Translocations involving the short arm of chromosome 17 in chronic B-lymphoid disorders: frequent occurrence of dicentric rearrangements and possible association with adverse outcome

Telomere and Centromere Staining Followed by M-FISH Improves Diagnosis of Chromosomal Instability and Its Clinical Utility

Dicentric chromosomes are a relevant marker of chromosomal instability. Their appearance is associated with telomere dysfunction, leading to cancer progression and a poor clinical outcome. Here, we present Telomere and Centromere staining followed by M-FISH (TC+M-FISH) for improved detection of telomere dysfunction and the identification of dicentric chromosomes in cancer patients and various genetic syndromes. Significant telomere length shortening and significantly higher frequencies of telomere loss and deletion were found in the peripheral lymphocytes of patients with cancer and genetic syndromes relative to similar age-matched healthy donors. We assessed our technique against conventional cytogenetics for the detection of dicentric chromosomes by subjecting metaphase preparations to both approaches. We identified dicentric chromosomes in 28/50 cancer patients and 21/44 genetic syndrome patients using our approach, but only 7/50 and 12/44, respectively, using standard cytogenetics. We ascribe this discrepancy to the identification of the unique configuration of dicentric chromosomes. We observed significantly higher frequencies of telomere loss and deletion in patients with dicentric chromosomes (p < 10⁻⁴). TC+M-FISH analysis is superior to classical cytogenetics for the detection of chromosomal instability. Our approach is a relatively simple but useful tool for documenting telomere dysfunction and chromosomal instability with the potential to become a standard additional diagnostic tool in medical genetics and the clinic.

Targeting sphingolipid metabolism as an approach for combination therapies in haematological malignancies

Conventional chemotherapy-based drug combinations have, until recently, been the backbone of most therapeutic strategies for cancer. In a time of emerging rationale drug development, targeted therapies are beginning to be added to traditional chemotherapeutics to synergistically enhance clinical responses. Of note, the importance of pro-apoptotic ceramide in mediating the anti-cancer effects of these therapies is becoming more apparent. Furthermore, reduced cellular ceramide in favour of pro-survival sphingolipids correlates with tumorigenesis and most importantly, drug resistance. Thus, agents that manipulate sphingolipid metabolism have been explored as potential anti-cancer agents and have recently demonstrated exciting potential to augment the efficacy of anti-cancer therapeutics. This review examines the biology underpinning these observations and the potential use of sphingolipid manipulating agents in the context of existing and emerging therapies for haematological malignancies.

• Efficacy of many chemotherapeutics and targeted therapies is dictated by cellular ceramide levels.

• Oncogene activation skews sphingolipid metabolism to favour the production of pro-survival sphingolipids.

• Inhibitors of enzymes involved in ceramide metabolism exhibit promise in the relapsed-refractory setting.

• Anti-cancer activity of sphingosine kinase inhibitors provides several options for new drug combinations.

Open Questions

• What other clinically utilised drugs rely on increases in ceramide levels for their efficacy and can they be effectively partnered with other ceramide inducing agents?

• How does ceramide modulate the Bcl-2 family proteins, Mcl-1 and Bcl-2?

• Are sphingolipid enzyme inhibitors best suited in the frontline or relapsed-refractory setting?

"Double-hit" chronic lymphocytic leukemia: An aggressive subgroup with 17p deletion and 8q24 gain

Chronic lymphocytic leukemia (CLL) with 17p deletion (17p-) is associated with a lack of response to standard treatment and thus the worst possible clinical outcome. Various chromosomal abnormalities (including unbalanced translocations, deletions, ring chromosomes and isochromosomes) result in the loss of 17p and one copy of the TP53 gene. The objective of the present study was to determine whether the type of chromosomal abnormality leading to 17p- and the additional aberrations influenced the prognosis in a series of 195 patients with 17p-CLL. Loss of 17p resulted primarily from an unbalanced translocation (70%) with several chromosome partners (the most frequent being chromosome 18q), followed by deletion 17p (23%), monosomy 17 (8%), isochromosome 17q [i(17q)] (5%) and a ring chromosome 17 (2%). In a univariate analysis, monosomy 17, a highly complex karyotype (≥5 abnormalities), and 8q24 gain were associated with poor treatment-free survival, and i(17q) (P = .04), unbalanced translocations (P = .03) and 8q24 gain (P = .001) were significantly associated with poor overall survival. In a multivariate analysis, 8q24 gain remained a significant predictor of poor overall survival. We conclude that 17p deletion and 8q24 gain have a synergistic impact on outcome, and so patients with this "double-hit" CLL have a particularly poor prognosis. Systematic, targeting screening for 8q24 gain should therefore be considered in cases of 17p- CLL.

CD180 overexpression in follicular lymphoma is restricted to the lymph node compartment

BACKGROUND

Altered Toll-like receptor (TLR) expression levels and/or mutations in its signaling pathway (such as MyD88 mutation) contribute to the pathogenesis of lymphoproliferative disorders (LPD). CD180 is an orphan member of the TLR family that modulates the signaling of several TLRs, but only limited studies have evaluated its expression by flow cytometry (FCM) in LPD.

METHODS

Using a multiparameter FCM approach, we have assessed CD180 mean fluorescence intensity (MFI) in lymph nodes (LNs) and peripheral blood (PB) samples obtained from patients with follicular lymphoma (FL; LN/PB, n = 44/n = 15), chronic lymphocytic leukemia (CLL, n = 26/n = 21), mantle cell lymphoma (MCL, n = 13/n = 17), and marginal zone lymphoma (MZL, n = 16/n = 12). Specimens from non-tumoral PB and LN (n = 8/n = 12) were used as controls.

