Safety and Pharmacology Study of SNX-5422 in Subjects With Refractory Hematological Malignancies

SNX-5422 is a prodrug for SNX-2112. Correlation has been observed between Hsp90 client protein level changes and functional effects in cells in in vitro studies of SNX-2112, supporting inhibition of Hsp90 as the mechanism of action for this compound. SNX-5422 has demonstrated significant antitumor activity in mouse xenograft models of human tumors, including breast (BT474, MX-1), colon (HT29), prostate (PC3), and melanoma (A375) with multiple oral dosing regimens. Pharmacokinetic (PK) studies in mice, rats, and dogs have shown high bioavailability of SNX-2112 following oral administration of SNX 5422. In mouse xenograft studies, SNX-2112 was selectively retained in tumor tissue compared with other tissues. This study will employ critical risk management features including the use of the NCI Common Terminology Criteria for Adverse Events (CTCAE) Version 4.03, which provides a scale for consistently grading the severity of AEs, toxicity criteria analyses for dose escalation, frequent laboratory and clinical observations, correlation of AEs with plasma concentrations of SNX-5422 and SNX-2112, monitoring of the QTc interval at appropriate time points, and a conservative dose-escalation scheme.