Hellerup, Denmark, November 29, 2023 – UNION therapeutics A/S (UNION), a privately-held, clinical stage, pharmaceutical development company focused on immunology, today announced publication of a paper highlighting the differentiated features of the emerging class of selective PDE4B/D inhibitors in the peer-reviewed journal of Dermatology and Therapy.

The paper co-authored with leading researchers within immune dermatology describes the emerging class of selective PDE4B/D inhibitors. PDE4 is a well-established mechanism of action with a well-documented safety profile, and with clinical and commercial success for the treatment of several different chronic inflammatory diseases. However, the major challenge with currently available pan-PDE4 inhibitors has been modest clinical efficacy.1) 

Recent research has identified four subtypes of PDE4 inhibition labelled A-D. This breakthrough has enabled further research into immune cells, where it has been established that primarily PDE4 B and D subtypes are highly expressed. This has helped the development of more potent PDE4 B/D selective inhibitors which may drive higher efficacy in treating immune diseases compared to previously approved pan-PDE4 inhibitors. The mechanism of action also has the potential to positively impact co-morbidities that are associated with chronic inflammatory skin diseases, including cardiometabolic disease.


Andrew Blauvelt, MD, dermatologist and investigator at the Oregon Medical Research Center, Portland, US, author of new article on PDE4-inhibitors said:

A new class of selective PDE4B/D inhibitors is emerging, with improved potency and potential to offer novel oral treatments in several inflammatory diseases. This review of current knowledge of PDE4 subtypes is highly relevant in a treatment landscape where safety, efficacy, and impact on co-morbidities are key aspects to treatment.

Morten Sommer, Chief Scientific Officer of UNION therapeutics said:

“Our understanding of PDE4-inhibition dramatically improved in recent years, highlighting the importance of selectively inhibiting PDE4B/D subtypes. These insights have guided us in the development of orismilast towards unlocking the potential of PDE4B/D inhibitors across immunology to the benefit of patients and caregivers.”


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.3)

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

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

3)       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, clinical stage, pharmaceutical development company focused on immunology. 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