Blood, Vol. 93 No. 7 (April 1), 1999:
pp. 2420-2421
CORRESPONDENCE
Patients With Essential Thrombocythemia Do Not Express BCR-ABL
Transcripts
 |
LETTER |
To the Editor:
We read with interest the article by Blickstein et al,1 in
which marrow aspirates from 25 patients with Ph
essential thrombocythemia (ET) were examined by reverse
transcriptase-polymerase chain reaction (RT-PCR) for expression of
BCR-ABL transcripts: the authors found that 48% of patients were
PCR+. In a subsequent letter, Marasca et al2
were unable to confirm these observations: only 1 of the 20 (5%)
patients tested in their series showed BCR-ABL expression. These
contrasting experiences prompted us to examine our own patients with
ET, and we wish to report our results.
We investigated prospectively marrow aspirates referred to our
institution for cytogenetic analysis from 18 consecutive patients with
ET (5 men, 13 women; median age, 71 years; range, 38 to 92 years). All
patients fulfilled the criteria for diagnosis of ET defined by the
Polycythemia Vera Study Group (PVSG).3 Median platelet
count was 1,140 × 109/L (range, 756 to 1,462). All
patients were Ph by standard cytogenetic analysis: none
of the patients had received cytoreductive treatment at the time of
marrow sampling. RT-PCR was performed according to the method of Cross
et al,4 with a sensitivity of 1:105. All assays
were performed with appropriate controls and were repeated at least
twice. None of our patients was found to express BCR-ABL.
How can we reconcile our results with those of Blickstein et
al?1 The patient population we have studied is slightly
different from Blickstein's, particularly in regard to previous
treatment: only 3 of 27 patients in their study were newly diagnosed,
with the remaining patients having received hydroxyurea at time of study, whereas all of our patients were newly diagnosed. However, it is
hard to explain the discrepancy between our results and those of
Blickstein's on this basis, although the possibility of further
mutations, including BCR-ABL rearrangement, occurring with follow-up
cannot be excluded. Blickstein et al do not state whether any of the
three untreated patients they studied were BCR-ABL+, but
acquisition of the Ph chromosome has been described as a late change in
other myeloproliferative disorders,5 and it would certainly
be interesting to perform a sequential study on patients with ET to
determine whether BCR-ABL rearrangements can be acquired as a result of
the natural history of the disorder or secondary to treatment.
Our results are much more in keeping with those of Marasca's
group,2 although more stringent criteria for the diagnosis of ET were used in this series (patients with platelet counts <1,000 × 109/L were excluded). Technical differences
also seem unlikely to explain the discrepancy: precise details of the
RT-PCR methodology used may vary slightly between the studies, but the
assay sensitivities appear similar. We suggest that a larger study of
BCR-ABL expression in sequential marrow samples from Ph
ET patients is performed, with further alternative methodologies such
as fluorescence in situ hybridization and "quantitative" PCR
being applied to samples yielding positive results.
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ACKNOWLEDGMENT |
This work was undertaken by Salisbury Health Care, who received funding
from the NHS executive; the views expressed in this publication are
those of the authors and not necessarily those of the NHS executive.
Stuart Hackwell
Fiona Ross
Wessex Regional Genetics
Laboratory
Jonathan O. Cullis
Department of Laboratory
Medicine
Salisbury Healthcare NHS Trust
Salisbury, Wiltshire,
UK
| |
REFERENCES |
1.
Blickstein D, Aviram A, Luboshitz J, Prokocimer M, Stark P, Bairey O, Sulkes J, Shaklai M:
BCR-ABL transcripts in bone marrow aspirates of Philadelphia-negative essential thrombocythemia patients: Clinical presentation.
Blood
90:2768, 1997[Abstract/Free Full Text]
2.
Marasca R, Luppi M, Zucchini P, Longo G, Torelli G, Emilia G:
Might essential thrombocythemia carry Ph anomaly.
Blood
91:3084, 1998[Free Full Text] (letter)
3.