RESULTS

In the LN specimens, FL and control B-cells showed similar CD180 expression (MFI = 1,049 vs. 1,381, P > 0.05; Mann-Whitney U-test). This level was markedly lower in the other LPDs, MCL (MFI = 396, P < 0.05), or CLL (MFI = 502 P < 0.05), and similar to MZL (MFI = 858, P > 0.05). However, the CD180 expression of FL B-cells assessed in PB was dim and/or negative, in the same range as MCL and CLL (FL MFI = 453, MCL MFI = 305, CLL MFI = 420, P > 0.05) but lower than in MZL (MFI = 895, P < 0.05). Therefore, these results suggest a modulation of CD180 expression by neoplastic FL B-cells based on the anatomical compartment.

CONCLUSION

These FCM data confirm the usefulness of CD180 in the accurate diagnosis of LPDs and emphasize the need to interpret this marker according to the origin of the sample. © 2015 Clinical Cytometry Society.

Jumping translocations, a novel finding in chronic lymphocytic leukaemia

A jumping translocation (JT) is a rare cytogenetic aberration that can occur in haematological malignancy. It involves the translocation of the same fragment of donor chromosome onto two or more recipient chromosomes, typically in different cells. In this study, we describe the first series of chronic lymphocytic leukaemia (CLL) patients with JTs reported to date. Following a review of 878 CLL patient karyotypes, we identified 26 patients (3%) with 97 JTs. The most commonly occurring breakpoint in these translocations was 17p11.2. Loss of TP53 was identified prior to or at the same time as JT in 23 of 26 patients (88%). All patients eventually developed a complex karyotype. All but one patient has required treatment for CLL, with estimated median time to treatment of 11·5 months. This study establishes JTs as a recurrent abnormality found in CLL patients with aggressive disease. JTs contribute to complex karyotypes and, in many cases, are involved in chromosomal rearrangements that result in loss of the tumour suppressor gene TP53.

Peripheral blood involvement in patients with follicular lymphoma: a rare disease manifestation associated with poor prognosis

Follicular Lymphoma (FL) is the second most common non-Hodgkin lymphoma (NHL) subtype and its course is heterogeneous. At diagnosis, some patients with FL manifest a detectable leukaemic phase (FL-LP), but this feature has been seldom described and is poorly characterized. Among 499 patients diagnosed with FL in Lyon-Sud hospital, 37 (7·4%) had characteristic FL-LP (by cytological blood smears and flow cytometric analysis). In addition, 91/1135 FL patients from the PRIMA study presented FL-LP at study entry. In order to evaluate the outcome of this Lyon-Sud cohort, FL-LP patients were matched with 111 newly diagnosed FL without LP according to the Follicular Lymphoma International Prognostic Index (FLIPI) score, age and treatment. Presence of FL-LP was associated with shorter progression-free survival (PFS) and overall survival (OS) (P = 0·004 and P = 0·031, respectively). Presence of FL-LP and high FLIPI score remained independent prognostic factors in a Cox model for time to progression (TTP). A number of circulating lymphoma cells (CLC) >4 × 10(9) /l was the most significant predictor for a shorter TTP in this Cox model. The prognostic impact of FL-LP on TTP was validated in the PRIMA cohort (P = 0·0004). In conclusion, FL-LP is a rare event associated with shorter PFS and patients with CLC >4 × 10(9) /l have a poorer outcome. These patients should be monitored carefully to consider alternative therapeutic options.

In non-follicular lymphoproliferative disorders, IGH/BCL2-fusion is not restricted to chronic lymphocytic leukaemia

The translocation t(14;18) and its t(2;18) and t(18,22) variants, which involve the BCL2 genetic hallmark for follicular lymphoma (FL), have been reported in several cases of chronic B-cell lymphoproliferative disease (CLPD) and frequently in chronic lymphocytic leukaemia (CLL). We describe here the clinical, morphological, immunological, cytogenetic and molecular findings from 37 cases of t(14;18)-positive CLPD, identified from our series of non-FL B-cell neoplasms (n=993) that were routinely analysed in peripheral blood by conventional cytogenetics analyses. The FL diagnosis was excluded by morphology and immunology (the samples were CD10 negative in all cases). The BCL2 translocations were observed in 22 CLL cases, including 7 monoclonal B-cell lymphocytosis (MBL) cases re-classified according to the new International Workshop on CLL criteria, six small lymphocytic lymphoma (SLL) cases, 1 splenic marginal zone lymphoma (SMZL) case and eight cases of unclassifiable CLPD with overlapping CLL/MZL features. In the CLL cases, the IGH/BCL2 fusion was remarkably associated with trisomy 12 (13/22) and mutated IGHV status (20/21) and did not affect the outcome. Moreover, most of these CLLs harboured a low mutation load of BCL6 gene and unmutated FAS (CD95) loci, which points to a post-germinal-centre cellular origin.

