Motive and Opportunity: MYC rearrangements in high-grade B-cell lymphoma with MYC and BCL2 rearrangements-an LLMPP study

Rearrangements that place the oncogenes MYC, BCL2, or BCL6 adjacent to superenhancers are common in mature B-cell lymphomas. Lymphomas with diffuse large B-cell lymphoma (DLBCL) or high-grade morphology with both MYC and BCL2 rearrangements are classified as high-grade B-cell lymphoma with MYC and BCL2 rearrangements ("double hit": HGBCL-DH-BCL2) and are associated with aggressive disease and poor outcomes. Although it is established that MYC rearrangements involving immunoglobulin (IG) loci are associated with inferior outcomes relative to those involving other non-IG superenhancers, the frequency of, and mechanisms driving, IG vs non-IG MYC rearrangements have not been elucidated. Here we used custom targeted capture and/or whole genome sequencing to characterize oncogene rearrangements across 883 mature B-cell lymphomas including Burkitt lymphoma, follicular lymphoma, DLBCL, and HGBCL-DH-BCL2 tumors. We demonstrate that, while BCL2 rearrangement topology is consistent across entities, HGBCL-DH-BCL2 have distinct MYC rearrangement architecture relative to tumors with single MYC rearrangements or with both MYC and BCL6 rearrangements (HGBCL-DH-BCL6), including both a higher frequency of non-IG rearrangements and different architecture of MYC::IGH rearrangements. The distinct MYC rearrangement patterns in HGBCL-DH-BCL2 occur on the background of high levels of somatic hypermutation across MYC partner loci in HGBCL-DH-BCL2, creating more opportunity to form these rearrangements. Furthermore, because one IGH allele is already disrupted by the existing BCL2 rearrangement, the MYC rearrangement architecture in HGBCL-DH-BCL2 likely reflects selective pressure to preserve both BCL2 and B cell receptor expression. These data provide new mechanistic explanations for the distinct patterns of MYC rearrangements observed across different lymphoma entities.

TRAF3 loss-of-function reveals the noncanonical NF-κB pathway as a therapeutic target in diffuse large B cell lymphoma

Here, we report recurrent focal deletions of the chr14q32.31-32 locus, including TRAF3, a negative regulator of NF-κB signaling, in de novo diffuse large B cell lymphoma (DLBCL) (24/324 cases). Integrative analysis revealed an association between TRAF3 copy number loss with accumulation of NIK, the central noncanonical (NC) NF-κB kinase, and increased NC NF-κB pathway activity. Accordingly, TRAF3 genetic ablation in isogenic DLBCL model systems caused upregulation of NIK and enhanced NC NF-κB downstream signaling. Knockdown or pharmacological inhibition of NIK in TRAF3-deficient cells differentially impaired their proliferation and survival, suggesting an acquired onco-addiction to NC NF-κB. TRAF3 ablation also led to exacerbated secretion of the immunosuppressive cytokine IL-10. Coculturing of TRAF3-deficient DLBCL cells with CD8+ T cells impaired the induction of Granzyme B and interferon (IFN) γ, which were restored following neutralization of IL-10. Our findings corroborate a direct relationship between TRAF3 genetic alterations and NC NF-κB activation, and highlight NIK as a potential therapeutic target in a defined subset of DLBCL.

Relapse Timing Is Associated With Distinct Evolutionary Dynamics in Diffuse Large B-Cell Lymphoma

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) is cured in more than 60% of patients, but outcomes remain poor for patients experiencing disease progression or relapse (refractory or relapsed DLBCL [rrDLBCL]), particularly if these events occur early. Although previous studies examining cohorts of rrDLBCL have identified features that are enriched at relapse, few have directly compared serial biopsies to uncover biological and evolutionary dynamics driving rrDLBCL. Here, we sought to confirm the relationship between relapse timing and outcomes after second-line (immuno)chemotherapy and determine the evolutionary dynamics that underpin that relationship.

PATIENTS AND METHODS

Outcomes were examined in a population-based cohort of 221 patients with DLBCL who experienced progression/relapse after frontline treatment and were treated with second-line (immuno)chemotherapy with an intention-to-treat with autologous stem-cell transplantation (ASCT). Serial DLBCL biopsies from a partially overlapping cohort of 129 patients underwent molecular characterization, including whole-genome or whole-exome sequencing in 73 patients.

RESULTS

Outcomes to second-line therapy and ASCT are superior for late relapse (>2 years postdiagnosis) versus primary refractory (<9 months) or early relapse (9-24 months). Diagnostic and relapse biopsies were mostly concordant for cell-of-origin classification and genetics-based subgroup. Despite this concordance, the number of mutations exclusive to each biopsy increased with time since diagnosis, and late relapses shared few mutations with their diagnostic counterpart, demonstrating a branching evolution pattern. In patients with highly divergent tumors, many of the same genes acquired new mutations independently in each tumor, suggesting that the earliest mutations in a shared precursor cell constrain tumor evolution toward the same genetics-based subgroups at both diagnosis and relapse.

CONCLUSION

These results suggest that late relapses commonly represent genetically distinct and chemotherapy-naïve disease and have implications for optimal patient management.

Genetic subdivisions of follicular lymphoma defined by distinct coding and noncoding mutation patterns

Follicular lymphoma (FL) accounts for ∼20% of all new lymphoma cases. Increases in cytological grade are a feature of the clinical progression of this malignancy, and eventual histologic transformation (HT) to the aggressive diffuse large B-cell lymphoma (DLBCL) occurs in up to 15% of patients. Clinical or genetic features to predict the risk and timing of HT have not been described comprehensively. In this study, we analyzed whole-genome sequencing data from 423 patients to compare the protein coding and noncoding mutation landscapes of untransformed FL, transformed FL, and de novo DLBCL. This revealed 2 genetically distinct subgroups of FL, which we have named DLBCL-like (dFL) and constrained FL (cFL). Each subgroup has distinguishing mutational patterns, aberrant somatic hypermutation rates, and biological and clinical characteristics. We implemented a machine learning-derived classification approach to stratify patients with FL into cFL and dFL subgroups based on their genomic features. Using separate validation cohorts, we demonstrate that cFL status, whether assigned with this full classifier or a single-gene approximation, is associated with a reduced rate of HT. This implies distinct biological features of cFL that constrain its evolution, and we highlight the potential for this classification to predict HT from genetic features present at diagnosis.

