Chromosome analyses in chronic lymphocytic leukemia and related B-cell neoplasms

Treatment Approaches to Chronic Lymphocytic Leukemia With High-Risk Molecular Features

The clinical course of chronic lymphocytic leukemia (CLL) is highly variable. Over the past decades, several cytogenetic, immunogenetic and molecular features have emerged that identify patients suffering from CLL with high-risk molecular features. These biomarkers can clearly aid prognostication, but may also be capable of predicting the efficacy of various treatment strategies in subgroups of patients. In this narrative review, we discuss treatment approaches to CLL with high-risk molecular features. Specifically, we review and provide a comprehensive overview of clinical trials evaluating the efficacy of chemotherapy, chemoimmunotherapy and novel agent-based treatments in CLL patients with TP53 aberrations, deletion of the long arm of chromosome 11, complex karyotype, unmutated IGHV, B cell receptor stereotypy, and mutations in NOTCH1 or BIRC3. Furthermore, we discuss future pharmaceutical and immunotherapeutic perspectives for CLL with high-risk molecular features, focusing on agents currently under investigation in clinical trials.

Detection of clonal aberrations by cytogenetic analysis after different culture methods and by FISH in 129 patients with Chronic Lymphocytic Leukemia

There are only a few cytogenetic analysis (CA) studies that directly compare the novel cultivation technique using immunostimulatory CpG-oligonucleotide DSP30/interleukin-2 (DSP30/IL2) with other culture methods. Therefore, parallel cultures of peripheral blood of 129 chronic lymphocytic leukemia (CLL) patients were set up in unstimulated cultures, in the presence of pokeweed medium (PWM), and with DSP30/IL2. Furthermore, CA results were compared with data obtained by FISH. Clonal aberrations were observed by CA in 6% of the cases in unstimulated cultures, in 27% of the cases with PWM, and in 40% of the cases with DSP30/IL2. Some clonal aberrations were detected by CA only with one culture method. Using 3 different culture methods, clonal aberrations were detected in 41% of the cases by CA and in 71% of the cases by FISH. Altogether, 78% of the cases exhibited clonal aberrations discovered by CA and FISH. Also, CA detected clonal aberrations not targeted by FISH in 7% of the cases, and FISH identified clonal aberrations not detected by CA in 36% of the cases. Our study demonstrates that the combined use of CA with different culture methods together with FISH increases our knowledge of the genetic complexity and heterogeneity in CLL pathogenesis.

Chromosomal translocations and karyotype complexity in chronic lymphocytic leukemia: a systematic reappraisal of classic cytogenetic data

The significance of chromosomal translocations (CTRAs) and karyotype complexity (KC) in chronic lymphocytic leukemia (CLL) remains uncertain. To gain insight into these issues, we evaluated a series of 1001 CLL cases with reliable classic cytogenetic data obtained within 6 months from diagnosis before any treatment. Overall, 320 cases were found to carry ≥ 1 CTRAs. The most frequent chromosome breakpoints were 13q, followed by 14q, 18q, 17q, and 17p; notably, CTRAs involving chromosome 13q showed a wide spectrum of translocation partners. KC (≥ 3 aberrations) was detected in 157 cases and significantly (P < 0.005) associated with unmutated IGHV genes and aberrations of chromosome 17p. Furthermore, it was identified as an independent prognostic factor for shorter time-to-first-treatment. CTRAs were assigned to two categories (i) CTRAs present in the context of KC, often with involvement of chromosome 17p aberrations, occurring mostly in CLL with unmutated IGHV genes; in such cases, we found that KC rather than the presence of CTRAs per se negatively impacts on survival; (ii) CTRAs in cases without KC, having limited if any impact on survival. On this evidence, we propose that all CTRAs in CLL are not equivalent but rather develop by different processes and are associated with distinct clonal behavior.

PHA/IL2: an efficient mitogen cocktail for cytogenetic studies of non-Hodgkin lymphoma and chronic lymphocytic leukemia

This study documents the utility of a mitogen/cytokine cocktail composed of phytohemagglutinin and Interleukin 2 (PHA/IL2) used to stimulate cultures from patients with chronic lymphoproliferative disorders. We report the results of a selected series of 57 patients with non-Hodgkin lymphoma (NHL) or chronic lymphocytic leukemia (CLL), in which only the culture stimulated with PHA/IL2 demonstrated the presence of an abnormal clone. On average, cells in the abnormal clone comprised 40% of the mitotic cells in this culture. The most common abnormalities observed in these patients were trisomy 12, present in 39% of the cases, and t(14;18), seen in 14% of cases.