The role of dicentric chromosome formation and secondary centromere deletion in the evolution of myeloid malignancy

Dicentric chromosomes have been identified as instigators of the genome instability associated with cancer, but this instability is often resolved by one of a number of different secondary events. These include centromere inactivation, inversion, and intercentromeric deletion. Deletion or excision of one of the centromeres may be a significant occurrence in myeloid malignancy and other malignancies but has not previously been widely recognized, and our reports are the first describing centromere deletion in cancer cells. We review what is known about dicentric chromosomes and the mechanisms by which they can undergo stabilization in both constitutional and cancer genomes. The failure to identify centromere deletion in cancer cells until recently can be partly explained by the standard approaches to routine diagnostic cancer genome analysis, which do not identify centromeres in the context of chromosome organization. This hitherto hidden group of primary dicentric, secondary monocentric chromosomes, together with other unrecognized dicentric chromosomes, points to a greater role for dicentric chromosomes in cancer initiation and progression than is generally acknowledged. We present a model that predicts and explains a significant role for dicentric chromosomes in the formation of unbalanced translocations in malignancy.

Dic(17;18)(p11.2;p11.2) is a recurring abnormality in chronic lymphocytic leukaemia associated with aggressive disease

Interphase cytogenetics are commonly used to identify clonal abnormalities in chronic lymphocytic leukemia (CLL) patients but fail to identify recurrent translocations that ultimately can direct more focused molecular characterization. Given the importance of del(17p13.1) in CLL outcome, we performed an extensive review of 1213 patients undergoing metaphase cytogenetics at our institution and identified 16 (1.3%) with a recurrent unbalanced translocation between the p arms of chromosomes 17 and 18 that results in a dicentric chromosome with loss of much of 17p and 18p. The dic(17;18)(p11.2;p11.2) was associated with a complex (three or more unrelated cytogenetic abnormalities) karyotype in 12 patients (75%) at the time that the abnormality was first identified, and eventually associated with a complex karyotype in 94% of patients. IGHV mutational analysis was un-mutated in 88% of cases where evaluation was possible. Except for one patient who was diagnosed with CLL incidentally during a workup for metastatic tonsillar cancer, all patients identified with dic(17;18)(p11.2;p11.2) met criteria for disease treatment, with a median time from diagnosis to first treatment of 15 months. Our data demonstrate that dic(17;18)(p11.2;p11.2) is a novel recurrent cytogenetic abnormality in CLL associated with early age at diagnosis and accelerated disease progression. Future efforts to identify genes disrupted by this translocation are warranted and ongoing.

CD5 expression identifies a subset of splenic marginal zone lymphomas with higher lymphocytosis: a clinico-pathological, cytogenetic and molecular study of 24 cases

BACKGROUND

Classically, splenic marginal zone B-cell lymphoma is characterized by the absence of CD5 expression. Cases of apparent splenic marginal zone B-cell lymphoma showing CD5 expression, as diagnosed by blood studies, have been described; however, in the absence of histological evidence, the correct diagnosis of these cases is controversial because of possible confusion with other CD5-positive small B-cell neoplasms.

DESIGN AND METHODS

We report a series of 24 CD5-positive, t(11;14)-negative cases of splenic marginal zone B-cell lymphoma diagnosed by flow cytometry studies of blood and histologically proven on spleen sections. Clinical data as well as morphological, immunological, cytogenetic and molecular characteristics were assessed to evaluate the similarities and differences of these cases with those of classical CD5-negative splenic marginal zone B-cell lymphoma.

RESULTS

The CD5 expression detected in blood by flow cytometry was confirmed in most cases by immunohistochemistry on spleen sections. In general, cases of CD5-positive and CD5-negative splenic marginal zone B-cell lymphoma did not appear different and, in particular, they showed similar karyotypic changes such as 7q deletion, trisomy 3, trisomy 18 and biased IGHV usage (i.e. VH1-2). The main differences were a higher lymphocyte count at diagnosis (8.15x10(9)/L versus 3.90x10(9)/L; P=0.005) and more frequent diffuse bone marrow infiltration (34% versus 8%; P=0.03) in the CD5-positive group. A tendency to a more mutated IGHV status in the CD5 positive cases was observed (80% versus 54.5%; (P=0.11). No significant differences in outcome were found in relation to CD5 expression.

CONCLUSIONS

This study confirms the existence of cases of CD5-positive splenic marginal zone B-cell lymphoma and shows that these cases are closely related to classical splenic marginal zone lymphoma. Whether or not CD5-positive splenic marginal zone B-cell lymphoma constitutes a true subset obviously requires the study of more cases.

Splenic red pulp lymphoma with numerous basophilic villous lymphocytes: a distinct clinicopathologic and molecular entity?

The presence of circulating villous lymphocytes (VLs) in lymphoma patients usually points to splenic marginal zone B-cell lymphoma (SMZL), even if the VLs can be found occasionally in other small B-cell lymphomas. However, those cells are variably described, and detailed cytologic characterization is often lacking. We identified lymphoma cases with numerous basophilic VLs among the large group of splenic lymphoma with VLs, and for further delineation, 37 cases with this particular cytology were analyzed. Patients, predominantly older men, presented with moderate lymphocytosis and splenomegaly without pancytopenia. The monoclonal B cells expressed IgM + D, IgM + G, IgM or IgG, as well as CD76 and CD11c, frequently CD103, and rarely CD123. Spleen sections were peculiar, with atrophic white pulp and a monomorphic diffuse lymphoma infiltration in a congested red pulp. Bone marrow infiltration was interstitial and intrasinusoidal without extensive fibrosis. Cytogenetic analysis showed a frequent absence of clonal aberrations (68%). Most cases (79%) were IgH mutated, with an overrepresentation of VH3 and VH4 gene families. These results, as well as the clinical evolution, show that those lymphoma cases represent a homogeneous group distinct from SMZL and reminiscent of hairy cell leukemia variant, perhaps corresponding to a separate lymphoma entity.

