Significant improvement with ivarmacitinib after suboptimal response to tofacitinib in severe alopecia areata: a case report and literature review.

Alopecia areata (AA) is a chronic, immune-mediated hair loss disorder, in which the JAK-STAT signaling pathway plays an important pathogenic role. Available agents for AA include minoxidil, corticosteroids, immunosuppressants and Janus kinase (JAK) inhibitors, among others. For adults with severe AA, JAK inhibitors have emerged as cornerstone systemic treatments, but the responses to them are variable. Ivarmacitinib is a novel and highly selective JAK1 inhibitor, which has been approved for AA in China recently with little real-world evidence. We present a case of a patient with severe AA who achieved significant improvement with ivarmacitinib after suboptimal response to tofacitinib, and review previous studies on switching therapy between different JAK inhibitors for AA. This case suggests that ivarmacitinib is a viable alternative for tofacitinib-refractory AA, possibly due to its higher JAK1 selectivity. Further studies are required to define ivarmacitinib's optimal position in AA treatment algorithm, and to elucidate underlying mechanisms behind JAK inhibitors, which is essential for more personalized and targeted therapy for severe AA.