Frequency and implications of chromosome 8 and 12 gains in Ewing sarcoma

Ewing sarcoma (ES) is the second most common primary malignant tumor of bone in children and young adolescents. Most ES contain a pathognomonic translocation t(11;22)(q24;q12) that is likely a pivotal event in the tumorigenesis of these neoplasms. Many ES also contain nonrandom, numerical chromosomal aberrations, the most common of which are trisomies 8 and 12. In this study we evaluated the hypothesis that these trisomies might occur during neoplastic progression and might be associated with differences in biologic behavior. We tested this hypothesis using a combined cytogenetic and dual color fluorescence in situ hybridization approach to determine chromosome 8 and 12 copy number in 52 ES. Relative gains, primarily trisomies, of chromosomes 8 and 12 were found in 24 (46%) and 17 (33%) cases, respectively. Trisomy 8 and trisomy 12 were independent events acquired in a flexible order during ES genetic progression. Our preliminary findings also suggest a higher frequency of trisomies 8 and 12 in relapses than in primary tumors. Prospective studies will be required to determine whether either trisomy is prognostic in newly-diagnosed ES.

Monoallelic p53 deletion in chronic lymphocytic leukemia detected by interphase cytogenetics

Chromosomal aberrations can be detected in 50% of patients with chronic lymphocytic leukemia (CLL). A role for tumor suppressor genes in the genesis of lymphoid tumors has been reported. In B-CLL, p53 gene mutations were found in 10-15% of the patients. We used fluorescence in situ hybridization (FISH) to detect p53 deletion in B-CLL. We also correlated the cytogenetic findings with the clinical course. In situ hybridization to interphase nuclei showed monallelic p53 deletion in 6 of 23 patients (26%). The percentage of cells with one p53 signal ranged from 12 to 100. A statistically significant correlation between p53 deletion and progression of CLL was demonstrated. We conclude that FISH is a sensitive and reliable method to detect deletion of specific genes (i.e., p53) in CLL. The finding of p53 deletion is associated with disease progression.

Cytogenetic studies in seventy-six cases of B-chronic lymphoproliferative disorders

The results of cytogenetic studies are reported in 76 patients with B-chronic lymphoproliferative disorders (B-CLPD): 60 patients with chronic lymphocytic leukemia (CLL), six with follicular lymphoma in leukemic phase (FLLP), five with splenic B-cell lymphoma with villous lymphocytes (SLVL), two with chronic prolymphocytic leukemia (CPL), two with hairy cell leukemia (HCL), and one with plasma cell leukemia (PCL). PHA (phytohemagglutinin), PWM (pokeweed mitogen), LPS (lipopolysaccharide from Escherichia Coli), TPA (phorbol 12-myristate acetate), IL6 (interleukin 6), and DxS (dextran sulfate) were used as mitogens. Mitoses were obtained in 75 cases. Clonal aberrations could be demonstrated in 34 cases (44%). In CLL, classical type, chromosomes 6, 11, and 13 were more frequently involved, whereas trisomy 12 was frequently found in CLL mixed-cell type, in FLLP, and CPL. In SLVL the deletion del(7)(q32) is noteworthy and miscellaneous chromosome abnormalities in the remaining patients were observed. Regarding the efficiency of mitogens, PHA turned to be the most effective in obtaining metaphases and in detecting clonal chromosomal aberrations.

The BCL-1, BCL-2, and BCL-3 oncogenes are involved in chronic lymphocytic leukemia. Detection by fluorescence in situ hybridization

The putative oncogenes BCL-1, BCL-2, and BCL-3 are commonly rearranged by translocations to the immunoglobulin genes in B-cell malignancies. However, Southern blotting rarely detected their involvement in chronic lymphocytic leukemia (CLL). This discrepancy could stem from some unique features of the oncogenesis of CLL or be due to shortcomings of Southern blotting. We have therefore evaluated the role of fluorescence in situ hybridization (FISH) in the detection of these oncogenes in CLL. Twenty consecutive CLL patients were studied by FISH for the detection of BCL-1, BCL-2, or BCL-3 rearrangement and for the presence of trisomy 12. Selected patients were also evaluated by classical cytogenetic techniques and by Southern blot analysis. Juxtaposition of JH and BCL-1 was demonstrated in 10 (50%), BCL-2 in three (15%), and BCL-3 in four (20%) of the patients. Trisomy 12 was detected by FISH in 11 (55%) patients. The coexistence of trisomy 12 and translocation of the BCL-1 oncogene was common. Three of the patients had chromosomal aberrations compatible with those detected by FISH. In contrast, in none of the five patients selected by their positive FISH findings was a rearrangement demonstrated by Southern blotting. We conclude that FISH is a sensitive method for the detection of oncogene involvement in CLL. Mainly BCL-1, but also BCL-2 and BCL-3, are commonly translocated to the immunoglobulin heavy chain locus on chromosome 14. These translocations are often associated with trisomy 12. These findings indicate that the BCL oncogenes are commonly involved in CLL and lend support to the multi-hit theory of cancer development.

