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Abstract Polatuzumab vedotin is a CD79b‐directed antibody–drug conjugate that targets B cells and delivers the cytotoxic payload monomethyl auristatin E (MMAE). The phase III POLARIX study (NCT03274492) evaluated polatuzumab vedotin in combination with rituximab, cyclophosphamide, doxorubicin, and prednisone (R‐CHP) as first‐line treatment of diffuse large B‐cell lymphoma (DLBCL). To examine dosing decisions for this regimen, population pharmacokinetic (popPK) analysis, using a previously developed popPK model, and exposure–response (ER) analysis, were performed. The popPK analysis showed no clinically meaningful relationship between cycle 6 (C6) antibody‐conjugated (acMMAE)/unconjugated MMAE area under the concentration–time curve (AUC) or maximum concentration, and weight, sex, ethnicity, region, mild or moderate renal impairment, mild hepatic impairment, or other patient and disease characteristics. In the ER analysis, C6 acMMAE AUC was significantly associated with longer progression‐free and event‐free survival (both p = 0.01). An increase of

Purpose: The optimal management of stage II follicular lymphoma (FL) is unclear. Radiation therapy (RT) alone has been the gold standard treatment, but a proportion of patients relapse. We sought to characterize outcomes and prognostic factors for stage II FL treated with RT alone to identify a high-risk subgroup of patients who may benefit from treatment intensification. Methods: This was a population-based, province-wide, retrospective study. Included patients had grade 1–3A, non-mesenteric, stage IIA or IIAE FL diagnosed between 1986 and 2016 and treated with curative-intent (≥20 Gy) RT alone. Results: 102 patients were included. Median follow-up was 10.4 years (range, 0.3–22.3). Median age was 59 years (range, 33–86). Median greatest disease diameter was 3.6 cm (range, 1.5–11.5). Freedom from progression (FFP) was 60.3% at 5 years and 40.7% at 10 years. Overall survival (OS) was 89.2% at 5 years and 81.8% at 10 years. Greatest disease diameter of >3.6 cm was associated with inferior FFP (10-year FFP 34% vs. 47%, p = 0.013) on univariable analysis and inferior FFP (hazard ratio [HR] 1.87, p = 0.019) and inferior OS (HR 2.12, p = 0.027) on multivariable analysis (MVA). Older age was associated with inferior OS (HR 1.08, unit = 1 year, p 3.6 cm was associated with inferior FFP and OS, representing a novel prognostic indicator in this population that may help in the decision-making process on whether to complement RT with systemic therapy.

Abstract The Lugano 2014 criteria are the standard for response assessment in lymphoma. We compared the prognostic performance of Lugano 2014 and the more recently developed response evaluation criteria in lymphoma (RECIL 2017), which relies primarily on computed tomography and uses unidimensional measurements, in patients with previously untreated diffuse large B‐cell lymphoma (DLBCL) and follicular lymphoma (FL) from the phase III GOYA and GALLIUM trials, respectively. Concordance between responses according to the Lugano 2014 and RECIL 2017 criteria was analyzed. Landmark analyses of progression‐free survival (PFS) and overall survival (OS) by end of treatment (EOT) and end of induction (EOI) response status according to RECIL 2017 and Lugano 2014 criteria, and prognostic value of response at EOT/EOI were also compared. Overall, 1333 patients were included from GOYA and 502 from GALLIUM. Complete response (CR) status according to RECIL 2017 criteria showed high concordance with complete metabolic response (CMR) status by Lugano 2014 criteria in both GOYA (92.5%) and GALLIUM (92.4%). EOT and EOI CR/CMR status by both criteria was highly prognostic for PFS in GOYA (RECIL 2017 [CR]: hazard ratio [HR], 0.35 [95% confidence interval [CI] 0.26–0.46]; Lugano 2014 [CMR]: HR, 0.35 [95% CI 0.26–0.48]; both p

