Expression in non-Hodgkin's lymphoma of the bcl-2 protein associated with the t(14;18) chromosomal translocation

Treatment of indolent lymphoma

Treatment of indolent lymphoma has improved significantly in recent decades since the advent of rituximab (anti-CD20 monoclonal antibody). Although, some patients with limited disease can be cured with radiation therapy alone, most patients experience disease progression and recurrence during follow-up despite early initiation of treatment. Thus, watch-and-wait is still regarded the standard for asymptomatic patients. Patients with indolent lymphoma have a significant heterogeneity in terms of tumor burden, symptoms (according to anatomical sites) and the need for instant therapy. Therefore, the initiation of treatment and treatment option should be decided with a clear goal in each patient according to the need for therapy and clinical benefits with the chosen treatment. In this review, we cover the current treatment of follicular lymphoma and marginal zone lymphoma.

Loss-of-function of Fbxo10, encoding a post-translational regulator of BCL2 in lymphomas, has no discernible effect on BCL2 or B lymphocyte accumulation in mice

Regulation of the anti-apoptotic BCL2 protein determines cell survival and is frequently abnormal in B cell lymphomas. An evolutionarily conserved post-translational mechanism for over-expression of BCL2 in human B cell lymphomas and the BCL2 paralogue CED-9 in Caenorhabditis elegans results from loss-of-function mutations in human FBXO10 and its C.elegans paralogue DRE-1, a BCL2/CED-9-binding subunit of the SKP-CULLIN-FBOX (SCF) ubiquitin ligase. Here, we tested the role of FBXO10 in BCL2 regulation by producing mice with two different CRISPR/Cas9-engineered Fbxo10 mutations: an Asp54Lys (E54K) missense mutation in the FBOX domain and a Cys55SerfsTer55 frameshift (fs) truncating mutation. Mice homozygous for either mutant allele were born at the expected Mendelian frequency and appeared normal in body weight and appearance as adults. Spleen B cells from homozygous mutant mice did not have increased BCL2 protein, nor were the numbers of mature B cells or germinal centre B cells increased as would be expected if BCL2 was increased. Other lymphocyte subsets that are also regulated by BCL2 levels also displayed no difference in frequency in homozygous Fbxo10 mutant mice. These results support one of two conclusions: either FBXO10 does not regulate BCL2 in mice, or it does so redundantly with other ubiquitin ligase complexes. Possible candidates for the latter include FBXO11 or ARTS-XIAP. The difference between the role of FBXO10 in regulating BCL2 protein levels in C. elegans and in human DLBCL, relative to single-gene deficient mouse leukocytes, should be further investigated.

MYC's Fine Line Between B Cell Development and Malignancy

The transcription factor MYC is transiently expressed during B lymphocyte development, and its correct modulation is essential in defined developmental transitions. Although temporary downregulation of MYC is essential at specific points, basal levels of expression are maintained, and its protein levels are not completely silenced until the B cell becomes fully differentiated into a plasma cell or a memory B cell. MYC has been described as a proto-oncogene that is closely involved in many cancers, including leukemia and lymphoma. Aberrant expression of MYC protein in these hematological malignancies results in an uncontrolled rate of proliferation and, thereby, a blockade of the differentiation process. MYC is not activated by mutations in the coding sequence, and, as reviewed here, its overexpression in leukemia and lymphoma is mainly caused by gene amplification, chromosomal translocations, and aberrant regulation of its transcription. This review provides a thorough overview of the role of MYC in the developmental steps of B cells, and of how it performs its essential function in an oncogenic context, highlighting the importance of appropriate MYC regulation circuitry.

Molecular pathogenesis of germinal center-derived B cell lymphomas

B cell lymphomas comprise a heterogeneous group of genetically, biologically, and clinically distinct neoplasms that, in most cases, originate from the clonal expansion of B cells in the germinal center (GC). In recent years, the advent of novel genomics technologies has revolutionized our understanding of the molecular pathogenesis of lymphoid malignancies as a multistep process that requires the progressive accumulation of multiple genetic and epigenetic alterations. A common theme that emerged from these studies is the ability of lymphoma cells to co-opt the same biological programs and signal transduction networks that operate during the normal GC reaction, and misuse them for their own survival advantage. This review summarizes recent progress in the understanding of the genetic and epigenetic mechanisms that drive the malignant transformation of GC B cells. These insights provide a conceptual framework for the identification of cellular pathways that may be explored for precision medicine approaches.

Limited stage grade 3 follicular lymphoma patients can experience favorable outcomes with combined modality therapy

Controversy exists regarding the optimal management of limited stage grade 3 follicular lymphoma (FL3). We assessed the treatment outcomes of 190 consecutive patients with stage I-II FL. Fifty two patients had FL3 disease, in whom the median age was 55 years. At a median follow-up of 65 months, 5-year progression-free survival (PFS) and overall survival (OS) rates were 76.6% and 87.6%, respectively. Patients receiving systemic therapy followed by radiation therapy (RT) had a significantly better PFS (p=.003) than those treated with RT alone, but similar OS (p = .476). Patients treated with RT had 100% local control. Compared to 132 patients with grade 1-2 FL, those with FL3 had similar PFS (p = .493) and OS (p  =  .330). Patients with FL3 can experience favorable outcomes when treated with a combination of systemic therapy and RT, comparable to low grade FL.

How I treat early-relapsing follicular lymphoma

Follicular lymphoma (FL) is the most frequently occurring indolent non-Hodgkin lymphoma, with generally favorable outcomes but a variable clinical course. Recent studies have elucidated the consistent and reproducible frequency of early disease progression in FL, occurring in ∼20% of patients. Relapse of FL within 24 months of chemoimmunotherapy (POD24) is now established as a robust marker of poor survival, leading to increased risk of death. Currently, there is no established method of identifying patients at risk for early disease progression at the time of their FL diagnosis. However, numerous studies worldwide are investigating clinical, pathologic, and radiographic biomarkers to help predict POD24, thereby improving subsequent outcomes and adapting therapy based on individual risk. There is also a paucity of standardized treatments for patients with POD24, but investigations are ongoing testing novel targeted therapies and autologous stem cell transplantation strategies. This review provides an overview of early-relapsing FL and our approach to patient management based on recent available data.

Systemic lupus erythematosus and lymphoma: Incidence, pathogenesis and biology

Systemic Lupus Erythematosus (SLE), a well recognized systemic autoimmune disease is associated with an increased risk of malignancies, particularly lymphoma. Various studies have shown this risk to be as high as 4-7-fold compared to the general population. The pathogenesis of lymphoma in patients with SLE is still not well understood. In this review we summarize the world literature and update current knowledge on the interesting link between SLE and lymphomagenesis. We relate in turn to incidence rates of lymphoma in SLE and subtypes of lymphoma encountered; pathogenesis and relevant theories proposed; links with EBV and the possible role of continued activity of lupus and of immunosuppressive therapy in lymphomagenesis. It is clearly evident that further studies are needed to improve the understanding of this association. Some cytokines and proteins associated with cell survival and proliferation, such as BAFF, APRIL, IL6 and BCL2, have been found to be elevated both in SLE and lymphoma. These factors may well impact pathogenesis, however, a direct "cause and effect" relationship is yet to be demonstrated.

Mutual Risks of Cutaneous Melanoma and Specific Lymphoid Neoplasms: Second Cancer Occurrence and Survival

Background

It is unclear whether the established association between cutaneous melanoma (CM) and lymphoid neoplasms (LNs) differs across LN subtypes. This study quantifies risk for developing CM after specific LNs and, conversely, for developing specific LNs after CM, as well as assessing clinical impact.

Methods

We identified a cohort of Caucasian adults (age 20-83 years) initially diagnosed with CM or LN, as reported to 17 US population-based cancer registries, 2000-2014. Standardized incidence ratios (SIRs) quantified second cancer risk. We assessed impact of second cancer development on risk of all-cause mortality using Cox regression.

