Pharmacokinetic profile and first preliminary clinical evaluation of bendamustine in Taiwanese patients with heavily pretreated indolent B‐cell non‐Hodgkin lymphoma and mantle cell lymphoma

Prior studies found bendamustine is efficacious in patients with indolent B‐cell non‐Hodgkin lymphoma (NHL). To date, no studies have reported the efficacy of bendamustine in a Chinese population. This multicentre phase II trial evaluated the pharmacokinetics (PK), safety and efficacy of bendamustine monotherapy in Chinese patients in Taiwan with pretreated indolent B‐cell NHL or mantle cell lymphoma (MCL). For PK assessments, patients were randomized (n = 16; 11 with indolent B‐cell NHL and five with MCL) to 90 or 120 mg/m² of bendamustine for the first cycle. Plasma levels of bendamustine and its two metabolites were analyzed. For efficacy and safety evaluations, bendamustine 120 mg/m² was given to all patients every 3 weeks starting at cycle 2 for a minimum of a total of six cycles. The median age of patients was 61.7 years, and the majority were men (75%). The median number of prior treatments was 4 (range, 1–9 regimens), and all patients were previously treated with rituximab. Bendamustine plasma concentration peaked near the end of infusion and was rapidly eliminated with a mean elimination half‐life (t_1/2) of 0.67–0.8 h. Of the evaluable patients (n = 14), the overall response rate was 78.6%, including 7.2% of patients having a complete response. Mean progression‐free survival was 27.5 weeks. The most common grade 3–4 adverse events were leucopenia (56.3%), neutropenia (56.3%) and thrombocytopenia (25%). In conclusion, bendamustine was efficacious and well tolerated in Taiwanese patients with indolent NHL and MCL with a similar PK profile to that of other populations. Copyright © 2014 John Wiley & Sons, Ltd.     

An overlapping case of in situ mantle cell neoplasia and leukemic non-nodal mantle cell lymphoma

In situ mantle cell neoplasia (isMCN) and leukemic non-nodal mantle cell lymphoma (nnMCL) are classified as an indolent subtype of mantle cell lymphoma (MCL). The tumor cells of isMCN are restricted to the inner layer of the lymphoid tissue mantle zone, exhibiting an in situ pattern histologically. On the other hand, nnMCL is distributed in the peripheral blood, bone marrow and sometimes the spleen, but lymphadenopathy or systemic organ involvement is rare. We report a case of isMCN in a submandibular lymph node resected from a 65-year-old Japanese male. The tumor cells were positive for cyclin D1 (CCND1) and SOX11 expression, and were restricted to the mantle zone area of the lymph node. However, tumor cells were also detected in the stomach mucosa, bone marrow tissue and peripheral blood, suggesting nnMCL. isMCN and nnMCL may have a partly overlapping disease spectrum, although the correlation between these two subtypes has not been well described. This present case demonstrated characteristics overlapping between isMCN and nnMCL.     

U-2940, a human B-cell line derived from a diffuse large cell lymphoma sequential to Hodgkin lymphoma

Several patterns of association between Hodgkin and non-Hodgkin lymphomas are recognized, some of which support a common cellular origin or shared transformation events for both malignancies. We describe the U-2940 cell line derived from a diffuse large B-cell lymphoma with some features consistent with mediastinal large B-cell lymphoma, clinically apparent 1 month after the initial course of chemotherapy for Hodgkin's disease, fulfilling the criteria for composite malignancies. U-2940 cells display a mature B phenotype with hypermutated IgH rearrangement typical of germinal/postgerminal center origin. The cell line is negative for Epstein-Barr virus and no evidence of t(14;18) was found. U-2940 cells display multiple chromosomal rearrangements similar to recurrent aberrations described in both Hodgkin and non-Hodgkin lymphomas, also partially shared by U-2932 derived from a B-cell lymphoma sequential to Hodgkin's disease. The original large B-cell lymphoma and the U-2940 cell line bear microsatellite instability, an abnormality associated with particular subtypes of non-Hodgkin lymphomas and found in tissues involved by Hodgkin lymphoma. Therefore, U-2940 cells bear several features known to occur in Hodgkin and in non-Hodgkin lymphomas, leading to the assumption that this cell line may constitute a useful tool to address elective pathways of lymphomagenesis and eventually the Hodgkin and non-Hodgkin lymphoma association.     

