Identification of two subgroups of mantle cell leukemia with distinct clinical and biological features

Leukemic Non-nodal Mantle Cell Lymphoma: Diagnosis and Treatment

OPINION STATEMENT

Mantle cell lymphoma (MCL) encompasses nearly 6% of all the non-Hodgkin lymphomas. It is considered an incurable neoplastic process arising from B cells. The cytogenetic abnormality t(11;14) (q13; q32) leading to cyclin D1 overexpression is the sentinel genetic event and provides an exceptional marker for diagnosis. MCL is generally considered to have an aggressive course as compared with other indolent lymphomas with traditionally reported median survival of 3-5 years. According to the 2016 WHO classification, there are two major known variants of MCL: classical which affects the lymph nodes and extra nodal sites and leukemic non-nodal MCL (L-NN-MCL) which characteristically involves the bone marrow, peripheral blood, and the spleen. It is important to distinguish between classical and leukemic non-nodal MCL since the latter variant of MCL follows a rather indolent course with a wait and watch approach in order to avoid overtreatment. However, a subset of patients with L-NN-MCL can transform into a more aggressive course requiring treatment. Current evidence suggests those patients with alteration in TP53 gene do not respond to standard chemotherapy agents and may need targeted therapy. In this review, we describe the characteristics of L-NN-MCL, its diagnosis, and management.

Smoldering mantle cell lymphoma

Background

Mantle cell lymphoma (MCL) is an aggressive disease, with poor prognosis and a limited survival. However, some patients with indolent MCL can survive beyond 7~10 years. These patients remain largely asymptomatic and can be in observation for a long time without any treatment. The process of “wait and watch” leaves these patients with the potential risk of evolution to classic, aggressive MCL. On the other hand, early treatment for these patients may not impact overall survival but rather affects the quality of life. Therefore, it is essential to clearly identify this type of indolent MCL at the time of diagnosis.

Results

Reported findings of indolent presentation of MCL include: lack of B symptoms, normal serum lactic dehydrogenase (LDH) and β2-microglobulin levels (β2M), low MCL-International Prognostic Index (MIPI) score, maximum tumor diameter less than 3 cm, spleen size < 20 cm, positron emission tomography/computerized tomography with the Standard Uptake Value max <6, Ki-67 less than 30%, with some particular immunophenotype, such as CD5 and CD38 negative, markedly increased CD23 positive lymphocytes proportions, high expression of CD200, kappa light chain restriction, without C-myc, TP53 and NOTCH1/2 mutations, non-blastoid/pleomorphic histology, and no tumor growth on reevaluation every 2~3 months (followed for at least 6 months). Imaging evaluation may only be performed in the presence of disease-related symptoms or organ involvement. Meanwhile, if novel nodal or extranodal lesion is found, biopsy is mandatory to exclude lymphoma.

Common clinopathological forms of indolent presentations include monoclonal B lymphocytosis with t (11; 14); “indolent leukemic” presentation of MCL with involvement of peripheral blood, bone marrow involvement, splenomegaly, and minimal lymphadenopathies and in situ lymphoma (often found in lymph nodes removed for other reasons, and in gastrointestinal biopsies).

Conclusions

Considering these distinct indolent clinical presentations with particular features in cytology and gene mutational status, we propose to include these MCL clinical presentations under the umbrella of “Smoldering Mantle Cell Lymphoma”.

B-cell prolymphocytic leukemia: a specific subgroup of mantle cell lymphoma

B-cell prolymphocytic leukemia (B-PLL) is a rare mature B-cell malignancy that may be hard to distinguish from mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL). B-PLL cases with a t(11;14) were redefined as MCL in the World Health Organization 2008 classification. We evaluated 13 B-PLL patients [7 being t(11;14)-positive (B-PLL+) and 6 negative (B-PLL-)] and compared them with MCL and CLL patients. EuroFlow-based immunophenotyping showed significant overlap between B-PLL+ and B-PLL-, as well as between B-PLL and MCL, whereas CLL clustered separately. Immunogenotyping showed specific IGHV gene usage partly resembling MCL. Gene expression profiling showed no separation between B-PLL+ and B-PLL- but identified 3 subgroups. One B-PLL subgroup clustered close to CLL and another subgroup clustered with leukemic MCL; both were associated with prolonged survival. A third subgroup clustered close to nodal MCL and was associated with short survival. Gene expression profiles of both B-PLL+ and B-PLL- showed best resemblance with normal immunoglobulin M-only B-cells. Our data confirm that B-PLL+ is highly comparable to MCL, indicate that B-PLL- also may be considered as a specific subgroup of MCL, and suggest that B-PLL is part of a spectrum, ranging from CLL-like B-PLL, to leukemic MCL-like B-PLL, to nodal MCL-like B-PLL.

