Clitocine for Translational Readthrough in Junctional Epidermolysis Bullosa

Junctional epidermolysis bullosa (JEB) caused by laminin-332 deficiency (JEB-LAM332) is a severe inherited skin disorder characterized by impaired dermal-epidermal adhesion, chronic wounds, and increased cancer susceptibility. The management of JEB-LAM332 is primarily symptomatic, focusing on wound care and general supportive measures; however, many therapeutic needs remain unmet. While gene and stem cell therapy has been effective in JEB-LAM332, it is not yet broadly available owing to its complexity and cost. Translational readthrough-inducing drugs (TRIDs) represent an alternative strategy for treating JEB-LAM332, given that most patients carry nonsense mutations in at least one allele of their LAMA3, LAMB3, or LAMC2 genes, with LAMB3 c.1903C>T, p.R635* (p.Arg635Ter) being the most common variant. To determine promising TRID candidates for developing readthrough therapy for JEB-LAM332 patients with LAMB3 mutations, we evaluated different classes of TRIDs and compared their efficacy against gentamicin. Erythromycin, TRID-C5 (aminoglycoside-based cocktail), artesunate and atazanavir (non-aminoglycosides, ribosomal protein RpL35 ligand) and clitocine (nucleoside analog) were tested in patient-derived keratinocytes carrying the LAMB3 nonsense variants, homozygous c.1903C>T (p.R635*) or compound heterozygous c.124C>T;c.1903C>T (p.R42*;p.R635*). We used a previously established screening platform for systematic testing of TRIDs, including immunoblotting, cell functional assays, and transcriptomics. We identified clitocine as the most potent compound for promoting translational readthrough, restoring laminin β3 chain expression and improving keratinocyte adhesion in JEB models. Clitocine treatment elicited dose- and mutation-dependent responses, while toxicity was observed at higher concentrations, particularly in normal keratinocytes. Although normal keratinocytes are not the intended therapeutic target, these findings highlight the importance of defining a therapeutic window and optimizing mutation-specific dosing. Overall, clitocine represents a potential candidate for the topical therapy of JEB-LAM332.