Characterization of a mantle cell lymphoma cell line resistant to the Chk1 inhibitor PF-00477736

Mantle cell lymphoma (MCL) is an aggressive B-cell lymphoma characterized by the chromosomal translocation t(11;14) that leads to constitutive expression of cyclin D1, a master regulator of the G1-S phase. Chk1 inhibitors have been recently shown to be strongly effective as single agents in MCL. To investigate molecular mechanisms at the basis of Chk1 inhibitor activity, a MCL cell line resistant to the Chk1 inhibitor PF-00477736 (JEKO-1 R) was obtained and characterized. The JEKO-1 R cell line was cross resistant to another Chk1 inhibitor (AZD-7762) and to the Wee1 inhibitor MK-1775. It displayed a shorter doubling time than parental cell line, likely due to a faster S phase. Cyclin D1 expression levels were decreased in resistant cell line and its re-overexpression partially re-established PF-00477736 sensitivity. Gene expression profiling showed an enrichment in gene sets involved in pro-survival pathways in JEKO-1 R. Dasatinib treatment partly restored PF-00477736 sensitivity in resistant cells suggesting that the pharmacological interference of pro-survival pathways can overcome the resistance to Chk1 inhibitors. These data further corroborate the involvement of the t(11;14) in cellular sensitivity to Chk1 inhibitors, fostering the clinical testing of Chk1 inhibitors as single agents in MCL.     

Abemaciclib,a CDK4/6 inhibitor,exerts preclinical activity against aggressive germinal center‐derived B‐cell lymphomas

The revised WHO classification newly defined the entities “High‐grade B‐cell lymphoma with MYC and BCL2, and/or BCL6 rearrangements (HGBL‐DH/TH)” and “HGBL, NOS.” Standard immunochemotherapy for diffuse large B‐cell lymphoma (DLBCL), R‐CHOP, is insufficient for HGBL patients, and there are currently no optimized therapeutic regimens for HGBL. We previously reported that CCND3, which encodes cyclin D3, harbored high mutation rates in Burkitt lymphoma (BL), HGBL and a subset of DLBCL. Furthermore, the knockdown of cyclin D3 expression was toxic to germinal center (GC)‐derived B‐cell lymphomas. Thus, the fundamental function of cyclin D3 is important for the pathogenesis of GC‐derived B‐cell lymphoma. We herein used two structurally different CDK4/6 inhibitors, palbociclib and abemaciclib, and examined their suppressive effects on cell proliferation and their ability to induce apoptosis in various aggressive B‐cell lymphoma cell lines. The results obtained demonstrated that abemaciclib more strongly suppressed cell proliferation and induced apoptosis in GC‐derived B‐cell lymphoma cell lines than the control, but only slightly inhibited those features in activated B‐cell (ABC)‐like DLBCL cell lines. Palbociclib exerted partial or incomplete effects compared with the control and the effect was intermediate between abemaciclib and the control. Moreover, the effects of abemaciclib appeared to depend on cyclin D3 expression levels based on the results of the expression analysis of primary aggressive B‐cell lymphoma samples. Therefore, abemaciclib has potential as a therapeutic agent for aggressive GC‐derived B‐cell lymphomas.     

Bendamustine is effective therapy in patients with rituximab‐refractory,indolent B‐cell non‐Hodgkin lymphoma

BACKGROUND:

Bendamustine hydrochloride is a novel alkylating agent. In this multicenter study, the authors evaluated the efficacy and toxicity of single‐agent bendamustine in patients with rituximab‐refractory, indolent B‐cell lymphoma.

