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Purging Grafts Via CD34+ Cell Selection May Show Benefits

Purging Grafts Via CD34+ Cell Selection May Show Benefits

NASHVILLE--Results of a trial of positive-selection purging in
breast cancer patients undergoing high-dose chemotherapy/autologous
bone marrow or peripheral blood transplantation show that patients
who have no evidence of breast cancer in the graft after purging
have longer progression-free survival at a median follow-up of
18 months than patients who have persistent evidence of tumor.
Purging is performed by selection of CD34+ marrow or peripheral
blood progenitor cells (PBPCs).

Speaking at a scientific session of the annual meeting of the
American Society of Hematology (ASH), Elizabeth J. Shpall, MD,
described her study of 121 patients with advanced (47) or high-risk
(74) breast cancer undergoing transplantation, as well as ongoing
efforts at ex vivo expansion of CD34+ selected stem cells.

Patients were divided into several cohorts who received either
CD34+ marrow, blood, or both. Of the 47 stage IV patients (who
were treated on phase I protocols), 13 were found to have no evidence
of cancer in their grafts after purging, and these patients had
a significantly higher duration of disease-free survival than
the 34 patients whose grafts still contained tumor following positive
selection, said Dr. Shpall, associate professor of medicine, University
of Colorado Health Sciences Center, Denver.

In a third group of 55 patients in whom no tumor cells were ever
detected in their grafts, disease-free survival times fell in
between those of the other two groups and did not differ significantly
from either one.

In a multivariate analysis of all the patients (including the
74 high-risk patients enrolled in phase II protocols), the grafts
that contained breast cancer both before and after positive selection
(referred to as positive-to-positive) were used as the reference.

"The purification of the graft to negativity and enrollment
on phase II as opposed to phase I studies were the only two covariants
that independently predicted for a significantly better disease-free
survival," Dr. Shpall said. P values were identical for the
two variables at .005. When these two variables were combined,
P value was even more significant.

Factors found to have no significant effect on relapse-free survival
were patient age; disease-free interval between diagnosis and
transplant; transplantation with CD34+ marrow, blood, or both;
estrogen receptor status of the tumor; and administration of adjuvant
chemotherapy, Dr. Shpall said.


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