Amlitelimab

Sanofi halted a phase 2 trial testing a monoclonal antibody, SAR445399, in non-cystic fibrosis bronchiectasis, Fierce Biotech has learned. The trial , which began only back in April, was a randomized, double-blind, placebo-controlled study to measure the reduction in mucus plug score following treatment with SAR445399 compared with placebo in adults aged 18 to 80 years with NCFB, a chronic lung disease. The trial was officially reported as halted on July 29, the day before Sanofi’s second-quarter earnings call. The decision to pause the trial was made “as part of a company-wide portfolio review for strategic business reasons,” and not due to safety concerns, a Sanofi spokesperson told Fierce. The move to pause the NCFB trial comes during a trying time for Sanofi following a year filled with a series of trial fails . In February, the French pharma ousted CEO Paul Hudson and appointed Merck KGaA leader Belén Garijo, M.D., Ph.D., to steer the ship. Since then, Garijo has been doing a deep dive on correcting the company’s strewn R&D and clinical strategies. On July 24, Sanofi scrapped amlitelimab for atopic dermatitis, despite its lore as being a potential $5 billion blockbuster. During its second-quarter report, the company abandoned two more assets, balinatunfib and itepekimab, following failed trial results in psoriasis and chronic obstructive pulmonary disease , respectively. SAR445399 , only first revealed by Sanofi in 2023, is an anti-interleukin-1 receptor 3 monoclonal antibody developed to block the interleukin 1, 33, and 36 cytokine pathways. These pathways can be important in chronic immune-related dermatologic diseases, such as atopic dermatitis and hidradenitis suppurativa, as well as respiratory conditions, such as NCFB. NCFB affects roughly half a million people in the U.S., with a global incidence of greater than one million cases. In August 2025, Insmed received FDA approval for Brinsupri , a DPP1 inhibitor targeting neutrophil activation, for treatment of NCFB in adults and kids ages 12 and older. The British biotech Infex Therapeutics showed promising NCFB phase 2a data using their monoclonal antibody, INFEX702 , which acts by disabling Pseudomonas aeruginosa, a bacteria known to be a major pathogen of NCFB. Sanofi is currently running a separate phase 2 study testing SAR445399 as a potential treatment for the inflammatory skin condition hidradenitis suppurativa.

Sanofi announces decision not to submit amlitelimab in atopic dermatitis for global regulatory reviews Paris, July 24, 2026. Sanofi today announced the discontinuation of clinical development of amlitelimab, an OX40-ligand monoclonal antibody, in moderate-to-severe atopic dermatitis (AD). This decision not to submit for global regulatory reviews was made as part of an ongoing strategic assessment of the pipeline. Sanofi has determined that the totality of efficacy and safety evidence generated to date does not support further development of amlitelimab in AD. While the ESTUARY phase 3 long-term extension study (clinical study identifier: NCT06407934 ) showed long-term maintenance of clinical response without relapse in patients aged 12 years and older with moderate-to-severe AD and an emerging safety pro builds on previous data, amlitelimab would not represent a meaningful improvement to the standard of care for patients with AD. Additional results from the amlitelimab development program in AD, including from the ESTUARY study, will be presented at a forthcoming medical meeting. Patients and their physicians need additional effective treatments due to the heterogeneity of underlying immune mechanisms that contribute to AD, and Sanofi remains committed to pursuing advances in inflammatory skin conditions. ezstandalone.cmd.push(function () { ezstandalone.showAds(131); }); Sanofi is deeply grateful to the patients, caregivers, and investigators who supported the development of amlitelimab in AD, including in the ESTUARY study. Sanofi will work closely with investigators, site teams, and regulatory authorities to ensure a wind-down of ongoing amlitelimab AD studies, with appropriate transition of care for all enrolled patients. Financial considerations Sanofi is not amending its full-year 2026 guidance as a result of this announcement. About amlitelimab Amlitelimab (SAR445229, KY1005) is a fully human, non-T cell depleting monoclonal antibody that blocks the OX40L, a key immune regulator. With its novel mechanism of action, amlitelimab selectively blocks OX40L signaling during the inflammatory prequel, the initiating phase of an overactive immune system, to potentially normalize T-cell-mediated inflammation without T-cell depletion. The phase 2 study of amlitelimab in celiac disease is ongoing and expected to readout in the second half of 2026. 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 Media Relations Sandrine Guendoul | +33 6 25 09 14 25 | sandrine.guendoul@sanofi.com Evan Berland | +1 215 432 0234 | evan.berland@sanofi.com Léo Le Bourhis | +33 6 75 06 43 81 | leo.lebourhis@sanofi.com Victor Rouault | +33 6 70 93 71 40 | victor.rouault@sanofi.com Timothy Gilbert | +1 516 521 2929 | timothy.gilbert@sanofi.com Léa Ubaldi | +33 6 30 19 66 46 | lea.ubaldi@sanofi.com Ekaterina Pesheva | +1 410 926 6780 | ekaterina.pesheva@sanofi.com Sanofi Investor Relations Thomas Kudsk Larsen |+44 7545 513 693 | thomas.larsen@sanofi.com Alizé Kaisserian | +33 6 47 04 12 11 | alize.kaisserian@sanofi.com Keita Browne | +1 781 249 1766 | keita.browne@sanofi.com Nathalie Pham | +33 7 85 93 30 17 | nathalie.pham@sanofi.com Nina Goworek | +1 908 569 7086 | nina.goworek@sanofi.com Thibaud Châtelet | +33 6 80 80 89 90 | thibaud.chatelet@sanofi.com Yun Li | +33 6 84 00 90 72 | yun.li3@sanofi.com 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. 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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 ForwardLooking 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. Attachment Amlitelimab Press Release-EN