B‐cell lymphoma,unclassifiable, with features intermediate between diffuse large B‐cell lymphoma and burkitt lymphoma: study of 39 cases

B‐cell lymphoma, unclassifiable (B‐UCL), with features intermediate between diffuse large B‐cell lymphoma and Burkitt lymphoma, is a poorly characterized entity. Therefore, we investigated cases of B‐UCL treated by the Nebraska Lymphoma Study Group (NLSG). We searched the NLSG registry for years 1985–2010 for cases of B‐UCL. Immunohistochemical stains and fluorescence in situ hybridization studies for MYC, BCL2 and BCL6 gene rearrangements were performed. Among the 39 cases studied, 54% were male and 46% were female, with a median age of 69 years. The majority of patients presented with advanced‐stage disease (62%) and had high (3–5) International Prognostic Index (IPI) scores (54%). The median overall survival (OS) was only 9 months and the 5‐year OS was 30%. Patients with low IPI scores (0–2) had a better survival than those with high scores (3–5). The cases were genetically heterogeneous and included 11 ‘double‐hit’ lymphomas with rearrangements of both MYC and BCL2 or BCL6. None of the immunohistochemical or genetic features was predictive of survival. This B‐cell lymphoma is a morphologically‐recognizable entity with a spectrum of genetic abnormalities. New and better treatments are needed for this aggressive lymphoma.     

Pro‐apoptotic TP53 homolog TAp63 is repressed via epigenetic silencing and B‐cell receptor signalling in chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia (CLL) is an accumulative disorder marked by deficient apoptosis. The TP53 homolog TAp63 promotes apoptosis and chemosensitivity in solid tumours and its deregulation may contribute to CLL cell survival. We found that TAp63α was the most prevalent TP63 isoform in CLL. Compared to healthy B cells, TAp63 mRNA was repressed in 55·7% of CLL samples. TP63 promoter methylation was high in CLL and inversely correlated with TP63 protein expression in B‐cell lymphoma cell lines. siRNA‐mediated knockdown of TP63 resulted in partial protection from spontaneous apoptosis accompanied by reductions in PMAIP1 (NOXA), BBC3 (PUMA), and BAX mRNA in CLL cells and increased proliferation of Raji lymphoma cells. TAp63 mRNA levels were higher in CLL with unmutated IGHV. B‐cell receptor (BCR) engagement led to repression of TP63 mRNA expression in malignant B cells, while pharmacological inhibition of BCR signalling prevented TP63 downregulation. MIR21, known to target TAp63, correlated inversely with TAp63 expression in CLL, and BCR‐mediated downregulation of TP63 was accompanied by MIR21 upregulation in most CLL samples. Our data illustrate the pro‐apoptotic function of TP63, provide insights into the mechanisms of BCR‐targeting agents, and establish a rationale for designing novel approaches to induce TP63 in CLL and B‐cell lymphoma.     

MYC and BCL2 protein expression predicts survival in patients with diffuse large B‐cell lymphoma treated with rituximab

Diffuse large B‐cell lymphoma (DLBCL) is a heterogeneous disease and “double‐hit” DLBCL, with both MYC and BCL2 translocations has a poor prognosis. In this study, we investigated whether MYC and BCL2 protein expression in tissue would predict survival in DLBCL. The study included 106 cases of de novo DLBCL treated with rituximab and cyclophosphamide, doxorubicin, vincristine and prednisone (R‐CHOP) or CHOP‐like regimens. The results were validated on an independent cohort of 205 DLBCL patients. Patients with low expression of BCL2 (≤30%) and MYC (≤50%) had the best prognosis, whereas those with high BCL2 (>30%) and MYC (>50%) had the worst outcome. In multivariate analysis, the combination of the BCL2 and MYC was an independent predictor of overall survival (OS) and event‐free survival (EFS) (P = 0·015 and P = 0·005, respectively). The risk of death was nine times greater for patients with high BCL2 and MYC compared to those with low expression. High BCL2 and MYC was a strong predictor of poor OS (P < 0·001) and EFS (P = 0·0017) in patients with the germinal centre B‐cell (GCB) type, but not in the non‐GCB type. In DLBCL, high co‐expression of MYC and BCL2 was an independent predictor of poor survival, and could be used to stratify patients for risk‐adapted therapies.     

A phase II trial of bendamustine in combination with rituximab in older patients with previously untreated diffuse large B‐cell lymphoma

Bendamustine in combination with rituximab (BR) has been associated with high response rates and acceptable toxicity in older patients with relapsed/refractory diffuse large B‐cell lymphoma (DLBCL). Evaluation of BR is warranted in the front‐line setting for DLBCL patients not eligible for anthracyclines or for the elderly. In this phase II study, we enrolled DLBCL patients aged ≥65 years who were poor candidates for R‐CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) to determine the efficacy and safety of BR in previously untreated stage II–IV DLBCL. Twenty‐three patients were enrolled with a median age of 80 years. 52% of patients presented with poor functional status (Eastern Cooperative Oncology Group performance score of ≥2). The overall response rate was 78% with 12 complete responses (52%). At a median follow up of 29 months, the median overall survival was 10·2 months and the median progression‐free survival was 5·4 months. The most common grade 3/4 adverse events were haematological. Combination therapy with BR demonstrates high response rates as front‐line therapy in frail older patients with DLBCL, but survival rates were low. BR should be used with caution in future clinical trials involving older DLBCL patients with poor functional status.     