Results

Among 151 949 one-or-more-year survivors of first primary LN, second primary CM risk was statistically significantly elevated after chronic lymphocytic leukemia/small lymphocytic lymphoma (SIR = 1.96, 95% confidence interval [CI] = 1.74 to 2.21), follicular lymphoma (SIR = 1.32, 95% CI = 1.09 to 1.58), and plasma cell neoplasms (SIR = 1.33, 95% CI = 1.07 to 1.63). Risks for these same subtypes were statistically significantly elevated among 148 336 survivors of first primary CM (SIR = 1.44, 95% CI = 1.25 to 1.66; SIR = 1.47, 95% CI = 1.21 to 1.77; SIR = 1.25, 95% CI = 1.06 to 1.47; respectively). Risk for CM was statistically significantly elevated after diffuse large B-cell lymphoma (SIR = 1.22, 95% CI = 1.02 to 1.45) and Hodgkin lymphoma (SIR = 1.75, 95% CI = 1.33 to 2.26), but the reciprocal relationship was not observed. There were no statistically significant associations between marginal zone lymphoma and CM. Among survivors of most LN subtypes, CM statistically significantly increased risk of death (hazard ratio [HR] range = 1.52, 95% CI = 1.25 to 1.85, to 2.46, 95% CI = 1.45 to 4.16). Among survivors of CM, LN statistically significantly increased risk of death (HR range = 1.75, 95% CI = 1.15 to 2.65, to 6.28, 95% CI = 5.00 to 7.88), with the highest risks observed for the most aggressive LN subtypes.

Conclusions

Heterogeneous associations between CM and specific LN subtypes provide novel insights into the etiology of these malignancies, with the mutual association between CM and certain LN suggesting shared etiology. Development of second primary CM or LN substantially reduces overall survival.

Mass Cytometry of Follicular Lymphoma Tumors Reveals Intrinsic Heterogeneity in Proteins Including HLA-DR and a Deficit in Nonmalignant Plasmablast and Germinal Center B-Cell Populations

BACKGROUND

Follicular lymphoma (FL) is an indolent non-Hodgkin lymphoma that has a risk of transformation to more aggressive lymphoma. Relatively little is known about the nonmalignant B-cell and T-cell subset composition within the tumor microenvironment and whether altered phenotypes are associated with patterns of lymphoma B-cell heterogeneity.

METHODS

Two mass cytometry (CyTOF) panels were designed to immunophenotype B and T cells in FL tumors. Populations of malignant B cells, nonmalignant B cells, and T cells from each FL tumor were identified and their phenotypes compared to B and T cells from healthy human tonsillar tissue.

RESULTS

Diversity in cellular phenotype between tumors was greater for the malignant B cells than for nonmalignant B or T cells. The malignant B-cell population bore little phenotypic similarity to any healthy B-cell subset, and unexpectedly clustered closer to naïve B-cell populations than GC B-cell populations. Among the nonmalignant B cells within FL tumors, a significant lack of GC and plasmablast B cells was observed relative to tonsil controls. In contrast, nonmalignant T cells in FL tumors were present at levels similar to their cognate tonsillar T-cell subsets.

CONCLUSION

Mass cytometry revealed that diverse HLA-DR expression on FL cells within individual tumors contributed greatly to tumor heterogeneity. Both malignant and nonmalignant B cells in the tumor bore little phenotypic resemblance to healthy GC B cells despite the presence of T follicular helper cells in the tumor. These findings suggest that ongoing signaling interactions between malignant B cells and intra-tumor T cells shape the tumor microenvironment. © 2016 International Clinical Cytometry Society.

Apoptosis signaling and BCL-2 pathways provide opportunities for novel targeted therapeutic strategies in hematologic malignances

Apoptosis is an essential biological process involved in tissue homeostasis and immunity. Aberrations of the two main apoptotic pathways, extrinsic and intrinsic, have been identified in hematological malignancies; many of these aberrations are associated with pathogenesis, prognosis and resistance to standard chemotherapeutic agents. Targeting components of the apoptotic pathways, especially the chief regulatory BCL-2 family in the intrinsic pathway, has proved to be a promising therapeutic approach for patients with hematological malignances, with the expectation of enhanced efficacy and reduced adverse events. Continuous investigations regarding the biological importance of each of the BCL-2 family components and the clinical rationale to achieve optimal therapeutic outcomes, using either monotherapy or in combination with other targeted agents, have generated inspiring progress in the field. Genomic, epigenomic and biological analyses including BH3 profiling facilitate effective evaluation of treatment response, cancer recurrence and drug resistance. In this review, we summarize the biological features of each of the components in the BCL-2 apoptotic pathways, analyze the regulatory mechanisms and the pivotal roles of BCL-2 family members in the pathogenesis of major types of hematologic malignances, and evaluate the potential of apoptosis- and BCL-2-targeted strategies as effective approaches in anti-cancer therapies.

Same difference: A pilot study of cyclin D1, bcl-2, AMACR, and ALDH-1 identifies significant differences in expression between primary colon adenocarcinoma and its metastases

Tumor heterogeneity implies the possibility of significantly different expression of key pathways between primary and metastatic clones. Colon adenocarcinoma is one of the few tumors where current practice includes resection of primary and isolated organ metastases simultaneously without neoadjuvant therapy. We performed a pilot study on 28 cases of colon adenocarcinoma resected simultaneously with metastases in patients with no history of neoadjuvant therapy. We assayed matched primary and metastatic tumors from each patient with common diagnostic antibodies to Bcl-2, Cyclin D1, AMACR, and ALDH-1 by immunohistochemistry with semi-quantitative interpretation on archived formalin fixed, paraffin embedded samples. We were powered for large, consistent differences between primary and metastatic expression, and found 21 of 28 had a significant difference in expression of at least one of the four proteins, accounting for multiplicity of testing. Cyclin D1 had significantly more cases with differential metastatic:primary expression than would be expected by chance alone (p-value 0.0043), favoring higher expression in the metastatic sample. Bcl-2 and ALDH-1 had trends in this direction (p-value 0.078 each). Proportionately more cases with significant differences were identified when a liver metastasis was tested. We conclude differences in expression between metastatic and primary colon adenocarcinoma within the same patient exist, and may have therapeutic and biomarker testing consequences.

Follicular lymphoma: first-line treatment without chemotherapy for follicular lymphoma

Opinion statement: The optimal initial treatment of follicular lymphoma (FL) is not known, and initial management of patients varies considerably between providers and institutions. The assertion that patients with low tumor burden can be observed for a period of time is being challenged owing to the safety and tolerability of novel therapeutics and the movement of the field away from traditional chemotherapy agents. Single agent rituximab has become increasingly popular as initial management of patients with low tumor burden disease, and there is evidence that prolonged treatment with rituximab can improve progression-free survival (PFS) when compared to induction with rituximab or observation. Radioimmunotherapy (RIT) has similarly shown efficacy in low tumor burden disease. Novel agents such as lenalidomide, idelalisib, and ibrutinib are being studied in the first-line setting. Importantly, none of these strategies have demonstrated an improved overall survival in a randomized study versus observation. It is the opinion of the authors that endpoints such as PFS alone, while important, should not drive changes in management with limited resources. Composite endpoints including quality of life are more informative on the true impact of treatments on patients with follicular lymphoma. Providers should encourage all patients to be treated in the context of an appropriate clinical trial when possible. If a patient is not a clinical trial candidate, we typically treat patients with advanced stage and high tumor burden with chemoimmunotherapy. The decision to give maintenance rituximab is individualized to the patient, as there is no overall survival benefit. In patients with early stage disease, we favor consideration of radiation therapy if the patient is a candidate. Our initial recommendation to patients with advanced stage, low tumor burden disease, is close observation or "watch and wait." We have observed that most patients become comfortable over time with an observation approach. If a patient is not comfortable with this recommendation, we will use single agent rituximab. If the patient responds to therapy, we do not recommend maintenance rituximab in low tumor burden disease but rather prefer a retreatment strategy or an extended schedule of four additional doses of rituximab.

