B7 1 GENE MODIFIED TUMOR CELL VACCINE FOR RENAL CELL CA

近年来，人们对开发针对恶性肿瘤的免疫学方法越来越感兴趣，并且有很好的证据表明，肾细胞癌（RCC）的生长可以由宿主的免疫系统调节。 事实上，免疫调节细胞因子白细胞介素-2（IL-2）的使用已被批准用于这种疾病的治疗。 这种方法的疗效仍然很低，并且对于转移性RCC患者没有其他合理的常规治疗方法。 因此，需要开发新的治疗策略。 开发自体肿瘤细胞疫苗是一种方法，经过遗传修饰使其更具免疫原性。 其中一种基因操作正在被几个研究小组研究，它是通过表达B7-1来为肿瘤反应性T细胞提供共刺激。 其基本原理是，为了产生细胞毒性反应，T细胞需要两种信号：T细胞受体（TCR）与MHC上呈递的抗原肽的结合，以及CD 28与B7-1的结合。 由于B7-1通常不被RCC细胞表达，通过转染外源性B7-1基因强制表达可使肿瘤细胞更具免疫原性。我们最近完成了一项I期临床试验，患者正在接受自体肿瘤细胞的治疗，这些细胞被修饰为表达B7-1，作为肿瘤疫苗。 原发性肿瘤或转移瘤从IV期RCC患者中切除。 使肿瘤细胞适应体外培养;用含有由CMV启动子驱动的人B7-1 cDNA的重组腺病毒载体感染;辐射;并储存在液氮中。 根据剂量递增方案，将B7-1基因修饰的肿瘤细胞的等分试样作为疫苗以不同的间隔给予患者。 患者还接受全身性IL-2，用于为这种疾病提供可接受的治疗以及扩增由疫苗激活的肿瘤反应性T细胞的双重目的。 正在对12名患者进行疫苗的免疫原性和毒性评估。 第一阶段试验将在四个月内（2000年1月）完成所有数据的收集和分析。一旦完成，我们建议使用相同的方法进行一项涉及30名患者的II期试验。 主要目的是确定肿瘤缓解率。 将通过对患者外周血淋巴细胞进行的ELISPOT测定和在皮内注射自体未修饰肿瘤细胞后48小时进行的DTH皮肤试验活检的免疫组织化学分析来评估治疗的免疫原性。

There has been increasing interest in recent years in developing immunologic approaches to malignancies, and there is good evidence that the growth of renal cell carcinoma (RCC) can be modulated by the host's immune system. In fact the use of the immunomodulatory cytokine interleukin-2 (IL-2) is approved treatment for this disease. The efficacy of this approach remains low, and there is no other reasonable conventional therapy for patients with metastatic RCC. Therefore there is a need to develop novel treatment strategies. The development of autologous tumor cell vaccines, genetically modified to render them more immunogenic is one approach. One such genetic manipulation that is being studied by several groups is to everexpress B7-1 to provide costimulation to tumor-reactive T cells. The rationale for this is that in order to mount a cytotoxic response, T cells need two signals: the binding of the T cell receptor (TCR) to an antigenic peptide presented on MHC, and the binding of CD28 to B7-1. Since B7-1 is not normally expressed by RCC cells, the forced expression by transfection of an exogenous B7-1 gene could make the tumor cells more immunogenic. We recently completed accrual to a Phase I clinical trial where patients are being treated with autologous tumor cells modified to express B7-1 which functions as a tumor vaccine. Primary tumors or metastases were resected from patients with stage IV RCC. The tumor cells were adapted to in vitro culture; infected with a recombinant adenoviral vector containing the human B7-1 cDNA driven by the CMV promoter; radiated; and stored in liquid nitrogen. Aliquots of the B7-1 gene-modified tumor cells are being administered to the patients as a vaccine at varying intervals according to a dose escalation scheme. The patients also receive systemic IL-2 for the dual purpose of providing accepted therapy for this disease as well as expanding the tumor- reactive T cells activated by the vaccine. The immunogenicity and toxicity of the vaccine are in the process of being assessed in 12 patients. The Phase I trial will be completed with all of the data collected and analyzed in four months (January 2000). Once completed, we propose to conduct a Phase II trial involving 30 patients using this same approach. The primary objectives will be to determine tumor response rates. The immunogenicity of the treatment will be assessed by ELISPOT assays performed on the patients' peripheral blood lymphocytes and by immunohistochemical analysis of DTH skin test biopsies performed 48 hours after the intradermal injection of autologous, unmodified tumor cells.