Angioimmunoblastic T-cell lymphoma: clinical and laboratory features at diagnosis in 77 patients

We retrospectively analyzed 77 patients with pathologically diagnosed angioimmunoblastic T-cell lymphoma from a single city. There were 43 men and 34 women; the median age was 64.5 years (range, 30-91 yr). Average time between first symptoms of the disease and diagnosis was 3.6 months. At diagnosis, peripheral nodes were present in all but 1 patient, and were generalized in 90% of cases. Constitutional symptoms were reported in 77% of cases and spleen enlargement in 51%. A cutaneous eruption--morbilliform, urticarial, or more polymorphic--was present in 45% of patients; in one-third of them, the eruption occurred after drug administration. Other clinical manifestations included pleuritis (22%); arthralgia or arthritis (17%); ear, nose, and throat involvement (14%); central or peripheral neurologic manifestations (10%); and ascites (5%). Most patients presented with advanced disease at diagnosis (bone marrow involvement in 60% of cases). The main laboratory abnormalities were elevated lactate dehydrogenase levels (71%), inflammatory syndrome (67%), hypergammaglobulinemia (50%), anemia (51%), and lymphopenia (52%). Auto- or disimmune manifestations were reported in one-third of patients: autoimmune hemolytic anemia was present at diagnosis in 19% of patients and thrombocytopenic purpura in 7%. Documented vasculitis was described in 12% of cases. Clonality was analyzed in lymph nodes in 47 patients: T-cell and B-cell clones were found in 45 (96%) and 20 (45%) patients, respectively. Chromosomal abnormalities were identified in 62% of cases: trisomies 3, 5, 18, 19, additional X chromosome, and deletion of chromosome 7 were the most common abnormalities. The current study underlines the diversity of presenting manifestations of angioimmunoblastic T-cell lymphoma.

The BRCA1/2 pathway prevents hematologic cancers in addition to breast and ovarian cancers

BACKGROUND

The present study was designed to test the hypothesis that inactivation of virtually any component within the pathway containing the BRCA1 and BRCA2 proteins would increase the risks for lymphomas and leukemias. In people who do not have BRCA1 or BRCA2 gene mutations, the encoded proteins prevent breast/ovarian cancer. However BRCA1 and BRCA2 proteins have multiple functions including participating in a pathway that mediates repair of DNA double strand breaks by error-free methods. Inactivation of BRCA1, BRCA2 or any other critical protein within this "BRCA pathway" due to a gene mutation should inactivate this error-free repair process. DNA fragments produced by double strand breaks are then left to non-specific processes that rejoin them without regard for preserving normal gene regulation or function, so rearrangements of DNA segments are more likely. These kinds of rearrangements are typically associated with some lymphomas and leukemias.

METHODS

Literature searches produced about 2500 epidemiology and basic science articles related to the BRCA pathway. These articles were reviewed and copied to a database to facilitate access. Meta-analyses of statistical information compared risks for hematologic cancers vs. mutations for the components in a model pathway containing BRCA1/2 gene products.

RESULTS

Deleterious mutations of genes encoding proteins virtually anywhere within the BRCA pathway increased risks up to nearly 2000 fold for certain leukemias and lymphomas. Cancers with large increases in risk included mantle cell lymphoma, acute myeloid leukemia, acute lymphocytic leukemia, chronic lymphocytic leukemia, and prolymphocytic leukemia. Mantle cell lymphoma is defined by a characteristic rearrangement of DNA fragments interchanged between chromosomes 11 and 14. DNA translocations or rearrangements also occur in significant percentages of the other cancers.

CONCLUSION

An important function of the BRCA pathway is to prevent a subgroup of human leukemias and lymphomas that may involve non-random, characteristic gene rearrangements. Here, the genetic defect in BRCA pathway deficiencies is a chromosomal misrepair syndrome that may facilitate this subgroup of somatic cancers. Inactivation of a single gene within the pathway can increase risks for multiple cancers and inactivation of a different gene in the same pathway may have similar effects. The results presented here may have clinical implications for surveillance and therapy.

Loss of 17p is a major consequence of whole-arm chromosome translocations in hematologic malignancies

To ascertain the distribution of whole-arm translocations (WATs) and their consequential imbalances in hematologic malignancies, we analyzed the imbalances related to chromosomes involved in clonal, acquired WATs in 140 consecutive tumors with WATs and near-diploid karyotypes. Tumors for analysis were obtained from a survey of the cytogenetic database in the Department of Medical Genetics, Henry Ford Health System, Detroit, MI. Of the 140 tumors, 9 had balanced WATs; the remaining 131 had WATs that rarely or never involved chromosome X, Y, 2, 3, 4, 6, 19, or 20. Chromosome arms were lost more often than they were gained, and short arms were lost more often than long arms, except for chromosomes 7 and 16 (more long arms lost than short) and chromosome 11 (both arms equally lost). The long arm of chromosome 1 was the only arm gained with substantial frequency, in 26% of tumors. Of WATs that resulted in gain of 1q, short arm of chromosome 7 and acrocentric long arms were involved in 47 and 24%, respectively. Acrocentric chromosomes were involved in acquired WATs in 45% of tumors (the D-group acrocentrics more than the G-group), and were more likely to be involved in non-Robertsonian than Robertsonian translocations (P < 0.001, normal test). Loss of 17p was the most common short-arm loss (23% of tumors) and often occurred as part of complex karyotypes suggestive of disease progression. The present findings show that acquired whole-arm chromosome translocations in hematologic malignancies are nonrandom, commonly involve acrocentric chromosomes, and often result in loss of 17p, which is often associated with advanced disease and poor prognosis in a wide spectrum of hematologic malignancies.

