Aurora kinases are oncogenic
serine/threonine kinases that play key roles in regulating the mitotic phase of the eukaryotic cell cycle. Auroras are overexpressed in numerous
tumors including B-cell non-Hodgkin's
lymphomas and are validated oncology targets.
AT9283, a pan-aurora inhibitor inhibited growth and survival of multiple solid
tumors in vitro and in vivo. In this study, we demonstrated that
AT9283 had potent activity against Aurora B in a variety of aggressive B-(
non-Hodgkin lymphoma) B-NHL cell lines. Cells treated with
AT9283 exhibited endoreduplication confirming the mechanism of action of an Aurora B inhibitor. Also, treatment of B-NHL cell lines with
AT9283 induced apoptosis in a dose and time dependent manner and inhibited cell proliferation with an IC(50) < 1 μM. It is well known that inhibition of auroras (A or B) synergistically enhances the effects of microtubule targeting agents such as
taxanes and
vinca alkaloids to induce antiproliferation and apoptosis. We evaluated whether
AT9283 in combination with
docetaxel is more efficient in inducing apoptosis than
AT9283 or
docetaxel alone. At very low doses (5 nM) apoptosis was doubled in the combination (23%) compared to
AT9283 or
docetaxel alone (10%). A mouse xenograft model of
mantle cell lymphoma demonstrated that
AT9283 at 15 mg/kg and
docetaxel (10 mg/kg) alone had modest anti-
tumor activity. However,
AT9283 at 20 mg/kg and
AT9283 (15 or 20 mg/kg) plus
docetaxel (10 mg/kg) demonstrated a statistically significant
tumor growth inhibition and enhanced survival. Together, our results suggest that
AT9283 plus
docetaxel may represent a novel therapeutic strategy in B-cell NHL and warrant early phase clinical trial evaluation.