Concurrent cetuximab and bevacizumab therapy in a murine orthotopic model of anaplastic thyroid carcinoma.

OBJECTIVE: To evaluate the therapeutic efficacy of bevacizumab and cetuximab, alone and in combination, in an orthotopic model of anaplastic thyroid carcinoma (ATC) in athymic nude mice. STUDY DESIGN AND SETTING: This was a randomized, controlled in vivo study. MATERIALS AND METHODS: The ATC cell line, ARO, was used to establish orthotopic xenografts of ATC in athymic nude mice. Mice were randomized to therapy for 4 weeks in one of four treatment groups: placebo, cetuximab, bevacizumab, or the combination of cetuximab and bevacizumab. A second study compared the antitumor efficacy of the cetuximab-bevacizumab combination with doxorubicin. In both studies, tumor volumes on completion were measured and compared. Immunohistochemical analysis was performed with antiCD31 and antiproliferating cell nuclear antigen (PCNA) antibodies to assess the in vivo mechanisms of action of these agents. RESULTS: Cetuximab decreased the production of vascular endothelial growth factor by ATC cell lines in vitro. Mean tumor volumes for the control, bevacizumab, cetuximab, and combination groups at the end of the in vivo study were 291, 213, 94, and 42 mm(3), respectively. The differences in mean tumor volume for the control versus treatment groups were statistically significant. Immunohistochemical analysis showed decreased microvessel density and PCNA positivity in the treatment groups. In the doxorubicin comparison study, mean tumor volumes for control, doxorubicin, and combination antibody treatment groups were 175, 162, and 22 mm(3), respectively. CONCLUSIONS: Cetuximab and bevacizumab alone and in combination inhibit tumor growth and angiogenesis in an in vivo model of ATC. Also, this therapy was superior to doxorubicin therapy.

An orthotopic model of anaplastic thyroid carcinoma in athymic nude mice.

PURPOSE: To develop an orthotopic model of anaplastic thyroid carcinoma (ATC) in athymic nude mice. EXPERIMENTAL DESIGN: Various thyroid carcinoma cell lines were injected into the thyroid gland of athymic nude mice to determine whether such injection was technically feasible. ATC cells were then injected into the thyroid gland or the subcutis of nude mice at various concentrations, and the mice were then followed for tumor development. The tumors were examined histopathologically for local invasion or regional or distant metastasis. RESULTS: Injection of tumor cells into the thyroid glands of nude mice was technically feasible and resulted in the formation of thyroid tumors. The ATC cell line DRO showed significantly higher tumorigenicity in the thyroid gland than in the subcutis. In contrast, oral squamous cell carcinoma cell line TU167 shows no significantly higher tumorigenicity in the thyroid gland than in the subcutis. ATC tumors established in the thyroid gland also produced symptomatic compression of the esophagus and the trachea. Local invasion of the larynx and trachea was as well as high rates of pulmonary metastasis were also observed. Immunohistochemical staining showed higher microvessel density as well as higher expression of vascular endothelial growth factor and interleukin-8 in the orthotopic thyroid tumors than in ectopic tumors. CONCLUSION: An orthotopic model of ATC in athymic nude mice was developed that closely recapitulates the clinical findings of human ATC. This model should facilitate the understanding of the pathogenesis of ATC and aid in the development of novel therapies against ATC.

Epidermal growth factor receptor blockade potentiates apoptosis mediated by Paclitaxel and leads to prolonged survival in a murine model of oral cancer.

PURPOSE: Because survival for patients with oral cancer has not improved over the past 25 years, new approaches for treatment are needed. Targeted molecular therapy against epidermal growth factor receptor (EGFR) has shown promise as an adjuvant therapy in preliminary studies in several solid tumors, including head and neck cancer. The objective of this study was to determine the efficacy of paclitaxel and PKI166, a novel inhibitor of EGFR, against oral cavity cancer. EXPERIMENTAL DESIGN AND RESULTS: JMAR human oral cancer cells were pretreated for 1 h with PKI166 and then stimulated with epidermal growth factor. EGFR-specific tyrosine kinase autophosphorylation measured by Western immunoblotting was inhibited by PKI166 in a dose-dependent fashion at all doses tested (0.01-1 micro M). Next, the induction of apoptosis in JMAR cells treated with paclitaxel (0.001 to 0.1 micro M) with or without PKI166 (0, 1, or 2 micro M) was determined using a propidium iodide assay. The addition of 2.0 micro M PKI166 significantly increased tumor cell death, shifting the amount of paclitaxel needed to induce apoptosis in 50% of cells from 0.1 to 0.001 micro M. These in vitro findings were confirmed using an orthotopic model of oral cancer. JMAR oral cancer cells were implanted into the tongues of nude mice. After lingual tumors developed, mice were randomized into four groups (n = 10): (a) oral PKI166 (100 mg/kg); (b) i.p. paclitaxel (200 micro g/wk); (c) PKI166 and paclitaxel; or (d) placebo. Mice treated with PKI166/paclitaxel demonstrated a significant increase in survival (P = 0.028). After necropsy, all tongue tumors were evaluated for apoptosis by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay. A greater apoptotic fraction of tumor cells was found in tumors of mice treated with paclitaxel and PKI166 as compared with the other treatment groups (136.4 versus 37.8; P = 0.016). CONCLUSIONS: Combination therapy with paclitaxel and PKI166 prolongs survival in an orthotopic preclinical model of tongue cancer by increasing programmed cell death of oral cancer.