RESUMO
Unresectable colorectal liver metastases are commonly treated with systemic chemotherapy (SCT). Clinical studies on the effect of additional systemic application of bevacizumab (BE), a monoclonal antibody directed against vascular endothelial growth factor, to SCT showed a slight increase of patient survival. Herein, we studied in a rat model of colorectal liver metastasis whether a locoregional application of oxaliplatin (OX) and BE via hepatic arterial infusion (HAI) is more effective to inhibit metastatic growth compared to systemic drug application. Ten days after implantation of CC531 colorectal cancer cells into the left liver lobe of WAG/Rij rats, animals underwent either HAI or systemic intravenous application of BE (5 mg/kg body weight), OX (85 mg/m(2) body surface) or a combination of both. Sham-treated animals received saline and served as controls. Tumor volume was measured at days 10 and 13 using three dimensional ultrasound. At day 13 tumor tissue was analyzed histologically and immunohistochemically. Systemic application of OX, BE or their combination did not affect tumor volume when compared to controls. In contrast, HAI of BE and particularly the combination of BE and OX significantly reduced tumor volume. In the tumor tissue this was associated with a decrease of vascularization and cell proliferation as well as an increase of cell apoptosis, as indicated by a decreased number of PECAM-1- and PCNA-positive cells and an increased number of cleaved caspase-3-positive cells. Locoregional administration of BE, particularly in combination with OX, enhances the inhibitory effect on hepatic metastatic growth compared to systemic application of the drugs.
