Victoria L. Peek

LY2875358, a Neutralizing and Internalizing Anti-MET Bivalent Antibody, Inhibits HGF-Dependent and HGF-Independent MET Activation and Tumor Growth

Purpose: MET, the receptor for hepatocyte growth factor (HGF), has been implicated in driving tumor proliferation and metastasis. High MET expression is correlated with poor prognosis in multiple cancers. Activation of MET can be induced either by HGF-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional upregulation or by HGF-dependent autocrine or paracrine mechanisms. Experimental Design/Results: Here, we report on LY2875358, a novel humanized bivalent anti-MET antibody that has high neutralization and internalization activities, resulting in inhibition of both HGF-dependent and HGF-independent MET pathway activation and tumor growth. In contrast to other bivalent MET antibodies, LY2875358 exhibits no functional agonist activity and does not stimulate biologic activities such as cell proliferation, scattering, invasion, tubulogenesis, or apoptosis protection in various HGF-responsive cells and no evidence of inducing proliferation in vivo in a monkey toxicity study. LY2875358 blocks HGF binding to MET and HGF-induced MET phosphorylation and cell proliferation. In contrast to the humanized one-armed 5D5 anti-MET antibody, LY2875358 induces internalization and degradation of MET that inhibits cell proliferation and tumor growth in models where MET is constitutively activated. Moreover, LY2875358 has potent antitumor activity in both HGF-dependent and HGF-independent (MET-amplified) xenograft tumor models. Together, these findings indicate that the mechanism of action of LY2875358 is different from that of the one-armed MET antibody. Conclusions: LY2875358 may provide a promising therapeutic strategy for patients whose tumors are driven by both HGF-dependent and HGF-independent MET activation. LY2875358 is currently being investigated in multiple clinical studies. Clin Cancer Res; 20(23); 6059–70. ©2014 AACR.

Human Splicing Factor SPF45 (RBM17) Confers Broad Multidrug Resistance to Anticancer Drugs When Overexpressed— a Phenotype Partially Reversed By Selective Estrogen Receptor Modulators

The splicing factor SPF45 (RBM17) is frequently overexpressed in many solid tumors, and stable expression in HeLa cells confers resistance to doxorubicin and vincristine. In this study, we characterized stable transfectants of A2780 ovarian carcinoma cells. In a 3-day cytotoxicity assay, human SPF45 overexpression conferred 3- to 21-fold resistance to carboplatin, vinorelbine, doxorubicin, etoposide, mitoxantrone, and vincristine. In addition, resistance to gemcitabine and pemetrexed was observed at the highest drug concentrations tested. Knockdown of SPF45 in parental A2780 cells using a hammerhead ribozyme sensitized A2780 cells to etoposide by approximately 5-fold relative to a catalytically inactive ribozyme control and untransfected cells, suggesting a role for SPF45 in intrinsic resistance to some drugs. A2780-SPF45 cells accumulated similar levels of doxorubicin as vector-transfected and parental A2780 cells, indicating that drug resistance is not due to differences in drug accumulation. Efforts to identify small molecules that could block SPF45-mediated drug resistance revealed that the selective estrogen receptor (ER) modulators tamoxifen and LY117018 (a raloxifene analogue) partially reversed SPF45-mediated drug resistance to mitoxantrone in A2780-SPF45 cells from 21-fold to 8- and 5-fold, respectively, but did not significantly affect the mitoxantrone sensitivity of vector control cells. Quantitative PCR showed that ERbeta but not ERalpha was expressed in A2780 transfectants. Coimmunoprecipitation experiments suggest that SPF45 and ERbeta physically interact in vivo. Thus, SPF45-mediated drug resistance in A2780 cells may result in part from effects of SPF45 on the transcription or alternate splicing of ERbeta-regulated genes.

