Douglas Bowman

MLN8054, a Small-Molecule Inhibitor of Aurora A, Causes Spindle Pole and Chromosome Congression Defects Leading to Aneuploidy

ABSTRACT Aurora A kinase plays an essential role in the proper assembly and function of the mitotic spindle, as its perturbation causes defects in centrosome separation, spindle pole organization, and chromosome congression. Moreover, Aurora A disruption leads to cell death via a mechanism that involves aneuploidy generation. However, the link between the immediate functional consequences of Aurora A inhibition and the development of aneuploidy is not clearly defined. In this study, we delineate the sequence of events that lead to aneuploidy following Aurora A inhibition using MLN8054, a selective Aurora A small-molecule inhibitor. Human tumor cells treated with MLN8054 show a high incidence of abnormal mitotic spindles, often with unseparated centrosomes. Although these spindle defects result in mitotic delays, cells ultimately divide at a frequency near that of untreated cells. We show that many of the spindles in the dividing cells are bipolar, although they lack centrosomes at one or more spindle poles. MLN8054-treated cells frequently show alignment defects during metaphase, lagging chromosomes in anaphase, and chromatin bridges during telophase. Consistent with the chromosome segregation defects, cells treated with MLN8054 develop aneuploidy over time. Taken together, these results suggest that Aurora A inhibition kills tumor cells through the development of deleterious aneuploidy.

Localization of human TACC3 to mitotic spindles is mediated by phosphorylation on Ser558 by Aurora A: a novel pharmacodynamic method for measuring Aurora A activity.

Aurora A is a serine/threonine protein kinase essential for normal mitotic progression. Aberrant increased expression of Aurora A, which occurs frequently in human cancers, results in abnormal mitoses leading to chromosome instability and possibly tumorigenesis. Consequently, Aurora A has received considerable attention as a potential target for anticancer therapeutic intervention. Aurora A coordinates several essential mitotic activities through phosphorylation of a variety of proteins, including TACC3, which modulates microtubule stabilization of the mitotic spindle. Recent studies identified a conserved serine in Xenopus (Ser(626)) and Drosophila (Ser(863)) TACC3 orthologues that is phosphorylated by Aurora A. We show that this conserved serine on human TACC3 (Ser(558)) is also phosphorylated by Aurora A. Moreover, phosphorylation of TACC3 by Aurora A in human cells is essential for its proper localization to centrosomes and proximal mitotic spindles. Inhibition of Aurora A with the selective small molecule inhibitor MLN8054 in cultured human tumor cells resulted in mislocalization of TACC3 away from mitotic spindles in a concentration-dependent manner. Furthermore, oral administration of MLN8054 to nude mice bearing HCT-116 human tumor xenografts caused a dose-dependent mislocalization of TACC3 away from spindle poles that correlated with tumor growth inhibition. As TACC3 localization to mitotic spindles depends on Aurora A-mediated phosphorylation, quantifying TACC3 mislocalization represents a novel pharmacodynamic approach for measuring Aurora A activity in cancer patients treated with inhibitors of Aurora A kinase.

Phase I study of the selective Aurora A kinase inhibitor MLN8054 in patients with advanced solid tumors: safety, pharmacokinetics, and pharmacodynamics

This phase I trial examined the safety, pharmacokinetics, and pharmacodynamics of MLN8054, an oral, selective, small-molecule inhibitor of Aurora A kinase. Patients with advanced solid tumors received increasing doses of MLN8054 in 28-day cycles until dose-limiting toxicity (DLT) was seen in ≥2 of 3-6 patients in a cohort. For the 10-mg and 20-mg cohorts, treatment was administered once daily on days 1 to 5 and 8 to 12. Patients in later cohorts (25, 35, 45, 55, 60, 70, and 80 mg/day) were treated four times daily on days 1 to 14, with the largest dose at bedtime (QID-14D) to mitigate benzodiazepine-like effects possibly associated with peak plasma concentrations. Patients (n = 43) received a median of 1 cycle (range, 1–10). DLT of somnolence was first noted in the 20-mg cohort. Two DLTs of somnolence (n = 1) and transaminitis (n = 1) were seen at QID-14D 80 mg. Grade 2 oral mucositis (n = 1), predicted to be a mechanistic effect, was observed only at QID-14D 80 mg. MLN8054 exposure levels were roughly linear with dose; terminal half-life was 30 to 40 hours. Pharmacodynamic analyses of skin and tumor mitotic indices, mitotic cell chromosome alignment, and spindle bipolarity provided evidence of Aurora A inhibition. MLN8054 dosing for 10 to 14 days in 28-day cycles was feasible. Somnolence and transaminitis were DLTs. Pharmacodynamic analyses in mitotic cells of both skin and tumor provided proof of mechanism for Aurora A kinase inhibition. A more potent, selective, second-generation Aurora A kinase inhibitor, MLN8237, is in clinical development. Mol Cancer Ther; 9(10); 2844–52. ©2010 AACR.