Clinical impact of molecular features in diffuse large B-cell lymphoma and follicular lymphoma

Our understanding of the pathogenesis and heterogeneity of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL) has been dramatically enhanced by recent attempts to profile molecular features of these lymphomas. In this article, we discuss ways in which testing for molecular features may impact DLBCL and FL management if clinical trials are designed to incorporate such tests. Specifically, we discuss how distinguishing lymphomas on the basis of cell-of-origin subtypes or the presence of other molecular features is prognostically and therapeutically significant. Conversely, we discuss how the molecular similarities of DLBCL and FL have provided insight into the potential of both DLBCL and FL cases to respond to agents targeting alterations they have in common. Through these examples, we demonstrate how the translation of our understanding of cancer biology into improvements in patient outcomes depends on analyzing the molecular correlates of treatment outcomes in clinical trials and in routinely treated patients.

Follicular lymphoma grade 3: review and updates

Follicular lymphoma (FL), Grade 3, is recognized as a distinct entity in the World Health Organization classification of lymphoma. It is further classified into Grade 3a and Grade 3b depending on the Bernard cell counting system and percentage of centroblasts. Grade 3 has molecular and genetic characteristics that distinguish it from other grades of FL. There is confusion and misunderstanding about the natural history and clinical course of Grade 3a and 3b because some studies indicate them as having indolent behavior and others describe more aggressive biology. The purpose of this article is to understand the concept of Grade 3 FL, especially the fundamental differences between Grade 3a and Grade 3b FL. Grade 3 FL is still an evolving subclass in FL and the practicing physician should understand the aggressive nature of Grade 3b, which typically requires timely attention, compared with Grade 3a. Grade 3a FL has more indolent characteristics but can possibly progress to Grade 3b and/or transform to diffuse large B-cell lymphoma at a future time. Nevertheless, large prospective studies are missing for an optimal evidence-based management approach for patients with Grade 3 FL at this time.

Follicular lymphoma in situ presenting as dermatopathic lymphadenopathy

Introduction. Follicular lymphoma in situ (FLIS) is a recently described entity with few cases recognized worldwide. To our knowledge, this is the first FLIS reported from West Africa. Case Presentation. We present the case of a 48-year-old civil servant with axillary lymphadenopathy discovered on routine mammography. On histology, a predominant reactive change with aggregates of melanophages was seen prompting a diagnosis of reactive lymphadenopathy. Immunohistochemistry done in our laboratory showed CD10 and Bcl-6 positive germinal centres with a small population of Bcl-2 positive germinal centre centre cells that were limited to some of the germinal centres. Conclusion. This highlights the use of immunohistochemistry in lymph node pathology—a resource which is very limited in our environment.

Immunophenotypic features and t(14;18) (q32;q21) translocation of Chinese follicular lymphomas helps to distinguish subgroups

Background

The revised 2008 World Health Organization classification maintains a histological grading system (grades 1–3) for follicular lymphoma (FL). The value of grading FL has been debated. This study will yield deeper insights into the morphologic, immunophenotypic characterization and t(14;18) translocation in FL and explore their significance of diagnosis of Chinese FL subgroups.

Methods

We retrospectively reviewed the FL diagnoses according to the 2008 WHO classification in all diagnostic specimens from a multicentric cohort of 122 Chinese patients. Upon review, 115 cases proved to be truly FL. CD10, BCL6, MUM1, BCL2 and t(14;18) (q32;q21) translocation were detected by Envision immunostaining technique and fluorescence in situ hybridization.

Results

FL1 has larger proportion of follicular pattern (93.0%) than that of FL2 (73.7%, P = 0.036), FL3B (63.6%, P = 0.003) and FL3A (77.4%, P = 0.053), although the last P value was more than 0.05 (Pearson’s chi-squared test). Areas of DLBCL were present in 25.8% (8/31) of FL3A and more frequent in FL3B (59.1%, 13/22; P = 0.015). The positivity of CD10 and BCL2 in FL1-2 were significantly higher than those in FL3 (P < 0.001, P = 0.043, respectively). The positivity of MUM1 in FL1-2 was significantly lower than that in FL3 (10.2% vs. 51.0%; P < 0.001). Furthermore the positivity of MUM1 in FL3A was significantly lower than that in FL3B (37.9% vs. 68.2%; P = 0.032). The positivity of t(14;18) was higher in FL1-2 than in FL3 (73.5% vs. 35.6%, P < 0.001), and was higher in FL3A than in FL3B (51.9% vs. 11.1%, P = 0.005). t(14;18) was significantly correlated with CD10+ (R = 0.453, P < 0.001) and MUM1+ (R = -0.482, P < 0.001).

Conclusions

FL1 and FL2 were immunophenotypically and genomically similar, while FL3A and FL3B were partly immunophenotypically similar but morphologically, genomically distinct. FL3A was genomically closer to FL1-2, whereas FL3A was genomically closer DLBCL. Thus we hypothesize that FL may in fact be a heterogeneous indolent lymphoma encompassing entities with distinct molecular pathogenesis and genetic characteristics. Immunohistochemical and genetic characterization helps to distinguish subgroups of FLs.

Virtual slides

The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1334018129864616.

Integration of genomic medicine into pathology residency training: the stanford open curriculum

Next-generation sequencing methods provide an opportunity for molecular pathology laboratories to perform genomic testing that is far more comprehensive than single-gene analyses. Genome-based test results are expected to develop into an integral component of diagnostic clinical medicine and to provide the basis for individually tailored health care. To achieve these goals, rigorous interpretation of high-quality data must be informed by the medical history and the phenotype of the patient. The discipline of pathology is well positioned to implement genome-based testing and to interpret its results, but new knowledge and skills must be included in the training of pathologists to develop expertise in this area. Pathology residents should be trained in emerging technologies to integrate genomic test results appropriately with more traditional testing, to accelerate clinical studies using genomic data, and to help develop appropriate standards of data quality and evidence-based interpretation of these test results. We have created a genomic pathology curriculum as a first step in helping pathology residents build a foundation for the understanding of genomic medicine and its implications for clinical practice. This curriculum is freely accessible online.

Melanoma in immunosuppressed patients

The immunogenic characteristics of malignant melanoma are intriguing. To date, multiple studies exist regarding the immunogenicity of melanoma. In this article, we summarize data in the literature on the role of immunosuppression in melanoma and discuss several immunocompromised patient populations in detail. A comprehensive PubMed search was conducted with no date limitation. The following search terms were used: melanoma in combination with immunosuppression, immunocompromised, genetics, antigen processing, UV radiation, organ transplantation, organ transplant recipients, lymphoproliferative disease, lymphoma, CLL, NHL, radiation, and HIV/AIDS. Although no formal criteria were used for inclusion of studies, most pertinent studies on the topic were reviewed, with the exception of smaller case reports and case series. The included studies were generally large (≥ 1000 patients in organ transplant recipient studies; ≥ 500 patients in lymphoma studies), with a focus on institutional experiences, or population-based national or international epidemiologic studies. Melanoma-induced immunosuppression, the role of UV radiation in melanoma development, and the epidemiology, clinical course, and prognosis of melanoma in immunocompromised patients are highlighted. Organ transplant recipients, patients with lymphoproliferative disorders, patients with iatrogenic immunosuppression, and patients with human immunodeficiency virus infection/AIDS are also highlighted. Recommendations are proposed for the care and monitoring of immunosuppressed patients with melanoma. With better understanding of the molecular microenvironment and clinical course of melanoma in immunosuppressed patients, novel therapies could be developed and outcomes potentially affected in these patients.

