Anti-myeloma activity of the novel 2-aminothienopyrimidine Hsp90 inhibitor NVP-BEP800.

The 90 kD heat shock protein (Hsp90) molecular chaperone sustains multiple components of oncogenic pathways and has recently emerged as a therapeutic target that is now being clinically tested in a number of malignancies. In order to address formulation issues and to deal with possible resistance mechanisms against small molecule Hsp90 inhibitors, a range of compounds based on different molecular scaffolds are now being developed. The present study preclinically tested the effects of the novel 2-aminothienopyrimidine class Hsp90 inhibitor NVP-BEP800, which is suitable for oral formulations, on multiple myeloma cells from established cell lines and on a larger cohort (n = 40) of primary myeloma samples. The drug effectively and specifically killed the majority of primary myeloma cells in coculture with bone marrow stromal cells and reliably entailed molecular consequences of Hsp90 blockade - such as survival pathway breakdown and client protein depletion - in multiple myeloma cells from cell lines as well as from patients. Collectively, the properties of this novel drug support clinical testing in multiple myeloma.