Inhibition of Tumor Growth and Metastasis in Non–Small Cell Lung Cancer by LY2801653, an Inhibitor of Several Oncokinases, Including MET

Purpose: Lung cancer is the leading cause of cancer-related death worldwide. Sustained activation, overexpression, or mutation of the MET pathway is associated with a poor prognosis in a variety of tumors, including non–small cell lung cancer (NSCLC), implicating the MET pathway as a potential therapeutic target for lung cancer. Previously, we reported on the development of LY2801653: a novel, orally bioavailable oncokinase inhibitor with MET as one of its targets. Here, we discuss the evaluation of LY2801653 in both preclinical in vitro and in vivo NSCLC models. Experimental Design/Results: Treatment with LY2801653 showed tumor growth inhibition in tumor cell lines and patient-derived tumor xenograft models as a single agent (37.4%–90.0% inhibition) or when used in combination with cisplatin, gemcitabine, or erlotinib (66.5%–86.3% inhibition). Mechanistic studies showed that treatment with LY2801653 inhibited the constitutive activation of MET pathway signaling and resulted in inhibition of NCI-H441 cell proliferation, anchorage-independent growth, migration, and invasion. These in vitro findings were confirmed in the H441 orthotopic model where LY2801653 treatment significantly inhibited both primary tumor growth (87.9% inhibition) and metastasis (64.5% inhibition of lymph node and 67.7% inhibition of chest wall). Tumor-bearing animals treated with LY2801653 had a significantly greater survival time (87% increase compared with the vehicle-treated mice). In the MET-independent NCI-H1299 orthotopic model, treatment with LY2801653 showed a significant inhibition of primary tumor growth but not metastasis. Conclusions: Collectively, these results support clinical evaluation of LY2801653 in NSCLCs and suggest that differences in the MET activation of tumors may be predictive of response. Clin Cancer Res; 19(20); 5699–710. ©2013 AACR.

Abstract 2738: c-Met antibody LY2875358 (LA480) has pre-clinical enhanced efficacy with gastric cancer standard-of-care in vitro and in vivo

cMet is a member of the receptor tyrosine kinase family and is the receptor for hepatocyte growth factor (HGF). cMet has been implicated in the initiation and progression of cancer due to the range of activities that cMet stimulates including proliferation, migration, morphogenesis, and survival. Inappropriate activation of c-Met can be induced by ligand-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional upregulation, or by ligand-dependent autocrine or paracrine mechanisms. Indeed, amplification of the c-Met gene, with consequent protein overexpression and constitutive kinase activation, has been reported in a number of human cancers, including gastric, esophageal and non-small-cell lung carcinomas. It has been reported that ∼10-20% of gastric tumors have increased copy numbers of the MET gene and overexpression of c-Met significantly correlates with poor prognosis in gastric cancer. c-Met antibody LY2875358 treatment reduces proliferation of gastric cancer cell lines with ligand-independent activation of c-Met resulting from gene amplification. The ability of LY2875358 to internalize and deplete cell surface c-Met is implicated in its activity against ligand-independent driven gastric cell lines. Here, we demonstrate that the pre-clinical combination of c-Met antibody LY2875358 with gastric cancer standard-of-care treatment has better efficacy than either treatment alone, both in vitro and in vivo. These data suggest that LY2875358 in combination with standard-of-care may be a promising treatment for gastric cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2738. doi:1538-7445.AM2012-2738

Abstract 2734: c-Met antibody LY2875358 (LA480) shows differential antitumor effects in non-small cell lung cancer

c-Met is a member of the receptor tyrosine kinase family and is the receptor for hepatocyte growth factor (HGF). c-Met is involved in many mechanisms of cancer proliferation and metastasis. Inappropriate activation of c-Met can be induced by ligand-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional up-regulation, or by ligand-dependent autocrine or paracrine mechanisms. Lung cancer is the leading cause of cancer death worldwide. Despite the successful development of EGFR- or EML4-ALK-targetd therapies, treatment options remain limited for patients with advanced lung cancer, making the identification of new therapeutic targets essential. c-Met expression was reported in 41-72% non-small cell lung cancer (NSCLC), amplification of c-Met occurs in 5-10 % of patients, and c-Met mutations have been detected in 8-13% of patients. We have developed a bi-valent c-Met antibody LY2875358 (LA480), which blocks ligand-dependent and ligand-independent c-Met activations. It is currently in clinical development. Here, we have demonstrated that LY2875358 alone or in combination with standard-of-care (SOC) affected cell proliferation, migration and signal transduction in NSCLC cells with c-Met gene amplification, mutations and overexpression. In vitro, LY2875358 induces wild type and mutant c-Met internalization and degradation. In vivo, LY2875358 alone shows a marked antitumor activity in Met amplification NSCLC xenograft models. The combination of LY2875358 with SOC chemotherapeutics treatments has better efficacy than either treatment alone, both in vitro and in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2734. doi:1538-7445.AM2012-2734

