Pfizer’s JAK1 Inhibitor Impresses in Phase 3 Atopic Dermatitis Trial

On November 11th, Pfizer announced the results for their Phase 3 JADE REGIMEN study, which aimed to determine the efficacy of Abrocitinib in patients with moderate to acute atopic dermatitis (AD). Treatment with Abrocitinib resulted in an Investigator’s Global Assessment (IGA) response of clear or almost clear, defined as no inflammatory signs or just perceptible erythema, for over 60% percent of treated patients. Crucially, most of these patients continued to respond to the treatment for the full duration of the trial, so they did not develop resistance to the treatment.

Atopic dermatitis is a chronic inflammatory disease characterized by red scaly patches of skin and severe itching. In the USA, around 9.6 million children and 16.5 million adults suffer from AD. Worldwide, AD affects up to 10% of adults and 20% of children, with the rate in the case increasing since the late 1990s.

There is no available cure for AD; however, oral or topical corticosteroids can reduce the inflammation and control itchiness in some patients. Other medications include calcineurin inhibitors, and the newly FDA approved IL-4 receptor antagonist Dupilumab. Not all patients respond to these medications, and Dupilumab must be injected. For this reason, new orally available effective therapeutic options are necessary.

JADE REGIMEN Study

The JADE REGIMEN was a randomized, responder-enriched, double-blind, placebo-controlled, Phase 3 withdrawal trial. The trials took place over 52 weeks. First, all patients received 200mg of Abrocitinib for 12 weeks to determine the responder status. Of the 1233 patients, 64.6% responded to Abrocitinib, which was a higher percentage than expected. These patients were assigned to one of three groups, 100mg, 200mg Abrocitinib, or placebo for a 40-week, double-blind, maintenance period. The results showed that patients in the two Abrocitinib groups were less likely to experience a flare, with 81.1% and 57.4% of patients not experiencing a flare, versus 19.1 % in placebo. Furthermore, no new safety signals were observed during the study.

“Atopic dermatitis brings a lot of uncertainty and disruption to daily life, and the unpredictability of flares can make treating and managing the disease complex and frustrating,” said Michael Corbo, Ph.D., Chief Development Officer, Inflammation & Immunology, Pfizer Global Product Development. “These latest results from our Phase 3 clinical trial program shed light on the potential Abrocitinib, if approved, could have to prevent troublesome flares in patients.”

JAK Inhibitors Against AD

Abrocitinib is an orally available small molecule that inhibits the Janus Kinase (JAK) 1 protein. Inhibition of this protein modulates the levels of multiple inflammatory molecules thought to be involved in the pathology of AD. Pfizer has received Priority Review designation by the U.S. Food and Drug Administration and Marketing Authorization Application by the European Medicines Agency for Abrocitinib. However, this is not the only JAK inhibitor currently being tested for the treatment of AD.

Currently, there are other JAK inhibitors in Phase 3 clinical trials. A few examples are Upadacitinib, developed by AbbVie, and Baricitinib, co-developed by Olumiant and Elli Lilly. Furthermore, Incyte, in collaboration with Pfizer, is testing a second JAK inhibitor, Ruxolitinib, for the treatment of AD. Not far behind is the pan-JAK inhibitor Delgocitinib, currently in Phase 2a clinical trials, which was developed by drug manufacturer Torri and Japan tobacco.

By Daniel Ojeda, Ph.D.

Related Article: Pfizer Announces Positive Top-Line Results for JAK Inhibitor in Ankylosing Spondylitis Trial

References

1. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-announces-positive-results-fifth-phase-3-trial
2. https://www.mayoclinic.org/diseases-conditions/atopic-dermatitis-eczema/symptoms-causes/syc-20353273
3. https://nationaleczema.org/research/eczema-facts/
4. https://www.mayoclinic.org/diseases-conditions/atopic-dermatitis-eczema/diagnosis-treatment/drc-20353279
5. https://pubmed.ncbi.nlm.nih.gov/29471919/
6. https://practicaldermatology.com/articles/2020-apr/phase-2-and-3-trials-of-jak-inhibitors-for-atopic-dermatitis-a-review

Author

Daniel Ojeda