Rapid response of lichen planus to baricitinib associated with suppression of cytotoxic CXCL13+ CD8+ T-cells.

Background: Cutaneous lichen planus (LP) is a recalcitrant, difficult-to-treat, inflammatory skin disease characterized by pruritic, flat-topped, violaceous papules on the skin. Baricitinib is an oral Janus kinase (JAK) 1/2 inhibitor that interrupts the signaling pathway of interferon gamma (IFN)-γ, a cytokine implicated in the pathogenesis of LP.

Methods: In this phase II trial, twelve patients with cutaneous LP received baricitinib 2 mg daily for 16 weeks, accompanied by in-depth spatial, single-cell, and bulk transcriptomic profiling of pre- and post-treatment samples.

Results: An early and sustained clinical response was seen, with 83.3% of patients responsive at week 16. Our molecular data identified a unique, oligoclonal IFN-γ, CD8+, CXCL13+ cytotoxic T-cell population in LP skin and demonstrated a rapid decrease in IFN signature within 2 weeks of treatment, most prominently in the basal layer of the epidermis.

Conclusion: This study demonstrates the efficacy and molecular mechanisms of JAK inhibition in LP.

Trial registration: NCT05188521.ROLE OF FUNDING SOURCE. Eli Lilly, Appignani Benefactor Funds, 5P30AR075043, Mayo Clinic Clinical Trials Stimulus Funds.