Autologous Bone Marrow Transplantation - Blog Science Connections

26 First-Remission Autograft forAML
RELATIONSHIP OF PREAUTOGRAFT INTERVAL TO
LEUKEMIA-FREE SURVIVAL
To examine the relevance of preautograft delay, we reviewed our experience
combined with that of six other series that have been reported.
The data were from 95 patients whose characteristics are shown in Table 1.
Cyclophosphamide plus TBI was the chosen ablative protocol for 58 patients;
23 received high-dose combination chemotherapy, and 14 underwent double
autografts and high-dose chemotherapy. No measures were taken to treat the
autograft in vitro in an attempt to remove residual leukemia. Twenty-nine
patients experienced relapse, all but two of these occurring within 12 months of
the autograft. Five patients died of causes other than leukemia. Figure 2 shows
the overall predicted survival and leukemia-free survival rates at 5 years.
The period of remission that had elapsed before the autograft was
variable, even within treatment centers, in this group of patients. To assess the
influence of preautograft delay on leukemia-free survival, the patients were
divided into groupings whose delay was 0-4 months, 5-8 months, and 9-12
months. Excluded from the analysis were patients whose delays were longer
than 12 months and patients who died of reactions.
Predicted disease-free survival rates shown in Figure 3 are for the 31 patients
in the 0- to 4-month delay group, 40 patients in the 5- to 8-month delay group, and
for the 14 patients in the 9- to 12-month delay group.
DISCUSSION
As a strategy for maintaining remission in AML and an alternative to
traditional chemotherapy, ablative treatment necessitating ABMT clearly merits
consideration. Although 40-50% of patients have relapsed, relapses have been
uncommon beyond 12 months after the autograft, suggesting that the pattern of
relapse previously observed with chemotherapy is altered. Since the relapse rate
so far is not higher than that of syngeneic-graft recipients with AML* in first
remission, there is little reason to believe that problems of leukemia contamination
of the autograft will be a priority in the immediate future. Preliminary clinical
results of efforts to purge the marrow do not yet show an advantage over the
unpurged results (7).
Current results of autograft are encouraging and the toxicity is acceptable.
Autograft may be more tolerable for patients and a better use of treatment
resources than the alternatives of prolonged intensive chemotherapy (13,14).
Improved methods of eradicating residual disease in the patient seem tobe a
concern of immediate priority. Although augmented TBI has been relatively
ineffective in reducing the relapse rate of patients who received allografts during
relapse (15), these may be more successful if applied during remission.
Equivalent chemotherapy used with allografting during first and second remissions
has an impressive record of eradicating residual disease (16).