Safety of ON 01910.Na as a 3-day Infusion in Patients With Advanced Cancer

The primary objective of this study is to determine the largest dose of ON 01910.Na (rigosertib sodium) that can be given safely as a 3-day continuous infusion once every 2 weeks (2-week cycle) in patients with advanced cancer.

This was an open-label, single-center, dose-escalating Phase I study to determine the Dose-Limiting Toxicities (DLTs) and Recommended Phase 2 Dose (RPTD) of ON 01910.Na (rigosertib sodium) administered as a 3 day continuous intravenous (CIV) infusion every 2 weeks (2-week cycles) to up to 28 patients with advanced cancer (12 to 16 in the dose escalation phase and up to 12 additional patients in the dose confirmation phase). The dosing of rigosertib was based on body surface area (BSA), with a starting dose of 50 mg/m2/24 hour for 3 consecutive days. In the absence of toxicity after at least a 3-week observation period, rigosertib doses were escalated following a Fibonacci scheme with an initial accelerated dose-escalation phase in which 1-patient cohorts received rigosertib for 3 weeks until drug-related Grade 2 toxicity (according to Common Toxicity Criteria for Adverse Events \[CTCAE\] v.3), excluding alopecia, occurred, at which time 2 additional patients were added to subsequent cohorts. If none of the 3 patients in the cohort experienced DLTs, the dose was escalated by a half-Fibonacci step. If a DLT was seen in the first patient of a cohort, dosing went back a half-step. The next dose level occurred if no DLT was reported in the 3 patients or if no more than 1 DLT occurred in an expanded cohort of 6 patients. If a DLT was seen in 1 of the 3 patients, 3 additional patients were enrolled in the cohort. If DLTs were seen in 2 of 6 patients in a cohort, dose escalation was stopped. Once the maximum administered dose (MAD) was attained and the RPTD was determined, the dose escalation phase was considered complete. Up to 12 additional patients with histologically confirmed malignant tumors were tested at the RPTD dose to confirm its appropriateness. Secondary objectives were to determine the qualitative and quantitative toxicity and reversibility of toxicity of rigosertib administered in this fashion; to investigate the clinical pharmacology of rigosertib when administered in this fashion, including plasma pharmacokinetics at each dose level; to confirm the appropriateness of the RPTD; to document any observed antitumor activity of rigosertib; and, to evaluate the biological effect of rigosertib in biomarkers in serum and/or peripheral blood mononuclear cells.