Recombinant DNA Advisory Committee - 03/1-2/93 
vector if the effect of a single dose is unknown. There is a possibility that patients may 
not demonstrate a clinical response at the lower concentrations; therefore, why would 
you subject a non-responsive group of patients to a second administration? Dr. Whitsett 
explained that if the objective of the protocol was to demonstrate efficacy, then there 
would be a flaw in the experimental design. However, the objective of the protocol is to 
determine toxicity and whether a second dose of vector is feasible. This study is 
designed to determine safety, not efficacy. 
Dr. Parkman said that it is difficult to approve a protocol in which a second 
administration of vector has not been tested in a large animal model. He said that he 
would more readily vote for approval of the protocol if it involved only a single 
administration of the vector. Dr. Whitsett stated that a single dose would be a fall-back 
position; however, it would be preferable to proceed with the protocol as it was originally 
proposed. Ms. Grossman said that she would prefer that only a single administration be 
approved by the RAC until such time that in vivo preclinical data was available in a 
large animal model. Dr. Whitsett requested permission to change the design of the 
protocol to include a single administration of the vector instead of 2 doses. 
Dr. Miller inquired about the effect of neutralizing antibodies on the adenovirus vector. 
Dr. Trapnell stated that in vivo data demonstrates that adenovirus infection is possible in 
the presence of overwhelming levels of serum antibody. The lymphocytic and monocytic 
immune responses that are observed are transient regardless of whether animals are 
immune. 
Dr. Trapnell responded to questions regarding the ability to detect gene expression. A 
technique was developed for evaluating gene expression in the respiratory epithelium 
using bronchoscopies to obtain brushing samples. Millions of ciliated and secretory cells 
can be obtained in this fashion. Gene expression is evaluated by quantitative PCR. 
Gene expression has been demonstrated in respiratory tract cells from the nose through 
the bronchus; however, gene expression is depressed in the pharynx. Comparison 
between quantitative PCR and the amount of hybridization will provide an estimate as to 
the copy number per cell. 
Ms. Grossman asked the investigators to describe the in situ hybridization assays that 
have been performed. Dr. Whitsett explained that the investigators have been successful 
in distinguishing both the endogenous and transferred gene by in situ hybridization. Dr. 
Whitsett stated success at detecting several copies of CFTR per cell by this method. 
In response to Dr. Zallen's concerns, Dr. Whitsett said that a revised flow chart has been 
prepared to assist the patient in understanding the various procedures and time points; 
however, the second administration phase will be deleted. Patients will be followed by 
Dr. Robert Baughman who is the Director of the adult program of the Cystic Fibrosis 
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Recombinant DNA Research, Volume 17 
