Lymphoma, gene therapy trials

Cumulative experience from 106 monkey-years and 23 human-years of retroviral gene therapy had revealed no side-effects or malignancies. Recently, however, three monkeys used in clinical trials developed T cell lymphomas which were traced to a helper virus-contaminated retroviral vector preparation (Anderson, 1992a). Contamination of defective viral vector stocks by infectious viruses produced in helper cells was a serious problem with the early version of the helper cells. New helper cell lines which greatly reduce the probability of virus production have been developed (Miller, 1990). Eurther, it is also imperative to test the lots of vector virus preparations used in therapy for the presence of other infectious viruses. The probability... 

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