Sanofi will not seek global approval for amlitelimab in atopic dermatitis after Phase 3 ESTUARY data showed durable safety and efficacy but limited differentiation.
Written By: Anshu Gupta, PharmD
Reviewed By: Pharmacally Editorial Team
Sanofi will not pursue global regulatory submissions for amlitelimab in moderate-to-severe atopic dermatitis after concluding that the therapy does not offer a meaningful clinical advantage over current treatment options. The decision follows a strategic pipeline review despite durable long-term efficacy and a consistent safety profile observed in the Phase 3 ESTUARY extension study.
Sanofi has discontinued the clinical development of amlitelimab for moderate-to-severe atopic dermatitis (AD) and will not pursue global regulatory submissions for the investigational therapy in this indication. The decision follows an ongoing strategic assessment of the company’s pipeline after determining that the overall efficacy and safety evidence does not support further development or regulatory review for AD.
The decision reflects Sanofi’s assessment of amlitelimab’s overall clinical value rather than the emergence of a new safety concern. Although long-term data demonstrated sustained disease control and a safety profile consistent with previous studies, the company concluded that the therapy would not provide a meaningful improvement over the current standard of care.
Long-Term Phase 3 Results Supported Durable Disease Control
Sanofi’s decision comes after results from the ESTUARY Phase 3 long-term extension study (NCT06407934), which evaluated adolescents and adults aged 12 years and older with moderate-to-severe atopic dermatitis.
The extension study showed that patients maintained their clinical response without relapse during long-term treatment. The trial also generated additional safety data that remained consistent with the therapy’s previously established safety profile.
Despite these positive long-term findings, Sanofi determined that the overall efficacy profile was not sufficiently differentiated from existing therapies to justify regulatory submissions or continued investment in atopic dermatitis.
Additional analyses from the ESTUARY study and the broader amlitelimab development program are expected to be presented at a forthcoming medical meeting.
Competitive Treatment Landscape Raised the Bar
Treatment options for moderate-to-severe atopic dermatitis have expanded rapidly in recent years with the availability of IL-4 receptor alpha (IL-4Rα) inhibitors, IL-13 inhibitors, and oral Janus kinase (JAK) inhibitors, establishing increasingly high expectations for efficacy, durability, and patient outcomes.
Against this evolving landscape, Sanofi concluded that amlitelimab did not demonstrate sufficient clinical differentiation to represent a meaningful advance over current standards of care, despite its favorable long-term safety and durability profile.
A Novel Mechanism Remains Under Investigation
Amlitelimab (SAR445229, KY1005) is a fully human, non-T-cell-depleting monoclonal antibody that targets OX40 ligand (OX40L), an important regulator of early immune activation.
By selectively blocking OX40L signaling during the initial phase of immune activation, the therapy was developed to reduce T-cell-mediated inflammation while preserving immune cell populations. This differentiated mechanism sought to intervene earlier in the inflammatory cascade than many currently approved therapies.
Atopic dermatitis is a chronic inflammatory skin disease driven by complex and heterogeneous immune pathways. Although biologics and targeted oral therapies have improved disease management, many patients continue to require additional treatment options because responses vary across individuals.
Transition of Ongoing Studies
Sanofi will work with investigators, clinical sites, and regulatory authorities to wind down ongoing atopic dermatitis studies while ensuring appropriate transition of care for enrolled participants.
The company expressed its appreciation to patients, caregivers, investigators, and research teams who participated in the amlitelimab clinical development program, including the ESTUARY study.
Commercial Outlook and Future Development
The discontinuation of amlitelimab in atopic dermatitis does not affect Sanofi’s full-year 2026 financial guidance.
Development of amlitelimab continues outside atopic dermatitis. The ongoing Phase 2 clinical trial in celiac disease remains active, with topline results expected during the second half of 2026.
Sanofi reaffirmed its commitment to advancing innovation in immunology and inflammatory skin diseases, emphasizing that the unmet need in atopic dermatitis remains substantial because of the disease’s diverse underlying immune mechanisms. While amlitelimab will no longer advance toward regulatory review in AD, the company continues to invest in therapies that can deliver meaningful clinical improvements for patients across immune-mediated diseases.
Reference
Press Release: Sanofi announces decision not to submit amlitelimab in atopic dermatitis for global regulatory reviews
