CML Heads Up !
CML Bouys

Efficiency of interphase fluorescence in situ hybridization for BCR/ABL on peripheral blood smears for monitoring of CML patients: a comparison with bone marrow findings.

Akel S, Kolialexi A, Mavrou A, Metaxotou C, Loukopoulos D, Yataganas X.

First Department of Medicine, University of Athens School of Medicine, Athens, Greece. sakel@ncifcrf.gov

Conventional cytogenetic analysis (CCA) is the standard method for monitoring of the Philadelphia (Ph) chromosome in chronic myeloid leukemia (CML). Evaluation of breakpoint cluster region/abelson murine leukemia (BCR/ABL) fusion using interphase fluorescence in situ hybridization on peripheral blood smears (PB-FISH) might be another approach allowing more frequent and less invasive follow-up investigations.

Herein, BCR/ABL fusion gene was assessed on 21 PB smears from 16 CML patients in chronic phase. Results of PB-FISH were compared with those of CCA and interphase FISH on bone marrow aspirates (BM-FISH). PB-FISH analysis was combined with CD3 immunophenotyping that allowed simultaneous investigation of the
leukemic status of CD3(+) T lymphocytes and scoring CD3(-) cells for
BCR/ABL fusion gene. Moreover, the frequency of BCR/ABL fusion in nonlymphoid PB cells was estimated according to the differential leukocyte counts.

The incidence of BCR/ABL(+) fusion signals in CD3(+) T cells of CML patients was 5.3% (SD +/- 1.9) and did not exceed the normal cut-off value of 8%.

A significant correlation (P < 0.001) was found between results of PB-FISH and methods of BM analysis (CCA or BM-FISH).

Correction of PB-FISH results to include only nonlymphoid or CD3(-) cells reduced the mean of differences and improved agreement between PB-FISH and CCA or BM-FISH methods.

The best agreement was noted between CCA and PB-FISH on nonlymphoid cells. On the other hand, results of BM-FISH agreed well with those of PB-FISH on CD3(-) cells.

These findings imply that PB-FISH on nonlymphoid or CD3(-) cells is reliable and may replace BM analysis for monitoring of response to treatment in CML patients.


Back to Discussion

Third abstract discussed (K Richland)

[4847] Sequential Monitoring of the Philadelphia Chromosome in CML by FISH Reveals Transient Responses to Imatinib Mesylate (STI571) Treatment Not Detected by Metaphase Cytogenetics.

Leif L. Stenke, Lotta Ohm, Ingrid Arvidsson, Martin Höglund, Bengt Simonsson, Robert Hast.

Dept of Medicine, Div of Hematology, Karolinska Hospital and Institute, Stockholm, Sweden; Dept of Medicine, Div of Hematology, Uppsala University Hospital, Uppsala, Sweden

The Bcr-Abl tyrosine kinase inhibitor STI571 (imatinib mesylate) induces complete hematological responses in over 90% of patients with chronic phase chronic myeloid leukemia (CML) and complete cytogenetic responses (CCR) by conventional metaphase cytogenetics (CG) in over 30%. Since fluorescence in situ hybridization (FISH) is a more sensitive technique to study the penetration to the bone marrow of the Philadelphia (Ph) clone, we wanted to compare response evaluation by CG to FISH during STI571 treatment.

Bone marrow specimens were obtained from 9 interferon-failing chronic-phase CML patients (5M/ 4F; median age 58 yrs, range: 37-78), before and during STI571 treatment at 3, 6, 9, 12, and 15 months. The Ph chromosome expression in interphase cells was examined utilizing a dual color DNA probe (LSI bcr-abl ES, Visys, IL). The lower detection limit for a positive FISH sample was set to 1% (mean of 5 normal controls +3xSD). The initial STI571 dose (400 mg in 8 cases, 600 mg in 1 case) was subsequently reduced in 6 of the patients by 33-75% due to neutropenia.

All patients had complete hematological responses within 2 months of therapy. CG at follow-up after 12-15 months showed 3 complete cytogenetic responses (CCR), 1 major (MCR), 1 minor (mCR), and 4 no responses (NCR). The 3 CCR and 1 MCR patients all responded cytogenetically within 3-6 months. FISH supported the outcome of CG in all CCR/MCR  cases, the 3 CCR patients exhibiting <1% and the MCR patient <10% Ph+ bone marrow cells. The mCR and NCR patients showed 63-100% Ph+ bone marrow cells by CG in all samples during follow-up. When examined by FISH, 4 of the 5 mCR/NCR patients displayed a significant, but transient, reduction of Ph-expression where the initial percentage of Ph+ bone marrow cells were more than halved after 3-9 months of STI571 treatment . In these patients, the mean percentage (±SD) Ph+ cells was 58.7 (±7.2) before treatment, 22.0 (±11.3) at nadir, and 55.8 (±7.1) at 12-15 months after start of STI571 (p<0.001). In at least 2 patients recovery of the Ph+ clone seemed to be linked to the reduction of the initial STI571 dose.

We conclude, that FISH can reveal cytogenetic responses to imatinib mesylate treatment not detectable by metaphase CG in chronic phase CML patients. The clinical significance of this finding remains unclear. The transient nature of the responses may be related to reduction of the treatment dose rather than to development of true cellular resistance to imatinib mesylate.

Search the mariners faq and glossary
database

Join us in an on-line community

Join d discussion forum

Cml ahoy !