Department of Medicine, Division of Hematology-Oncology, University of Miami Miller School of Medicine and Sylvester Comprehensive Cancer Center, Miami, Florida 33136, USA.
Cancer Res. 2010 Dec 15;70(24):10121-30. doi: 10.1158/0008-5472.CAN-10-1047.
NKG2D ligands link the innate and adapative immune response by activating the receptors expressed on effector cells of both the innate (NK) and adaptive immune systems (CD8(+) T cells). In this study, we explored the potential therapeutic utility of this intersection by fusing the murine NKG2D ligand Rae-1β to the 3' end of an anti-HER2 IgG3 antibody containing an intact Fc domain (anti-HER2 IgG3-Rae-1β), thereby targeting an NK cell activation signal to HER2+ breast tumor cells. The antitumor efficacy of this anti-HER2-Rae-1β fusion protein was examined in a mouse mammary tumor model engineered to express HER2 (EMT6-HER2 cells). We observed an enhanced cytotoxic response of NK effectors against EMT-HER2 cells in vitro. Mice implanted on one flank with EMT6-HER2 cells and contralaterally with control EMT6 cells exhibited rapid regression of EMT6-HER2 tumors but delayed regression of contralateral EMT6 tumors. IFNγ was implicated, given a lack of antitumor efficacy in IFNγ(-/-) mice. Depletion of either NK cells or CD8(+) T cells abrogated tumor growth inhibition, suggesting essential roles for each in the observed antitumor activity. Mice rejecting EMT6-HER2 tumors after anti-HER2-Rae-1β treatment showed markedly decreased tumor growth when rechallenged with EMT6-HER2 or EMT6 cells, whereas both EMT6 and EMT6-HER2 cells grew in control mice, indicating the development of an adaptive memory response. Our findings demonstrate that administration of an antibody-NKG2D ligand fusion protein can enhance innate and adaptive immune antitumor responses, also evoking additional nontargeted antigens to enhance the potential clinical utility of this approach.
NKG2D 配体通过激活先天（NK）和适应性免疫系统（CD8(+) T 细胞）效应细胞表达的受体，将先天免疫和适应性免疫反应联系起来。在这项研究中，我们通过将小鼠 NKG2D 配体 Rae-1β融合到含有完整 Fc 结构域的抗 HER2 IgG3 抗体的 3'端（抗 HER2 IgG3-Rae-1β），从而将 NK 细胞激活信号靶向到 HER2+乳腺癌细胞，探索了这一交汇点的潜在治疗用途。在一种表达 HER2 的小鼠乳腺肿瘤模型（EMT6-HER2 细胞）中，我们研究了这种抗 HER2-Rae-1β融合蛋白的抗肿瘤疗效。我们观察到 NK 效应细胞对 EMT-HER2 细胞的体外细胞毒性反应增强。将 EMT6-HER2 细胞单侧植入和对照 EMT6 细胞对侧植入的小鼠，快速消退 EMT6-HER2 肿瘤，但对侧 EMT6 肿瘤消退延迟。由于 IFNγ(-/-) 小鼠缺乏抗肿瘤疗效，因此 IFNγ 被牵连其中。NK 细胞或 CD8(+) T 细胞耗竭均可消除肿瘤生长抑制，表明在观察到的抗肿瘤活性中，每种细胞都发挥了重要作用。在用抗 HER2-Rae-1β 治疗后排斥 EMT6-HER2 肿瘤的小鼠，在再次用 EMT6-HER2 或 EMT6 细胞挑战时，肿瘤生长明显减少，而 EMT6 和 EMT6-HER2 细胞在对照小鼠中生长，表明适应性记忆反应的发展。我们的研究结果表明，给予抗体-NKG2D 配体融合蛋白可以增强先天和适应性免疫抗肿瘤反应，还可以引发额外的非靶向抗原，从而增强这种方法的潜在临床应用。
