A recombinant adenovirus vector encoding the light chain of human coagulation factor VII and IgG1 Fc fragment to targeting tissue factor for colorectal cancer immunotherapy in the mouse model

Abstract

Purpose: Over expression of tissue factor (TF) occurs in more than 50 % of colorectal cancer (CRC). Therefore, TF represents an attractive target antigen for immunotherapy in CRC.

Methods: Here, we assessed the safety and efficacy of a recombinant adenovirus vector encoding the light chain of human coagulation factor VII (hfVII-LC) and human IgG1 Fc fragment (hIgG1-Fc), termed "benc vector," by targeting TF in the mouse model with colon cancer. Benc vector was administered intravenously or intratumorally in SCID mice with TF over-expressing HT-29 colon cancer. The safety and efficacy of benc vector were observed during animal experiments.

Results: Complete inhibition of tumor growth (5/5) was observed not only in the intravenously injection of benc vector group but also in the intratumorally of benc vector group. We also observed a precautionary effect on lung metastases of HT-29 cells by intratumoral injection of benc vector. In the control group of animals given empty control vector, all animals (5/5) developed lung tumors and exhibited a higher number of nodules after injection with HT-29 cells via the tail vein. In contrast, only three animals (3/5) in the treatment group receiving benc vector had any observable lung metastases and a lower number of nodules. No animals died and no bleeding was observed both in treatment groups and control groups. Moreover, only moderate liver damage was detected in mice receiving benc vector by intravenous injections.

Conclusions: Benc vector encoding hfVII-LC and hIgG1-Fc can effectively inhibit tumor growth and metastases in SCID mice with TF over-expressing colon cancer and shows promise as an agent for CRC immunotherapy.

Fig. 1

Strong TF expression was found on tumor vascular endothelial cells (a) and tumor cells (b) in HT-29 colon cancer xenografts. Brown staining indicates positive cells. The presence of TF in colon cancer cells and control are shown after immunostaining with mAb to TF.TF expression was strongly positive in HT-29 colon cancer cells (c) and negative in the control (d). Strong pink staining indicates TF-positive cells. All photographs are shown at ×200 magnification

Fig. 2

a Schematic overview of benc vector. b Western blot using anti-hIgG 1-Fc mAb, culture supernatants, and lysates of 293A cells infected with Ad-hfVII-LC-hIgG 1-Fc plasmid showing a specific 62-kDa band corresponding to the hfVII–LC fusion pritein. Lane 1: protein marker (MBI, CA:SM0671, Canada); Lane 2: culture supernatants from 293A cells infected with Ad-hfVII-LC-hIgG 1-Fc plasmid; Lane 3: lysates of 293A cells infected with Ad-hfVII-LC-hIgG 1-Fc plasmid

Fig. 3

The effect of intratumoral benc vector injections on subcutaneous xenografts of HT-29 colon cancer in SCID mice. a Indicates tumor growth over time. b Indicates tumor weight at experiment end point

Fig. 4

The effect of intravenous benc vector injection on subcutaneous xenografts of HT-29 colon cancer cells in SCID mice. a Indicates tumor growth over time. b Indicates tumor weight at experiment end point

Fig. 5

Liver sections from SCID mice injected intratumorally with benc vector. a Injected with physiologic saline, liver cells were normal; b Injected intratumorally with 5 × 10¹⁰ IU of benc vector, liver cells were normal; c Injected intravenously with 2 × 1,011 benc vector, liver cells indicated dropsy and vacuolar degeneration. All photographs are shown at ×200 magnification