Human Gene Therapy Subcommittee - July 29-30, 1991 
30 animals receiving 50 different treatments, there were no deaths using the vector 
DNA and liposomes, and no differences in serum enzyme levels were observed. 
Dr. Parkman asked in what tissues the vector DNA was detected and whether vector 
DNA was present in either ova or sperm. Dr. Nabel replied that PCR analysis of the 
organs of mice two weeks post direct intravenous injections of the liposome/DNA 
mixture showed the highest consistent level of expression in the heart and lungs. The 
pathology of these organs was normal. Dr. Parkman said two weeks may be too soon; 
a month would be preferable. Dr. Nabel said that the analysis was performed in larger 
animals at two to three months with the same results. In the larger animals, there has 
not been any vector DNA, detected by PCR analysis, in germ line tissues. Dr. Nabel 
stated that the protocol inclusion criteria will exclude patients who can reproduce; he 
proposes to request, at the time of autopsy, gonadal tissues for PCR analysis to address 
this issue. 
Dr. Nabel said the treatment enhances immunologic recognition of tumors by the 
introduction of histocompatibility antigens. However, another mechanism that may 
contribute to the effects is the induction of growth inhibitory factors within the tumor. 
The immune system and the inflammatory system are recruited. Possibly, there is an 
alteration in the process of antigen presentation. The protocol may eventually offer 
patients indirect effects in the complementation of current approaches to 
immunotherapy including TIL, adoptive transfer, and tumor vaccines. This approach 
could even be used as an adjuvant to conventional therapy. Dr. Nabel hoped that 
these studies would also provide knowledge that could be applicable to other diseases 
and to other malignancies. * 
Mr. Capron noted that the protocol is designed in such a way that there is a group of 
patients who could give consent. However, they are excluded because of their 
reproductive age. He asked if this condition was imposed upon the investigators or if 
they thought it was a necessary part of the scientific design. Dr. Nabel said he is 
willing to carry out the protocol in whatever way the committee thinks is appropriate. 
Dr. Nabel stated that until the issue of the DNA presence in nontumor tissues is 
resolved, this is the most responsible way to proceed with the protocol. 
Dr. Leventhal said that one issue is whether the gene will infect the germ line and be 
transmitted to offspring. Also, there are serious concerns about immunologic 
enhancement of tumor growth. The treatment could make these tumors grow faster 
with this type of immunologic manipulation. 
Dr. D. Miller said that if the vector has Polyoma T antigen sequences derived from a 
transforming gene, it should not be administered to patients. In rodent cells (but not 
human cells). Polyoma sequences cause an episomal replication of the transferred 
DNA. In mouse cells, constructs with the Polyoma T antigen and the Polyoma origin of 
replication multiply in an uncontrolled fashion resulting in multiple copies. In mouse 
Recombinant DNA Research, Volume 14 
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