Novel Therapeutic Strategies With Alemtuzumab for Chronic Lymphocytic Leukemia

In the last 10 years purine analogs have become the chemotherapy of choice for the first-line treatment of chronic lymphocytic leukemia, principally because of their superior efficacy compared with alkylating agents. However, many patients experience a relapse after an initial response or become refractory to these agents. The introduction of immunotherapeutic agents has provided renewed hope for fludarabine-refractory patients. Several clinical trials have shown the efficacy of alemtuzumab in patients with fludarabine-refractory chronic lymphocytic leukemia, including those with poor prognostic factors. Current studies indicate that treatment with alemtuzumab can achieve remissions with undetectable residual disease, as assessed by highly sensitive methods such as quantitative polymerase chain reaction or 4-color flow cytometry. These results suggest new applications for alemtuzumab such as combination treatment with chemotherapeutics or immunotherapeutics, maintenance therapy, and in vivo bone marrow purging prior to transplantation. A number of clinical trials are under way assessing the role of alemtuzumab in these settings.

Cytogenetic analysis delineates a spectrum of chromosomal changes that can distinguish non-MALT marginal zone B-cell lymphomas among mature B-cell entities: a description of 103 cases

The purpose of this study was to document the frequency and distribution of karyotypic changes present at diagnosis in 103 non-MALT marginal zone cell lymphoma (MZL) patients. This cytogenetic analysis of a large cohort extends previous observations and allows the identification of new cytogenetic features. Abnormalities identified in more than 15% of patients included +3/+3q (37%), 7q deletions (31%), +18/+18q (28%), 6q deletions (19%), +12/+12q (15%) and 8p deletions (15%). Trisomy 3/3q, 7q deletions, +18 and +12 were seen in different combinations in more than 30% of patients in comparison to 2% in lymphocytic lymphomas/chronic lymphocytic leukemias, 1% in mantle cell lymphomas and 7% in follicular lymphomas. The marked propensity of these abnormalities to be recurrently associated with the same tumoral clone of individual karyotypes allowed the delineation of a cytogenetic profile that may help to distinguish non-MALT MZL among other mature B-cell neoplasms. If +3/3q, +12/+12q, and 6q, 7q and 8p deletions were significantly associated with clinical prognostic factors previously reported to influence survival and time to progression, patients displaying these abnormalities did not experience a significantly shorter time to progression.

Structural aberrations of chromosomes 17 and 12 in chronic B-cell disorders

OBJECTIVES

Genomic aberrations can now be identified in approximately 80% of chronic lymphocytic leukemia, small lymphocytic lymphoma (CLL/SLL) patients. In the present study, four new structural changes involving chromosomes 17 and 12 in CLL/SLL patients are described.

METHODS

Five patients were selected for inclusion in the present report among a total of 92 cases with diagnosis of CLL/SLL. Cytogenetic studies and fluorescence in situ hybridization (FISH) analysis to detect some of the most frequent cryptic aberrations occurring in CLL/SLL patients were performed. Clinical studies are also described.

RESULTS

Four cases showed structural rearrangements of chromosome 17. A psu dic(17;2)(p11.2;p21), leading to p53 deletion, was observed in a patient who developed a mixed cellularity Hodgkin's disease coexisting with the CLL/SLL in the same lymph node. Epstein Barr virus was detected in the Reed-Sternberg cells. Two cases had a balanced translocation t(2;17)(p21;q23). Both patients showed trisomy 12 and clonal evolution and one of them also had 11q deletion. In addition, a der(17)t(12;17)(q13;q25) as a part of a complex karyotype, and a complex translocation t(5;12;19) (q15;p11;q13) were also found. Four patients had an adverse clinical outcome and died because of disease progression.

CONCLUSIONS

Four unreported nonrandom chromosome aberrations in CLL/SLL patients, one of them who might represent a new recurrent abnormality, are described. These uncommon abnormalities, mostly associated with evolving disease, may have implications for the understanding of genetic events associated with disease progression in this pathology.

TP53 in hematological cancer: low incidence of mutations with significant clinical relevance

Inactivation of the wild-type p53 gene (TP53) by various genetic alterations is a major event in human tumorigenesis. More than 60% of human primary tumors exhibit a mutation in the p53 gene. Hematological malignancies present a rather low incidence of genetic alterations in this gene (10-20%). Nevertheless, epidemiological studies of the hematological malignancies indicate that the prognosis of patients with a mutation in the p53 gene is worse than those expressing the wild-type p53 protein. Correlations between drug resistance, altered apoptosis, and mutations in the p53 gene are found in hematological malignancies and leukemias. These issues, as well as the possibility of exploiting p53 and its various functions for new therapeutic strategies, are discussed in the present review.

