Immunotherapy of cancer - Generation of CEA specific CTL using CEA peptide pulsed dendritic cells

Abstract

Antigen specific cytotoxic T lymphocytes (CTL) are being studied for their potential immunotherapeutic benefit in the treatment of cancer. Carcinoembryonic antigen (CEA) is an oncofetal protein best known for its overexpression in the majority of colorectal, gastric, pancreatic, non small cell lung, and breast carcinomas. We are using dendritic cells (DC) pulsed with the CEA CTL peptide epitope to generate CEA specific CTL. DC from HLA A2+ donors were isolated by culturing plastic adherent PBMC in GMCSF and IL4 for 7 days. As expected these DC expressed the relevant cell surface molecules including HLA DR, CD58, CD80, and CD86. The DC were strippped of their endogenous peptides, pulsed with the A2 restricted CEA peptide, irradiated and used to stimulate autologous CD8+ T cells in the presence of IL7. Using this approach we have been able to generate CEA specific CTL from the PBMC of breast and pancreatic carcinoma patients as well as normal donors. These CTL can lyse CEA peptide pulsed T2 targets as well as HLA A2+ tumor cells expressing the CEA antigen. This data is being used to support a phase I active immunotherapy clinical protocol using DC pulsed with CEA peptide to treat patients with metastatic malignancies expressing CEA.