Theodora Papadaki

Splenic marginal zone lymphoma proposals for a revision of diagnostic, staging and therapeutic criteria.

Since the initial description of splenic marginal zone lymphoma (SMZL) in 1992, an increasing number of publications have dealt with multiple aspects of SMZL diagnosis, molecular pathogenesis and treatment. This process has identified multiple inconsistencies in the diagnostic criteria and lack of clear guidelines for the staging and treatment. The authors of this review have held several meetings and exchanged series of cases with the objective of agreeing on the main diagnostic, staging and therapeutic guidelines for patients with this condition. Specific working groups were created for diagnostic criteria, immunophenotype, staging and treatment. As results of this work, guidelines are proposed for diagnosis, differential diagnosis, staging, prognostic factors, treatment and response criteria. The guidelines proposed here are intended to contribute to the standardization of the diagnosis and treatment of these patients, and should facilitate the future development of clinical trials that could define more precisely predictive markers for histological progression or lack of response, and evaluate new drugs or treatments.

The genetics of Richter syndrome reveals disease heterogeneity and predicts survival after transformation

Richter syndrome (RS) represents the development of diffuse large B-cell lymphoma in the context of chronic lymphocytic leukemia. The scarcity of biologic information about RS has hampered the identification of molecular predictors of RS outcome. We addressed this issue by performing a comprehensive molecular characterization of 86 pathologically proven RS. TP53 disruption (47.1%) and c-MYC abnormalities (26.2%) were the most frequent alterations, whereas common genetic lesions of de novo diffuse large B-cell lymphoma were rare or absent. By multivariate analysis, lack of TP53 disruption (hazard ratio, 0.43; P = .003) translated into significant survival advantage with 57% reduction in risk of death. An algorithm based on TP53 disruption, response to RS treatment, and Eastern Cooperative Oncology Group performance status had 80.9% probability of correctly discriminating RS survival (c-index = .809). RS that were clonally unrelated to the paired chronic lymphocytic leukemia phase were clinically and biologically different from clonally related RS because of significantly longer survival (median, 62.5 months vs 14.2 months; P = .017) and lower prevalence of TP53 disruption (23.1% vs 60.0%; P = .018) and B-cell receptor stereotypy (7.6% vs 50.0%; P = .009). The molecular dissection of RS into biologically distinct categories highlights the genetic heterogeneity of this disorder and provides clinically relevant information for refining the prognostic stratification of patients.

Molecular subsets of mantle cell lymphoma defined by the IGHV mutational status and SOX11 expression have distinct biologic and clinical features

Mantle cell lymphoma (MCL) is a heterogeneous disease with most patients following an aggressive clinical course, whereas others having an indolent behavior. We conducted an integrative and multidisciplinary analysis of 177 MCL to determine whether the immunogenetic features of the clonotypic B-cell receptors (BcR) may identify different subsets of tumors. Truly unmutated (100% identity) IGHV genes were found in 24% cases, 40% were minimally/borderline mutated (99.9%-97%), 19% significantly mutated (96.9%-95%), and 17% hypermutated (<95%). Tumors with high or low mutational load used different IGHV genes, and their gene expression profiles were also different for several gene pathways. A gene set enrichment analysis showed that MCL with high and low IGHV mutations were enriched in memory and naive B-cell signatures, respectively. Furthermore, the highly mutated tumors had less genomic complexity, were preferentially SOX11-negative, and showed more frequent nonnodal disease. The best cut-off of germline identity of IGHV genes to predict survival was 97%. Patients with high and low mutational load had significant different outcome with 5-year overall survival (OS) of 59% and 40%, respectively (P = 0.004). Nodal presentation and SOX11 expression also predicted for poor OS. In a multivariate analysis, IGHV gene status and SOX11 expression were independent risk factors. In conclusion, these observations suggest the idea that MCL with mutated IGHV, SOX11-negativity, and nonnodal presentation correspond to a subtype of the disease with more indolent behavior.

Cytogenetic aberrations and their prognostic value in a series of 330 splenic marginal zone B-cell lymphomas: a multicenter study of the Splenic B-Cell Lymphoma Group.

