Tofacitinib as a Novel Therapeutic Option for Pemphigus Vulgaris: A Case Report and Mechanistic Insights.

Pemphigus vulgaris (PV), a life-threatening autoimmune blistering disorder mediated by pathogenic anti-desmoglein antibodies, manifests clinically with extensive cutaneous and mucosal vesicles, bullae, and erosions. While corticosteroids remain first-line therapy, a substantial subset of patients develop refractory disease requiring advanced therapies. Tofacitinib, an oral Janus kinase (JAK) 1/3 inhibitor, demonstrates broad immunomodulatory effects through interference with cytokine signaling pathways. We report the case of a 50-year-old male with recalcitrant PV who achieved sustained remission following adjunctive tofacitinib therapy. Combination therapy with tofacitinib (5 mg twice daily) and prednisone (60 mg/day) enabled successful corticosteroids withdrawal within 5 months, achieving complete clinical remission (PDAI=0) and serological improvement (Dsg1/Dsg3 antibodies reduced by 64.5%/75.8%). Longitudinal immunohistochemistry (IHC) revealed attenuated phospho-STAT3 and phospho-STAT6 in post-treatment lesional skin compared to baseline. Proteomic profiling of PV lesions (n=3) versus healthy controls (n=3) identified 198 differentially expressed proteins (fold change >1.5, p<0.05), with KEGG pathway analysis revealing predominant enrichment in JAK-STAT signaling, IL-17-mediated inflammation, and lymphocyte differentiation pathways. Independent validation in an expanded cohort (5 PV vs 5 controls) confirmed constitutive JAK-STAT hyperactivation: phospho-STAT3 (7.2±1.64 vs 1±0, p<0.001) and phospho-STAT6 (9.6±1.34 vs 1.2±0.45, p<0.001) were markedly elevated in untreated PV lesions. These findings posit tofacitinib as a promising steroid-sparing agent in PV management, potentially through multimodal inhibition of pathogenic cytokine networks. Large-scale randomized controlled trials are warranted to validate these observations.