Cytogenetic, FISH, and molecular studies in a case of B-cell chronic lymphocytic leukemia with karyotypic evolution

We report the clinical, cytogenetic, fluorescence in situ hybridization (FISH) and molecular findings in a 54-yr-old male patient diagnosed with B-cell chronic lymphocytic leukemia (B-CLL), who showed progression to a diffuse large B-cell lymphoma (Richter's syndrome). Genetic studies were performed at diagnosis and during the Richter's transformation (RT). A clonal karyotype with two dicentric chromosomes, psu dic(12,21)(q24;q10) and dic(17,18)(p11.2;p11.2), was found. Both rearrangements were confirmed by FISH. Molecular cytogenetics analysis using p53 probe showed monoallelic loss of this tumor suppressor gene in 43.8% and 77.3% of cells for the first and the second studies, respectively). In both studies, deletions of D13S319 (18% and 12% of cells) and D13S25 loci (13% and 12% of cells) at 13q14 were found. Polymerase chain reaction analysis showed the MBR/JH rearrangement of the bcl-2 gene. FISH studies using LSI bcl-2/IgH probe allowed quantifying the clonal cell population with this rearrangement (4% and 6.6% of cells at diagnosis and RT, respectively). To our knowledge, this is the first case with a psu dic(12,21) described in B-CLL. The low percentage of cells with the 13q14 deletion and bcl-2/IgH rearrangement suggests that they were secondary events that resulted from clonal evolution. Our patient had a short survival (9 months) and a clear lack of response to several therapeutic agents, confirming the association of p53 gene deletion and karyotypic evolution with disease progression.

Dicentric chromosome 3 associated with binucleated lymphocytes in atypical B-cell chronic lymphoproliferative disorder

Binucleated lymphocytes on blood smear are known in PPBL characterized by stable and polyclonal lymphocytosis, polyclonal increase of serum IgM, HLA DR7 and strong correlation with additional i(3q) and premature chromosome condensation. In this disorder some reports of clonal Ig rearrangement suggest a follow up of these patients with immunological and genetic studies. Binucleated lymphocytes are rarely described in other clonal B-CLPD as B-CLL or marginal zone B-cell lymphoma (MZL). Chromosome 3 abnormality is never described in B-CLL but trisomy 3 represents the most consistent abnormality characterizing the MZL. We report in a man without previous medical history an unusual B-CLPD with monoclonal lymphocytosis CD5-, characteristic cytology (particularly binucleated lymphocytes) and chromosomic abnormality as dicentric chromosome 3 never previously described in B-CLPD. In this case lymphocytosis is persistent and stable over 24 months, cytologic immunologic and chromosomic abnormalities are unchanged. We discuss the nosologic place of this atypical B-CLPD closely related to PPBL and MZL with at the moment, after 24 months, a quiet evolution that imply nevertheless a careful follow up with regular cytologic, immunological and genetic studies to clarify the issue.

Multiple cell cycle regulator alterations in Richter's transformation of chronic lymphocytic leukemia

To investigate the role of the cell cycle regulators p21(Waf1), p27(Kip1), retinoblastoma (Rb), and cyclin D1 in Richter's transformation of chronic lymphocytic leukemia (CLL), we analyzed 19 CLL and eight Richter's syndrome (RS) tumors, previously characterized for p53 and ARF/INK4a abnormalities. p21(Waf1)immunohistochemical expression was negative in 12 of 15 CLL (80%), whereas it was moderate or strong in three of seven RS (43%). p21(Waf1) gene was in germline configuration in all the tumors analyzed. Four immunohistochemical patterns of p53 and p21(Waf1) expression were observed: (1) p53-/p21- in 10 of 15 CLL (67%), but only in two of six RS (33%); (2) p53+/p21+ in three CLL (20%) and two RS (33%); (3) p53-/p21+ in one RS; and (4) p53++/p21- in two CLL and one RS. Two p53+/p21+ CLL evolved into RS. p53 mutations clustered around the p53++/p21- (two CLL and one RS) and p53-/p21- (one CLL and one RS) tumors. While the majority of CLL displayed strong p27 immunoreactivity, RS tumors were constantly p27-negative. p27(Kip1) gene was in germline configuration in all the tumors analyzed. Most CLL cases were negative for Rb expression. In contrast, all RS exhibited strong Rb expression. Cyclin D1 overexpression was only detected in one CLL evolving into RS and one RS. In conclusion, a p53+/p21- immunohistochemical pattern is shown exclusively by p53-mutated CLL/RS. Additionally, our results suggest a possible implication of moderate/strong p21(Waf1) expression, loss of p27 expression, and cyclin D1 overexpression in the Richter's transformation of CLL.

B-CLL cells are capable of synthesis and secretion of both pro- and anti-angiogenic molecules

Initial work has shown that clonal B cells from B-chronic lymphocytic leukemia (B-CLL) are able to synthesize pro-angiogenic molecules. In this study, our goal was to study the spectrum of angiogenic factors and receptors expressed in the CLL B cell. We used ELISA assays to determine the levels of basic fibroblast growth factors (bFGF), vascular endothelial growth factor (VEGF), endostatin, interferon-alpha (IFN-alpha) and thrombospondin-1 (TSP-1) secreted into culture medium by purified CLL B cells. These data demonstrated that CLL B cells spontaneously secrete a variety of pro- and anti-angiogenic factors, including bFGF (23.9 pg/ml +/- 7.9; mean +/- s.e.m.), VEGF (12.5 pg/ml +/- 2.3) and TSP-1 (1.9 ng/ml +/- 0.3). Out of these three factors, CLL B cells consistently secreted bFGF and TSP-1, while VEGF was expressed in approximately two-thirds of CLL patients. Of interest, hypoxic conditions dramatically upregulated VEGF expression at both the mRNA and protein levels. We also employed ribonuclease protection assays to assay CLL B cell expression of a variety of other angiogenesis-related molecules. These analyses revealed that CLL B cells consistently express mRNA for VEGF receptor 1 (VEGFR1), thrombin receptor, endoglin, and angiopoietin. Further analysis of VEGFR expression by RT-PCR revealed that CLL B cells expressed both VEGFR1 mRNA and VEGFR2 mRNA. In summary, these data collectively indicate that CLL B cells express both pro- and anti-angiogenic molecules and several vascular factor receptors. Because of the co-expression of angiogenic molecules and receptors for some of these molecules, these data suggest that the biology of the leukemic cells may also be directly impacted by angiogenic factors as a result of autocrine pathways of stimulation.