METHODS:

Eligible patients (N = 100, ages 31‐84 years) received bendamustine at a dose of 120 mg/m² by intravenous infusion on Days 1 and 2 every 21 days for 6 to 8 cycles. Histologies included follicular (62%), small lymphocytic (21%), and marginal zone (16%) lymphomas. Patients had received a median of 2 previous regimens (range, 0‐6 previous regimens), and 36%were refractory to their most recent chemotherapy regimen. Primary endpoints included overall response rate (ORR) and duration of response (DOR). Secondary endpoints were safety and progression‐free survival (PFS).

RESULTS:

An ORR of 75% (a 14% complete response rate, a 3% unconfirmed complete response rate, and a 58% partial response rate) was observed. The median DOR was 9.2 months, and median PFS was 9.3 months. Six deaths were considered to be possibly treatment related. Grade 3 or 4 (determined using National Cancer Institute Common Toxicity Criteria [version 3.0.19]. reversible hematologic toxicities included neutropenia (61%), thrombocytopenia (25%), and anemia (10%). The most frequent nonhematologic adverse events (any grade) included nausea (77%), infection (69%), fatigue (64%), diarrhea (42%), vomiting (40%), pyrexia (36%), constipation (31%), and anorexia (24%).

CONCLUSIONS:

Single‐agent bendamustine produced a high rate of objective responses with acceptable toxicity in patients with recurrent, rituximab‐refractory indolent B‐cell lymphoma. Cancer 2010. © 2010 American Cancer Society.     

EBV primary infection in childhood and its relation to B‐cell lymphoma development: A mini‐review from a developing region

In most underdeveloped countries, the initial contact with Epstein Barr virus (EBV) usually happens in the first decade of life and results in an asymptomatic infection, whereas in developed areas, primary infection in adolescence or adulthood is accompanied by infectious mononucleosis in 50% cases. Although it is generally a harmless passenger, in some individuals, it is associated with B‐cell lymphoma. In Argentina, EBV primary infection shows the classical pattern observed in developing populations, given that nearly 70% of patients are seropositive by the age of 2 years. However, EBV association with pediatric Hodgkin and Burkitt lymphoma resembles that observed in developed regions. Concerning diffuse large B‐cell lymphoma, our series demonstrated higher EBV association than other adult ones from either developed or underdeveloped countries. Interestingly, the early EBV primary infection observed, characteristic of an underdeveloped population, together with the statistically significant EBV association with patients ≤10 years old demonstrated in all types of lymphoma studied, suggest a relationship between low age of EBV seroconversion and B‐cell lymphoma development risk.     

Clinical development of anti‐CD19 chimeric antigen receptor T‐cell therapy for B‐cell non‐Hodgkin lymphoma

B‐cell non‐Hodgkin lymphoma (B‐NHL) is the most frequent hematological malignancy. Although refined chemotherapy regimens and several new therapeutics including rituximab, a chimeric anti‐CD20 monoclonal antibody, have improved its prognosis in recent decades, there are still a substantial number of patients with chemorefractory B‐NHL. Anti‐CD19 chimeric antigen receptor (CAR) T‐cell therapy is expected to be an effective adoptive cell treatment and has the potential to overcome the chemorefractoriness of B‐cell leukemia and lymphoma. Recently, several clinical trials have shown remarkable efficacy of anti‐CD19 CAR T‐cell therapy, not only in B‐acute lymphoblastic leukemia but also in B‐NHL. Nonetheless, there are several challenges to overcome before introduction into clinical practice, such as: (i) further refinement of the manufacturing process, (ii) further improvement of efficacy, (iii) finding the optimal infusion cell dose, (iv) optimization of lymphocyte‐depleting chemotherapy, (v) identification of the best CAR structure, and (vi) optimization of toxicity management including cytokine release syndrome, neurologic toxicity, and on‐target off‐tumor toxicity. Several ways to solve these problems are currently under study. In this review, we describe the updated clinical data regarding anti‐CD19 CAR T‐cell therapy, with a focus on B‐NHL, and discuss the clinical implications and perspectives of CAR T‐cell therapy.     

