Generation and Clinical Application of Gene-Modified Autologous Epidermal Sheets in Netherton Syndrome:Lessons Learned from a Phase 1 Trial

Netherton Syndrome (NS) is a rare autosomal recessive skin disorder caused by mutations in SPINK5. It is a debilitating condition with notable mortality in the early years of life. There is no curative treatment. We undertook a non-randomized, open-label, feasibility and safety study using autologous keratinocytes transduced with a lentiviral vector encoding SPINK5 under the control of the human involucrin promoter. Six NS subjects were recruited and gene-modified epithelial sheets were successfully generated in three out of five subjects. The sheets exhibited expression of correctly sized LEKTI protein after modification. One subject was grafted with a 20cm2 gene-modified graft on the left anterior thigh without any adverse complications and was monitored by serial sampling for 12 months. Recovery within the graft area were compared against an area outside by morphology, pro-viral copy number and expression of the SPINK5 encoded protein, LEKTI, and its down-stream target kallikrein 5, which exhibited transient functional correction. The study confirmed the feasibility of generating lentiviral gene-modified epidermal sheets for inherited skin diseases such as NS, but sustained LEKTI expression is likely to require the identification, targeting and engraftment of long-lived keratinocyte stem cell populations for durable therapeutic effects. Important learning points for the application of gene modified epidermal sheets are discussed

Safety and early efficacy outcomes for lentiviral fibroblast gene therapy in recessive dystrophic epidermolysis bullosa

BACKGROUND. Recessive dystrophic epidermolysis bullosa (RDEB) is a severe form of skin fragility disorder due to mutations in COL7A1 encoding basement membrane type VII collagen (C7), the main constituent of anchoring fibrils (AFs) in skin. We developed a self-inactivating lentiviral platform encoding a codon-optimized COL7A1 cDNA under the control of a human phosphoglycerate kinase promoter for phase I evaluation. METHODS. In this single-center, open-label phase I trial, 4 adults with RDEB each received 3 intradermal injections (~1 × 106 cells/cm2 of intact skin) of COL7A1-modified autologous fibroblasts and were followed up for 12 months. The primary outcome was safety, including autoimmune reactions against recombinant C7. Secondary outcomes included C7 expression, AF morphology, and presence of transgene in the injected skin. RESULTS. Gene-modified fibroblasts were well tolerated, without serious adverse reactions or autoimmune reactions against recombinant C7. Regarding efficacy, there was a significant (P < 0.05) 1.26-fold to 26.10-fold increase in C7 mean fluorescence intensity in the injected skin compared with noninjected skin in 3 of 4 subjects, with a sustained increase up to 12 months in 2 of 4 subjects. The presence of transgene (codon-optimized COL7A1 cDNA) was demonstrated in the injected skin at month 12 in 1 subject, but no new mature AFs were detected. CONCLUSION. To our knowledge, this is the first human study demonstrating safety and potential efficacy of lentiviral fibroblast gene therapy with the presence of COL7A1 transgene and subsequent C7 restoration in vivo in treated skin at 1 year after gene therapy. These data provide a rationale for phase II studies for further clinical evaluation.Funding was received from Cure EB (previously known as Sohana Research Fund) in association with the Dystrophic Epidermolysis Bullosa Research Association (DEBRA, UK). The study was supported by the UK NIHR Biomedical Research Centres at Great Ormond Street, Guy’s and St Thomas’ NHS Foundation Trust, and King’s College London. The NIHR also supported WQ (RP2014). SML received a short-exchange fellowship from Fondation René Touraine to undertake the C7 ELISPOT assay at the Imagine Institute as part of this study. We are thankful to the EB clinical team, including EB specialist nurses at Guy’s and St Thomas’ NHS Foundation Trust and staff at the Clinical Research Facility, Guy’s Hospital, London, United Kingdom. Our special thanks go to all the patients for their time, enthusiasm, and dedicated commitment to participating in the trial and granting permission to publish this information