Human Gene Therapy Subcommittee - 4/5/91 
marked cells could be detected. There were at least two potential approaches for 
detection that could be employed; PCR with all its inherent quantitation problems, and 
in situ hybridization assays with antibodies that could detect the neomycin gene in tissue 
sections. 
Dr. Lotze reported that Dr. Blaese was currently testing some antibodies and that great 
effort has been expended in the last months to develop such reagents. Further, his group 
at the University of Pittsburgh is trying to develop in situ techniques for the detection of 
cytokines and cytokine message which are believed to be meeting with success. They are 
beginning work on in situ hybridization for the neomycin gene as well. 
In terms of the sensitivity of detecting transduction frequency. Dr. Lotze said that Dr. 
Gellert was correct in noting that no data was supplied showing that his laboratory was 
capable of detecting 1 in 100,000 cells. Data was supplied which indicated that 1-10% 
could be detected by a crude assay employed in the lab using whole cell lysates. 
Historically, his laboratory had been using Genetic Therapy, Inc. (GTI), to perform its 
PCR studies. The investigators been able to demonstrate a 1 in 100,000 sensitivity. GTI 
had agreed to run the PCRs on the samples from this study. They had encountered 
problems associated with doing PCR on the neomycin gene in his laboratory and would 
continue working on it if the committee requested this, but the current plan was to have 
GTI perform the assays, based on its proven abilities. 
Dr. Lotze discussed the issue of how it can be determined whether the combination IL- 
2/IL-4 treatment will be superior to treatment with IL-2 alone. In prior immunotherapy 
experiments, the response rates with the combination therapy showed mixed results in 
comparison to treatment with IL-2 alone, but the sample size was small. He described 
two possibilities for the next set of studies, broad randomized studies directly comparing 
IL-2 with IL-2/IL-4 combinations or using the available animal models, as well as his 
own intuition, to try to make major improvements. Dr. Lotze said that his intuition, 
based on the ability to grow melanoma TILs in IL-2 and IL-4, and their successful 
administration to patients, was that the provision of these factors will be beneficial. He 
said he would rather continue pushing ahead than do the broad randomized studies. 
Dr. Lotze said the central question was whether trafficking of cells to tumor sites was 
improved with the combination treatment. If his results showed better trafficking than 
what was obtained previously in Dr. Rosenberg's laboratory, then the only way to really 
address the issue would be a broad randomized study requiring larger sample sizes. 
Dr. Lotze noted that the original consent document supplied with the protocol was 
modeled after a consent document that had been exhaustively reviewed by individuals at 
the National Institutes of Health. It was revised after its additional review by six 
different committees. If the subcommittee felt there were items in the document which 
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Recombinant DNA Research, Volume 14 