Phase I assessment of new mechanism-based pharmacodynamic biomarkers for MLN8054, a small-molecule inhibitor of Aurora A kinase

The mitotic kinase Aurora A is an important therapeutic target for cancer therapy. This study evaluated new mechanism-based pharmacodynamic biomarkers in cancer patients in two phase I studies of MLN8054, a small-molecule inhibitor of Aurora A kinase. Patients with advanced solid tumors received MLN8054 orally for 7 consecutive days in escalating dose cohorts, with skin and tumor biopsies obtained before and after dosing. Skin biopsies were evaluated for increased mitotic cells within the basal epithelium. Tumor biopsies were assessed for accumulation of mitotic cells within proliferative tumor regions. Several patients in the highest dose cohorts showed marked increases in the skin mitotic index after dosing. Although some tumors exhibited increases in mitotic cells after dosing, others displayed decreases, a variable outcome consistent with dual mechanisms of mitotic arrest and mitotic slippage induced by antimitotics in tumors. To provide a clearer picture, mitotic cell chromosome alignment and spindle bipolarity, new biomarkers of Aurora A inhibition that act independently of mitotic arrest or slippage, were assessed in the tumor biopsies. Several patients, primarily in the highest dose cohorts, had marked decreases in the percentage of mitotic cells with aligned chromosomes and bipolar spindles after dosing. Evidence existed for an exposure-effect relationship for mitotic cells with defects in chromosome alignment and spindle bipolarity that indicated a biologically active dose range. Outcomes of pharmacodynamic assays from skin and tumor biopsies were concordant in several patients. Together, these new pharmacodynamic assays provide evidence for Aurora A inhibition by MLN8054 in patient skin and tumor tissues.

Discovery of a Potent and Orally Bioavailable Benzolactam-Derived Inhibitor of Polo-Like Kinase 1 (MLN0905).

This article describes the discovery of a series of potent inhibitors of Polo-like kinase 1 (PLK1). Optimization of this benzolactam-derived chemical series produced an orally bioavailable inhibitor of PLK1 (12c, MLN0905). In vivo pharmacokinetic-pharmacodynamic experiments demonstrated prolonged mitotic arrest after oral administration of 12c to tumor bearing nude mice. A subsequent efficacy study in nude mice achieved tumor growth inhibition or regression in a human colon tumor (HT29) xenograft model.

Applications of Pathology-Assisted Image Analysis of Immunohistochemistry-Based Biomarkers in Oncology

Immunohistochemistry-based biomarkers are commonly used to understand target inhibition in key cancer pathways in preclinical models and clinical studies. Automated slide-scanning and advanced high-throughput image analysis software technologies have evolved into a routine methodology for quantitative analysis of immunohistochemistry-based biomarkers. Alongside the traditional pathology H-score based on physical slides, the pathology world is welcoming digital pathology and advanced quantitative image analysis, which have enabled tissue- and cellular-level analysis. An automated workflow was implemented that includes automated staining, slide-scanning, and image analysis methodologies to explore biomarkers involved in 2 cancer targets: Aurora A and NEDD8-activating enzyme (NAE). The 2 workflows highlight the evolution of our immunohistochemistry laboratory and the different needs and requirements of each biological assay. Skin biopsies obtained from MLN8237 (Aurora A inhibitor) phase 1 clinical trials were evaluated for mitotic and apoptotic index, while mitotic index and defects in chromosome alignment and spindles were assessed in tumor biopsies to demonstrate Aurora A inhibition. Additionally, in both preclinical xenograft models and an acute myeloid leukemia phase 1 trial of the NAE inhibitor MLN4924, development of a novel image algorithm enabled measurement of downstream pathway modulation upon NAE inhibition. In the highlighted studies, developing a biomarker strategy based on automated image analysis solutions enabled project teams to confirm target and pathway inhibition and understand downstream outcomes of target inhibition with increased throughput and quantitative accuracy. These case studies demonstrate a strategy that combines a pathologist’s expertise with automated image analysis to support oncology drug discovery and development programs.