We conducted a retrospective collaborative study to cytogenetically characterize splenic marginal zone lymphoma (SMZL) and ascertain the prognostic value of chromosomal aberrations. Of 330 cases, 72% displayed an aberrant karyotype, 53% were complex, and 29% had a single aberration. The predominant aberrations were gains of 3/3q and 12q, deletions of 7q and 6q and translocations involving 8q/1q/14q. CD5 expression was detected in 39 of 158 cases (25%). The cytogenetic makeup of the CD5(+) group differed significantly from that of the CD5(-) group. Cases with unmutated IGHV were significantly associated with deletions of 7q and TP53. A strong association was noted between usage of the IGVH1-2 and deletion 7q, 14q alterations, and abnormal karyotype. On univariate analysis, patients with more than or equal to 2 aberrations, 14q alterations, and TP53 deletions had the shortest survival; 7q deletion did not affect survival. On multivariate analysis, cytogenetic aberrations did not retain prognostic significance; the parameters negatively affecting survival were hemoglobin and age. In conclusion, the cytogenetic profile of SMZL is distinct from other B-cell lymphomas. Complexity of the karyotype, 14q aberrations, and TP53 deletions are poor prognostic indicators and may be considered together with other clinicobiologic parameters to ascertain the prognosis of SMZL.

PLCG1 mutations in cutaneous T-cell lymphomas

Cutaneous T-cell lymphoma (CTCL) is a heterogeneous group of primary cutaneous T-cell lymphoproliferative processes, mainly composed of mycosis fungoides and Sézary syndrome, the aggressive forms of which lack an effective treatment. The molecular pathogenesis of CTCL is largely unknown, although neoplastic cells show increased signaling from T-cell receptors (TCRs). DNAs from 11 patients with CTCL, both normal and tumoral, were target-enriched and sequenced by massive parallel sequencing for a selection of 524 TCR-signaling-related genes. Identified variants were validated by capillary sequencing. Multiple mutations were found that affected several signaling pathways, such as TCRs, nuclear factor κB, or Janus kinase/signal transducer and activator of transcription, but PLCG1 was found to be mutated in 3 samples, 2 of which featured a redundant mutation (c.1034T>C, S345F) in exon 11 that affects the PLCx protein catalytic domain. This mutation was further analyzed by quantitative polymerase chain reaction genotyping in a new cohort of 42 patients with CTCL, where it was found in 19% of samples. Immunohistochemical analysis for nuclear factor of activated T cells (NFAT) showed that PLCG1-mutated cases exhibited strong NFAT nuclear immunostaining. Functional studies demonstrated that PLCG1 mutants elicited increased downstream signaling toward NFAT activation, and inhibition of this pathway resulted in reduced CTCL cell proliferation and cell viability. Thus, increased proliferative and survival mechanisms in CTCL may partially depend on the acquisition of somatic mutations in PLCG1 and other genes that are essential for normal T-cell differentiation.

Two main genetic pathways lead to the transformation of chronic lymphocytic leukemia to Richter syndrome

Richter syndrome (RS) occurs in up to 15% of patients with chronic lymphocytic leukemia (CLL). Although RS, usually represented by the histologic transformation to a diffuse large B-cell lymphoma (DLBCL), is associated with a very poor outcome, especially when clonally related to the preexisting CLL, the mechanisms leading to RS have not been clarified. To better understand the pathogenesis of RS, we analyzed a series of cases including 59 RS, 28 CLL phase of RS, 315 CLL, and 127 de novo DLBCL. RS demonstrated a genomic complexity intermediate between CLL and DLBCL. Cell-cycle deregulation via inactivation of TP53 and of CDKN2A was a main mechanism in the histologic transformation from CLL phase, being present in approximately one half of the cases, and affected the outcome of the RS patients. A second major subgroup was characterized by the presence of trisomy 12 and comprised one third of the cases. Although RS shared some of the lesions seen in de novo DLBCL, its genomic profile was clearly separate. The CLL phase preceding RS had not a generalized increase in genomic complexity compared with untransformed CLL, but it presented clear differences in the frequency of specific genetic lesions.

