Recombinant DNA Advisory Committee - 2/10-11/92 
Presentation— Dr. Cornetta 
Dr. Cornetta explained the difference between his protocol and other similar protocols. In 
this study, the patients are in second or later remission, a high-risk group. Seventy to 80% 
of the patients will probably relapse from the disease. The sources of relapse could be 
insufficient therapy that did not kill leukemia cells present in the body, leukemic cells in 
the transplanted marrow, or combination of the two. This protocol attempts to prove that 
autologous BMT is an effective treatment for acute leukemia and to explore areas for 
treatment improvement. One possibility would be to have the marrow reinserted in the 
patients and marked with the neomycin resistance gene to confirm that the marrow- 
purging procedure has some scientific and biologic rationale. This procedure would 
provide a tool for assessing purging methods to see if they are effective in removing 
leukemic cells in the marrow. 
Dr. Cornetta said the vector insertion in the normal marrow progenitor cells will be 
examined and followed over time to determine the background rates for marking in 
normal marrow. Leukemic cells of patients who relapse will be examined to determine 
whether insertion of the vector into those leukemic cells was achieved. 
Dr. Cornetta reviewed the patient profile. Patients must be between the ages of 18 and 
65, must be able to give informed consent, must have a good performance status, must 
have no evidence of active infection, and must undergo a fairly rigorous multi-organ 
assessment prior to BMT. The patients must be in a second or later remission. 
One week prior to the marrow infusion, a patient's cells will be examined by light 
microscopy and cytogenetics, which is routine for any transplant. Negative control samples 
will be collected; and PCR analysis will be performed to detect the LNL6 vector, 
methylcellulose colony assays, replication-competent amphotropic virus assays, and 
immunoassays for murine retrovirus. Samples will also be analyzed by Western blot to 
ensure that the patient does not develop antibiotics to replication-competent amphotropic 
virus. 
If the PCR and methylcellulose assays are negative and if any of the viral studies are 
positive, the marrow will not be infused. The studies would be repeated as the patient 
reconstitutes; and if the patient relapses, these tests would be repeated. The sensitivity of 
their PCR assay is equivalent to those in the literature. Detecting false positive results in 
PCR is a problem. In the past, leukemic blasts from peripheral blood have been obtained, 
marked with LNL6, and processed in his laboratory (some were sent to another NIH 
laboratory for processing). The two laboratories obtained similar results regarding 
sensitivity and the ability to isolate the DNA without contamination. 
Recombinant DNA Research, Volume 15 
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