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X Chen1, Q Pan1, P Stow1, FG Behm2, R Goorha3,4, C-H Pui1,2,4 & GAM Neale1,2,4
1Department of Hematology/Oncology, St Jude Children's Research Hospital, Memphis, TN, USA
2Department of Pathology, St Jude Children's Research Hospital, Memphis, TN, USA
3Department of Virology and Molecular Biology, St Jude Children's Research Hospital, Memphis, TN, USA
4University of Tennessee College of Medicine, Memphis, TN, USA
Correspondence to: G Neale, Department of Hematology/Oncology, St Jude Children's Research Hospital, 332 N Lauderdale, Memphis TN 38105, USA; Fax: 901 495 3749
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Hematologic relapse remains the greatest obstacle to the cure of children with acute lymphoblastic leukemia (ALL). Recent studies have shown that patients with increased risk of relapse can be identified by measuring residual leukemic cells, called minimal residual disease (MRD), during clinical remission. Current PCR methods, however, for measuring MRD are cumbersome and time-consuming. To improve and simplify MRD assessment, we developed a real-time quantitative PCR (RQ-PCR) assay for detection of leukemic cells that harbor the TAL-1 deletion. We studied serial dilutions of leukemic DNA and found the assay had a sensitivity of detection of one leukemic cell among 100 000 normal cells. We then investigated 23 samples from eight children with ALL in clinical remission. We quantified residual leukemic cells by using the TAL-1 RQ-PCR assay and by using limiting dilution analysis. In 17 samples, both methods detected MRD levels 0.001%. The percentages of leukemic cells measured by the two methods correlated well (r2 = 0.926). In the remaining six samples, both methods detected fewer than 0.001% leukemic cells. We conclude the TAL-1 RQ-PCR assay can be used for rapid, sensitive and accurate assessment of MRD in T-lineage ALL with the TAL-1 deletion. Leukemia (2001) 15, 166–170.
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