An antigen-targeted approach to adoptive transfer therapy of cancer

Previous attempts to treat human malignancies by adoptive transfer of tumor -specific CTLs have been limited by the difficulty of isolating T cells of defined antigen specificity. The recent development of MHC class I/antigeni c peptide tetrameric complexes that allow direct identification of antigen- specific T cells has opened new possibilities for the isolation and in vitr o expansion of tumor-specific T cells, In the present study, we have derive d polyclonal monospecific cell lines from circulating Melan-A-specific CTL precursors of HLA-A*0201(+) melanoma patients by combining stimulation with recently identified peptide analogues of the immunodominant epitope from t he melanoma-associated antigen Melan-A with staining with fluorescent HLA-A *0201/Melan-A peptide tetramers, In vitro expansion of antigen-specific CD8 (+) T cells was monitored by flow cytometry with the fluorescent tetramers and anti-CD8 monoclonal antibody. This analysis revealed that Melan-A 26-35 peptide analogues were much more efficient than the parental peptides in s timulating a rapid in vitro expansion of antigen-specific CD8(+) T cells, T hese cells were then isolated by tetramer-guided cell sorting and subsequen tly expanded in vitro by mitogen stimulation. The resulting polyclonal but monospecific CTLs fully cross-recognized the parental peptides and were abl e to efficiently lyse Melan-A expressing tumor cells, Altogether, these res ults pave the way to a molecularly defined approach to antigen-specific ado ptive transfer therapy of cancer.