Prognostic significance of chromosome abnormalities in chronic lymphocytic leukaemia

The molecular map of CLL and Richter's syndrome

Clonal expansion of B-cells, from the early stages of monoclonal B-cell lymphocytosis through to chronic lymphocytic leukemia (CLL), and then in some cases to Richter's syndrome (RS) provides a comprehensive model of cancer evolution, notable for the marked morphological transformation and distinct clinical phenotypes. High-throughput sequencing of large cohorts of patients and single-cell studies have generated a molecular map of CLL and more recently, of RS, yielding fundamental insights into these diseases and of clonal evolution. A selection of CLL driver genes have been functionally interrogated to yield novel insights into the biology of CLL. Such findings have the potential to impact patient care through risk stratification, treatment selection and drug discovery. However, this molecular map remains incomplete, with extant questions concerning the origin of the B-cell clone, the role of the TME, inter- and intra-compartmental heterogeneity and of therapeutic resistance mechanisms. Through the application of multi-modal single-cell technologies across tissues, disease states and clinical contexts, these questions can now be addressed with the answers holding great promise of generating translatable knowledge to improve patient care.

B-prolymphocytic leukemia: Is it time to retire this entity?

B-prolymphocytic leukemia (B-PLL) is included as a distinct entity in the current World Health Organization classification of hematolymphoid neoplasms. However, the diagnosis of B-PLL has presented several challenges since its conception, and over the past decades investigations of B-PLL have revealed substantial biologic and molecular heterogeneity. These data have shown that many B-PLL cases present many similarities with other types of small B-cell lymphomas, and that small B-cell lymphomas can undergo prolymphocytoid transformation. As a result, the frequency of B-PLL has markedly decreased, and currently B-PLL is a very rare entity. Most recent studies focused on B-PLL cases have been conducted on limited cohorts, precluding robust conclusions. In this article, we provide a concise historical review of B-PLL and describe the diagnostic and clinical challenges associated with establishing this diagnosis. We also argue that cases currently classified as B-PLL are unlikely to be a unique biologic entity, but rather represent a state of morphologic transformation characterized by many prolymphocytes that is shared by various types of small B-cell lymphoma.

The complex karyotype and chronic lymphocytic leukemia: prognostic value and diagnostic recommendations

Chromosomal abnormalities are frequently observed in patients with chronic lymphocytic leukemia (CLL) and have prognostic value. Deletions of the short arm of chromosome 17 (and/or mutations TP53) predict resistance to chemoimmunotherapy and shorter progression-free survival after targeted therapies. Although the complex karyotype (CK) is strongly predictive of a poor prognosis in hematologic malignancies such acute myeloid leukemia or myelodysplastic syndrome, its value in CLL is subject to debate. Here, we review the literature on the CK in CLL and examine its prognostic value with different treatments. We also propose a standardized method for defining a CK in all types of hematopoietic neoplasm.

Impact of Fluorescent In Situ Hybridization Aberrations and CLLU1 Expression on the Prognosis of Chronic Lymphocytic Leukemia: Presentation of 156 Patients from Turkey

OBJECTIVE

This study evaluates the impact of CLLU1 expression and fluorescent in situ hybridization (FISH) analysis of a group of Turkish chronic lymphocytic leukemia (CLL) patients.

MATERIALS AND METHODS

A total of 156 CLL patients were analyzed by FISH method; 47 of them were also evaluated for CLLU1 expression. Results were correlated with clinical parameters.

RESULTS

FISH aberrations were found in 62% of patients. These aberrations were del13q14 (67%), trisomy 12 (27%), del11q22 (19%), del17p (8%), and 14q32 rearrangements (20%). Overall del11q22 and del17p were associated with the highest mortality rates, shortest overall survival (OS), and highest need for medication. Homozygous del13q14, 14q32 rearrangements, and higher CLLU1 expression correlated with shorter OS.

CONCLUSION

Cytogenetics/FISH analysis is still indicated for routine evaluation of CLL. Special consideration is needed for the poor prognostic implications of del11q22, del17p, 14q32 rearrangements, and homozygous del13q14. The impact of CLLU1 expression is not yet clear and it requires more data before becoming routine in genetic testing in CLL patients.

Cytogenetic and flow cytometry evaluation of Richter syndrome reveals MYC, CDKN2A, IGH alterations with loss of CD52, CD62L and increase of CD71 antigen expression as the most frequent recurrent abnormalities

OBJECTIVES

Richter syndrome (RS) is a transformation of chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) into high-grade lymphoma. There are only limited data on flow cytometry (FCM) and cytogenetics in RS.

METHODS

In this study, FCM, classic cytogenetics (CC), and fluorescence in situ hybridization (FISH) were performed in eight RS cases.

RESULTS

Most cases of RS were characterized by a loss/decrease of CD52 and CD62L and increased CD71 expression. CC identified complex karyotypes, with losses of 9/9p and 17/17p as the most frequent in four of seven cases. Seven RS cases demonstrated MYC abnormalities. Disruptions of CDKN2A and IGH were identified in five of seven and four of seven RS cases, respectively.

CONCLUSIONS

Newly diagnosed RS is an oncologic emergency, and a quick diagnostic decision is crucial in clinical practice. Therefore, in patients with CLL/SLL and rapidly enlarging asymmetric lymphadenopathy and/or extranodal tumors, we strongly advise FCM of fine-needle aspiration biopsy (FNAB) material, including CD62L, CD52, and CD71 analysis as well as assessment of karyotype and at least MYC abnormalities by FISH of the same FNAB material. Loss of CD52 expression in RS most likely predicts resistance to alemtuzumab therapy, which is frequently used in CLL.

Outcomes of first-line treatment for chronic lymphocytic leukemia with 17p deletion

Although uncommon in treatment-naive patients with chronic lymphocytic leukemia, deletion 17p is a high-risk disease characteristic. We analyzed and reported outcomes for 63 patients with deletion 17p chronic lymphocytic leukemia who received first-line therapy at our institution; at time of first treatment, 81% had unmutated immunoglobulin heavy chain variable gene and 58% had complex karyotype. Forty-nine patients (76%) received first-line fludarabine, cyclophosphamide, rituximab-based therapy, 6 (11%) received rituximab-based and 8 (13%) received lenalidomide-based treatment. Overall, the complete plus nodular partial remission rate was 33%; on multivariable model, higher complete plus nodular partial remission rate was observed in patients with less than 50% cells positive for deletion 17p, and a higher probability of achieving at least a partial remission was observed with fludarabine, cyclophosphamide, rituximab-based treatment. After a median follow up of 33 months (range 1-89 months), the estimated median progression-free survival was 14 months (95% confidence interval 10-18) and estimated median overall survival was 63 months (95% confidence interval 43-83). In multivariable analysis, factors independently associated with longer progression-free survival were response to treatment and absence of complex karyotype. Achievement of complete plus nodular partial remission rate and mutated immunoglobulin heavy chain variable gene were independently associated with longer overall survival in multivariable model. Complex karyotype was associated with increased risk for Richter's transformation. New first-line strategies and agents must aim at both improving response and maintaining remission in patients with deletion 17p, particularly in the presence of complex karyotype.