Presence of autoimmune disease affects not only risk but also survival in patients with B‐cell non‐Hodgkin lymphoma

Although autoimmune diseases (AIDs) are known to predispose to non‐Hodgkin lymphoma (NHL), their association with NHL prognosis has rarely been investigated. We examined associations between autoimmunity and B‐cell NHL onset by comparing AID history (determined by self‐report and medication review and supplemented by chart review where possible) among 435 adult B‐NHL patients in Hadassah‐Hebrew University Medical Center, diagnosed 2009‐2014, and 414 age‐and‐sex frequency‐matched controls. We examined AIDs as a whole, B‐ and T‐cell–mediated AIDs, and autoimmune thyroid diseases. Among cases, we used Kaplan‐Meier and Cox regression models to assess the association of AID with overall survival and relapse‐free survival, adjusting for prognostically important patient and disease characteristics such as Ki67% staining, International Prognostic Index, rituximab treatment, and histological subgroup. Autoimmune diseases were associated with B‐NHL (odds ratio [OR] = 1.95; 95% confidence interval (CI), 1.31‐2.92), especially AIDs mediated by B‐cell activation (OR = 5.20; CI, 1.90‐14.3), which were particularly associated with marginal zone lymphoma (OR = 19.3; CI, 4.59‐80.9). We found that time to relapse for all B‐NHL patients with AIDs was significantly shorter (mean of 49.21 mo [±3.22]) than among patients without AID (mean of 59.74 mo [±1.62]), adjusted hazard ratio [HR_adj] = 1.69 (CI, 1.03‐2.79). Specifically, in patients with diffuse large B‐cell lymphoma, of whom 91.8% had received rituximab, a history of B‐cell–mediated AIDs was associated with shorter relapse‐free survival and overall survival, HR_adj = 8.34 (CI, 3.01‐23.1) and HR_adj = 3.83 (CI, 1.20‐12.3), respectively. Beyond confirming the well‐known association between AIDs and B‐NHL, we found that AID is an adverse prognostic factor in B‐cell lymphoma, associated with a shortened time to relapse, suggesting that there are specific therapeutic challenges in the subgroup of patients suffering from both these diseases. Further work is required to address mechanisms of resistance to standard treatment in the setting of AID‐associated B‐NHL. In the era of immunotherapy, these findings have particular relevance.     

Classifying B‐cell non‐Hodgkin lymphoma by using MIB‐1 proliferative index in fine‐needle aspirates

BACKGROUND:

MIB‐1 proliferation index (PI) has proven helpful for diagnosis and prognosis in non‐Hodgkin lymphomas (NHLs). However, validated cutoff values for use in fine‐needle aspiration (FNA) samples are not available. We investigated MIB‐1 immunocytochemistry as an ancillary technique for stratifying NHL and attempted to establish PI cutpoints in cytologic samples.

METHODS:

B‐cell NHL FNA cases with available cytospins (CS) MIB‐1 immunocytochemistry results were included. Demographic, molecular, immunophenotyping and MIB‐1 PI data were collected from cytologic reports. Cases were subtyped according to the current World Health Organization classification and separated into indolent, aggressive, and highly aggressive groups. Statistical analysis was performed with pairwise Wilcoxon rank sum test and linear discriminant analysis to suggest appropriate PI cutpoints.

RESULTS:

Ninety‐one NHL cases were subdivided in 56 (61.5%) indolent, 30 (33%) aggressive, and 5 (5.5%) highly aggressive lymphomas. The 3 groups had significantly different MIB‐1 PIs from each other. Cutpoints were established for separating indolent (<38%), aggressive (≥38% to ≤80.1%) and highly aggressive (>80.1%). The groups were adequately predicted in 76 cases (83.5%) using the cutpoints and 15 cases showed discrepant PIs.

CONCLUSIONS:

MIB‐1 immunohistochemistry on CS can help to stratify B‐cell NHL and showed a significant increase in PI with tumor aggressiveness. Six misclassified cases had PIs close to the cutpoints. Discrepant MIB‐1 PIs were related to dilution of positive cells by non‐neoplastic lymphocytes and to the overlapping continuum of features between diffuse large B‐cell lymphoma and Burkitt lymphoma. Validation of our approach in an unrelated, prospective dataset is required. Cancer (Cancer Cytopathol) 2010. © 2010 American Cancer Society.     

