Sanofi's Wayrilz wins Japan approval for immune thrombocytopenia
Sanofi has secured marketing authorisation in Japan for Wayrilz (rilzabrutinib), an oral reversible Bruton's tyrosine kinase inhibitor (BTKi), for the treatment of persistent or chronic immune thrombocytopenia (ITP) in adults who have not responded adequately to existing therapies or for whom tolerability is a concern. The Ministry of Health, Labour and Welfare granted the authorisation on 23 June 2026, adding Japan to a list of approved markets that now includes the US, EU, UK, and UAE.
ITP is a rare autoimmune condition characterised by abnormally low platelet counts, which can cause bruising, bleeding episodes, and in severe cases life-threatening intracranial haemorrhage. Beyond the haematological picture, patients frequently report fatigue and cognitive difficulties, creating a burden that extends well beyond platelet metrics.
Trial data
The Japan approval rests on the LUNA 3 Phase 3 study (NCT04562766), which enrolled 202 adults with persistent or chronic ITP in a double-blind, placebo-controlled design. At week 25, 23% of patients in the Wayrilz arm achieved a durable platelet response, compared with none in the placebo arm (p less than 0.0001). Wayrilz-treated patients also reached a first platelet response in a median of 36 days, while the placebo arm did not reach a median response at all. Patients treated with the drug reported an average 10.6-point improvement in overall quality of life on the ITP Patient Assessment Questionnaire, against a 2.3-point gain for placebo, though this analysis was descriptive and not powered for statistical significance.
The most commonly reported adverse reactions, occurring in at least 10% of participants, were diarrhoea, nausea, headache, abdominal pain, and COVID-19.
Hisashi Kato, MD, PhD, of the Department of Blood Transfusion and Cell Therapy at the University of Osaka Hospital, said Wayrilz "is expected to become a new therapeutic option that may help patients with disease management, including not only improvement in platelet counts but also considering patients' quality of life."
Market context and competitive landscape
The ITP treatment landscape has become considerably more active over the past decade. Thrombopoietin receptor agonists such as romiplostim and eltrombopag are well-established second-line options, and the anti-CD20 agent rituximab is used off-label in refractory cases. More recently, the FcRn inhibitor class, represented by drugs such as efgartigimod alfa and rozanolixizumab, has entered the ITP space with a distinct mechanism targeting immunoglobulin G recycling. Wayrilz differentiates itself by targeting BTK, which is expressed in B cells, macrophages, and other innate immune cells, giving it the multi-immune modulation profile Sanofi emphasises in its positioning.
Japan has granted Wayrilz orphan drug designation not only for ITP but also for IgG4-related disease and warm autoimmune haemolytic anaemia, both of which remain under active clinical investigation. Sanofi is also studying the compound in sickle cell disease. The breadth of these programmes suggests the company views rilzabrutinib as a platform asset across rare immune-mediated conditions rather than a single-indication product.
For Sanofi, the Japan milestone consolidates a global ITP franchise at a time when the company is sharpening its focus on immunology and rare disease, areas it has publicly identified as strategic growth priorities. Investors and analysts will be tracking uptake curves across the five approved markets, and watching for additional readouts from the non-ITP programmes as the next set of meaningful catalysts.