Phorbol-12,13-dibutyrate improves the quality of cytogenetic preparation in lymphoid malignancies

In cytogenetic preparation of lymphoid malignancies we investigated the quantitative and qualitative impact of phorbol-12,-13-dibutyrate (P) and of this tumor promoter in combination with the calcium ionophore A23187 (PA). Using parallel cultures of unstimulated and stimulated preparations, the effect was examined in 13 patients with malignant lymphomas and six patients with acute lymphoblastic leukemias (ALL). Focusing on high-quality analyzable metaphases, the best results were found in seven of 13 cases with lymphomas and five of six patients with ALL in the cultures supplemented with phorbol-12,13-dibutyrate. The yield of metaphases of good quality regarding length, spreading, and banding of chromosomes was regularly better in P-stimulated 24-hour culture (p < 0.05), followed by 48-hour cultures stimulated with P alone. Addition of the calcium-ionophore was of no further benefit. The yield of the unstimulated direct harvest was rather poor in nearly all patients investigated. Because no mutagenic effect of P was observed, the use of this mitogen may offer interesting perspectives in cytogenetic analysis of lymphoid malignancies and perhaps also in other tumors with low mitotic indexes.

Detection of bcl rearrangements in B-CLL by fluorescence in situ hybridization

Data concerning oncogene activation in CLL are very limited. When studied by Southern blot, rearrangements of bcl-1, bcl-2, and bcl-3 have been only infrequently reported. We evaluated the role of fluorescence in situ hybridization (FISH) in the detection of gene rearrangements in two CLL patients. We used multiple DNA probes, including those of chromosome 12, immunoglobulin heavy and light chains, and the oncogenes bcl-1, bcl-2, and bcl-3. Additionally, routine cytogenetic study was performed. In one patient, trisomy 12 and bcl-2 translocation were demonstrated by both methods, while trisomy 12 and bcl-1 translocation were seen in the second patient, who had a normal karyotype. Larger studies should evaluate the role of FISH in the detection of oncogene involvement in CLL and compare it with other molecular methods.

Cytogenetics in CLL and related disorders

Chromosome analysis of more than 1200 patients with chronic lymphocytic leukaemia reported to the International Working Party on Chromosomes in CLL and in the literature is analysed. Clonal chromosomal abnormalities are found in about half of the patients, and one third of those with clonal aberrations have trisomy 12, with or without additional changes. The most common structural abnormalities involve the long arm of chromosome 13, usually as deletions involving 13q14, the site of the retinoblastoma gene. Other recurrent abnormalities are deletions of the long arms of chromosome 11 and 6. 14q+ markers are frequent in patients at advanced stage, but are almost always within complex abnormalities. The number of clonal abnormalities in the CLL cells has a strong prognostic impact. Trisomy 12 as a single abnormality is an adverse prognostic sign, whereas patients with 13q abnormalities generally do comparatively well. Lymphoid leukaemia with monoclonal immunoglobulin secretion frequently involves clonal chromosomal abnormalities, and the type of change is similar to that seen in true CLL. In B cell prolymphocytic leukaemia, t(11;14) is a common finding, together with trisomy 12. T cell prolymphocytic leukaemia is characterized by an inversion of the long arm of chromosome 14, with breaks at q11 and q32, and trisomy of 8q, whereas large granular lymphocytic leukaemia has shown no consistent abnormality. Hairy cell leukaemia seems to involve a specific set of non-random chromosome abnormalities, such as inv(5)9.

Chromosomal analysis of purified B-chronic lymphocytic leukemia lymphocyte cultures: comparison with whole blood cultures and in situ hybridization

Chromosomal analysis of stimulated whole blood cells and purified B lymphocytes was performed in 13 stage A(0) and 1 stage C(IV) chronic lymphocytic leukemia (B-CLL) patients. Abnormal clones were found in 6 cases in purified B lymphocytes cultures and in a single one in whole blood cultures. In situ hybridization with a chromosome 12 probe was in accordance with the chromosomal analysis of purified B-CLL lymphocytes and not with the results obtained using whole blood culture. Cytogenetic analysis of isolated B cells is simple and sensitive. It enhances the detection of abnormal clones in B-CLL and applied to larger series of patients, it should allow a precise evaluation of the incidence of chromosomal abnormalities in CLL and of their clinical (prognostic) significance.

In situ hybridization: a simple and sensitive method for detection of trisomy 12 in chronic lymphocytic leukemia

Chromosome aberrations are detected in only 50% of patients with chronic lymphocytic leukemia (CLL), owing usually to the low mitotic rate exhibited by the neoplastic lymphocytes. Fluorescence in situ hybridization (FISH) is a simple method for identifying numerical abnormalities of the target chromosome in interphase nuclei. Therefore, we used the FISH procedure with chromosome 12-specific a-satellite probe to evaluate 19 patients with CLL. Trisomy 12 was detected in interphase cells of 12 patients (63%). Cytogenetic analysis, performed in nine patients, yielded trisomy 12 in four (44%). FISH detected three patients with trisomy 12 in whom conventional cytogenetic method yielded a normal karyotype. FISH is a simple, reliable, and sensitive method for detection of trisomy 12 in patients with CLL.