Indolent mantle cell leukemia: a clinicopathological variant characterized by isolated lymphocytosis, interstitial bone marrow involvement, kappa light chain restriction, and good prognosis

BACKGROUND

Cases of mantle cell lymphoma with indolent behavior have been reported, but are poorly identified by current clinical risk models. Early studies found peripheral blood involvement to be an adverse prognostic factor; however, cases of a seemingly indolent variant of mantle cell lymphoma, characterized by peripheral blood involvement and minimal nodal disease, have been incompletely described, particularly with regard to bone marrow findings. We report a series of leukemic phase mantle cell lymphomas with a non-progressive or slowly progressive course.

DESIGN AND METHODS

Cases presenting with mantle cell lymphoma limited to the peripheral blood/bone marrow from 2000-2010 were identified. Diagnoses were established by morphology, flow cytometric analysis and requisite evidence of IGH-CCND1@ by fluorescence in-situ hybridization or t(11;14)(q13;q32) by cytogenetics. Patients with lymphadenopathy, splenomegaly and gastrointestinal symptomatology were excluded.

RESULTS

Patients (n=8, median age 60.5 years) were asymptomatic with mild lymphocytosis (8.7×10(9)/L; range, 4.5-14.2×10(9)/L) and cytology typical of mantle cell lymphoma. Flow cytometric analysis showed that all expressed CD5, CD19, CD20, variable CD23, and a striking kappa immunoglobulin light chain restriction (7/8 cases). Bone marrow biopsy at diagnosis showed interstitial single or small lymphoid aggregates with similar patterns of CD20 and cyclin D1 immunostaining which were not readily discernable by hematoxylin and eosin stain. SOX11 was negative (4/5) or only weakly expressed (1/5). The median follow-up was 27 months (range, 5-109 months) and all patients, but one, are alive with no clinical evidence of disease. The prevalence of indolent mantle cell lymphoma presenting only with lymphocytosis, among all mantle cell lymphomas diagnosed during the same period, was 3%.

CONCLUSIONS

Leukemic mantle cell lymphoma limited to blood and bone marrow is an indolent variant characterized by mild-moderate lymphocytosis, interstitial low-level bone marrow involvement, simple karyotype, kappa light chain expression, cyclin D1 expression with lack of SOX11, and slow or absent clinical progression. Some cases may represent a mantle cell lymphoma counterpart to chronic lymphocytic leukemia - phenotype monoclonal B-cell lymphocytosis. Recognition of this variant could inform treatment decisions and possibly avoid unnecessary treatment.

Identification of uniquely expressed transcription factors in highly purified B-cell lymphoma samples

Transcription factors (TFs) are critical for B-cell differentiation, affecting gene expression both by repression and transcriptional activation. Still, this information is not used for classification of B-cell lymphomas (BCLs). Traditionally, BCLs are diagnosed based on a phenotypic resemblance to normal B-cells; assessed by immunohistochemistry or flow cytometry, by using a handful of phenotypic markers. In the last decade, diagnostic and prognostic evaluation has been facilitated by global gene expression profiling (GEP), providing a new powerful means for the classification, prediction of survival, and response to treatment of lymphomas. However, most GEP studies have typically been performed on whole tissue samples, containing varying degrees of tumor cell content, which results in uncertainties in data analysis. In this study, global GEP analyses were performed on highly purified, flow-cytometry sorted tumor-cells from eight subgroups of BCLs. This enabled identification of TFs that can be uniquely associated to the tumor cells of chronic lymphocytic leukemia (CLL), diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), hairy cell leukemia (HCL), and mantle cell lymphoma (MCL). The identified transcription factors influence both the global and specific gene expression of the BCLs and have possible implications for diagnosis and treatment.

Characterization of genetic changes in MCL by interphase FISH on tissue sections

Mantle cell lymphoma is a clinically heterogeneous disease, where further elucidation of pathogenetic mechanisms and better prognostic information is required. We evaluated genetic aberrations by interphase FISH on tissue sections or cytological material in 38 samples from 30 MCL patients, including 5 cases with cyclin D1 3'UTR low, which previously has been associated to unfavourable prognosis. The findings have been related to proliferation and clinical outcome. All but one of MCL showed t(11:14) translocation and in 22/30 samples taken at diagnosis or first relapse, one or several cytogenetic changes were detected; 11 deletions of ATM, 13 p53 deletions, 8 numerical c-myc-aberrations and 6 delp16. All but one MCL with low cyclin D1 3'UTR had additional cytogenetic changes, however no particular genetic change was strictly associated with this MCL variant. One fourth of MCL had none of the investigated additional aberrations and these tumours were in general less proliferative and some of these patients had a very long survival.

