10.0 
STATISTICAL CONSIDERATIONS 
10.1 Evaluation of Origin of Relapse and Comparison of 
the Contribution of Peripheral Blood cells and 
Marrow to Recovery: We plan to initially study 
ten patients. The accrual rate is 180 new 
patients per year. Since relapsed patients are 
utilized, we estimate that 80% of patients may 
eventually relapse in two years. Thus, eight 
patients will be available for analysis of 
retroviral marking. Since 200 to 20,000 
retrovirally marked CLL cells may be infused with 
each marrow and peripheral blood collection, it 
is probable that several of the eight patients 
will produce marked cells at relapse if the cells 
infused are the origin of the relapse. The LNL-6 
and GINa marking vectors have been approved for 
use in man (See Appendix G) . 
We have calculated that if CD34 selection is 
used, 60xl0 6 cells are collected. If 30% are 
exposed to a virus. If the marking or 
transducing frequency is 10% with LNL-6 or GIN in 
CLL marrow, or GINa in peripheral blood and the 
maximum ratio of marked CLL cells to the total 
number of cells is one marked CLL cell per 
300,000 nucleated cells. The maximum number of 
marked leukemia cells to the total number of 
cells frozen. This ratio is clearly consistent 
with detection of NEO by PCR at the time of 
storage by PCR, and clearly will be adequate at 
the time of relapse since the growth of the 
leukemia cells, if relapse arises from the 
marrow, will be greater and therefore easily 
detected by PCR. 
At the time of relapse, the ratio of marked 
leukemia blasts/total unmarked cells will be 
higher. The presence of a total of 20,000 marked 
CLL cells in the autologous cells infused after 
TBI and cytoxan is clearly sufficient to generate 
a polyclonal relapse if relapse occurs from the 
infused cells. These considerations suggest that 
a pilot trial be conducted with at least 10 
patients to test if relapse occurs from infused 
autologous cells or from the residual disease 
present systemically . 
10.2 The difference in the percentage of cells 
positive for each of the two safety modified 
viruses used for the peripheral blood or marrow 
cells in the marrow after transplant and at 6 
monthly intervals following transplant will be 
used to measure the relative contribution of' the 
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