Kikuchi-Fujimoto Disease Following COVID-19 Vaccination: Experience at a Population-Based Referral Center

OBJECTIVES

Multiple case reports describe Kikuchi-Fujimoto disease (KFD) following COVID-19 vaccination, but the true nature of this phenomenon is unknown. The purpose of this study was to further assess the relationship between KFD and COVID-19 vaccination at the population level.

METHODS

Confirmed KFD cases from January 2018 to April 2022 were identified from provincial pathology archives and analyzed in the context of vaccination statistics from public health resources.

RESULTS

Our statistical models provide evidence of a temporal association between KFD and both antecedent COVID-19 vaccine administration as well as age-stratified vaccination rates. Eight new cases of plausible COVID-19 vaccine-associated KFD are presented, collectively exhibiting clinical and pathologic features that overlap substantially with those of idiopathic KFD.

CONCLUSIONS

Our findings indicate that KFD is observed in association with COVID-19 vaccination and suggest that mechanistic studies are warranted.

Relapse timing is associated with distinct evolutionary dynamics in DLBCL

Diffuse large B-cell lymphoma (DLBCL) is cured in over 60% of patients, but outcomes are poor for patients with relapsed or refractory disease (rrDLBCL). Here, we performed whole genome/exome sequencing (WGS/WES) on tumors from 73 serially-biopsied patients with rrDLBCL. Based on the observation that outcomes to salvage therapy/autologous stem cell transplantation are related to time-to-relapse, we stratified patients into groups according to relapse timing to explore the relationship to genetic divergence and sensitivity to salvage immunochemotherapy. The degree of mutational divergence increased with time between biopsies, yet tumor pairs were mostly concordant for cell-of-origin, oncogene rearrangement status and genetics-based subgroup. In patients with highly divergent tumors, several genes acquired exclusive mutations independently in each tumor, which, along with concordance of genetics-based subgroups, suggests that the earliest mutations in a shared precursor cell constrain tumor evolution. These results suggest that late relapses commonly represent genetically distinct and chemotherapy-naïve disease.

Diagnostic, Prognostic, and Predictive Role of Next-Generation Sequencing in Mature Lymphoid Neoplasms

Lymphoma is a clinically and biologically heterogeneous disease. Next-generation sequencing (NGS) has expanded our understanding of this heterogeneity at the genetic level, refining disease classification, defining new entities, and providing additional information that can be used in diagnosis and management. This review highlights some of the NGS findings in lymphoma and how they can be used as genetic biomarkers to aid diagnosis and prognosis and guide therapy.

Best Practices in CD30 Immunohistochemistry Testing, Interpretation, and Reporting: An Expert Panel Consensus

CONTEXT.—

Although CD30 testing is an established tool in the diagnostic workup of lymphomas, it is also emerging as a predictive biomarker that informs treatment. The current definition of CD30 positivity by immunohistochemistry is descriptive and based on reactivity in lymphomas that are defined by their universal strong expression of CD30, rather than any established threshold. Challenges include inconsistencies with preanalytic variables, tissue processing, pathologist readout, and with the pathologist and oncologist interpretation of reported results.

OBJECTIVE.—

To develop and propose general best practice recommendations for reporting CD30 expression by immunohistochemistry in lymphoma biopsies to harmonize practices across institutions and facilitate assessment of its significance in clinical decision-making.

DESIGN.—

Following literature review and group discussion, the panel of 14 academic hematopathologists and 2 clinical/academic hematologists/oncologists divided into 3 working groups. Each working group was tasked with assessing CD30 testing by immunohistochemistry, CD30 expression readout, or CD30 expression interpretation.

RESULTS.—

Panel recommendations were reviewed and discussed. An online survey was conducted to confirm the consensus recommendations.

CONCLUSIONS.—

CD30 immunohistochemistry is required for all patients in whom classic Hodgkin lymphoma and any lymphoma within the spectrum of peripheral T-cell lymphoma are differential diagnostic considerations. The panel reinforced and summarized that immunohistochemistry is the preferred methodology and any degree of CD30 expression should be reported. For diagnostic purposes, the interpretation of CD30 expression should follow published guidelines. To inform therapeutic decisions, report estimated percent positive expression in tumor cells (or total cells where applicable) and record descriptively if nontumor cells are positive.

Intraparenchymal Mucosa-Associated Lymphoid Tissue Lymphoma: A Case Report

Marginal zone B-cell lymphoma (MZBCL) of mucosa-associated lymphoid tissue (MALT) type, which is primary to the central nervous system (CNS), is a rare lesion, with those originating within the parenchyma even more so. We present the case of a 64-year-old male with weakness in the left hand and focal motor seizures of his arm, who was found to have a right frontal intraparenchymal lesion. Following resection, histopathological and immunohistochemical evaluations were completed, leading to a diagnosis of a primary CNS MZBCL of MALT type in the context of a negative workup of systemic disease. Neuroimaging, histopathological, and immunohistochemical findings, as well as a comprehensive literature review of similar cases, are discussed.

