19.0 SUMMARY STATEMENT; PART 2 
GENE MARKING AND MARROW PURGING 
You are (your child is) in remission from acute myeloid leukemia (AML). But there is 
about a 65% chance that the leukemia will return. Once AML comes back it is very hard 
to treat. We believe that the best way to prevent this is to give you (your child) very high 
doses of chemotherapy to kill any leukemia cells that may be left. Then, a bone marrow 
transplant will be done using your (your child's) own bone marrow. This is necessary 
because the chemotherapy also kills normal cells in the marrow. 
Although you have agreed to this treatment, the leukemia may still come back, in some 
cases because the bone marrow we put back contains hidden leukemia cells. We would like 
you (your child) to be in a research study to find out if drug treatment of the marrow 
("purging") before we put it back can remove these leukemia cells. To do this, we will split 
the marrow into three parts and put a different genetic marker into two of them. One 
marked part will then be treated with the drug 4HC, the second with the drug Interleukin-2, 
and the last part will be frozen without treatment. Both parts of the marrow will then be 
returned to you (your child). Each step of the treatment plan is given below. 
MARROW HARVEST AND MARKING 
Before the high-dose chemotherapy starts, we will remove a small part of your (your 
child's) bone marrow from the hip bone. This will be done in the operating room under 
general anesthesia. You (your child) will not feel anything when the marrow is taken. 
There may be some pain later. You (your child) will be given medicine for the pain. 
If you agree (your child agrees) to be in the "purging" study, we will freeze about one-third 
of the marrow immediately with no treatment. If necessary, this will be used as a back-up. 
Half the remaining marrow will be marked with LNL6 and half with GIN. These are the 
names of special mouse viruses that have been changed to keep them from causing 
infection. The marker, a bacterial gene called "neoR", is put inside these special viruses. 
One half of the marrow will then be treated with a drug called 4-HC and the other with a 
drug called Interleukin-2. We think, but we do not know, that both of these treatments will 
help remove leukemic cells from your marrow. The markers let us follow the treated 
marrow in your (your childs) body to see if these drugs really do remove leukemia cells from 
the marrow, and to see which of them works best. 
RISKS 
Purging . , . . 
The major risk of "purging" is that the normal cells in marrow are also damaged by the 
drugs so that the marrow is very slow to recover. This increases the risk of infection and 
bleeding. Sometimes the marrow does not recover at all. In that case we will give back the 
portion of your/your child's marrow that was frozen without treatment. 
No bad effects have been seen in animal studies using these markers or in any person 
treated with marker genes here or at other institutions. Still, there may be risks. It is 
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