P100 Topical Janus kinase inhibitors for lichenoid disorders: a systematic review of the current evidence landscape

Abstract

Lichenoid disorders such as cutaneous lichen planus (LP), lichen planopilaris (LPP) and frontal fibrosing alopecia (FFA) involve interferon–Janus kinase (JAK)–signal transducer and activator of transcription signalling. Topical JAK inhibitors target this pathway with limited systemic exposure, but current evidence is limited. The aim of this study was to map and critically appraise clinical, safety and mechanistic evidence for topically administered JAK inhibitors across cutaneous lichenoid phenotypes. We performed a PRISMA-guided systematic review (PROSPERO CRD420251155683), searching MEDLINE, Embase, Scopus and clinical trial registries to 1 November 2025. We included studies of topical JAK inhibitors for cutaneous LP, LPP/FFA, lichen planus pigmentosus (LPPig) or nail LP with clinical or molecular outcomes. One reviewer screened and extracted data and a second verified the extractions. Risk of bias was assessed and certainty of evidence was graded using GRADE. Thirteen studies (14 reports) with 118 patients were included; approximately 100 had scarring alopecia. In FFA, a phase IIa double-blind, vehicle-controlled trial of delgocitinib 2% cream (n = 30) met its molecular primary endpoint and improved clinical scores, including Frontal Fibrosing Alopecia Severity Score, compared with vehicle. Two scalp cohorts using tofacitinib 2% (n = 41) and ruxolitinib 1.5% (n = 20) creams reported Lichen Planopilaris Activity Index reductions of about 48% and 34%, respectively. For cutaneous LP (n = 12), open-label ruxolitinib cream improved modified Composite Assessment of Index Lesion Severity and symptoms with lesional downregulation of interferon-stimulated gene in responders. Evidence for LPPig (n = 2) and nail LP (n = 4) consisted of case-level reports showing clinical improvement. Topical JAK inhibitors were well tolerated, with infrequent local irritation or acne and no treatment-related serious adverse events. Certainty of clinical efficacy was low for scarring alopecia and very low for other phenotypes; certainty for mechanistic target engagement was low. Topical JAK inhibitors appear to be promising, well-tolerated, steroid-sparing adjuncts for refractory lichenoid disease, particularly LPP/FFA. However, the small, heterogeneous evidence base and low certainty mean that well-designed, vehicle-controlled trials with phenotype-specific endpoints and embedded mechanistic correlates are required before routine use can be recommended.

P101Abstract withdrawn.