Clinicopathological characteristics and long-term outcomes of plasmablastic lymphoma in British Columbia

Plasmablastic lymphoma (PBL) is an aggressive and rare subtype of non-Hodgkin lymphoma with no standard-of-care therapy. We reviewed all patients diagnosed with histologically confirmed PBL in British Columbia, Canada between 1997 and 2019. Overall, 42 patients were identified, including 15 (36%) positive for HIV and nine (21%) on chronic immunosuppression. Curative-intent treatment consisting primarily of cyclophosphamide, doxorubicin, vincristine and prednisone was administered to 31 patients, of which 74% achieved response, however 61% relapsed after a median of 7.5 months. At a median follow-up of eight years for the whole cohort, five-year progression-free survival (PFS) and overall survival (OS) were 18% [95% confidence interval (CI): 6%, 30%] and 22% (95% CI: 8%, 36%) with median eight and 15 months respectively. There were no differences in relapse rate (p = 0.962), PFS (p = 0.228) or OS (p = 0.340) according to immune status. For those treated with curative intent, five-year PFS and OS were 24% (95% CI: 8%, 40%) and 31% (95% CI: 13%, 49%) with median 18 and 27 months respectively. In this population-based cohort of PBL patients spanning 20 years, survival outcomes were poor. Ultimately, further research is needed to develop more effective treatment strategies and to improve survival for patients.

BCL10 Mutations Define Distinct Dependencies Guiding Precision Therapy for DLBCL

Activated B cell-like diffuse large B-cell lymphomas (ABC-DLBCL) have unfavorable outcomes and chronic activation of CARD11-BCL10-MALT1 (CBM) signal amplification complexes that form due to polymerization of BCL10 subunits, which is affected by recurrent somatic mutations in ABC-DLBCLs. Herein, we show that BCL10 mutants fall into at least two functionally distinct classes: missense mutations of the BCL10 CARD domain and truncation of its C-terminal tail. Truncating mutations abrogated a motif through which MALT1 inhibits BCL10 polymerization, trapping MALT1 in its activated filament-bound state. CARD missense mutations enhanced BCL10 filament formation, forming glutamine network structures that stabilize BCL10 filaments. Mutant forms of BCL10 were less dependent on upstream CARD11 activation and thus manifested resistance to BTK inhibitors, whereas BCL10 truncating but not CARD mutants were hypersensitive to MALT1 inhibitors. Therefore, BCL10 mutations are potential biomarkers for BTK inhibitor resistance in ABC-DLBCL, and further precision can be achieved by selecting therapy based on specific biochemical effects of distinct mutation classes.

SIGNIFICANCE

ABC-DLBCLs feature frequent mutations of signaling mediators that converge on the CBM complex. We use structure-function approaches to reveal that BCL10 mutations fall into two distinct biochemical classes. Both classes confer resistance to BTK inhibitors, whereas BCL10 truncations confer hyperresponsiveness to MALT1 inhibitors, providing a road map for precision therapies in ABC-DLBCLs. See related commentary by Phelan and Oellerich, p. 1844. This article is highlighted in the In This Issue feature, p. 1825.

A 54-Year-Old Woman with Cutaneous Nodules

A 54-Year-Old Woman with Cutaneous NodulesA 54-year-old woman presented with chronic cutaneous nodules and plaques. How do you approach the evaluation, and what is the diagnosis?

Immune Escape Mechanisms in Intravascular Large B-Cell Lymphoma: A Molecular Cytogenetic and Immunohistochemical Study

OBJECTIVES

Intravascular large B-cell lymphomas (IVLBCLs) are rare extranodal LBCLs in which relapse is relatively frequent. We sought to further characterize potential immune escape mechanisms in IVLBCLs that newer therapies can exploit.

METHODS

A series of 33 IVLBCLs were evaluated for programmed cell death ligand 1 (PD-L1) and PD-L2 expression by immunohistochemistry (IHC), chromosomal alterations (CAs) in the PDL1/PDL2 locus by fluorescence in situ hybridization, and loss of major histocompatibility complex (MHC) class I and II expression by IHC.

RESULTS

Cases were subclassified as classical (n = 22) or hemophagocytic syndrome (HPS)-associated (n = 11) variants. A total of 12 cases (39%; n = 12/31) expressed PD-L1 and/or PD-L2. CAs were seen in 7 cases (7/29 [24%]) and included gains, amplifications, and rearrangements. CAs in classical variant cases (24%; n = 5/21) included gains (n =1), gains with concurrent rearrangements (n = 2), and amplifications (n = 2). The 2 HPS-associated variant cases with CAs (25%; n = 2/8) both showed amplification, including 1 case with a concurrent rearrangement. A majority of cases with CAs (71%; n = 5/7) were PD-L1/PD-L2 IHC positive. Among PD-L1/PD-L2 IHC-positive cases, 45% harbored a CA. Loss of MHC class I and/or class II was seen in 27% (n = 9/33) of cases.

CONCLUSIONS

Altogether, our data show that 65% (n = 20/31) of IVLBCLs may exploit immune evasion strategies through PD-L1/PD-L2 expression or downregulation of MHC proteins.

Genome-Wide miRNA Expression Profiling of Molecular Subgroups of Peripheral T-cell Lymphoma

PURPOSE

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of non-Hodgkin lymphomas with aggressive clinical behavior. We performed comprehensive miRNA profiling in PTCLs and corresponding normal CD4⁺ Th1/2 and TFH-like polarized subsets to elucidate the role of miRNAs in T-cell lymphomagenesis.

EXPERIMENTAL DESIGN

We used nCounter (NanoString Inc) for miRNA profiling and validated using Taqman qRT-PCR (Applied Biosystems, Inc). Normal CD4⁺ T cells were polarized into effector Th subsets using signature cytokines, and miRNA significance was revealed using functional experiments.