Comprehensive genetic characterization of CLL: a study on 506 cases analysed with chromosome banding analysis, interphase FISH, IgVH status and immunophenotyping

In CLL data from chromosome banding analysis (CBA) have been scarce due to the low proliferative activity of CLL cells in vitro. We improved the cultivation technique using an immunostimulatory CpG-oligonucleotide DSP30 and IL-2. A total of 506 CLL samples were analysed with CBA and interphase FISH using probes for the detection of trisomy 12, IgH rearrangements and deletions of 6q21, 11q22.3 (ATM), 13q14 (D13S25 and D13S319) and 17p13 (TP53). A total of 500 of 506 (98.8%) cases were successfully stimulated for metaphase generation and are subject to this study. Aberrations were detected in 415 of 500 (83.0%) cases by CBA and in 392 of 500 (78.4%) cases by FISH. CBA detected 832 abnormalities and FISH only 502. Therefore, CBA offers important information in addition to FISH. (1) CLL is characterized mainly by genomic imbalances and reciprocal translocations are rare. (2) A subgroup with complex aberrant karyotype (16.4%) is identified which is associated with an unmutated IgV(H) status and CD38 expression (P=0.034 and 0.02, respectively). (3) Additional abnormalities are detectable providing new biological insights into different CLL subclasses revealing a much more heterogeneous pattern of cytogenetic abnormalities as assumed so far based on FISH data only. Therefore, prospective clinical trials should evaluate the prognostic impact of newly available CBA data.

Leukemic involvement is a common feature in mantle cell lymphoma

BACKGROUND

The reported incidence of peripheral blood involvement in patients with mantle cell lymphoma (MCL) ranges from 13% to 77%. The aim of the study was to analyze the prevalence and the biologic and clinical significance of leukemic involvement in a series of patients with MCL.

METHODS

Leukemic expression was assessed by conventional morphology and flow cytometry (FC) in 48 patients. In addition, comparative genomic hybridization (CGH) was performed in 27 patients.

RESULTS

At diagnosis, 44 patients (92%) had evidence of leukemic expression by FC, including 8 patients (17%) without morphologically apparent leukemic involvement. Moreover, a lymphocyte count > or =5 x 10(9)/L was observed in 25 cases (52%). The most frequent imbalances detected by CGH were gains of 3q, 7p, 8q, 9q, 12q, and 13q, and losses of 13q, 1p, 9p, 11q, 10p, 17p, 6q, 8p, and 9q. Using a cutoff of 5 x 10(9)/L lymphocytes, cases with lymphocytosis more frequently presented with gains of 3q (P = .02), losses of 10p (P = .05), a low response rate (P = .04), and a short survival (P = .05).

CONCLUSIONS

Leukemic expression at diagnosis detected by FC was found to be highly frequent in this series of patients with MCL. Although morphologically apparent leukemic expression was not associated with specific chromosomal alterations detected by CGH, a lymphocyte count > or =5 x 10(9)/L was correlated with particular genetic abnormalities and a poor outcome.

IgVH genes mutation and usage, ZAP-70 and CD38 expression provide new insights on B-cell prolymphocytic leukemia (B-PLL)

B-prolymphocytic leukemia (B-PLL) is a rare disease with poor prognosis. To further characterize the biological features of this disease, we analyzed immunoglobulin heavy chain (IgVH) mutations, ZAP-70 and CD38 in 19 cases with de novo B-PLL. Immunoglobulin heavy chain genes analysis showed an unmutated pattern (>98% homology to germ line) in 9/17 cases (53%), with 100% homology in eight. In the remaining, it ranged from 90 to 97.4%, with three cases slightly mutated (98-95%) and five heavily mutated (<95%). All B-PLL utilized members of VH3 (11/17) and VH4 (6/17) families, with V3-23, V4-59 and V4-34 gene accounting for more than half of them, regardless of mutational status. ZAP-70, assessed by flow cytometry, ranged from 1 to 91% cells, being > or =20% in 57% of cases. CD38 ranged from 1 to 99% (median 21%). There was no correlation between IgVH status and ZAP-70 or CD38 expression, but male gender and del(17p) were more common in the unmutated group. Neither IgVH mutations, CD38 expression nor del(17p) influenced patients' outcome. Unexpectedly, ZAP-70+ B-PLL patients survived longer (40 months) than ZAP-70- B-PLL (8 months). B-PLL appears biologically heterogeneous regarding IgVH mutations, ZAP-70 and CD38 expression, showing a pattern distinct from that of other lymphoproliferative disorders.