Follicular lymphoma (FL) is the most common type of indolent non-Hodgkin lymphoma. Despite treatment advances that have improved outcomes for patients with relapsed or refractory (R/R) FL, many patients still die from progressive disease or treatment-related toxicities. In the phase Ib/II GO29365 study (clinicaltrials.gov 02257567), the safety and efficacy of polatuzumab vedotin plus bendamustine and rituximab (Pola-BR) versus bendamustine and rituximab (BR) alone, and polatuzumab vedotin plus bendamustine and obinutuzumab (Pola-BG) as a single-arm cohort were evaluated in patients with R/R FL. Following the phase Ib safety run-in, patients were randomized 1:1 to receive Pola-BR or BR alone in the phase II stage; a separate non-randomized Pola-BG cohort was examined in the phase Ib/II expansion stage. Primary endpoints included safety and tolerability (phase Ib) and positron emission tomography complete response (PET-CR) rate by independent review committee (phase II). Overall, 112 patients were enrolled (phase Ib safety run-in: Pola-BR, N=6; phase II randomized cohort: Pola-BR, N=39; BR, N=41; phase Ib/II expansion cohort: Pola-BG, N=26). PET-CR rates were 66.7% (phase Ib safety run-in, Pola-BR); 69.2% (phase II randomized, Pola-BR); 63.4% (phase II randomized, BR); and 65.4% (phase Ib/II expansion Pola-BG). There was a higher occurrence of cytopenias with Pola-BR and Pola-BG than with BR; serious adverse events were more frequent with Pola-BR (61.4%) and Pola-BG (46.2%) than with BR (29.3%). Overall, this analysis does not demonstrate a benefit of adding Pola to BR or BG regimens for patients with R/R FL.

Follicular lymphoma can transform to a more aggressive histology. Here, the authors use bulk and single cell analysis to create a 26 marker panel which could be used to profile FL samples and predict the risk of transformation using flow cytometry.

Waldenström macroglobulinemia (WM) is a slowly progressing B-cell non-Hodgkin lymphoma characterized by monoclonal IgM gammopathy in the blood and infiltration of the bone marrow by clonal lymphoplasmacytic cells. As an incurable disease, the goals for therapy for WM are to relieve symptoms, slow disease progression, prevent organ damage, and maintain quality of life. However, given the rarity of WM, clinical trials comparing treatments for WM are limited and there is no definitive standard of care. The selection of first-line WM therapy is thus based on patient factors, disease characteristics, and drug access, with bendamustine-rituximab and Bruton’s tyrosine kinase (BTK) inhibitor therapy considered preferred treatments. Other treatments such as proteasome inhibitor- or purine analogue-based therapy, alternative chemoimmunotherapy, and autologous stem cell transplantation are generally reserved for the relapsed setting but may be used in rare circumstances in earlier lines of therapy. This paper summarizes the efficacy and safety of these WM therapies and discusses considerations for treatment from a Canadian perspective.

Abstract Image texture analysis (radiomics) uses radiographic images to quantify characteristics that may identify tumour heterogeneity and associated patient outcomes. Using fluoro‐deoxy‐glucose positron emission tomography/computed tomography (FDG‐PET/CT)‐derived data, including quantitative metrics, image texture analysis and other clinical risk factors, we aimed to develop a prognostic model that predicts survival in patients with previously untreated diffuse large B‐cell lymphoma (DLBCL) from GOYA (NCT01287741). Image texture features and clinical risk factors were combined into a random forest model and compared with the international prognostic index (IPI) for DLBCL based on progression‐free survival (PFS) and overall survival (OS) predictions. Baseline FDG‐PET scans were available for 1263 patients, 832 patients of these were cell‐of‐origin (COO)‐evaluable. Patients were stratified by IPI or radiomics features plus clinical risk factors into low‐, intermediate‐ and high‐risk groups. The random forest model with COO subgroups identified a clearer high‐risk population (45% 2‐year PFS [95% confidence interval (CI) 40%–52%]; 65% 2‐year OS [95% CI 59%–71%]) than the IPI (58% 2‐year PFS [95% CI 50%–67%]; 69% 2‐year OS [95% CI 62%–77%]). This study confirms that standard clinical risk factors can be combined with PET‐derived image texture features to provide an improved prognostic model predicting survival in untreated DLBCL.