RESULTS

Effector Th subsets showed distinct miRNA expression with corresponding transcription factor expression (e.g., BCL6/miR-19b, -106, -30d, -26b, in IL21-polarized; GATA3/miR-155, miR-337 in Th2-polarized; and TBX21/miR-181a, -331-3p in Th1-polarized cells). Integration of miRNA signatures suggested activation of TCR and PI3K signaling in IL21-polarized cells, ERK signaling in Th1-polarized cells, and AKT-mTOR signaling in Th2-polarized cells, validated at protein level. In neoplastic counterparts, distinctive miRNAs were identified and confirmed in an independent cohort. Integrative miRNA-mRNA analysis identified a decrease in target transcript abundance leading to deregulation of sphingolipid and Wnt signaling and epigenetic dysregulation in angioimmunoblastic T-cell lymphoma (AITL), while ERK, MAPK, and cell cycle were identified in PTCL subsets, and decreased target transcript abundance was validated in an independent cohort. Elevated expression of miRNAs (miR-126-3p, miR-145-5p) in AITL was associated with poor clinical outcome. In silico and experimental validation suggest two targets (miR-126→ SIPR2 and miR-145 → ROCK1) resulting in reduced RhoA-GTPase activity and T-B-cell interaction.

CONCLUSIONS

Unique miRNAs and deregulated oncogenic pathways are associated with PTCL subtypes. Upregulated miRNA-126-3p and miR-145-5p expression regulate RhoA-GTPase and inhibit T-cell migration, crucial for AITL pathobiology.

Characterisation of immune checkpoints in Richter syndrome identifies LAG3 as a potential therapeutic target

Richter syndrome (RS), an aggressive lymphoma occurring in the context of chronic lymphocytic leukaemia/small lymphocytic lymphoma, is associated with poor prognosis when treated with conventional immunochemotherapy, therefore, improved treatments are required. Immune checkpoint blockade has shown efficacy in some B-cell malignancies and modest responses in early clinical trials for RS. We investigated the immune checkpoint profile of RS as a basis to inform rational therapeutic investigations in RS. Formalin-fixed, paraffin-embedded biopsies of RS (n = 19), de novo diffuse large B-cell lymphoma (DLBCL; n = 58), transformed indolent lymphomas (follicular [tFL], n = 16; marginal zone [tMZL], n = 24) and non-transformed small lymphocytic lymphoma (SLL; n = 15) underwent gene expression profiling using the NanoString Human Immunology panel. Copy number assessment was performed using next-generation sequencing. Immunohistochemistry (IHC) for LAG3 and PD-1 was performed. LAG3 gene expression was higher in RS compared to DLBCL (P = 0·0002, log2FC 1·96), tFL (P < 0·0001, log2FC 2·61), tMZL (P = 0·0004, log2FC 1·79) and SLL (P = 0·0057, log2FC 1·45). LAG3 gene expression correlated with the gene expression of human leukocyte antigen Class I and II, and related immune genes and immune checkpoints. IHC revealed LAG3 protein expression on both malignant RS cells and tumour-infiltrating lymphocytes. Our findings support the investigation of LAG3 inhibition to enhance anti-tumour responses in RS.

Prognostic significance of FCGR2B expression for the response of DLBCL patients to rituximab or obinutuzumab treatment

Fc γ receptor IIB (FcγRIIB) is an inhibitory molecule capable of reducing antibody immunotherapy efficacy. We hypothesized its expression could confer resistance in patients with diffuse large B-cell lymphoma (DLBCL) treated with anti-CD20 monoclonal antibody (mAb) chemoimmunotherapy, with outcomes varying depending on mAb (rituximab [R]/obinutuzumab [G]) because of different mechanisms of action. We evaluated correlates between FCGR2B messenger RNA and/or FcγRIIB protein expression and outcomes in 3 de novo DLBCL discovery cohorts treated with R plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) reported by Arthur, Schmitz, and Reddy, and R-CHOP/G-CHOP-treated patients in the GOYA trial (NCT01287741). In the discovery cohorts, higher FCGR2B expression was associated with significantly shorter progression-free survival (PFS; Arthur: hazard ratio [HR], 1.09; 95% confidence interval [CI], 1.01-1.19; P = .0360; Schmitz: HR, 1.13; 95% CI, 1.02-1.26; P = .0243). Similar results were observed in GOYA with R-CHOP (HR, 1.26; 95% CI, 1.00-1.58; P = .0455), but not G-CHOP (HR, 0.91; 95% CI, 0.69-1.20; P = .50). A nonsignificant trend that high FCGR2B expression favored G-CHOP over R-CHOP was observed (HR, 0.67; 95% CI, 0.44-1.02; P = .0622); however, low FCGR2B expression favored R-CHOP (HR, 1.58; 95% CI, 1.00-2.50; P = .0503). In Arthur and GOYA, FCGR2B expression was associated with tumor FcγRIIB expression; correlating with shorter PFS for R-CHOP (HR, 2.17; 95% CI, 1.04-4.50; P = .0378), but not G-CHOP (HR, 1.37; 95% CI, 0.66-2.87; P = .3997). This effect was independent of established prognostic biomarkers. High FcγRIIB/FCGR2B expression has prognostic value in R-treated patients with DLBCL and may confer differential responsiveness to R-CHOP/G-CHOP.

Abstract PO-26: Prognostic significance of Fc gamma receptor IIB expression in the response of previously untreated diffuse large B-cell lymphomas to anti-CD20 monoclonal antibodies: Differing impact of rituximab and obinutuzumab

Background: The anti-CD20 monoclonal antibody (mAb), obinutuzumab (G), has shown improved outcomes versus rituximab (R) in indolent lymphomas; however, no improvement was seen in diffuse large B-cell lymphoma (DLBCL), and the molecular basis is unclear. The inhibitory Fc gamma receptor IIB (Fc γRIIB), expressed on lymphoma cells, can impair the effects of direct targeting mAbs, such as R, by binding and internalizing them, reducing opsonization and limiting FcγR-mediated killing. We hypothesized that FcγRIIB expression on cellular effectors and/or the lymphoma confers treatment resistance in some patients (pts) and evaluated if outcomes differ for therapies involving a non-internalized mAb (G).

