Effect of surgical trauma on epithelial cell adhesion molecule (GA-733) vaccine–induced tumor resistance

Background: Surgical trauma inhibits immune function. Our goal was to study the effect of surgical intervention on the development of the immune response to epithelial cell adhesion molecule (EpCAM [GA-733]), a tumor-associated protein used for vaccination in colon cancer. Methods: Recombinant GA-733 and monophosphoryl-lipid A (MPLA) were incorporated into biodegradable beads and implanted in the following groups of mice: control, insufflation, and laparotomy. After surgery, the mice were inoculated with GA-733–transfected C26 cells (C26-EpCAM). Plasma anti-GA733 IgG antibodies were detected in enzyme-linked immunoassay (ELISA). Killing specific to GA-733 was assayed by C26-EpCAM–killing assay. Results: The difference in tumor size between immunized and nonimmunized animals was statistically significant only in control mice (p < 0.05). Greater cytotoxic response to C26-GA733 developed in all immunized mice groups than in their respective controls. However, anti-GA733 IgG increased significantly in the control and insufflation groups, but not in the laparotomy group. Conclusions: Combined GA-733 vaccine allows reduction of tumor growth in control but not in surgically managed animals. This vaccine can induce a specific-cell and antibody-mediated immune response. Open surgery leads to a decreased antibody response to the GA-733 tumor vaccine.