The orally bioavailable mesylate salt of the 17-allylaminogeldanamycin (17-AAG) small-molecule inhibitor of several receptor protein tyrosine kinases with potential antiangiogenic and antineoplastic activities. Telatinib binds to and inhibits the vascular endothelial growth factor receptors (VEGFRs) type 2 and 3, platelet-derived growth factor receptor beta (PDGFRb) and c-Kit, which may result in the inhibition of angiogenesis and cellular proliferation in tumors in which these receptors are upregulated. These telatinib-inhibited receptor protein tyrosine kinases are overexpressed or mutated in many tumor cell types and may play key roles in tumor angiogenesis and tumor cell proliferation. 17-AAG is a synthetic analogue of the benzoquinone ansamycin antibiotic geldanamycin and has also been found to inhibit the molecular chaperone Hsp90.