IL-22 might be a novel target in the therapy of moderate-to-severe atopic dermatitis (AD). In a first phase 2a study, an investigative IL-22 receptor blocker achieved all primary and secondary endpoints and was well tolerated.


A novel approach for the treatment of moderate-to-severe AD was the topic of discussion at the 2023 American Academy of Dermatology annual meeting1. Diamond Thaçi, MD, presented the results of a phase 2a, randomized, double-blind, placebo-controlled proof of concept trial to assess the efficacy and safety of LEO138559, a monoclonal antibody that specifically targets the IL-22 receptor, blocking signaling of IL-22 and potentially also IL-20 and IL-24.

In the study, a total of 58 patients were randomized 1:1 to receive the agent or placebo every 2 weeks for 16 weeks, followed by a 16-week safety follow-up. At week 16, the primary study endpoint of the Eczema Area and Severity Index (EASI) was -15.3 in the participants treated with LEO138559, a 65.4% improvement compared with -3.5 in the placebo group (P=0.003).

“The agent really works fast, Dr. Thaçi said, adding that “the antibody was superior regarding all secondary endpoints, namely EASI-75, EASI-90, and EASI-100 response and in the investigator’s global assessment.” In LEO138559, which also had a pronounced antipruritic effect, 20% of participants that received the active ingredient achieved a reduction in a numerical rating scale of 4 or more, compared with 7 in the placebo group (P=0.14).

Besides one case of conjunctivitis, the new antibody showed good tolerability with no serious adverse events.

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