JAK inhibition in the treatment of alopecia areata - a promising new dawn?

Introduction: Alopecia areata (AA) is a T-cell-mediated disease which produces circular patches of non-scarring hair loss and nail dystrophy. Current treatment options for AA are limited and often yield unsatisfactory results. Pharmacologic inhibition of the Janus kinase (JAK) enzyme family is regrowing hair and reversing nail dystrophy in a number of patients with hitherto refractory AA. The six JAK inhibitors which have been successful in treating AA are tofacitinib, ruxolitinib, baricitinib, CTP-543, PF-06651600 and PF-06700841. Areas covered: This review reports randomized-controlled trials, open-label trials, case series and case reports published in the literature to date and describes the epidemiology and pathophysiology of AA, the mechanism of action of JAK inhibitors and the adverse effects identified. Electronic searches were performed using Medline Ovid, PubMed, Embase, Cochrane Library and Evidence-Based Medicine Reviews. Expert opinion: The discovery of JAK inhibition represents a major breakthrough in the treatment of AA. Positive results in early phase 1 and phase 2 clinical trials have enabled the commencement of phase 3 clinical trials and there is now a growing sense of optimism among patients with long-standing, treatment-refractory AA. Further work is required to determine the optimal dose and treatment duration and whether maintenance therapy is universally required.