Patients with hematological malignancies have an increased risk of serious outcomes following COVID-19 infection, suggesting broader protection is needed beyond vaccination. Monoclonal antibodies such as sotrovimab, casirivimab–imdevimab, and bamlanivimab have provided valuable options for the treatment of COVID-19 disease. More recently, monoclonal antibodies have been examined for the prevention of COVID-19 infection. The monoclonal antibody combination, tixagevimab–cilgavimab, was recently approved by Health Canada as pre-exposure prophylaxis against COVID-19 in individuals who are immunocompromised or where vaccination is not recommended. Prophylactic approaches such as the use of tixagevimab–cilgavimab, in addition to COVID-19 vaccination, may provide additional protection for patients with hematological malignancies who are at greater risk of serious outcomes from COVID-19 infection.

Abstract Background Rituximab (R) plus cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) is the current standard therapy for diffuse large B cell lymphoma (DLBCL). Obinutuzumab (G), a glycoengineered, type II anti-CD20 monoclonal antibody, has shown activity and an acceptable safety profile when combined with CHOP (G-CHOP) in patients with advanced DLBCL. We present the final analysis results of the Phase III GOYA study (NCT01287741), which compared the efficacy and safety of G-CHOP versus R-CHOP in patients with previously untreated DLBCL. Methods Patients aged ≥ 18 years with previously untreated advanced DLBCL were randomly assigned to receive eight 21-day cycles of R or G, plus six or eight cycles of CHOP. The primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints included overall survival, other time-to-event endpoints, and safety; investigator-assessed PFS by cell of origin subgroup was an exploratory endpoint. Results A total of 1418 patients were randomized, with 1414 included in this final analysis (G-CHOP, N = 704; R-CHOP, N = 710). Five-year PFS rates were 63.8% and 62.6% for G-CHOP and R-CHOP, respectively (stratified hazard ratio 0.94, 95% CI 0.78–1.12; p = 0.48). The results of the secondary efficacy endpoints did not show a benefit of G-CHOP over R-CHOP. In the exploratory analysis, a trend towards benefit with G-CHOP over R-CHOP was apparent in the patients with germinal center B cell DLBCL. The safety profile of G-CHOP was as expected, and no new safety signals were observed. More grade 3–5 (75.1% vs 65.8%), serious (44.4% vs 38.4%), and fatal (6.1% vs 4.4%) adverse events (AEs) were observed in the G-CHOP arm compared with the R-CHOP arm, respectively, with the most common fatal AEs being infections. A higher incidence of late-onset neutropenia occurred in the G-CHOP arm (8.7%) versus the R-CHOP arm (4.9%). Conclusions The final analysis, similar to the primary analysis, did not show a PFS benefit of G-CHOP over R-CHOP in previously untreated patients with DLBCL. The results of the secondary endpoints were consistent with the primary endpoint. Further exploratory analyses and investigation of biomarkers are ongoing.

