mart-1-antigen and Colorectal-Neoplasms

The sentinel lymph nodes are the most likely site of nodal metastasis. Their focused analysis results in upstaging cancers, although the extra yield from a more intensive work-up is generally dominated by micrometastases and isolated tumor cells. Nodal staging is generally done to reflect systemic spread of solid tumors and guide treatment accordingly. However, in general, the two processes of haematogenous and lymphogenic spread are not causally interrelated, and the extrapolation from low-volume nodal involvement to systemic involvement and therapeutic consequences of this extrapolation are still under investigation.

Topics: Antigens, Neoplasm; Breast Neoplasms; Colorectal Neoplasms; Female; Humans; Immunohistochemistry; Lymph Nodes; Lymphatic Metastasis; MART-1 Antigen; Melanocytes; Melanoma; Neoplasm Proteins; Neoplasm Staging; Reverse Transcriptase Polymerase Chain Reaction; Sentinel Lymph Node Biopsy

The uptake and long-term cross-presentation of tumor Ag long peptides (LP) by dendritic cells (DC) make them attractive cancer vaccine candidates. However, it remains to be established whether LP can prime long-lived tumor-reactive CTL and whether other cell types are able to cross-present them. Using HLA-A2 healthy donor and melanoma patient-derived PBMC, we studied the in vitro cross-priming potential of Melan-A 16-40 LP bearing the HLA-A2-restricted epitope 26-35 or its analog 26-35(A27L) and compared it to the priming capacity of the short analog. We then addressed LP priming capacity in vivo using HLA-A2 mice. We also studied LP cross-presentation by monocyte-derived DC, plasmacytoid DC, monocytes, and B cells. We showed that the modified LP gave rise to high and sustained cross-presentation by monocyte-derived DC. This led to cross priming in vitro and in vivo and to expansion of long-lived tumor-reactive cytotoxic T cells. In contrast, the LP containing the natural 26-35 epitope primed specific T cells poorly, despite its long-lived cross-presentation, and T cells primed against the short analog were short-lived. We further showed that LP cross-presentation is restricted to monocytes and conventional DC. These results document for the first time, to our knowledge, the strong immunogenicity of a human tumor Ag LP. Of note, they underscore that this property is critically dependent on sufficient HLA binding affinity and/or TCR ligand potency of the cross-presented epitope. We conclude that LP fulfilling this requirement should be used as tumor vaccines, together with DC maturating agents, especially the Melan-A 16-40(A27L) LP, for the treatment of HLA-A2(+) melanoma patients.

Topics: Amino Acid Sequence; Animals; Cancer Vaccines; CD8-Positive T-Lymphocytes; Cell Line, Tumor; Cells, Cultured; Colorectal Neoplasms; Cross-Priming; Dendritic Cells; Epitopes, T-Lymphocyte; HLA-A2 Antigen; Humans; Immunodominant Epitopes; Lymphocyte Activation; MART-1 Antigen; Melanoma; Mice; Mice, Mutant Strains; Molecular Sequence Data; Monocytes; Peptide Fragments; T-Lymphocytes, Cytotoxic

The adjuvant activities of the human lymphocyte activation gene-3 (LAG-3) molecule have been evaluated in a human setting by investigating the ability of a soluble recombinant human LAG-3 protein (hLAG-3Ig) to enhance the in vitro induction of viral- and tumor-specific CTLs. We found that soluble human LAG-3 significantly sustained the generation and expansion of influenza matrix protein Melan-A/MART-1 and survivin-specific CD8+ T lymphocytes in peripheral blood mononuclear cells (PBMC) of both cancer patients and healthy donors, showing its ability to boost CD8+ T-cell memory response or to prime naive T cells in vitro. The peptide-specific T cells generated in the presence of hLAG-3Ig were endowed with cytotoxic activity and enhanced release of type 1 cytotoxic T (Tc1) cytokines and were able to recognize tumor cells expressing their nominal antigen. Phenotype and cytokine/chemokines produced by antigen-presenting cells (APC) of PBMCs exposed in vitro for 2 days to peptide and hLAG-3Ig indicate that the LAG-3-mediated adjuvant effect may depend on a direct activation of circulating APCs. Our data revealed the activity of hLAG-3Ig in inducing tumor-associated, antigen-specific CD8+ T-cell responses in a human setting and strongly support the conclusion that this recombinant protein is a potential candidate adjuvant for cancer vaccines.

Topics: Adjuvants, Immunologic; Animals; Antigen-Presenting Cells; Antigens, CD; Antigens, Neoplasm; CD8-Positive T-Lymphocytes; CHO Cells; Colorectal Neoplasms; Cricetinae; Cytokines; Epitopes, T-Lymphocyte; Humans; Immunoglobulin G; Interferon-gamma; Lymphocyte Activation; Lymphocyte Activation Gene 3 Protein; MART-1 Antigen; Melanoma; Neoplasm Proteins; Peptides; Recombinant Proteins; T-Lymphocytes, Cytotoxic