FDA Grants Orphan Drug Status to Sanofi’s Rilzabrutinib: A New Hope for wAIHA, IgG4-RD, and Beyond

(IN BRIEF) Rilzabrutinib, an investigational oral BTK inhibitor, has received orphan drug designation from the FDA for treating warm autoimmune hemolytic anemia (wAIHA) and IgG4-related disease (IgG4-RD), two rare conditions with no approved treatments. This designation, aimed at addressing unmet medical needs for conditions affecting fewer than 200,000 people in the US, complements the drug’s ongoing regulatory reviews in the US, EU, and China for immune thrombocytopenia (ITP), with a fast track decision expected by August 29, 2025. Clinical trials have provided encouraging results, showing that rilzabrutinib significantly improves response rates and disease markers in wAIHA and reduces disease flares in IgG4-RD while maintaining a consistent safety profile. The designation underscores the company’s commitment to developing innovative therapies for rare, immune-mediated diseases.

(PRESS RELEASE) PARIS, 3-Apr-2025 — /EuropaWire/ — The US Food and Drug Administration (FDA) has granted orphan drug designation to rilzabrutinib, a novel, advanced, oral, reversible Bruton’s tyrosine kinase (BTK) inhibitor, for the treatment of two rare conditions—warm autoimmune hemolytic anemia (wAIHA) and IgG4-related disease (IgG4-RD). These diseases, which currently have no approved treatments, affect fewer than 200,000 people in the US, underscoring a critical unmet medical need. Rilzabrutinib’s designation comes as part of a broader regulatory review that includes its potential application in immune thrombocytopenia (ITP) across the US, EU, and China. The FDA has also granted orphan drug status to rilzabrutinib for ITP in the US, EU, and Japan, with its ITP fast track review target decision date set for August 29, 2025.

Karin Knobe, MD, PhD, Global Head of Development for Rare Diseases, stated, “Orphan drug designation for these two rare, immune-mediated conditions validates our ongoing commitment to pursuing potential first- and best-in-class medicines for diseases that affect small populations but persist with unmet medical need. Our continued exploration of rilzabrutinib across multiple indications speaks to our belief in its potential for multi-immune modulation, as well as our belief in supporting treatment options, no matter how rare a condition.”

Supporting the designation, data from clinical trials have shown promising outcomes. In a phase 2b study for wAIHA (clinical study identifier: NCT05002777) presented at ASH 2024, rilzabrutinib demonstrated clinically meaningful improvements in response rate and disease markers. Similarly, a phase 2a study (clinical study identifier: NCT04520451) in IgG4-RD patients indicated that 52 weeks of treatment with rilzabrutinib reduced disease flare-ups, improved other disease markers, and allowed for glucocorticoid sparing. The safety profile observed in these studies was consistent with previous trials.

About rilzabrutinib
Rilzabrutinib is an investigational, oral, reversible, BTK inhibitor that has the potential to be a first- and best-in-class treatment of several immune-mediated diseases. BTK, expressed in B cells, macrophages, and other innate immune cells, plays a critical role in inflammatory pathways and multiple immune-mediated disease processes. With the application of Sanofi’s TAILORED COVALENCY® technology, rilzabrutinib can selectively inhibit the BTK target while potentially reducing the risk of off-target side effects. Based on its ability to drive multi-immune modulation, rilzabrutinib holds great promise in the treatment of multiple clinical indications.

About wAIHA
Affecting one to three people out of 100,000 in the US each year, wAIHA is a rare, potentially life-threatening, autoimmune disorder where autoantibodies lead to the premature destruction of the body’s own red blood cells (hemolysis). People living with wAIHA may experience debilitating fatigue, thromboembolism, dizziness, palpitations, and shortness of breath as the rate of production of new red blood cells in their bone marrow cannot compensate quickly enough for premature destruction of red blood cells.

About IgG4-RD
IgG4-RD affects approximatively eight out of 100,000 adult patients in the US each year and is a rare, progressive, relapsing, chronic fibro-inflammatory condition which can manifest in almost every organ and can lead to organ damage and irreversible dysfunction with a sometimes-fatal outcome.

About ITP
ITP is a rare, complex autoimmune disorder characterized by low platelet counts (less than 100,000/μL) resulting from both increased platelet destruction and decreased platelet production. Beyond bruising and bleeding, which can include potentially life-threatening episodes like intracranial hemorrhage, people living with ITP may experience arterial or venous thrombosis, which can result from the ITP itself, from other medical comorbidities, or may also be associated with the use of certain other ITP treatments. Additionally, people living with ITP often experience easily overlooked symptoms that can significantly impair their quality of life, such as unexplained fatigue, anxiety or depression, and cognitive impairment.

About Sanofi
We are an innovative global healthcare company, driven by one purpose: we chase the miracles of science to improve people’s lives. Our team, across the world, is dedicated to transforming the practice of medicine by working to turn the impossible into the possible. We provide potentially life-changing treatment options and life-saving vaccine protection to millions of people globally, while putting sustainability and social responsibility at the center of our ambitions.

Sanofi forward-looking statements
This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts. These statements include projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions, and expectations with respect to future financial results, events, operations, services, product development and potential, and statements regarding future performance. Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “intends”, “estimates”, “plans” and similar expressions. Although Sanofi’s management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of Sanofi, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and statements. These risks and uncertainties include among other things, the uncertainties inherent in research and development, future clinical data and analysis, including post marketing, decisions by regulatory authorities, such as the FDA or the EMA, regarding whether and when to approve any drug, device or biological application that may be filed for any such product candidates as well as their decisions regarding labelling and other matters that could affect the availability or commercial potential of such product candidates, the fact that product candidates if approved may not be commercially successful, the future approval and commercial success of therapeutic alternatives, Sanofi’s ability to benefit from external growth opportunities, to complete related transactions and/or obtain regulatory clearances, risks associated with intellectual property and any related pending or future litigation and the ultimate outcome of such litigation, trends in exchange rates and prevailing interest rates, volatile economic and market conditions, cost containment initiatives and subsequent changes thereto, and the impact that global crises may have on us, our customers, suppliers, vendors, and other business partners, and the financial condition of any one of them, as well as on our employees and on the global economy as a whole. The risks and uncertainties also include the uncertainties discussed or identified in the public filings with the SEC and the AMF made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in Sanofi’s annual report on Form 20-F for the year ended December 31, 2024. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.

FDA Grants Orphan Drug Status to Sanofi’s Rilzabrutinib: A New Hope for wAIHA, IgG4-RD, and Beyond

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