Sanofi SNY announced that the European Medicines Agency (EMA) has granted orphan drug designation to its investigational BTK inhibitor, rilzabrutinib, for treating IgG4-related disease (IgG4-RD).
IgG4-RD is a chronic, immune-mediated rare condition that can affect multiple organs, causing inflammation, swelling and fibrosis.
The EMA grants this designation to support the development of medicines for rare disorders that affect not more than 5 in 10,000 patients in the EU.
Rilzabrutinib is currently being evaluated in a phase II study for IgG4-RD. Data from the same showed that treatment with rilzabrutinib for 52 weeks led to a reduction in disease flare, other disease markers and glucocorticoid sparing in the given patient population.
The FDA recently granted an orphan drug designation to rilzabrutinib for treating IgG4-RD.
Besides IgG4-RD, rilzabrutinib is also being developed for treating several other rare diseases in the United States, the EU and other countries.
SNY's Rilzabrutinib Under Review in the U.S. for ITP
Sanofi has developed rilzabrutinib for treating immune thrombocytopenia (ITP), a rare autoimmune disorder. The candidate already enjoys orphan drug designation for the ITP indication in the United States, the EU and Japan.
A regulatory application seeking approval for rilzabrutinib for treating ITP is currently under review in the United States. A final decision from the FDA is expected on Aug. 29, 2025. The regulatory body previously granted a fast-track designation to rilzabrutinib for treating ITP in the United States.
Besides the United States, rilzabrutinib is also under review in the EU and China as a potential treatment for ITP.
The FDA had previously granted orphan drug designation to rilzabrutinib for warm autoimmune hemolytic anemia (wAIHA) and sickle cell disease (SCD). The candidate is being developed in a mid-stage study for treating wAIHA, while it is yet to enter clinical development for SCD.
Rilzabrutinib was added to Sanofi’s pipeline with the acquisition of Principia Biopharma. The candidate is also being developed in mid-stage studies for other immune-mediated diseases like asthma and chronic spontaneous urticaria.
SNY's Competition in the Target Market
Upon potential approval, rilzabrutinib will likely face competition from existing approved therapies in the target market.
Rigel Pharmaceuticals RIGL currently markets Tavalisse (fostamatinib) for the treatment of thrombocytopenia in adult patients with chronic ITP who have had an insufficient response to a previous treatment.
In the first six months of 2025, RIGL recorded $68.5 million in Tavalisse sales, up 44% on a year-over-year basis.
Meanwhile, the FDA approved Amgen’s AMGN Uplizna (inebilizumab) for treating adults with IgG4-RD in April 2025. Following the nod, Uplizna became the first and only drug approved by the FDA for the treatment of IgG4-RD.
Uplizna was added to Amgen’s portfolio following the acquisition of Horizon Therapeutics in 2023. Uplizna is also approved in the United States for treating adults with a rare autoimmune disease called neuromyelitis optica spectrum disorder.
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Sanofi (SNY): Free Stock Analysis Report Amgen Inc. (AMGN): Free Stock Analysis Report Rigel Pharmaceuticals, Inc. (RIGL): Free Stock Analysis ReportThis article originally published on Zacks Investment Research (zacks.com).
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