Quantitative monitoring of cyclin D1 expression: a molecular marker for minimal residual disease monitoring and a predictor of the disease outcome in patients with mantle cell lymphoma

In mantle cell lymphoma (MCL), minimal residual disease (MRD) is an indicator of the disease outcome. Quantitative methods used so far do not provide a suitable molecular marker in 30-70% patients with MCL (depending on the technique used). We tested cyclin D1 as a marker for quantitative MRD monitoring. The real-time PCR of cyclin D1 mRNA was performed in 144 bone marrow (BM) specimens including 95 BMs from MCL patients, 39 BMs from patients with other B-cell non-Hodgkin's lymphomas and 10 BMs from healthy volunteer donors. In 73 BMs obtained from 20 MCL patients we examined the cyclin D1 level during the treatment and follow-up period. We detected a cyclin D1 overexpression exclusively in BMs infiltrated with MCL, including minimal residual infiltration. Dynamics of cyclin D1 correlated with the patient's clinical status in 69/73 BMs. Individual monitoring of patients during the disease course showed cyclin D1 quantitative changes accompanying either the disease relapse or a successful treatment response or the disease-free survival (remission) and it showed a predictive significance. Cyclin D1 detection is a promising approach for the quantitative MRD monitoring in MCL patients, and the individual monitoring of the cyclin D1 dynamics represents a suitable indicator of the disease course.     

Primary diffuse large B‐cell lymphoma of the tonsil

BACKGROUND: The purpose was to evaluate the prognostic factors and treatment outcome of Indian patients with primary diffuse large B-cell lymphoma (DLBCL) of the tonsil treated at a single institution. METHODS: In all, 121 patients with DLBCL of the tonsil, treated at the Tata Memorial Hospital, Mumbai, India, from January 1990 to December 2002, were included. The median age was 45 years and the majority of patients (68%) were males. Systemic symptoms were present in 12% of patients; 28% presented with stage I and 67% had stage II disease. Treatment consisted of a combination of chemotherapy (CTh) and radiotherapy (RT) for the majority of patients (69.4%). Among those receiving RT, 64% received an RT dose of > or =45 Gy. RESULTS: After a median follow-up of 62 months, disease-free survival (DFS) and overall survival (OS) were 66.4% and 81.6%, respectively. Significant prognostic factors included: WHO performance score > or =2 (OS: 72.1% vs 95.6%, P = .016), bulky tumors (OS: 68.5% vs 86.9%, P = .001), presence of B-symptoms (OS: 36.7% vs 79.6%, P < .001), and Ann Arbor stage. On multivariate analysis; WHO performance score > or =2 (hazard ratio [HR], 4.27; 95% confidence interval [CI], 1.20-15.12), and B symptoms (HR, 6.27; 95% CI, 2.38-16.48), retained statistical significance. CTh + RT resulted in a significantly better outcome than those treated with CTh alone (OS: 85.7% vs 70.7%, P = .008). The complete response (P = .053), DFS (P = .039), and OS (P = .014) rates were significantly better for patients receiving an RT dose > or =45 Gy. CONCLUSIONS: Tumor bulk, WHO performance score, the presence of B symptoms, and Ann Arbor stage significantly influence outcome. A combined modality treatment, consisting of CTh and RT (with an RT dose of > or =45 Gy), results in a satisfactory outcome in patients with this uncommon neoplasm.     

