Introduction: Surgical therapy remains the only curative option for pancreatic ductal adenocarcinoma. But even after complete resection, almost all patients suffer from local tumor recurrence. Current standard adjuvant therapy with gemcitabine does not impressively affect the recurrence rate. The aim of this study was to evaluate a novel anti-angiogenic adjuvant treatment strategy by targeting the vascular endothelial growth factor receptor (VEGFR). We assayed the effects of a novel VEGFR inhibitor (ZK261991) on pancreatic carcinoma. ZK261991 is a highly selective and potent VEGFR-kinase inhibitor, which is orally available.
Methods: We used a previously established nude mouse orthotopic pancreatic cancer resection model. Subcutaneous donor tumor fragments (1 mm(3)) derived from human pancreatic cancer cell lines HPAF-2 and AsPC-1 were implanted in the pancreatic tail of 48 nude mice. Fourteen days afterwards, all mice underwent a histologically confirmed curative tumor resection followed by daily adjuvant oral therapy with ZK261991 (50 mg/kg; n = 24) vs. placebo (n = 24). The mice were sacrificed after 12 weeks of therapy or in case of defined endpoints. All sacrificed mice underwent autopsy. A dissemination score (local and systemic tumor spread), size of recurrent tumor mass, survival, and weight loss/gain were surveyed.
Results: Kaplan-Meier analysis of survival showed a significant benefit for mice treated with ZK261991 after HPAF-2 tumor resection: 83.8 days (95% CI 73.9-93.6) vs. 60.9 days (95% CI 48.9-73.0), p = 0.006. Adjuvant treatment with ZK261991 of AsPC-1-derived tumors showed a tendency towards a benefit compared to control but no significant difference: 75.8 days (95% CI 59.7-91.9) vs. 65.7 days (95% CI 51.6-79.7). There were no significant differences in dissemination score and size of recurrent tumor mass between the treatment groups.
Conclusion: Adjuvant anti-angiogenic therapy with the novel VEGFR-inhibitor ZK261991 resulted in a significant survival benefit after curative tumor resection in a clinically relevant orthotopic animal model of pancreatic cancer. Combination of anti-angiogenic treatment with cytotoxic agents may further improve the results of adjuvant therapy.