Genetics of primary intraocular tumors

Primary intraocular neoplasms are tumors that originate within the eye. The most common malignant primary intraocular tumor in adults is uveal melanoma and the second is primary intraocular lymphoma or vitreoretinal (intraocular) lymphoma. The most common malignant intraocular tumor in children is retinoblastoma. Genetics plays a vital role in the diagnosis and detection of ocular tumors. In uveal melanoma, monosomy 3 is the most common genetic alteration and somatic mutations of BAP1, a tumor suppressor gene, have been reported in nearly 50% of primary uveal melanomas. The retinoblastoma gene RB1 is the prototype tumor suppressor gene-mutations in RB1 alleles lead to inactivated RB protein and the development of retinoblastoma. Immunoglobulin heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement is observed in B-cell or T-cell primary vitreoretinal lymphoma, respectively. Other factors related to the genetics of these three common malignancies in the eye are discussed and reviewed.

Has the time to come leave the "watch-and-wait" strategy in newly diagnosed asymptomatic follicular lymphoma patients?

BACKGROUND

Historically, the median overall survival for follicular lymphoma (FL) has been considered to be 9-10 years, and no treatment had ever prolonged this time period. Studies conducted more than 20 years ago demonstrated that treating patients with asymptomatic FL at the onset of the disease did not increase their survival, and that almost 20% of these patients did not need any treatment in the first 10 years of follow-up. Based on these facts, most clinical practice guidelines recommend active surveillance policies for patients with asymptomatic FL.

DISCUSSION

The introduction of antiCD-20 monoclonal antibodies, over the last 15 years, has significantly increased the median survival rate to above 14 years. This improvement was achieved before the combination of rituximab and chemotherapy regimens became extensively used in patients with symptomatic disease. Therefore, this increase in survival may currently be more significant. At present, several clinical trials have evaluated low-toxicity therapies that prolong progression-free periods, among which rituximab monotherapy, radioimmunotherapy or the combination of rituximab with bendamustine are the most relevant. Unfortunately, these clinical trials have included only patients with symptomatic FL. The results of a recently reported clinical trial show that treatment with single-agent rituximab prolongs progression-free survival rates, time to new treatment and the quality of life of asymptomatic patients, as compared with the active surveillance strategy. Longer follow-up of these results and data regarding overall survival are awaited before this treatment can be recommended as the standard initial therapy.

SUMMARY

There are different therapeutic possibilities for asymptomatic FL patients, but no data are currently available to indicate which option is the best. Patients need to understand the risks and benefits of observation versus treatment before a final decision can be made. For patients who want active treatment the administration of four weekly rituximab doses should be considered.

Noxa/Bcl-2 protein interactions contribute to bortezomib resistance in human lymphoid cells

Previous studies have suggested that the BH3 domain of the proapoptotic Bcl-2 family member Noxa only interacts with the anti-apoptotic proteins Mcl-1 and A1 but not Bcl-2. In view of the similarity of the BH3 binding domains of these anti-apoptotic proteins as well as recent evidence that studies of isolated BH3 domains can potentially underestimate the binding between full-length Bcl-2 family members, we examined the interaction of full-length human Noxa with anti-apoptotic human Bcl-2 family members. Surface plasmon resonance using bacterially expressed proteins demonstrated that Noxa binds with mean dissociation constants (K(D)) of 3.4 nm for Mcl-1, 70 nm for Bcl-x(L), and 250 nm for wild type human Bcl-2, demonstrating selectivity but not absolute specificity of Noxa for Mcl-1. Further analysis showed that the Noxa/Bcl-2 interaction reflected binding between the Noxa BH3 domain and the Bcl-2 BH3 binding groove. Analysis of proteins expressed in vivo demonstrated that Noxa and Bcl-2 can be pulled down together from a variety of cells. Moreover, when compared with wild type Bcl-2, certain lymphoma-derived Bcl-2 mutants bound Noxa up to 20-fold more tightly in vitro, pulled down more Noxa from cells, and protected cells against killing by transfected Noxa to a greater extent. When killing by bortezomib (an agent whose cytotoxicity in Jurkat T-cell leukemia cells is dependent on Noxa) was examined, apoptosis was enhanced by the Bcl-2/Bcl-x(L) antagonist ABT-737 or by Bcl-2 down-regulation and diminished by Bcl-2 overexpression. Collectively, these observations not only establish the ability of Noxa and Bcl-2 to interact but also identify Bcl-2 overexpression as a potential mechanism of bortezomib resistance.

B-cell signaling networks reveal a negative prognostic human lymphoma cell subset that emerges during tumor progression

Human tumors contain populations of both cancerous and host immune cells whose malignant signaling interactions may define each patient's disease trajectory. We used multiplexed phospho-flow cytometry to profile single cells within human follicular lymphoma tumors and discovered a subpopulation of lymphoma cells with impaired B cell antigen receptor (BCR) signaling. The abundance of BCR-insensitive cells in each tumor negatively correlated with overall patient survival. These lymphoma negative prognostic (LNP) cells increased as tumors relapsed following chemotherapy. Loss of antigen receptor expression did not explain the absence of BCR signaling in LNP tumor cells, and other signaling responses were intact in these cells. Furthermore, BCR signaling responses could be reactivated in LNP cells, indicating that BCR signaling is not missing but rather specifically suppressed. LNP cells were also associated with changes to signaling interactions in the tumor microenvironment. Lower IL-7 signaling in tumor infiltrating T cells was observed in tumors with high LNP cell counts. The strength of signaling through T cell mediator of B cell function CD40 also stratified patient survival, particularly for those whose tumors contained few LNP cells. Thus, analysis of cell-cell interactions in heterogeneous primary tumors using signaling network profiles can identify and mechanistically define new populations of rare and clinically significant cells. Both the existence of these LNP cells and their aberrant signaling profiles provide targets for new therapies for follicular lymphoma.

Targeting the BCL-2 family in malignancies of germinal centre origin

The germinal centre is a dynamic microenvironment where B-cell responses are honed. Antigen-specific cells undergo clonal expansion followed by antibody affinity maturation and class switching through somatic hypermutation and recombination of immunoglobulin genes respectively. The huge proliferative capacity of the B-cells and the potential for generating non-functional or autoreactive immunoglobulins, necessitate strict control measures. Pro-apoptotic signalling pathways via B-cell receptors, FAS and the TGF-beta receptor, ALK5, ensure that apoptosis of germinal centre B-cells is the norm and cells only survive to differentiate fully if they receive sufficient pro-survival signals to overcome their 'primed for death' status. Several of the B-cell signalling pathways converge on the intrinsic apoptotic machinery to control expression of the BCL-2 family of apoptosis regulators including BIM, the pro-survival factor BCL-X(L) and the BH3-only protein, BIK (recently identified as a mediator of a TGF-beta-induced default apoptosis pathway in human B-cells). It is a foreseeable hazard that cells undergoing genetic mutation and recombination events might unintentionally target some of these factors, resulting in defective programmed cell death. Here we discuss the function of BCL-2 family proteins in germinal centre reactions, their deregulation in malignancies of germinal centre origin, and the potential for targeting BCL-2-related proteins therapeutically in lymphomas.

In VitroProliferation and Expansion of Hematopoietic Progenitors from Patients with Diffuse Large B-Cell Lymphoma Before and After Chemotherapy

We have previously demonstrated that when cultured in Dexter-type Long-Term Marrow Cultures (LTMC), hematopoietic progenitor cells (HPC) from patients with Diffuse Large B-Cell Lymphoma (DLBCL) show a defective proliferation, as compared to HPC from normal marrow. In that study it was also demonstrated that functional alterations were present in the hematopoietic microenvironment developed in culture; thus, it was not clear whether such a defective proliferation in vitro was due to an intrinsic defect in the HPC compartment of DLBCL patients, or to an altered microenvironment, or both. In order to address this question, in the present study we have assessed the proliferation and expansion potentials of HPC present in bone marrow from patients with DLBCL, in cytokine-supplemented liquid cultures initiated with a cell population enriched for CD34+ Lin- cells, in the absence of stromal cells and in the presence of reduced numbers of accessory cells. Our results demonstrated that bone marrow-derived HPC from patients with DLBCL, both before and right after chemotherapy, possessed reduced proliferation and expansion potentials in vitro, as compared to their normal counterparts. Interestingly, in patients analyzed 18 months after treatment the proliferation and expansion levels were similar to those of normal HPC, indicating a complete restoration of the hematopoietic function. Although the reason for these observations is not clear, our results suggest the possibility that primitive CD34+ progenitor cells present in bone marrow, which show deficient proliferation and expansion potentials in vitro, are involved in the origin/progression of DLBCL.

