LY2801653 is an orally bioavailable multi-kinase inhibitor with potent activity against MET, MST1R, and other oncoproteins, and displays anti-tumor activities in mouse xenograft models.

The HGF/MET signaling pathway regulates a wide variety of normal cellular functions that can be subverted to support neoplasia, including cell proliferation, survival, apoptosis, scattering and motility, invasion, and angiogenesis. MET over-expression (with or without gene amplification), aberrant autocrine or paracrine ligand production, and missense MET mutations are mechanisms that lead to activation of the MET pathway in tumors and are associated with poor prognostic outcome. We report here preclinical development of a potent, orally bioavailable, small-molecule inhibitor LY2801653 targeting MET kinase. LY2801653 is a type-II ATP competitive, slow-off inhibitor of MET tyrosine kinase with a dissociation constant (Ki) of 2 nM, a pharmacodynamic residence time (Koff) of 0.00132 min(-1) and t1/2 of 525 min. LY2801653 demonstrated in vitro effects on MET pathway-dependent cell scattering and cell proliferation; in vivo anti-tumor effects in MET amplified (MKN45), MET autocrine (U-87MG, and KP4) and MET over-expressed (H441) xenograft models; and in vivo vessel normalization effects. LY2801653 also maintained potency against 13 MET variants, each bearing a single-point mutation. In subsequent nonclinical characterization, LY2801653 was found to have potent activity against several other receptor tyrosine oncokinases including MST1R, FLT3, AXL, MERTK, TEK, ROS1, DDR1/2 and against the serine/threonine kinases MKNK1/2. The potential value of MET and other inhibited targets within a number of malignancies (such as colon, bile ducts, and lung) is discussed. LY2801653 is currently in phase 1 clinical testing in patients with advanced cancer (trial I3O-MC-JSBA, NCT01285037).

Optimization of a dihydropyrrolopyrazole series of transforming growth factor-beta type I receptor kinase domain inhibitors: discovery of an orally bioavailable transforming growth factor-beta receptor type I inhibitor as antitumor agent.

In our continuing effort to expand the SAR of the quinoline domain of dihydropyrrolopyrazole series, we have discovered compound 15d, which demonstrated the antitumor efficacy with oral bioavailability. This effort also demonstrated that the PK/PD in vivo target inhibition paradigm is an effective approach to assess potential for antitumor efficacy. The dihydropyrrolopyrazole inhibitor 15d (LY2109761) is representative of a novel series of antitumor agents.

Development of a Transcreener kinase assay for protein kinase A and demonstration of concordance of data with a filter-binding assay format.

A Transcreener kinase fluorescence polarization (FP) assay has been developed for the serine/threonine kinase protein kinase A (PKA). The PKA Transcreener kinase assay is an homogenous, competitive antibody-based FP assay that uses Far Red Alexa Fluor 633-labeled adenosine 5' disphosphate (ADP) tracer and mouse monoclonal anti-ADP antibody. The Transcreener PKA assay was validated with both known PKA inhibitors and library compounds. The Transcreener PKA assay is resistant to low-wavelength (or common) fluorescent interference from small-molecule library compounds and generates IC50 results comparable with current radioactive filter-binding assay.

The protein kinase Cbeta-selective inhibitor, Enzastaurin (LY317615.HCl), suppresses signaling through the AKT pathway, induces apoptosis, and suppresses growth of human colon cancer and glioblastoma xenografts.

Activation of protein kinase Cbeta (PKCbeta) has been repeatedly implicated in tumor-induced angiogenesis. The PKCbeta-selective inhibitor, Enzastaurin (LY317615.HCl), suppresses angiogenesis and was advanced for clinical development based upon this antiangiogenic activity. Activation of PKCbeta has now also been implicated in tumor cell proliferation, apoptosis, and tumor invasiveness. Herein, we show that Enzastaurin has a direct effect on human tumor cells, inducing apoptosis and suppressing the proliferation of cultured tumor cells. Enzastaurin treatment also suppresses the phosphorylation of GSK3betaser9, ribosomal protein S6(S240/244), and AKT(Thr308). Oral dosing with Enzastaurin to yield plasma concentrations similar to those achieved in clinical trials significantly suppresses the growth of human glioblastoma and colon carcinoma xenografts. As in cultured tumor cells, Enzastaurin treatment suppresses the phosphorylation of GSK3beta in these xenograft tumor tissues. Enzastaurin treatment also suppresses GSK3beta phosphorylation to a similar extent in peripheral blood mononuclear cells (PBMCs) from these treated mice. These data show that Enzastaurin has a direct antitumor effect and that Enzastaurin treatment suppresses GSK3beta phosphorylation in both tumor tissue and in PBMCs, suggesting that GSK3beta phosphorylation may serve as a reliable pharmacodynamic marker for Enzastaurin activity. With previously published reports, these data support the notion that Enzastaurin suppresses tumor growth through multiple mechanisms: direct suppression of tumor cell proliferation and the induction of tumor cell death coupled to the indirect effect of suppressing tumor-induced angiogenesis.

Development of a microplate-based, electrophoretic fluorescent protein kinase a assay: comparison with filter-binding and fluorescence polarization assay formats.

A microplate-based electrophoretic assay has been developed for the serine/threonine kinase protein kinase A (PKA). The ElectroCapture PKA assay developed uses a positively charged, lissamine-rhodamine-labeled kemptide peptide substrate for the kinase reaction and Nanogen's ElectroCapture HTS Workstation and 384-well laminated membrane plates to electrophoretically separate the negatively charged phosphorylated peptide product from the kinase reaction mix. After the electrophoretic separation, the amount of rhodamine-labeled phosphopeptide product was quantified using a Tecan Ultra384 fluorescence reader. The ElectroCapture PKA assay was validated with both known PKA inhibitors and library compounds. The pK(iapp) results obtained in the ElectroCapture PKA assay were comparable to those generated with current radioactive filter-binding assay and antibody-based competitive fluorescence polarization PKA assay formats.

Capture of drug targets from live cells using a multipurpose immuno-chemo-proteomics tool.

Recently we have described the development of an Immuno-chemo-proteomics method for drug target deconvolution and profiling the toxicity of known drugs ( Saxena , C. ; Zhen , E. ; Higgs , R. E. ; Hale , J. E. J. Proteome Res. 2008, 8 , 3490 - 3497 ). The orthogonal nature and advantage of the newly developed method over existing ones were presented. Most commonly, a small molecule was coupled to an epitope and used as an affinity probe to bind targets and later antibody against the epitope was used to isolate the probe-protein complex. However, such studies performed using cell lysates are prone to false positive identification because the protein source is not in its native physiological condition. Here we describe the development and application of a multipurpose soluble probe where a small molecule was coupled to a fluorophore-tagged cell-permeable peptide epitope, which was used to affinity isolate binding proteins from live cells. Fluorophore coupling allowed direct visualization of the compound in the cells, and cell permeability of the probe provided opportunity to capture the targets from the live cell. The GSK3-beta inhibitor Bisindolylmaleimide-III was coupled to a peptide containing the fluorescein-tagged TAT epitope. Following incubation with the live cells, the compound and associated proteins were affinity isolated using antifluorescein antibody beads. Using this approach, we captured the known Bisindolylmaleimide-III target GSK3-beta and previously unidentified targets from live cells. Dose-dependent inhibition of target binding to probe in the presence of uncoupled compound validated the approach. This method was directly compared with the one where cell lysate was used as the protein source providing an advanced strategy to aid in target deconvolution and help to eliminate false positives originating from non-native protein source.