Recombinant DNA Advisory Committee- 9/12-13/94 
Dr. Zallen commented on two major areas, the experimental design of the study and the 
informed consent process. For the experimental design, she questioned if the Part C, 
which uses the same subjects who are in Part A but at a scaled up dose, is needed in this 
study. The investigator responded that it is necessary to use rare patient resources to 
obtain most scientific information. The upgraded exposure is to see if increasing vector 
dose will overcome immunity in these previously exposed subjects. Dr. Zallen asked Dr. 
Crystal to explain why increasing the vector dose could overcome immunity. She was 
concerned about the number of bronchial biopsies to be performed on these patients who 
already have damaged lungs. One biopsy will be performed after each vector 
administration. Dr. Zallen calculated that patients in Part A would have 1 biopsy; in Part 
C, a total of 4 biopsies; and in Part B, as many as 6 biopsies. Dr. Zallen asked the 
investigator to comment on the safety aspect of bronchial biopsy in CF patients. As to the 
consent process, the Informed Consent document is very long and elaborate. She said it is 
well written and covers most points. The risk/benefit ratio is reasonable. Dr. Zallen had 
an initial concern about the acceptability of this lengthy document by the patients. She 
was satisfied with the response from the investigator that he has successfully used a 
strategy for addressing this problem in a step-wise fashion. Most of the changes suggested 
for the Informed Consent document were made in the revision except the item on 
compensation for research-related injuries. Dr. Zallen said the statement is not clear 
enough to inform the patients that no such compensation is available. The wording 
should be for "medical treatment" not for "compensation" that will not be provided by the 
institution. The individuals who do sign up need to know that if there are injuries that 
medical costs will be their responsibility. 
Review-Dr. H. Ginsberg 
Dr. H. Ginsberg commented on the safety issue of using the replication deficient 
recombinant adenovirus. The comment will apply to most of the protocols using 
adenovirus vectors. The adenoviruses deleted in the El region are not truly replication 
deficient, they are only crippled. The published literature shows that if a high multiplicity 
of infections (MOI) (over 80) are used to infect cells, the viruses will replicate in cell 
culture as do the wild-type viruses. When one is using a high vector dosage such as 10 9 
pfu, as is necessary for this type of gene therapy, it raises a very important point. It is 
very difficult to determine the MOI in the human situation since the number of target 
cells is unknown. Some cells may get an MOI of over 250, 500, or even 1,000. Dr. H. 
Ginsberg referred to toxicity associated with glycerol. The Ad.CFTR vectors are 
frequently stored in 10% glycerol. Such concentration of glycerol will kill a cotton rat. It 
has to be diluted to 1 to 2% to avoid the induced inflammation. Dr. H. Ginsberg noted 
that adenovirus vectors with an additional E3 deletion, such as the one proposed in this 
study, are markedly more pathogenic than the wild-type virus. E3 deletion increases the 
problem of inflammatory response. Dr. H. Ginsberg said that examining the vector- 
induced cytokines in serum is inadequate. In the cotton rat experiments, tumor necrosis 
factor (TNF)-a, interleukin (IL)-l, and IL-6 appear in the lung very early after infection, 
and only IL-6 has been detected in the serum. TNF-a is very critical in causing the 
inflammatory reaction. Regarding the animal experiments used to assess toxicity, the 
animal’s lungs were examined 30 days after infection. Dr. H. Ginsberg said most early 
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