Immunization of metastatic breast cancer patients with CD80-modified breast cancer cells and GM-CSF.

Tumor-assocla,ted antigens have been identified on a variety of human neoplasms. Each of these antigens may be able to serve as a target for an immune respOf.lse, the result of which would be eliminatjon of the tumor celL An essential component of this immune response is the presentation of antigen to potential effector cells. This can be accom­ plished via host professional antigen~presenting cells (APe)! such as dendritic cells, or via the tumor itself. The lack of information about tumor~associated antigens and their appar­ ent lack of immunogenicity in vivo complicate the induction of immune responses against breast cancers. We have undertaken the effort to increase the antigen-presenting cell (APe) function of a breast cancer line that expresses at least one tumor-associated anti­ gen, Her2/neu. The her2/neu gene encodes a ] 85-kd transmembrane tyrosine kinase recep­ tor that shares homology with the epidermal growth factor receptor. Previous studies indicated that Her2ineu was overexpressed by 20-30%1 of breast and ovarian tumors and its overexpression has been associated with a poor prognosis [1,2]. Studies have a)so sug­ gested that Her2/neu can also function as a tumor-associated antigen. Cytotoxic T lympho­ cytes (CTL) isolated from ovarian tumors specifically recognizes Her2lneu-derived peptides and can kill Her2!neu+ tumors but not Her2!neutumors [3, 4]. Antibodies to