Sanofi has announced termination of global regulatory submissions and clinical development of amlitelimab, a fully human non-T-cell-depleting OX40L monoclonal antibody (mAb), for moderate-to-severe atopic dermatitis. The decision follows a strategic assessment of three Phase III trials – COAST 1, COAST 2 and SHORE – where amlitelimab achieved statistically significant but commercially suboptimal response rates (EASI-75 of 35.9% to 48.1% versus 19.1% to 32.3% for placebo across regimens), and a separate ESTUARY maintenance study showing durable response without new safety signals. Sanofi concluded the dataset does not support positioning amlitelimab as a differentiated standard-of-care in a market segment already served by dupilumab, upadacitinib, and emerging IL-13 or OX40L competitors.

Amlitelimab remains the only OX40L antibody in Phase III globally, with Sanofi expected to refocus resources on asthma, hidradenitis suppurativa, and other inflammatory indications where the mechanism's T-regulatory preservation profile may offer clearer advantage. The withdrawal illustrates the escalating efficacy bar in atopic dermatitis, where marginal improvements over dupilumab no longer justify launch investment, and where ultra-long-acting IL-13 agents such as zumilokibart are reshaping the competitive benchmark.