Detection of bcr/abl transcripts by RT-PCR and their colorimetric evaluation in chronic myeloid leukemia patients receiving allogeneic bone marrow transplantation.
BACKGROUND
Chronic myeloid leukemia (CML) is a disease characterized by the presence of a unique molecular marker, i.e. the fusion gene bcr-abl and its mRNA and protein products. This marker permits minimal residual disease follow-up after bone marrow transplantation (BMT) through cytogenetic or molecular analysis. Although the reverse transcriptase polymerase chain reaction (RT-PCR) method is largely employed, the clinical value and impact of a positive RT-PCR as a herald of hematological relapse has not yet been definitively ascertained.


METHODS
In order to verify the frequency of bcr-abl positivity in CML patients who underwent alloBMT, we performed serial two-step RT-PCR on 63 peripheral blood and bone marrow specimens obtained at different times after non T-cell-depleted BMT from 16 CML patients treated in our Institution. After amplification, RT-PCR products were always checked by liquid hybridization with a specific probe. Median molecular follow-up after BMT was 38 months (range 2-144 months).


RESULTS
None of the patients studied presented clinical hematological relapse after BMT. Six out of sixteen patients were found to be positive for bcr-abl. PCR positivity appeared in 4/6 patients more than one year post-BMT and in 2/6 patients within one year post BMT. In both instances PCR was an isolated finding in 5/6 patients and reverted to negativity in subsequent analysis; only one case was PCR-positive twice. It is noteworthy that RT-PCR positivity appeared in five patients presenting acute or chronic graft versus host disease (GVHD) and in one patient who had received MUD-BMT.


CONCLUSIONS
In our cohort of patients, transient bcr-abl positivity had no clinical relevance and was also found in MUD-BMT without heralding hematological relapse. Our observations further stress the importance of applying only quantitative PCR methods during the post BMT follow-up of CML patients.
Santini
V
V
Department of Hematology, University of Florence, Italy. santini@cesit1.unifi.it
Zoccolante
A
A
Bosi
A
A
Guidi
S
S
Saccardi
R
R
Vannucchi
A M
AM
Martinazzo
G
G
Bernabei
P A
PA
Ferrini
P R
PR
D000293:Adolescent; D000328:Adult; D016026:Bone Marrow Transplantation; D003124:Colorimetry; D005069:Evaluation Studies as Topic; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000235:genetics*; D006801:Humans; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000378:metabolism / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D016133:Polymerase Chain Reaction / Q000379:methods*; D012333:RNA, Messenger / Q000032:analysis*; D012194:RNA-Directed DNA Polymerase; D014184:Transplantation, Homologous
D012333:RNA, Messenger; D016044:Fusion Proteins, bcr-abl; D012194:RNA-Directed DNA Polymerase