Drugs targeting epithelial–mesenchymal transition molecules for treatment of lichen planopilaris

Primary cicatricial alopecia (PCA), also known as scarring alopecia, comprises a diverse group of hair disorders that cause permanent destruction of the pilosebaceous unit, resulting in disappearance of the follicular ostia. Lichen planopilaris (LPP) is a subtype of primary lymphocytic cicatricial alopecia. There is an urgent need to identify novel molecules that successfully target specific pathogenic pathways in LPP to inhibit and reverse disease progression. Recent studies into LPP pathogenesis have discovered that follicular stem cells undergo epithelial-mesenchymal transition (EMT). We sought to identify drugs that target molecules involved in EMT to repurpose these drugs for treatment of LPP. We identified 8 molecules and 15 drugs that target these EMT molecules. Only four of these drugs (pioglitazone, tofacitinib, barcitinib and apremilast) have been reported in individual cases or case series of patients with LPP and controlled studies are missing. We describe each drug and mechanism of action target EMT in detail. Although previous studies have demonstrated the efficacy of EMT inhibitors in anticancer therapy, there are, to our knowledge, no studies using EMT-attenuating drugs for the treatment of LPP. The treatment molecules discussed in this paper provide a new platform for clinical studies and controlled trials in LPP.