Carcinoembryonic antigen as a target for specific antitumor immunotherapy of head and neck cancer.

Human carcinoembryonic antigen (CEA) is an oncofetal glycoprotein overexpression of which by gastrointestinal carcinomas is well known. Expression of CEA in head and neck cancer (HNC) is not widely recognized. It is important to note that most of these studies used polyclonal antibodies that may have cross-reactivity with CEA-related antigens. Currently, CEA is being evaluated in preclinical and clinical studies as a target for specific immunotherapy against gastrointestinal adenocarcinomas that express the antigen. This study was conducted to evaluate CEA as a potential target for specific immunotherapy against HNC. Immunohistochemical analysis of tumor tissue from 69 cases of squamous cell carcinoma (SCC) of the head and neck using a CEA-specific monoclonal antibody (COL-1) showed the majority to be positive for CEA. Tumor cell lines derived from human HNC were screened for CEA transcripts using nested reverse transcription-PCR. Constitutive expression of CEA mRNA was detected in 7 of 10 HNC lines. CEA protein was detectable in lysates from all 7 of the lines by quantitative fluoroimmunometry. SDS-PAGE/Western blot analysis of cell lysates from these lines showed a COL-1 immunoreactive product with a molecular weight equivalent to that of CEA. Cell surface expression of CEA was low for the SCC lines; however, there was moderate to strong cytoplasmic staining intensity for all of the CEA(+) HNC lines by immunocytochemistry. Additional supportive evidence for CEA as a target was demonstrated by the presence of cytolytic activity of an HLA-A2-restricted/CEA-epitope-specific human CTL against a CEA-overexpressing HNC-derived SCC line. These results suggest that CEA may be considered as a possible target for specific vaccine-mediated immunotherapy against HNCs.