Daniela Tozzuoli

Emergence of Ph negative clones in chronic myeloid leukemia (CML) patients in complete cytogenetic remission after therapy with imatinib mesylate (STI)

To the Editor: While clonal evolution with secondary cytogenetic abnormalities in addition to Ph-positive clones are seen in up to 60–80% of chronic myeloid leukemia (CML) patients who progress to advanced stages of the disease, cases with additional Ph-negative clones have only been rarely reported with interferon therapy (1). This seems to be more frequent in patients treated with imatinib than those undergoing other therapy regimens. Bumm et al. (2) investigated the clonality of CML patients after therapy with imatinib mesylate (3) using X-chromosome inactivation by polymerase chain reaction analysis of the human androgen receptor (HUMARA), showing that the majority of the complete cytogenetic responders had a polyclonal Ph) hematopoiesis. Interestingly, the authors reported the emergence of Ph-negative new clones in seven of 46 (15.2%) patients by conventional cytogenetics. In particular, alterations typically present in MDS or AML were found, i.e.+8, del(20q), )7, t(3:21). Andersen et al. (4) reviewed 17 patients from the literature who developed a Ph-negative unrelated clone after therapy with imatinib (eight patients) or other therapies (nine patients) including interferon, busulfan, hydroxurea and busulfan–melphalan with autologous bone marrow transplantation. In particular, 11 of 17 patients had a trisomy 8, two of these cases also had a monosomy 7 or del(7q), and other abnormalities involved chromosomes 5q, 13q, 11q. Interestingly, four of 17 patients, two of them with a +8, one with a +8 and )7, and one with a del(7q), developed acute myeloid leukemia (AML) or myelodysplasia (MDS). We would like to report our experience and make some comments on five of 29 CML patients (17.2%) treated at our institution who after imatinib mesylate developed novel Ph-negative clones in complete cytogenetic remission (CCR) after a mean time of 11 months (range 6–28) (Table 1). Three of the five patients had a +8 in 4–13 cells, one patient developed a novel t(6;7)(p24;q21), and the last case a dup (1)(q11q21). All patients were previously treated with hydroxurea (HU) or interferon (IFN) except for two. We did not see any sign of MDS, assessed both by pathologic examination of bone marrow aspirates and by peripheral blood count analysis. Our results are similar to those described in the literature, but surprisingly and of particular interest is that one of our patients had a +8 in Ph) and Ph+ cells, only once described in the literature, supporting the hypothesis of a clonal evolution. Patient no. 5 had a full disappearance of the Ph+ cells, maintaining the dup(1q) as the sole aberration after 6 months of therapy. Follow-up from the development of new clones is indicated in Table 1. Patients 3, 4, and 5 had just temporary new clones, as the clone disappeared in the subsequent analysis. In patients 1 and 2 the +8 was confirmed in a subsequent sample 3 months later. An interphase fluorescence in situ hybridization (i-FISH) study of the diagnosis samples in patients 1, 2 and 3 utilizing a CEP 8 probe (Vysis, Downers Grove, IL, USA) showed a mean of 3% (2–4) of cells with trisomy 8, under a normal cut-off value. All patients are alive, in good clinical condition, maintaining complete hematologic and cytogenetic remission. We believe that the number of patients could be underscored, possibly because of partial metaphase analysis, that is the search for the Ph chromosome only, instead of a full analysis of at least 20 cells in CML. At the moment the meaning and the mechanism of the emergence of additional clonal abnormalities is unclear. It may seem obvious that Ph+ cells have a proliferative advantage at diagnosis on other clonal cells and that imatinib not only discloses Eur J Haematol 2003: 71: 313–314 Printed in UK. All rights reserved Copyright Blackwell Munksgaard 2003

Molecular cytogenetic analysis of B-CLL patients with aggressive disease.

Abstract We tested a set of commercially available probes to determine the feasibility and accuracy of FISH in the detection of abnormalities in 13 patients with Chronic Lymphocytic Leukemia (CLL) with a particular aggressive clinical disease. We utilized three different probes for the 13q12-14 region, one for the centromeric region of chromosome 12, one for the P53 gene at 17p13.1 and one for 3′-5′ IGH at 14q32, covering the entire region of IGH, thus potentially allowing to detect more rearrangements. Conventional cytogenetic study showed a normal karyotype in 8/13 patients. FISH was able to detect chromosomal abnormalities in 10/13 pts (85%): +12 in 4 pts (38%); del 13q in 4 (38%); del 17p in 3 (35%); del of 5′-IGH in 1 (15%). In conclusion FISH confirmed its ability to improve the detection of cytogenetic abnormalities especially in patients with an aggressive disease.

The Use of Fluorescence In Situ Hybridization (FISH) in Chronic Lymphocytic Leukemia (CLL)

Abstract As a result of the low proliferative index, only 50% of chronic lymphocytic leukemia cases are adequate for cytogenetic analysis. Of these, about half have clonal abnormalities. The application of fluorescence in situ hybridization (FISH) to CLL has substantially enhanced our ability to detect chromosomal aberrations; the incidence of a number of recurring abnormalities has been established, providing new insights into the pathogenesis of this disease with a direct impact on the prognosis.

A novel t(6;7)(p24;q21) in a chronic myelocytic leukemia in complete cytogenetic remission after therapy with imatinib mesylate

Emergence of additional cytogenetic clones in chronic myelocytic leukemia (CML) patients who become Philadelphia chromosome-negative (Ph-) after alpha-interferon therapy (or more recently with imatinib mesylate) have been described. We report here a case of a novel t(6;7)(p21;q23) that developed in a CML patient in complete cytogenetic remission during imatinib therapy. In this case, fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction showed a normal pattern for BCR and ABL genes, suggesting that a different and unrelated clone developed after the disappearance of the Ph chromosome.

Trisomy 12 and t(14;22)(q32;q11) in a patient with B-cell chronic lymphocytic leukemia.

Abstract Recurrent cytogenetic abnormalities are typically found in about one third of B-cell chronic lymphocytic leukemia patients (B-CLL) by standard cytogenetic analysis and their prognostic relevance is well known. We report a case of a B-CLL patient showing both trisomy 12 and a t(14;22)(q32;q11). Trisomy 12 is often associated with aggressive disease and resistance to chemotherapy, however, our patient is in good health and currently untreated after 7 years, suggesting in this case a relatively good prognosis and a questionable role for translocations involving the 14q32 locus.