Phase 1/2a clinical trial of gene-corrected autologous cell therapy for recessive dystrophic epidermolysis bullosa

Abstract

BACKGROUNDRecessive dystrophic epidermolysis bullosa (RDEB) patients have mutations in the COL7A1 gene and thus lack functional type VII collagen (C7) protein; they have marked skin fragility and blistering. This single-center phase 1/2a open-label study evaluated the long-term efficacy, safety, and patient-reported outcomes in RDEB patients treated with gene-corrected autologous cell therapy.METHODSAutologous keratinocytes were isolated from participant skin biopsies. Epidermal sheets were prepared from cells transduced with a retrovirus carrying the full-length human COL7A1 gene. These gene-corrected autologous epidermal sheets measured 5 × 7 cm (35 cm2) and were transplanted onto 6 wound sites in each of 7 adult participants (n = 42 sites total) from 2013 to 2017. Participants were followed for 2 to 5 years.RESULTSNo participants experienced any serious related adverse events. Wound healing of 50% or greater by Investigator Global Assessment was present in 95% (36 of 38) of treated wounds versus 0% (0 of 6) of untreated control wounds at 6 months (P < 0.0001). At year 1, 68% (26 of 38) of treated wounds had 50% or greater healing compared with 17% (1 of 6) of control wounds (P = 0.025). At year 2, 71% (27 of 38) of treated wounds had 50% or greater healing compared with 17% (1 of 6) of control wounds (P = 0.019).CONCLUSIONC7 expression persisted up to 2 years after treatment in 2 participants. Treated wounds with 50% or greater healing demonstrated improvement in patient-reported pain, itch, and wound durability. This study provides additional data to support the clinically meaningful benefit of treating chronic RDEB wounds with ex vivo, C7 gene-corrected autologous cell therapy. This approach was safe and promoted wound healing that was associated with improved patient-reported outcomes.TRIAL REGISTRATIONClinicaltrials.gov identifier: NCT01263379.FUNDINGEpidermolysis Bullosa Research Partnership, Epidermolysis Bullosa Medical Research Foundation, NIH R01 AR055914, Office of Research and Development at the Palo Alto Veteran's Affairs Medical Center, and the Dermatology Foundation.

Keywords: Dermatology; Gene therapy; Genetic diseases.

Conflict of interest statement

Conflict of interest: The authors have declared that no conflict of interest exists.

Figures

Figure 1. Representative clinical photographs of C7 gene–corrected cell therapy in participants.

(A) Participant 7, C7 gene–corrected treated sites A, C, and D, upper back. (B) Participant 5, untreated control wound, right antecubital fossa. (C) Participant 5, C7 gene–corrected treated sites A and B, left upper arm. Photographs of RDEB wounds at baseline and at designated time points after treatment. In A and C, purple marker outlines gene-corrected autologous cellular sheet edges; each treated wound is denoted with a letter. Participant 7’s sites A, C, and D demonstrate persistent healing at 2 years after treatment (A). Participant 5’s sites A and B (C) demonstrated wound healing at months 3 and 6. Participant 5’s untreated control wound (B) did not close during the measured time points.

Figure 2. Clinical response of wound healing as assessed by investigator global assessment (IGA).

Percentage of wound healing based on clinical assessment by IGA at designated time points. A green box indicates ≥75% wound healing, yellow box indicates 50%–74% wound healing, and a red box indicates ≤49% wound healing. R, right; L, left. Blank white spaces denote prospective dates.

Figure 3. Wound healing in treated and untreated wounds.

Summary of treated wounds and untreated control wounds that achieved ≥50% wound healing (A) and wounds that achieved ≥75% wound healing (B) at designated time points after treatment, as assessed by Investigator Global Assessment. Black bars represent treated sites; light gray bars represent untreated control wounds.

Figure 4. Assessment of molecular correction of C7 in serial biopsies of treated sites (participants 4 and 6).

Skin biopsies obtained at indicated time points demonstrate presence of C7 at the dermal-epidermal basement membrane zone. (A and B) Immuno-electron microscopy (IEM) and immunofluorescence (IF), respectively, for participant 6. (C and D) IEM and IF, respectively, for participant 4. (A and C) IEM tissue sections from skin biopsies were labeled en bloc with anti-C7 LH24 monoclonal antibody, followed by anti–mouse IgM–conjugated immunogold particles (black dots, arrows), which decorate anchoring fibrils (AFs). Baseline demonstrates few AFs present for participant 4. Note that the specimen was split at baseline for participant 6 and thus we cannot comment on presence or absence of AFs. Participant 6 at year 1 and participant 4 at year 2 demonstrate an increased presence of AFs. Scale bars: 500 nm. (B and D) IF from skin biopsies. White arrows indicate the location of the dermal-epidermal junction. Anti-C7 LH24 monoclonal antibody was used to detect the NC2 domain of C7 (green). Linear green staining at the dermal-epidermal junction indicates the presence of C7, which is absent at baseline but observed at 2 years.