Human Gene Therapy Subcommittee - 4/5/91 
assessing trafficking. Dr. Lotze replied that 11^2 and 11^4 have proliferative effects on T 
cells, and that these cytokines produce a "leaky" effect at the tumor sites, allowing the 
TILs to invade the malignant tissue. Dr. Gellert asked if CD4^ and CD8^ cells are 
classified as TIL cells. Dr. Lotze indicated that this was correct. 
Dr. Gellert questioned if CD4^ cells kill tumor cells. Dr. Lotze explained that CD4^ 
cells can be killer cells; because they are class 2 restricted they are unlikely to kill the 
tumor cells studied in his protocol. CD4^ cells do produce a variety of cytokines 
including tumor necrosis factor (TNF), lymphotoxin, IL-2, and 11^4 which are thought to 
attract other cell types capable of mediating anti-tumor effects. He related that one of 
the most effective responses to TIL therapy occurred in a patient who received CD4^ 
cells in which there was little evidence of cell killing. He referred to a recent article in 
The Journal of Experimental Medicine in which the predictor of which class of mouse 
TILs has the best anti-tumor effects is not their cytolytic capability, but their ability to 
produce gamma-interferon or TNF in response to specific tumor stimulation. 
Dr. Epstein asked if the procedures required to analyze the biopsy material were already 
operational. All too often the committee has to determine whether to accept that the 
procedure will be worked out or to require that the investigator come forward with a 
precise description of how it is going to be performed. 
Dr. Lotze replied that he would employ techniques that are already used for other types 
of tissues. Dr. Erickson pointed out that Dr. Lotze had said that he could not do PCR 
in his laboratory because of PCR contamination. He asked if all the samples are blinded 
when sent to an outside lab. Dr. Lotze replied that all the samples are blinded. 
Dr. Epstein said the fraction of labeled cells ii> tumor versus the fraction of lymphocytes 
that carry the marker in blood, skin or another tissue should be determined. He asked if 
Dr. Lotze knew how to do quantitative PCR to get those answers, and whether there 
would be a way of independently establishing how many normal lymphocytes there are 
versus how many marked lymphocytes. 
Dr. Kelley said Dr. Lotze should perform an animal experiment to see if it is possible to 
detect the presence of the labeled cells in various tissues. One needs to determine what 
percentage of labeled lymphocytes are in lymph nodes versus muscle tissue or any other 
tissue, and thereby, master the technique prior to performing it in humans. The 
committee had expected to see this in the first TIL experiments and has not seen it yet. 
Dr. Lotze said he could provide the necessary data, and offered to come back with the 
requested information. 
Ms. Meyers asked if the patient's insurance is expected to pay for all the biopsies. Dr. 
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Recombinant DNA Research, Volume 14 
