Minimal residual disease studies are beneficial in the follow-up of TEL/AML1 patients with B-precursor acute lymphoblastic leukaemia.
The t(12;21)(p13;q22) translocation has been identified as the most common chromosomal abnormality in childhood acute lymphoblastic leukaemia (ALL). Initially, several investigators reported an excellent prognosis in paediatric leukaemias with this translocation, but other studies showed a 20% incidence in relapsed ALL. We performed an extensive analysis of 90 ALL patients. In 17 (19%) cases a TEL/AML1 fusion was found. However, this group was not representative as it included a high number of relapsed patients compared with the normal incidence in B-precursor ALL [54 in continuous complete remission (CCR) and 36 relapsed patients] and only a slightly better prognosis for TEL/AML1-positive patients was found (not significant) (four relapses in 17 TEL/AML1-positive patients vs. 32 relapses in 73 TEL/AML1-negative patients). Comparison of known prognostic factors (age, sex, ploidy, white blood cell count and immunophenotype) between relapsed TEL/AML1-positive and TEL/AML1-positive patients in CCR did not reveal differences, except that the white blood cell count was significantly higher in the relapsed group (P = 0.001). Time between diagnosis and relapse was not different for the relapsed TEL/AML1-positive group vs. the relapsed TEL/AML1-negative group. In 11 TEL/AML1-positive patients, the minimal residual disease (MRD) level at the end of induction therapy was quantified in a limiting dilution assay using IGH or TCRD junctional regions as polymerase chain reaction (PCR) targets. In all four relapsed patients, the level of MRD at the end of induction therapy was high (range 0.24-1.2%), whereas in all seven CCR patients, the MRD level was extremely low (0.02 to < 0.001%). In agreement with previous studies in which MRD levels at the end of induction therapy were found to be the strongest risk factor independent of other risk factors, in the present study we show that the MRD level remains a risk factor independent of the presence of a TEL/AML1 fusion gene.
de Haas
V
V
Emma Kinderziekenhuis/AMC, University of Amsterdam, The Netherlands.
Oosten
L
L
Dee
R
R
Verhagen
O J
OJ
Kroes
W
W
van den Berg
H
H
van der Schoot
C E
CE
D002881:Chromosomes, Human, Pair 12; D002891:Chromosomes, Human, Pair 21; D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins / Q000235:genetics; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D018365:Neoplasm, Residual / Q000188:drug therapy / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D015452:Precursor B-Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy / Q000235:genetics*; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012008:Recurrence; D012097:Repressor Proteins; D014157:Transcription Factors / Q000235:genetics; D014178:Translocation, Genetic; D000097764:ETS Translocation Variant 6 Protein
D050676:Core Binding Factor Alpha 2 Subunit; D004268:DNA-Binding Proteins; D015514:Oncogene Proteins, Fusion; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins; D014157:Transcription Factors; D000097764:ETS Translocation Variant 6 Protein; C493728:RUNX1 protein, human