BCL2 mutation spectrum in B‐cell non‐Hodgkin lymphomas and patterns associated with evolution of follicular lymphoma

BCL2 is a target of somatic hypermutation in t(14;18) positive and also in a small fraction of t(14;18) negative diffuse large B‐cell lymphoma (DLBCL), suggesting an aberrant role of somatic hypermutation (ASHM). To elucidate the prevalence of BCL2 mutations in lymphomas other than DLBCL, we Sanger‐sequenced the hypermutable region of the BCL2 gene in a panel of 69 mature B‐cell lymphomas, including Richter's syndrome DLBCL, marginal‐zone lymphomas, post‐transplant lymphoproliferative disorders, HIV‐associated and common‐variable immunodeficiency‐associated DLBCL, all known to harbour ASHM‐dependent mutations in other genes, as well as 16 t(14,18) negative and 21 t(14;18) positive follicular lymphomas (FLs). We also investigated the pattern of BCL2 mutations in longitudinal samples from 10 FL patients relapsing to FL or transforming to DLBCL (tFL). By direct sequencing, we found clonally represented BCL2 mutations in 2/16 (13%) of t(14;18) negative FLs, 2/16 (13%) HIV‐DLBCLs, 1/9 (11%) of Richter's syndrome DLBCL, 1/17 (6%) of post‐transplant lymphoproliferative disorders and 1/2 (50%) common‐variable immunodeficiency‐associated DLBCL. The proportion of mutated cases was significantly lower than in FLs carrying the t(14;18) translocation (15/21, 71%). However, the absence of t(14;18) by FISH or PCR and the molecular features of the mutations strongly suggest that BCL2 represents an additional target of ASHM in these entities. Analysis of the BCL2 mutation pattern in clonally related FL/FL and FL/tFL samples revealed two distinct scenarios of genomic evolution: (i) direct evolution from the antecedent FL clone, with few novel clonal mutations acquired by the tFL major clone, and (ii) evolution from a common mutated long‐lived progenitor cell, which subsequently acquired distinct mutations in the FL and in the relapsed or transformed counterpart. Copyright © 2014 John Wiley & Sons, Ltd.     

Serum beta‐2 microglobulin as a prognostic biomarker in patients with mantle cell lymphoma

Although serum beta‐2 microglobulin (B2M) has been suggested as a prognostic factor for mantle cell lymphoma (MCL), additional data are necessary to confirm its role. Between November 2005 and July 2014, a total of 52 patients with MCL were identified from the database of Asan Medical Center, Seoul, Korea. Pretreatment serum B2M information was available in 50 patients (96%). Overall survival (OS) was compared according to the serum B2M level with a cut‐off value of 2.5 mg/L. The median MCL international prognostic index (MIPI) score was 5.84 (range 4.72–7.80), and the median biologic MIPI (MIPI‐b) score was 6.27 (4.93–8.47). Pretreatment serum B2M was elevated in 30 patients (60%) and was significantly related to advanced stage (p = 0.02) and high MIPI (p = 0.03) and MIPI‐b (p = 0.03) scores. With median follow‐up duration of 29.8 months (range 0.8–87.0 months), the median OS was 56.2 months [95% confidence interval (CI) 36.6‐75.9 months] in all patients, and serum B2M was significantly associated with OS (p = 0.001). In multivariate analyses adjusted for MIPI or MIPI‐b scores and rituximab, elevated serum B2M was significantly associated with poor OS (when adjusting MIPI, hazard ratio = 26.4, 95% CI 2.9–241.3, p = 0.004; when adjusting MIPI‐b, hazard ratio = 20.1, 95% CI 2.4–170.1, p = 0.006). Thus, pretreatment serum B2M may be an independent and significant prognostic factor in patients with MCL. Copyright © 2015 John Wiley & Sons, Ltd.     

