Emerging Systemic Treatments for Atopic Dermatitis

Atopic dermatitis (AD) is a chronic or chronically relapsing inflammatory skin disease which results from a complex, multifaceted interaction between environmental factors in genetically predisposed patients. Epidermal barrier impairment, alteration of the cutaneous microbiota, effect of external antigens, neurosensory dysfunction, and inflammatory and immune dysregulation all play a pivotal role in inducing and maintaining AD lesions. AD significantly impacts the patient's quality of life and general well-being and is often associated with anxiety and/or depressive symptoms. Classical treatment options include topical corticosteroids and calcineurin inhibitors, phototherapy, and systemic immunosuppression with oral corticosteroids, cyclosporine, methotrexate, and azathioprine in more severe cases. A turning point in facing AD was accomplished when the efficacy and safety of dupilumab, a monoclonal antibody targeting the interleukin (IL)-4 receptor α subunit, led to its approval for the treatment of moderate-to-severe or severe AD in children, adolescents, and adults. Subsequently, a more extensive understanding of AD etiology and pathogenesis has allowed the development of several topical and systemic novel therapy options. Most of these drugs are monoclonal antibodies which interfere with the type 2 inflammatory cascade, especially its key cytokines IL-4 and IL-13, or its downstream Janus kinase signaling pathway. However, considering the relevance of other subtypes of T helper (Th) cells, such as Th1 and Th22, and the important role of specific cytokines (IL-31) in generating pruritus, the horizon of potential therapeutic targets has widened extremely. In this review, we aim to present the most promising systemic agents currently under investigation and illustrate the most significant aspects of their efficacy, safety, and tolerability.