Kristan Meetze

Antitumor activity of MLN8054, an orally active small-molecule inhibitor of Aurora A kinase

Increased Aurora A expression occurs in a variety of human cancers and induces chromosomal abnormalities during mitosis associated with tumor initiation and progression. MLN8054 is a selective small-molecule Aurora A kinase inhibitor that has entered Phase I clinical trials for advanced solid tumors. MLN8054 inhibits recombinant Aurora A kinase activity in vitro and is selective for Aurora A over the family member Aurora B in cultured cells. MLN8054 treatment results in G2/M accumulation and spindle defects and inhibits proliferation in multiple cultured human tumor cells lines. Growth of human tumor xenografts in nude mice was dramatically inhibited after oral administration of MLN8054 at well tolerated doses. Moreover, the tumor growth inhibition was sustained after discontinuing MLN8054 treatment. In human tumor xenografts, MLN8054 induced mitotic accumulation and apoptosis, phenotypes consistent with inhibition of Aurora A. MLN8054 is a selective inhibitor of Aurora A kinase that robustly inhibits growth of human tumor xenografts and represents an attractive modality for therapeutic intervention of human cancers.

GP369, an FGFR2-IIIb specific antibody, exhibits potent antitumor activity against human cancers driven by activated FGFR2 signaling

Dysregulated fibroblast growth factor (FGF) signaling has been implicated in the pathogenesis of human cancers. Aberrant activation of FGF receptor 2 (FGFR2) signaling, through overexpression of FGFR2 and/or its ligands, mutations, and receptor amplification, has been found in a variety of human tumors. We generated monoclonal antibodies against the extracellular ligand-binding domain of FGFR2 to address the role of FGFR2 in tumorigenesis and to explore the potential of FGFR2 as a novel therapeutic target. We surveyed a broad panel of human cancer cell lines for the dysregulation of FGFR2 signaling and discovered that breast and gastric cancer cell lines harboring FGFR2 amplification predominantly express the IIIb isoform of the receptor. Therefore, we used an FGFR2-IIIb-specific antibody, GP369, to investigate the importance of FGFR2 signaling in vitro and in vivo. GP369 specifically and potently suppressed ligand-induced phosphorylation of FGFR2-IIIb and downstream signaling, as well as FGFR2-driven proliferation in vitro. The administration of GP369 in mice significantly inhibited the growth of human cancer xenografts harboring activated FGFR2 signaling. Our findings support the hypothesis that dysregulated FGFR2 signaling is one of the critical oncogenic pathways involved in the initiation and/or maintenance of tumors. Cancer patients with aberrantly activated/amplified FGFR2 signaling could potentially benefit from therapeutic intervention with FGFR2-targeting antibodies.

Neuregulin 1 Expression Is a Predictive Biomarker for Response to AV-203, an ERBB3 Inhibitory Antibody, in Human Tumor Models

Purpose: ERBB3 is overexpressed in a broad spectrum of human cancers, and its aberrant activation is associated with tumor pathogenesis and therapeutic resistance to various anticancer agents. Neuregulin 1 (NRG1) is the predominant ligand for ERBB3 and can promote the heterodimerization of ERBB3 with other ERBB family members, resulting in activation of multiple intracellular signaling pathways. AV-203 is a humanized IgG1/κ ERBB3 inhibitory antibody that completed a first-in-human phase I clinical trial in patients with advanced solid tumors. The purpose of this preclinical study was to identify potential biomarker(s) that may predict response to AV-203 treatment in the clinic. Experimental Design: We conducted in vivo efficacy studies using a broad panel of xenograft models representing a wide variety of human cancers. To identify biomarkers that can predict response to AV-203, the relationship between tumor growth inhibition (TGI) by AV-203 and the expression levels of ERBB3 and NRG1 were evaluated in these tumor models. Results: A significant correlation was observed between the levels of NRG1 expression and TGI by AV-203. In contrast, TGI was not correlated with ERBB3 expression. The correlation between the levels of NRG1 expression in tumors and their response to ERBB3 inhibition by AV-203 was further validated using patient-derived tumor explant models. Conclusions: NRG1 is a promising biomarker that can predict response to ERBB3 inhibition by AV-203 in preclinical human cancer models. NRG1 warrants further clinical evaluation and validation as a potential predictive biomarker of response to AV-203. Clin Cancer Res; 21(5); 1106–14. ©2014 AACR.

