Angiogenesis inhibitor TNP-470 reduces human pancreatic cancer growth

In this study we investigated the effects of the angiogenesis inhibitor TNP-470 on human pancreatic cancer cells in vitro and in vivo. The action of TNP-470 on vascular endothelial growth factor (VEGF) was also assessed. In vitro human pancreatic cancer cells (MIAPaCa-2, AsPC-1, and Capan-1), and human umbilical vein endothelial cells (HUVEC) were exposed to increasing concentrations (1 pg/ml to 100 (μg/ml) of TNP-470. Cell proliferation was assessed after 3 days by cell count and MTT assay. In vivo, 5 Χ 10⁶ pancreatic cancer cells were injected subcutaneously into nude mice. Four weeks later, 1 mm³ fragments of the resulting tumors were implanted into the pancreas of other mice. Animals received either TNP-470 (30 mg/kg every other day) or vehicle subcutaneously for 14 weeks. The volume of the primary tumor and metastatic spread were determined at autopsy. Concentrations of VEGF were determined in serum (VEGF_S) and ascites (VEGF_A) by enzyme-linked immunosorbent assay. Microvessel density was analyzed by immunohistochemistry in CD31 -stained tumor sections. In vitro, proliferation and viability of the human pancreatic cancer cell lines were significantly inhibited at high concentrations of TNP-470 (>1 μg/ml). In contrast, TNP-470 effectively decreased the growth of HUVEC at 100 pg/ml. In vivo, tumor volume and dissemination scores were significantly lower in all three pancreatic cancer cell lines. VEGF_S and VEGF_A were not different between treated groups. Treatment with TNP-470 significantly reduced neoangiogenesis in tumors of all three human pancreatic cancer cell lines: MIAPaCa-2 = 74.8 ±7.8/0.74 mm² vs. 24.8 ±3.7/0.74 mm²; AsPC-1 = 65.3 ±5.0/0.74 mm² vs. 26.0 ±3.4/0.74 mm²; and Capan-1 = 82.2 ±5.8/0.74 mm² vs. 26.9 ±2.5/0.74 mm² (P <0.001). However, survival was not statistically different between groups. TNP-470 reduced tumor growth and metastatic spread of pancreatic cancer in vivo. This was probably due to the antiproliferative effect of the agent on endothelial cells rather than to the direct inhibition of pancreatic cancer cell growth. TNP-470 activity was not associated with alteration of VEGF secretion. Supported by the R.S. Hirshberg Foundation and the Deutsche Forschungsgemeinschaft (grant HO 1843-1). Presented at the Forty-First Annual Meeting of The Society for Surgery of the Alimentary Tract, San Diego, Calif., May 21–24, 2000.