Abstract: The objective of this study was to evaluate the distribution and prognostic impact of a broad range of molecular attributes in a large cohort of immunocompetent patients with primary central nervous system lymphoma (PCNSL) by using tissue microarray. Patients diagnosed with PCNSL were initially identified in the BC Cancer Lymphoid Cancer clinical and pathology databases. Tissue microarrays were constructed by using archival formalin-fixed paraffin-embedded diagnostic biopsy tissue. Immunohistochemistry and fluorescent in situ hybridization studies were performed. A total of 115 patients with PCNSL with diffuse large B-cell lymphoma (DLBCL) histology were identified. The majority of cases (≥75%) had a non–germinal center B-cell phenotype according to immunohistochemistry algorithms, but cell of origin did not affect progression-free or overall survival. MYC (40%), BCL2 (75%), and programmed death-ligand 1 (29%) protein expression were common, but their corresponding gene rearrangements were rare (≤1% each), suggesting that alternate mechanisms were driving expression. There were no dual rearrangements involving MYC and BCL2. Only 22% of cases had membranous expression of major histocompatibility complex class II, suggesting a mechanism for escape from immune surveillance. Epstein-Barr virus–encoded RNA was positive in 1 immunocompetent patient. BCL6 protein expression (77%) and BCL6 rearrangements (31%) were frequent; the latter was the only factor associated with a poor prognosis in the overall cohort and in the subgroup of 52 patients treated with high-dose methotrexate–based regimens. This large population-based study shows that prominent molecular features of PCNSL are unique and different from those of systemic DLBCL. These results may better inform drug development in PCNSL.

Abstract: In advanced-stage diffuse large B-cell lymphoma (DLBCL), the presence of an activated B-cell phenotype or a non–germinal center (GCB) phenotype, coexpression of MYC and BCL2 by immunohistochemistry, and the cooccurrence of MYC and BCL2 or BCL6 rearrangements are associated with inferior outcomes. It is unclear whether these variables remain prognostic in stage I/II patients. In this retrospective study, we evaluated the prognostic impact of cell of origin (COO), as well as dual-expressor (DE) status and molecular double-hit (DH) status, in stage I/II DLBCL by positron emission tomography with computed tomography (PET-CT). A total of 211 patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone)–like regimens, with or without radiotherapy, was included. The median follow-up in the entire cohort was 4 years (range, 0.4-9.4), with estimated 4-year progression-free survival (PFS) and overall survival (OS) rates of 85% (95% confidence interval [CI], 79-89) and 88% (95% CI, 83-92), respectively. By univariable analysis, DE (PFS: hazard ratio [HR], 1.27; 95% CI, 0.58-2.81, P = .55 and OS: HR, 1.40; 95% CI, 0.60-3.30; P = .44), DH (PFS: HR, 1.21; 95% CI, 0.27-5.31; P = .80 and OS: HR, 0.61; 95% CI, 0.08-4.73; P = .64), and non-GCB status (PFS: HR, 1.59; 95% CI, 0.83-3.03; P = .16 and OS: HR, 1.80; 95% CI, 0.89-3.67; P = .10) were associated with poorer outcomes. In patients with PET-CT–defined stage I/II DLBCL treated with R-CHOP–like therapy, with or without radiation, COO and DE and DH status were not significantly associated with inferior PFS or OS.

This retrospective analysis of the phase III GOYA study investigated the prognostic value of baseline metabolic tumor volume parameters and maximum standardized uptake values for overall and progression-free survival (PFS) in treatment-naïve diffuse large B-cell lymphoma. Baseline total metabolic tumor volume (determined for tumors >1 mL using a threshold of 1.5 times the mean liver standardized uptake value +2 standard deviations), total lesion glycolysis, and maximum standardized uptake value positron emission tomography data were dichotomized based on receiver operating characteristic analysis and divided into quartiles by baseline population distribution. Of 1,418 enrolled patients, 1,305 had a baseline positron emission tomography scan with detectable lesions. Optimal cut-offs were 366 cm3 for total metabolic tumor volume and 3,004 g for total lesion glycolysis. High total metabolic tumor volume and total lesion glycolysis predicted poorer PFS, with associations retained after adjustment for baseline and disease characteristics (high total metabolic tumor volume hazard ratio: 1.71, 95% confidence interval [CI]: 1.35– 2.18; total lesion glycolysis hazard ratio: 1.46; 95% CI: 1.15–1.86). Total metabolic tumor volume was prognostic for PFS in subgroups with International Prognostic Index scores 0–2 and 3–5, and those with different cell-of-origin subtypes. Maximum standardized uptake value had no prognostic value in this setting. High total metabolic tumor volume associated with high International Prognostic Index or non-germinal center B-cell classification identified the highest-risk cohort for unfavorable prognosis. In conclusion, baseline total metabolic tumor volume and total lesion glycolysis are independent predictors of PFS in patients with diffuse large B-cell lymphoma after first-line immunochemotherapy.

