PILOT STUDY OF DOSE INTENSIFIED PROCARBAZINE, CCNU, VINCRISTINE FOR BRAIN TUMORS

对新诊断为“预后不良”的脑肿瘤和复发性脑肿瘤患者，既未接受过化疗，也未接受过颅脑放射治疗，则给予4个疗程的时间压缩化疗，包括丙卡巴肼、环胞素和长春新碱(PCV)。外周血干细胞将在治疗前通过分离程序收集，并在每个化疗疗程后回馈给患者。为了提高骨髓对化疗药物的耐受性，我们建议采集一部分外周血干细胞，从中分离CD34+细胞，并将其与逆转录病毒载体pGK-MGMT中的人O6-甲基鸟嘌呤DNA甲基转移酶(MGMT)c DNA进行转导。这些细胞将在化疗疗程结束后与未处理的干细胞一起在化疗后返回给患者。在疗程2和3之后，只有未处理的干细胞将被回馈给患者。这是一种非清髓方案，在每个周期中输入大量未处理的单个核细胞可以最大限度地减少植入不良的风险。主要目标包括：1)确定与输注表达O6-甲基鸟嘌呤DNA甲基转移酶的逆转录病毒载体转导的CD34+细胞相关的毒性；2)确定在重组纤维连接蛋白片段CH-296存在下对细胞进行基因改造的安全性，该片段被用来帮助逆转录病毒进入哺乳动物细胞；3)确定在逆转录病毒转导过程中暴露于CH-296的细胞植入的任何证据；4)确定在体外逆转录病毒转导过程中输注暴露于CH-296的细胞后产生抗FN抗体的证据。

Patients with newly diagnosed "poor prognosis" brain tumors and patients with recurrent brain tumors who have received no prior chemotherapy and no craniospinal radiation therapy will treated with 4 courses of time compressed chemotherapy composed of Procarbazine, CCNU and Vincristine (PCV). Peripheral blood stem cells will be collected by an apheresis procedure prior to treatment and given back to the patient following each course of chemotherapy. To increase the tolerablility of the marrow to the chemotherapy drugs, we propose to collect a portion of the peripheral blood stem cells from which the CD34+ cells will be separated and transduced with the human O6-methylguanine DNA methyltransferase (MGMT) c DNA in the retrovirus construct, PGK-MGMT. These cells, will be given back to the patient following chemotherapy courses, along with unmanipulated stem cells, after course #4. Only unmanipulated stem cells will be given back to the patient following courses #2 and #3. This is a non-myeloablative protocol and the infusion of large number of unmanipulated mononuclear cells during each cycle minimizes the risk of poor engraftment. The primary objectives include the following 1) to determine toxicity associated with infusion of CD34+ derived cells transduced with a retroviral vector expressing O6-methylguanine DNA methyltransferase; 2) to determine the safety of genetic modification of cells carried out in the presence of recombinant fibronectin fragment, CH-296, utilized to assist in retroviral entry into mammalian cells; 3) to determine any evidence of engraftment of cells exposed to CH-296 during retroviral transduction; 4) to determine evidence of antibodies to FN following infusion of cells exposed to CH-296 during ex vivo retroviral transduction.