BALLERUP, Denmark, MARCH 18, 2023 – LEO Pharma A/S, a global leader in medical dermatology, today announced that a Phase 2a trial evaluating the efficacy and safety of investigational agent LEO 138559 in adults with moderate-to-severe atopic dermatitis met its primary endpoint. Results were shared as one of two LEO Pharma late breaker oral presentations at the 2023 American Academy of Dermatology (AAD) Annual Meeting.1 LEO 138559 is an investigational agent and its efficacy and safety are subject to further larger trials.

LEO 138559 is an investigational monoclonal antibody currently in Phase 2 development for the treatment of moderate-to-severe atopic dermatitis, which blocks the IL-22RA1 receptor subunit thereby inhibiting the effect of the interleukin-22 (IL-22) cytokine – known to be elevated in patients with atopic dermatitis.1–3 LEO 138559 potentially also inhibits to some extent the effects of cytokines IL-20 and IL-24; however, this remains to be fully understood.1

“We know that atopic dermatitis is a complex immunological condition and LEO Pharma is committed to supporting patients and clinicians in dermatology by finding new ways to treat this chronic disease,” said Jörg Möller, Executive Vice President, Global Research and Development, LEO Pharma. “We are encouraged by these Phase 2a results, in moderate-to-severe atopic dermatitis and plans are underway for a Phase 2b trial.”

The results from the Phase 2a trial in 58 adult patients showed that LEO 138559 dosed at 450 mg every other week (Q2W) via subcutaneous injections for 16 weeks had a favourable safety profile.1 LEO 138559 demonstrated significant improvement compared with placebo in the primary endpoint of change in EASI score from baseline (-15.3 vs. -3.5) and across a range of endpoints including EASI-75 (41.6% vs.13.7%), EASI-90 (30.8% vs. 3.5%), EASI-100 (20.9% vs. 0%) and vIGA-AD 0/1 (27.3% vs. 7.0%).1 The most frequently reported AEs in the LEO 138559 versus placebo arms were COVID-19 (13.8% vs 6.9%), dermatitis atopic (13.8% vs 13.8%), and upper respiratory tract infection (3.4% vs 10.3%).1

“These results are promising, as they demonstrate for the first time the potential benefits of targeting the IL-22 receptor which is a new mode of action”, said Professor Diamant Thaci, MD, Head of Institute and Comprehensive Center for Inflammation Medicine, University of Lübeck, Lübeck, Germany and the international coordinating investigator for the Phase 2a trial. “Patients with moderate-to-severe atopic dermatitis still face numerous unmet needs and we welcome any new advances that could provide us with additional options to help them.”

LEO Pharma and argenx BV formed a strategic alliance in 2015 to develop innovative antibody-based solutions for the treatment of chronic inflammation that underlies many skin conditions. LEO Pharma and argenx BV jointly developed LEO 138559 under an exclusive option and research agreement. LEO Pharma obtained the license to LEO 138559 in 2022 and now assumes the responsibility to develop and commercialize LEO 138559 for inflammatory skin disorders, such as atopic dermatitis.

The collaboration between LEO Pharma and argenx BV stands as a strong example of an external innovation sourcing model, which is a key pillar in LEO Pharma’s new Research and Development strategy.