Alteration ofAKAP220, an upstream component of the Rb pathway, in oral carcinogenesis

Few genes have been implicated in the development of oral cancer. In our study, we identified a novel gene in the Rb pathway that is frequently altered and overexpressed in oral tumors. Significantly, the alteration is also associated with early oral premalignant lesions (OPLs). This region was identified through a genomewide scan using randomly amplified polymorphic DNA (RAPD) PCR of 40 microdissected oral squamous cell carcinomas (SCCs). Recurrent gain of a approximately 400 bp signal was observed in multiple patients. This gain was localized to 13q14.11, a region frequently altered in multiple cancer types. Through microsatellite analysis, a 1.9 Mbp minimal region of alteration (MRA) was defined between D13S263 and D13S1227. Allelic imbalance (AI) in the MRA was present in only 28% of low-grade dysplasia, but strikingly increased with progression to 64% in high-grade dysplasia, plateauing at 61% in tumors, thus implicating this alteration in the early stages of disease development. Of the 3 genes residing within the MRA, Receptor Activator of NK-kappa-B Ligand (RANKL) and Diacylglycerol Kinase (DGKH) showed no change in expression levels in tumors compared to normal tissue. In contrast, 12 of 16 tumors showed significant overexpression of A-Kinase Anchoring Protein 220 (AKAP220). Since AKAP220 plays a role in regulating the Rb pathway, its dysregulation may contribute significantly to alterations in cell cycle regulation that facilitate progression of OPLs.

The role of molecular studies in lymphoma diagnosis: a review

Lymphoma classification is based on a multiparametric approach to diagnosis, in which clinical features, morphology, immunophenotype, karyotype and molecular characteristics are important to varying degrees. While in most cases, a diagnosis can be confidently established on the basis of morphology and immunophenotype alone, a small proportion of diagnostically difficult cases will rely on molecular studies to enable a definitive diagnosis. This review discusses the various molecular techniques available including Southern blotting (SB), polymerase chain reaction (PCR), fluorescence in situ hybridisation (FISH)--including multicolour-FISH/spectral karyotyping and comparative genomic hybridisation--and also gene expression profiling using cDNA microarray technology. Emphasis is given to the analysis of antigen receptor gene rearrangements and chromosomal translocations as they relate to lymphoma diagnosis and also in the setting of minimal residual disease (MRD) detection and monitoring. Laboratories performing these tests need to have expertise in these areas of testing, and there is a need for greater standardisation of molecular tests. It is important to know the sensitivity and specificity of each test as well as its limitations and the pitfalls in the interpretation of results. Above all, results of molecular testing should never be considered in isolation, and must always be interpreted in the context of clinical and other laboratory data.

Molecular cytogenetic characterization of the mantle cell lymphoma cell line GRANTA-519

Combining fluorescence R-banding, fluorescence in situ hybridization and spectral karyotyping allowed us to precisely define chromosomal breakpoints, gains, losses and a newly detected amplification in the human mantle cell lymphoma (MCL) cell line GRANTA-519. GRANTA-519 is characterized by the t(11;14)(q13;q32) resulting in overexpression of cyclin D1, a key player in cell cycle control. Hitherto unresolved complex rearrangements involve 1p, 1q, 3cen, 9p, 11q, 12p, 12q, 16p, 17p, and 18cen. Moreover, a 4- to 6-fold gain of sequences on 18q leads to a low-level amplification of the BCL2 gene and to an overexpression of the BCL2 protein. These results provide the basis for the identification of not only candidate oncogenes responsible for MCL in gained regions, but also for the identification of putative tumor suppressor genes in commonly deleted regions like 1p22, which would eventually enable functional studies of these genes.

Blastoid mantle cell lymphoma: evidence for nonrandom cytogenetic abnormalities additional to t(11;14) and generation of a mouse model

Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32), which is associated with cyclin D1 hyperexpression and a poor prognosis. MCL cases have been shown to progress to a more aggressive disease but the molecular events responsible of this phenomenon have not been determined. We have established two cell lines from the pleural effusions of two patients with MCL that we have used for further cytogenetic characterization to better define the incidence and nature of secondary chromosome abnormalities using multicolor fluorescence in situ hybridization, whole chromosome paint, and specific probes. Both cell lines grew independently without growth factors. Using CCND1/IGH-specific probes, patient UPN1 was found to have a masked t(11;14). Numerous and complex chromosomal abnormalities were found in both cell lines affecting chromosomes 2, 8, 13, 18, 22, X, and Y. These abnormalities included 8p losses, suggesting the presence of an anti-oncogene in this region, rearrangements of 8q24, MYC gene, and translocations involving 8, X, and Y chromosomes, which might be significant in the pathogenesis of MCL progression. The use of the cell lines (UPN1) allowed us to generate a mouse model of human MCL, mimicking a disseminated lymphoma and leading to the death of the animals in 4 weeks. This blastoid MCL model could be of major interest to determine molecular events involved in MCL progression, allowing isolation of involved genes and their functional characterization, and to study the effects of new chemotherapy regimens in mouse models.