Molecular quantitation of minimal residual disease in acute myeloid leukemia with t(8;21) can identify patients in durable remission and predict clinical relapse

Abstract

One of the most common translocations in acute myeloid leukemia (AML) is the t(8;21), which produces the fusion gene AML1-MTG8. We have developed a sensitive competitive reverse transcriptase-polymerase chain reaction (RT-PCR) assay forAML1-MTG8 transcripts, coupled with a competitive RT-PCR for the ABL transcript as a control to accurately estimate the level of amplifiable RNA. We have shown that AML1-MTG8 andABL transcripts have equal degradation rates. Thus, this method is useful for multicenter studies. We studied 25 patients with t(8;21) AML by means of serial analysis done on bone marrow (BM) and peripheral blood (PB) samples from 21 patients. Our analysis showed that, in general, a successful induction chemotherapy produces a reduction of 2 to 3 log in the level of AML1-MTG8, followed by a further 2 to 3 log after consolidation/intensification chemotherapy. Levels up to 1 × 103 and 1 × 102 molecules/μg of RNA in BM and PB, respectively, were compatible with durable remission. On the other hand, 5 patients with levels of 0.71 × 105to 2.27 × 105 molecules/μg of RNA in BM and 2.27 × 103 to 2.27 × 104 molecules/μg of RNA in PB had hematologic relapse within 3 to 6 months. Our data indicate that serial quantitation of AML1-MTG8 transcripts is useful in identifying patients at high risk of relapse and may offer an opportunity for clinical intervention to prevent hematologic relapse. This approach was applied successfully in a patient who had an allogeneic BM transplantation. We also suggest that PB may be used an alternative to BM for quantitating AML1-MTG8 transcripts.

Quantification of TEL–AML1 transcript for minimal residual disease assessment in childhood acute lymphoblastic leukaemia

“…None of these children relapsed, but the median follow-up was only 5´5 years. These MRD levels are not very different from those obtained for the whole group of patients in most clinical trials including ours (Brisco et al, 1994;Cave  et al, 1998;Coustan-Smith et al, 1998;van Dongen et al, 1998). MRD level is believed to reflect the in vivo sensitivity of leukaemia blasts to chemotherapy.…”

“…MRD studies that enabled the clinically relevant thresholds of residual blasts to be determined relied on the use of TcR or IgH rearrangements, which are DNA markers present at a rate of one copy per cell (Cave  et al, 1998;van Dongen et al, 1998). The copy number of a DNA marker can easily be related to either the number of cells or the amount of DNA studied.…”

“…The prognostic value of minimal residual disease (MRD) is well established in childhood acute lymphoblastic leukaemia (ALL), and an increasing number of protocols now take this parameter into account to tailor treatment (Brisco et al, 1994;Cave  et al, 1998;Coustan-Smith et al, 1998;van Dongen et al, 1998). Because it permits MRD monitoring in up to 90% of children with ALL, detection of clono-specific immunoglobulin (Ig) or T-cell receptor gene (TcR) rearrangements using polymerase chain reaction (PCR) amplification has been widely used, and large clinical trials assessing the value of MRD rely on this approach (Brisco et al, 1994;Cave  et al, 1998;van Dongen et al, 1998). When leukaemia cells have a translocation, another possibility is to monitor MRD by reverse transcription (RT) and PCR amplification of the fusion transcript associated with the translocation (Foroni et al, 1999).…”

“…Quantitative MRD evaluation has been shown to be necessary for prognosis evaluation in ALL (Brisco et al, 1994;Cave  et al, 1998;Coustan-Smith et al, 1998;van Dongen et al, 1998), and quantitative PCR assays are required for this purpose. Competitive PCR and real-time PCR are two main approaches that have been used to quantify specific RNA messengers (Freeman et al, 1999).…”

Determination of minimal residual disease in leukaemia patients

“…Early studies showed that these transcripts persist for more than 5 years of remission after the completion of treatment (Nucifora et al, 1993), a finding that could be explained by the expression of AML1-ETO transcripts in normal monocytes, B cells and haematopoietic colony forming cells (Miyamoto et al, 2000). Despite the lack of a strict association between AML1-ETO transcripts and AML cells, careful quantification of these transcripts can help to monitor MRD (Morschhauser et al, 2000;Tobal et al, 2000). MRD studies have also been done in patients with AML and other cytogenetic abnormalities, such as inv (16).…”