Karen Coffman

The receptor tyrosine kinase EphA2 promotes mammary adenocarcinoma tumorigenesis and metastatic progression in mice by amplifying ErbB2 signaling

Overexpression of the receptor tyrosine kinase EPH receptor A2 (EphA2) is commonly observed in aggressive breast cancer and correlates with a poor prognosis. However, while EphA2 has been reported to enhance tumorigenesis, proliferation, and MAPK activation in several model systems, other studies suggest that EphA2 activation diminishes these processes and inhibits the activity of MAPK upon ligand stimulation. In this study, we eliminated EphA2 expression in 2 transgenic mouse models of mammary carcinoma. EphA2 deficiency impaired tumor initiation and metastatic progression in mice overexpressing ErbB2 (also known as Neu) in the mammary epithelium (MMTV-Neu mice), but not in mice overexpressing the polyomavirus middle T antigen in mammary epithelium (MMTV-PyV-mT mice). Histologic and ex vivo analyses of MMTV-Neu mouse mammary epithelium indicated that EphA2 enhanced tumor proliferation and motility. Biochemical analyses revealed that EphA2 formed a complex with ErbB2 in human and murine breast carcinoma cells, resulting in enhanced activation of Ras-MAPK signaling and RhoA GTPase. Additionally, MMTV-Neu, but not MMTV-PyV-mT, tumors were sensitive to therapeutic inhibition of EphA2. These data suggest that EphA2 cooperates with ErbB2 to promote tumor progression in mice and may provide a novel therapeutic target for ErbB2-dependent tumors in humans. Moreover, EphA2 function in tumor progression appeared to depend on oncogene context, an important consideration for the application of therapies targeting EphA2.

MEDI3617, a human anti-Angiopoietin 2 monoclonal antibody, inhibits angiogenesis and tumor growth in human tumor xenograft models

Angiopoietin 2 (Ang2) is an important regulator of angiogenesis, blood vessel maturation and integrity of the vascular endothelium. The correlation between the dynamic expression of Ang2 in tumors with regions of high angiogenic activity and a poor prognosis in many tumor types makes Ang2 an ideal drug target. We have generated MEDI3617, a human anti-Ang2 monoclonal antibody that neutralizes Ang2 by preventing its binding to the Tie2 receptor in vitro, and inhibits angiogenesis and tumor growth in vivo. Treatment of mice with MEDI3617 resulted in inhibition of angiogenesis in several mouse models including: FGF2-induced angiogenesis in a basement extract plug model, tumor and retinal angiogenesis. In xenograft tumor models, treatment with MEDI3617 resulted in a reduction in tumor angiogenesis and an increase in tumor hypoxia. The administration of MEDI3617 as a single agent to mice bearing human tumor xenografts resulted in tumor growth inhibition against a broad spectrum of tumor types. Combining MEDI3617 with chemotherapy or bevacizumab resulted in a delay in tumor growth and no body weight loss was observed in the combination groups. These results, combined with pharmacodynamic studies, demonstrate that treatment of tumor-bearing mice with MEDI3617 significantly inhibited tumor growth as a single agent by blocking tumor angiogenesis. Together, these data show that MEDI3617 is a robust antiangiogenic agent and support the clinical evaluation and biomarker development of MEDI3617 in cancer patients.

Clinical and biological impact of EphA2 overexpression and angiogenesis in endometrial cancer.

