New Anticancer 4-Aryldihydropyrimidinone-5-Carboxylates Targeting Hsp90

Amplified expression of the heat shock protein 90 (Hsp90) chaperone within cancer cells is associated with poor patient prognosis, and is known to drive tumour invasion, treatment resistance and metastasis within a range of tumour types. Several Hsp90 small molecule inhibitors have progressed into clinical development; however, progress in the clinic to date has been sub-optimal, and new Hsp90 inhibitor chemical scaffolds are needed to realise the full potential of this target. Following identification of a virtual hit compound able to mimic interactions of the Hsp90 inhibitor geldanamycin within the Hsp90 ATP binding site, we have designed and synthesised a range of substituted 4-aryldihydropyrimidinone-5-carboxylate derivatives (5a-n) for structure-activity relationship (SAR) study as Hsp90 inhibitors within human breast cancer cell models. Compound 5d emerged as the most promising analogue, combining low levels of growth inhibition with potent inhibition of colony formation in breast cancer cell lines, and effective Hsp90 inhibition. Early ADME profiling confirmed 5d to have moderate metabolic stability and solubility, and to lack hERG channel inhibition, confirming 5d as a useful hit compound for further development.