CD38 expression and secondary 17p deletion are important prognostic factors in chronic lymphocytic leukaemia

CD38 expression and chromosomal abnormalities are novel prognostic factors in chronic lymphocytic leukaemia (CLL). However, their value remains undetermined. CD38 was evaluated in 123 patients and chromosomal aberrations in 111 cases with fluorescence in situ hybridization (FISH). CD38 expression was found in 27% of the cases. In addition, seven out of 32 CD38- patients became CD38+ during evolution of the disease. Chromosomal abnormalities included isolated 13q deletion (40%), 12q trisomy (14%), 11q deletion (without 17p deletion) (14%) and 17p deletion (7%). CD38 expression was significantly associated with Binet stages B and C, atypical morphology and 11q deletion. On univariate analysis of survival estimates, advanced Binet stages, CD38+ phenotype, atypical morphology and 11q or 17p deletions were associated with shorter event-free survival (EFS), treatment-free interval (TFI) and overall survival (OS). Multivariate analysis identified both Binet stages and CD38 as independent prognostic factors with regard to EFS and TFI. However, CD38 appeared as an independent factor for OS when restricted to Binet stage A. Chromosomal aberrations were re-evaluated during evolution in 31 cases. The 17p deletion was the most frequent new chromosomal abnormality (35%) and significantly associated with death (64%). In conclusion, CD38 expression and secondary 17p deletion are important poor prognostic indicators, especially in Binet stage A CLL.

p53 abnormalities in splenic lymphoma with villous lymphocytes

The incidence and role of p53 abnormalities have not been reported in splenic lymphoma with villous lymphocytes (SLVL), the leukemic counterpart of splenic marginal zone lymphoma. Because p53 abnormalities correlate with progressive and refractory disease in cancer and isochromosome 17q has been described in SLVL, a low-grade lymphoma that behaves aggressively in a minority of patients, this study investigated p53 changes by molecular and immunophenotypic methods in samples from 59 patients. The p53 deletion was analyzed by fluorescence in situ hybridization, and p53 protein expression was assessed by immunocytochemistry in 35 of 59 cases and by flow cytometry in 20 of 35 patients. Ten patients (17%) had a monoallelic p53 loss, 3 (9%) of 35 nuclear protein expression by immunocytochemistry, and 2 (10%) of 20 by flow cytometry. Two patients had both deletion and protein expression. Direct sequencing of all p53 exons was used to delineate mutations in 9 of 11 patients with an identified abnormality. Mutations, both compromising p53 DNA binding, were identified in the 2 patients with deletion and protein accumulation. Kaplan-Meier analysis revealed a significantly worse survival for patients with p53 abnormalities. Although p53 abnormalities are infrequent in SLVL, they underlie a more aggressive disease course and poor prognosis. (Blood. 2001;97:3552-3558)

Lymphocyte predominance Hodgkin disease is characterized by recurrent genomic imbalances

Single-cell polymerase chain reaction (PCR) has been used as a tool to demonstrate clonality and B-cell origin of Reed-Sternberg (RS) cells in Hodgkin disease (HD). An analogous approach was used to investigate genomic imbalances in a (cyto)genetically poorly characterized subentity: lymphocyte predominance Hodgkin disease (LPHD). Nineteen cases of LPHD were selected for a comparative genomic hybridization (CGH) study. CGH was performed with degenerate oligonucleotide primed-PCR (DOP-PCR)-amplified DNA from 4-5 microdissected CD20+ malignant cells. All analyzed cases revealed a high number of genomic imbalances (average 10.8 per case), involving all chromosomes but the excluded 19, 22, and Y, indicating a high complexity of LPHD. The majority of detected aberrations were recurrent. Gain of 1, 2q, 3, 4q, 5q, 6, 8q, 11q, 12q, and X, and loss of chromosome 17 were identified in 36.8% to 68.4% of the analyzed cases. Some of them have also been found in non-Hodgkin lymphoma (NHL), and possibly represent secondary changes associated with disease progression. Gain of 2q, 4q, 5q, 6, 11q, however, are much more rarely observed in NHL and could be more specifically associated with LPHD. Particularly interesting is a frequent overrepresentation of chromosome arm 6q, a region usually deleted in NHL. Rearrangement of the BCL6 gene (3q27) demonstrated by cytogenetics and fluorescence in situ hybridization in 2 cases in this study suggests its contribution in pathogenesis of LPHD. In conclusion, the data show a consistent occurrence of genomic alterations in LPHD and highlight genomic regions that might be relevant for development and/or progression of this lymphoma entity.