Methods: We evaluated correlates between FCGR2B mRNA and/or FcγRIIB protein expression and pt outcomes in two discovery cohorts of de novo DLBCL treated with R-CHOP (Arthur et al. 2018, n=372; Schmitz et al. 2018, n=234), and the phase III GOYA trial (NCT01287741; n=552), which compared R-CHOP with G-CHOP in pts with previously untreated DLBCL. FCGR2B mRNA expression was assessed by RNA-Seq, and protein expression was assessed in evaluable cohorts by immunohistochemistry, using tissue microarrays with macrophages identified by CD68. FCGR2B expression was also measured by a NanoString assay (Arthur cohort). Cox regression analyzed the impact of FcγRIIB/FCGR2B expression on progression-free survival (PFS), with univariate and multivariate models adjusted for International Prognostic Index (IPI), cell of origin (COO), and BCL2 protein expression.

Results: In the discovery cohorts, a higher FCGR2B expression was significantly associated with shorter PFS (Arthur: HR 1.09 [95% CI: 1.01–1.19], P=0.036; Schmitz: HR 1.13 [95% CI: 1.02–1.26], P=0.0243). Expression by NanoString strongly correlated with RNA-Seq, confirming the association with shorter PFS (HR 1.13 [95% CI: 1.04–1.23], P=0.0048). In GOYA, a significant association between PFS and FCGR2B was observed in the R arm (HR 1.26 [95% CI: 1.00–1.58], P=0.0455), with no prognostic effect observed for G (HR 0.91 [95% CI: 0.69–1.20], P=0.5). Pts with high FCGR2B expression appeared to benefit more from G than R (HR 0.67 [95% CI: 0.44–1.02], P=0.0622), in contrast to pts with low FCGR2B expression (HR 1.58 [95% CI: 1.00–2.50], P=0.0503). In both Arthur and GOYA cohorts, FCGR2B expression by RNA-Seq was associated with FcγRIIB on the tumor, which correlated with a shorter PFS for R (HR 2.17 [95% CI: 1.04–4.50], P=0.03), but not G (HR 1.37 [95% CI: 0.66–2.87], P=0.4). This prognostic effect on PFS was independent of established prognostic biomarkers, IPI, COO and BCL2.

Conclusion: High FcγRIIB/FCGR2B expression in pts with DLBCL has prognostic value in those treated with R and may confer differential responsiveness to R or G.

Citation Format: Laura K. Hilton, Malgorzata Nowicka, Margaret Ashton-Key, Chantal E. Hargreaves, Chern Lee, Russell Foxall, Matthew J. Carter, Stephen A. Beers, Kathleen N. Potter, Christopher R. Bolen, Christian Klein, Andrea Knapp, Farheen Mir, Matthew Rose-Zerilli, Cathy Burton, Wolfram Klapper, David W. Scott, Laurie H. Sehn, Umberto Vitolo, Maurizio Martelli, Marek Trneny, Graham W. Slack, Pedro Farinha, Jonathan C. Strefford, Mikkel Z. Oestergaard, Ryan D. Morin, Mark S. Cragg. Prognostic significance of Fc gamma receptor IIB expression in the response of previously untreated diffuse large B-cell lymphomas to anti-CD20 monoclonal antibodies: Differing impact of rituximab and obinutuzumab [abstract]. In: Proceedings of the AACR Virtual Meeting: Advances in Malignant Lymphoma; 2020 Aug 17-19. Philadelphia (PA): AACR; Blood Cancer Discov 2020;1(3_Suppl):Abstract nr PO-26.

Coding and noncoding drivers of mantle cell lymphoma identified through exome and genome sequencing

Mantle cell lymphoma (MCL) is an uncommon B-cell non-Hodgkin lymphoma (NHL) that is incurable with standard therapies. The genetic drivers of this cancer have not been firmly established, and the features that contribute to differences in clinical course remain limited. To extend our understanding of the biological pathways involved in this malignancy, we performed a large-scale genomic analysis of MCL using data from 51 exomes and 34 genomes alongside previously published exome cohorts. To confirm our findings, we resequenced the genes identified in the exome cohort in 191 MCL tumors, each having clinical follow-up data. We confirmed the prognostic association of TP53 and NOTCH1 mutations. Our sequencing revealed novel recurrent noncoding mutations surrounding a single exon of the HNRNPH1gene. In RNA-seq data from 103 of these cases, MCL tumors with these mutations had a distinct imbalance of HNRNPH1 isoforms. This altered splicing of HNRNPH1 was associated with inferior outcomes in MCL and showed a significant increase in protein expression by immunohistochemistry. We describe a functional role for these recurrent noncoding mutations in disrupting an autoregulatory feedback mechanism, thereby deregulating HNRNPH1 protein expression. Taken together, these data strongly imply a role for aberrant regulation of messenger RNA processing in MCL pathobiology.

Gene expression profiling of gray zone lymphoma

Gray zone lymphoma (GZL), a B-cell lymphoma with features intermediate between large B-cell lymphoma (LBCL) and classic Hodgkin lymphoma (cHL), is a rare and poorly defined entity. Alongside GZL, a subset of Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) has been described with polymorphic/GZL-like morphology (polymorphic-EBV-L). To fill the important gap in our understanding of the pathogenic process underlying these entities, we performed a gene expression study of a large international cohort of GZL and polymorphic-EBV-L, combined with cHL and primary mediastinal large B-cell lymphoma (PMBCL) cases. In an unsupervised principal component analysis, GZL cases presented with intermediate scores in a spectrum between cHL and PMBCL, whereas polymorphic-EBV-L clustered distinctly. The main biological pathways underlying the GZL spectrum were related to cell cycle, reflecting tumor cell content, and extracellular matrix signatures related to the cellular tumor microenvironment. Differential expression analysis and phenotypic characterization of the tumor microenvironment highlighted the predominance of regulatory macrophages in GZL compared with cHL and PMBCL. Two distinct subtypes of GZL were distinguishable that were phenotypically reminiscent of PMBCL and DLBCL, and we observed an association of PMBCL-type GZL with clinical presentation in the "thymic" anatomic niche. In summary, gene expression profiling (GEP) enabled us to add precision to the GZL spectrum, describe the biological distinction compared with polymorphic-EBV-L, and distinguish cases with and without thymic involvement as 2 subgroups of GZL, namely PMBCL-like and DLBCL-like GZL.