Concomitant high expression of Toll‐like receptor (TLR) and B‐cell receptor (BCR) signalling molecules has clinical implications in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive disease with frequent relapse. Targeted therapies against B‐cell receptor (BCR) molecules have demonstrated improved outcomes in relapsed cases. However, clinical responses are slow and selective, with failure to attain complete remission in a significant subset of patients. Complex interaction of BCR signal transduction with toll‐like receptor (TLR) and other pathways in MCL remains unknown, thus averting progress in development of targeted therapies. We have performed detailed digital quantification of BCR/TLR signalling molecules and their effector pathways in a cohort (n = 81) of MCL patients and correlated these data with overall survival. Hierarchical clustering model based on BCR/TLR genes revealed two distinct (BCR^high and BCR^low) subsets of patients (n = 32; 40%) with significant differences in expression (>1.5‐fold change; p < 0.05). Higher levels of BTK/SYK/BLNK/CARD11/PLCG signalosome and lower expression of MALT1/BCL10 genes suggested tonic pattern of BCR activation. Amplified expression of TLR6/TLR7/TLR9 was noted in concert with hyper‐responsiveness of BCR machinery. MYD88, a key TLR adaptor molecule, was not upregulated in any of these clusters, which may suggest a ‘cross‐talk’ between BCR and TLR pathways. In sync with BCR/TLR signalling, we recorded significantly enhanced expression of genes associated with NF‐kB pathway in BCR^high subset of MCL patients. On univariate analysis, the BCR^high patients showed a trend towards inferior clinical response to a standardized treatment protocol, compared with the BCR^low group (log rank, p = 0.043). In conclusion, we have identified hyperactive BCR/TLR signalling pathways and their effector downstream targets in a subset of MCL patients and associated it with poor clinical outcomes. Our study provides quantitative evidence at RNA expression level of possible concomitant collaboration between TLR and BCR signalling molecules in MCL. These data will provide further insights for future functional studies and, hence, development of targeted therapies for MCL patients. Copyright © 2015 John Wiley & Sons, Ltd.     

Burkitt lymphoma versus diffuse large B‐cell lymphoma: a practical approach

Burkitt Lymphoma (BL) is listed in the World Health Organization (WHO) classification of lymphoid tumours as an ‘aggressive B‐cell non‐Hodgkin's lymphoma’, characterized by a high degree of proliferation of the malignant cells and deregulation of the c‐MYC gene. The main diagnostic challenge in BL is to distinguish it from diffuse large B‐cell lymphoma (DLBCL). While in children BL and DLBCL types probably do not differ clinically, and the differential diagnosis between BL and DLBCL may theoretically appear clear‐cut, in adults daily practice shows the existence of cases that have morphological features, immunophenotypic and cytogenetics intermediate between DLBCL and BL, and cannot be classified with certainty in these categories. Distinguishing between BL and DLBCL is critical, as the two diseases require different management. This review summarizes the current practical approach, including the use of a large panel of antibodies, and cytogenetic and molecular diagnostic techniques, to distinguish between BL, DLBCL and the provisional category of ‘B‐cell lymphoma, unclassifiable, with features intermediate between diffuse large B‐cell lymphoma and Burkitt lymphoma’, now listed in the updated WHO classification. Copyright © 2009 John Wiley & Sons, Ltd.     

Immunotherapy of B‐cell non‐Hodgkin lymphoma by targeting the chemokine receptor CXCR5 in a preclinical mouse model

Bispecific antibodies are promising agents for immunotherapy. Here, we describe a quadroma‐based trifunctional bispecific antibody binding the chemokine receptor CXCR5 and the T‐cell antigen CD3 that efficiently prevents tumor growth in a mouse B‐cell lymphoma model. CXCR5 regulates the tissue homeostasis of mature B cells and is highly expressed on B‐cell non‐Hodgkin and lymphocyte‐predominant Hodgkin lymphoma, as well as on a subset of CD4⁺ T cells known as follicular T‐helper cells. In vitro, the bispecific CXCR5::CD3 antibody efficiently recruited effector T cells to CXCR5 expressing B cells and induced a co‐stimulation‐independent activation of CD8⁺ and CD4⁺ T cells as demonstrated by the de novo expression of CD25 and CD69, and secretion of the cytokines IFN‐γ, TNF‐α, IL‐6 and IL‐10 by peripheral blood mononuclear cells. Notably, at low antibody concentrations, CXCR5::CD3 displayed a significantly higher cytotoxic activity against autologous B cells than its parental antibodies or rituximab. In vivo imaging revealed that CXCR5::CD3 and its parental CXCR5 antibody efficiently prevent tumor growth in a xenograft model of B‐cell lymphoma in mice and prolong their survival. Taken together, our results identify CXCR5 as a promising target for antibody‐based therapies in the treatment of B‐cell malignancies.