Murphy S, Iland H, Rosenthal D, Laszlo J:
Essential thrombocythemia: An interim report from the polycythemia vera study group.
Semin Hematol
23:177, 1986[Medline]
[Order article via Infotrieve]
4.
Cross NCP, Hughes TP, Feng L, O'Shea P, Bungey J, Marks DI, Ferrant A, Martiat P, Goldman JM:
Minimal residual disease after allogeneic bone marrow transplantation for chronic myeloid leukaemia in first chronic phase: correlations with acute graft-versus-host disease and relapse.
Br J Haematol
84:67, 1993[Medline]
[Order article via Infotrieve]
5.
Najfeld V, Geller M, Troy K, Scalise A:
Acquisition of the Ph chromosome and BCR-ABL fusion product in AML-M2 and t(8;21) leukemia: Cytogenetic and FISH evidence for a late event.
Leukemia
12:517, 1998[Medline]
[Order article via Infotrieve]
Response
We thank Stuart Hackwell and colleagues for bringing to our attention
their observation. Hackwell et al found that none of their 18 newly
diagnosed ET patients expressed BCR-ABL transcripts in their bone
marrow. The discrepancies between our observation and that of the
Salisbury group is quite puzzling since another group recently provided
support to our previous data: Singer et al1 reported that
63% of their ET patients carried BCR-ABL transcripts in peripheral
blood. These data are in accord with our updated findings that 48% of
40 bone marrow aspirates of hydroxyurea-treated Ph ET
patients were positive for BCR-ABL.2 In peripheral blood, 18% expressed BCR-ABL transcripts.2,3 It should be noted that our RT-PCR analysis in bone marrow aspirates and peripheral blood
was done according to the clinical protocol, ie, screening 1.25 × 106 cells.
It seems there is a spectrum of observations. On one end are healthy
adults who carry BCR-ABL transcripts in 1 to 10 in 108
peripheral blood leukocytes, presumed to be lost through normal cell
differentiation and death.4 On the other end are
Ph chronic myeloproliferative treated patients who
express the transcripts in bone marrow and/or peripheral
blood.1-3 The role of hydroxyurea in generation of
translocation and gene fusion is not clear because, on the one hand,
BCR-ABL transcripts were detected in healthy individuals,4
and on the other hand the potential effect of hydroxyurea on genomic
stability has not been excluded.
We agree with Hackwell et al that a larger group of sequential marrow
samples is needed to elucidate the natural history of BCR-ABL
transcripts in ET Ph patients, using fluorescence in
situ hybridization and quantitative PCR analysis as well.
Blickstein Dorit
Aviram Adina
Shaklai Mati
Division of Hematology
Beilinson Campus
Rabin Medical
Center
Petach Tikva, Israel
| |
REFERENCES |
1.
Singer IO, Sproul A, Tait RC, Soutar R, Gibson B:
BCR-ABL transcripts detectable in all myeloproliferative states.
Blood
92:427a, 1998 (abstr, suppl 1)
2. Aviram A, Blickstein D, Stark P, Luboshitz J, Bairey O,
Prokocimer M, Shaklai M: Significance of BCR-ABL transcripts in bone
marrow aspirates of Philadelphia-negative essential thrombocythemia
patients. Leuk Lymphoma (in press)
3.
Blickstein D, Aviram A, Luboshitz J, Bairey O, Shaklai M:
BCR-ABL transcripts in blood and bone marrow aspirates of patients with Philadelphia-negative essential thrombocythemia, polycythemia vera, and idiopathic myelofibrosis.
Blood
92:424a, 1998 (abstr, suppl 1)
4.
Bose S, Deininger M, Gora-Tybor J, Goldman JM, Melo JV:
The presence of typical and atypical BCR-ABL fusion genes in leukocytes of normal individuals: Biologic significance and implications for the assessment of minimal residual disease.
Blood
92:3362, 1998[Abstract/Free Full Text]