Outcome of elderly patients with classical Hodgkin lymphoma (HL) in British Columbia

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Background: Outcomes in elderly patients (pts) with Hodgkin lymphoma (HL) have traditionally been poor. We evaluated the survival of elderly pts (>60 years [y]) with classical HL in British Columbia (BC). Methods: All pts aged >60 y newly diagnosed with classical HL from 1961 to 2019 were identified in the BC Cancer Lymphoid Cancer Database. Limited stage was defined as non-bulky (<10 cm) stage 1A/IB or 2A (before 2000 1B = advanced stage), with the remainder considered advanced stage. Results: Following exclusions (HIV positive n=4, incomplete data n=21, prior or concurrent other lymphoproliferative disease n=67), 713 pts were identified. With a median follow up of 6.0 y (0.1 - 24.0 y) in living pts, there has been an improvement in 5 y DSS/OS (both p<.001) by decade comparison: 1960s (n=52) 25%/17%; 1970s (n=75) 38%/31%; 1980s (n=90) 51%/43%; 1990s (n=115) 53%/42%; 2000s (n=180) 66%/57%; 2010s (n=201) 63%/53%. To account for advances in diagnosis, staging, supportive care, and therapy in the modern era, we evaluated the outcome of pts diagnosed since 01/1995. A total of 368 pts were treated with curative intent (Table). Most pts received multi-agent chemotherapy (n=359, 98%: ABVD[like] n=351, alkylator-based n=7, CHOP n=1), 8 pts had radiotherapy (RT) alone, and 1 pt had surgery (primary CNS HL). The 5 y DSS, PFS, and OS were 74%, 57%, and 62%, respectively. Increasing age was associated with inferior outcomes (5 y DSS/PFS/OS): 61-70 y (81%/70%/74%), 71-80 y (69%/47%/52%), and >80 y (59%/27%/31%) (DSS p=.011; PFS p<.0001; OS p<.0001). Of 318 pts that received bleomycin, 60 (19%) developed pulmonary toxicity, including 22 cases that occurred after cycles 1 and 2. Overall, 24/368 pts (7%) died of acute treatment toxicity (pulmonary [bleomycin n=10, radiation n=1], infection n=10, cardiac n=3). There was no association between age and developing bleomycin (p=.80) or lethal treatment toxicities (p=.74). Conclusions: The outcome of elderly pts with HL has improved in recent decades. However, treatment related toxicity remains a concern and use of multi-agent chemotherapy, particularly bleomycin-containing regimens, should be undertaken with caution. [Table: see text]

Validation of a simplified international prognostic score (IPS-3) in patients with advanced-stage classic Hodgkin lymphoma

A novel prognostic score (IPS-3), comprised of only three of the seven IPS-7 indicators (age ≥45, stage IV, haemoglobin <105 g/l), was recently proposed as a simplified model for advanced-stage classic Hodgkin lymphoma (cHL). We aimed to validate this model in advanced-stage cHL patients treated with doxorubicin, bleomycin, vinblastine, dacarbazine (ABVD) in British Columbia. The estimated five-year freedom from progression (FFP) for scores of 0, 1, 2 and 3 were very similar to the original report at 84%, 76%, 72% and 68% respectively. The IPS-3 score is highly reproducible in this independent dataset and its simplicity makes it appealing for everyday clinical practice.

Single Cell Phenotypic Profiling of 27 DLBCL Cases Reveals Marked Intertumoral and Intratumoral Heterogeneity

Diffuse large B-cell lymphoma (DLBCL) is the most common histologic subtype of non-Hodgkin lymphoma and is notorious for its clinical heterogeneity. Patient outcomes can be predicted by cell-of-origin (COO) classification, demonstrating that the underlying transcriptional signature of malignant B-cells informs biological behavior in the context of standard combination chemotherapy regimens. In the current study, we used mass cytometry (CyTOF) to examine tumor phenotypes at the protein level with single cell resolution in a collection of 27 diagnostic DLBCL biopsy specimens from treatment naïve patients. We found that malignant B-cells from each patient occupied unique regions in 37-dimensional phenotypic space with no apparent clustering of samples into discrete subtypes. Interestingly, variable MHC class II expression was found to be the greatest contributor to phenotypic diversity. Within individual tumors, a subset of cases showed multiple phenotypic subpopulations, and in one case, we were able to demonstrate direct correspondence between protein-level phenotypic subsets and DNA mutation-defined subclones. In summary, CyTOF analysis can resolve both intertumoral and intratumoral heterogeneity among primary samples and reveals that each case of DLBCL is unique and may be comprised of multiple, genetically distinct subclones. © 2019 International Society for Advancement of Cytometry.

Double-Hit Gene Expression Signature Defines a Distinct Subgroup of Germinal Center B-Cell-Like Diffuse Large B-Cell Lymphoma

PURPOSE

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL-DH/TH) has a poor outcome after standard chemoimmunotherapy. We sought to understand the biologic underpinnings of HGBL-DH/TH with BCL2 rearrangements (HGBL-DH/TH- BCL2) and diffuse large B-cell lymphoma (DLBCL) morphology through examination of gene expression.

