Sanofi Stops Riliprubart MOBILIZE Trial After Independent Committee Finds Study Unlikely to Show Sufficient Efficacy

(IN BRIEF) Sanofi will stop the MOBILIZE phase 3 study of riliprubart in patients with chronic inflammatory demyelinating polyneuropathy who are refractory to standard-of-care treatment after an independent data monitoring committee determined through an interim analysis that the study was unlikely to show sufficient efficacy. The company said no riliprubart-related safety signals were identified as part of the review. Sanofi will now work with investigators and clinical site teams to wind down the MOBILIZE study and ensure appropriate transition of care for enrolled patients, while also conducting a full analysis of the trial data to inform future research and contribute to scientific understanding of CIDP. The company said the termination will not create significant financial cost and does not change its 2026 financial guidance. Other ongoing riliprubart studies, including the VITALIZE phase 3 study in IVIg-treated CIDP patients, will be evaluated accordingly. Riliprubart remains an investigational monoclonal antibody targeting activated C1s in the classical complement pathway, with the aim of addressing inflammatory mechanisms linked to demyelination and axonal damage in CIDP.

(PRESS RELEASE) PARIS, 10-Jun-2026 — /EuropaWire/ — Sanofi has announced that it will discontinue the MOBILIZE phase 3 clinical study evaluating riliprubart in patients with chronic inflammatory demyelinating polyneuropathy, or CIDP, who are refractory to standard-of-care treatment.

The decision follows an interim analysis by an independent data monitoring committee, which concluded that the MOBILIZE study was unlikely to demonstrate sufficient efficacy. Sanofi said no safety signals related to riliprubart were identified during the interim review.

The MOBILIZE study, listed under clinical study identifier NCT06290128, was designed to assess riliprubart in a group of CIDP patients whose disease does not respond adequately to existing standard therapies. Sanofi said the continuation of other ongoing riliprubart studies, including the VITALIZE phase 3 study in IVIg-treated CIDP patients, will be reviewed accordingly. The VITALIZE study is listed under clinical study identifier NCT06290141.

Sanofi expressed appreciation to the patients, caregivers and investigators who took part in the MOBILIZE trial. The company said it will work closely with investigators and clinical site teams to wind down the study in an orderly manner and support an appropriate transition of care for all enrolled patients.

The company also plans to carry out a detailed analysis of the MOBILIZE data. Sanofi said the findings will help guide future research decisions and contribute to broader scientific understanding of chronic inflammatory demyelinating polyneuropathy.

From a financial perspective, Sanofi said the termination of the MOBILIZE phase 3 study is not expected to result in any significant cost. The company also confirmed that there is no change to its financial guidance for 2026.

Riliprubart, also known as SAR445088 or BIVV020, is an IgG4 humanized monoclonal antibody designed to selectively inhibit activated C1s in the classical complement pathway of the innate immune system. By blocking C1s, riliprubart is intended to target inflammatory mechanisms that may contribute to demyelination and axonal damage in CIDP.

The therapy remains under clinical investigation, and its safety and efficacy have not been evaluated by any regulatory authority.

CIDP is a rare neurological disorder that causes progressive weakness and sensory problems in the arms and legs. The condition occurs when the immune system attacks the myelin sheaths surrounding nerve cells in the peripheral nervous system. Early diagnosis is important because treatment can help reduce the risk of long-term disability.

Despite existing therapies, many people with CIDP continue to experience residual symptoms such as weakness, numbness and fatigue, which can affect quality of life and contribute to long-term morbidity. Around 30% of people with CIDP do not respond to standard therapies, while among those who do respond, about 70% have an incomplete response. Fewer than one-third of people with CIDP remain in remission without continued treatment.

About riliprubart
Riliprubart (SAR445088, BIVV020) is an IgG4 humanized monoclonal antibody that selectively inhibits activated C1s in the classical complement pathway of the innate immune system. By blocking C1s, riliprubart has the potential to inhibit key inflammatory mechanisms that drive demyelination and axonal damage in CIDP. Riliprubart is currently under clinical investigation, and its safety and efficacy have not been evaluated by any regulatory authority. For more information on riliprubart clinical studies, please visit www.clinicaltrials.gov.

About CIDP
CIDP is a rare neurological condition that causes progressive weakness and sensory impairment in the arms and legs. CIDP occurs when the body’s immune system attacks the myelin sheaths around nerve cells in the peripheral nervous system. Timely diagnosis of CIDP is important because it allows for appropriate treatment, which is essential to preventing long-term disability. However, despite available therapies, many individuals are left with residual symptoms, including weakness, numbness, and fatigue that can lead to long-term morbidity and diminished quality-of-life. Approximately 30% of people with CIDP do not respond to standard therapies. In people with CIDP who do respond, about 70% of the response is considered incomplete. Less than one-third of people with CIDP remain in remission without continued therapy.

About Sanofi
Sanofi is an R&D driven, AI-powered biopharma company committed to improving people’s lives and delivering compelling growth. We apply our deep understanding of the immune system to invent medicines and vaccines that treat and protect millions of people around the world, with an innovative pipeline that could benefit millions more. Our team is guided by one purpose: we chase the miracles of science to improve people’s lives; this inspires us to drive progress and deliver positive impact for our people and the communities we serve, by addressing the most urgent healthcare, environmental, and societal challenges of our time. Sanofi is listed on EURONEXT: SAN and NASDAQ: SNY

Sanofi forward-looking statements
This press release contains forward-looking statements within the meaning of applicable securities laws, including 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 events and economic performance. Words such as “expect,” “anticipate,” “believe,” “intend,” “estimate,” “plan,” “can,” “contemplate,” “could,” “is designed to,” “may,” “might,” “potential,” “objective,” “attempt,” “target,” “project,” “strategy,” “strive,” “desire,” “predict,” “forecast,” “ambition,” “guideline,” “seek,” “should,” “will,” “goal,” or the negative of these, and similar expressions are intended to identify forward-looking statements. 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 U.S Food and Drug Administration or the European Medicines Agency, 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; unexpected regulatory actions or delays, or government regulation generally; authorities’ decisions regarding whether and when to approve a product candidate; political pressure in the United States to mandate lower drug prices including “most favored nation” pricing for State Medicaid programs; 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, including future clinical data and analysis of existing clinical data relating to the product, including post marketing, unexpected safety, quality or manufacturing issues, competition in general; 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 French Markets Authority (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, 2025, or contained in our periodic reports on Form 6-K. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements. In light of these risks, uncertainties, and assumptions, you should not place undue reliance on any forward-looking statements contained herein.

Sanofi Stops Riliprubart MOBILIZE Trial After Independent Committee Finds Study Unlikely to Show Sufficient Efficacy

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