Spotlight on 17-AAG as an Hsp90 inhibitor for molecular targeted cancer treatment.

Hsp90 is a ubiquitous chaperone with important roles in the organization and maturation of client proteins that are involved in the progression and survival of cancer cells. Multiple oncogenic pathways can be affected by inhibition of Hsp90 function through degradation of its client proteins. That makes Hsp90 a therapeutic target for cancer treatment. 17-allylamino-17-demethoxy-geldanamycin (17-AAG) is a potent Hsp90 inhibitor that binds to Hsp90 and inhibits its chaperoning function, which results in the degradation of Hsp90's client proteins. There have been several preclinical studies of 17-AAG as a single agent or in combination with other anticancer agents for a wide range of human cancers. Data from various phases of clinical trials show that 17-AAG can be given safely at biologically active dosages with mild toxicity. Even though 17-AAG has suitable pharmacological potency, its low water solubility and high hepatotoxicity could significantly restrict its clinical use. Nanomaterials-based drug delivery carriers may overcome these drawbacks. In this paper, we review preclinical and clinical research on 17-AAG as a single agent and in combination with other anticancer agents. In addition, we highlight the potential of using nanocarriers and nanocombination therapy to improve therapeutic effects of 17-AAG.