Human Gene Therapy Subcommittee - 11/30/90 
Therefore, this experiment could not be used to draw the conclusion that no 
progenitor stem cells are infected. 
Dr. Cometta said the more convincing data could be derived from the monkey 
experiments involving animals who underwent autologous BMT. There was no data 
indicating that any progenitor stem cells were infected, but there was no evidence to 
the contrary. This protocol may aid in answering this question. 
Dr. Parkman said the only data provided about labelling was that 1% of the 
leukemic blasts were labeled. Dr. Epstein asked if this degree of labeling efficiency 
would warrant the experiment. Dr. Cometta noted that detection limits of PCR 
were orders of magnitude below 1%. Even with the background signal contributed 
by the vector, there should be no problem detecting the presence of the vector in 
cells by PCR. With this sensitivity and this level of insertion, the questions being 
posed by the protocol can be answered. 
Dr. Anderson said that in other collaborations, there is evidence that the vector will 
transduce between 10 to 20% of leukemic cells. Dr. Cometta agreed, noting that 
the data presented were from only one patient, and that this data should not to be 
considered the absolute level of marking for all subjects. Each patient's bone 
marrow would be analyzed by PCR; if no label is detected, then the experiment will 
not be performed in that patient. 
Dr. Epstein said the proposal should speak for itself, and the investigator should not 
rely on HGTS to correlate preclinical data from one protocol to the next. It is the 
responsibility of the investigator to show that he can perform this work within the 
context of his own protocol. 
Dr. Anderson replied that these protocols had been submitted to the HGTS for over 
two and a half months, yet the reviews were submitted 72 hours prior to this 
meeting. There is no question that Dr. Cometta is capable of performing such 
experiments at the University of Wisconsin since he performed them while at the 
National Institutes of Health (NIH). If this data is the only reason for holding the 
proposal back from being sent to the next RAC meeting, perhaps the HGTS could 
issue a conditional approval with the stipulation that Dr. Cometta provide adequate 
data from his own laboratory before going before the RAC. 
Dr. Epstein reminded Dr. Anderson that the burden of proof lies with the 
investigator to prove the existence of preliminary data and to provide it to the 
HGTS. The HGTS was making every effort to schedule its meetings to 
accommodate investigators seeking approval for protocols. The way the HGTS 
Recombinant DNA Research, Volume 14 
[387] 
