Identification of Rigosertib for the Treatment of Recessive Dystrophic Epidermolysis Bullosa–Associated Squamous Cell Carcinoma

PURPOSE: Squamous cell carcinoma (SCC) of the skin is the leading cause of death in patients with the severe generalized form of the genetic disease recessive dystrophic epidermolysis bullosa (RDEB). Although emerging data are identifying why patients suffer this fatal complication, therapies for treatment of RDEB SCC are in urgent need. EXPERIMENTAL DESIGN: We previously identified polo-like kinase 1 (PLK1) as a therapeutic target in skin SCC, including RDEB SCC. Here, we undertake a screen of 6 compounds originally designated as PLK1 inhibitors, and detail the efficacy of the lead compound, the multipathway allosteric inhibitor ON-01910, for targeting RDEB SCC in vitro and in vivo. RESULTS: ON-01910 (or rigosertib) exhibited significant specificity for RDEB SCC: in culture rigosertib induced apoptosis in 10 of 10 RDEB SCC keratinocyte populations while only slowing the growth of normal primary skin cells at doses 2 orders of magnitude higher. Furthermore, rigosertib significantly inhibited the growth of two RDEB SCC in murine xenograft studies with no apparent toxicity. Mechanistically, rigosertib has been shown to inhibit multiple signaling pathways. Comparison of PLK1 siRNA with MEK inhibition, AKT inhibition, and the microtubule-disrupting agent vinblastine in RDEB SCC shows that only PLK1 reduction exhibits a similar sensitivity profile to rigosertib. CONCLUSIONS: These data support a “first in RDEB” phase II clinical trial of rigosertib to assess tumor targeting in patients with late stage, metastatic, and/or unresectable SCC

Management of chronic wounds in patients with dystrophic epidermolysis bullosa: challenges and solutions

Ellie Rashidghamat,1 Jemima E Mellerio,1,2 1St John’s Institute of Dermatology, King’s College London, 2St John’s Institute of Dermatology, Guy’s and St Thomas’ NHS Foundation Trust, London, UK Abstract: Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of severe inherited blistering diseases that affects 500,000 individuals worldwide. Clinically, individuals with EB have fragile skin and are susceptible to blistering following minimal trauma and show involvement of mucus membrane and other organs in some subtypes. Dystrophic EB (DEB) is divided into 2 major types depending on the inheritance pattern: recessive DEB (RDEB) and dominant DEB (DDEB). RDEB tends to be at the more severe end of the clinical spectrum and has a prevalence of 8 per 1 million of the population, accounting for approximately 5% of all cases of EB. RDEB is caused by loss-of-function mutations in the type VII collagen gene, COL7A1, which leads to reduced or absent type VII collagen (C7) and structurally defective anchoring fibrils at the dermal-epidermal junction. In this review, we will discuss the management of chronic wounds in individuals with DEB, highlighting the changes to practice and the novel therapies that may offer a solution to this debilitating and complex problem which is one of the greatest sources of morbidity in this disease. Keywords: epidermolysis bullosa, recessive dystrophic, dominant dystrophic, wound healin

Transcriptomic profiling of recessive dystrophic epidermolysis bullosa wounded skin highlights drug repurposing opportunities to improve wound healing

Chronic wounds present a major disease burden in people with recessive dystrophic epidermolysis bullosa (RDEB), an inherited blistering skin disorder caused by mutations in COL7A1 encoding type VII collagen, the major component of anchoring fibrils at the dermal-epidermal junction. Treatment of RDEB wounds is mostly symptomatic, and there is considerable unmet need in trying to improve and accelerate wound healing. In this study, we defined transcriptomic profiles and gene pathways in RDEB wounds and compared these to intact skin in RDEB and healthy control subjects. We then used a reverse transcriptomics approach to discover drugs or compounds, which might restore RDEB wound profiles towards intact skin. Differential expression analysis identified >2000 differences between RDEB wounds and intact skin, with RDEB wounds displaying aberrant cytokine-cytokine interactions, Toll-like receptor signalling, and JAK-STAT signalling pathways. In-silico prediction for compounds that reverse gene expression signatures highlighted methotrexate as a leading candidate. Overall, this study provides insight into the molecular profiles of RDEB wounds and underscores the possible clinical value of reverse transcriptomics data analysis in RDEB, and the potential of this approach in discovering or repurposing drugs for other diseases