Sanofi’s Wayrilz approved in Japan to treat immune thrombocytopenia

Sanofi's Wayrilz Gains Japanese Approval for Immune Thrombocytopenia

Sanofi's Wayrilz (rilzabrutinib), an oral reversible Bruton’s tyrosine kinase inhibitor, has received marketing and manufacturing authorization in Japan from the Ministry of Health, Labour and Welfare. This approval is for the treatment of persistent or chronic immune thrombocytopenia (ITP) in adult patients who have not responded sufficiently to other treatments. The decision is supported by positive results from the LUNA 3 Phase 3 study (NCT04562766), which demonstrated Wayrilz met its primary and secondary endpoints. Key findings included a statistically significant durable platelet response at week 25 (23% for Wayrilz vs. 0% for placebo; p<0.0001) and a faster time to first platelet response (36 days vs. not reached; p<0.0001). Patients also reported a 10.6-point improvement in overall quality of life.

• Japanese Regulatory Approval for ITP: Sanofi's Wayrilz (rilzabrutinib), an oral reversible BTK inhibitor, has been approved in Japan by the Ministry of Health, Labour and Welfare for persistent or chronic immune thrombocytopenia (ITP). This approval targets adult patients who have shown insufficient response to prior treatments or have tolerability issues, offering a new therapeutic option that addresses the underlying causes of ITP through multi-immune modulation.
• Positive Efficacy from LUNA 3 Study: The approval is underpinned by the LUNA 3 Phase 3 study (NCT04562766), which demonstrated Wayrilz's significant efficacy. The trial met its primary endpoint, showing a statistically significant durable platelet response at week 25, with 23% of Wayrilz-treated patients achieving this compared to 0% in the placebo arm (p<0.0001). Additionally, Wayrilz achieved a faster time to first platelet response, reaching it in 36 days versus not reached in the placebo arm (p<0.0001).
• Improved Quality of Life and Safety Profile: Beyond platelet counts, the LUNA 3 study also highlighted Wayrilz's positive impact on patient quality of life. Patients receiving Wayrilz reported an overall 10.6-point improvement in the quality of life domain, compared to a 2.3-point increase in the placebo arm, as measured by The Immune Thrombocytopenia Patient Assessment Questionnaire. The most common adverse reactions observed (incidence ≥10%) were diarrhea, nausea, headache, abdominal pain, and COVID-19, indicating a manageable safety profile.

Addressing Unmet Needs in Persistent ITP Treatment

Current treatment approaches for immune thrombocytopenia (ITP) are constrained by a lack of disease-specific therapies, significant variability in patient response, and an absence of validated predictive biomarkers to guide treatment selection. The therapeutic landscape remains largely empirical, with management heavily individualized based on patient comorbidities, prior treatment history, tolerability, and cost considerations.

• First-line corticosteroid limitations: High-dose corticosteroids remain the standard initial approach, yet only approximately 20% of patients achieve sustained remission. While roughly 33% of patients attain complete remission initially, the remainder experience platelet count decline upon dose reduction. Frequent side effects, heterogeneous responses, and high relapse rates collectively undermine the long-term utility of this approach — and managing bleeding symptoms without compounding steroid-related toxicity represents a persistent clinical challenge.

• Second-line therapy gaps: No consensus exists on the optimal second-line agent or the best sequence of treatments. Mycophenolate mofetil (MMF) demonstrates efficacy in 50–80% of patients with reasonable tolerability, but requires up to two months to take effect. Rituximab, despite initial response rates of up to 60%, yields durable remission in only 20–30% of patients on long-term follow-up, with no identified clinical or laboratory parameters reliably predictive of response — apart from a suggestion of higher response rates in younger women prior to the chronic phase.

• Absence of disease-modifying options: No treatment currently approved for ITP specifically halts autoantibody production or the accelerated platelet destruction central to its pathophysiology. Thrombopoietin receptor agonists (TPO-RAs) such as eltrombopag and romiplostim increase platelet production in a dose-dependent manner and reduce bleeding, but require continuous administration to maintain response and do not address the underlying immune dysregulation.

• Complexity of refractory disease management: Patients with relapsed or refractory ITP represent a particularly challenging population. Therapy is further complicated when contraindications exist to standard modalities — corticosteroids, splenectomy, or immunosuppressants — and all second-line options carry potential for adverse effects requiring ongoing monitoring. The COVID-19 pandemic has added urgency to the development of non-immunosuppressive treatment strategies.

• Systemic and economic burden: The cost of routine ITP treatment is high, and clinicians must navigate complex decisions around drug combinations, cumulative toxicities, and the risk of treatment dependence. Effective management also demands sustained patient–caregiver communication to align on disease impact, quality-of-life considerations, morbidity/mortality risk, and individualized therapeutic goals.

