PTC596 in Patients With Advanced Solid Tumors

This is a Phase 1, open-label, first-in-human, safety and pharmacokinetic (PK) study of PTC596 in patients with advanced cancer. A variation of the traditional 3+3 dose escalation design will be employed. PTC596 will be administered orally on a twice a week (biw) schedule. Each 4-week period of drug administration will be considered one cycle. The objective of the study will be to determine the recommended Phase 2 dose (RP2D) and to determine preliminary proof of mechanism of action. Collectively, data from the Good Laboratory Practice (GLP) and non-GLP studies indicate that 40 mg/kg biw is approximately the severely toxic dose in 10% of animals (STD 10). Therefore, the starting dose in this study will be calculated as one-tenth of the human equivalent dose (HED) of 40 mg/kg biw in rats, which is 0.65 mg/kg biw. In this study, escalating dose levels will be evaluated to determine the RP2D. Three patients will be enrolled at the starting dose level (0.65 mg/kg biw); if 1 of the 3 patients experiences a dose-limiting toxicity (DLT), an additional 3 patients will be enrolled at the same dose level. Thus, 3 to 6 patients will receive the starting dose level of 0.65 mg/kg. Dose escalation will continue until the occurrence of DLT in ≥2/6 patients at a given dose level. Dose escalation will occur in approximately 100% increments until Grade ≥2, first-cycle toxicity is seen in at least 2 patients across all dose levels, after which dose escalation will occur in smaller (50% or 33%) increments.