Scientific Abstract 
Autologous bone marrow transplantation ( AuBMT ) is becoming an 
increasingly common procedure for patients with acute leukemia. The 
main cause of treatment failure in AuBMT is disease relapse but the 
source of leukemic cells responsible for relapse is unknown. 
Relapse may result from leukemic cells in the transplanted marrow, 
insufficient conditioning (i.e. leukemic cells survive the BMT 
ablative regimen) , or both. Identifying the factors leading to 
disease recurrence after AuBMT will help direct future treatment 
strategies . 
The purpose of this protocol is to determine if leukemic cells 
in the transplanted marrow are responsible, at least in part, for 
disease recurrence in relapsed patients. Patients will acute 
leukemic who are to undergo AuBMT may participate. A portion of 
their remission marrow (10%-30%) , obtained at the time of harvest, 
will be exposed to the LNL6 retroviral vector. The LNL6 vector is 
packaged in the PA317 packaging cell line and will be supplied from 
the same source as the LNL6 vector used in the TIL-N2 human gene 
transfer protocol. Marked and untreated marrow will be stored until 
the time of transplant, then infused using standard transplantation 
procedures. Patients will be periodically monitored for evidence of 
the LNL6 vector in peripheral blood and bone marrow cells. If 
patients relapse, leukemic cells will be studied to determine if 
they contain the LNL6 vector. Further studies will be performed in 
an attempt to determine the percentage of leukemic cells with the 
LNL6 vector and the clonality of the marked cells. 
In addition to evaluating the transfer of LNL6 to bone marrow 
and leukemic cells, patients will also be studied for evidence of 
treatment toxicity, such as inadvertent exposure to replication- 
competent murine retrovirus. 
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Recombinant DNA Research, Volume 15 
