New JAK inhibitors for the treatment of psoriasis and psoriatic arthritis

Psoriasis is a common inflammatory skin disease that can be associated with various pathological conditions among which arthritis is a frequent comorbidity. Based on the current pathogenetic model, development of psoriasis is mainly driven by the IL-23/IL-17Aaxis. Though the therapeutic armamentarium is expanding in the latest years, new therapies are needed because of the lack or loss of response or intolerance/contraindication to the currently approved drugs. The most recently developed drugs for the treatment of psoriasis and psoriatic arthritis specifically target cytokines, cytokine receptors, and intracellular signaling transducers that are involved in the pathogenesis of psoriasis. Janus kinase (JAK) pathway transduces signals of multiple cytokines, such as TNF-α, IL-23, IL-12, IFN, IL-6, IL-17, that have resulted crucial in the induction and maintenance of psoriasis inflammation. Thereby, JAK-1, JAK-3, TYK-2 belonging to the JAK family, have been identified as valid therapeutic targets in the treatment of psoriasis. Nowadays, different JAK inhibitors have been investigated in clinical trials showing promising results in terms of efficacy and safety. In this review, we systematically collected publications and data related to JAK inhibitors used in psoriasis and psoriatic arthritis providing the state-of-the-art on this new class of molecules in the treatment of these diseases.