TP53 aberrations in chronic lymphocytic leukemia

CLL patients harboring TP53 defects remain the most challenging group in terms of designing rational and effective therapy. Irrespective of the treatment employed-chemotherapy, chemoimmunotherapy, or pure biological drugs-median survival of these patients does not exceed 3-4 years. This adverse outcome is caused by a less effective response to therapeutics acting through DNA damage induction and relying on the subsequent initiation of apoptosis as well as by virtually inevitable aggressive relapse. Patient proportions with TP53 defects at diagnosis or before first therapy were reported within the range 5-15 %, but they increase dramatically in pretreated cohorts (reported up to 44 %), and also in patients with Richter transformation (50 % harbor TP53 defects). Currently, most laboratories monitor TP53 defect as presence of 17p deletion using I-FISH, but 23-45 % of TP53-affected patients were shown to harbor only mutation(s). In other patients with intact TP53, the p53 pathway may be impaired by mutations in ATM gene coding for the p53-regulatory kinase; however, prognosis of ATM-defective patients is not as poor as those with TP53 abnormalities. Though many novel agents are under development, the monoclonal antibody alemtuzumab and allogeneic stem cell transplantation remain the basic treatment options for TP53-affected CLL patients.

What is the best frontline therapy for patients with CLL and 17p deletion?

Chronic lymphocytic leukemia (CLL) is a lymphoproliferative disease with significant variation in disease progression, response to therapy, and survival outcome. Deletions of 17p or mutations of TP53 have been identified as one of the poorest prognostic factors, being predictive of short time for disease progression, lack of response to therapy, short response duration, and short overall survival. The treatment of patients with CLL has improved significantly with the development of chemoimmunotherapy, but this benefit was not pronounced in patients with 17p deletion. We compare various treatment strategies used in these patients, including FCR-like chemoimmunotherapy, alemtuzumab, other antibody combinations, or novel targeted therapies with promising results. Allogeneic stem cell transplantation offers the possibility for long-term disease control in these patients and should be considered early in younger, transplant-eligible patients. The current state of therapy is far from optimal and resources should be applied to studying therapeutic options for patients who have CLL with loss of p53 function.

Fluorescencein situHybridization Detection of Cytogenetic Abnormalities in B-cell Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma

Routine cytogenetic analysis of B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (B-CLL/SLL) frequently fails to identify an abnormal clone due to the low rate of spontaneous mitoses and poor response to mitogen stimulation. Recent studies utilizing interphase fluorescence in situ hybridization (FISH) suggest that prognostically significant chromosomal abnormalities occur more frequently in B-CLL/SLL than has been previously recognized. The purpose of this study was to compare the chromosomal abnormalities detected by karyotyping and FISH in cases of B-CLL/SLL, and to correlate these with clinical features and survival. Seventy-two cases were studied for chromosome 3, 12 or 18 aneuploidy, and for rearrangements involving 11q13, 11q23, 13q14, 14q32 and 17p13. The median age of the patients was 54 years (range, 30-87 years). Clinical staging of B-CLL patients showed that 70% of the patients were Rai stage 0, 1, or 2, and 30% stage 3 or 4. Karyotyping identified chromosomal abnormalities in 31% of the cases, whereas FISH studies were abnormal in 72% of cases including 64% of the cases with normal karyotypes. The most common abnormalities were deletion 13q14 (46%), trisomy 12 (21%), and 14q32 rearrangements (21%). At diagnosis, patients with trisomy 12 were more likely to have a high LDH (P = 0.04), but no other significant differences in the clinical or laboratory features, Rai stage, or survival were found among patients with normal cytogenetics vs. those with chromosomal abnormalities. Univariate analysis showed that B-symptoms (P = 0.044), anemia (P = 0.0006), absolute lymphocytosis > or = 30,000/mm3 (P = 0.029), and Rai stage 3 or 4 (P = 0.0038) at initial presentation were associated with an increased risk of death, but only Rai stage 3 or 4 (P = 0.0038) was significant in multivariate analysis. Interphase FISH studies improve the cytogenetic diagnosis when performed in conjunction with karyotyping in B-CLL/SLL, but the prognostic relevance of various abnormalities could not be confirmed in this study.

Chromosomal translocations are associated with poor prognosis in chronic lymphocytic leukemia

In chronic lymphocytic leukemia (CLL), chromosomes usually evade detailed cytogenetic analyses because cells poorly respond to the traditionally used set of mitogens. We applied novel technologies, such as stimulation of CLL cells either with CD40 ligand or with a combination of CpG-oligodeoxynucleotides and IL-2, to increase the frequency of metaphase spreads for detailed chromosome analysis in 96 patients with CLL. This approach revealed that translocations occurred in 33 of 96 (34%) of our patients with CLL. The presence of translocations defined a new prognostic subgroup because these patients have significantly shorter median treatment-free survival (24 months vs 106 months; P < .001) and significantly inferior overall survival (OS; median, 94 months) than patients without translocations (346 months; P < .001). In multivariate analysis-including Binet stage, complex karyotype, CD38 expression, and 17p deletions-translocation proved to be the prognostic marker with the highest impact for an unfavorable clinical outcome (P < .001). In summary, we identified a new subgroup of patients with CLL defined by chromosomal trans-locations and poor prognosis. Our data may facilitate the identification of molecular events crucial for transforming activity in this disease and should have implications for risk-adapted clinical management of patients with CLL.

