|
|||||||||
|
|
|
|
|
|
|
|
|
|
|
CORRESPONDENCE We read with interest the report of Panzer-Grümayer
et al1 in which the authors showed that evaluation of
minimal residual disease (MRD) in childhood acute lymphoblastic
leukemia (ALL) by semiquantitative molecular methods on day 15 of
induction therapy can be implemented in their recently established
MRD-based stratification. The authors were able to identify after only
2 weeks of treatment a patient population of 20% who may benefit from
the least-intensive treatment. But for patients with higher levels of
day 15 MRD (greater than or equal to 10 We performed a quantitative analysis of MRD by means of the
real-time quantitative PCR (RQ-PCR). This approach is far more accurate
than semiquantitative analysis of MRD, which was used by
Panzer-Grümayer et al.1 We studied 17 children with
B-precursor ALL treated according to protocol VIII of the Dutch
Childhood Leukemia Study Group (DCLSG) in the Emma Children's
Hospital/AMC (Amsterdam, Netherlands). Immunophenotyping and
cytogenetic analysis were performed at diagnosis and relapse, according
to standard techniques. Nine patients were in continuous complete
remission (CCR), and 8 patients had relapsed (follow-up of at least 60 months after diagnosis). All patients received the same
induction therapy. Bone marrow samples of all patients, taken at day
15, at the end of induction therapy and before consolidation, were
analyzed for MRD with IGH- and TCRD-
rearrangements as PCR targets. For quantification of residual disease,
patient-specific forward primers complementary to the junctional
region, in combination with consensus reverse primers and consensus
Taqman probes (JH probes for IGH rearrangements and D Results of MRD levels obtained with RQ-PCR at the 3 time points are
shown in the Table. We found a
significant difference between MRD levels at day 15 of the patients in
CCR, compared with the relapsed patients (P < .05). MRD
levels after 15 days of chemotherapy were in the CCR group in the range
of 0%-1.9%, with one patient negative. For the patients who suffered
from relapse, the MRD levels at this time point were significantly higher (2.6%-73%). In agreement with Panzer-Grümayer et
al,1 all patients with rapid molecular response at day 15 (MRD level less than 10 In our group of patients, we also determined whether the combined
measurement of 2 time points was more predictive than a single time
point. The precise quantification of MRD levels enabled us to determine
the slope of the disappearance curve of the leukemic cells between
diagnoses, at day 15 and at week 5. Significant differences
for both CCR and relapsed patients were found by a linear regression,
performed on log transformed data (see Figure). The slopes were tested for
significance of differences (Graphpad Prism version 3.00, Graphpad, San
Diego, CA). The slopes of the patient group still in remission
and of the patient group that suffered a relapse were significantly
different from each other (P < .001). This confirms the
different clearance of residual cells in relapsed versus CCR patients.
In conclusion, our quantitative PCR results suggest that it might already be possible to discriminate between good- and poor-risk patients by precise quantification of MRD level at the end of induction therapy. But it has to be investigated in prospective studies whether indeed a clear cut-off level will be found. Furthermore, clinicians might prefer to perform stratification of therapy based on determination of MRD at 2 time points. Our results suggest that, although the start of consolidation can also be used as a second time point, quantitative MRD results at day 15 are already highly informative in this respect. The major advantage of this latter approach is the earlier availability of the prognostic information, and this information can be used to modify treatment according to risk group.
Valerie de Haas, Willem
References
1.
Panzer-Grümayer R, Schneider M, Panzer S, Fasching K, Gardner H.
Rapid molecular response during early induction chemotherapy predicts a good outcome in childhood acute lymphoblastic leukemia.
Blood.
2000;95:790-794 2. Verhagen OJ, Willemse MJ, Breunis WB, et al. Application of germline IGH-probes in real-time quantitative PCR for the detection of minimal residual disease in acute lumphoblastic leukemia. Leukemia. In press. 3. Van Dongen JJM, Seriu T, Panzer-Grümayer ER, et al. Prognostic value of minimal residual disease in acute lymphoblastic leukemia in childhood. Lancet. 1998;352:1731-1738[Medline] [Order article via Infotrieve].   CiteULike  Connotea  Del.icio.us  Digg  Reddit  Technorati What's this?
Related Article in Blood Online:
This article has been cited by other articles:
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
 |
 |
|||||||
 |
 |
 |
 |
 |
 |
 |
 |
||
| Copyright © 2000 by American Society of Hematology Online ISSN: 1528-0020 | |||||||||
2 or
10
3-probe for V
n B. Breunis, Onno J. Verhagen, Henk van den Berg, and C. Ellen van der Schoot
