Recombinant DNA Advisory Committee - 03/1-2/93 
patients underwent autopsies at the time of death. This standard request is entered into 
the patient's chart at the time the family is contacted. 
Ms. Meyers asked if all of the deaths occurred at St. Jude. Dr. Brenner responded that 
3 of the 4 patients died while at St. Jude, and that all of the autopsies were performed at 
St. Jude. 
Dr. Brenner explained that the IL-2 purging procedures will be performed in Vancouver. 
Four bone marrow preparations have been shipped back and forth from St. Jude to 
Vancouver, and the cells have remained viable. After the cells are purged in Vancouver, 
they will be sent back to St. Jude to be grown in culture for 7 days and then 
cryopreserved. The purged cells have retained their viability upon thawing. 
Dr. Parkman inquired if any patients have received ABM transplantation with IL-2 
purged cells that have not been gene-marked. Dr. Brenner answered that no patients 
have received IL-2 purged ABM cells at St. Jude; however, 14 patients have undergone 
this procedure at another institution. Dr. Brenner stated that there is no evidence that 
the sensitivity of these cells to 4-HC is altered following the 6 hour incubation period. 
Dr. Brenner stated that all of the patients who have not relapsed are evaluable for 
engraftment. Of these 18 patients, 16 demonstrated marked cells which are 
hematopoietic progenitor cells, lymphoid cells, or a combination of both. The level of 
marking ranges between 1 and 12%, which is much greater than was originally 
anticipated. 
Dr. Brenner explained that the reason that the magnetic bead separation procedures 
have not been used for these studies is that the technique requires an antibody that 
specifically recognizes the leukemic cells. These cells do not usually possess a unique 
phenotype. The 4-HC and IL-2 purging methods were chosen because effective purging 
will probably prove to be a combination of these two techniques. To date, the most 
successful treatment of leukemia has proven to be a combination of therapies which do 
not cause excessive toxicity. 
Dr. Parkman asked Dr. Brenner whether the St. Jude IRB was concerned that the 
shipment of cells to Vancouver imposed any increased risk to the patient. Dr. Brenner 
said that two-thirds of the marrow remains cryopreserved at St. Jude; therefore, any 
unforeseen loss of the shipped cells should not affect engraftment of the untransduced 
cells. Dr. Brenner agreed; however, that the shipment issue should be included in the 
informed consent document. 
Dr. Post noted that all patients will receive both purging procedures. He inquired if 
there would be any additional benefit if the patients were divided into groups that 
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Recombinant DNA Research, Volume 17 