LUNA 3 Study: Efficacy and Safety of Wayrilz in ITP

The landscape of clinical trial design in immune thrombocytopenia (ITP) encompasses a range of study types — from randomized controlled trials and network meta-analyses to adaptive dose-finding studies and model-based in silico approaches. Endpoints span platelet response thresholds, time-to-event analyses, and patient-reported outcomes, reflecting the multidimensional burden of the disease. The following table summarizes key design parameters and endpoints across the major trials identified in the literature.

Wayrilz's Expanding Potential Beyond ITP

Rilzabrutinib's clinical development programme extends well beyond immune thrombocytopenia, reflecting the broad immunomodulatory potential of BTK inhibition across B cell- and mast cell-driven pathologies. As a reversible, covalent oral BTK inhibitor, rilzabrutinib targets multiple pathogenic immunological pathways — including B cell activation, autoantibody production, macrophage activity, and IgE/FcεRI-mediated signalling — making it mechanistically relevant across a range of immune-mediated disorders.

• Warm autoimmune haemolytic anaemia (wAIHA): Rilzabrutinib is under investigation as a B cell/plasma cell-targeting agent in wAIHA, leveraging its ability to suppress autoantibody-producing B cell populations via BTK inhibition.

• Pemphigus vulgaris: A multicentre, proof-of-concept Phase II trial evaluated oral rilzabrutinib (400–600 mg twice daily) over 12 weeks in patients with Pemphigus Disease Area Index severity scores of 8–45, followed by a 12-week follow-up period. Of 27 patients enrolled (33% newly diagnosed, 67% relapsing), the primary endpoint of disease activity control within 4 weeks on zero-to-low-dose corticosteroid was achieved in 52% of patients (95% CI: 32–71%). Complete response by week 24 was achieved in 22% of patients, with treatment-related adverse events predominantly grade 1–2.

• IgG4-related disease: Rilzabrutinib is being explored in this fibroinflammatory condition, where B cell-driven plasmablast activity and IgG4 autoantibody production represent key therapeutic targets amenable to BTK inhibition.

• Chronic spontaneous urticaria (CSU) and asthma: Rilzabrutinib is among the BTK inhibitors showing the most promise in allergic and mast cell-driven diseases. Current evidence supports a role for BTK in CSU, chronic inducible urticaria, and asthma, particularly where FcεRI/IgE-mediated pathogenesis predominates, though the role of BTK in asthma remains to be fully defined and warrants further clinical investigation.

• Sickle cell disease: Rilzabrutinib is also being developed in sickle cell disease, an indication that likely exploits the anti-inflammatory and immunomodulatory properties of BTK inhibition beyond classical autoimmune pathways.

Note: Specific intervention models (e.g., single-arm, randomised controlled) for the wAIHA, IgG4-related disease, asthma, CSU, and sickle cell disease trials are not detailed in the available literature at this time.

Wayrilz Approval: A New Horizon for BTK Inhibitors in ITP

The recent marketing authorization of Sanofi's Wayrilz (rilzabrutinib) in Japan for persistent or chronic immune thrombocytopenia (ITP) marks a pivotal moment for patients grappling with this challenging autoimmune disorder. For adults who have not responded sufficiently to other treatments, this oral, reversible Bruton's tyrosine kinase (BTK) inhibitor offers a much-needed alternative. The LUNA 3 Phase 3 study provided compelling evidence, demonstrating a statistically significant durable platelet response in 23% of patients compared to none on placebo, alongside a rapid median time to first response of just 15 days. Beyond simply raising platelet counts, Wayrilz also significantly improved patient quality of life, notably reducing physical fatigue and bleeding scores, which are critical aspects of ITP management often overlooked by other therapies.

This approval strategically positions Wayrilz as a valuable addition to the ITP therapeutic armamentarium, expanding the utility of BTK inhibitors beyond their established role in B-cell malignancies. Its unique dual mechanism of action, which includes decreasing macrophage-mediated platelet destruction and reducing pathogenic autoantibody production while preserving platelet aggregation, differentiates it from other BTK inhibitors and existing ITP treatments. However, the competitive landscape remains a key consideration; without direct comparative data against established therapies like TPO-RAs or rituximab, its precise positioning and market penetration will require careful strategic execution. Furthermore, clinicians will need to be mindful of potential drug-drug interactions, a common characteristic of BTK inhibitors, to ensure optimal patient safety and efficacy. While the safety profile observed in trials was generally favorable, with mostly mild-to-moderate adverse events, ongoing long-term surveillance will be essential to fully understand its safety in a broader patient population, especially given the class-wide concerns seen with other BTK inhibitors. This development underscores the potential for targeted immune modulation to redefine care in autoimmune diseases, with future studies likely exploring earlier intervention and broader applications for rilzabrutinib.