AMG 900, a potent inhibitor of aurora kinases causes pharmacodynamic changes in p-Histone H3 immunoreactivity in human tumor xenografts and proliferating mouse tissues.

BACKGROUND: The Aurora family of serine-threonine kinases are essential regulators of cell division in mammalian cells. Aurora-A and -B expression and kinase activity is elevated in a variety of human cancers and is associated with high proliferation rates and poor prognosis. AMG 900 is a highly potent and selective pan-aurora kinase inhibitor that has entered clinical evaluation in adult patients with advanced cancers. In mice, oral administration of AMG 900 blocks the phosphorylation of histone H3 on serine-10 (p-Histone H3), a proximal substrate of aurora-B and inhibits the growth of multiple human tumor xenografts, including multidrug-resistant models. METHODS: In order to establish a preclinical pharmacokinetic-pharmacodynamic (PK-PD) relationship for AMG 900 that could be translated to the clinic, we used flow cytometry and laser scanning cytometry detection platforms to assess the effects on p-Histone H3 inhibition in terms of sensitivity, precision, and specificity, in human tumor xenografts in conjunction with mouse skin and bone marrow tissues. Mice with established COLO 205 tumors were administered AMG 900 at 3.75, 7.5, and 15 mg/kg and assessed after 3 hours. RESULTS: Significant suppression of p-Histone H3 in mouse skin was only observed at 15 mg/kg (p <0.0001), whereas in mouse bone marrow and in tumor a dose-dependent inhibition was achieved at all three doses (p ≤ 0.00015). These studies demonstrate that AMG 900 inhibits p-Histone H3 in tumors and surrogate tissues (although tissues such as skin may be less sensitive for assessing PD effects). To further extend our work, we evaluated the feasibility of measuring p-Histone H3 using fine-needle aspirate (FNA) tumor xenograft biopsies. Treatment with AMG 900 significantly inhibited p-Histone H3 (>99% inhibition, p <0.0001) in COLO 205 tumors. Lastly, we illustrate this LSC-based approach can detect p-Histone H3 positive cells using mock FNAs from primary human breast tumor tissues. CONCLUSION: Phosphorylation of histone H3 is a useful biomarker to determine the pharmacodynamics (PD) activity of AMG 900. FNA biopsies may be a viable approach for assessing AMG 900 PD effects in the clinic.

Measurement of conatumumab-induced apoptotic activity in tumors by fine needle aspirate sampling.

Conatumumab is a monoclonal antibody specific for death receptor 5 (DR5) that activates caspases leading to DNA fragmentation and tumor-cell death. Like other Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL) receptor therapies, conatumumab is currently being evaluated in clinical trials across a variety of tumor types. However, molecular evidence of on-target drug activity in tumors is often an elusive goal for clinical investigation. Here we evaluated a translational approach using a relevant biopsy method, fine needle aspirates (FNAs), to study the on-target pharmacodynamics of conatumumab pre-clinically. As detected by laser scanning cytometry, drug-induced caspase-3 activation in FNA biopsies of Colo205 xenografts correlated well with activated caspase-3 in conventional section-based samples. Furthermore, in tumor-bearing mice, surrogate assays of serum caspase-3/7 activity and serum drug exposure correlated with in situ caspase-3 activation. We found that one advantage of FNA sampling over other sampling techniques was the ability to measure caspase activity on a per cell basis using DNA content information. To adapt the utility of FNAs for measuring pharmacodynamic markers in humans, detection of activated caspase-3 was multiplexed with EpCAM to characterize mock and clinical FNAs from colorectal and nonsmall cell lung cancer patients. These data suggest that FNA sampling is a practical method to cytometrically evaluate tumors for pharmacological impact in a clinical setting.

Antibiotic utilization improvement with the Nanosphere Verigene Gram-Positive Blood Culture assay.

New technologies offer rapid identification of organisms and antimicrobial resistance markers in blood cultures several hours faster than conventional methods. We sought to determine whether implementation of the Verigene® Gram-Positive Blood Culture (BC-GP) assay paired with a well-defined results reporting algorithm would lead to earlier deescalation of empiric therapy for inpatients with methicillin-sensitive Staphylococcus aureus (MSSA) and vancomycin-resistant Enterococcus (VRE) bacteremia. The algorithm design focused on lessening the demand for pharmacist time by using electronic communications where possible. Our study compared inpatients with MSSA and VRE bacteremia from the time period before (pre-BC-GP) and after (post-BC-GP) implementation of the assay on June 25, 2013. The time from blood draw to identification and susceptibility results was decreased by 36.4 hours (P < 0.001) in the post-BC-GP group. The mean time from collection to the first dose of optimal antibiotics was reduced in the post-BC-GP group by 18.9 hours (P = 0.004) overall, with a 20.6-hour reduction (P = 0.009) for patients with MSSA and a 20.7-hour reduction (P = 0.077) for patients with VRE. Additionally, the percent of patients on empiric therapy who were placed on optimal antibiotics at any time after the Gram stain result was available increased from 64% (45/70) pre-BC-GP to 80% (43/54) post-BC-GP. The BC-GP led to an increased rate of deescalation of empiric antibiotics and a reduction in the time to optimal antibiotics for patients with MSSA and VRE bacteremia.