Appropriately stimulated antigen-specific CD8 T cells can cause tumor rejection in murine models. This has also been described in humans, where adoptively transferred TIL have induced tumor regressions in patients with malignant melanoma (MM). Among treated patients there was an association between tumor regression and the presence of gp100-specific T cells in adoptively transferred TIL. Furthermore, tumor regressions were observed in 42% of patients with metastatic MM receiving a gp100 peptide vaccine and IL-2. A majority of patients had an increase in peptide-specific T cells. This suggests that repeated immunizations of cancer patients with synthetic peptides might elicit potent tumor-antigen-specific T cells, a strategy that could translate into clinical benefit for high-risk patients with MM. However, there are competing ideas as to the best immunogen (peptide, protein, and whole tumor cell) as well as the best adjuvant (cytokines or dendritic ability to induce antigen-specific T cells. Thus, it is critical to have a reliable, easily performed assay to measure antigen-specific T cells. Direct visualization of specific peptide-binding T cells, using fluorescent TCR antigen ligands called tetramers, can now be performed. A flow cytometry-based assay, tetramers can be used on small numbers of PBL to monitor a large multi-center trial, which could test the hypothesis that the generation of antigen-specific CD8 T cells correlates with an improvement in survival. We propose a pilot study of 20 patients with intermediate-thickness MM in which we compare tetramers with ELISPOT, LDA and intracellular cytokine production to measure peptide-specific T cells.. Patients will receive a modified gp100 peptide that binds to HLA-A2 and has been shown to increase the frequency of peptide-specific T cells in patients with metastatic MM. An HPV16 viral peptide will be used as a control to compare its immunogenicity to that of the self-gp100 peptide. The determination of a reliable and convenient method to quantify peptide-specific T-cell expansion should facilitate the development of effective vaccine strategies for a variety of different cancers.
| Walker, Edwin B; Haley, Daniel; Petrausch, Ulf et al. (2008) Phenotype and functional characterization of long-term gp100-specific memory CD8+ T cells in disease-free melanoma patients before and after boosting immunization. Clin Cancer Res 14:5270-83 |
| Petrausch, Ulf; Haley, Daniel; Miller, William et al. (2006) Polychromatic flow cytometry: a rapid method for the reduction and analysis of complex multiparameter data. Cytometry A 69:1162-73 |
| Meijer, S L; Dols, A; Hu, H M et al. (2001) Immunological and molecular analysis of the sentinel lymph node: a potential approach to predict outcome, tailor therapy, and optimize parameters for tumor vaccine development. J Clin Pharmacol Suppl:81S-94S |