CD40L stimulation enhances the ability of conventional metaphase cytogenetics to detect chromosome aberrations in B-cell chronic lymphocytic leukaemia cells

Conventional metaphase cytogenetics underestimates the frequency of specific chromosome aberrations in B-cell chronic lymphocytic leukaemia (B-CLL) as a result of the very low proliferative activity of these cells in vitro. New molecular approaches, such as fluorescence in situ hybridization (FISH) or comparative genomic hybridization (CGH), may circumvent this problem, at least in part, but these techniques are either strongly dependent on the knowledge of candidate regions or detect only unbalanced aberrations. In the present study, we analysed 27 B-CLL peripheral blood samples by metaphase cytogenetics after CD40 ligand (CD40L)-induced cell cycle stimulation. In comparison with the simultaneous use of B-cell mitogens such as 12-O-tetradecanoylphorbol-13-acetate (TPA), lipopolysaccharide (LPS) and pokeweed mitogen (PWM), CD40L stimulation of B-CLL cells induced a threefold increase in metaphases amenable to analysis by conventional cytogenetics. The analysis of these metaphases confirmed all genetic abnormalities detected by FISH. Moreover, CD40L-enhanced cytogenetics revealed complex karyotypic aberrations in 11 out of 27 patients (41%). In one case, a balanced translocation t(11;16)(p15;p13.1), so far unreported in B-CLL, was detected. Taken together, the results of our study show the potential of CD40L-enhanced metaphase cytogenetics to detect more and new chromosome aberrations in B-CLL.

Genetics of chronic lymphocytic leukemia: genomic aberrations and V(H) gene mutation status in pathogenesis and clinical course

The genetic characterization of chronic lymphocytic leukemia (CLL) has made significant progress over the past few years. While conventional cytogenetic analyses only detected chromosome aberrations in 40-50% of cases, new molecular cytogenetic methods, such as fluorescence in situ hybridization (FISH), have greatly enhanced our ability to detect chromosomal abnormalities in CLL. Today, genomic aberrations are detected in over 80% of CLL cases. Genes potentially involved in the pathogenesis were identified with ATM in a subset of cases with 11q deletion and p53 in cases with 17p13 deletion. For the most frequent aberration, the deletion 13q14, candidate genes have been isolated. Genetic subgroups with distinct clinical features have been identified. 11q deletion is associated with marked lymphadenopathy and rapid disease progression. 17p deletion predicts for treatment failure with alkylating agents, as well as fludarabine and short survival times. In multivariate analysis 11q and 17p deletions provided independent prognostic information. Recently, another important issue of genetic risk classification in CLL was identified with the mutation status of the immunoglobulin variable heavy chain genes (V(H)). CLL cases with unmutated V(H) show more rapid disease progression and shorter survival times. Whether CD38 expression can serve as a surrogate marker for V(H) mutation status is currently discussed controversially. V(H) mutation status and genomic abnormalities, such as 17p and 11q deletion, have recently been shown to be related to each other, but were of independent prognostic information in multivariate analysis. Moreover, genomic aberrations and V(H) mutation status appear to give prognostic information irrespective of the clinical stage and may therefore allow a risk assessment for individual patients early in the course of their disease.

Molecular abnormalities in B-cell chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia is the commonest adult leukaemia, however the pathogenesis is largely unknown. Since the 1980s specific chromosomal abnormalities have been identified, of which the commonest are deletions of chromosomes 6q, 11q23, 13q14 and 17q13 and trisomy 12. The search for the responsible oncogenes at these sites has proved to be extremely frustrating. There are many oncogenes at 11q23 but the exact gene(s) responsible have yet to be identified. Germline abnormalities of the ATM gene occur in about 18% of patients compared to a normal population carriage of 0.5% but not all studies agree that ATM is the gene responsible. Unfortunately, despite the identification of various minimally deleted regions and the full sequencing of 13q14 no oncogenes have been identified. All original studies suggested the presence of a autosomally recessive tumour suppressor gene at this site but more recent studies suggest this may not be the case and the pathogenesis is more complex than first thought. Similarly, no genes have been identified at 6q or on chromosome 12. We know that the p53 tumour suppressor gene at 17p13 is an important prognostic indicator but it occurs in a minority of patients (about 15%), usually in patients with advanced disease, and therefore probably is not of aetiological importance.

Altered expression of nuclear non-histone protein (p44/46) in different stages of B-chronic lymphocytic leukemia

Our previous data have shown some differences in electrophoretic characteristics of proteins from cellular fractions (nuclear, mitochondrial, microsomal and cytosolic) isolated from peripheral blood mononuclear cells of B-cell chronic lymphocytic leukemia (B-CLL), acute lymphoblastic leukemia (ALL) patients and healthy donors. The main differences were found in electrophoretic patterns of nuclear proteins from normal and leukemia cells, especially in the nuclear mass regions of 36-52, 58-85, and 120-180 kDa. Electrophoretically-specific nuclear non-histone protein in the molecular mass zone 44/46 kDa of cells obtained from the peripheral blood of a B-CLL patient was used to produce rabbit polyclonal antiserum. SDS-polyacrylamide gel electrophoresis as well as immunological techniques (Western blot and immunocytochemistry) indicate that the nuclear protein with a molecular mass of 44/46 kDa is specifically expressed in mononuclear cells from B-CLL patients. The expression of this particular nuclear protein seems to correlate with the progression of the leukemia.

11q deletions in hematological malignancies

Structural aberrations involving 11q are among the most common aberrations in a number of hematological malignancies. Most of the aberrations, such as translocations and deletions, often harbor a breakpoint at 11q23, which suggests that this region might contain a tumor suppressor gene important for the genesis of lymphoproliferative disorders. Interestingly, deletions are concentrated only in some subtypes of hematological malignancies, where they are detected at a relatively high frequency. In B-cell chronic lymphocytic leukemia (B-CLL), deletions have been detected in 20-30% of the cases, whereas almost half of the mantle cell lymphomas (MCL) show deletion at 11q23 in fluorescence in situ hybridization analysis. In T-cell prolymphocytic leukemia (T-PLL), deletions involving the region 11q23.3-23.1 have also been detected to be frequent. In B-cell chronic lymphocytic leukemia, 11q deletion is associated with more rapid disease progression and poor survival in a younger subgroup of patients. The putative tumor suppressor genes have remained unrevealed until recently, when the ATM gene was found to carry mutations in cases with deletion in B-CLL, MCL and T-PLL. These data suggest that 11q deletions and dysfunction of the ATM gene might have significance in the tumorigenesis of certain subsets of hematological malignancies. Importance of 11q deletion as a diagnostic marker needs to be further studied in a larger series of patients. Another issue that remains to be investigated is the involvement of other target genes in the deletion.

