Sanofi (NASDAQ: SNY) reported Phase III data from three trials of amlitelimab in moderate-to-severe atopic dermatitis, showing that the anti-OX40L antibody met primary endpoints across monotherapy and combination settings — with efficacy at a dosing interval of once every 12 weeks that matched the every-four-week regimen. The results, presented as late-breaking research at the 2026 American Academy of Dermatology annual meeting in Denver, position amlitelimab as a mechanistically distinct entrant into a treatment landscape that has grown crowded but remains defined by frequent dosing and incomplete responses.
The COAST 1 and COAST 2 trials were randomized, double-blind, placebo-controlled Phase III studies evaluating amlitelimab monotherapy in adults and adolescents aged 12 and older with moderate-to-severe atopic dermatitis. SHORE used the same design but tested amlitelimab in combination with topical corticosteroids, with or without topical calcineurin inhibitors. Across the three trials, 1,786 patients were enrolled at sites spanning North America, Europe, Asia, and Latin America.
The primary endpoint for all three studies was the proportion of patients achieving a validated Investigator Global Assessment for atopic dermatitis (vIGA-AD) score of 0 or 1 — clear or almost clear skin — with at least a two-point reduction from baseline at Week 24. Both the Q4W and Q12W amlitelimab arms met this endpoint in each trial.For US and US reference countries, the primary endpoint was vIGA-AD 0/1 with a ≥2-point reduction. Of note, for the EU reference countries and Japan, the studies used co-primary endpoints that included the same vIGA-AD measure plus EASI-75.
In COAST 1, vIGA-AD 0/1 rates were 21.1% (Q4W) and 22.5% (Q12W) versus 9.2% for placebo. EASI-75 — the proportion of patients achieving at least 75% improvement in the Eczema Area and Severity Index — reached 35.9% and 39.1% in the Q4W and Q12W arms, respectively, compared to 19.1% for placebo. Itch reduction, measured by a four-point or greater decrease in peak pruritus numerical rating scale, was 22.5% (Q4W) and 24.5% (Q12W) versus 12.7% for placebo. All key secondary endpoints in COAST 1 reached statistical significance.
COAST 2 showed a similar pattern, with vIGA-AD 0/1 rates of 25.3% (Q4W) and 25.7% (Q12W) versus 14.8% for placebo. EASI-75 and itch endpoints reached nominal significance, though one secondary endpoint — vIGA-AD 0/1 with barely perceptible erythema — did not achieve statistical significance. The distinction between the two monotherapy trials is worth noting: COAST 2’s higher placebo response rate narrowed the treatment delta, a common challenge in atopic dermatitis trials with geographically diverse enrollment.
SHORE, the combination study, produced the highest absolute response rates. vIGA-AD 0/1 was achieved by 28.7% (Q4W) and 32.3% (Q12W) of patients versus 16.8% on placebo plus topical therapy alone. EASI-75 reached 48.1% and 46.8% in the active arms versus 32.3% for placebo. All primary and key secondary endpoints were statistically significant.
Across all three trials, Sanofi reported that efficacy was progressively increasing at Week 24 with no evidence of plateau, suggesting that longer treatment durations may yield higher response rates — a pattern that will be tested in the ongoing ESTUARY extension study.
The safety profile was consistent with earlier-phase data. The most common adverse events across COAST 1, COAST 2, and SHORE were nasopharyngitis, atopic dermatitis flares, and upper respiratory tract infections, occurring at rates generally comparable to or lower than placebo. Malignancy rates were below 1% and similar between active and placebo groups. No severe injection site reactions or serious gastrointestinal ulceration events were reported.
Sanofi disclosed a second case of Kaposi’s sarcoma in the amlitelimab development program, identified in the still-blinded ESTUARY Phase III extension study. Both Kaposi’s sarcoma cases occurred in patients with known risk factors, and both patients discontinued treatment and entered recovery. Out of an estimated 3,778 patients exposed to amlitelimab across all indications, no additional cases have been identified. The signal remains numerically small but warrants monitoring given the immunomodulatory mechanism. Sanofi stated that it “believes that amlitelimab continues to have the potential to be a meaningful and convenient option for patients with AD”.
Amlitelimab is a fully human, non-T cell depleting monoclonal antibody that blocks OX40 ligand, a costimulatory molecule involved in the activation and survival of effector T cells. By targeting this upstream pathway, the drug aims to modulate pathogenic immune responses without the broad immunosuppression associated with JAK inhibitors or the cytokine-specific blockade of IL-4/IL-13 antibodies. The non-depleting design distinguishes it from therapies that reduce T cell populations, potentially offering a different safety-efficacy tradeoff.
The atopic dermatitis treatment landscape in 2026 includes six approved systemic therapies for moderate-to-severe disease: dupilumab and tralokinumab (both anti-IL-4/IL-13 pathway), lebrikizumab (anti-IL-13), nemolizumab (anti-IL-31 receptor), and the oral JAK1 inhibitors abrocitinib and upadacitinib. All approved injectable biologics require dosing every two to four weeks. Amlitelimab’s Q12W regimen — approximately four injections per year — would represent a substantial reduction in treatment burden if the dosing schedule is maintained in regulatory filings. Cross-trial comparisons are limited by differences in study populations, placebo rates, and endpoint definitions, but the absolute vIGA-AD 0/1 and EASI-75 rates observed in the COAST and SHORE trials are numerically lower than those reported for dupilumab and upadacitinib in their respective pivotal programs. Whether the dosing convenience and mechanistic novelty offset the apparent efficacy gap will be a central question for regulators, payers, and prescribers.
Rocatinlimab, developed by Amgen, targets the OX40 receptor rather than the ligand and is also in Phase III development for atopic dermatitis. The two drugs represent competing approaches to the same pathway, and their relative clinical profiles will become clearer as more data emerge. A 2024 review in the Journal of Dermatology and Therapy examined both molecules, noting that while they share a pathway target, their binding sites and downstream effects may differ.
Results from ESTUARY, evaluating Q12W maintenance dosing and longer-term safety, are anticipated in the second half of 2026.
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