Abstract C173: Anti‐tumor activity of SCH 900105 (AV299), an anti‐HGF antibody, in non‐small cell lung cancer models

Hepatocyte growth factor (HGF) is the soluble ligand for the c‐Met receptor tyrosine kinase. Signaling through the HGF/c‐Met pathway mediates a plethora of cellular activities that are involved in cancer cell dysregulation, tumorigenesis, and metastasis including cell proliferation and survival, angiogenesis, migration, invasion and drug resistance. HGF/c‐Met autocrine and paracrine regulatory loops have been reported in a number of non‐small cell lung cancer studies. Furthermore, studies have shown that HGF/c‐Met pathway upregulation via either c‐Met amplification or HGF secretion can result in intrinsic or acquired resistance to EGFR TKIs in lung adenocarcinoma. SCH 900105, formerly known as AV‐299, is a humanized IgG1 antibody with high affinity to HGF that neutralizes all its biological functions tested with sub‐nM potency. It is currently in phase 1 clinical trials that demonstrated good safety and tolerability. Anti‐tumor activity of SCH 900105 was observed in HGF autocrine and paracrine in vivo tumor models, such as GMB, pancreatic cancer and multiple myeloma. Anti‐tumor efficacy of SCH 900105 was evaluated in paracrine models of the HGF‐dependent NCI‐H596 NSCLC cell line xenografted in SCID mice engineered to produce human HGF. In these models, SCH 900105 treatment resulted in dose‐dependent decrease in tumor growth with concurrent increases in serum and tumor concentration of SCH900105 and increases in serum SCH 900105/HGF complex. Treatment also led to significant reduction in phospho‐c‐Met and phospho‐Akt levels in tumor lysates. Concurrently, increases in cleaved caspase‐3 and decreases in Ki67 and CD31 staining were also observed. Anti‐tumor activity of SCH 900105 was also explored in combination with EGFR inhibitors, erlotinib and Cetuximab that resulted in increased efficacy. SCH900105 treatment resulted in decreased phospho‐c‐Met levels with concurrent increases in phospho‐EGFR levels. Conversely, erlotinib treatment decreased phospho‐EGFR with concurrent increases in phospho‐Met levels. The combination of SCH900105 with Cetuximab resulted in complete response in all animals treated without tumor re‐growth 50 days after treatment withdrawal. Potent anti‐tumor activity of SCH 900105 in combination with EGFR inhibitors observed in these preclinical models suggests testing the combination in NSCLC is warranted in the clinic. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C173.

Abstract C181: Preclinical efficacy and pharmacodynamics of SCH 900105 (AV‐299) an anti‐HGF antibody in an intracranial glioblastoma model

Hepatocyte growth factor (HGF) is a pluripotent growth factor produced predominantly by mesenchymal or stromal cells, and binds to the well‐characterized tyrosine kinase receptor, c‐Met. The HGF/c‐Met pathway is frequently deregulated in different types of human cancers and is thought to play an important role in regulating tumor growth, invasion, metastasis and drug resistance. HGF/c‐Met autocrine and paracrine loops have been reported in a number of human cancers including breast, lung, bladder, gastric, head and neck, glioma, multiple myeloma, leukemias, and certain sarcomas. SCH 900105, formerly known as AV‐299, is a potent, humanized anti‐HGF antibody. It is currently in phase 1 clinical trials that demonstrated good safety and tolerability. It has been shown to neutralize HGF binding to c‐Met and inhibits its biological function in vitro, such as cell signaling, growth, motility, invasion and drug resistance. SCH 900105 was also shown to have potent anti‐tumor activity in autocrine and paracrine GBM, NSCLC, pancreatic and multiple myeloma xenograft models both as monotherapy and in combinations with chemotherapeutics or targeted agents. In vivo efficacy of systemically administered SCH 900105 was evaluated in an intracranial autocrine U87MG model. In these studies, SCH 900105 treatment resulted in significant survival benefit over an IgG treated control group. Immunohistochemistry staining for SCH 900105 in the intracranial tumor tissue suggested adequate tumor penetration of the antibody. Treatment also led to significantly decreased tumor phospho‐c‐Met, increased cleaved caspase‐3, as well as decreased Ki67 and CD31 staining. Greater survival benefit was also seen when SCH 900105 was combined with temozolomide in U87 intracranial model. These findings suggest evaluating SCH 900105 in GBM is warranted. Citation Information: Mol Cancer Ther 2009;8(12 Suppl):C181.