Genetic features of B-cell chronic lymphocytic leukemia

The genetic features of B-cell chronic lymphocytic leukemia (CLL) are currently being reassessed by molecular cytogenetic techniques such as fluorescence in situ hybridization (FISH). Conventional cytogenetic studies by chromosome banding are difficult in CLL mainly because of the low in vitro mitotic activity of the tumor cells, which leads to poor quantity and quality of metaphase spreads. Molecular genetic analyses are limited because candidate genes are known for only a few chromosomal aberrations that are observed in CLL. FISH was found to be a powerful tool for the genetic analysis of CLL as it overcomes both the low mitotic activity of the CLL cells and the lack of suitable candidate genes for analysis. Using FISH, the detection of chromosomal aberrations can be performed at the single cell level in both dividing and non-dividing cells, thus circumventing the need of metaphase preparations from tumor cells. Probes for the detection of trisomies, deletions and translocation breakpoints can be applied to the regions of interest with the growing number of clones available from genome-wide libraries. Using the interphase cytogenetic FISH approach with a disease specific set of probes, chromosome aberrations can be found in more than 80% of CLL cases. The most frequently observed abnormalities are losses of chromosomal material, with deletions in band 13q14 being the most common, followed by deletions in 11q22-q23, deletions in 17p13 and deletions in 6q21. The most common gains of chromosomal material are trisomies 12q, 8q and 3q. Translocation breakpoints, in particular involving the immunoglobulin heavy chain locus at 14q32, which are frequently observed in other types of non-Hodgkin's lymphoma, are rare events in CLL. Genes affected by common chromosome aberrations in CLL appear to be p53 in cases with 17p deletion and ataxia telangiectasia mutated (ATM), which is mutated in a subset of cases with 11q22-q23 aberrations. However, for the other frequently affected genomic regions, the search for candidate genes is ongoing. In parallel, the accurate evaluation of the incidence of chromosome aberrations in CLL by FISH allows the correlation of genetic abnormalities with clinical disease manifestations and outcome. In particular, 17p abnormalities and deletions in 11q22-q23 have already been shown to be among the most important independent prognostic factors identifying subgroups of patients with rapid disease progression and short survival. In addition, deletion 17p has been associated with resistance to treatment with purine analogs. Therefore, genetic abnormalities may allow a risk assessment for individual patients at the time of diagnosis, thus giving the opportunity for a risk-adapted management.

Lymphocyte-specific protein 1: a specific marker of human leucocytes

While both murine and human homologues of the LSP1 gene (lymphocyte-specific gene 1) and its protein products have been identified, studies on human LSP1 have been limited. The present report describes a detailed immunocytochemical study of the distribution and localization of human LSP1 in both normal and neoplastic cells and tissues. The specificity of the monoclonal anti-LSP1 reagent was confirmed by expression cloning and transfection studies. The intracellular 60 000 MW LSP1 protein was found to be present in peripheral blood B cells, monocytes and granulocytes but absent in a subpopulation of circulating T cells (10-15% of CD3-positive T cells). The presence of LSP1 protein in medullary thymocytes, but only in scattered cortical thymocytes, provided additional evidence for heterogeneity of expression in T cells. Novel observations also included the presence of LSP1 in plasma cells, dendritic cells and Langerhans' cells. The leucocyte-restricted distribution of LSP1 protein means that it may play an important role in haematopathology. LSP1 protein was detected in a wide range of leukaemias and lymphomas, particularly of B-cell origin, and in tumour cells in classical Hodgkin's disease. Of interest was the indication of a reciprocal relationship in the expression of LSP1 and ALK (anaplastic lymphoma kinase) proteins in patients with anaplastic large cell lymphoma. As the anti-LSP1 reagent used in the present study recognizes a formalin-resistant epitope it should be of considerable value in the diagnosis of routinely fixed material.

Trisomy 12 in chronic lymphocytic leukemia--geographical variation

Incidence of trisomy 12 was studied in 60 cases of chronic lymphocytic leukemia (CLL) with chromosome 12 specific alpha-satellite DNA probe by fluorescence in situ hybridization (FISH). Trisomy 12 was observed in 37 (61.8%) patients. Cells with trisomy 12 were detected in a varying proportion, ranging from > 2% to 86%. Patients with trisomy 12 were predominantly observed with total white blood cell (WBC) count > 80 x 10(9) l(-1) (P < 0.001). In addition, the percentage of trisomy 12 positive lymphocytes correlated with the high WBC counts. Trisomy 12 was observed equally in typical and atypical CLL. 90% of our patients were in the intermediate and high risk groups. It was seen that there was significantly higher percentage of trisomy 12 positive lymphocytes ( > 10%) in the high risk groups (P < 0.05). A higher incidence of FMC7 positivity in atypical CLL was seen in our study. However, there was no significant relationship found between trisomy 12 positivity and expression of either FMC7 or CD23 in our cases. It appears that the CLL that we see at our centre is at a different phase of evolution and perhaps biologically different compared to the CLL seen in the West.

Therapeutic management of hematological malignancies in elderly patients. Biological and clinical considerations. Part III: The chronic leukemias and myelofibrosis

The different therapeutic options available for the treatment of chronic leukemias and myelofibrosis are discussed. In reference to chronic myeloid leukemia (CML), the choice of the most appropriate treatment must take into account not only the clinical condition but also the age of the patient. While subjects under 50 might benefit from the options offered by alpha-interferon, bone marrow and peripheral stem cell transplant, in older age groups treatment of the chronic phase must still rely on standard treatment. Chronic lymphocytic leukemia (CLL) and its variants is a disease of mostly middle and late life, with a variable clinical course. Patients show wide differences in morbidity and mortality. Many features have been shown to influence the prognosis, and the most important ones are incorporated into the staging systems currently in use. The results obtained from the study of large trials support the concept that treatment of patients with stable stage A CLL should be postponed until progression of disease. Treatment relies principally on alkylating agents, corticosteroids and radiation therapy; the new nucleoside analogues, such as fludarabine and 2-chlorodeoxyadenosine, have recently acquired established value in improving overall survival. With regard to myelofibrosis, the histological and biological features that influence the natural course of the disease are described, as well as the choice of the most appropriate treatment, which ranges from the use of alkylating agents and androgens, to splenectomy and splenic irradiation.

