Sanofi halts amlitelimab development for atopic dermatitis following pipeline review

Sanofi has discontinued the development of its investigational monoclonal antibody amlitelimab for moderate-to-severe atopic dermatitis (AD), concluding that the therapy does not offer a sufficient improvement over existing standards of care despite encouraging long-term efficacy and safety data.

The French biopharma confirmed it will no longer pursue global regulatory submissions for amlitelimab in AD following an ongoing strategic review of its research and development pipeline. The decision marks a significant shift for a programme that had previously been viewed as a potential next-generation immunology asset.

The move comes just months after Sanofi reported mixed Phase III results from its COAST clinical programme. While the studies met key efficacy endpoints in some analyses and demonstrated the potential for infrequent 12-week dosing, the data failed to consistently outperform placebo across all regulatory endpoints and fell short of expectations in an increasingly competitive atopic dermatitis landscape.

Strong data, but insufficient differentiation

Sanofi said its decision was based on the "totality of efficacy and safety evidence" generated throughout the development programme.

The long-term Phase III ESTUARY extension study demonstrated sustained clinical responses without relapse in patients aged 12 years and older with moderate-to-severe AD, alongside an emerging safety profile consistent with previous studies. However, the company concluded that amlitelimab would not represent a meaningful advance over currently available therapies.

The findings underline the increasingly high bar facing developers in atopic dermatitis, where established biologics such as Dupixent and a growing pipeline of next-generation immunology medicines have intensified competition.

Additional data from the ESTUARY study and the wider clinical programme are expected to be presented at a forthcoming medical meeting.

Setback for a once-promising pipeline asset

Amlitelimab was acquired as part of Sanofi's $1.1 billion acquisition of Kymab in 2021 and was widely regarded as one of the company's most important late-stage pipeline assets. The fully human monoclonal antibody targets OX40 ligand (OX40L), a key immune regulator involved in the early stages of inflammatory disease, with the aim of reducing T-cell-mediated inflammation without depleting T cells.

Earlier this year, Sanofi had indicated it intended to seek regulatory approval based on the overall body of Phase III data. However, following further evaluation, the company has now concluded that the benefit-risk profile does not justify commercialisation in atopic dermatitis.

Focus shifts to broader immunology pipeline

Despite the setback, Sanofi reaffirmed its commitment to developing new treatments for inflammatory skin diseases, highlighting the ongoing need for additional therapies to address the heterogeneous immune mechanisms underlying atopic dermatitis.

The company also confirmed that the Phase II study evaluating amlitelimab in coeliac disease remains ongoing, with results expected during the second half of 2026.

Sanofi said it will work closely with investigators, clinical sites and regulators to wind down ongoing atopic dermatitis studies while ensuring appropriate continuity of care for enrolled patients.

The company added that the decision will have no impact on its financial guidance for the 2026 financial year.