近日，匹兹堡大学癌症研究院的科学家研发出一种针对结肠癌的疫苗，能在高危人群出现结肠癌早期迹象时启动人体的免疫功能对其进行攻击。

　　由匹兹堡大学研发的这种疫苗是该领域首款被用于人体检测的疫苗。前临床模型试验显示，这种疫苗可靶向作用于肿瘤内的异常细胞，从而发挥相关的治疗作用。该疫苗可靶向作用于一种特定的细胞蛋白，这种蛋白在肿瘤发生恶化以及腺瘤(一种前癌肿瘤)出现之前发生改变并过量生成。这种蛋白会在胰腺癌、乳腺癌、肺癌和前列腺癌中出现异常。匹兹堡大学研究人员计划就这种疫苗对这些癌症的有效性进行检测。　

　　在之前的一项小型临床检测中，研究人员对39名年龄在40到70岁之间的患者进行了这种疫苗的检测，这些患者虽然没有癌症，但却有晚期腺癌病史。结果显示，疫苗对其中的17名(44%)患者起到了明显的效果。

　　疫苗研发者、匹兹堡大学医学院免疫科主任Olivera Finn表示：“这种预防结肠癌的疫苗可增强人体的自然免疫监控功能，从而或能在前癌病变发展到肿瘤之前对其进行清除。这样就能避免因重复进行侵入性监控检测(例如结肠镜检查，这种检查目前常被用于发现并移除前癌息肉)而给患者带来的相关风险和不便。”

　　临床试验中，患者一开始会接受一定剂量的疫苗注射，而在之后2周和10周的时候再分别接种一次。研究人员在接种前和接种后12周、28周以及1年的时候分别提取患者的血液样本，对患者的免疫反应进行评估。患者在1年之后需要再进行一次强化注射以保证免疫反应的持续有效性。

　　MUC1 Vaccine for Individuals with Advanced Adenoma of the Colon: A Cancer Immunoprevention Feasibility Study

　　Abstract

　　Cancer vaccines based on human tumor-associated antigens (TAA) have been tested in patients with advanced or recurrent cancer, in combination with or following standard therapy. Their immunogenicity and therapeutic efficacy has been difficult to properly evaluate in that setting characterized by multiple highly suppressive effects of the tumor and the standard therapy on the patient's immune system. In animal models of human cancer, vaccines administered in the prophylactic setting are most immunogenic and effectively prevent cancer development and progression. We report results of a clinical study that show that in patients without cancer but with a history of premalignant lesions (advanced colonic adenomas, precursors to colon cancer), a vaccine based on the TAA MUC1 was highly immunogenic in 17 of 39 (43.6%) of vaccinated individuals, eliciting high levels of anti-MUC1 immunoglobulin G (IgG) and long-lasting immune memory. Lack of response in 22 of 39 individuals was correlated with high levels of circulating myeloid-derived suppressor cells (MDSC) prevaccination. Vaccine-elicited MUC1-specific immune response and immune memory were not associated with significant toxicity. Our study shows that vaccines based on human TAAs are immunogenic and safe and capable of eliciting long-term memory that is important for cancer prevention. We also show that in the premalignant setting, immunosuppressive environment (e.g., high levels of MDSC) might already exist in some individuals, suggesting an even earlier premalignant stage or preselection of nonimmunosuppressed patients for prophylactic vaccination.