A prospective study of minimal residual disease in childhood B‐lineage acute lymphoblastic leukaemia: MRD level at the end of induction is a strong predictive factor of relapse

Abstract

Summary. We prospectively investigated minimal residual disease (MRD) in 51 children with B-lineage acute lymphoblastic leukaemia (ALL) treated according to the Fralle 93 protocol. PCR follow-up was performed in children in morphological and cytogenetic complete remission, provided an immunoglobulin (IgH) gene rearrangement could be detected using FR3/J H amplimers. MRD was studied according to our previously described methodology, with a few modifications including the use of a consensus J H probe to control for PCR efficiency variations.Out of the initial 51 patients, 34 were assessable for MRD at the end of induction at the time of analysis. MRD levels were as follows: >1/10 3 in 26%, 1/10 3 to 1/10 4 in 50% and <1/10 4 or not detectable in 24%. With a median follow-up of 20 months there were five relapses, all of which occurred in the group of patients with MRD >1/10 3 . To date, none of the patients with MRD р1/10 3 (good molecular responder) has relapsed. Classification according to molecular response at the end of induction did not correlate with the conventional risks groups: there were no statistically significant differences between good and bad molecular responders. Of particular interest is the absence of correlation between WBC at diagnosis and MRD level at the end of induction. We conclude that classification of patients into good and bad molecular responders using PCR seems to be a better prognostic indicator than conventional risk factors in childhood B-lineage ALL. Patients with MRD level >1/10 3 have a particularly poor outcome and should always be considered for alternative therapeutic strategies in the future, whereas in good molecular responders belonging to poor or intermediate risk categories, treatment de-escalation might be contemplated.

Peripheral blood stem cell contamination in mantle cell non-Hodgkin lymphoma: the case for purging?

“…25,26 As long as the original rearranged band persisted, which in our hands corresponds to a percentage of at least 1%, no further analysis was performed and contamination was estimated using the value of the peak ( Figure 1). When no signal was observed (corresponding to fewer than 1% malignant cells), a semiquantitative PCR assay was done as described previously [21][22][23] to verify whether MCL cells were still detectable, the sensitivity of the method being 1:10 4 to 1:10 5 ( Figure 2). If residual malignant cells were identified, a LDA, derived from methods described by other authors 27,28 was performed, to better evaluate the number of residual lymphoma cells.…”

“…21 When amplification could be done with FR3/JH, a probe was directly made according to our previously described method. [21][22][23] In parallel, sequencing of the CDR-III region was performed according to the method used in the laboratory 24 which consists of a direct fluorescence-based methodology with the Prism Sequenase Terminator Single-Stranded DNA Sequencing kit and the ABI 373 apparatus (Applied Biosystems, Foster City, CA, USA). This allowed designing an allele-specific oligomer (ASO) matching the D-N-J sequence for use in a limiting dilution analysis (LDA).…”

Comparison of methods for assessment of minimal residual disease in childhood B-lineage acute lymphoblastic leukemia

“…Detection of monoclonality by PCR is also relatively simple and has a level of detection of approximately 10 −3 , a level which virtually all groups agree will identify high-risk patients. [1][2][3][4][5][6][7][8] In early studies of ANZCCSG Study V patients (treated 1985-1989), using material scraped from fixed stained bone marrow smears we reported that detection of monoclonality on day 35, by electrophoresis on standard polyacrylamide gels and subsequent staining, had a positive predictive value for relapse of 37.5%. Using fluorescent consensus primers and Genescan, detection of monoclonality after 20 weeks of treatment was reported to have a positive predictive value of 89% and a sensitivity of 57%.…”

“…[1][2][3][4][5][6][7][8][9] The hope for the future is that this information may be used to guide and improve treatment. A variety of techniques have been used for studying MRD.…”

Flow cytometry and allele-specific oligonucleotide PCR are equally effective in detection of minimal residual disease in ALL

“…[1][2][3] The persistence of high levels of MRD is associated with poor outcome and generally predicts clinical relapse. [4][5][6][7][8][9] A unique pattern of junctional regions of rearranged immunoglobulin heavy chain (IgH) and T cell receptor (TcR) genes has been widely applied as leukemia-or patient-specific targets for Southern blot or polymerase chain reaction (PCR)-based MRD analysis (reviewed in Refs 1,3). The sequences of junctional regions have been determined at diagnosis and sequence-specific oligonucleotides have been designed for further use as patient-specific primers.…”