Abstract 3674: Pentarins: Improved tumor targeting through nanoparticle encapsulation of miniaturized biologic drug conjugates

The specific targeting of cytotoxic drugs to solid tumors has achieved success with the advent of antibody drug conjugates (ADCs). This approach has had notable success but has also met with limitations. The most common issue limiting ADC effectiveness is believed to be low tumor permeation by these large (∼150 kDa) molecules. Attempts to address this limitation have been focused on the design of miniaturized biologic drug conjugates such as those with small protein or small molecule targeting moieties. However, these efforts uniformly result in conjugates with poor pharmacokinetics in contrast to the extended plasma pharmacokinetics observed with ADCs. The Pentarin platform encapsulates miniaturized biological drug conjugates within nanoparticles to improve the biodistribution of these classes of conjugates. There are multiple benefits to this strategy. Through the enhanced permeability and retention (EPR) effect the nanoparticles accumulate in the perivascular space of the tumor tissue. Next the nanoparticles release the permeable miniaturized conjugate that can penetrate in to the tumor, bind to an over-expressed target on the cancer cell surface, internalize the payload and elicit a strong biological effect. All of this is further enhanced by the extended plasma pharmacokinetics of the nanoparticle when compared to the conjugate alone. To exemplify the Pentarin platform we have designed novel miniaturized biologic drug conjugates to an over-expressed target found in small cell lung cancer. In vitro data has shown the designed conjugates specifically and potently target tumor cells expressing the receptor of interest. When encapsulated in nanoparticles, these miniaturized biologic drug conjugates have improved plasma pharmacokinetics, the amount of payload delivered to xenograft tumors is increased and the xenograft efficacy is significantly more pronounced over drug conjugate not in a nanoparticle. These observations correlate with in vivo mechanistic assays in the xenograft tissue. These data will be presented, together with the name of the target, to demonstrate the impact of the Pentarin platform and to show progress towards the first clinical candidate from this work. Citation Format: Mark T. Bilodeau, Rajesh Shinde, Brian White, Patrick Bazinet, Kerry Whalen, Michelle Dupont, Kristina Kriksciukaite, Jamie Quinn, Beata Sweryda-Krawiec, Rossitza Alargova, Adam Brockman, Patrick Lim Soo, Kristan Meetze, Benoit Moreau, Haley Oller, Mike Ramstack, Danielle Rockwood, Sukhjeet Singh, Tsun Au Yeung, Sudha Kadiyala, Craig Dunbar, Richard Wooster. Pentarins: Improved tumor targeting through nanoparticle encapsulation of miniaturized biologic drug conjugates. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3674. doi:10.1158/1538-7445.AM2015-3674

Abstract 2509: AV-203, a humanized ERBB3 inhibitory antibody inhibits ligand-dependent and ligand-independent ERBB3 signaling in vitro and in vivo

