leukemia cells. The finding of genetically marked CML cells 
at the time of relapse post-transplant implies that marrow 
purging may be a worthwhile procedure and should be 
evaluated further. With the use of insertion site analysis, 
it may be possible to detect whether relapse is derived from 
a single leukemia cell population (monoclonal) or multiple 
cells (polyclonal) . 
Biology of Hemopoietic Reconstitution after Intensive 
Therapy and Autologous Stem Cell Transplantation : 
Following myeloablative therapy autologous bone marrow 
plus peripheral blood stem cell (PBSC) infusions have led to 
rapid hemopoietic reconstitution in humans. The relative 
contribution of each to short or long term engraftment is 
unknown. Preliminary studies by Gianni 27 and Elias 47 
suggest that recovery with the combination is more rapid 
than with marrow transplantation alone. In one study the 
time to re-engraftment of platelets > 20,000/ul, neutrophils 
> 500/ul, and days to discharge from the hospital were 
shortened by 4, 7, and 11 days, respectively. 47 There were 
no instances of delayed platelet count return. 
In contrast, while many patients who receive PBSC 
autografts alone experience rapid hematologic recovery, a 
number endure incomplete or delayed reconstitution. 48 
Therefore, PBSC may provide a source of committed 
progenitors responsible for early, but often incomplete 
marrow regeneration, whereas bone marrow may contain 
pluripotent stem cells sufficient to achieve durable 
engraftment. In patients who receive PBSC alone late 
recovery may be unrelated to the autograft and may result 
from endogenous recovery. These hypotheses require further 
evaluation. By genetically marking PBSC and bone marrow, 
each with a unique retroviral construct, serial studies 
post-transplant may make it possible to determine their 
relative roles in hemopoietic reconstitution. 
4.0 Patient Eligibility Criteria at Study Entry and Prior to 
Transplant 
4.1 Patients must have a diagnosis of Philadelphia 
chromosome positive or bcr-abl positive chronic 
myelogenous leukemia. 
4.2 Patients must be age 65 or less. 
4.3 Patients must be ineligible for standard allogeneic 
marrow transplantation based on the following 
considerations : 
1. An inability to identify either a 6/6 or 5/6 HLA 
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Recombinant DNA Research, Volume 16 
