2025/2025-08-29-21-50-18-3141825
- Study to Evaluate Rilzabrutinib in Adults and Adolescents With Persistent or Chronic Immune Thrombocytopenia (ITP) (LUNA 3). Clinicaltrials.gov. Accessed September 2, 2025. https://clinicaltrials.gov/study/NCT04562766?term=NCT04562766&rank=1
- Immune Thrombocytopenia. NORD. Accessed September 2, 2025. https://rarediseases.org/rare-diseases/immune-thrombocytopenia/#affected
