PDF file - 76K, Ex vivo frequencies of cytokine-producing NY-ESO-1 157-165-specific CD8+ T cells before and after vaccination with either MHC class I peptide alone (arm 1), or both MHC class I and class II peptides (arm 2).
ARTICLE ABSTRACT
Although melanoma vaccines stimulate tumor antigen–specific CD8+ T cells, objective clinical responses are rarely observed. To investigate this discrepancy, we evaluated the character of vaccine-induced CD8+ T cells with regard to the inhibitory T-cell coreceptors PD-1 and Tim-3 in patients with metastatic melanoma who were administered tumor vaccines. The vaccines included incomplete Freund's adjuvant, CpG oligodeoxynucleotide (CpG), and the HLA-A2–restricted analog peptide NY-ESO-1 157-165V, either by itself or in combination with the pan-DR epitope NY-ESO-1 119-143. Both vaccines stimulated rapid tumor antigen–specific CD8+ T-cell responses detected ex vivo, however, tumor antigen–specific CD8+ T cells produced more IFN-γ and exhibited higher lytic function upon immunization with MHC class I and class II epitopes. Notably, the vast majority of vaccine-induced CD8+ T cells upregulated PD-1 and a minority also upregulated Tim-3. Levels of PD-1 and Tim-3 expression by vaccine-induced CD8+ T cells at the time of vaccine administration correlated inversely with their expansion in vivo. Dual blockade of PD-1 and Tim-3 enhanced the expansion and cytokine production of vaccine-induced CD8+ T cells in vitro. Collectively, our findings support the use of PD-1 and Tim-3 blockades with cancer vaccines to stimulate potent antitumor T-cell responses and increase the likelihood of clinical responses in patients with advanced melanoma. Cancer Res; 74(4); 1045–55. ©2013 AACR.