OBJECTIVE. EphA2 overexpression predicts poor prognosis in endometrial cancer. To explore mechanisms for this association and assess its potential as therapeutic target, the relationship of EphA2 expression to markers of angiogenesis was examined using patient samples and an orthotopic mouse model of uterine cancer. EXPERIMENTAL DESIGN. Expression of EphA2, estrogen receptor (ER), progesterone receptor (PR), Ki-67, vascular endothelial growth factor (VEGF) and microvessel density (MVD) was evaluated using immunohistochemistry in 85 endometrioid endometrial adenocarcinomas (EEC) by two independent investigators. Results were correlated with clinicopathological characteristics. The effect of EphA2- agonist monoclonal antibody EA5, alone or in combination with docetaxel was studied in vitro and in vivo. Samples were analyzed for markers of angiogenesis, proliferation and apoptosis. RESULTS. Of 85 EEC samples, EphA2 was overexpressed in 47% of tumors and was significantly associated with high VEGF expression (p=0.001) and high MVD counts (p=0.02). High EphA2 expression, high VEGF expression and high MVD counts were significantly associated with shorter disease-specific survival. EA5 led to decrease in EphA2 expression and phosphorylation in vitro. In the murine model, while EA5 (33-88%) and docetaxel (23-55%) individually led to tumor inhibition over controls, combination therapy had the greatest efficacy (78-92%, p<0.001). In treated tumors, combination therapy resulted in significant reduction in MVD counts, percent proliferation and apoptosis over controls. CONCLUSIONS. EphA2 overexpression is associated with markers of angiogenesis and is predictive of poor clinical outcome. EphA2 targeted therapy reduces angiogenesis and tumor growth in orthotopic uterine cancer models and should be considered for future clinical trials.

Antitumor efficacy of IPI-504, a selective heat shock protein 90 inhibitor against human epidermal growth factor receptor 2–positive human xenograft models as a single agent and in combination with trastuzumab or lapatinib

IPI-504 is a novel, highly soluble small-molecule inhibitor of heat shock protein 90 (Hsp90), a protein chaperone essential for regulating homeostasis of oncoproteins and cell signaling proteins. Human epidermal growth factor receptor 2 (HER2; ErbB2) oncoprotein, expressed in a subset of metastatic breast cancers, is a Hsp90 client protein. In this study, we investigated the antitumor activity and the mechanism of action of IPI-504 in HER2+, trastuzumab-sensitive and trastuzumab-refractory cell lines in vitro and in vivo. IPI-504 exhibited potent antiproliferative activities (range of IC50, 10-40 nmol/L) against several tumor cell lines examined, whereby mechanism of action was mediated through HER2 and Akt degradation. Both intravenous and oral administration of IPI-504 assessed in multiple schedules showed potent tumor growth inhibition in vivo with corresponding degradation of HER2. The tolerability and efficacy of IPI-504 combined with either trastuzumab or lapatinib were also investigated in HER2+ tumor xenograft models. Combination of IPI-504 with trastuzumab significantly enhanced tumor growth delay and induced greater responses when compared with either agent alone. Although, as expected, trastuzumab alone did not exhibit any significant antitumor activity in the trastuzumab-resistant JIMT-1 model, IPI-504 administered in combination with trastuzumab yielded greater antitumor efficacy than either agent alone. Finally, combination of IPI-504 and lapatinib was well tolerated up to 50 mg/kg IPI-504 and 100 mg/kg lapatinib and resulted in significant delay in tumor growth, including partial and complete tumor responses. These lines of evidence support the development of IPI-504 in HER2-positive breast cancers as a single agent and in combination with either trastuzumab or lapatinib.[Mol Cancer Ther 2009;8(8):2131–41]

Insertion of scFv into the hinge domain of full-length IgG1 monoclonal antibody results in tetravalent bispecific molecule with robust properties.

ABSTRACT By simultaneous binding two disease mediators, bispecific antibodies offer the opportunity to broaden the utility of antibody-based therapies. Herein, we describe the design and characterization of Bs4Ab, an innovative and generic bispecific tetravalent antibody platform. The Bs4Ab format comprises a full-length IgG1 monoclonal antibody with a scFv inserted into the hinge domain. The Bs4Ab design demonstrates robust manufacturability as evidenced by MEDI3902, which is currently in clinical development. To further demonstrate the applicability of the Bs4Ab technology, we describe the molecular engineering, biochemical, biophysical, and in vivo characterization of a bispecific tetravalent Bs4Ab that, by simultaneously binding vascular endothelial growth factor and angiopoietin-2, inhibits their function. We also demonstrate that the Bs4Ab platform allows Fc-engineering similar to that achieved with IgG1 antibodies, such as mutations to extend half-life or modulate effector functions.