CD30 expression in de novo diffuse large B‐cell lymphoma: a population‐based study from British Columbia

Diffuse large B‐cell lymphoma (DLBCL) is a heterogeneous disease with variable therapeutic responses and alternative therapies are needed for patients with unfavourable treatment outcomes after standard treatment with R‐CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone). One promising candidate is brentuximab vedotin, an antibody‐drug conjugate targeting CD30‐expressing cells. However, CD30 (TNFRSF8) expression patterns in DLBCL are not well described thus far. Here, we examined CD30 expression in a population‐based cohort of immunocompetent patients from British Columbia with de novo DLBCL using immunohistochemistry. 385 cases of formalin‐fixed paraffin‐embedded DLBCL in tissue microarrays were evaluated. 95 cases (25%) harboured CD30+ tumour cells. Using a > 0% cut‐off, CD30 expression was predictive of superior 5‐year progression‐free survival within R‐CHOP treated germinal centre B‐cell‐like (GCB) DLBCL (86% vs. 64%, P = 0·020), which was independent of the International Prognostic Index. Epstein‐Barr virus (EBV) was identified in 11 (3%) cases, all of which were non‐GCB (P = 0·001) and almost exclusively positive for CD30 expression (10/11) (P < 0·001). We conclude CD30 is expressed in a substantial proportion of DLBCL and CD30 immunohistochemistry may be a useful prognostic marker in R‐CHOP treated GCB‐DLBCL. The significant association of CD30 with EBV‐positive non‐GCB DLBCL suggests a distinct pathobiology for these cases.     

Outcomes of primary refractory diffuse large B‐cell lymphoma (DLBCL) treated with salvage chemotherapy and intention to transplant in the rituximab era

Rituximab‐containing salvage chemotherapy followed by high‐dose therapy and autologous stem cell transplant (ASCT ) in chemosensitive patients remains the standard of care for patients with relapsed and refractory diffuse large B‐cell lymphoma (DLBCL ). However, its role in those patients achieving less than a complete response to first‐line therapy (primary refractory disease) in the rituximab era is not well defined. We reviewed the outcomes of 82 transplant‐eligible patients with primary refractory DLBCL who underwent salvage therapy with the intent of administering high‐dose therapy and ASCT to patients achieving chemosensitive remission. The estimated 3‐year overall and progression‐free survival for all patients was 38% and 29%, respectively, and 65% and 60% respectively for patients proceeding to stem cell transplant. Long‐term remission was achieved in 45% of patients achieving a partial response (PR) to initial induction therapy and <20% of patients with stable or progression of disease following initial therapy. These results suggest that salvage chemotherapy with the intent of subsequent high‐dose therapy and ASCT remains a feasible strategy in certain patients with primary refractory DLBCL , particularly for those achieving a PR to frontline therapy. The primary barrier to curative therapy in patients with primary refractory disease is resistance to salvage therapy, and future studies should be aimed towards increasing the response rate in this population.     

Validation of the NCCN‐IPI for diffuse large B‐cell lymphoma (DLBCL): the addition of β2‐microglobulin yields a more accurate GELTAMO‐IPI

The study included 1848 diffuse large B‐cell lymphoma (DLBCL )patients treated with chemotherapy/rituximab. The aims were to validate the National Comprehensive Cancer Network International Prognostic Index (NCCN ‐IPI ) and explore the effect of adding high Beta‐2 microglobulin (β2M), primary extranodal presentation and intense treatment to the NCCN ‐IPI variables in order to develop an improved index. Comparing survival curves, NCCN ‐IPI discriminated better than IPI , separating four risk groups with 5‐year overall survival rates of 93%, 83%, 67% and 49%, but failing to identify a true high‐risk population. For the second aim the series was split into training and validation cohorts: in the former the multivariate model identified age, lactate dehydrogenase, Eastern Cooperative Oncology Group performance status, Stage III ‐IV , and β2M as independently significant, whereas the NCCN ‐IPI ‐selected extranodal sites, primary extranodal presentation and intense treatments were not. These results were confirmed in the validation cohort. The Grupo Español de Linfomas/Trasplante de Médula ósea (GELTAMO )‐IPI developed here, with 7 points, significantly separated four risk groups (0, 1–3, 4 or ≥5 points) with 11%, 58%, 17% and 14% of patients, and 5‐year overall survival rates of 93%, 79%, 66% and 39%, respectively. In the comparison GELTAMO IPI discriminated better than the NCCN ‐IPI . In conclusion, GELTAMO ‐IPI is more accurate than the NCCN ‐IPI and has statistical and practical advantages in that the better discrimination identifies an authentic high‐risk group and is not influenced by primary extranodal presentation or treatments of different intensity.     

Targeted resequencing for analysis of clonal composition of recurrent gene mutations in chronic lymphocytic leukaemia

Recurrent gene mutations contribute to the pathogenesis of chronic lymphocytic leukaemia (CLL). We developed a next‐generation sequencing (NGS) platform to determine the genetic profile, intratumoural heterogeneity, and clonal structure of two independent CLL cohorts. TP53, SF3B1, and NOTCH1 were most frequently mutated (16·3%, 16·9%, 10·7%). We found evidence for subclonal mutations in 67·5% of CLL cases with mutations of cancer consensus genes. We observed selection of subclones and found initial evidence for convergent mutations in CLL. Our data suggest that assessment of (sub)clonal structure may need to be integrated into analysis of the mutational profile in CLL.