A simplified minimal residual disease polymerase chain reaction method at early treatment points can stratify children with acute lymphoblastic leukemia into good and poor outcome groups.
BACKGROUND
Minimal residual disease is an important independent prognostic factor in childhood acute lymphoblastic leukemia. The classical detection methods such as multiparameter flow cytometry and real-time quantitative polymerase chain reaction analysis are expensive, time-consuming and complex, and require considerable technical expertise.


METHODS
We analyzed 229 consecutive children with acute lymphoblastic leukemia treated according to the GBTLI-99 protocol at three different Brazilian centers. Minimal residual disease was analyzed in bone marrow samples at diagnosis and on days 14 and 28 by conventional homo/heteroduplex polymerase chain reaction using a simplified approach with consensus primers for IG and TCR gene rearrangements.


RESULTS
At least one marker was detected by polymerase chain reaction in 96.4% of the patients. By combining the minimal residual disease results obtained on days 14 and 28, three different prognostic groups were identified: minimal residual disease negative on days 14 and 28, positive on day 14/negative on day 28, and positive on both. Five-year event-free survival rates were 85%, 75.6%, and 27.8%, respectively (p<0.0001). The same pattern of stratification held true for the group of intensively treated children. When analyzed in other subgroups of patients such as those at standard and high risk at diagnosis, those with positive B-derived CD10, patients positive for the TEL/AML1 transcript, and patients in morphological remission on a day 28 marrow, the event-free survival rate was found to be significantly lower in patients with positive minimal residual disease on day 28. Multivariate analysis demonstrated that the detection of minimal residual disease on day 28 is the most significant prognostic factor.


CONCLUSIONS
This simplified strategy for detection of minimal residual disease was feasible, reproducible, cheaper and simpler when compared with other methods, and allowed powerful discrimination between children with acute lymphoblastic leukemia with a good and poor outcome.
Scrideli
Carlos A
CA
Department of Pediatrics, Faculdade de Medicina de Ribeirão Preto, Ribeirão Preto, SP, Brazil. scrideli@fmrp.usp.br
Assumpção
Juliana G
JG
Ganazza
Mônica A
MA
Araújo
Marcela
M
Toledo
Silvia R
SR
Lee
Maria Lúcia M
ML
Delbuono
Elisabete
E
Petrilli
Antonio S
AS
Queiróz
Rosane P
RP
Biondi
Andrea
A
Viana
Marcos B
MB
Yunes
José A
JA
Brandalise
Silvia R
SR
Tone
Luiz G
LG
D000293:Adolescent; D015703:Antigens, CD / Q000032:analysis; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D005434:Flow Cytometry / Q000379:methods / Q000706:statistics & numerical data; D015321:Gene Rearrangement; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics; D007145:Immunoglobulin kappa-Chains / Q000235:genetics; D007223:Infant; D053208:Kaplan-Meier Estimate; D008297:Male; D015999:Multivariate Analysis; D018365:Neoplasm, Residual / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods* / Q000706:statistics & numerical data; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis* / Q000188:drug therapy; D011379:Prognosis; D016016:Proportional Hazards Models; D011948:Receptors, Antigen, T-Cell / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
D015703:Antigens, CD; D007143:Immunoglobulin Heavy Chains; D007145:Immunoglobulin kappa-Chains; D011948:Receptors, Antigen, T-Cell