尽管在免疫疗法方面取得了一些进展，但许多非小细胞肺癌（NSCLC）患者对免疫检查点抑制剂（ICI）无反应。对ICI的耐药可能是由于抗肿瘤T淋巴细胞的亚优引发的，主要是由于抗原呈递不佳以及免疫抑制的肿瘤微环境（TME）对它们的排斥和损害。在最近的一项针对NSCLC患者的I期临床试验中，通过用工程化的分泌CCL21（CCL21-DC）的树突状细胞进行在体免疫接种（ISV），促进了T淋巴细胞的肿瘤浸润和PD-L1上调。我们采用不同的驱动突变（KrasG12D / P53 + / - / Lkb1- / -（KPL）; KrasG12D / P53 + / -（KP）; 和 KrasG12D（K））以及不同肿瘤突变负荷的NSCLC小鼠模型，在评估CCL21-DC ISV联合ICI的疗效方面进行了全面分析，其中CCL21-DC ISV使免疫抵抗性的小鼠NSCLC对ICI具有敏感性，并建立了针对肿瘤特异性免疫记忆。免疫表型分析揭示了CCL21-DC消除了肿瘤促进性中性粒细胞，促进了CD8溶解性和CD4 Th1淋巴细胞的持续浸润，并丰富了TME中的祖细胞T细胞。加入ICI到CCL21-DC进一步增强了局部和全身T细胞的扩张和效应功能。肿瘤突变谱的纵向评价揭示了CCL21-DC加ICI诱导的肿瘤亚克隆免疫编辑的现象，符合肿瘤特异性T细胞反应的扩大。CCL21-DC ISV与抗PD-1协同消除小鼠NSCLC。我们的数据支持在NSCLC患者中应用CCL21-DC ISV与检查点抑制的联合治疗。© 作者（或其雇主）2023年授权再利用(CC BY-NC）。不允许商业再利用。由BMJ出版。

Despite recent advances in immunotherapy, many patients with non-small cell lung cancer (NSCLC) do not respond to immune checkpoint inhibitors (ICI). Resistance to ICI may be driven by suboptimal priming of antitumor T lymphocytes due to poor antigen presentation as well as their exclusion and impairment by the immunosuppressive tumor microenvironment (TME). In a recent phase I trial in patients with NSCLC, in situ vaccination (ISV) with dendritic cells engineered to secrete CCL21 (CCL21-DC), a chemokine that facilitates the recruitment of T cells and DC, promoted T lymphocyte tumor infiltration and PD-L1 upregulation.Murine models of NSCLC with distinct driver mutations (KrasG12D/P53+/-/Lkb1-/- (KPL); KrasG12D/P53+/- (KP); and KrasG12D (K)) and varying tumor mutational burden were used to evaluate the efficacy of combination therapy with CCL21-DC ISV plus ICI. Comprehensive analyses of longitudinal preclinical samples by flow cytometry, single cell RNA-sequencing (scRNA-seq) and whole-exome sequencing were performed to assess mechanisms of combination therapy.ISV with CCL21-DC sensitized immune-resistant murine NSCLCs to ICI and led to the establishment of tumor-specific immune memory. Immunophenotyping revealed that CCL21-DC obliterated tumor-promoting neutrophils, promoted sustained infiltration of CD8 cytolytic and CD4 Th1 lymphocytes and enriched progenitor T cells in the TME. Addition of ICI to CCL21-DC further enhanced the expansion and effector function of T cells both locally and systemically. Longitudinal evaluation of tumor mutation profiles revealed that CCL21-DC plus ICI induced immunoediting of tumor subclones, consistent with the broadening of tumor-specific T cell responses.CCL21-DC ISV synergizes with anti-PD-1 to eradicate murine NSCLC. Our data support the clinical application of CCL21-DC ISV in combination with checkpoint inhibition for patients with NSCLC.© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.