Sanofi Completes Key Amlitelimab Vaccine-Response Study in Atopic Dermatitis

Sanofi (SNYNF) announced an update on their ongoing clinical study.

Sanofi has completed a Phase 2 study titled “A Randomized, Double-blind, Placebo-controlled Phase 2 Study to Evaluate the Effect of Amlitelimab on Vaccine Antibody Responses in Adult Participants With Moderate to Severe Atopic Dermatitis.” The trial looked at how well adults with moderate to severe atopic dermatitis respond to common vaccines while being treated with amlitelimab versus placebo. The focus is on whether the drug affects the body’s ability to build protection after vaccination, a key point for long-term safety and use in a broad patient population.

The main treatment under review is amlitelimab, given as a subcutaneous injection. It is being developed as an anti-inflammatory therapy for moderate to severe atopic dermatitis. In the study, all participants received standard non-live vaccines (a Tdap vaccine and a pneumococcal polysaccharide vaccine) alongside either amlitelimab or placebo. The aim is to show that amlitelimab does not blunt normal vaccine responses while still controlling skin disease.

The study used a randomized, parallel-group design, meaning participants were randomly placed into either the amlitelimab arm or the placebo arm and stayed in that group. It was triple-blind, so patients, doctors, and study staff did not know who got the active drug. The trial’s main goal was treatment-focused: to see how amlitelimab affects vaccine antibody responses and to monitor safety when used with routine vaccines in this patient group.

The trial started after submission in August 2023 and has a total duration of up to 36 weeks per participant, including screening, 16 weeks of treatment, and safety follow-up. The main vaccine response measures were taken at Week 16, which effectively acts as the primary completion point for efficacy data. The overall study is now listed as completed, and the latest update on ClinicalTrials was posted on January 23, 2026, signaling that data collection is finished, but results have not yet been posted.

For investors, this update matters because it addresses a key safety and usability question for amlitelimab: can patients stay on the drug and still get normal protection from routine vaccines. A clean readout here would support amlitelimab’s profile as a long-term therapy and could strengthen Sanofi’s position in atopic dermatitis, where it already competes with Dupixent and faces pressure from JAK inhibitors and other biologics. Positive vaccine-response data would likely improve confidence in amlitelimab’s commercial potential and support sentiment around Sanofi’s broader immunology pipeline, while negative or unclear results could raise questions about widespread use and limit peak sales assumptions.

The study is now completed and recently updated, with more details and any forthcoming results to be made available on the ClinicalTrials portal.

To learn more about SNYNF’s potential, visit the Sanofi drug pipeline page.