A Sensitization-Free Dimethyl Fumarate Prodrug, Isosorbide Di-(Methyl Fumarate), Provides a Topical Treatment Candidate for Psoriasis

Dimethyl fumarate (DMF) is an effective oral treatment for psoriasis administered in Europe for nearly 60 years. However, its potential has been limited by contact dermatitis that prohibits topical application. This paper characterizes a DMF derivative, isosorbide DMF (IDMF), which was designed to have antipsoriatic effects without skin-sensitizing properties. We show that IDMF exhibits neither genotoxicity nor radiation sensitivity in skin fibroblasts and is nonirritating and nonsensitizing in animal models (rat, rabbit, guinea pig). Microarray analysis of cytokine-stimulated keratinocytes showed that IDMF represses the expression of genes specifically upregulated in psoriatic skin lesions but not those of other skin diseases. IDMF also downregulated genes induced by IL-17A and TNF in keratinocytes as well as predicted targets of NF-κB and the antidifferentiation noncoding RNA (i.e., ANCR). IDMF further stimulated the transcription of oxidative stress response genes (NQO1, GPX2, GSR) with stronger NRF2/ARE activation compared to DMF. Finally, IDMF reduced erythema and scaling while repressing the expression of immune response genes in psoriasiform lesions elicited by topical application of imiquimod in mice. These data show that IDMF exhibits antipsoriatic activity that is similar or improved compared with that exhibited by DMF, without the harsh skin-sensitizing effects that have prevented topical delivery of the parent molecule.