Hellerup, Denmark, November 22, 2023 – UNION therapeutics A/S (UNION), a privately-held, clinical stage, pharmaceutical development company focused on immunology, today announced publication of a paper presenting full results from the IASOS Phase 2b study of orismilast for the treatment of moderate to severe psoriasis in the peer-reviewed Journal of the American Academy of Dermatology (JAAD).


The paper co-authored with the IASOS signatory investigator and leading experts within immune dermatology highlights the outcomes of the IASOS Phase 2b study. IASOS was a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study assessing the efficacy and safety of orismilast in adult patients with moderate to severe plaque psoriasis. 202 patients were randomized in the study with patients receiving one of three active doses (20, 30 or 40 mg) or placebo administered twice daily. The study was conducted at clinical sites in the US, the UK, Germany, and Poland.


Orismilast showed a statistically significant improvement (P<0.001) in percentage PASI reduction from baseline to week 16 for all doses (52.6% – 63.7%). The benefits in change of PASI were observed early, and already significant at the first point of measure at week 4.


39.5% to 49.0% of patients saw a reduction of at least 75% of their disease severity (PASI75) and 22.0% to 28.3% reached PASI90 indicating a deeper response than what has previously been observed with PDE4 inhibitors. These data support the potential of orismilast as a next-generation, high potency PDE4-inhibitor that provides increased potency than previous pan-PDE4’s. 1)


No new safety signals were identified with orismilast which confirms the general safety profile of PDE4i’s with manageable and well-characterized adverse event (AE) profile. The most common AEs (≥5%) were gastrointestinal events, headaches, and dizziness and the AEs were generally mild to moderate in severity and occurred primarily within the first 4 weeks. 1)


Topline results from the IASOS study were reported in January 2023 and presented at leading scientific conferences, AAD and EADV, during 2023.


Prof. Richard Warren, MBChB (hons), PhD, FRCP, Dermatology Centre Lead and Director of the Dermatopharmacology Unit, The University of Manchester, and Lead Investigator of the Phase 2b study said: 

“A strong unmet need remains for oral medicines in psoriasis, as many patients are undertreated or are dissatisfied with current options. The promising topline data from the IASOS study illustrates that selective potent PDE4 inhibition by orismilast offers the potential for additional efficacy in combination with a well-known safety profile from the PDE4 class.”

Kim Kjøller, Chief Executive Officer of UNION therapeutics said:

As our knowledge of PDE4 subtypes is evolving, orismilast shows promising results in inflammatory skin diseases such as psoriasis and hidradenitis suppurativa (HS). The data from IASOS Phase 2b study with orismilast confirms the clinical relevance of orismilast as a next-generation, high potency PDE4B/D inhibitor. Orismilast holds the potential to offer a best-in-class oral therapy for the treatment of psoriasis with higher potency and selectivity driving the better efficacy.”


About orismilast

Orismilast is a next generation, high potency PDE4 inhibitor targeting the PDE4B/D subtypes linked to inflammation, demonstrating potent inhibition of Th1, Th2 and Th17 pathways. It acts early in the inflammation cascade, inducing a broad range of anti-inflammatory effects across multiple cytokines involved in many dermatological and immunological diseases. 2)

UNION is developing orismilast as an oral treatment, based on the well-known safety profile of the PDE4 class, across immunology, initially targeting best-in-class or first-in-class positions driven by PDE4B/D subtype selectivity in atopic dermatitis, hidradenitis suppurativa and psoriasis.

The FDA has cleared UNION’s Investigational New Drug (IND) application for oral orismilast and granted Fast Track designation for oral orismilast for the treatment of moderate to severe AD as well as for the treatment of moderate to severe HS.


1)       Warren, R.B. et al., JAAD 2023: https://pubmed.ncbi.nlm.nih.gov/37951245/

2)       Blauvelt A et al., Dermatology and Therapy 2023: Next Generation PDE4 Inhibitors that Selectively Target PDE4B/D Subtypes: A Narrative Review – PubMed (nih.gov) &

Silverberg J.I. et al., JEADV 2022: https://onlinelibrary.wiley.com/doi/10.1111/jdv.18818  &

Warren R.B. et al., JEADV 2022: https://onlinelibrary.wiley.com/doi/10.1111/jdv.18812 &




Morten Boesen, Chief Financial Officer, UNION therapeutics A/S

+45 2381 5487

[email protected]


Sarah Toft-Jørgensen, Director of Communications and IR, UNION therapeutics A/S

+45 5385 3044

[email protected]


About UNION therapeutics

UNION therapeutics is a privately held, mid-to late-stage, pharmaceutical development company advancing novel treatment options within immunology. UNION is headquartered in Hellerup, Denmark, and led by an international team of biotech entrepreneurs and seasoned pharma executives, with a track record of developing and launching more than fifteen marketed drugs. Read more at http://www.uniontherapeutics.com