Patent landscape of molecular and cellular targeted therapies for recessive dystrophic epidermolysis bullosa

The potential of gene therapy for recessive dystrophic epidermolysis bullosa

Epidermolysis bullosa (EB) encompasses a heterogeneous group of inherited skin fragility disorders with mutations in genes encoding the basement membrane zone (BMZ) proteins that normally ensure dermal-epidermal integrity. Of the four main EB types, recessive dystrophic EB (RDEB), especially the severe variant, represents one of the most debilitating clinical entities with recurrent mucocutaneous blistering and ulceration leading to chronic wounds, infections, inflammation, scarring and ultimately cutaneous squamous cell carcinoma, which leads to premature death. Improved understanding of the molecular genetics of EB over the past three decades and advances in biotechnology has led to rapid progress in developing gene and cell-based regenerative therapies for EB. In particular, RDEB is at the vanguard of advances in human clinical trials of advanced therapeutics. Furthermore, the past decade has witnessed the emergence of a real collective, global effort involving academia and industry, supported by international EB patient organisations such as the Dystrophic Epidermolysis Bullosa Research Association (DEBRA), amongst others, to develop clinically relevant and marketable targeted therapeutics for EB. Thus, there is an increasing need for the practising dermatologist to become familiar with the concept of gene therapy, fundamental differences between various approaches and their human applications. This review explains the principles of different approaches of gene therapy; summarises its journey and discusses its current and future impact in RDEB.

Clinical trial of ABCB5+ mesenchymal stem cells for recessive dystrophic epidermolysis bullosa

BACKGROUND

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare, devastating, and life-threatening inherited skin fragility disorder that comes about due to a lack of functional type VII collagen, for which no effective therapy exists. ABCB5⁺ dermal mesenchymal stem cells (ABCB5⁺ MSCs) possess immunomodulatory, inflammation-dampening, and tissue-healing capacities. In a Col7a1^–/– mouse model of RDEB, treatment with ABCB5⁺ MSCs markedly extended the animals’ lifespans.

METHODS

In this international, multicentric, single-arm, phase I/IIa clinical trial, 16 patients (aged 4–36 years) enrolled into 4 age cohorts received 3 i.v. infusions of 2 × 10⁶ ABCB5⁺ MSCs/kg on days 0, 17, and 35. Patients were followed up for 12 weeks regarding efficacy and 12 months regarding safety.

RESULTS

At 12 weeks, statistically significant median (IQR) reductions in the Epidermolysis Bullosa Disease Activity and Scarring Index activity (EBDASI activity) score of 13.0% (2.9%–30%; P = 0.049) and the Instrument for Scoring Clinical Outcome of Research for Epidermolysis Bullosa clinician (iscorEB‑c) score of 18.2% (1.9%–39.8%; P = 0.037) were observed. Reductions in itch and pain numerical rating scale scores were greatest on day 35, amounting to 37.5% (0.0%–42.9%; P = 0.033) and 25.0% (–8.4% to 46.4%; P = 0.168), respectively. Three adverse events were considered related to the cell product: 1 mild lymphadenopathy and 2 hypersensitivity reactions. The latter 2 were serious but resolved without sequelae shortly after withdrawal of treatment.

CONCLUSION

This trial demonstrates good tolerability, manageable safety, and potential efficacy of i.v. ABCB5⁺ MSCs as a readily available disease-modifying therapy for RDEB and provides a rationale for further clinical evaluation.

TRIAL REGISTRATION

Clinicaltrials.gov NCT03529877; EudraCT 2018-001009-98.

FUNDING

The trial was sponsored by RHEACELL GmbH & Co. KG. Contributions by NYF and MHF to this work were supported by the NIH/National Eye Institute (NEI) grants RO1EY025794 and R24EY028767.

A systematic literature review of the disease burden in patients with recessive dystrophic epidermolysis bullosa

BACKGROUND/OBJECTIVE

Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic collagen disorder characterized by skin fragility leading to blistering, wounds, and scarring. There are currently no approved curative therapies. The objective of this manuscript is to provide a comprehensive literature review of the disease burden caused by RDEB.

METHODS

A systematic literature review was conducted in MEDLINE and Embase in accordance with PRISMA guidelines. Observational and interventional studies on the economic, clinical, or humanistic burden of RDEB were included.

RESULTS

Sixty-five studies were included in the review. Patients had considerable wound burden, with 60% reporting wounds covering more than 30% of their body. Increases in pain and itch were seen with larger wound size. Chronic wounds were larger and more painful than recurrent wounds. Commonly reported symptoms and complications included lesions and blistering, anemia, nail dystrophy and loss, milia, infections, musculoskeletal contractures, strictures or stenoses, constipation, malnutrition/nutritional problems, pseudosyndactyly, ocular manifestations, and dental caries. Many patients underwent esophageal dilation (29-74%; median dilations, 2-6) and gastrostomy tube placement (8-58%). In the severely affected population, risk of squamous cell carcinoma (SCC) was 76% and mortality from SCC reached 84% by age 40. Patients with RDEB experienced worsened quality of life (QOL), decreased functioning and social activities, and increased pain and itch when compared to other EB subtypes, other skin diseases, and the general population. Families of patients reported experiencing high rates of burden including financial burden (50-54%) and negative impact on private life (79%). Direct medical costs were high, though reported in few studies; annual payer-borne total medical costs in Ireland were $84,534 and annual patient-borne medical costs in Korea were $7392. Estimated annual US costs for wound dressings ranged from $4000 to $245,000. Patients spent considerable time changing dressings: often daily (13-54% of patients) with up to three hours per change (15-40%).

CONCLUSION

Patients with RDEB and their families/caregivers experience significant economic, humanistic, and clinical burden. Further research is needed to better understand the costs of disease, how the burden of disease changes over the patient lifetime and to better characterize QOL impact, and how RDEB compares with other chronic, debilitating disorders.