Development of a metastatic model for human endometrial carcinoma using orthotopic implantation in nude-mice

EphA2 targeted chemotherapy using an antibody drug conjugate in endometrial carcinoma

PURPOSE

EphA2 overexpression is frequently observed in endometrial cancers and is predictive of poor clinical outcome. Here, we use an antibody drug conjugate (MEDI-547) composed of a fully human monoclonal antibody against both human and murine EphA2 (1C1) and the tubulin polymerization inhibitor monomethylauristatin F.

EXPERIMENTAL DESIGN

EphA2 expression was examined in endometrial cancer cell lines by Western blot. Specificity of MEDI-547 was examined by antibody degradation and internalization assays. Viability and apoptosis were investigated in endometrial cancer cell lines and orthotopic tumor models.

RESULTS

EphA2 was expressed in the Hec-1A and Ishikawa cells but was absent in the SPEC-2 cells. Antibody degradation and internalization assays showed that the antibody drug conjugate decreased EphA2 protein levels and was internalized in EphA2-positive cells (Hec-1A and Ishikawa). Moreover, in vitro cytotoxicity and apoptosis assays showed that the antibody drug conjugate decreased viability and increased apoptosis of Hec-1A and Ishikawa cells. In vivo therapy experiments in mouse orthotopic models with this antibody drug conjugate resulted in 86% to 88% growth inhibition (P < 0.001) in the orthotopic Hec-1A and Ishikawa models compared with controls. Moreover, the mice treated with this antibody drug conjugate had a lower incidence of distant metastasis compared with controls. The antitumor effects of the therapy were related to decreased proliferation and increased apoptosis of tumor and associated endothelial cells.

CONCLUSIONS

The preclinical data for endometrial cancer treatment using MEDI-547 show substantial antitumor activity.

Clinical and biological significance of vascular endothelial growth factor in endometrial cancer

PURPOSE

Vascular endothelial growth factor (VEGF) is critical for angiogenesis and tumor progression; however, its role in endometrial cancer is not fully known. Therefore, we examined the clinical and therapeutic significance of VEGF in endometrial carcinoma using patient samples and an endometrioid orthotopic mouse model.

EXPERIMENTAL DESIGN

Following Institutional Review Board approval, VEGF expression and microvessel density (MVD) counts were evaluated using immunohistochemistry in 111 invasive endometrioid endometrial cancers by two independent investigators. Results were correlated with clinicopathologic characteristics. For the animal model, Ishikawa or Hec-1A cancer cell lines were injected directly into the uterine horn. Therapy experiments with bevacizumab alone or in combination with docetaxel were done and samples were analyzed for markers of angiogenesis and proliferation.

RESULTS

Of 111 endometrial cancers, high expression of VEGF was seen in 56% of tumors. There was a strong correlation between VEGF expression and MVD (P < 0.001). On multivariate analysis, stage (P = 0.04), grade (P = 0.003), VEGF levels (P = 0.03), and MVD (P = 0.037) were independent predictors of shorter disease-specific survival. In the murine model, whereas docetaxel and bevacizumab alone resulted in 61% to 77% tumor growth inhibition over controls, combination therapy had the greatest efficacy (85-97% inhibition over controls; P < 0.01) in both models. In treated tumors, combination therapy significantly reduced MVD counts (50-70% reduction over controls; P < 0.01) and percent proliferation (39% reduction over controls; P < 0.001).

CONCLUSIONS

Increased levels of VEGF and angiogenic markers are associated with poor outcome in endometrioid endometrial cancer patients. Using a novel orthotopic model of endometrioid endometrial cancer, we showed that combination of antivascular therapy with docetaxel is highly efficacious and should be considered for future clinical trials.

A murine model of bone marrow micrometastasis in breast cancer

Bone marrow (BM) is one of the most common sites and often the first clinical indication of metastatic progression of breast cancer. Multivariate analyses have shown that the presence of cytokeratin positive tumor cells in the marrow of women with newly diagnosed stage I, II or III breast cancer is an independent predictor of survival. The objective of this study was to develop an orthotopic model of spontaneous BM metastasis to facilitate studies of this process. A murine mammary adenocarcinoma cell line, Clone 66, was transduced with the neomycin resistance gene (Cl66neo) and injected orthotopically into female Balb/c mice. Polymerase chain reaction (PCR) for the neo gene performed on BM cells harvested from tumor bearing mice demonstrated as few as 10(2) injected tumor cells produced BM micrometastases at 4 weeks postinjection. Small foci of tumor cells were identified in the mammary fatpad (mfp) without gross evidence of primary tumors. Higher doses of tumor cells produced BM micrometastases, detectable by PCR, at one week post-injection. Constructs containing green fluorescent protein (GFP) and the neomycin resistance gene (neo) were also transduced into Clone 66 cells (Cl66-GFPneo) and injected into the mfp. GFP transduced tumor cells were identified in multiple tissues in addition to BM by flow cytometric analysis (FACS) but less 13% of the animals developed gross metastases. This model is a clinically relevant tool for the analysis of organ specificity of metastasis.

Metastasis from human breast cancer cell lines

Immunodeficient animals, principally nude mice, when used in appropriately designed studies have been shown to be useful for the experimental analysis of human breast cancer metastasis. As with many other human tumors, the implantation of breast cancer cells into an anatomically appropriate tissue (the mammary fatpad) results in increased tumor take and incidence of metastasis for certain cell lines compared with subcutaneous injection. Testing a number of widely available human breast cancer cell lines identified the MDA-MB-435 cell line as the most metastatic, producing lung and lymph node metastases in a high proportion of nude and severe combined immunodeficient (SCID) mice after injection in the mammary fatpad. Mixing human breast cancer cells with normal fibroblasts or with Matrigel also increases the tumor incidence and growth rates in nude mice. Different routes of injection can be used to assess the ability of human breast cancer cells to form metastatic lesions in the lungs (i.v. injection), the liver (injection in the spleen), the brain (direct or intracarotid artery injection) and the bone marrow and bone (injection into the left ventricle of the heart). These different approaches demonstrate the potential of experimental studies of human breast cancer growth and metastasis using immunodeficient mice; this model is valuable for experiments that test the role of metastasis-associated genes and the efficacy of novel forms of therapy.