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

Inclusion Criteria:

   1. Male or female, ≥ 4 years of age at Screening with a clinical diagnosis of DDEB or
   RDEB and at least one pathogenic mutation in exon 73 of the COL7A1 gene.

   2. Have at least one TWA, ie, a skin area of 7 x 7 cm that ishows no signs of local
   infection, and contains a target wound that is either new or shows dynamic wound
   healing and complies to the following additional criteria:

      1. surface area of the target wound ranging from 5 to 30 cm2, located centrally in
      the selected 7 x 7 cm TWA.

      2. exposed sub-epidermal tissue to allow absorption of the IMP.

      3. no suspicion of current squamous cell carcinoma (SCC) upon visual inspection.

Exclusion Criteria:

   1. Pregnant or breast-feeding female

   2. Hemoglobin level at Screening requiring transfusion. The subject may be rescreened
   when the condition is considered stable.

   3. Use of aminoglycosides, by any route of administration, except eye drops, 7 days or 5
   half-lives, whichever is longer, prior to Baseline visit.

   4. Untreated carcinoma of the TWA or history of carcinoma within 5 years prior to
   Screening, except adequately treated cutaneous squamous or basal cell carcinoma.

   5. Life expectancy less than 6 months, as assessed by the Investigator

   6. Current or known history of clinically significant hepatic or renal disease, that in
   the opinion of the Investigator, could impact subject safety or study participation.

   7. Treatment with any systemic immunomodulators, immunosuppressants or cytotoxic
   chemotherapy within 2 months prior to the Baseline visit.

   8. Use of any investigational drug or device within 28 days or 5 half-lives of the
   Baseline visit, whichever is longer, or plans to participate in another study of a
   drug or device during the study period. The washout of 5 half-lives does not apply to
   gene and cell therapy.

   9. Known hypersensitivity to oligonucleotide treatment or excipients of the IMP.

10. Bleeding disorder or condition requiring the use of anticoagulants to be confirmed by
   aPTT by local lab within 48 hours of first treatment.

11. Use of systemic or topical steroids within 1 month prior to the baseline visit
   (inhaled and ophthalmic drops of corticosteroids or low dose topical solution of
   budesonide for esophagial strictures may be allowed).