Recombinant DNA Advisory Committee - 12/3-4/92 
consent document. In response to concerns regarding third party casual contact, Dr. 
Crystal stated that the transfer probably would not occur through casual contact. 
Regarding the number of bronchoscopies, Dr. Crystal stated that he has had experience 
with CF patients who have received more than 40 bronchoscopies over a period of time. 
In order to demonstrate biological efficacy and to proceed to future protocols, the 
number of bronchoscopies outlined in the protocol are probably necessary. There will be 
a minimum of 5 and a maximum of 9 obligatory bronchoscopies. The language 
describing the bronchoscopy procedures will be clarified. Dr. Crystal stated that there is 
no evidence that lidocaine has any effect on gene transduction or expression. 
Discussion 
Dr. Post asked if the 20 ml volume of vector will be removed. Dr. Crystal acknowledged 
that the 20 ml will be removed after the appropriate period of time. Dr. Post asked if 
patients tend to cough when this volume of material is administered. Dr. Crystal said 
that the local anesthetic causes the patient to lose their cough reflex. Patients are 
observed while they retain the 20 ml volume, and they are not allowed to eat during this 
period. 
Is negative pressure isolation absolutely critical for these patients? Dr. Crystal said that 
the rational for this level of containment was to use the same criteria required for 
adenovirus laboratory work. He added that they were trying to be extremely 
conservative, and that negative pressure containment would be employed regardless of 
the RAC's decision. 
Dr. D. Miller asked for further information regarding Ela assessment. Dr. Crystal said 
that they are able to detect Ela with a level of sensitivity of less than 2 copies per 10 9 
PFU. Dr. D. Miller asked if a bioassay will also be performed? Dr. Crystal said that 
vector replication assays will be performed on freshly isolated normal human airway 
epithelium at an MOI of 1000. Dr. Crystal noted that assays are not performed with 10 10 
epithelial cells, because this experiment would be technically impossible. Dr. D. Miller 
asked why HeLa cells are not used for the replication-competent assays. Dr. Crystal 
explained that the gold standard is the in vivo cells, which is the airway epithelium. 
Dr. Geiduschek inquired if the safety margin of the vector could be improved by 
increasing its length to the packaging limit; therefore, decreasing the likelihood of 
acquiring a sequence that would increase replication-competence of other properties. 
Dr. Crystal explained that as the 100% limit is approached, the construct probably 
becomes less stable, and it is harder to obtain the same levels of titer. AdCFTR has 
been passaged over 15 months. The sequence of the construct after that length of time 
has remained unchanged. 
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