Maletzki Claudia, Gladbach Yvonne Saara, Hamed Mohamed, Fuellen Georg, Semmler Marie-Luise, Stenzel Jan, Linnebacher Michael
Molecular Oncology and Immunotherapy, Department of General Surgery, Rostock University Medical Center, Rostock, Germany.
Institute for Biostatistics and Informatics in Medicine and Ageing Research - IBIMA Rostock University Medical Center, Rostock, Germany.
Oncoimmunology. 2017 Dec 14;7(3):e1408748. doi: 10.1080/2162402X.2017.1408748. eCollection 2018.
Mismatch-repair deficiency (MMR-D) is closely linked to hypermutation and accordingly, high immunogenicity. MMR-D-related tumors thus constitute ideal vaccination targets for both therapeutic and prophylactic approaches. Herein, the prophylactic and therapeutic impact of a cellular vaccine on tumor growth and tumor-immune microenvironment was studied in a murine MLH1 knockout mouse model. Prophylactic application of the lysate (+/- CpG ODN 1826) delayed tumor development, accompanied by increased levels of circulating T cell numbers. Therapeutic application of the vaccine prolonged overall survival (median time: 11.5 (lysate) and 12 weeks (lysate + CpG ODN) vs. 3 weeks (control group), respectively) along with reduced tumor burden, as confirmed by PET/CT imaging and immune stimulation (increased CD3CD8 T - and NK cell numbers, reduced levels of TIM-3 cells in both treatment groups). Coding microsatellite analysis of MMR-D-related target genes revealed increased mutational load upon vaccination (total mutation frequency within 28 genes: 28.6% vaccine groups vs. 14.9% control group, respectively). Reactive immune cells recognized autologous tumor cells, but also NK cells target YAC-1 in IFNγ ELISpot and, even more importantly, in functional kill assays. Assessment of tumor microenvironment revealed infiltration of CD8 T-cells and granulocytes, but also upregulation of immune checkpoint molecules (LAG-3, PD-L1). The present study is the first reporting results on a therapeutic cellular MMR-D vaccine. Vaccination-induced prolonged survival was achieved in a clinically-relevant mouse model for MMR-D-related diseases by long-term impairment of tumor growth and this could be attributed to re-activated immune responses.
错配修复缺陷（MMR-D）与高突变率密切相关，因此具有高免疫原性。MMR-D相关肿瘤因此构成了治疗和预防方法的理想疫苗接种靶点。在此，在小鼠MLH1基因敲除小鼠模型中研究了一种细胞疫苗对肿瘤生长和肿瘤免疫微环境的预防和治疗作用。预防性应用裂解物（±CpG ODN 1826）可延迟肿瘤发展，同时循环T细胞数量增加。疫苗的治疗性应用延长了总生存期（中位时间：分别为11.5周（裂解物组）和12周（裂解物+CpG ODN组），而对照组为3周），同时肿瘤负荷降低，PET/CT成像和免疫刺激证实了这一点（两个治疗组中CD3CD8 T细胞和NK细胞数量增加，TIM-3细胞水平降低）。对MMR-D相关靶基因的编码微卫星分析显示，接种疫苗后突变负荷增加（28个基因内的总突变频率：疫苗组分别为28.6%，对照组为14.9%）。反应性免疫细胞识别自体肿瘤细胞，而且在IFNγ ELISpot中NK细胞靶向YAC-1，更重要的是，在功能杀伤试验中也是如此。对肿瘤微环境的评估显示CD8 T细胞和粒细胞浸润，同时免疫检查点分子（LAG-3、PD-L1）上调。本研究是首次报道治疗性细胞MMR-D疫苗的结果。在与MMR-D相关疾病的临床相关小鼠模型中，通过长期抑制肿瘤生长实现了接种疫苗诱导的生存期延长，这可归因于重新激活的免疫反应。
