Rigosertib in Patients With Recessive Dystrophic Epidermolysis Bullosa Associated SCC

PRIMARY OBJECTIVES: I. To estimate the anti-tumor activity of oral or IV rigosertib in RDEB patients with advanced SCC that have failed prior standard of care, by determining the overall response rate (ORR) which is defined as the proportion of patients who achieve either a CR or a PR by RECIST v1.1 II. To evaluate the safety and tolerability of oral rigosertib administered either orally daily three weeks on, one week off or as 72h CIV infusions on day 1-3 of a two week-cycle for 8 cycles and then on day 1-3 of a 4 week cycle thereafter SECONDARY OBJECTIVES: I. Assess impact on quality of life (QoL) II. Biomarker analysis (to include markers of PI3K/Akt and PLK1 pathways) performed on all archival tissue from all patients EXPLORATORY OBJECTIVE: I. Exome sequencing of patient tumors before, during, and after treatment OUTLINE: Patients will receive rigosertib sodium as either oral capsules or IV infusion. Mode of application is determined by the responsible investigator depending on participant's needs, general condition, and possibility of ambulatory treatment or need of hospitalization. Patients will take oral rigosertib continuously for a total of three weeks of a four-week cycle (three weeks on, one week off drug). For IV treatment, patients will receive rigosertib IV administered as a 72-hr continuous infusion on Days 1, 2 and 3 of a 2-week cycle for the first eight 2-week cycles, then on Days 1, 2 and 3 of a 4-week cycle thereafter. Patients will receive treatment over a 52 week period. After completion of study treatment, patients are followed periodically every 3 months over a 12 month period.