Abstract 3008: Preclinical characterization of AMG 900, a pan-aurora kinase inhibitor, alone and in combination with taxanes in ovarian cancer
Authors: Kalous Ondrej , Conklin Dylan , Manivong Kanthinh , Wayne William , Hanestad Kelly , Canon Jude , Loberg Robert , Friberg Gregory , Gamelin Erick , Vogl Florian D. , Juan Gloria , Coxon Angela , Slamon Dennis , Finn Richard , Payton Marc 
Published: July 2016

BACKGROUND: Aurora kinases (AK) A and B play essential roles in multiple stages of mitosis and are frequently overexpressed in a subset of human cancers, including ovarian cancer (OC). AMG 900, a potent and highly selective small molecule inhibitor of AKs, showed promising single-agent activity in heavily pretreated patients with advanced OC in a Phase 1b clinical trial. In this study, we report the preclinical effects of AMG 900 in a panel of well-characterized human cancer cell lines representing clinically-relevant OC subtypes. METHODS: The anti-proliferative effects of AMG 900 were evaluated using a 5-day cell count assay. Cell lines were classified as sensitive to AMG 900 when lethality was &gt; 15% at 10 nM. Molecular markers were profiled including TP53 mutation status, AURKA, CCNE1, MYC copy number, and p53, p21 and cyclin E1 protein by reverse phase protein array. Flow cytometry and imaging methods were used to evaluate the mechanism of action of AMG 900 alone and in combination with chemotherapy. The combination of AMG 900 plus docetaxel was evaluated in an IGROV-1 ovarian endometrioid carcinoma xenograft model. RESULTS: One third of the cell lines (11 of 35) were classified as sensitive to AMG 900 and showed enrichment for TP53 mutations and serous OC subtype. However, 10 of 24 resistant cell lines harbored TP53 mutations, indicating that TP53 mutational status alone was not sufficient for predicting AMG 900 sensitivity. Inhibition of AK activity by AMG 900 in OC cells resulted in aborted cell division leading to polyploidy and cell death (suggestive of aurora-B dominant phenotype). Re-plating of remnant cells after AMG 900 treatment showed an attenuation of cell regrowth, where TP53mut IGROV-1 cells showed minimal regrowth compared to TP53wt OVCAR-5 cells. AMG 900 inhibited proliferation at low nanomolar concentrations in the majority of OC cell lines and enhanced the effects of paclitaxel, carboplatin, and doxorubicin in IGROV-1 cells. In tumor-bearing mice, administration of AMG 900 at 7.5 mg/kg (PO) for two days per week or docetaxel at 10 mg/kg (IP) weekly for four cycles significantly inhibited the growth of IGROV-1 tumor xenografts (P &lt; .0001 vs. vehicle alone). Notably, co-administration of AMG 900 with docetaxel enhanced efficacy and induced a delay in tumor regrowth compared to docetaxel alone. Single-agent-treated mice showed minimal body weight loss (BWL), whereas combination-treated mice showed moderate BWL (average &lt; 10%) that was largely reversible (2 of 12 animals removed due to toxicity). CONCLUSIONS: AMG 900 alone or in combination with chemotherapy such as paclitaxel may be a promising clinical strategy to treat patients with ovarian cancer.

Citation Format: Ondrej Kalous, Dylan Conklin, Kanthinh Manivong, William Wayne, Kelly Hanestad, Jude Canon, Robert Loberg, Gregory Friberg, Erick Gamelin, Florian D. Vogl, Gloria Juan, Angela Coxon, Dennis Slamon, Richard Finn, Marc Payton. Preclinical characterization of AMG 900, a pan-aurora kinase inhibitor, alone and in combination with taxanes in ovarian cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3008.