Chronic lymphocytic leukaemia: the nature of the leukaemic cell

Far from being the boring, inactive, inert lymphocyte that haematologists of old perceived it to be, the chronic lymphocytic leukaemia (CLL) cell has set us many complex problems. The cell is apparently stuck in G0 in cell cycle, yet expresses many activation markers. The cells apparently manufacture many cytokines and respond in vitro to even more, yet cells entering even G1 are few. The cell surface marker profile is unique. There is apparently no normal equivalent of the CLL cell. In part, this may be because the cell is malignant; malignant cells often express aberrant markers. Consistent chromosomal abnormalities are emerging but we have no idea how these abnormalities translate into molecular mistakes that dictate the peculiar nature of the cell. CLL cells carry a characteristics set of adhesion molecules, but we cannot read their homing and recycling instructions. The outstanding irregularities of the CLL cell are its CD5 positivity and its sparse surface immunoglobulin. This ought to translate as an anergic B1 cell, perhaps programmed for autoimmunity. If the tumour cell were responsible for the patient's production of immunoglobulin or secretion of autoantibodies, then a pattern might have emerged. Alas, these are the product of the normal B cells. How the CLL cell induces these complications is unknown. Thus, despite the information contained in this review, the CLL cell remains a puzzle.

11q Deletions Identify a New Subset of B-Cell Chronic Lymphocytic Leukemia Characterized by Extensive Nodal Involvement and Inferior Prognosis

Deletions of the long arm of chromosome 11 (11q) are one of the most frequent structural chromosome aberrations in various types of lymphoproliferative disorders. However, in most conventional chromosome banding studies of B-cell chronic lymphocytic leukemia (B-CLL), 11q deletions were not identified as a frequent aberration. The objective of this study was to analyze the frequency and clinical impact of 11q deletions in B-CLL by interphase cytogenetics using fluorescence in situ hybridization (FISH). Mononuclear cells from 214 patients with B-CLL were studied by FISH using the yeast artificial chromosome (YAC) clone 755b11 from chromosome region 11q22.3-q23.1; we previously showed that this clone was contained within a 2- to 3-Mb sized segment of 11q commonly deleted in lymphoproliferative disorders. Forty-three of the 214 (20%) tumors exhibited 11q deletions; 11q deletions were the second most frequent chromosome aberration following 13q14 (RB1 and/or D13S25) deletions (45%); they were more frequent than trisomy 12 (15%) or deletion of 17p (TP53 gene) (10%). Patients with 11q deletions were younger (P = .01) and had more advanced clinical stages (P = .01). 11q deletions were associated with extensive peripheral, abdominal, and mediastinal lymphadenopathy (P &lt; .001). Patients with 11q deletions had a more rapid disease progression as shown by a shorter treatment-free interval (9 months v 43 months; P &lt; .001). The prognostic effect of 11q deletion on survival strongly depended on the age: in patients less than 55 years old, the median survival time was significantly shorter in the deletion group (64 months v 209 months; P &lt; .001), whereas in patients ≥ 55 years old there was no significant difference (94 months v 111 months; P = .82). 11q deletions identify a new clinical subset of B-CLL characterized by extensive lymph node involvement. In younger B-CLL patients, this aberration is an important predictor of survival.

Interphase cytogenetics in chronic lymphocytic leukemia

The incidence of trisomy 12 and 13q12-q14 abnormalities in patients with chronic lymphocytic leukemia (CLL) was determined by conventional cytogenetics and interphase fluorescence in situ hybridization (FISH). In the analysis of 580 consecutive patients, trisomy 12 was detected by conventional cytogenetics in 39 cases (9%) and 117 cases (20%) by FISH. Trisomy 12 was shown to be associated with advanced clinical stage, atypical morphology, and higher proliferative activity. Combined immunophenotyping and FISH showed that trisomy 12 was present only in a proportion of the clonal B-cells. These data suggest that trisomy 12 is a secondary event associated with features of disease progression. Sequential FISH showed clonal progression of the trisomic clone over time. Three hundred patients also were investigated for 13q deletions using FISH analysis of the RB1 locus (13q14). Monoallelic RB1 deletion was seen in 104 (34%) of cases. One case had a homozygous deletion in 90% of the cells. Dual-color FISH detected the presence of trisomy 12 and RB1 in 17 (5%) cases. DNA probes for 13q12.3 (BRCA2) and 13q14 (RB1 and DBM locus) were used in 35 cases. Twenty-eight (80%) cases showed deletion of a 1Mb 13q12.3 encompassing the BRCA2 locus, whereas 22/35 (63%) were deleted at 13q14. Our data suggest that abnormalities of 13q are more frequent than trisomy 12 in CLL and provide evidence for the presence of a new candidate gene at 13q12.3 that may be involved in the pathogenesis of CLL.

Genetic abnormalities in chronic lymphocytic leukemia and their clinical and prognostic implications

Clonal chromosome abnormalities can be detected in approximately 50% of patients with chronic lymphocytic leukemia (CLL). The most common changes are trisomy 12, followed by structural abnormalities of 13q, 11q, 6q, and 14q. By fluorescence in situ hybridization (FISH), these aberrations can be demonstrated even in cases with insufficient mitotic yield or a normal karyotype. The biologic consequences of trisomy 12 are unknown, but a gene dosage effect is suspected and studies on partial trisomy 12 indicate that the region 12q13 to 12q22 might be of particular pathogenetic importance. Trisomy 12 is strongly associated with atypical lymphocyte morphology and seems to be a secondary event in leukemogenesis, as shown by combined immunophenotyping and interphase FISH. Structural abnormalities of 13q frequently involve hetero- and homozygous deletions of a region in 13q14, distal to the retinoblastoma gene, which may be the site of a tumor suppressor gene. In contrast to a normal karyotype or structural changes of 13q, complex karyotypic abnormalities, high percentage of abnormal metaphases, trisomy 12 and structural changes involving the P53 tumor suppressor gene on 17p13 are adverse prognostic indicators. Cytogenetic and molecular findings provide important diagnostic, clinical, and prognostic information which can contribute to treatment decisions and follow-up of CLL patients.

Genes and chromosomes in chronic B-cell leukemia

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence in situ hybridization (FISH) and molecular techniques reveal an even higher incidence. Trisomy 12 and deletions or translocation of chromosome 13q14 are the most common abnormalities, but in neither case has the gene or genes involved in the abnormalities been identified. Combined FISH and immunophenotyping studies suggest that both abnormalities are secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormalities have not been identified. Involvement of the BCL1, BCL2, and BCL3 genes has been reported, but the numbers are low and the cases tend to be atypical. Trisomy 12 in association with complex karyotypic abnormalities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanced disease. Ten to 15% of patients have mutations of p53 which is associated with advanced disease, resistance to treatment, and poor survival.

