HSP90 inhibitors as therapy for multiple myeloma.

The heat shock protein 90 (HSP90) family of proteins are ubiquitous molecular chaperones that are intricately involved in folding, activation, maturation, and assembly of many proteins that include essential mediators of signal transduction and cell cycle progression. They are abundant in eukaryotic cells and localized to the cytoplasm and mitochondria as well as the endoplasmic reticulum under normal conditions, making up 1% to 2% of all cellular proteins. HSP90 proteins have increased expression in a number of malignancies, including multiple myeloma. HSP90 inhibition can influence multiple oncogenic pathways and proteins involved in myeloma, therefore making it an attractive target for drug development in this disease. This article serves as an overview of the pre-clinical data and clinical trial data on HSP90 inhibitors in multiple myeloma.