Follicular lymphomas

Follicular lymphomas constitute approximately 30% of all non-Hodgkin lymphomas. These lymphomas are characterized by at least partially follicular growth pattern, but diffuse areas may be present. The proportions of follicular or diffuse areas vary also from case to case, which seems to be associated with prognosis. Follicular lymphomas should not be divided into distinct subtypes, but rather shows a continuous gradation in the number of large cells. On the bases of this grading, three groups have been defined: grades 1-3. There is a consensus that grade 3 follicular lymphomas, namely grade 3b, should be discriminated from lower-grade cases. The cells of follicular lymphomas express surface immunoglobulin, more frequently IgM+/-IgD>IgG>IgA, B-cell-associated antigens, CD10+/-; they are CD5-, CD23-/+, CD43-, and CD11c-. Follicular lymphomas express bcl-2 proteins, which is useful in distinguishing reactive from neoplastic follicles. t(14;18) is present in 70-95% of follicular lymphomas, involving rearrangement of bcl-2 gene. Clinical behavior of follicular lymphomas is heterogeneous and differs according to the histologic grade and extension of disease. Moreover, the evaluation of these malignancies is conditioned by therapeutic decision, which is also determined by main prognostic factors. The International Prognostic Index for aggressive lymphomas is not optimal for follicular lymphomas. Conversely, the Italian Lymphoma Intergroup Index and, more recently, the Follicular Lymphoma International Prognostic Index (FLIPI), designed in pre-rituximab era, seem to correlate well with outcome. Several active therapeutic approaches from the "wait and watch" strategy to the allogeneic transplantation are available for management of patients with follicular lymphoma. Therapeutic decision is mostly conditioned by patient's characteristics, stage, histologic grade, tumor burden, and risk-predicting factors.

Intraocular lymphoma: update on diagnosis and management

BACKGROUND

Primary intraocular lymphoma (PIOL) is a subset of primary central nervous system lymphoma (PCNSL) in which lymphoma cells initially invade the retina, vitreous, or optic nerve head, with or without concomitant CNS involvement. The incidence of this previously rare condition has increased dramatically. Given its nonspecific presentation and aggressive course, PIOL provides a diagnostic and therapeutic challenge.

METHODS

We review the current strategies for diagnosis and treatment of PIOL and present our own experience with PIOL.

RESULTS

Recent developments in the diagnosis of PIOL include immunohistochemistry, flow cytometry, cytokine evaluation, and molecular analysis. However, definitive diagnosis still requires harvesting of tissue for histopathology. Optimal treatment for PIOL remains unclear. Initial therapeutic regimens should include methotrexate-based chemotherapy and radiotherapy to the brain and eye. In addition, promising results have been seen with intravitreal methotrexate and autologous stem cell transplantation for recurrent and refractory disease.

CONCLUSIONS

Efforts to further determine the immunophenotype and molecular characteristics of PIOL will continue to assist in the diagnosis of PIOL. Future studies are required to determine the role of radiotherapy and optimal local and systemic chemotherapeutic regimens.

Expression of apoptosis regulators in germinal centers and germinal center-derived B-cell lymphomas: insight into B-cell lymphomagenesis

Germinal centers (GC) are unique sites in peripheral lymphoid tissue where clonal selection of B cells takes place in response to stimulation by various antigens. To select a proper B-cell clone for antibody-mediated immunity, multiple apoptotic signals synchronize in the GC, both in negative and positive selection pathways. At the same time, GC have been known to be a major source of B-cell lymphomas including follicular and Burkitt's, and also some diffuse large B-cell lymphomas. Therefore, uncovering the biological characteristics of GC would greatly contribute to understanding lymphomagenesis, or progression of B-cell lymphomas of GC origin. Herein the authors briefly explain the expression and pathophysiological significance of apoptosis regulators in GC, focusing particularly on Bcl-2, Fas (CD95) and a transcription factor, nuclear factor of activated T cells, which seems to play a critical role in regulating cellular dynamics of GC B cells via B-cell antigen receptor. The expression of these molecules is then compared with that of the neoplastic counterpart B-cell lymphomas in order to consider lymphomagenesis of GC origin. In conclusion, follicular lymphoma closely reflected characteristics of GC among these B-cell lymphomas, although it acquires strong expression of apoptosis-resistant gene, bcl-2.

Haematopathology practice: the commonest problems encountered in a consultation practice

Although not specifically recognized as a subspecialty of histopathology, haematopathology has a long history of specialist practice in the UK, with a few centres attracting large numbers of referred cases. The specialist nature of haematopathology has been enhanced by the advent of immunohistochemistry and, more recently, molecular genetics, which now play a major role in the diagnosis of haematopoietic and lymphoid neoplasms. Problems encountered by non-specialist pathologists, and reflected in those cases submitted for consultation, include difficulties in the differential diagnosis of certain benign lymphoproliferative disorders from lymphoma and the precise classification of lymphomas which may have an impact on therapeutic decisions. Lymphomas that frequently pose problems include common lesions such as follicular lymphoma and more esoteric disorders such as T-cell/histiocyte-rich large B-cell lymphoma. This review is an attempt to clarify a logical approach to the differential diagnosis of these lesions.

Therapeutic targets in the mitochondrial apoptotic pathway

Every cell in the human body has most of the components of the apoptotic apparatus and is thus principally equipped to die by apoptosis. Situations of increased or decreased apoptosis contribute to many forms of human disease, making this pathway an attractive target of therapeutic intervention. The past few years have seen an enormous refinement in the understanding how apoptosis works on a molecular level and the role of mitochondria as a central element in apoptotic signal transduction has become obvious. Here, the authors consider the events that are critical in this mitochondrial pathway, in particular at mitochondria but also upstream and downstream. The authors' opinion is presented on the merits and feasibility of approaches that aim at treating disease by interfering with the mitochondrial apoptotic pathway.

Endogenous bcl-2 is not required for the development of Emu-myc-induced B-cell lymphoma

Although myc and bcl-2 synergize in tumor development, particularly lymphomagenesis, it is not known whether endogenous bcl-2 is required for myc-induced tumorigenesis. To investigate the role of endogenous Bcl-2 in myc-induced lymphomagenesis, we bypassed the early death of Bcl-2-deficient mice by reconstituting lethally irradiated wild-type (wt) mice with a hematopoietic system from fetal liver-derived stem cells of Emu-myc/bcl-2(-/-) or control Emu-myc transgenic embryos. In premalignant (healthy) recipients, loss of Bcl-2 caused a moderate decrease in pre-B and immature B cells, and a dramatic reduction of mature B lymphocytes expressing the Emu-myc transgene. Furthermore, cultured preneoplastic Emu-myc/bcl-2(-/-) mature B cells displayed accelerated apoptosis compared with Emu-myc B cells. However, despite the striking reduction in B-cell numbers in vivo, ablation of endogenous Bcl-2 did not prevent or even delay development of Emu-myc lymphoma. Moribund mice presented with similar degrees of splenomegaly, blood leukocyte numbers, and tumor dissemination at death. These findings demonstrate that the initiation, development, continued growth, and severity of Emu-myc lymphoma do not depend upon endogenous Bcl-2, nor upon the total number of B lymphoid cells driven by the Emu-myc transgene. These results have implications for the treatment of hematopoietic tumors, particularly those that are not caused by Bcl-2 overexpression.