Over 30% of patients with splenic marginal zone lymphoma express the same immunoglobulin heavy variable gene: ontogenetic implications

We performed an immunogenetic analysis of 345 IGHV-IGHD-IGHJ rearrangements from 337 cases with primary splenic small B-cell lymphomas of marginal-zone origin. Three immunoglobulin (IG) heavy variable (IGHV) genes accounted for 45.8% of the cases (IGHV1-2, 24.9%; IGHV4-34, 12.8%; IGHV3-23, 8.1%). Particularly for the IGHV1-2 gene, strong biases were evident regarding utilization of different alleles, with 79/86 rearrangements (92%) using allele (*)04. Among cases more stringently classified as splenic marginal-zone lymphoma (SMZL) thanks to the availability of splenic histopathological specimens, the frequency of IGHV1-2(*)04 peaked at 31%. The IGHV1-2(*)04 rearrangements carried significantly longer complementarity-determining region-3 (CDR3) than all other cases and showed biased IGHD gene usage, leading to CDR3s with common motifs. The great majority of analyzed rearrangements (299/345, 86.7%) carried IGHV genes with some impact of somatic hypermutation, from minimal to pronounced. Noticeably, 75/79 (95%) IGHV1-2(*)04 rearrangements were mutated; however, they mostly (56/75 cases; 74.6%) carried few mutations (97-99.9% germline identity) of conservative nature and restricted distribution. These distinctive features of the IG receptors indicate selection by (super)antigenic element(s) in the pathogenesis of SMZL. Furthermore, they raise the possibility that certain SMZL subtypes could derive from progenitor populations adapted to particular antigenic challenges through selection of VH domain specificities, in particular the IGHV1-2(*)04 allele.

Molecular insights into the immunopathogenesis of follicular lymphoma

Follicular lymphoma is caused by the transformation of a germinal-center-derived B cell with a t(14;18) chromosomal translocation. The distribution of somatic mutations within immunoglobulin genes indicates that follicular-lymphoma cells can interact with antigen. In addition, nonimmunoglobulin genes such as BCL6 seem to undergo somatic hypermutation. Here, Kostas Stamatopoulos and colleagues relate the molecular data about immunoglobulin genes and the protooncogenes BCL2 and BCL6 to the pathogenesis and evolution of follicular lymphoma.

Evidence for T-large granular lymphocyte-mediated neutropenia in Rituximab-treated lymphoma patients: report of two cases

We report two cases with B cell malignancies (case #1: refractory mantle cell lymphoma; case #2: lymphocyte predominant Hodgkins disease (LPHD)) who developed neutropenia post-Rituximab therapy in a setting of significant infiltration of the peripheral blood (PB) and bone marrow (BM) by T cells with an immunophenotype of large granular lymphocytes. Possible pathogenetic mechanisms are discussed.

Acute lymphoplasmacytoid dendritic cell (DC2) leukemia: Results from the Hellenic Dendritic Cell Leukemia Study Group

We present a cohort of 22 patients with type 2 dendritic cell (DC2) acute leukemia (or blastic plasmacytoid dendritic cell neoplasm-BPDCN, as it has been recently named), diagnosed in Greece over the past 12-year period, according to the main clinical and immunophenotypic features of this entity. Four additional cases are discussed, classified as leukemia of ambiguous lineage (LAL), because of the simultaneous detection of a CD56 negative DC2 population and of a second myeloid precursor cell population. The morphological features and cytogenetic findings of the typical BPDCN cases were similar to those previously described. Acute lymphoblastic leukemia-type chemotherapeutic regimens were more efficient in controlling the disease. Immunophenotyping of typical BPDCN cases revealed CD4(+), CD56(+), HLA-DR(+) and CD123(bright) neoplastic cells, in the absence of major B-, T- and myeloid-associated markers, while the phenotype of the four cases characterized as LAL highlights the risk of misdiagnosis. Based on our experience, we propose a flow cytometric algorithmic approach for the distinction of typical BPDCN from certain types of acute myeloid leukemia, but also for the identification of acute myeloid leukemia, admixed with CD56 negative DC2 cells, which could be misdiagnosed as BPDCN.