Vascular endothelial growth factor monoclonal antibody inhibits growth of anaplastic thyroid cancer xenografts in nude mice

Background: Anaplastic thyroid cancer (ATC) does not respond well to any treatment and is one of the most aggressive of all human cancers. Based on the importance of angiogenesis in solid tumor growth, we hypothesized that angiogenic blockade might reduce the growth of ATC. Methods: We tested the in vivo effect of vascular endothelial growth factor monoclonal antibody (VEGF-mAb) and thalidomide against ATC (ARO-81) xenografts in nude mice. Mice were injected subcutaneously with 1 × 10⁶ ARO-81 cells, allowed to implant (1 week), and then given daily intraperitoneal injections of vehicle (control; n = 9), VEGF-mAb μ/d; n = 9), or thalidomide (200 mg/kg per day; n = 9). Tumors were removed, sectioned, and stained for routine histology and immunohistochemistry. Results: At 6 weeks, VEGF-mAb-treated tumors were smaller (1603 ± 296 mm³) than either the thalidomide-treated (6007 ± 1498 mm³; p = 0.008) or the control groups (4040 ± 831 mm³; p = 0.014) and the VEGF-mAb-treated animals maintained greater weight (30.4 ± 0.84 g at week 6 versus thalidomide-treated, 26.0 ± 0.94 g, p = 0.003; and control, 25.8 ± 0.78 g, p = 0.001 animals). Central necrosis was observed in 3 of 9 VEGF-mAb-treated confidence interval (33%; 95% [CI] = 0.12-0.65) but in none of the control or thalidomide-treated tumors (0/18 total; 95% CI = 0.0-0.30; p = 0.029). VEGF staining intensity for VEGF-mAb- (2.0 ± 0.24; p = 0.012) and thalidomide- (2.1 ± 0.05; p = 0.052) treated tumors was greater than control (0.89 ± 0.31) as was p53 staining grade (VEGF-mAb [1.3 ± 0.37; p = 0.012]; thalidomide [1.0 ± 0.41; p = 0.05]; and controls [0.11 ± 0.11]). Conclusion: We conclude that systemic VEGF-mAb significantly reduces growth of ATC xenografts and is associated with increased VEGF and p53 expression. Thalidomide has no effect on tumor growth, but is also associated with increased VEGF and p53 expression. These observations provide the first evidence that VEGF-mAb-induced angiogenesis blockade may be of use for the treatment of ATC.