Abstract 427: Host and tumoral CXCR2 signaling contributes to tumor growth

Chemokines are essential mediators of leukocyte migration and inflammation. Additionally they play an important role in tumour growth. The G-protein coupled receptor, CXCR2, and its ligands (CXCL 1,2,3,5,6,7 and IL8) have been shown to promote tumour initiation and growth, chemo-resistance, angiogenesis and immune cell infiltration (neutrophil, myeloid derived suppressor cells (MDSCs) and macrophages) into the tumour microenvironment. However the contribution of host and tumour CXCR2 has not been elucidated. We have developed both murine and human specific anti-CXCR2 antibodies alongside a humanised CXCR2 transgenic mouse to address the contribution of host and tumour CXCR2 signalling to tumour growth and maintenance. In pre-clinical tumours, granulocytic cells (neutrophils and MDSCs) within the tumour increase with size, in parallel with alteration in cell numbers observed within the spleen, peripheral blood and bone marrow. Inhibition of host CXCR2 has a dramatic impact on peripheral neutrophil levels, as well as their ability to become activated. In pre-clinical tumour models, inhibition of CXCR2 results in tumour growth inhibition. Contribution of host or tumour cells to the effect of CXCR2 blockade was model dependent. In the EL4 murine lymphoma model, only inhibition of host/peripheral CXCR2 was able to impact tumour growth. Whereas, in other murine syngeneic models (CT26 and B16), both host and tumour CXCR2 play a role in tumour growth. This was further demonstrated in an NSCLC patient derived xenograft, where the contribution of tumour CXCR2 was stronger than the host. Collectively our data show that CXCR2 inhibition (alone or in combination) has potential to influence growth of a number of tumour types. Future work is focused on understanding the mechanisms underlying the effects of CXCR2 inhibition, which remain key to developing it as an effective anti-cancer therapeutic. Citation Format: Danielle Carroll, James Harper, Karen McDaid, Ruth Franks, Catherine Eberline, Jane Kendrew, Richard Sainson, Judith Anderton, Chris Rossant, Karen Coffman, Ching Ching Leow, Ivan Inigo, Mitchell Reville, Jacintha Shenton, Lesley Young, Simon Barry. Host and tumoral CXCR2 signaling contributes to tumor growth. [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 427. doi:10.1158/1538-7445.AM2015-427

Abstract 1364: Combination of MEDI3617, a fully human anti-angiopoietin 2 monoclonal antibody, with inhibitors of the VEGF pathway enhances antitumor activity in vivo

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Angiopoietin 2 (Ang2) is an important regulator of angiogenesis, blood vessel maturation, and maintenance of the integrity of the vascular endothelium. Ang2-Tie2 interactions for vascular remodeling have been shown to play an important role in tumor vessel plasticity. MEDI3617 is a fully human anti-Ang2 monoclonal antibody that neutralizes the activity of Ang2, thereby inhibiting Ang2 from binding and signaling through the Tie2 receptor. Previously, we have demonstrated that treatment with MEDI3617 resulted in tumor growth inhibition in a wide spectrum of subcutaneous human tumor xenograft models. Given that angiogenesis is a process that requires concerted interplay of mutiple pathways, predominantly the VEGF pathway and the Ang/Tie pathway, we hypothesized that maximal inhibition of tumoral angiogenesis and consequently tumor growth could be achieved by blocking both pathways. We investigated the activity and tolerability of combining MEDI3617 with inhibitors of the VEGF pathway such as sorafenib and bevacizumab. In PLCPRF/5, a hepatocellular carcinoma xenograft model, combination of MEDI3617 and sorafenib resulted in a significant increase tumor growth inhibition. Similarly, in HPAC, a pancreatic cancer xenograft model, combination of MEDI3617 and bevacizumab resulted in greater tumor growth inhibition than either single agent alone. Mice exhibited no adverse effects or wt. loss following combination treatments. Taken together, these data support the clinical evaluation of the combination treatment of MEDI3617 and a VEGF inhibitor in cancer patients. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1364.