Abstract 5465: LY2875358, a bivalent MET antibody with anti-tumor activity through blocking HGF as well as inducing degradation of MET, differentiates from a one-armed 5D5 MET antibody.

MET is involved in many mechanisms of cancer proliferation and metastasis. Inappropriate activation of MET can be induced by HGF-independent mechanisms such as gene amplification, specific genetic mutations, and transcriptional up-regulation, or by HGF-dependent autocrine or paracrine mechanisms. LY2875358 is a novel humanized bivalent MET antibody currently in phase I clinical testing (trial NCT01287546). LY2875358 has high neutralization and internalization activities against MET for inhibiting HGF-dependent and HGF-independent MET pathway activation and tumor growth. In HGF-dependent MET activation, LY2875358 blocks HGF binding to MET, HGF-induced MET phosphorylation and tumor growth both in cell culture and in mouse xenograft models, resembling activities of a humanized one-armed 5D5 MET antibody (monovalent antibody similar to Onartuzumab). In tumors with HGF-independent MET activation through MET gene amplification, LY2875358 induces internalization and degradation of MET, which results in decreased pMET and total MET, inhibition of cell proliferation and tumor growth in MKN45 and SNU5 gastric tumor lines and EBC-1 and H1993 NSCLC tumor lines. Moreover, LY2875358 enhances antitumor activity in combination with cisplatin or 5-FU in vitro and in vivo in MET amplified tumor cells. However, under the same ligand-independent conditions, the one-armed 5D5 antibody did not have anti-tumor activities. When HGF is added to tumor cells with high MET gene amplification, LY2875358 decreases cell proliferation, while the one-armed 5D5 antibody does not. In contrast to other bivalent MET antibodies, LY2875358 has no or otherwise negligible agonist activity and does not stimulate biological activities such as cell proliferation, scattering, invasion, tubulogenesis, apoptosis protection or angiogenesis in various HGF responsive cells. These findings indicate that LY2875358 has a different mechanism of action from the humanized one-armed 5D5 MET antibody. LY2875358 may be a promising therapy for treatment of patients whose tumors are driven by HGF-dependent and HGF-independent MET activation. Citation Format: Wei Zeng, Victoria Peek, Mark Wortinger, Jonathan Tetreault, Jinqi Xia, Jennifer Stephens, Kelly Credille, Darryl Ballard, Trish Brown-Augsburger, Jirong Lu, Chi-Kin Chow, Peter Vaillancourt, Ying Tang, Sau-Chi B. Yan, Ling Liu. LY2875358, a bivalent MET antibody with anti-tumor activity through blocking HGF as well as inducing degradation of MET, differentiates from a one-armed 5D5 MET antibody. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5465. doi:10.1158/1538-7445.AM2013-5465

Merestinib (LY2801653) inhibits neurotrophic receptor kinase (NTRK) and suppresses growth of NTRK fusion bearing tumors