BCL3 rearrangement and t(14;19)(q32;q13) in lymphoproliferative disorders

Translocation t(14;19)(q32;q13) is a rare but recurrent abnormality in chronic lymphocytic leukemia and small cell lymphoma. It has been associated with rearrangements of the BCL3 gene, which is located at the breakpoint on chromosome 19 and is juxtaposed to the immunoglobulin heavy chain locus on chromosome 14 as a result of the translocation. This results in transcriptional up-regulation of the BCL3 gene, which encodes a transcription coactivator, an I-kappa B protein, probably contributing to disease progression. We found, among 4,487 cytogenetic analyses of lymphoproliferative disorders, six cases with a t(14;19)(q32;q13), five of which showed the classical t(14;19)(q32;q13) and one of which showed a three-way translocation t(7;19;14)(q21;q13;q32). The 14;19 translocation never occurred as a single abnormality; additional aberrations included trisomy 12 and several structural abnormalities. The cytogenetic examination was supplemented by molecular analysis using available probes for the BCL3 locus (p alpha 1.4P and p alpha 5B) in 1,150 of the 4,487 patients. Rearrangements of BCL3 could be detected in five cases, all of which had the classical t(14;19). In the case with t(7;19;14), the suspected BCL3 involvement could only be confirmed using long-range restriction mapping, indicating that, with the usually available BCL3 probes, rearrangements of this locus may be missed.

Clinical, biological, and immunophenotypical characteristics of B-cell chronic lymphocytic leukemia with trisomy 12 by fluorescence in situ hybridization

The clinical, biological, and immunophenotypical characteristics of B-cell chronic lymphocytic leukemia (B-CLL) patients with trisomy 12 detected by fluorescence in situ hybridization (FISH) using a chromosome 12 alpha-centromeric probe (D12Z3) were analyzed in the present study. From a total of 104 consecutive B-CLL patients, 21 (20%) displayed trisomy 12, the percentage of trisomic cells ranging from 13% to 76%. From the clinico-biological point of view, patients with trisomy 12 were associated with atypical CLL morphology (43% vs 10%, P = 0.04) and BM diffuse pattern (75% vs. 25%, P = 0.02) together with increased WBC counts (141 +/- 220 vs. 58 +/- 67 x 10(9)/L, P = 0.04). In contrast, no association was detected between the presence of trisomy 12 and other disease characteristics such as age, sex, clinical stage, hepatomegaly, lymphadenopathies, haemoglobin levels and platelet counts, and the cell cycle distribution of PB leukocytes in both groups of patients. Trisomy 12 patients had a significantly higher expression of the FMC7 antigen both in percentage (34 +/- 34% vs. 13 +/- 20%, P = 0.02) and absolute numbers (29 +/- 62 vs. 7 +/- 17 x 10(9)/L, P = 0.007). No major differences were found regarding the expression of mouse rosettes, CD19+, and CD19+/CD5+ lymphocytes. Upon analyzing the correlations between the disease characteristics of trisomy 12 cases, significant associations were found between the percentage of trisomic cells and both the WBC count (r = 0.52, P = 0.02) and the PB lymphocyte count (r = 0.60, P = 0.007).(ABSTRACT TRUNCATED AT 250 WORDS)

Molecular cytogenetic analysis of RB-1 deletions in chronic B-cell leukemias

Deletions or translocations of 13q, most commonly involving band 13q14, belong to the most frequent structural chromosome abnormalities in B-cell chronic lymphocytic leukemia (B-CLL). In a combined metaphase and interphase cytogenetic study using conventional G-banding analysis and fluorescence in situ hybridization (ISH) we previously analysed the retinoblastoma susceptibility gene (RB-1) and its chromosomal locus 13q14 in 35 patients with chronic B-cell leukemias. We report here on the interphase cytogenetic analysis of 109 cases with chronic B-cell leukemias [B-CLL = 90; B-prolymphocytic leukemia (B-PLL) = 6, hairy cell leukemia (HCL) = 13]; a subset of 49 patients (B-CLL = 45; B-PLL = 4) was studied by conventional G-banding analysis. By G-banding, 5/45 (11%) patients with B-CLL had deletions or translocations affecting band 13q14; in contrast, ISH to interphase cells showed RB-1 deletion in 19/90 (21%) patients with B-CLL. No 13q14 abnormalities or RB-1 deletion were detected in patients with B-PLL and HCL. Our data confirm the high frequency of RB-1 deletions in B-CLL and further emphasize the possible pathogenetic role of this genomic region.

Isochromosomes in neoplasia

In order to ascertain the frequency and distribution of isochromosomes in neoplasia, we surveyed the cytogenetic data from 20,007 tumors with clonal chromosome aberrations reported in the literature. Tumor types for which at least 50 cases with acquired aberrations and 10 cases with isochromosomes had been reported were selected, yielding a total of 18,160 neoplasms. Of these, 1,792 cases (9.9%) displayed a total of 2,014 isochromosomes. The 9 most common isochromosomes (detected in at least 50 cases) were, in decreasing order of frequency, i(17q), i(8q), i(1q), i(12p), i(6p), i(7q), i(9q), i(5p), and i(21q). The frequency of isochromosomes varied among the different tumor types, with the highest incidence in germ cell neoplasms (60%) and the lowest in chronic myeloproliferative disorders (2.3%). Also, the spectrum of isochromosomes differed among the neoplasms. The most common isochromosomes in the different tumor types were i(11q), i(17q), and i(21q) in acute myeloid leukemia; i(9q), i(17q), and i(22q) in chronic myeloid leukemia; i(17q) in chronic myeloproliferative disorders; i(X)(q13), i(17q), and i(21q) in myelodysplastic syndromes; i(7q), i(9q), and i(17q) in acute lymphoblastic leukemia; i(1q), i(7q), i(8q), and i(17q) in chronic lymphoproliferative disorders; i(1q), i(6p), i(9p), i(17q), and i(21q) in Hodgkin's disease; i(1q), i(6p), and i(17q) in non-Hodgkin's lymphoma; i(1q), i(8q), and i(17q) in adenocarcinoma; i(1q), i(3q), i(5p), and i(8q) in squamous cell carcinoma; i(5p), i(8q), and i(11q) in transitional cell carcinoma; i(1q), i(7q), and i(17q) in Wilms' tumor; i(1q), i(12p), and i(17q) in germ cell neoplasms; i(1p), i(1q), i(6p), and i(17q) in sarcoma; i(5p), i(6p), i(7p), and i(21q) in mesothelioma; i(1q), i(6p), and i(17q) in malignant neurogenic neoplasms; i(1q), i(6p), and i(17q) in retinoblastoma; and i(1q), i(6p), and i(8q) in malignant melanoma.

