Genzyme Corporation Ad2/CFTR-2 Gene Transfer Protocol: Single 
One Kendall Square, Cambridqe, MA 02139 Aerosol Administration to the Lunq of CF Patients 
RISK ASSESSMENT 
The risks associated with somatic cell gene transfer using the Ad2/CFTR-2 gene construct in humans are unknown. 
However, we now have experience with administration of the related Ad2/CFTR-1 construct to humans. The data 
suggest that there was no viral replication nor any adverse symptoms or findings that could be attributed to the 
recombinant virus. Others have reported lung inflammation in baboons following administration of adenovirus vector 
[27], In addition, an adverse reaction to bronchoscopic administration of an adenovirus vector to the lung of one CF 
patient has been reported [28]. This reaction consisted of fever, dyspnea and a pulmonary infiltrate. The symptoms 
were reported to be not severe and have resolved without sequelae. 
Inflammation and Immune Response 
It is possible that inflammation, either bronchial or parenchymal could occur as a result of an immune response to the 
recombinant virus. Local cytopathic effects on the respiratory epithelium are also possible. Inflammation or cytopathic 
effects may manifest with cough, fever, chest pain, hemoptysis, and increased phlegm production. However, serious 
effects appear very unlikely. 
Virus Replication 
The Ad2/CFTR-2 viral construct has been rendered defective for replication by deletion of two important early genes, 
El a and El b. The majority of the E4 region has also been deleted. However, it is possible that the virus will have a 
limited ability to replicate in human cells. Furthermore, under certain circumstances, the viral defect could be 
complemented. Such circumstances include coinfection with wild-type adenovirus or provision of El gene function by 
latent or residual adenovirus resulting from an earlier infection. Finally, epithelial cells might also provide normal 
proteins with El -like functions that are able to complement the defective virus. 
Most of these possibilities seem remote. The likelihood of coinfection of treated cells with wild-type virus is minimized 
by prior screening of the patients. Moreover, in the unlikely event that coinfection with wild type adenovirus did occur, 
Ad2/CFTR-2 is missing much of the E4 region and is unlikely to compete with wild-type virus. Thus, a wild-type 
infection would probably become self-limiting. 
Environmental Risks 
There is a risk that the virus could be passed to another person. This could occur if a caregiver or visitor is exposed to 
the virus we apply to the patient or exposed to virus that has replicated in the patient. As described immediately above, 
replication of Ad2/CFTR-2 in the patient is very unlikely. To minimize the risk of exposure to persons other than the 
participant, the patient will be kept in isolation for 1 day after vector administration and in the hospital for 3 days. Were 
environmental release to occur, the most likely virus involved would be wild-type adenovirus that had overgrown 
Ad2/CFTR-2 or a recombinant with no biological activity other than that associated with wild-type virus. The closed jet 
nebulizer system will utilize a filter to outflow and will be done within a hood or other device to minimize any 
environmental risk related to aerosolization of the vector. Decontamination using standard chemical agents will be 
performed on exposed environmental surfaces following aerosolization. 
Effects of Wild-type Adenovirus 2 Infection 
Potential effects of wild-type adenovirus 2 include symptoms of upper respiratory infection. Pharyngitis and 
conjunctivitis are known to be associated with adenovirus. Strains of adenovirus other than adenovirus 2 have been 
known to cause pneumonia, transient diarrhea and gastroenteritis. Rare problems associated with adenoviral strains 
include cystitis and keratoconjunctivitis. Such problems may be hazardous in immunocompromised hosts. The 
possible role of adenovirus in oncogenesis has been under investigation with no evidence to suggest a role for 
adenovirus in human oncogenesis. 
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Recombinant DNA Research, Volume 20 
