A Double-blind, Randomized, Intra-subject Placebo-controlled, Multicenter, Multiple Dose Study, Evaluating Safety, Proof of Mechanism, Preliminary Efficacy and Systemic Exposure in Subjects With Confirmed DDEB or RDEB Diagnosis With One or More Pathogenic Mutations in Exon 73 in the COL7A1 Gene

This clinical trial will evaluate the safety and tolerability, proof of mechanism, systemic exposure and preliminary efficacy following topical application of QR-313 to subjects with confirmed DDEB or RDEB with one or more pathogenic mutations in exon 73 in the COL7A1 gene. Up to two Target Wound Areas (TWAs) per subject will be selected and randomized. Each TWA will be treated with IMP for 8 weeks, either QR-313 or matching placebo. All subjects will continue to be followed up for 8 weeks post last dose. Subjects will be monitored through home visits and site visits. An imaging system will be used to assess the target wound at all home and study site visits. QR-313 is a 21-nucleotide antisense oligonucleotide (AON) designed to hybridize to a specific sequence in the COL7A1 pre-messengerRNA (pre-mRNA).