Trisomy 12 is uncommon in typical chronic lymphocytic leukaemias

The incidence of trisomy 12 was studied by conventional chromosome analysis in 111 patients referred as B-cell chronic lymphocytic leukaemia (B-CLL). Fluorescent in situ hybridization (FISH) was also applied in 34 of those patients with either a normal karyotype or no analysable mitoses. By karyotyping, trisomy 12 was present in 11.7% (13/111), whereas additional FISH increased the incidence to 14.4% (16/111). When subdividing our cases in either typical CLL (n = 90), fulfilling the FAB classification criteria, or atypical CLL (n = 21), with one or more variations from those criteria, the incidence of +12 by metaphase analysis was 3% and 48%, respectively. Additional FISH increased the incidence to 4% and 57%. The most common aberration in atypical CLL was FMC7 positivity (n = 11), followed by CD5 negativity (n = 8), strong surface immunoglobulin staining (n = 7) and atypical morphology (n = 6). Trisomy 12 could only be demonstrated in a small proportion of neoplastic cells in all positive cases. By FISH and/or karyotyping, all available samples at diagnosis of the disease were positive.

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.

Chronic lymphocytic leukaemia: prognostic factors and natural history

In the past 20 years, important progress has been made in the understanding of the natural history and prognosis of chronic lymphocytic leukaemia (CLL). Based on the notion that the clinical manifestations of CLL are due primarily to the progressive accumulation of lymphocytes over time, several prognostic factors have been identified. The prognostic value of parameters reflecting tumour burden (i.e. lymphadenopathy, splenomegaly, anaemia and/or thrombocytopenia due to bone marrow failure), first identified empirically, has been confirmed in multivariate analyses of large series of patients. Furthermore, clinical staging systems that group the most relevant of these factors have also been developed. Patients in early stage (Binet A; Rai 0) have a long survival which, in some cases, may match that of the general population. In contrast, patients with advanced stage (Binet C; Rai III or IV) have a median survival < 2 years. The major limitation of staging systems is that they do not give information about the likelihood of progression for patients in early stage. Nevertheless, haemoglobin level, blood lymphocyte count, lymphocyte doubling time and bone marrow infiltration pattern are useful to identify subsets of patients in early stage with different progression and survival rates, with the 'smouldering' form of the disease being identified fairly accurately. With all these advances, therapy in CLL can now be indicated on a more rational basis. However, further biological insight is needed to elucidate the mechanism accounting for the different forms of the disease.

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.

Japanese B cell chronic lymphocytic leukaemia: a cytogenetic and molecular biological study

Clinical, cytogenetic, and molecular genetic studies were performed to clarify the pathophysiology of Japanese B cell chronic lymphocytic leukaemia (B-CLL), since the incidence of B-CLL in Japan is significantly lower than in western countries. The clinical and laboratory features of 55 Japanese patients with B-CLL in this study did not differ from those of Americans or Europeans with B-CLL. In the chromosome analyses, suitable metaphases with good band quality were obtained from 48 patients (87.2%), of whom 22 patients (45.8%) showed clonal chromosome aberrations and 14 (29.2%) had non-clonal aberrations. Trisomy 12 and abnormalities of 14q and 13q were found in four (18.2%), two (9.1%) and six patients (27.2%), respectively. There were no particular chromosome abnormalities or specific breakpoints in Japanese B-CLL. However, complex karyotype was found in higher incidence than in western countries. In the Southern blot analyses, rearranged band patterns were observed in the major breakpoint region (mbr) of the bcl-2 gene in one case, in the 5'-breakpoint region (5'-bcl-2) in two, and bcl-3 in one. Of the two patients with 5'-bcl-2 rearrangements, one had a normal karyotype and the other had t(2;18)(p12;q21). The incidence of rearrangements of the bcl-1, bcl-2 and bcl-3 genes in Japanese B-CLL was similar to that in western countries. These findings suggest that the biological characteristics of B-CLL in Japan are almost the same as those in western countries, although the incidence of B-CLL in Japan is quite different; this may be related to racial differences, which seem to be an important factor in the development of B-CLL.

A polymerase chain reaction-based method for the detection of trisomy 12 in B chronic lymphocytic leukaemia

We report a polymerase chain reaction (PCR)-based method for detection of clonal trisomy 12 cell populations in B cell chronic lymphocytic leukaemia which is particularly applicable to retrospective analysis or archival material. The method utilizes three restriction enzyme site polymorphisms linked to the KRAS2 locus on chromosome 12 to monitor allele imbalance resulting from duplication of this chromosome. 21/24 unselected chronic lymphocytic leukaemia cases (88%) were informative for at least one polymorphism and of these, eight (33% of total cases) displayed allelic imbalance consistent with trisomy 12.

Isochromosome 1q in acute monocytic leukemia: a new nonrandom association

We report a case of de novo acute monocytic leukemia in a 25-year-old man in whom the sole clonal cytogenetic abnormality was an additional isochromosome 1q. Cytogenetic polymorphisms indicate that, in addition to the formation of the isochromosome, a duplication of the remaining normal chromosome 1 had taken place. Other reported cases suggest an association between acute monocytic leukemia and i(1q).

