Department of Immunology, Howard Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
Proc Natl Acad Sci U S A. 2010 Mar 2;107(9):4275-80. doi: 10.1073/pnas.0915174107. Epub 2010 Feb 16.
Vaccination with irradiated B16 melanoma cells expressing either GM-CSF (Gvax) or Flt3-ligand (Fvax) combined with antibody blockade of the negative T-cell costimulatory receptor cytotoxic T-lymphocyte antigen-4 (CTLA-4) promotes rejection of preimplanted tumors. Despite CTLA-4 blockade, T-cell proliferation and cytokine production can be inhibited by the interaction of programmed death-1 (PD-1) with its ligands PD-L1 and PD-L2 or by the interaction of PD-L1 with B7-1. Here, we show that the combination of CTLA-4 and PD-1 blockade is more than twice as effective as either alone in promoting the rejection of B16 melanomas in conjunction with Fvax. Adding alphaPD-L1 to this regimen results in rejection of 65% of preimplanted tumors vs. 10% with CTLA-4 blockade alone. Combination PD-1 and CTLA-4 blockade increases effector T-cell (Teff) infiltration, resulting in highly advantageous Teff-to-regulatory T-cell ratios with the tumor. The fraction of tumor-infiltrating Teffs expressing CTLA-4 and PD-1 increases, reflecting the proliferation and accumulation of cells that would otherwise be anergized. Combination blockade also synergistically increases Teff-to-myeloid-derived suppressor cell ratios within B16 melanomas. IFN-gamma production increases in both the tumor and vaccine draining lymph nodes, as does the frequency of IFN-gamma/TNF-alpha double-producing CD8(+) T cells within the tumor. These results suggest that combination blockade of the PD-1/PD-L1- and CTLA-4-negative costimulatory pathways allows tumor-specific T cells that would otherwise be inactivated to continue to expand and carry out effector functions, thereby shifting the tumor microenvironment from suppressive to inflammatory.
用表达 GM-CSF（Gvax）或 Flt3-ligand（Fvax）的辐照 B16 黑色素瘤细胞免疫接种，结合抗 CTLA-4（细胞毒性 T 淋巴细胞抗原 4）的负性 T 细胞共刺激受体抗体阻断，可促进植入前肿瘤的排斥。尽管阻断 CTLA-4，但 PD-1（程序性死亡-1）与其配体 PD-L1 和 PD-L2 的相互作用或 PD-L1 与 B7-1 的相互作用仍可抑制 T 细胞增殖和细胞因子产生。在这里，我们表明 CTLA-4 和 PD-1 阻断的联合作用比单独使用这两种方法更有效地促进 Fvax 联合 B16 黑色素瘤的排斥。将 alphaPD-L1 添加到该方案中可导致 65%的植入前肿瘤被排斥，而单独使用 CTLA-4 阻断则为 10%。组合 PD-1 和 CTLA-4 阻断增加效应 T 细胞（Teff）浸润，导致肿瘤内具有高度优势的 Teff 与调节性 T 细胞的比例。表达 CTLA-4 和 PD-1 的肿瘤浸润 Teffs 比例增加，反映了细胞的增殖和积累，否则这些细胞会被失活。组合阻断还协同增加 B16 黑色素瘤内 Teff 与髓源性抑制细胞的比例。肿瘤和疫苗引流淋巴结中的 IFN-γ产生增加，肿瘤内 IFN-γ/TNF-α双产生 CD8+T 细胞的频率也增加。这些结果表明，PD-1/PD-L1-和 CTLA-4 负性共刺激途径的联合阻断允许原本失活的肿瘤特异性 T 细胞继续扩增并发挥效应功能，从而将肿瘤微环境从抑制性转变为炎症性。
