Autologous Bone Marrow Transplantation - Blog Science Connections

744 Summary
limited occurrence of this disease, there is a strong need for cooperative
studies. Attempts to proceed in this way have stimulated the discussions on
improvements in the staging of the disease and on the identification of
prognostic factors.
Among the other solid tumors discussed during this symposium were
breast cancer, small cell cancer of the lung, melanoma, soft tissue sarcoma,
and glioblastoma.
It is apparent that for the disseminated solid tumors, the situation at
present is comparable to that in leukemia 15 to 20 years ago. Most of the
studies are of the phase I and 11 type, and the patient populations are those
with a very poor short-term prognosis (i.e., they have extensive and resistant
disease). The emphasis has to be entirely on the design of more effective
antineoplastic regimens. Purging of the bone marrow is at this time of
secondary importance only. If at all necessary, purging is not expected to
provide insurmountable problems in view of easily utilizable characteristics of
most solid tumor cells. Several speakers emphasized the essential role of
deliberate phase I studies for selecting the feasibility and tolerability of supradose
chemotherapy regimens with ABMT support. Since the rescue technology
with autologous bone marrow is now available, the maximally
tolerated doses of drugs with critical toxicity for the bone marrow have to be
established. This has to be done in patients with advanced disease, but once
tolerable dosages have been defined yielding significant response rates, a
shift to application in cases during an earlier phase of the disease will automatically
take place.
One such attempt was reported by Miser (from the National Cancer
Institute) who treated various sarcomas (Ewing, rhabdomyosarcomas, and
primitive neuroectodermal tumors) in 68 patients in first remission with five
cycles of vincristine, doxorubicin, and cyclophosphamide, followed by intensification
with TBI and ABMT.
The overall event-free survival rate of 30% at 48 months was not different
from that observed following conventional treatment of these poor-prognosis
patients. The conclusion was that the efficacy of TBI as adjuvant ABMT
therapy was not clear.
In view of the difficulties involved in seeking effective ablative regimens
for these various disseminated solid tumors, the need for realistic animal
models at this stage of the work was also stressed. Now that the specific
biological behavior of some human tumor types has become better known, it
is indeed necessary that transplantable animal tumors of the same histological
type be selected on the basis of closer resemblance to the corresponding
human tumors. The laboratory work required for such a selection is considerable,
but seems to be fully justified as the interest of the clinicians in this
area is currently growing.