Trisomy 12 in Epstein-Barr virus-transformed lymphoblastoid cell lines of normal individuals and patients with nonhematologic malignancies

Karyotypes of 36 lymphoblastoid cell lines established by Epstein-Barr virus (EBV) transformation of peripheral blood lymphocytes (PBL) of eight normal individuals and 28 patients with various nonhematologic malignancies were analyzed. In seven lines (19.4%), cells with trisomy 12 were noted, with clonality in two of these lines. In two of 11 metaphases with such trisomy, chromosome 12 was involved in structural rearrangements [t(8;12)(q12;p12) and t(12;12)(q11;q24)]. No cells with trisomy 12 were observed in phytohemagglutinin (PHA)-stimulated PBL cultures of these individuals. In 250 individuals (normal and with nonhematologic malignancies) examined in our laboratory in the last 5 years, extra copies of chromosome 12 in PHA-stimulated PBL cultures were observed in only five of 23,216 cells (0.02%). There were no cases of clonality in these samples. The frequency of an extra chromosome 12 was comparable to that of the other chromosomes except 21 and X, whose frequency of occurrence was 0.08% and 0.09%, respectively. These findings should be considered random events in PHA-stimulated PBL. On the contrary, in lymphoblastoid cell lines established by EBV transformation, trisomy of chromosome 12 was the most frequent numerical abnormality. It was observed in 64.7% of all cases with chromosome gains and therefore could not be considered a random occurrence. The specificity of this phenomenon for EBV transformation is supported by the results of cytogenetic analysis of eight lymphoblastoid cell lines established by an alternative procedure in our laboratory [1]. In 400 cells analyzed not a single cell with trisomy 12 was observed. We suggest that EBV transformation might either randomly induce formation of such cells in immortalized B-cell populations or show potentially blastomogenic cells or proneness to their formation in certain individuals who could be predisposed to develop lymphoproliferative diseases, especially chronic lymphocytic leukemia (CLL) in which trisomy of chromosome 12 is the most common alteration.

Frequent clonal abnormalities of chromosome band 13q14 in B-cell chronic lymphocytic leukemia: multiple clones, subclones, and nonclonal alterations in 82 midwestern patients

We performed cytogenetic analyses of peripheral blood lymphocytes from 82 Midwestern B-cell chronic lymphocytic leukemia (B-CLL) patients. The cells were cultured with mitogens for 3-4 days. At least 15 metaphase cells were analyzed in 79 (96%) cases. Fifty (63%) of the 79 patients had clonal chromosomal alterations. Structural modifications of the long arm of chromosome 13 at or near band 13q14 were the most frequent abnormalities, identified in 23 (46%) of the patients with clonal abnormalities. In several patients, the abnormality involving band 13q14 was the sole chromosomal alteration. There was a high incidence of complex karyotypes. Nine patients had multiple subclones that appeared to result from clonal evolution; seven patients had cytogenetically unrelated clones; three patients had both subclones and cytogenetically unrelated clones. Nonclonal abnormalities were also prominent. Our study confirms the high incidence of clonal abnormalities involving chromosome arm 13q and documents the clustering of abnormalities at band 13q14 in B-CLL. The evidence for clonal evolution and the presence of multiple unrelated clones in these patients suggest that B-CLL may not be a karyotypically stable disease.

Non-radioactive in situ hybridization for the detection and monitoring of trisomy 12 in B-cell chronic lymphocytic leukaemia

Non-radioactive in situ hybridization (NISH) with a chromosome 12-specific alpha satellite probe was performed on 20 patients with chronic lymphocytic leukaemia (CLL) with normal karyotype (15 cases) or with inadequate mitotic yield (5 cases) from mitogen-stimulated cultures. All patients had over 70% lymphocytes coexpressing the CD5/CD23 antigens. While less than 1% interphase nuclei showed three fluorescent spots in 16/20 patients, evidence of trisomy 12 in 15-25% interphase cells was detected in four patients. According to the FAB classification the diagnosis in these patients was typical B-CLL, stage III (Rai's staging system) in one case, CLL/PLL, stage II and III in two cases, PLL, stage III in one case. In order to confirm these results, NISH was repeated after 1 month in one patient and after 2 years in three patients. All patients had been treated with chemotherapy in the period between the two NISH experiments. In all cases a 1.8-3-fold increase of percentage of trisomic interphase cells was detected. These findings suggest that in B-CLL clones with trisomy 12 may have proliferative advantage over clonal B-lymphocyte without +12 and, possibly, that they may be more resistant to chemotherapy. We conclude that NISH is a sensitive technique allowing for the detection and monitoring of trisomy 12 in a fraction of B-CLL patients with normal karyotype or with no analysable mitoses despite employment of polyclonal B-cell mitogens.

A prospective study of the evolution of chronic lymphocytic leukaemia

The clinical course of chronic lymphocytic leukaemia (CLL) in 126 patients has been examined over the period 1961-88. The evolution of early stages, 0-I, to late stages, III-IV, occurred frequently without an orderly progression through the intermediate stages. The tumour load as judged by lymphadenopathy and splenomegaly was similar in stages II, III and IV. It would seem that stages 0-II represent a continuous spectrum of increasing tumour load, whereas stages III and IV with tumour load of equal magnitude and suppression of haemopoiesis are likely results of a change in biological behaviour of malignant lymphocytes. Stage II(S) characterised by splenomegaly and absence of lymphadenopathy seems a distinct entity with a unique clinical course. Further evolution of CLL in these patients was characterised by progressive splenomegaly, and as this became marked the clinical course was dominated by 'hypersplenism'. Splenectomy at this late stage led to rapid relief of symptoms, progressive increase of Hb and platelets to normal levels and to a quiescent phase of CLL for a considerable period. The tumour load in stage II(S) was of the same order of magnitude as in stages II, III and IV, yet the survival was similar to that in stage 0. Survival correlated with clinical stage and age at the time of diagnosis, but showed no relation to sex. The significance of these findings is further discussed.

A clinical update on chronic lymphocytic leukemia. I. Diagnosis and prognosis

B-cell chronic lymphocytic leukemia (B-CLL) is a relatively indolent hematologic malignant disease that, despite a good response to nonaggressive orally administered chemotherapy, currently remains incurable. The overall median duration of survival is more than 5 years, and the presence of anemia or thrombocytopenia adversely affects prognosis. B-CLL is readily diagnosed because of the characteristic and specific phenotypic expressions of the neoplastic cells. Clinical staging continues to be the best prognostic indicator in B-CLL. In addition, cytogenetic status, pattern of leukemic infiltration in the bone marrow, and lymphocyte doubling time are now considered to have additional prognostic value. In this article, the diagnostic evaluation of lymphocytosis is discussed, and an updated analysis on the prognostic determinants of B-CLL is provided. The second part of this clinical update, which reviews current chemotherapeutic modalities, will be published in the subsequent issue of this journal.

Isochromosome (6p) in Waldenstrom's macroglobulinemia

Cytogenetic data on two cases of previously treated Waldenstrom's macroglobulinemia (WM) are presented. An i(6p) was identified in 60 and 56% of bone marrow (BM) metaphases from each patient, respectively. In both cases, i(6p) occurred as part of a complex karyotype but was also observed as the sole abnormality in a proportion of metaphases. The literature on the cytogenetics of WM and the relevance of i(6p) is discussed.