cancer patient benefits directly from chemotherapy. He said he 
felt the risk-benefit ratio is important to the patient and must 
be considered. 
Dr. Rosenberg noted that Phase I studies of chemotherapeutic 
agents are routinely performed without potential for patient 
benefit, and the potential benefit to patients from this kind of 
protocol probably exceeds that of most Phase I studies in 
progress in cancer research. 
Dr. Musgrave asked Dr. Kelley if any public health risks were 
found, other than the ones mentioned previously with regard to 
health workers, and whether there was any incremental risk of 
mortality to the patients. Dr. Kelley said these were the 
questions being asked, but he did not think the investigators 
knew the risks. Further, Dr. Musgrave asked if cutting the life 
expectancy of a patient by 30 days was significant in this group 
of terminal patients. Dr. Kelley answered that he was not an 
expert in the area of ethics, but others in the room were better 
able to answer such a question. Dr. Anderson said there were 
three years of data in primates showing that this vector has not 
been responsible for any pathology. 
Dr. Cohen said he thought the experiment was logical; because, 
contrary to inserting something toxic, it was merely inserting a 
marker, that will aid in answering many questions on the 
consequences of human gene therapy. With respect to the 
individual host receiving the therapy, he said the development of 
further illness down the road was not important. The patients 
will have a very short life expectancy. However, the issue of 
future retroviral infections is a valid public health concern. 
Therefore, he asked whether people can be infected with this 
particular helper virus. 
Dr. Anderson said the vector is a Moloney murine retrovirus which 
can infect the host, however, it is packaged in a murine 
amphotropic envelope. Many human cells are infected and can 
maintain a replication cycle. However, there is a question as to 
the danger that might result from putting a small amount of virus 
into a human. In order to examine this possibility, a monkey was 
infected with a small amount of viral supernatant which was 
intentionally contaminated with replication competent virus as 
well as 4070A wild type murine amphotropic virus--a total of 10 7 
viral particles--and nothing happened. After 17 months, the 
animal has shown no indication of a problem. A second monkey was 
given a larger bolus injection in the same manner and a third had 
22 percent of its blood volume replaced with pure viral 
supernatant. This animal exhibited transient lymphadenopathy 
from day 7 to day 14 with no ability to grow virus from the lymph 
nodes and no indication that anything other than viral antigens 
were present. 
Recombinant DNA Research, Volume 13 
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