Abstract: Gray zone lymphoma (GZL) is described as sharing features with classical Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL). However, there remains complexity in establishing diagnosis, delineating prognosis, and determining optimum therapy. Sixty-eight cases diagnosed as GZL across 15 North American academic centers were evaluated by central pathology review to achieve consensus. Of these, only 26 (38%) were confirmed as GZL. Morphology was critical to GZL consensus diagnosis (eg, tumor cell richness); immunohistochemistry showed universal B-cell derivation, frequent CD30 expression, and rare Epstein-Barr virus (EBV) positivity (CD20+, 83%; PAX5+, 100%; BCL6+, 20%; MUM1+, 100%; CD30+, 92%; EBV+, 4%). Forty-two cases were reclassified: nodular sclerosis (NS) cHL, n = 27 (including n = 10 NS grade 2); lymphocyte predominant HL, n = 4; DLBCL, n = 4; EBV+ DLBCL, n = 3; primary mediastinal large BCL n = 2; lymphocyte-rich cHL and BCL–not otherwise specified, n = 1 each. GZL consensus-confirmed vs reclassified cases, respectively, more often had mediastinal disease (69% vs 41%; P = .038) and less likely more than 1 extranodal site (0% vs 25%; P = .019). With a 44-month median follow-up, 3-year progression-free survival (PFS) and overall survival for patients with confirmed GZL were 39% and 95%, respectively, vs 58% and 85%, respectively, for reclassified cases (P = .19 and P = .15, respectively). Interestingly, NS grade 2 reclassified patients had similar PFS as GZL consensus-confirmed cases. For prognostication of GZL cases, hypoalbuminemia was a negative factor (3-year PFS, 12% vs 64%; P = .01), whereas frontline cyclophosphamide, doxorubicin, vincristine, and prednisone ± rituximab (CHOP±R) was associated with improved 3-year PFS (70% vs 20%; P = .03); both factors remained significant on multivariate analysis. Altogether, accurate diagnosis of GZL remains challenging, and improved therapeutic strategies are needed.

Diffuse large B-cell lymphoma represents a biologically and clinically heterogeneous diagnostic category with well-defined cell-of-origin subtypes. Using data from the GOYA study (NCT01287741), we characterized the mutational profile of diffuse large B-cell lymphoma and evaluated the prognostic impact of somatic mutations in relation to cell-of-origin. Targeted DNA next-generation sequencing was performed in 499 formalin-fixed paraffin-embedded tissue biopsies from previously untreated patients. Prevalence of genetic alterations/mutations was examined. Multivariate Cox regression was used to evaluate the prognostic effect of individual genomic alterations. Of 465 genes analyzed, 59 were identified with mutations occurring in at least 10 of 499 patients (≥2% prevalence); 334 additional genes had mutations occurring in ≥1 patient. Single nucleotide variants were the most common mutation type. On multivariate analysis, BCL2 alterations were most strongly associated with shorter progression-free survival (multivariate hazard ratio: 2.6; 95% confidence interval: 1.6 to 4.2). BCL2 alterations were detected in 102 of 499 patients; 92 had BCL2 translocations, 90% of whom had germinal center B-cell-like diffuse large B-cell lymphoma. BCL2 alterations were also significantly correlated with BCL2 gene and protein expression levels. Validation of published mutational subsets revealed consistent patterns of co-occurrence, but no consistent prognostic differences between subsets. Our data confirm the molecular heterogeneity of diffuse large B-cell lymphoma, with potential treatment targets occurring in distinct cell-of-origin subtypes. clinicaltrials.gov identifier: NCT01287741.

