Autologous Bone Marrow Transplantation - Blog Science Connections

ABMT in Burkitt's Lymphoma 259
initial CNS and abdominal Burkitt's lymphoma involvement, more than 80%
marrow involvement, but a normal WBC count. Both reached a quick CR
under the induction protocol. Each was given 20 Gy to the CNS before ABMT,
and both received BACT (Institut Gustave-Roussy) or BEAM when in welldefined
CR and received histologically normal marrow purged by monoclonal
antibodies and complement. Central nervous system relapses occurred very
early (day 30 and day 37) after a quick recovery following massive therapy
that did not produce major complications. In one case the marrow was clearly
normal at the time of relapse, and immunodepression because of massive
therapy in the explosive relapse is questionable. In the other case the relapse
occurred at the same time in the marrow as it did in the CSF, and it is possible
that Burkitt's lymphoma cells contaminated them because in vitro data
showed that in this case the addition of RFB 7
or would have been
necessary to effectively purge the marrow (see the above-named chapter by
Favrot et al. and the chapter by I. Philip et al, "Using a Liquid Cell Culture
Assay to Measure In Vitro Elimination of Burkitt's Cells From Bone Marrow,"
both in this volume). Unfortunately, we were not able to use these antibodies
for ex vivo treatment at that time.
We have previously shown in vitro that Burkitt's lymphoma cells could
grow in a liquid culture system from cytologically and histologically normal
marrow (35,38,41). On the basis of this test we showed that marrow
apparently normal at the time of harvest grew lymphoma cells in culture
(35,38,41; see also the above-named chapter by 1. Philip et al. in this volume).
However, whether cells that grow in liquid culture are capable of reestablishing
a malignancy when reintroduced into the human is unknown. We,
nevertheless, selected a cocktail of three monoclonal antibodies that would
react with virtually all Burkitt's lymphoma and developed a purging procedure
using complement lysis (32,42; see also the above-named chapter by Favrot
et al. in this volume). We believe, however, that ultimately a number of
different techniques will have to be associated for in vitro purging to be
successful (43; see also V. Combaret et al, "Eliminating Burkitt's Cells From
Excess Bone Marrow With an Immunomagnetic Purging Procedure," and the
above-named chapter by Favrot et at, both in this volume). The feasibility of
purging is clearly demonstrated here in our patients. The continued
occurrence of marrow relapse despite purging might lead to the conclusion
that such procedures have little to contribute. However, we have laboratory
evidence that some purging procedures were incomplete (32,35; see also
Favrot et al. and I. Philip et al, both in this volume). Only case-by-case
analysis, using a clonogenic or liquid culture assay, can in the future identify
the need and determine the efficacy of the purging procedure. Our
preliminary conclusion is that purging techniques still require perfection at
the laboratory level and that their worth should not be judged on the basis of
incomplete procedures.
The indications for ABMT in Burkitt's lymphoma are, in our opinion,