Extensive submicroscopic deletions adjacent to the breakpoint on derivative chromosome 9 [der(9)] have been reported in a subset of Chronic Myeloyd Leukemia (CML) patients and have been associated with an adverse outcome with conventional drugs and α-interferon (α-IFN). Huntly et al (

Blood.
2003
;
102
.
2205
–12
) reported 275 CML pts who were treated with imatinib in CP, suggesting that der(9) deletions were associated with lower response rates and a shorter time to progression. Different data were reported by Quintas-Cardama et al (
Blood.
2005
;
105
:
2281
–6
), who did not find any difference related with der(9) deletions in other 320 patients treated with imatinib. In these 2 studies, some patients began imatinib in early CP (51 and 152, respectively) while many patients (224 and 168, respectively) were treated in late CP. To establish the relationship of der(9) deletions with the response to imatinib in early CP patients, we planned a prospective study involving 3 consecutive multicentric national studies of the GIMEMA (Gruppo Italiano Malattie Ematologiche dell’Adulto) CML Working Party. 421 CML patients in early chronic phase were enrolled between January, 2004 and January, 2006; Fluorescence in situ hybridization (FISH) analysis of bone marrow cells was performed using BCR/ABL extra-signal, D-FISH or dual-color dual-fusion probes. At diagnosis, 52 (12%) of them had der(9) deletion and 369 (88%) had not. The 2 groups, with/without deletions, were comparable (no difference in age, Sokal risk, imatinib dose). Median observation time is 12 months. At 3 months, the CHR rates in with/without deletions patients were 87%/92%. At 6 months, the complete cytogenetic response (0% Ph-pos; CCgR) rates were 80%/80%, with major molecular response (MMolR, defined as a Bcr-Abl/Abl x 100 ratio < 0.1%) rates of 52%/51%, respectively. At 12 months, CCgR rates were 89%/86% and MMolR 52%/61%. No difference is significant. We conclude that the presence of der(9) deletions at diagnosis do not constitute a negative factor for response to imatinib: the haematological, cytogenetic and molecular response rates resulted equal between the 2 groups of patients with and without der(9) deletions. This finding is relevant to the long term effect of imatinib treatment, since both the CCgR and the MMolR are important and established indicator of long term survival.

Topics:
chromosomes, human, pair 9, imatinib mesylate, leukemia, myeloid, chronic-phase, bcr-abl tyrosine kinase, brachial plexus neuritis, human leukocyte interferon, interferons, leukemia, time to progression, fluorescent in situ hybridization

Disclosure: No relevant conflicts of interest to declare.

ACKNOWLEDGMENTS: COFIN 2003, FIRB 2001, A.I.R.C., C.N.R., Fondazione del Monte di Bologna e Ravenna, LeukemiaNet founds, A.I.L.

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2006, The American Society of Hematology
2006
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