Merestinib is an oral multi-kinase inhibitor targeting a limited number of oncokinases including MET, AXL, RON and MKNK1/2. Here, we report that merestinib inhibits neurotrophic receptor tyrosine kinases NTRK1/2/3 which are oncogenic drivers in tumors bearing NTRK fusion resulting from chromosomal rearrangements. Merestinib is shown to be a type II NTRK1 kinase inhibitor as determined by x-ray crystallography. In KM-12 cells harboring TPM3-NTRK1 fusion, merestinib exhibits potent p-NTRK1 inhibition in vitro by western blot and elicits an anti-proliferative response in two- and three-dimensional growth. Merestinib treatment demonstrated profound tumor growth inhibition in in vivo cancer models harboring either a TPM3-NTRK1 or an ETV6-NTRK3 gene fusion. To recapitulate resistance observed from type I NTRK kinase inhibitors entrectinib and larotrectinib, we generated NIH-3T3 cells exogenously expressing TPM3-NTRK1 wild-type, or acquired mutations G595R and G667C in vitro and in vivo. Merestinib blocks tumor growth of both wild-type and mutant G667C TPM3-NTRK1 expressing NIH-3T3 cell-derived tumors. These preclinical data support the clinical evaluation of merestinib, a type II NTRK kinase inhibitor (NCT02920996), both in treatment naïve patients and in patients progressed on type I NTRK kinase inhibitors with acquired secondary G667C mutation in NTRK fusion bearing tumors.

MET-targeting antibody (emibetuzumab) and kinase inhibitor (merestinib) as single agent or in combination in a cancer model bearing MET exon 14 skipping

SummaryPurpose Approximately 3% of lung cancer bears mutations leading to MET exon 14 skipping, an oncogenic driver which is further evidenced by case reports of patient response to MET kinase inhibitor treatment. Approximately 15% of tumors harboring MET exon14 skipping have concurrent MET amplification. Experimental Design Merestinib is a type II MET kinase inhibitor. Emibetuzumab, a bivalent anti-MET antibody, internalizes MET receptor. Each single agent and the combination were evaluated in the Hs746t gastric cancer line bearing MET exon14 skipping and MET amplification. Results Merestinib inhibited Hs746t cell proliferation (IC50=34 nM) and totally eliminated pMET at 100nM. Emibetuzumab showed little anti-proliferative activity against Hs746t cells (IC50>100nM), did not reduce pMET, and slightly reduced cell surface MET. In the Hs746t xenograft model, dose dependent differences in durability of response were seen with merestinib including durable tumor regression (91.8%) at 12 mg/kg qd. Emibetuzumab treatment (10mg/kg qw) provided transient tumor regression (37.7%), but tumors re-grew while on treatment. Concurrent combination of merestinib (6 mg/kg qd) and emibetuzumab resulted in 85% tumor regression, while a sequential combination (initiating merestinib first) resulted in longer duration of treatment response. Conclusions Data in this study support a clinical evaluation of merestinib in patients with MET exon 14 skipping (NCT02920996). As a type II MET kinase inhibitor, merestinib may provide a therapeutic option to treatment naïve patients or to patients who progress on type I MET inhibitor treatment. Data also support clinical evaluation of the sequential combination of merestinib with emibetuzumab when patients progress on single agent merestinib.

Abstract 1738: Assay development for detecting cMET expression in circulating tumor cells (CTC), a potential patient tailoring marker for evaluation of cMET inhibitors