Detection of the bcl-2 t(14;18) translocation and proto-oncogene expression in primary intraocular lymphoma

PURPOSE

Primary intraocular lymphoma (PIOL) is a diffuse large B cell lymphoma that initially infiltrates the retina, vitreous, or optic nerve head, with or without central nervous system involvement. This study examined the expression of the bcl-2 t(14;18) translocation, the bcl-10 gene, and high expression of bcl-6 mRNA in PIOL cells.

METHODS

Microdissection and PCR analysis were used to examine vitreous specimens in patients with PIOL for the presence of bcl-2 t(14;18) translocations, the bcl-10 gene, and expression of bcl-6 mRNA. A medical record review was also conducted to determine whether the bcl-2 t(14;18) translocation correlated with prognosis.

RESULTS

Forty of 72 (55%) PIOL patients expressed the bcl-2 t(14;18) translocation at the major breakpoint region. Fifteen of 68 (22%) patients expressed the translocation at the minor cluster region. The bcl-10 gene was detected in 6 of 26 (23%) patients, whereas 4 of 4 (100%) PIOL patients expressed higher levels of bcl-6 mRNA compared with inflammatory lymphocytes. An analysis of clinical outcome in 23 PIOL patients revealed no significant association between bcl-2 t(14;18) translocations and survival or relapse. However, patients with the translocation were significantly younger.

CONCLUSIONS

PIOL has unique molecular patterns of bcl-2, bcl-10, and bcl-6 when compared with other systemic lymphomas. This study lays the foundation for future studies aimed at exploring the genotypic classification of PIOL based on the quantitative molecular framework of gene expression profiling, with the goal of providing useful adjuncts to the pathologic diagnosis of this complex disease.

Altered B-cell receptor signaling kinetics distinguish human follicular lymphoma B cells from tumor-infiltrating nonmalignant B cells

The B-cell receptor (BCR) transmits life and death signals throughout B-cell development, and altered BCR signaling may be required for survival of B-lymphoma cells. We used single-cell signaling profiles to compare follicular lymphoma (FL) B cells and nonmalignant host B cells within individual patient biopsies and identified BCR-mediated signaling events specific to lymphoma B cells. Expression of CD20, Bcl-2, and BCR light chain isotype (kappa or lambda) distinguished FL tumor B-cell and nontumor host B-cell subsets within FL patient biopsies. BCR-mediated signaling via phosphorylation of Btk, Syk, Erk1/2, and p38 occurred more rapidly in tumor B cells from FL samples than in infiltrating nontumor B cells, achieved greater levels of per-cell signaling, and sustained this level of signaling for hours longer than nontumor B cells. The timing and magnitude of BCR-mediated signaling in nontumor B cells within an FL sample instead resembled that observed in mature B cells from the peripheral blood of healthy subjects. BCR signaling pathways that are potentiated specifically in lymphoma cells should provide new targets for therapeutic attention.

Linking tumor cell cytotoxicity to mechanism of drug action: an integrated analysis of gene expression, small-molecule screening and structural databases

An integrated, bioinformatic analysis of three databases comprising tumor-cell-based small molecule screening data, gene expression measurements, and PDB (Protein Data Bank) ligand-target structures has been developed for probing mechanism of drug action (MOA). Clustering analysis of GI50 profiles for the NCI's database of compounds screened across a panel of tumor cells (NCI60) was used to select a subset of unique cytotoxic responses for about 4000 small molecules. Drug-gene-PDB relationships for this test set were examined by correlative analysis of cytotoxic response and differential gene expression profiles within the NCI60 and structural comparisons with known ligand-target crystallographic complexes. A survey of molecular features within these compounds finds thirteen conserved Compound Classes, each class exhibiting chemical features important for interactions with a variety of biological targets. Protein targets for an additional twelve Compound Classes could be directly assigned using drug-protein interactions observed in the crystallographic database. Results from the analysis of constitutive gene expressions established a clear connection between chemo-resistance and overexpression of gene families associated with the extracellular matrix, cytoskeletal organization, and xenobiotic metabolism. Conversely, chemo-sensitivity implicated overexpression of gene families involved in homeostatic functions of nucleic acid repair, aryl hydrocarbon metabolism, heat shock response, proteasome degradation and apoptosis. Correlations between chemo-responsiveness and differential gene expressions identified chemotypes with nonselective (i.e., many) molecular targets from those likely to have selective (i.e., few) molecular targets. Applications of data mining strategies that jointly utilize tumor cell screening, genomic, and structural data are presented for hypotheses generation and identifying novel anticancer candidates.

Primary testicular and intraocular lymphomas: two case reports and a review of the literature

Testicular lymphoma is a rare neoplasm of the testis that is most commonly seen in older patients. It metastasizes preferentially to extranodal sites, including the skin, central nervous system, Waldeyer ring, contralateral testis, and lung. Two case reports of patients with a history of testicular lymphoma who developed involvement of the vitreous and retina are presented. These are interesting cases as the testis, central nervous system, and eye are all immune privileged organs, which may account for occurrence of disease in these sites. Histopathologic examination of diagnostic vitrectomy specimens from both cases showed atypical lymphoid cells with immunoglobulin heavy chain (IgH) gene rearrangements, consistent with the diagnosis of intraocular B-cell lymphoma. The results of a literature review of all reports of ocular involvement with testicular lymphoma are discussed. Patients with testicular lymphoma are at risk for relapse, particularly in the central nervous system. Clinicians should be suspicious for intraocular lymphoma in patients with a history of testicular lymphoma who present with vitritis or retinal lesions.

A prospective randomized study to compare the molecular response rates between central lymphatic irradiation and intensive alternating triple chemotherapy in the treatment of stage I–III follicular lymphoma

PURPOSE

This study was undertaken to compare the molecular response (MR) rates of 2 regimens, central lymphatic irradiation (CLI) and alternating triple therapy (ATT), in the treatment of Stage I-III follicular lymphoma. MR was defined as disappearance of t(14;18) (q32;q21) amplified by polymerase chain reaction (PCR).

PATIENTS AND METHODS

Sixty-five patients with Stage I to III follicular lymphoma were randomized. CLI consisted of the mantle, abdomen, and pelvic radiation fields. ATT alternated among CHOD-Bleo, ESHAP, and NOPP for 12 courses. Bone marrow (BM) and peripheral blood (PB) samples were obtained before treatment for PCR analysis. PCR-positive patients were followed by PCR analysis. The random-effects logistic model was fitted to the data from the posttreatment PCRs. The factors included in the model were treatment arm, type of PCR (BM vs. PB), and time to PCR sample procurement from the date of registration.

RESULTS

At a median follow-up of 71 months, the 5-year relapse-free survival (RFS) rates were 45% and 54% for CLI and ATT, respectively (p = 0.42). The probability of attaining an MR increased with time after registration (p = 0.007), was lower for BM compared with PB (p = 0.012), and was higher for ATT than for CLI (p = 0.020).

CONCLUSION

ATT regimen achieved a higher MR than CLI, although both arms had similar 5-year RFS.

Interphase fluorescence in situ hybridization with an IGH probe is important in the evaluation of patients with a clinical diagnosis of chronic lymphocytic leukaemia

Translocations involving IGH are common in some lymphoid malignancies but are believed to be rare in chronic lymphocytic leukaemia (CLL). To study the clinical utility of fluorescence in situ hybridization (FISH) for IGH translocations, we reviewed 1032 patients with a presumptive diagnosis of CLL. Seventy-six (7%) patients had IGH translocations. Pathology and clinical data were available for the 24 patients evaluated at the Mayo Clinic. Ten (42%) patients had IGH/cyclin D1 fusion and were diagnosed with mantle cell lymphoma (MCL). The immunophenotype was typical of MCL in three of these patients and atypical for MCL in seven patients. One patient had biclonal disease with typical MCL and CLL with IGH/BCL-2. Eleven (46%) patients had IGH/BCL-2 fusion including the patient with biclonal disease. Two of these patients had leukaemic phase follicular lymphoma and nine patients had CLL. The median progression-free survival of patients with CLL and IGH/BCL-2 translocation was 20.6 months. The two patients with IGH/BCL-3 fusion (one of these also had IGH/BCL-11a) had rapid disease progression. The IGH partner gene was not identified in two patients. We conclude that use of an IGH probe in FISH analysis of monoclonal B-cell lymphocytosis improves diagnostic precision and could have prognostic value in patients with CLL.

