Recombinant DNA Advisory Committee - 06/1-2/92 
Dr. Murray asked Dr. Deisseroth to provide an update on his previously approved gene 
transfer protocols to the RAC members. Dr. Deisseroth presented data from four 
patients demonstrating that the transduction frequency is higher in CD34( + ) selected 
bone marrow cells than unfractionated cells. Data was shown indicating a 10% 
transduction frequency in peripheral blood cells following CD34( + ) selection. 
Dr. Deisseroth responded to Dr. Geiduschek's concerns regarding the possibility of 
contamination with replication competent virus. Dr. Deisseroth stated that the monkey 
lymphomas that developed as a result of viral infection, resulted from the administration 
of cells that had been transformed with a different retroviral vector that would never be 
approved for use in patients. 
Dr. Deisseroth noted that all of the patients entering his protocol are informed of the 
monkey data. This information is included in order to avoid any accusations of 
withholding information from patients. All of the vector supernatants and transduced 
cells will be assayed for the presence of helper virus by the NIH 3T3 amplification assay 
and the S( + )L(-) assay. 
Dr. Geiduschek asked what volume of supernatant will be used to assay for helper virus. 
Dr. Deisseroth responded that approximately 7xl0 6 cells will be transduced in a total 
volume of between 100 and 300 milliliters. Another advantage to CD34( + ) selection is 
that fewer numbers of cells are exposed to virus. Therefore, the probability of 
integrational mutagenic events is reduced. The viral content in this volume of 
supernatant is approximately 1x10 s . Since 1.5 milliliters of supernatant is used for one 
helper virus assay, the theoretical limit is approximately one particle in lxlO 6 . 
Other Comments 
Mr. Capron restated his concerns regarding the technical language included in the 
informed consent document. Dr. Deisseroth explained that he is responsible for 
providing patients with adequate information so that they can make informed decisions. 
The majority of patients eligible to enter this protocol have already participated in a 
number of research protocols at MD Anderson. These patients have already been 
exposed to and understand much of the terminology used in these informed consent 
documents, e.g., most of these patients have received interferon previously. All MD 
Anderson patients are provided with a video tape and written descriptive materials 
detailing the therapeutic program, the setting in which it is delivered, and possible 
complications before the informed consent setting is initiated. A clinic nurse spends 
many hours explaining the concepts of the therapies and the issues to these patients. As 
principal investigator of these protocols, he spends at least one hour with each of these 
patients. 
Recombinant DNA Research, Volume 15 
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