Human Gene Therapy Subcommittee - 11/21-22/91 
approximately 1,000 of the integration sites, indicating that the chances of detecting 
relapsed cells in transplanted marrow would be greatly reduced. He asked Dr. Cometta 
to address the probability of detecting relapse. 
Dr. Gellert asked how a transduced leukemic cell can be distinguished from a transduced 
normal cell. What is the probability that stem cells would be marked that are capable of 
producing long-lived progeny, confounding the results observed from leukemia cell 
marking? 
Dr. Gellert was also concerned about the financial responsibility of patients participating 
in this protocol. The investigators have not adequately addressed the HGTS's concerns 
regarding this section of the informed consent document. In addition, the language used 
in the document is too technical for patients to understand; and in general, the document 
is not clearly written. 
Review-Dr. Erickson 
Dr. Erickson stated that he had several concerns regarding the protocol. Data have been 
supplied from only 2 cell lines; therefore, the transduction efficiency data necessary to 
defend this protocol are still inadequate at this time. In addition, freezing experiments 
have been performed using tissue culture cells, not primary cells. Data indicate a 
significant reduction in transduction efficiency using cryopreserved cells. He noted 
concerns similar to Dr. Gellert's regarding the informed consent document. 
Review-Dr. Zallen 
Dr. Zallen noted that if the proposed protocol is successful, it will allow investigators to 
design improved methods of bone marrow purging. However, the investigators do not 
propose to use purging procedures as a part of this protocol. If purging procedures are 
beneficial to these patients, why is purging not being performed? She asked Dr. 
Cornetta to respond to this portion of the experimental design. 
Dr. Zallen added that the patient population eligible for treatment is appropriate. The 
investigators have not clarified the compensation clause in the informed consent 
document regarding research related injuries. Patients will be required to pay all 
research-related injury costs. This payment is an unacceptable provision. Patients are 
also responsible for covering the costs associated with the bone marrow transplantation. 
This procedure may put them at risk of losing their health insurance coverage because 
they are participating in an experimental protocol. The question of payment and 
insurance coverage needs to be addressed at the outset of the informed consent process. 
Other Comments 
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Recombinant DNA Research, Volume 15 
