Development of"immunostimulatory virotherapy"to treat various malignancies

尽管基于dc的癌症免疫疗法已被认为是多种恶性肿瘤的潜在治疗方法，但在许多人体试验中，其临床疗效仍然不足。特别是，恶性腹水（MA）是一种高度难治性和免疫治疗抵抗状态的晚期胃肠道和卵巢癌。首先，将来自癌症患者的单核细胞在优化的细胞因子混合物（GM-CSF/SCF）下进行漂浮培养，使这些细胞稳定增殖并向DC分化。与常规树突细胞一样，扩大后的树突细胞成熟后出现树突，并具有内吞活性。与常规dc一样，扩增dc也表达HLA-DR、粘附分子和共刺激分子，并产生炎症细胞因子。在功能上，MLR分析显示扩增的dc可以刺激同种异体t细胞的增殖，其程度与常规dc相同。接下来，使用CT26结肠癌细胞的小鼠MA模型，我们在这里确定VEGF-A与其诱饵受体（可溶性fms样tryrosine kinase receptor-1， sFLT-1）之间的不平衡是MA对基于dc的免疫治疗产生耐药性的主要原因。我们发现VEGF-A/sFLT-1的比值不仅在小鼠中升高，而且在人MA和f基因中也升高。缺失的重组仙台病毒（rSeV/dF）介导的dc分泌人sFLT-1不仅增强了dc本身的活性，而且还显著提高了荷瘤动物的存活率，这与CTL活性增强及其对腹膜肿瘤的浸润有关。

Though DC-based cancer immunotherapy has been suggested as a potential treatment for various kinds of malignancies, its clinical efficacies are still insufficient in many human trials. Especially, malignant ascites(MA) is a highly intractable and immunotherapy-resistant state of advanced gastrointestinal and ovarian cancers.First, floating cultivation of mononuclear cells from cancer patients under an optimized cytokine cocktail(GM-CSF/SCF) led these cells to stable proliferation and to DC differentiation. As are seen in conventional DCs, expanded DCs showed dendrites after maturation, and endocytotic activities. Expanded DCs also expressed HLA-DR, adhesion molecules, and co-stimulatory molecules and produced inflammatory cytokines as well as conventional DCs did. Functionally, MLR assay revealed that expanded DCs could stimulate allogenic T-cell proliferation to the same extent as conventional DCs.Next, using a murine model of MA with CT26 colon cancer cells, we here determined that the imbalance between the VEGF-A and its decoy receptor, soluble fms-like tryrosine kinase receptor-1(sFLT-1), was a major cause of MA resistance to DC-based immunotherapy. We found that the ratio of VEGF-A/sFLT-1 was increased not only in murine but also in human MA, and F-gene. deleted recombinant Sendai virus(rSeV/dF)-mediated secretion of human sFLT-1 by DCs augmented not only the activity of DCs themselves, but also dramatically improved the survival of tumor-bearing animals associated with enhanced CTL activity and its infiltration to peritoneal tumors.