ERBB3 is a member of the EGFR receptor tyrosine kinase (RTK) family. Agents targeting the family of EGFR RTKs have become widely used for the treatment of lung, colon, breast, gastric, and head and neck cancers. Among EGFR family members, ERBB3 is of special interest because of its ability to activate the survival pathway driven by PI3K, its essential role in HER2 mediated cancers, and its involvement in tumor progression and drug resistance. The ERBB3 receptor is expressed on cells from cancers of the head and neck, lung, breast, ovaries, prostate, colon, pancreas, and gastrointestinal tract. Its expression is often linked to poor prognosis. In addition, it has been implicated in the development of resistance to current anti-cancer agents including receptor-targeted tyrosine kinase inhibitors (TKI). ERBB3 lacks detectable tyrosine kinase activity and its activation requires the heterodimerization of ERBB3 with RTK partners, i.e., HER2, EGFR or MET. ERBB3 recruitment in heterodimer complexes takes place when RTKs are overexpressed or amplified or stimulated by ligands, i.e. Neuregulin-1 (NRG1) or epidermal growth factor (EGF). Because of the lack of ERBB3 kinase activity, antibody therapies directed against the extracellular domain of ERBB3 seem to be the most effective method to disrupt the function of ERBB3. Herein, characterization of AV-203, a humanized ERBB3 inhibitory antibody, is presented. AV-203 is a humanized immunoglobulin G1/kappa antibody that targets the ERBB3 RTK. AV-203 binds to human ERBB3 with high affinity (KD = 76 pM at 37°C) characterized by fast association and slow dissociation rates. AV-203 also binds to cynomolgus monkey ERBB3 but not to mouse ERBB3, allowing toxicological assessment of the antibody in this species. AV-203 is a potent inhibitor of ERBB3 activation and its downstream signaling molecule AKT in response to both ligands, NRG1 and EGF. In ligand-independent settings, AV-203 inhibits the steady state activation of ERBB3/AKT which depends on the presence of an overexpressed RTK such as HER2. AV-203 can prevent the ERBB3/HER2 heterodimer formation and completely inhibit the proliferation in response to NRG1 ligand in human breast cancer cell line, MCF7. AV-203 down regulates ERBB3 receptor in vitro and in vivo. Finally, AV-203 inhibits tumor growth in a broad spectrum of xenograft models in which ERRB3 is activated by its ligand NRG1 or by HER2 overexpression such as the pancreatic cancer BxPC3 or the HER2 amplified breast cancer MDA-MB-453 xenograft models, respectively. In conclusion, AV-203 demonstrated high affinity binding to ERBB3, potent inhibition of NRG1 binding and of ERBB3 activation in ligand-dependent and ligand-independent manners both in vitro and in vivo. First in human trial of AV-203 in cancer patients is planned for 2012. 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 2509. doi:1538-7445.AM2012-2509

Novel Targeting of Transcription and Metabolism in Glioblastoma

Purpose: Glioblastoma (GBM) is highly resistant to treatment, largely due to disease heterogeneity and resistance mechanisms. We sought to investigate a promising drug that can inhibit multiple aspects of cancer cell survival mechanisms and become an effective therapeutic for GBM patients. Experimental Design: To investigate TG02, an agent with known penetration of the blood–brain barrier, we examined the effects as single agent and in combination with temozolomide, a commonly used chemotherapy in GBM. We used human GBM cells and a syngeneic mouse orthotopic GBM model, evaluating survival and the pharmacodynamics of TG02. Mechanistic studies included TG02-induced transcriptional regulation, apoptosis, and RNA sequencing in treated GBM cells as well as the investigation of mitochondrial and glycolytic function assays. Results: We demonstrated that TG02 inhibited cell proliferation, induced cell death, and synergized with temozolomide in GBM cells with different genetic background but not in astrocytes. TG02-induced cytotoxicity was blocked by the overexpression of phosphorylated CDK9, suggesting a CDK9-dependent cell killing. TG02 suppressed transcriptional progression of antiapoptotic proteins and induced apoptosis in GBM cells. We further demonstrated that TG02 caused mitochondrial dysfunction and glycolytic suppression and ultimately ATP depletion in GBM. A prolonged survival was observed in GBM mice receiving combined treatment of TG02 and temozolomide. The TG02-induced decrease of CDK9 phosphorylation was confirmed in the brain tumor tissue. Conclusions: TG02 inhibits multiple survival mechanisms and synergistically decreases energy production with temozolomide, representing a promising therapeutic strategy in GBM, currently under investigation in an ongoing clinical trial. Clin Cancer Res; 24(5); 1124–37. ©2017 AACR.

