Phase 3 Data Show Amlitelimab Effective in Adults, Adolescents with Atopic Dermatitis

New findings suggest amlitelimab treatment, administered every 4 or every 12 weeks, leads to significant skin clearance and reduction in severity versus placebo among patients with atopic dermatitis at Week 24.1

These phase 3 data, announced by Sanofi SA on September 4, were the result of the global COAST 1 trial (NCT06130566) evaluating amlitelimab, a fully human, non–T-cell depleting monoclonal antibody directed against OX40-ligand (OX40L). The study assessed patients aged 12 years and older who live with moderate-to-severe atopic dermatitis.

“These positive first phase 3 results of amlitelimab reinforce the potential of targeting the OX40-ligand to normalize the overactive immune system, without depleting T cells,” Houman Ashrafian, executive vice president and head of research & development at Sanofi, said in a statement.1 “Amlitelimab may represent a significant advance in the treatment of atopic dermatitis with clinically meaningful and progressively increasing efficacy, with the potential of dosing only four times per year.”

Amlitelimab blocks OX40L, an important immune pathway regulator, while preserving T-cell populations. Through its use, the drug is designed to help rebalance overactive immune responses without T-cell depletion. Beyond its lead indication of moderate-to-severe atopic dermatitis, amlitelimab is being explored for several immune-mediated conditions, such as moderate-to-severe asthma and alopecia areata.

The COAST 1 trial was a randomized, double-blind, placebo-controlled, multicenter phase 3 study with 3 parallel arms, spanning 15 countries worldwide. The study involved 601 adolescents and adults, with all patients being ≥12 years and having been diagnosed with atopic dermatitis. The subjects were treated subcutaneously with amlitelimab at 250 mg (or 125 mg if <40 kg) on either a Q4W or Q12W schedule following a loading dose of 500 mg (250 mg if <40 kg).

The study’s efficacy endpoints were tailored by region. For example, the primary endpoint in the US was the proportion of individuals attaining a validated Investigator Global Assessment for atopic dermatitis (vIGA-AD) score of 0 (clear) or 1 (almost clear), in addition a ≥2-point reduction from baseline. In the European Union, EU reference countries, and Japan, the study’s co-primary endpoints included vIGA-AD 0/1 with a ≥2-point reduction and attainment of a 75% improvement from baseline at minimum in the Eczema Area and Severity Index (EASI-75). Both Q4W and Q12W dosing arms met these endpoints.1

In looking at key secondary measures, COAST 1 investigators found that these were also reached at Week 24. Such endpoints included the percentage of subjects with a vIGA-AD 0/1 and only barely visible erythema plus a ≥2-point improvement from the point of baseline. They also looked at the proportion of subjects experiencing a ≥4-point reduction in peak pruritus numerical rating scale (PP-NRS) scores among participants with a baseline PP-NRS ≥4.

In COAST 1 investigators’ evaluation of treatment-emergent adverse events (TEAEs), they concluded that TEAEs had been generally balanced between the amlitelimab and placebo arms. The most frequent TEAEs (≥5% in any cohort of the study) had included atopic dermatitis, nasopharyngitis, and upper respiratory tract infection, all of which appeared more often in the placebo arm.

They highlighted that Injection site reactions were slightly higher among those treated with amlitelimab (2.2% pooled versus 0.7% placebo, respectively). Such reactions, however, were noted asmild, resolved, and not disruptive of anyone’s treatment. They highlighted low rates of pyrexia (1.1% pooled amlitelimab versus 0.7% placebo) and chills (0.4% pooled amlitelimab versus 0% placebo). Overall, TEAEs, serious adverse events, and discontinuations resulting from TEAEs were shown to be comparable between the amlitelimab and placebo groups.

“These promising data seen in a study population that more closely resembles today’s diverse patient landscape, including a substantial proportion previously treated with advanced therapies, support our ambition to deliver a differentiated medicine,” Ashrafian said in his statement.1 “We look forward to sharing additional phase 3 results from the OCEANA clinical development program.”

These positive findings on amlitelimab are similar to results observed in the recent phase 2b STREAM-AD trial, with findings indicating an acceptable safety profile and efficacy in moderate-to-severe atopic dermatitis over 68 weeks.2 The COAST 1 study is part of the larger OCEANA development program, which also includes the SHORE, COAST 2, AQUA, and ESTUARY phase 3 studies.1

References

1. Press Release: Sanofi’s amlitelimab met all primary and key secondary endpoints in the COAST 1 phase 3 study in adults and adolescents with atopic dermatitis. Sanofi. September 4, 2025. https://www.sanofi.com/en/media-room/press-releases/2025/2025-09-04-05-00-00-3144170?utm_campaign=sc_eoe&utm_source=linkedin_global&utm_medium=social&utm_content=300001900091476.

2. Derman C. Phase 2b Data Shows Amlitelimab’s 68-Week Safety for Atopic Dermatitis. HCPLive. June 26, 2025. Accessed September 4, 2025. https://www.hcplive.com/view/phase-2b-data-shows-amlitelimab-s-68-week-safety-for-atopic-dermatitis.