Tumor growth suppression by a retroviral vector displaying scFv antibody to CEA and carrying the iNOS gene.

Background: In a recent in vitro study we demonstrated a specifically-targeted killing of CEA-expressing cells by a recombinant bifunctional retrovector displaying an scFv antibody to CEA and carrying the iNOS gene. In this study, we tested whether a gene therapy using the recombinant retrovirus could inhibit the growth of CEA-expressing tumors in mice.

Materials And Methods: SCID mice were inoculated s.c. on the back with CEA-expressing MKN-45 cells on day 0. The recombinant viral particles were injected into the inoculated sites on days 3, 5 and 7 and tumor size was measured every 5 days.

Results: The s.c. administration of the recombinant retrovirus produced a marked growth inhibition of MKN-45 tumors in SCID mice. When the actual tumor weights were measured 50 days after initiation of treatment, about 70% reduction was observed in the treated group as compared to the control groups.

Conclusion: This approach may also be applied to other tumor antigens expressed on cancer cells and is a step towards the cell specific suppression of tumorigenicity.