In follicular lymphoma, studies addressing the prognostic value of microenvironment-related immunohistochemical markers and tumor cell-related genetic markers have yielded conflicting results, precluding implementation in practice. Therefore, the Lunenburg Lymphoma Biomarker Consortium performed a validation study evaluating published markers. To maximize sensitivity, an end of spectrum design was applied for 122 uniformly immunochemotherapy-treated follicular lymphoma patients retrieved from international trials and registries. The criteria were: early failure, progression or lymphoma-related death 5 years. Immunohistochemical staining for T cells and macrophages was performed on tissue microarrays from initial biopsies and scored with a validated computer-assisted protocol. Shallow whole-genome and deep targeted sequencing was performed on the same samples. The 96/122 cases with complete molecular and immunohistochemical data were included in the analysis. EZH2 wild-type (P=0.006), gain of chromosome 18 (P=0.002), low percentages of CD8+ cells (P=0.011) and CD163+ areas (P=0.038) were associated with early failure. No significant differences in other markers were observed, thereby refuting previous claims of their prognostic significance. Using an optimized study design, this Lunenburg Lymphoma Biomarker Consortium study substantiates wild-type EZH2 status, gain of chromosome 18, low percentages of CD8+ cells and CD163+ area as predictors of early failure to immunochemotherapy in follicular lymphoma treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP [-like]), while refuting the prognostic impact of various other markers.

Vascular endothelial growth factor is involved in lymphoma growth, suggesting a potential role for anti-vascular endothelial growth factor therapies in hematologic malignancies. In this phase III study, patients with CD20-positive diffuse large B-cell lymphoma were randomized to rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone plus either placebo (R-CHOP) or bevacizumab (RA-CHOP). Treatment was administered every 21 (8 cycles) or 14 days (6 cycles plus 2 rituximab cycles) as per institutional practice. An early analysis of risk/benefit by the Data and Safety Monitoring Board showed that RA-CHOP increased cardiotoxicity without prolonging progression-free survival compared with R-CHOP, and the trial was stopped early. The study protocol was amended to allow for 12 additional months of follow up to evaluate safety. With 787 patients enrolled, median follow up was 23.7 and 23.6 months for R-CHOP and RA-CHOP, respectively. Median progression-free survival for R-CHOP and RA CHOP was 42.9 and 40.2 months, respectively (hazard ratio=1.09; P=0.49). The proportion of deaths was identical for R-CHOP (83 of 387, 21%) and RA-CHOP (82 of 390, 21%). Relative to R-CHOP, RA-CHOP had a higher rate of left ventricular ejection fraction perturbation (18% vs. 8%; odds ratio=2.51; 95% confidence interval (CI): 1.60–3.93) and congestive heart failure (16% vs. 7%; odds ratio=2.79; 95%CI: 1.72–4.54). Bevacizumab added to R-CHOP increased cardiac events, without increasing efficacy, arguing against further evaluation of RA-CHOP in patients with diffuse large B-cell lymphoma. The MAIN study is registered at clinicaltrials.gov identifier:00486759.

