Prognostic Significance of Diffuse Large B-Cell Lymphoma Cell of Origin Determined by Digital Gene Expression in Formalin-Fixed Paraffin-Embedded Tissue Biopsies

PURPOSE

To evaluate the prognostic impact of cell-of-origin (COO) subgroups, assigned using the recently described gene expression-based Lymph2Cx assay in comparison with International Prognostic Index (IPI) score and MYC/BCL2 coexpression status (dual expressers).

PATIENTS AND METHODS

Reproducibility of COO assignment using the Lymph2Cx assay was tested employing repeated sampling within tumor biopsies and changes in reagent lots. The assay was then applied to pretreatment formalin-fixed paraffin-embedded tissue (FFPET) biopsies from 344 patients with de novo diffuse large B-cell lymphoma (DLBCL) uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) at the British Columbia Cancer Agency. MYC and BCL2 protein expression was assessed using immunohistochemistry on tissue microarrays.

RESULTS

The Lymph2Cx assay provided concordant COO calls in 96% of 49 repeatedly sampled tumor biopsies and in 100% of 83 FFPET biopsies tested across reagent lots. Critically, no frank misclassification (activated B-cell-like DLBCL to germinal center B-cell-like DLBCL or vice versa) was observed. Patients with activated B-cell-like DLBCL had significantly inferior outcomes compared with patients with germinal center B-cell-like DLBCL (log-rank P < .001 for time to progression, progression-free survival, disease-specific survival, and overall survival). In pairwise multivariable analyses, COO was associated with outcomes independent of IPI score and MYC/BCL2 immunohistochemistry. The prognostic significance of COO was particularly evident in patients with intermediate IPI scores and the non-MYC-positive/BCL2-positive subgroup (log-rank P < .001 for time to progression).

CONCLUSION

Assignment of DLBCL COO by the Lymph2Cx assay using FFPET biopsies identifies patient groups with significantly different outcomes after R-CHOP, independent of IPI score and MYC/BCL2 dual expression.

The Prognostic Impact of CD163-Positive Macrophages in Follicular Lymphoma: A Study from the BC Cancer Agency and the Lymphoma Study Association

PURPOSE

We aimed to assess the prognostic significance of follicular lymphoma-associated macrophages in the era of rituximab treatment and maintenance.

EXPERIMENTAL DESIGN

We applied immunohistochemistry for CD68 and CD163 to two large tissue microarrays (TMA). The first TMA included samples from 186 patients from the BC Cancer Agency (BCCA) who had been treated with first-line systemic treatment including rituximab, cyclophosphamide, vincristine, and prednisone. The second contained 395 samples from PRIMA trial patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone, and randomized to rituximab maintenance or observation. Macrophage infiltration was assessed using Aperio image analysis. Each of the two cohorts was randomly split into training/validation sets.

RESULTS

An increased CD163-positive pixel count was predictive of adverse outcome in the BCCA dataset [5-year progression-free survival (PFS) 38% vs. 72%, respectively, P = 0.004 in the training cohort and 5-year PFS 29% vs. 61%, respectively, P = 0.004 in the validation cohort]. In the PRIMA trial, an increased CD163 pixel count was associated with favorable outcome (5-year PFS 60% vs. 44%, respectively, P = 0.011 in the training cohort and 5-year PFS 55% vs. 37%, respectively, P = 0.030 in the validation cohort).

CONCLUSIONS

CD163-positive macrophages predict outcome in follicular lymphoma, but their prognostic impact is highly dependent on treatment received.

Outcomes in splenic marginal zone lymphoma: analysis of 107 patients treated in British Columbia

Splenic marginal zone lymphoma (SMZL) accounts for less than 2% of all non-Hodgkin lymphomas. We identified 107 cases diagnosed with SMZL between 1985 and 2012 from the British Columbia Cancer Agency Centre for Lymphoid Cancer and Lymphoma Pathology Databases. Patient characteristics were: median age 67 years (range 30-88), male 40%, stage IV 98%, splenomegaly 93%, bone marrow involvement 96%, peripheral blood involvement 87%. As initial treatment, 52 underwent splenectomy (10 with chemotherapy), 38 chemotherapy alone (21 chemoimmunotherapy containing rituximab, 1 rituximab alone), two antivirals for hepatitis C, and 15 were only observed. The 10-year overall survival for first-line splenectomy versus chemotherapy was 61% and 42%, respectively [Hazard Ratio (HR) 0·48, 95% confidence interval (CI) 0·26-0·88, P = 0·017]. The 10-year failure-free survival (FFS) after first-line splenectomy vs chemotherapy was 39% and 14%, respectively (HR 0·48, 95% CI 0·28-0·80, P = 0·004). Among the 38 patients who received first-line chemotherapy, FFS was similar between those receiving rituximab (n = 22) and those who did not (n = 16) (HR 0·64, 95% CI 0·31-1·34, P = 0·238). Fifteen patients transformed to aggressive lymphoma with median time to transformation of 3·5 years (range 6 months to 12 years) and the 10-year transformation rate was 18%. In conclusion, splenectomy remains a reasonable treatment for patients with SMZL.