Cooperative Cytotoxicity of Proteasome Inhibitors and Tumor Necrosis Factor–Related Apoptosis-Inducing Ligand in Chemoresistant Bcl-2-Overexpressing Cells

PURPOSE

Bcl-2 overexpression is frequently detected in lymphoid malignancies, being associated with poor prognosis and reduced response to therapy. Here, we evaluated whether Bcl-2 overexpression affects the cytotoxic activity of proteasome inhibitors taken alone or in association with conventional anticancer drugs or tumor necrosis factor-related apoptosis-inducing ligand (TRAIL).

EXPERIMENTAL DESIGN

Jurkat cells engineered to overexpress Bcl-2 were treated with proteasome inhibitors (MG132, epoxomicin, and bortezomib), anticancer drugs (etoposide and doxorubicin), TRAIL, or combinations of these compounds. Cell death and loss of mitochondrial transmembrane potential were detected by flow cytometry. Cytosolic relocalization of cytochrome c and SMAC/Diablo, caspase cleavage, and Bcl-2 and Mcl-1 levels were determined by immunoblotting. Nuclear factor-kappaB inhibition was done by retroviral transduction with a dominant-negative mutant of IkappaBalpha.

RESULTS

Bcl-2 overexpression results in significant inhibition of apoptosis in response to proteasome inhibitors, antiblastics, and TRAIL. Addition of TRAIL to proteasome inhibitors results in a synergistic cytotoxic effect in Bcl-2-overexpressing cells, whereas this result is not reproduced by the combination of proteasome inhibitors with antiblastic drugs. Importantly, proteasome inhibitors plus TRAIL induce mitochondrial dysfunction irrespective of up-regulated Bcl-2. Bcl-2 cleavage to a fragment with putative proapoptotic activity and elimination of antiapoptotic Mcl-1 may both play a role in proteasome inhibitors-TRAIL cooperation. Conversely, nuclear factor-kappaB inhibition by proteasome inhibitors is per se insufficient to explain the observed synergy.

CONCLUSIONS

Combined proteasome inhibitors and TRAIL overcome the apoptotic threshold raised by Bcl-2 and may prove useful in the treatment of chemoresistant malignancies with up-regulated Bcl-2.

Lack of Bcl-2 expression in follicular lymphoma may be caused by mutations in the BCL2 gene or by absence of the t(14;18) translocation

Follicular lymphoma (FL), except grade 3B, is characterized by the chromosomal translocation t(14;18)(q32;q21), which results in over-expression of the Bcl-2 protein. Ten per-cent of all FLs, however, do not show Bcl-2 protein expression with standard immunohistochemistry using a monoclonal Bcl-2 antibody against residues 41-54 of the Bcl-2 protein. In this study, the biological background of 18 Bcl-2-negative FL cases grade I, II, or IIIa was investigated by immunohistochemical staining and western blot analysis with alternative antibodies. Bcl-2 protein was demonstrated in five of the 18 cases and all of these carried the t(14;18) translocation. Of the 13 cases that were Bcl-2 negative with alternative antibodies, 12 lacked the t(14;18) translocation. PCR and subsequent sequence analysis of cDNA demonstrated that three cases with a t(14;18) contained somatic mutations in the translocated BCL2 gene, resulting in amino acid replacements in the region of the epitope recognized by the antibody. In conclusion, the majority of Bcl-2-negative FL lack a t(14;18) but a significant subset of these tumours are false negative due to mutations in the BCL2 gene. These findings may have consequences for the use of Bcl-2 immunohistochemistry for diagnostic purposes.

Bcl-2 expression inversely correlates with tumour cell differentiation in medulloblastoma

Medulloblastoma (MB) is a cerebellar primitive neuroectodermal tumour that occurs predominantly in childhood. It can be mainly divided into classical and desmoplastic tumours, but differential diagnosis is often difficult. Patients' prognosis is poor and neuropathological markers that reliably predict outcome are still missing. In a series of 104 MBs including 80 tumours of the classical and 24 tumours of the desmoplastic variant we studied the number of apoptotic figures and the expression of the proto-oncogene bcl-2, an anti-apoptotic protein known to affect tumour cell proliferation. We observed a strong correlation between the expression of bcl-2 with patients' age (P < 0.001) as well as with the desmoplastic subtype (P < 0.001). Here, protein expression was found to be restricted to internodular, less differentiated, highly proliferative areas. In classical MB, bcl-2 was detected only in 23% of cases and was highly inversely correlated with the expression of synaptophysin (P < 0.001) indicating that bcl-2 is predominantly expressed by undifferentiated classical MB. With regard to prognosis the expression of bcl-2 tended to correlate with poor outcome in classical MB but not in desmoplastic MB, although not to a statistically significant extension (P = 0.06). On the other hand, a high number of apoptotic figures in the tumour tissue was found to indicate poor prognosis independent of the histological subtype (P < 0.05).

Autophagic and apoptotic features during programmed cell death in the fat body of the tobacco hornworm (Manduca sexta)

Two major pathways of programmed cell death (PCD)--the apoptotic and the autophagic cell death--were investigated in the decomposition process of the larval fat body during the 5th larval stage of Manduca sexta. Several basic aspects of apoptotic and autophagic cell death were analyzed by morphological and biochemical methods in order to disclose whether these mechanisms do have shared common regulatory steps. Morphological examination revealed the definite autophagic wave started on day 4 followed by DNA fragmentation as demonstrated by agarose gel electrophoresis and TUNEL assay. By the end of the wandering period the cells were filled with autophagic vacuoles and protein granules of heterophagic origin and the vast majority of the nuclei were TUNEL-positive. No evidence was found of other aspects of apoptosis, e.g. activation of executioner caspases. Close correlation was disclosed between the onset of autophagy and the nuclear accumulation of the ubiquitin-proteasome system.

Enhanced efficacy of therapy with antisense BCL-2 oligonucleotides plus anti-CD20 monoclonal antibody in scid mouse/human lymphoma xenografts

Monoclonal anti-CD20 antibody (rituximab) is active, but not curative, therapy for B-cell non-Hodgkin's lymphoma. BCL-2 is an antiapoptotic protein whose expression is dysregulated in most indolent B-cell malignancies. Antisense oligonucleotides (AS-ODNs) that down-regulate BCL-2 expression induce apoptosis and chemosensitize B-cell lymphoma cells. We hypothesized that BCL-2 down-regulation by AS-ODNs would sensitize cells to rituximab and improve therapeutic results. There is enhanced apoptosis and reduction in cell numbers when DoHH2 cells are treated in vitro with rituximab plus BCL-2 AS-ODNs, compared with either agent alone. There is little in vitro effect on WSU-FSCCL cells by rituximab, AS-ODNs that down-regulate BCL-2 by targeting the immunoglobulin portions of the BCL-2-immunoglobulin fusion molecule, or a combination of the two. The combination is more effective than either agent alone in clearing DoHH2 cells from ascites in scid mice. Combination therapy with AS-BCL-2-ODNs and rituximab significantly prolongs survival in both the DoHH2 and WSU-FSCCL models. With higher and repeated doses, this combination could be curative. We conclude that the combination of rituximab and antisense-mediated down-regulation of BCL-2 has enhanced activity against human lymphoma, prolongs survival, and could cure mice bearing human lymphoma. This merits investigation in clinical trials.

