Onconova Therapeutics, Inc. announced that early preliminary data from an investigator-initiated Phase 2 open label trial of rigosertib monotherapy in advanced squamous cell carcinoma complicating recessive dystrophic epidermolysis bullosa (RDEB-associated SCC) were presented at the Austrian Society of Dermatology and Venerology Annual Conference 2021, which took place from November 25 ? 27, 2021. RDEB is an ultra-rare condition caused by a lack of type VII collagen protein expression. Type VII collagen protein is responsible for anchoring the skin?s inner layer to its outer layer, and its absence leads to extreme skin fragility and chronic wound formation in RDEB patients. Over time, many of these patients develop squamous cell carcinomas (SCCs) that typically arise in areas of chronic skin wounding and inflammation. Preclinical investigations demonstrated overexpression of polo like kinase 1 (PLK1) in RDEB-associated SCC tumor cells. These tumors show a highly aggressive, early metastasizing course, making them the primary cause of death for these patients, with a cumulative risk of death of 70% and 78.7% by age 45 and 55, respectively. These neoplasms show limited response rates of mostly short duration to conventional chemo- and radiotherapy as well as targeted therapy with epidermal growth factor and tyrosine kinase inhibitors. Data from the recent presentation are from a 24-year-old RDEB patient with a history of multiple, unresectable SCCs that were unresponsive to prior treatments including cemiplimab. Results showed that intravenously administered rigosertib had an acceptable safety profile and that the patient experienced sustained clinical and histological remission of all target lesions without signs of metastatic disease following 13 treatment cycles. The patient remains on study and the trial remains ongoing. The enrollment of additional patients is anticipated at sites in Salzburg, Austria; London, UK; and Philadelphia, Pennsylvania.