Secondary chromosome changes in mantle cell lymphoma: cytogenetic and fluorescence in situ hybridization studies

To better define the incidence and nature of secondary chromosome anomalies in mantle cell lymphoma (MCL) carrying the t(11:14)/BCL1 rearrangement, cytogenetic and fluorescence in situ hybridization studies (FISH) were performed in 42 patients (39 classical histology, 3 blastoid variant), using 6q21, 9p21/p16, 13q14, 17p13/p53 and chromosome-12-specific probes. Karyotypes from 89 cases published in 5 recent series including patients diagnosed in a homogeneous fashion were reviewed. In our series, FISH confirmed the interpretation of the karyotype in all cases and disclosed cryptic chromosome deletions in a sizeable fraction of cases. One patient (2.4% of total) was found with a cryptic 9p21 deletion by FISH. Two cases (4.8%) had a 6q21 deletion at CCA and at FISH; +12 was found in three cases by CCA plus nine by FISH (28.6%); 13q14 deletion was found in six cases by CCA plus 16 by FISH (52.4%), 17p13 deletion in three cases by CCA plus 8 by FISH (26.2%). In 131 patients (42 present series plus 89 in the literature) secondary chromosome aberrations seen by conventional cytogenetic analysis in more than 5 cases included deletions/translocations (del/t) 6q15-23 [15 cases]; -13 [14 cases]; del/t 1p21-31 [12 cases]; +3q [11 cases]; del/t 17p [9 cases]; 8p translocations and del(Y) [8 cases each]; -20 [7 cases]; 13q14 deletion, del/t 11q22-23, del/t 9q, del(10)(q22q24), -20, -21, -22 and -X [6 cases each]. We arrived at the following conclusions: i) though no secondary anomaly is specific for MCL, there is a distinct profile of recurrent chromosome lesions in MCL with 1p21-31 deletions, 8p translocations, 11q22-23 anomalies having a strong association with CD5+ B-cell lymphomas of low-to-intermediate grade histology; ii) FISH enabled the detection of cryptic chromosome 12, 13q and 17p rearrangements in a sizeable fraction of cases; iii) 9p21/p16 deletions did not occur at a high incidence in this series, possibly because of the low number of cases with blastoid variant.

Abnormalities of the p53 Tumour Suppressor Gene in Mature B-cell Neoplasms

The p53 gene, located on the short arm of human chromosome 17 at 17p13, codes for a 393 aminoacid phosphoprotein, which acts as a transcription factor and is involved in the control of many different cellular processes. It is the most frequently mutated gene in neoplasia and mutations have been observed in 231 of the 393 codons, including all but one codon of the DNA binding domain. p53 abnormalities in mature B-cell lymphoproliferative disorders (B-LPDs) occur in up to 75% of cases and are mostly detected in patients with advanced clinical stages. B-LPDs encompass a heterogeneous group of clinically important lymphoid malignancies with a complex biology, varying natural history and prognosis that makes their classification and treatment difficult. Despite many publications concerning the role of p53 abnormalities in the development of B-LPDs and the prognostic implications of detecting aberrant p53 function, it is difficult to draw firm conclusions as studies have varied with respect to patient selection and classification and techniques used. This review focuses on the available data pertaining to p53 abnormalities in the different mature B-cell neoplasms and summarises the incidences of abnormalities, the mutation patterns encountered and their clinical significance.

Dicentric (17;18) in a case of atypical B-cell chronic lymphocytic leukemia

We report a new dic(17;18)(p11.2;p11.2) in a 61-year-old male patient diagnosed with atypical B-cell chronic lymphocytic leukemia. The dic(17;18)(p11.2;p11.2) was detected in 90%, 10%, and 100% of metaphases in the peripheral blood, bone marrow, and lymph node, respectively. Fluorescence in situ hybridization studies with chromosome 17 and 18 centromeric probes revealed the presence of two normal centromeres of both chromosomes 17 and 18. The centromere of one chromosome 17 was found together with the centromere of one chromosome 18, confirming the dicentric nature of the rearrangement. In addition, with the use of a 17p13.1 region probe, monosomy of the 17p13 region, where the Tp53 gene is located, was observed.

Chronic lymphocytic leukemia

Chronic lymphocytic leukemia continues to attract much basic and clinical research interest. Despite recent advances, the disease still has no established cure. Nonetheless, significant strides have been made in our understanding of the genetics, biology, and clinical staging of this disease. This understanding may improve our ability to segregate patients into subtypes that differ in their cytogenesis, propensity toward disease progression, or response to standard or innovative forms of therapy. Finally, several promising new modalities of treatment are being evaluated in clinical trials, involving novel drugs or drug-combinations, monoclonal antibodies, stem cell transplantation, or gene therapy.

Update on the biology of chronic lymphocytic leukemia

An understanding of the molecular biology of B-cell chronic lymphocytic leukemia (B-CLL) has led to the appreciation that several different B-cell diseases are represented under this name. Variability in the bcl-2 family of proteins, p53 mutation, or the presence of various chromosomal abnormalities corresponds to variability of the clinical course of disease and response to therapy. Differential expression of cell surface adhesion molecules by B-CLL cells have also been shown to influence clinical outcome, as have the expression of immune regulatory molecules (eg, CD80, CD40R, CD27 and CD79b). Recent work studying immunoglobulin-heavy chain gene rearrangement postulates at least two subsets of B-CLL originating from different stages of B-cell development and following different clinical courses. The knowledge that B-CLL is the final consequence of many different molecular perturbations may allow the development of chemotherapies, immunotherapies, and gene therapies that target the specific molecular defect in a given case of B-CLL.