Background Renal involvement is uncommon in diffuse large B-cell lymphoma. Recent data suggest that it is an independent risk factor for central nervous system relapse. We reviewed the clinical features, risk of central nervous system involvement, and survival of patients with diffuse large B-cell lymphoma with involvement of the kidney at diagnosis.Design and Methods All patients with diffuse large B-cell lymphoma and renal involvement diagnosed from January 1, 1982 to December 31, 2008 at the British Columbia Cancer Agency were retrospectively identified in the Lymphoid Cancer Database. Patients were included if they were 16 years old or over, had advanced stage disease [stage III/IV, or stage I/II with B symptoms or bulky mass (>10 cm)] and were treated with curative intent. Central nervous system involvement was diagnosed by cerebrospinal fluid cytology, radiology or clinically.Results We identified 55/2656 (2%) patients with diffuse large B-cell lymphoma and renal involvement at diagnosis. The male to female ratio was 2:1. The patients’ median age was 58 years. Bilateral renal involvement was present in 24 (44%) and stage IV disease in 50 (91%). The International Prognostic Index score was 3, 4 or 5 in 52 (95%), the glomerular filtration rate was less than 30 mL/min/m2 in 9 (16%) and elevated lactate dehydrogenase was recorded in 46 (84%). Twenty-five (46%) patients received CHOP plus rituximab and 30 (54%) received CHOP-like regimens without rituximab. In total, 20 (36%) patients had central nervous system involvement: four at the time of diagnosis and 16 at relapse. The median time to central nervous system relapse was 5.6 months (range, 1.2 months–4.6 years), and was not affected by the addition of rituximab (P=0.547). The 5-year overall and progression-free survival rates for the whole cohort were 29% and 25%, respectively. In patients who received rituximab, there were trends towards improved 5-year overall survival (43% versus 18%, P=0.071) and progression-free survival (40% versus 13%, P=0.057).Conclusions There is an exceptionally high incidence of central nervous system relapse in patients with diffuse large B-cell lymphoma and kidney involvement at diagnosis. The addition of rituximab may improve overall survival in this poor-risk population, likely through improved control of systemic disease.

Background BCL6 gene rearrangement is the most frequent chromosomal abnormality in diffuse large B-cell lymphoma, a malignancy characterized by genetic heterogeneity and wide variability in clinical outcome. The prognostic significance of BCL6 rearrangement has not been evaluated in the context of rituximab therapy for diffuse large B-cell lymphoma. We analyzed the effect of the BCL6 rearrangement on survival in patients with diffuse large B-cell lymphoma treated with CHOP and CHOP plus rituximab (R-CHOP).Design and Methods BCL6 rearrangement status was analyzed by fluorescence in situ hybridization with break-apart probes in 164 patients with diffuse large B-cell lymphoma treated with CHOP (n=65) or R-CHOP (n=99). Cell-of-origin immunophenotype including BCL6 protein expression were determined by immunohistochemistry on a tissue microarray.Results BCL6 rearrangement was detected in 19.5% of cases. The presence of the gene rearrangement was associated with a non-germinal center B-cell immunophenotype (P=0.006), and showed no correlation with BCL6 protein expression. A trend toward inferior overall survival was observed in association with the BCL6 rearrangement among patients treated with R-CHOP (P=0.08), but not among patients treated with CHOP (P=0.64). However, BCL6 rearrangement also correlated with a high International Prognostic Index score (P=0.02), and did not demonstrate independent prognostic value by multivariate analysis.Conclusions The introduction of rituximab may have altered the prognostic impact of BCL6 gene rearrangement in patients with diffuse large B-cell lymphoma. However, prospective analysis within large randomized clinical trials will be needed to clarify the prognostic significance of this biomarker in the rituximab era.

Rituximab binds an epitope on the CD20 antigen, encompassed in exon 5 of the MS4A1 gene. We sequenced this region and correlated the presence of mutations with CD20 protein expression and response to R-CHOP in patients with diffuse large B-cell lymphoma: 264 diagnostic biopsies and 15 biopsies taken at the time of relapse were successfully sequenced. CD20 mutations involving the rituximab epitope were detected in only 1/264 (0.4%) and 1/15 (6%) of the biopsies taken at diagnosis and relapse, respectively. No polymorphic sequence variants were detected in this region. Three patients had malignant cells that were CD20 protein-positive at diagnosis but CD20-negative at relapse. Thus, CD20 mutations involving the rituximab epitope are rare in both de novo and relapsed diffuse large B-cell lymphoma, and do not represent a significant cause of R-CHOP resistance. CD20 protein-negative relapses occur after R-CHOP therapy but their clinical relevance is unknown.