W.H. Caselmann

Effective angiostatic treatment in a murine metastatic and orthotopic hepatoma model

Vascular endothelial growth factor (VEGF) activity is correlated with a progressive tumor disease in patients with hepatocellular carcinoma (HCC). In spite of the well‐recognized role of VEGF in HCC, there are few data available regarding therapeutic strategies to block VEGF activity. Therefore, we employed a recombinant adenoviral vector encoding a soluble dominant negative fragment of VEGF receptor 2 (Flk‐1), AdsFlk‐1, to control pre‐established murine orthotopic and metastatic hepatomas. Vector function was confirmed via reverse‐transcriptase polymerase chain reaction and ELISA, and angiostatic effects were analyzed in vitro and in vivo. Antitumoral effects of systemic AdsFlk‐1 application were studied in a subcutaneous and orthotopic Hepa129 HCC model. Cell supernatant containing the truncated form of Flk‐1 had no direct effect on cell proliferation of Hepa129 cells in vitro but reduced endothelial tube formation on matrigel matrix by approximately 80% in vitro. Endothelial‐like cell infiltration into matrigel plugs in vivo was also decreased by 80%. Systemic treatment of tumor‐bearing mice inhibited tumor growth by 84% compared with the corresponding control group within 16 days after vector application. Likewise, the survival rate was significantly improved in the AdsFlk‐1 group compared with control. Orthotopic tumor growth was reduced by 82%, and development of malignant ascites was also retarded. In conclusion, systemic adenoviral‐mediated gene transfer of an Flk‐1 fragment significantly inhibited tumor growth in orthotopic and metastatic murine HCC. The data support the value of VEGF blockade as an effective target for HCC treatment. (HEPATOLOGY 2005;41:1233–1240)

Antitumoral efficacy of adenoviral mediated gene transfer of angiostatin-like molecule in subcutaneously growing HEPA129 hepatomas in mice depends on the application modus

Introduction: Hepatocellular carcinomas (HCC) are regularly hypervascularized and therefore present a rationale aim for angiostatic antitumor therapy. We tested the effect of an intratumoral or systemic application of an angiostatic adenoviral vector encoding angiostatin-like molecule (AdKl-3) representing the first three kringle regions of plasminogen in subcutaneously growing HCC. Method: AdKl-3 had been constructed and tested for activity as described before. Systemic in viva activity was confirmed in Matrigel assay. HCC were established by S.C. injection of 1000 x lo3 Hepa cells in syngenie C3H-mice. When tumor sizes reached about 1.50 mm3 intratumoral treatment was initiated by injection of AdlacZ (0,5 x 10” pfu; n=13) or AdKl-3 (0,5 x 10” pfu; n=8), respectively. For systemic treatment vectors were administered intraperitoneally (10” pfu) when tumors reached about 50 mm3 in volume (AdlacZ, n=5; AdKl-3, n=6). Tumor growth and survival rate were assessed. Results: Intratumoral tumor growth was inhibited by AdKl-3 by about 60%. Although systemic administration of AdKl-3 reduced the endothelial cell-like infiltration into Matrigel plugs by about 50%, tumor growth was not inhibited in the AdKl-3 group (852 mm3 versus 757 mm3 in the control). Survival rates were neither improved by intratumoral nor by systemic administration of AdKl-3. Conclusion: Intratumoral but not systemic administration of gene transfer for angiostatin-like molecule resulted in significant inhibition of tumor growth in this tumor model. The lack of improvement in survival rate might be related to transient protein expression by first generation adenoviruses. I 743 INHIBITION OF TUMOR GROWTH BY USING AN ADENOVIRUS EXPRESSING THE DOMINANT NEGATIVE RECEPTOR FLK-1 IN A MURINE TUMOR MODELS