PATIENTS AND METHODS

We analyzed RNA sequencing data from 157 de novo germinal center B-cell-like (GCB)-DLBCLs, including 25 with HGBL-DH/TH- BCL2, to define a gene expression signature that distinguishes HGBL-DH/TH- BCL2 from other GCB-DLBCLs. To assess the genetic, molecular, and phenotypic features associated with this signature, we analyzed targeted resequencing, whole-exome sequencing, RNA sequencing, and immunohistochemistry data.

RESULTS

We developed a 104-gene double-hit signature (DHITsig) that assigned 27% of GCB-DLBCLs to the DHITsig-positive group, with only one half harboring MYC and BCL2 rearrangements (HGBL-DH/TH- BCL2). DHITsig-positive patients had inferior outcomes after rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone immunochemotherapy compared with DHITsig-negative patients (5-year time to progression rate, 57% and 81%, respectively; P < .001), irrespective of HGBL-DH/TH- BCL2 status. The prognostic value of DHITsig was confirmed in an independent validation cohort. DHITsig-positive tumors are biologically characterized by a putative non-light zone germinal center cell of origin and a distinct mutational landscape that comprises genes associated with chromatin modification. A new NanoString assay (DLBCL90) recapitulated the prognostic significance and RNA sequencing assignments. Validating the association with HGBL-DH/TH- BCL2, 11 of 25 DHITsig-positive-transformed follicular lymphomas were classified as HGBL-DH/TH- BCL2 compared with zero of 50 in the DHITsig-negative group. Furthermore, the DHITsig was shared with the majority of B-cell lymphomas with high-grade morphology tested.

CONCLUSION

We have defined a clinically and biologically distinct subgroup of tumors within GCB-DLBCL characterized by a gene expression signature of HGBL-DH/TH- BCL2. This knowledge has been translated into an assay applicable to routinely available biopsy samples, which enables exploration of its utility to guide patient management.

A young woman with steroid-responsive, IgG4-positive plasma cell-enriched cystic lymphangioma and chylous ascites

Lymphangiomas are benign tumors of the lymphatic vessels, which can be inflammatory and occasionally steroid-responsive. IgG4-related disease (IgG4-RD) is a recently defined fibro-inflammatory condition. We describe a novel association between reactive IgG4+ plasma cells and cystic lymphangioma in a young woman who had a dramatic clinical response to steroids.

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements with diffuse large B-cell lymphoma morphology

High-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements (HGBL-DH/TH) is a newly defined entity in the latest World Health Organization Classification. Accurate diagnosis would appear to mandate fluorescence in situ hybridization (FISH) for all tumors with diffuse large B-cell lymphoma (DLBCL) morphology. We present the results of FISH, cell-of-origin, and immunohistochemistry (IHC) testing from 1228 DLBCL biopsies from 3 clinical trials and a population-based registry. HGBL-DH/TH made up 7.9% of the DLBCL, confined primarily to the germinal center B-cell-like (GCB; 13.3%) compared with activated B-cell-like (ABC; 1.7%) subtype (P < .001). HGBL-DH/TH with BCL2 rearrangement is a GCB phenomenon with no cases observed in 415 ABC DLBCL. A screening strategy restricting FISH testing to tumors of GCB subtype (by Lymph2Cx or Hans IHC) plus dual protein expression of MYC and BCL2 by IHC could limit testing to 11% to 14% of tumors, with a positive predictive value of 30% to 37%; however, this strategy would miss approximately one-quarter of tumors with HBGL-DH/TH with BCL2 rearrangement and one-third of all HGBL-DH/TH. These results provide accurate estimation of the proportion of HGBL-DH/TH among tumors with DLBCL morphology and allow determination of the impact of various methods available to screen DLBCL tumors for FISH testing.

International Assessment of Event-Free Survival at 24 Months and Subsequent Survival in Peripheral T-Cell Lymphoma

Purpose Peripheral T-cell lymphomas (PTCLs) have aggressive clinical behavior. We have previously shown that event-free survival (EFS) at 24 months (EFS24) is a clinically useful end point in diffuse large B-cell lymphoma. Here, we assess EFS24 and subsequent overall survival (OS) in large, multinational PTCL cohorts. Patients and Methods Patients with systemic PTCL newly diagnosed from 2000 to 2012 and treated with curative intent were included from the United States and Sweden (initial cohorts) and from Canada (replication cohort). EFS was defined as time from date of diagnosis to progression after primary treatment, retreatment, or death. Subsequent OS was measured after achieving EFS24 or from the time of progression if it occurred within 24 months. OS rates were compared with the age-, sex-, and country-matched general population. Results Seven hundred seventy-five patients were included in the study (the median age at diagnosis was 64 years; 63% were men). Results were similar in the initial and replication cohorts, and a combined analysis was undertaken. Sixty-four percent of patients progressed within the first 24 months and had a median OS of only 4.9 months (5-year OS, 11%). In contrast, median OS after achieving EFS24 was not reached (5-year OS, 78%), although relapses within 5 years of achieving EFS24 occurred in 23% of patients. Superior outcomes after achieving EFS24 were observed in younger patients (≤ 60 years of age: 5-year OS, 91%). Conclusion EFS24 stratifies subsequent outcome in PTCL. Patients with PTCL with primary refractory disease or early relapse have extremely poor survival. However, more than one third of patients with PTCL remain in remission 2 years after diagnosis with encouraging subsequent OS, especially in younger patients. These marked differences in outcome suggest that EFS24 has utility for patient counseling, study design, and risk stratification in PTCL.

Utility of Serum IgG4 Levels in a Multiethnic Population

BACKGROUND

IgG4-related disease (IgG4-RD) is a recently recognized condition defined by characteristic histopathologic findings in affected organs. Serum IgG4 concentration is often but not always elevated. The sensitivity and specificity of serum IgG4 vary greatly across studies and has been anecdotally associated to ethnicity. Our study was conducted to investigate the difference in serum IgG4 levels between Asian and non-Asian patients with IgG4-RD.