EBV may be expressed in the LP cells of nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) in both children and adults

Nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL) and classical Hodgkin lymphoma (CHL) are classified separately because of their distinct clinical and pathologic features. Whereas Epstein-Barr virus (EBV) is detected in the neoplastic cells of 25% to 70% of CHL, NLPHL is generally considered to be EBV(-). We assessed EBV status in 302 pediatric and adult cases of NLPHL. A total of 145 pediatric (age 18 y or younger) and 157 adult cases of NLPHL were retrieved from 3 North American centers and tested for EBV by in situ hybridization (EBV-encoded small RNA). Clinical and pathologic features were analyzed. Five (3.4%) pediatric and 7 (4.5%) adult NLPHL cases contained EBV(+) lymphocyte-predominant (LP) cells. Although all 12 cases met the criteria for diagnosis of NLPHL, atypical features were present, including capsular fibrosis, atrophic germinal centers, and pleomorphic or atypical LP cells. CD20 and OCT-2 were strongly and diffusely positive in all except 1 case. However, PAX5 and CD79a were weak and/or variable in 7/8 and 6/6 cases tested, respectively. EBV(+) cases were more likely to be CD30(+) (75%) compared with EBV(-) cases (25%) (P=0.0007); CD15 was negative in all cases. Our results show that EBV(+) LP cells may occur in NLPHL. Distinguishing EBV(+) NLPHL from CHL can be challenging, as EBV(+) NLPHL can have partial expression of CD30 and weak PAX5 staining as well as pleomorphic-appearing LP cells. However, the overall appearance and maintenance of B-cell phenotype, with strong and diffuse CD20 and OCT-2 expression, support the diagnosis of NLPHL in these cases.

International Prognostic Score in advanced-stage Hodgkin's lymphoma: altered utility in the modern era

PURPOSE

The International Prognostic Score (IPS) is the most widely used risk stratification index for Hodgkin's lymphoma (HL). It is based on patients treated before 1992 and predicts 5-year freedom from progression (FFP) and overall survival (OS) ranging from 42% to 84% and 56% to 89%, respectively. The IPS has not been validated in a recently treated population in which outcomes have improved compared with historic results.

PATIENTS AND METHODS

By using the British Columbia Cancer Agency Lymphoid Cancer Database, we identified all patients age ≥ 16 years newly diagnosed with advanced-stage HL (stage III to IV, or stage I to II with "B" symptoms or bulky disease ≥ 10 cm) from 1980 to 2010, treated with curative intent with doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) or an ABVD-equivalent regimen with complete clinical information.

RESULTS

In all, 740 patients were identified. Five-year FFP and OS were 78% and 90%, respectively. The IPS was prognostic for both FFP (P < .001) and OS (P < .001), with 5-year FFP ranging from 62% to 88% and 5-year OS ranging from 67% to 98%. Analysis limited to patients age 16 to 65 years (n = 686) demonstrated a narrower range of outcomes, with 5-year FFP ranging from 70% to 88% and 5-year OS ranging from 73% to 98%.

CONCLUSION

The IPS remains prognostic for advanced-stage HL, but the range of outcomes has narrowed considerably. This improvement in outcome with ABVD should be acknowledged before consideration of alternate initial therapies and when comparing results from current trials with those of historic controls.

Concurrent expression of MYC and BCL2 in diffuse large B-cell lymphoma treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) is curable in 60% of patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). MYC translocations, with or without BCL2 translocations, have been associated with inferior survival in DLBCL. We investigated whether expression of MYC protein, with or without BCL2 protein expression, could risk-stratify patients at diagnosis.

PATIENTS AND METHODS

We determined the correlation between presence of MYC and BCL2 proteins by immunohistochemistry (IHC) with survival in two independent cohorts of patients with DLBCL treated with R-CHOP. We further determined if MYC protein expression correlated with high MYC mRNA and/or presence of MYC translocation.

RESULTS

In the training cohort (n = 167), MYC and BCL2 proteins were detected in 29% and 44% of patients, respectively. Concurrent expression (MYC positive/BCL2 positive) was present in 21% of patients. MYC protein correlated with presence of high MYC mRNA and MYC translocation (both P < .001), but the latter was less frequent (both 11%). MYC protein expression was only associated with inferior overall and progression-free survival when BCL2 protein was coexpressed (P < .001). Importantly, the poor prognostic effect of MYC positive/BCL2 positive was validated in an independent cohort of 140 patients with DLBCL and remained significant (P < .05) after adjusting for presence of high-risk features in a multivariable model that included elevated international prognostic index score, activated B-cell molecular subtype, and presence of concurrent MYC and BCL2 translocations.

CONCLUSION

Assessment of MYC and BCL2 expression by IHC represents a robust, rapid, and inexpensive approach to risk-stratify patients with DLBCL at diagnosis.

