Hellerup, Denmark, 9 January 2023 – UNION therapeutics A/S (UNION), a privately-held, multi-asset, clinical stage, pharmaceutical development company focused on immunology and infectious disease, today announces positive topline results from the IASOS Phase 2b study of oral orismilast in adult patients with moderate to severe psoriasis.  

Data from the 202 patients randomized and dosed in the study showed that all active arms of oral orismilast achieved the primary endpoint of percentage change in Psoriasis Activity and Severity Index (PASI) from baseline to week 16 measured against placebo, with statistical significance reached already at the first time point after 4 weeks of treatment. The results support the target product profile of a best-in-class PDE4 inhibitor and confirm the well-established favorable safety profile of PDE4 inhibition.

Orismilast has been developed as a more potent PDE4-inhibitor targeting a best-in-class position. This has been demonstrated in multiple preclinical and human biomarker studies, and is now further supported by secondary endpoints from the IASOS study, including PASI-90 and PASI-100.

UNION plans to present topline data at an upcoming dermatology conference.

Prof. Richard Warren, MBChB (hons), PhD, The University of Manchester and Consultant Dermatologist, Salford Royal NHS Foundation Trust, Signatory 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:

“We are delighted to report positive topline results from our Phase 2b study with oral orismilast in psoriasis. The results support the target product profile of orismilast as a high-potency oral PDE4 inhibitor with best-in-class potential, while at the same time benefiting from the favorable safety profile of the PDE4 class in general. The results also support the broader potential in immunology, where we are already running studies in atopic dermatitis and hidradenitis suppurativa with topline results expected later in 2023”.


About the IASOS Phase 2b study

The Phase 2b study is a randomized, double-blind, placebo-controlled, parallel-group, dose-ranging study to evaluate the efficacy and safety of orismilast MR tablet in adult patients with moderate to severe plaque psoriasis. The study included 202 patients randomized to receive 1 of 3 active doses or placebo administered twice daily. The study was conducted at clinical sites in the US, the UK, Germany, and Poland.

About orismilast

UNION is developing orismilast, a high-potency PDE4 inhibitor targeting the PDE4 subtypes linked to inflammation. It operates early in the inflammation cascade, inducing a broad range of anti-inflammatory effects across multiple cytokines involved in many dermatological and immunological diseases.1)

Orismilast holds the potential to become a safe and efficacious oral treatment for many immunological diseases, and UNION is currently developing oral orismilast for the treatment of AD, psoriasis, and HS.

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. In 2021, UNION entered a strategic partnership with Innovent Biologics for the development of orismilast in Mainland China, Hong Kong, Macau, and Taiwan.

About psoriasis and treatment of psoriasis

Psoriasis is a chronic, systemic, inflammatory skin disease that is diagnosed in an estimated 13 million patients in 2021 in the Seven Major Markets (US, UK, Germany, France, Italy, Spain and Japan)2). Plaque psoriasis is the most common variant and can appear on any area of the body, but most often appears on the scalp, knees, elbows, trunk, and limbs. Patients with psoriasis experience substantial morbidity and increased rates of inflammatory arthritis, cardiometabolic diseases, and mental health disorders3).

Psoriasis can be managed by topical, oral, and biological treatments as well as phototherapy. Depending on the severity of the disease, patients and treatments are selected in a stepwise manner4). Patients with moderate to severe psoriasis often require treatment with systemic therapies which can be either oral medications or injectable biologics. Few oral treatments are available today and new drugs with improved efficacy and safety are needed. The biologic treatments can be very effective, but their use is limited by high costs, patient preference against injections, and requirements for monitoring by the treating physician.


1)      Silverberg J.I. et al., Pharmacology of orismilast, a potent and selective PDE4 inhibitor, JEADV 2022: https://onlinelibrary.wiley.com/doi/10.1111/jdv.18818  & Warren R.B. et al., Efficacy and safety in moderate-severe psoriasis and development of modified release tablets, JEADV 2022: https://onlinelibrary.wiley.com/doi/10.1111/jdv.18812

2)      US data: Armstrong et al. Psoriasis Prevalence in Adults in the United States. JAMA Dermatol. 2021: https://pubmed.ncbi.nlm.nih.gov/34190957/

UK, Germany, France, Italy, Spain and Japan data: Decision Resources Group Psoriasis Report 2020.

3)      Armstrong AW and Read C. Pathophysiology, Clinical Presentation, and Treatment of Psoriasis: A Review. JAMA 2020: https://pubmed.ncbi.nlm.nih.gov/32427307/

4)      Nast A. et al. EuroGuiDerm guideline for the systemic treatment of psoriasis vulgaris, February 2022: https://guidelines.edf.one/guidelines/psoriasis-guideline



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, multi-asset, clinical stage, pharmaceutical development company focused on immunology and infectious diseases. The company is currently working with two complementary chemistry classes, spanning immunology and microbiology with multiple candidates in clinical development. UNION is headquartered in Hellerup, Denmark, and led by an international team combining 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