CD10 protein expression in tumor and stromal cells of malignant melanoma is associated with tumor progression

CD10 antigen is a 100-kDa-cell surface zinc metalloendopeptidase expressed in a variety of normal and neoplastic lymphoid and nonlymphoid tissues including melanomas. It was recently shown that metastatic melanomas express more CD10 than primary tumors. We evaluated CD10 expression in tumor and stromal cells in 70 biopsies with primary and 28 with metastatic malignant melanomas. Ki-67, Bcl-2, and Bax were also examined to investigate whether CD10 expression is associated with tumor proliferation index or factors of apoptosis. Formalin-fixed/paraffin-embedded tissues were studied by immunohistochemistry. More advanced primary tumors had higher CD10 expression in the tumor cells (r = 0.27, P = 0.03 for Clark levels and r = 0.29, P = 0.02 for Breslow) and higher Ki-67 proliferation fraction (r = 0.32, P = 0.007 for Clark levels and r = 0.32, P = 0.001 for Breslow). Similarly, CD10 expression in the intratumoral stromal cells was also higher in primary tumors with higher Clark level (P = 0.04, linear-by-linear association) and tumor thickness according to Breslow (r = 0.33, P = 0.01). The presence of CD10+ peritumoral stromal cell cuffs was also positively associated with tumor thickness according to Breslow (r = 0.27, P = 0.05). Also, expression of CD10 and Ki-67 were significantly higher in metastatic than in primary tumors (P = 0.01 and 0.02 respectively), but Bcl-2 expression was higher in primary melanomas (P = 0.02). We conclude that CD10 expression in malignant melanoma is associated with tumor progression.

Tracking the follicular lymphoma cells in flow cytometry: characterisation of a new useful antibody combination

OBJECTIVES

Follicular lymphoma (FL) is the most common adult non-Hodgkin's lymphoma. Diagnosis is based on morphology and can be confirmed by cytogenetic, flow cytometry (FCM) or molecular studies. Despite all these complementary approaches, diagnosis sometimes remains difficult. The purpose of the present work was to characterise the expression of new specific follicular cells markers which allows us to target specifically the abnormal FL cell population in FCM.

METHODS

A total of 153 samples from healthy subjects and from patients with chronic B-cell lymphoproliferative disorders were analysed by FCM in the same conditions for purpose of comparison.

RESULTS

We showed that CD44 is weakly expressed in FL cells compared with peripheral blood mononuclear cell from normal blood donors and others cells from B lymphoproliferative diseases. We nevertheless observed bone marrow samples where some immature B-cell population express CD44 with lower fluorescence intensity. Therefore, we developed a double antibody combination, using CD44 and CD38, which allowed us to separate the normal immature cells from the pathological population using FCM.

CONCLUSION

This new phenotypic approach offers an accurate (sensitivity and specificity of 93% and 96%, respectively), fast and low sample consuming method for the diagnosis of FL.

Fenretinide enhances rituximab-induced cytotoxicity against B-cell lymphoma xenografts through a caspase-dependent mechanism

The anti-CD20 monoclonal antibody rituximab induces remission in 40% to 60% of patients with indolent B-cell lymphoma, but virtually all patients have relapses. We evaluated the efficacy of concurrent administration of another biologic agent, N-(4-hydroxyphenyl) retinamide (4HPR, fenretinide) with rituximab against a variety of human B-cell lymphoma cell lines (Ramos, DHL-4, and FL-18) in vivo. Concurrent 4HPR and rituximab administration prevented tumor progression of lymphoma-bearing mice in a minimal disease model (rituximab + 4HPR, 100% progression free; rituximab alone, 37.5% progression free, P = .01; 4HPR alone, 12.5% progression free, P &lt; .01; controls, 0% progression free, P &lt; .01). Combinations of 4HPR + rituximab exceeded the predicted 50% additive rate of disease control from each agent alone (P = .038). Administering 4HPR and rituximab to mice with established tumors induced complete responses (CRs) in 80% of animals compared with 20% to 40% CRs using either agent alone (P = .07), resulting in significantly improved survival. Tumors harvested from 4HPR + rituximab-treated mice displayed elevated caspase activation compared with untreated controls (P = .02). Adding a broad-spectrum caspase inhibitor in vivo fully abrogated the antitumor effects of 4HPR + rituximab (P = .05). These results establish the efficacy of 4HPR/rituximab combinations, confirm their caspase-mediated mechanism of action, and offer the potential for disease control with minimal toxicity for patients with B-cell malignancies. (Blood. 2004;103:3516-3520)

Molecular response of follicular lymphoma to cyclophosphamide, doxorubicin, vincristine, prednisone C(H)OP or COP-based therapy as measured by polymerase chain reaction evidence of translocation (14;18)(q32;q21)

PURPOSE

Existing data suggest that conventional C(H)OP (cyclophosphamide, doxorubicin, vincristine, prednisone) regimen may not be intensive enough to achieve molecular response, as measured by polymerase chain reaction (PCR) evidence of translocation (14;18)(q32:q21) for follicular lymphoma. This study was undertaken to study the molecular response rate of follicular lymphoma to C(H)OP-based therapy and to analyze prognostic factors for molecular response.

PATIENTS AND METHODS

Twenty patients with pretreatment PCR evidence of t(14;18)(q32; q21) and at least one posttreatment PCR analysis after the initiation of the treatment with C(H)OP with or without radiation therapy constituted the basis for this analysis. The random effects logistic model was used to analyze the data. The following factors were investigated for their relationship to molecular response: gender, age, beta2-microglobulin, use of radiation therapy, Ann Arbor stage, and international Prognostic Index for malignant lymphoma.

RESULTS

Median follow-up was 56 months (range, 23-153 months). A total of 135 PCR results were available, 33 from bone marrow and 102 from peripheral blood. Overall, there was a clear and steady decreasing trend toward loss of PCR positivity with increasing time aftertreatment. By univariate analysis, stage > or = 3, stage = 4, International Prognostic Index > or = 2, and no radiation therapy were adverse factors for molecular response. On multivariate analysis, Ann Arbor stage IV and no radiation therapy were independent risk factors for PCR positivity, both for the peripheral blood data analyzed alone and for all data combined.

DISCUSSION

It is possible to achieve molecular response with C(H)OP with or without radiation therapy in patients with follicular lymphoma. Response rate depends on the Ann Arbor stage and radiation therapy.

Divergence of Genbank and human tumor Bcl-2 sequences and implications for binding affinity to key apoptotic proteins

Heterodimerization of antiapoptotic and pro-apoptotic Bcl-2 family of proteins provides an important mechanism for apoptosis regulation. Knowledge about key amino acids in the binding groove of native Bcl-2 contributing to this interaction will greatly facilitate the design of Bcl-2-specific inhibitors. There are two different Bcl-2 sequences, M13994 and M14745, in Genbank. Chimeric proteins Bcl-2(1) and Bcl-2(2) derived from the above sequences, although similar in structure, showed different binding affinities to Bak and Bad BH3 peptides (Petros et al., 2001). In this study, we show that the Bcl-2(1) sequence in normal and tumor human tissue samples differs from M13994 and M14745, and contains P59, T96, R110, S117 and G237. The actual sequence in the binding pocket matches the Bcl-2-Ig fusion sequence X06487, originally identified in a t(14:18) translocation of the Bcl-2 gene, associated with follicular lymphoma. The possible effects of the observed amino acid differences compared to M13994 and M14745 were investigated by combining structural data with fluorescence anisotropy. G110R substitution confers on Bcl-2(1) substantially increased binding affinity to Bak, Bad and Bax BH3 peptides, demonstrating that R110 is a key contributor to the BH3 binding affinity of Bcl-2. Although NMR structure did not predict R110 involvement in binding to these BH3 peptides, fluorescence anisotropy data clearly points to a critical role for this residue in binding to pro-apoptotic Bcl-2 family members.