在有晚期结肠腺瘤病史的个体中进行了一项单臂试验 (NCT007773097) 和一项双盲、安慰剂对照随机试验 (NCT02134925)，以测试 MUC1 肿瘤抗原疫苗的安全性和免疫原性及其预防新发腺瘤的潜力。这是在没有癌症的情况下施用非病毒癌症疫苗的前两项试验。该疫苗对 43% (NCT007773097) 和 25% (NCT02134925) 的参与者来说是安全且具有强免疫原性的。大量参与者缺乏反应，这首次表明，即使在癌前环境中，免疫系统也可能已经受到先前仅在癌症中报道的某种程度的抑制。对来自 16 名免疫应答者和 16 名无应答者的疫苗接种前外周血单核细胞 (PBMC) 进行单细胞 RNA 测序 (scRNA-seq)，确定了有效疫苗应答的特定细胞类型、基因和途径。应答者在接种疫苗前的 CD4 初始 T 细胞百分比显着较高，但 CD8 T 效应记忆 (TEM) 细胞和 CD16 单核细胞百分比显着较低。差异基因表达 (DGE) 和转录因子推断分析显示 CD4 初始 T 细胞中 T 细胞激活基因（例如 Fos 和 Jun）的表达水平较高，通路分析显示应答者中信号传导活性丰富。此外，贝叶斯网络分析表明这些基因在机制上与反应相关。我们的分析确定了几种免疫机制和候选生物标志物，有待进一步验证，作为预防性癌症疫苗免疫反应的预测因子，这可以促进选择可能受益于疫苗或用于改善疫苗反应的个体。

A single arm trial (NCT007773097) and a double-blind, placebo controlled randomized trial ( NCT02134925 ) were conducted in individuals with a history of advanced colonic adenoma to test the safety and immunogenicity of the MUC1 tumor antigen vaccine and its potential to prevent new adenomas. These were the first two trials of a non-viral cancer vaccine administered in the absence of cancer. The vaccine was safe and strongly immunogenic in 43% (NCT007773097) and 25% ( NCT02134925 ) of participants. The lack of response in a significant number of participants suggested, for the first time, that even in a premalignant setting, the immune system may have already been exposed to some level of suppression previously reported only in cancer. Single-cell RNA-sequencing (scRNA-seq) on banked pre-vaccination peripheral blood mononuclear cells (PBMCs) from 16 immune responders and 16 non-responders identified specific cell types, genes, and pathways of a productive vaccine response. Responders had a significantly higher percentage of CD4+ naive T cells pre-vaccination, but a significantly lower percentage of CD8+ T effector memory (TEM) cells and CD16+ monocytes. Differential gene expression (DGE) and transcription factor inference analysis showed a higher level of expression of T cell activation genes, such as Fos and Jun, in CD4+ naive T cells, and pathway analysis showed enriched signaling activity in responders. Furthermore, Bayesian network analysis suggested that these genes were mechanistically connected to response. Our analyses identified several immune mechanisms and candidate biomarkers to be further validated as predictors of immune responses to a preventative cancer vaccine that could facilitate selection of individuals likely to benefit from a vaccine or be used to improve vaccine responses.