Hepatocyte growth factor and its receptor c-MET have been implicated in tumor formation and progression as well as drug treatment resistance to targeted agents such as EGFR inhibitors. cMET over-expression or gene amplification has been reported in a wide variety of human malignancies correlating with poor patient prognosis. A reasonable hypothesis for experimental agents targeting the cMET receptor is that patients with tumors expressing high levels of cMET may respond better. CTC counts are prognostic of survival in metastatic breast, colorectal, and prostate cancers (NEJM 2004;351:781-91; J Clin Oncol 2008;26:3213-21; Clin Can Res 2008;14:6302-9). CTCs are shed from tumors and are believed to be representative of cells migrating to form distal metastasis. The presence of these cells in blood provides an attractive and easy source for serial monitoring of tumors without the limitations of traditional solid tumor biopsy. We describe here the development of an assay that measures cMET expression in CTCs. The CTC assay was developed using the Veridex CellSearch® System, and RUO reagents for enumeration of CTCs and a Lilly proprietary cMET antibody (Ab) optD11. For assay development, cultured tumor cell lines with differing cMET expression levels representing solid epithelial tumor types were spiked into whole blood drawn into a CellSave tube. For initial assay development, mouse whole blood was used and results reproduced subsequently with human whole blood from healthy subjects. The spiked tumor cells in blood samples were recovered using the CellCapture™ Mouse/Rat CTC kit (for mouse blood) or CellSearch® CXC kit (for human blood), supplemented with the fluorescent dye (R- phycoerythrin) conjugated anti-cMET Ab. cMET in the recovered tumor cells was detected in the open/fourth channel on the CellTrack® Analyzer II®. Several proprietary and commercial cMET antibodies were screened for specificity and sensitivity. A commonly used commercially available cMET Ab (Santa Cruz Biotechnology C28) was not able to discriminate between cMET negative and positive cell lines. Results were confirmed by flow cytometry and by western blot analyses. optD11 was selected for CTC cMET expression assay development for the following reasons: a) ability to detect different cMET levels among positive cell lines (H441, MKN45, SNU5, SKOV3) while identifying SKBR3 as cMET negative; b) high affinity for cMET to allow for an image acquisition time of 0.02-0.04 second in the open channel; c) tolerance to the presence of LY2875358 (LA480), an experimental therapeutic anti-cMET Ab, allowing evaluation of cMET levels in CTCs post-treatment. The CTC assay for cMET expression, as well as a CTC assay measuring cMET gene amplification are currently being implemented in the early phase clinical studies for Lilly cMET inhibitors (JSBA, NCT01285037 & JTBA, NCT01287546). Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1738. doi:1538-7445.AM2012-1738

Abstract A49: Circulating tumor cell (CTC) assay development for detection of H2AX as a clinical pharmacodynamic (PD) marker for Chk1 kinase inhibitors.

Circulating tumor cells are prognostic of survival in metastatic breast, colon, and prostate cancers. Additionally, CTCs are of interest because they may be representative of the phenotype/genotype of the primary and metastatic tumors, and a useful tool (e.g. patient stratification) for drug development. CTCs, as “liquid biopsies” are potentially useful as a pharmacodynamic marker allowing easy repeat sampling before and after drug treatment. We describe the development of a CTC assay measuring H2AX induction, a marker of DNA damage. The CTC assay was developed using the FDA cleared Veridex/CellSearch™ instrument and reagents for enumeration of CTCs from blood. CellSearch defines CTCs as EpCam+/DAPI+/CK 8,18,19+/CD45−. For assay development, cells from tumor cell lines representing major solid tumor types were chosen, cultured, treated with inhibitors of checkpoint kinase 1 (Chk1, LY2603618, LY2606368) or with various standard-of-care (SOC) chemotherapeutics. These treated cells were then spiked into whole blood drawn into CellSave™ (preservative+EDTA). LY2603618 and LY2606368 are inhibitors of Chk1 kinase currently in clinical development. LY2603618 is meant to be used in combination with a DNA damaging agent, while LY2606368 has potent single agent activity. Inhibition of Chk1 in cells with DNA damage allows the cells to progress into mitosis without DNA repair, leading to cell death. In tumor xenograft mouse models, treatment reduced tumor volume with elevation of γH2AX in tumors and anagen hair follicles at drug exposure levels similar to concentrations used for the CTC γH2AX development assay. For initial assay development, mouse whole blood was used and results reproduced subsequently with human whole blood from healthy subjects. The spiked tumor cells in blood samples were recovered using the CellSearch Mouse/Rat CTC kit (for mouse blood) or human CXC kit (for human blood), supplemented with the R-PE conjugated anti-γH2AX antibody. γH2AX in the recovered tumor cells was detected in the open/fourth channel on the CellSearch instrument. Results were confirmed by flow analysis. Without drug treatment, only about 0.2–2% of all cultured tumor cells were γH2AX positive. The magnitude of the induction of γH2AX in the cells after treatment was dose and cell-line dependent. Significant induction of H2AX (>20% cells) was observed after 24 hour treatment with only a few SOC agents (cisplatin, etoposide) in sensitive tumor cell lines; the majority induced moderate to low levels (usually Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr A49.