Abstract 4484: BTP-114: An albumin binding cisplatin prodrug with improved and sustained tumor growth inhibition

Platinum drugs have proven to be effective in treating cancer, for example >90% of men with testicular cancer are cured with a platinum therapeutic. Platinum drugs are also widely used for the adjuvant treatment of common cancers such as those of the lung, colon and ovary. However for the majority of tumor types the clinical response rates for platinum therapies are low, for example the 1 year survival rate for lung cancer patients treated with platinum therapeutics is ∼30%. The key limitations of the existing platinum therapies are the dose limiting toxicities that restrict dose and/or duration of therapy and the absence of personalization that targets the drugs to the patients most likely to benefit. To address these issues we have designed a novel prodrug of cisplatin, BTP-114. On infusion into the blood a maleimide group on BTP-114 covalently attaches to serum albumin. This prolongs the circulation of BTP-114 in plasma and alters the biodistribution of the compound. Importantly the dose of platinum can be increased and the amount of platinum that accumulated in xenograft tumor tissue and the amount of platinum bound to tumor DNA are both increased relative to cisplatin. An elevation of DNA damage in tumor cells in vivo is observed with BTP-114. Together the properties of BTP-114 result in pronounced and sustained tumor growth inhibition compared to cisplatin. In parallel to the discovery of BTP-114 we have explored potential biomarkers to predict which tumors are most likely to respond. These data will be presented towards developing BTP-114 as a personalized platinum medicine for cancer patients. BM and RA contributed equally to this work. Citation Format: Benoit Moreau, Rossitza Alargova, Adam Brockman, Kerry Whalen, Jamie Quinn, Kristan Meetze, Patrick Bazinet, Michelle DuPont, Beata Krawiec, Kristina Kriksciukaite, Charles Lemelin, Patrick LimSoo, Haley Oller, Mike Ramstack, Danielle Rockwood, Rajesh Shinde, Sukhjeet Singh, Brian White, Tsun AuYeung, Craig Dunbar, Mark Bilodeau, Richard Wooster. BTP-114: An albumin binding cisplatin prodrug with improved and sustained tumor growth inhibition. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4484. doi:10.1158/1538-7445.AM2015-4484

Abstract 644: Anti-tumor activities of antibodies targeting the RON receptor and a biomarker of response

RON is a receptor tyrosine kinase of the MET family. Stimulation by its ligand, Macrophage Stimulating Protein (MSP), activates a signaling cascade leading to cell growth, migration, invasion and resistance to apoptosis. In animal models, RON overexpression in breast and lung results in tumor growth and metastasis. RON receptor activation in animal models also play a role in tumor-host interactions such as osteolytic bone destruction and tumor associated macrophage infiltration. RON overexpression has been demonstrated in several solid tumors including pancreatic, breast, ovarian and colon. RON overexpression is correlated with disease progression and shorter survival in ovarian and colon cancer. Several isoforms of RON have been reported, including a potentially oncogenic form, RON Δ160 in CRC. Given the strong evidence for the involvement of RON in numerous aspects of tumor biology, investigating an anti-RON antibody as cancer therapy is warranted. We have identified and characterized a panel of antagonistic murine anti-human RON antibodies. Humanization of two antibodies resulted in Superhumanized™ anti-RON antibodies that are capable of inhibiting MSP dependent RON downstream signaling, cell migration and invasion in vitro. The anti-RON antibodies have subnanomolar binding affinity to wildtype RON and RON Δ160 receptors. The lead antibody is capable of internalizing and degrading the receptor in vitro and in vivo. The antibodies are capable of inhibiting growth of engineered murine models that are driven by wildtype or RON Δ160 receptor, as well as traditional human cancer xenografts. Given the complex role of RON in tumor biology, identification of response biomarkers is crucial for identifying the patient populations most likely to benefit from treatment. A multi-gene biomarker potentially predictive of tumor response to RON antibody, the RON pathway index, was tested and validated using a panel of human cancer cell line xenografts. Current results demonstrate a statistically significant correlation between the degree of tumor growth inhibition by anti-RON antibody treatment and RON pathway index value. Thus, we have identified a biomarker of tumor response to anti-RON antibody that can potentially help us identify tumor types or tumor subtypes of interest in the clinic. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 644. doi:10.1158/1538-7445.AM2011-644