An introduction to high content screening : imaging technology, assay development, and data analysis in biology and drug discovery

New updated! The latest book from a very famous author finally comes out. Book of an introduction to high content screening imaging technology assay development and data analysis in biology and drug discovery, as an amazing reference becomes what you need to get. Whats for is this book? Are you still thinking for what the book is? Well, this is what you probably will get. You should have made proper choices for your better life. Book, as a source that may involve the facts, opinion, literature, religion, and many others are the great friends to join with.

A Sensitive IHC Method for Monitoring Autophagy-Specific Markers in Human Tumor Xenografts

Objective. Use of tyramide signal amplification (TSA) to detect autophagy biomarkers in formalin fixed and paraffin embedded (FFPE) xenograft tissue. Materials and Methods. Autophagy marker regulation was studied in xenograft tissues using Amp HQ IHC and standard IHC methods. Results. The data demonstrate the feasibility of using high sensitivity TSA IHC assays to measure low abundant autophagy markers in FFPE xenograft tissue.

Colloquium: SBI2 HCS/HCA Informatics and Data Analysis - Best Practices and Unmet Needs September 15, 2015

S BI led an Informatics and Data Analysis Colloquium on the first day of the SBI Annual Conference: an exciting opportunity for attendees to join a guided roundtable discussion on the key informatics and data analysis challenges that HCS practitioners encounter. Each topic was led by a topic discussion leader who solicited feedback from the high content screening/high content analysis (HCS/HCA) community before the conference. Each topic discussion included an introduction by the topic leader, presentations from community participants, and an open discussion with all attendees. There were *80 people at the colloquium, including education session instructors, scientific program presenters, attendees, and vendors. The topic discussion leaders were as follows:

Abstract 5041: Translational pharmacokinetic-pharmacodynamic xenograft model for TAK-931, a small molecule cell division cycle 7 (CDC7) kinase inhibitor

TAK-931 is a small molecule inhibitor of the cell division cycle 7 (CDC7) kinase. As a serine/threonine kinase that contributes to DNA replication and the DNA damage response, CDC7 is hypothesized to be a promising cancer drug target. CDC7 inhibition with TAK-931 has demonstrated antiproliferative activity with cancer cell lines and tumor growth inhibition (TGI) in murine ectopic xenograft models. Herein, the analysis of multiple models to characterize pharmacokinetic (PK) and pharmacodynamic (PD) relationships with xenograft TGI is described. TAK-931 treatment-induced TGI was dose schedule-independent and could be described using plasma drug concentrations or tumor PD inhibition. However, the efficacious doses were at least 10-fold higher for the PK-TGI relationship than for the PD-TGI relationship. This discrepancy was used to select a dynamic PK-PD-TGI modeling approach to project the minimal efficacious dose (MED) and minimal biological active dose (MBAD) for TAK-931 due to the large differences in time-concentration profiles predicted for humans versus mice. The Phase I human trial is on-going and will be used to verify the dynamic PK-PD-driven modeling approach for the CDC7 inhibitor. Citation Format: Charles Locuson, Mayank Patel, Akihiro Ohashi, Kenichi Iwai, Tadahiro Nambu, Toshiyuki Takeuchi, Akifumi Kogame, Douglas Bowman, Stephen Tirrell, Huifeng Niu, Cindy Xia. Translational pharmacokinetic-pharmacodynamic xenograft model for TAK-931, a small molecule cell division cycle 7 (CDC7) kinase inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5041. doi:10.1158/1538-7445.AM2017-5041