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The expression of RHAMM and other centrosome-associated genes are known to correlate with the extent of centrosome amplification in multiple myeloma, and with poor prognosis. RHAMM has a significant interaction with TPX2, a protein which regulates the localization and action of Aurora A kinase (AURKA) at the spindle poles. AURKA is known to be a central determinant of centrosome and spindle function and is a target for cancer therapy. Given these observations, we investigated the role of Aurora kinases as therapeutic targets in myeloma. Here we report that AURKA is expressed ubiquitously in myeloma, to varying degrees, in both cell lines and patients' bone marrow plasma cells. siRNA targeting AURKA induces apoptotic cell death in myeloma cell lines. The Aurora kinase inhibitor VE-465 also induces apoptosis and death in myeloma cell lines and primary myeloma plasma cells. The combination of VE-465 and dexamethasone improves cell killing compared with the use of either agent alone, even in cells resistant to the single agents. The phenotype of myeloma cells treated with VE-465 is consistent with published reports on the effects of Aurora kinase inhibition. Aurora kinase inhibitors should be pursued as potential treatments for myeloma.

SummaryAurora kinases are potential targets for cancer therapy. Previous studies have validated Aurora kinase A as a therapeutic target in multiple myeloma (MM), and have demonstrated in vitro anti‐myeloma effects of small molecule Aurora kinase inhibitors that inhibit both Aurora A and B. This study demonstrated that Aurora B kinase was strongly expressed in myeloma cell lines and primary plasma cells. The selective Aurora B inhibitor AZD1152‐induced apoptotic death in myeloma cell lines at nanomolar concentrations, with a cell cycle phenotype consistent with that reported previously for Aurora B inhibition. In some cases, AZD1152 in combination with dexamethasone showed increased anti‐myeloma activity compared with the use of either agent alone. AZD1152 was active against sorted CD138+ BM plasma cells from myeloma patients but also, as expected, was toxic to CD138− marrow cells from the same patients. In a murine myeloma xenograft model, AZD1152‐inhibited tumour growth at well‐tolerated doses and induced cell death in established tumours, with associated mild, transient leucopenia. AZD1152 shows promise in these preclinical studies as a novel treatment for MM.

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