7 
Dr. Anderson said human gene therapy is a novel treatment process; in any new 
endeavor it is difficult to define what will be required since it is difficult 
to determine what is important without experience. Dr. Walters suggested a 
consensus may develop spontaneously in the field as experience accumulates. 
Changes will be made in the document when experiences suggests modifications 
are appropriate. 
Dr. Anderson said the thinking regarding the appropriate initial patient and 
the appropriate approach has recently been changing. Seme clinicians new feel 
a subject who can be helped by other options should be chosen rather than a 
patient for whan gene therapy is the last hope. At this time, an infant who 
has two years or more to live and for whem a backup therapy exists is the 
preferred candidate, in his view. For the first subjects, gene therapy should 
be the most premising of the available therapies; this situation would show 
whether or not the patient has been helped by the therapy. 
Dr. Anderson added that when his team actually came to the point of "walking 
through" a gene therapy protocol with primates, they encountered technical and 
logistical problems which were impossible to anticipate frem experience with 
mice, lb date, most researchers have performed gene transplants with mice; 
mice do not present the same types of logistical problems large animals present. 
Dr. Andersen said although his group has a great deal of experience with bone 
marrow transplants in mice, everything that technically could go wrong went 
wrong when they performed the procedure on monkeys. The procedure did not 
work in the first four monkeys; as experience has accumulated, however, 
the probability of success has increased. Experience with a large animal such 
a dog, pig, or primate is very important. 
Dr. Anderson said the "gene team" approach to gene therapy appears to be the 
optimal approach because of the logistical problems associated with the therapy; 
scientists who prepare retroviral vectors will work with experts who have 
experience in handling large amounts of bone marrew and clinicians experienced 
in bone marrew transplantation . His team at the NIH will perform gene therapy 
on four monkeys a month every month to maintain the necessary degree of famili- 
arity with the procedure. Gene therapy teams need experience with large animals. 
Ms. Witherby asked whether the working group document should mention this 
obvious fact. EP. Anderson did not think the document needed to mention this 
fact. 
Dr. Murray suggested the subworking group reiterate the statement that the 
document will be refined as experience is gained. 
Dr. Gottesman said Mr. Roger's final comment is that the working group should 
develop criteria in Part II (Special Issues) rather than simply ask questions. 
The subworking group agreed it is preferable at this time to simply ask investi- 
gators to think about these issues. 
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