TBL1XR1/TP63: a novel recurrent gene fusion in B-cell non-Hodgkin lymphoma

Recently, the landscape of single base mutations in diffuse large B-cell lymphoma (DLBCL) was described. Here we report the discovery of a gene fusion between TBL1XR1 and TP63, the only recurrent somatic novel gene fusion identified in our analysis of transcriptome data from 96 DLBCL cases. Based on this cohort and a further 157 DLBCL cases analyzed by FISH, the incidence in de novo germinal center B cell-like (GCB) DLBCL is 5% (6 of 115). The fusion appears exclusive to GCB and was not seen in 138 non-GCB cases examined (P = .008, Fisher exact test) but was present at low incidence in follicular lymphoma (1 of 81). In all 7 cases identified, the 3' end of the fusion consists of exons 4 and onwards of TP63. The recurrence, subtype enrichment, and the remarkably conserved nature of the TP63 portion of the fusion suggest an important functional role in the lymphomas that harbor this event.

B cells with high side scatter parameter by flow cytometry correlate with inferior survival in diffuse large B-cell lymphoma

Despite advances in the understanding of diffuse large B-cell lymphoma (DLBCL) biology, only the clinically based International Prognostic Index (IPI) is used routinely for risk stratification at diagnosis. To find novel prognostic markers, we analyzed flow cytometric data from 229 diagnostic DLBCL samples using an automated multiparameter data analysis approach developed in our laboratory. By using the developed automated data analysis pipeline, we identified 71 of 229 cases as having more than 35% B cells with a high side scatter (SSC) profile, a parameter reflecting internal cellular complexity. This high SSC B-cell feature was associated with inferior overall and progression-free survival (P = .001 and P = .01, respectively) and remained a significant predictor of overall survival in multivariate Cox regression analysis (IPI, P = .001; high SSC, P = .004; rituximab, P = .53). This study suggests that high SSC among B cells may serve as a useful biomarker to identify patients with DLBCL at high risk for relapse. This is of particular interest because this biomarker is readily available in most clinical laboratories without significant alteration to existing routine diagnostic strategies or incurring additional costs.

BCL2 mutations in diffuse large B-cell lymphoma

BCL2 is deregulated in diffuse large B-cell lymphoma (DLBCL) by the t(14;18) translocation, gene amplification and/or nuclear factor-κB signaling. RNA-seq data have recently shown that BCL2 is the most highly mutated gene in germinal center B-cell (GCB) DLBCL. We have sequenced BCL2 in 298 primary DLBCL biopsies, 131 additional non-Hodgkin lymphoma biopsies, 24 DLBCL cell lines and 51 germline DNAs. We found frequent BCL2 mutations in follicular lymphoma (FL) and GCB DLBCL, but low levels of BCL2 mutations in activated B-cell DLBCL, mantle cell lymphoma, small lymphocytic leukemia and peripheral T-cell lymphoma. We found no BCL2 mutations in GC centroblasts. Many mutations were non-synonymous; they were preferentially located in the flexible loop domain, with few in BCL2-homology domains. An elevated transition/transversions ratio supports that the mutations result from somatic hypermutation. BCL2 translocations correlate with, and are likely important in acquisition of, additional BCL2 mutations in GCB DLBCL and FL. DLBCL mutations were not independently associated with survival. Although previous studies of BCL2 mutations in FL have reported mutations to result in pseudo-negative BCL2 protein expression, we find this rare in de-novo DLBCL.

Flow cytometric detection of ZAP-70 in chronic lymphocytic leukemia: correlation with immunocytochemistry and Western blot analysis

CONTEXT

Expression of ZAP-70 in chronic lymphocytic leukemia (CLL) predicts worse clinical outcome in patients with early-stage disease. It has become important to include ZAP-70 in the immunophenotyping panel used to diagnose CLL, commonly performed by flow cytometry (FC). Nevertheless, the methodology used to detect ZAP-70 by FC has not been extensively evaluated.

OBJECTIVE

To describe our FC method for detecting ZAP-70 in CLL and assess whether this assay is useful in estimating the ZAP-70 protein level in CLL cells.

DESIGN

ZAP-70 expression was assessed by FC in 45 consecutive newly diagnosed CLL patients, and the results were correlated with those of immunocytochemistry and Western blot analysis.

RESULTS

With >25% ZAP-70-positive B cells as the cutoff, the FC results had a perfect concordance with those of immunocytochemistry (39/39, 100%) and Western blot analysis (7/7, 100%). The use of autofluorescence controls was found to be superior to other alternatives. Overall, 19 (42%) of 45 cases were ZAP-70 positive in our series. Since only 7 cases (16%) had >20% to 30% ZAP-70-positive B cells, the cutoff of >25% readily separated CLL into positive and negative groups in most cases. ZAP-70 positivity was significantly associated with atypical morphology but not other laboratory parameters evaluated.

CONCLUSIONS

With proper specimen processing and the use of directly fluorescence-conjugated anti-ZAP-70 antibody, one can readily incorporate ZAP-70 into the routine FC study panel for CLL. Our data suggest that FC is a rapid and useful method to estimate the ZAP-70 protein expression level in CLL.