We developed a therapeutic, gene-modified, allogeneic melanoma vaccine (AGI-101H), which, upon genetic modification, acquired melanoma stem cell-like phenotype. Since its initial clinical trial in 1997, the vaccine has resulted in the long-term survival of a substantial fraction of immunized patients (up to 20 years). Here, we investigated the potential molecular mechanisms underlying the long-lasting effect of AGI-101H using transcriptome profiling of patients' peripheral T lymphocytes. Magnetically-separated T lymphocytes from AGI-101H-immunized long-term survivors, untreated melanoma patients, and healthy controls were subjected to transcriptome profiling using the microarray analyses. Data were analyzed with a multitude of bioinformatics tools (WebGestalt, DAVID, GSEA) and the results were validated with RT-qPCR. We found substantial differences in the transcriptomes of healthy controls and melanoma patients (both untreated and AGI-101H-vaccinated). AGI-101H immunization induced similar profiles of peripheral T cells as tumor residing in untreated patients. This suggests that whole stem cells immunization mobilizes analogous peripheral T cells to the natural adaptive anti-melanoma response. Moreover, AGI-101H treatment activated the TNF-α and TGF-β signaling pathways and dampened IL2-STAT5 signaling in T cells, which finally resulted in the significant up-regulation of a BCL6 transcriptional repressor, a known amplifier of the proliferative capacity of central memory T cells and mediator of a progenitor fate in antigen-specific T cells. In the present study, high levels of BCL6 transcripts negatively correlated with the expression of several exhaustion markers (CTLA4, KLRG1, PTGER2, IKZF2, TIGIT). Therefore, Bcl6 seems to promote a progenitor fate for cancer-experienced T cells from AGI-101H-vaccinated patients by repressing the exhaustion markers.

中文翻译：

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具有癌症干细胞表型的黑色素瘤治疗性疫苗可通过上调BCL6抑制疲劳并维持抗原特异性T细胞干性。

我们开发了一种基因修饰的治疗性异基因黑素瘤疫苗（AGI-101H），经基因修饰后获得了黑素瘤干细胞样表型。自从1997年首次临床试验以来，该疫苗已使相当一部分被免疫的患者长期存活（长达20年）。在这里，我们研究了使用患者外周血T淋巴细胞的转录组分析对AGI-101H产生持久作用的潜在分子机制。使用微阵列分析对来自AGI-101H免疫的长期幸存者，未经治疗的黑色素瘤患者和健康对照的磁分离T淋巴细胞进行转录组分析。使用多种生物信息学工具（WebGestalt，DAVID，GSEA）分析了数据，并使用RT-qPCR验证了结果。我们发现健康对照和黑色素瘤患者（未经治疗和接受AGI-101H疫苗接种）的转录组存在实质性差异。AGI-101H免疫诱导的外周血T细胞谱与未治疗患者的肿瘤相似。这表明全干细胞的免疫动员了类似的外周T细胞对自然适应性抗黑素瘤的反应。此外，AGI-101H处理激活了T细胞中的TNF-α和TGF-β信号传导途径，并抑制了IL2-STAT5信号传导，最终导致BCL6转录阻遏物（一种已知的增殖能力）的显着上调。中枢记忆T细胞和抗原特异性T细胞中祖细胞的介质。在目前的研究中，高水平的BCL6转录物与几种精疲力竭标志物（CTLA4，KLRG1，PTGER2，IKZF2，TIGIT）的表达负相关。因此，Bcl6似乎可以通过抑制精疲力竭标志物来促进AGI-101H疫苗接种患者的癌症T细胞祖细胞命运。