A nine amino acid peptide fragment of carcinoembryonic antigen (CEA), a protein that is overexpressed in several cancer cell types, including gastrointestinal, breast, and non-small cell lung. Autologous vaccination with activated autologous dendritic cells (DC) or peripheral blood mononuclear cells (PBMC) which have been exposed to CEA peptide 1 in vitro may stimulate the host immune system to mount a cytotoxic T lymphocyte (CTL) response against tumor cells expressing CEA, thereby inhibiting tumor growth. Check foractive clinical trials using this agent.