METHODS

This is a single-center retrospective study of 26 Asian and 10 non-Asian patients with histologically confirmed IgG4-RD. Serum IgG4 levels, clinical features and other laboratory findings were compared between the 2 groups, 31 Asian and 11 non-Asian patients with non-IgG4-RD rheumatic diseases were randomly identified to evaluate test characteristics of serum IgG4 measurement.

RESULTS

Median serum IgG4 at time of diagnosis was significantly higher in Asian (median = 11.2g/L, interquartile range: 4.6-19.7) than non-Asian patients (median = 2.9g/L, interquartile range: 0.7-5.4, P = 0.0094), as well as the median serum IgG and total protein. Asian patients had more eosinophilia and polyclonal hypergammaglobulinemia than non-Asian patients (P = 0.016 and 0.001, respectively). Test sensitivity was higher in Asian (96%) than non-Asian patients (67%), whereas test specificity was higher in non-Asian patients (91% versus 71%).

CONCLUSION

Asian patients with IgG4-RD have more exuberant serum IgG4, IgG and polyclonal hypergammaglobulinemia than non-Asian patients; the mechanism of this difference requires further study. These findings have significant clinical importance and must be accounted for in the diagnostic workup of patients in multiethnic settings.

A Phase 2/3 Multicenter, Randomized, Open-Label Study to Compare the Efficacy and Safety of Lenalidomide Versus Investigator's Choice in Patients with Relapsed or Refractory Diffuse Large B-Cell Lymphoma

Purpose: Randomized, multicenter, open-label, phase 2/3 trial investigating lenalidomide versus investigator's choice (IC) in relapsed/refractory diffuse large B-cell lymphoma (DLBCL).Experimental Design: Patients with DLBCL who received ≥2 prior therapies were stratified by DLBCL subtype [germinal center B-cell (GCB) vs. non-GCB; determined by immunohistochemistry (IHC)] and then randomized 1:1 to lenalidomide (25 mg/day, 21 days of 28-day cycle) or IC (gemcitabine, rituximab, etoposide, or oxaliplatin). Crossover to lenalidomide was permitted for IC-treated patients with radiologically confirmed progressive disease. The primary endpoint was overall response rate (ORR). Progression-free survival (PFS), overall survival, and subtype analysis [GCB vs. activated B-cell (ABC)] using gene expression profiling (GEP) were exploratory endpoints.Results: Stage 1: 102 DLBCL patients (by IHC: non-GCB, n = 54; GCB, n = 48) received ≥1 dose of lenalidomide or IC. Hematologic treatment-emergent adverse events with lenalidomide versus IC included neutropenia (42.6%; 36.4%), anemia (33.3%; 47.3%), thrombocytopenia (24.1%; 43.6%), and leukopenia (5.6%; 12.7%), respectively. Overall, lenalidomide-treated patients had an ORR of 27.5% versus 11.8% in IC (ORRs were similar regardless of IHC-defined DLBCL subtype). Median PFS was increased in patients receiving lenalidomide (13.6 weeks) versus IC (7.9 weeks; P = 0.041), with greater improvements in non-GCB patients (15.1 vs. 7.1 weeks, respectively; P = 0.021) compared with GCB (10.1 vs. 9.0 weeks, respectively; P = 0.550).Conclusions: The clinical benefit of lenalidomide monotherapy in DLBCL patients was more evident in the non-GCB subtype. Exploratory analyses suggest that this preferential benefit was more pronounced in the GEP-defined ABC population, demonstrating a need for additional studies of lenalidomide in DLBCL using GEP subtyping. Clin Cancer Res; 23(15); 4127-37. ©2017 AACR.

New Molecular Assay for the Proliferation Signature in Mantle Cell Lymphoma Applicable to Formalin-Fixed Paraffin-Embedded Biopsies

Purpose Mantle cell lymphoma is an aggressive B-cell neoplasm that displays heterogeneous outcomes after treatment. In 2003, the Lymphoma/Leukemia Molecular Profiling Project described a powerful biomarker-the proliferation signature-using gene expression in fresh frozen material. Herein, we describe the training and validation of a new assay that measures the proliferation signature in RNA derived from routinely available formalin-fixed paraffin-embedded (FFPE) biopsies. Methods Forty-seven FFPE biopsies were used to train an assay on the NanoString platform, using microarray gene expression data of matched fresh frozen biopsies as a gold standard. The locked assay was applied to pretreatment FFPE lymph node biopsies from an independent cohort of 110 patients uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone. Seventeen biopsies were tested across three laboratories to assess assay reproducibility. Results The MCL35 assay, which contained a 17-gene proliferation signature, yielded gene expression of sufficient quality to assign an assay score and risk group in 108 (98%) of 110 archival FFPE biopsies. The MCL35 assay assigned patients to high-risk (26%), standard-risk (29%), and low-risk (45%) groups, with different lengths of overall survival (OS): a median of 1.1, 2.6, and 8.6 years, respectively (log-rank for trend, P < .001). In multivariable analysis, these risk groups and the Mantle Cell Lymphoma International Prognostic Index were independently associated with OS ( P < .001 for both variables). Concordance of risk assignment across the three independent laboratories was 100%. Conclusion The newly developed and validated MCL35 assay for FFPE biopsies uses the proliferation signature to define groups of patients with significantly different OS independent of the Mantle Cell Lymphoma International Prognostic Index. Importantly, the analytic and clinical validity of this assay defines it as a reliable biomarker to support risk-adapted clinical trials.

Nonrandom occurrence of lymphoid cancer types in 140 families

We studied 140 families with two or more lymphoid cancers, including non-Hodgkin lymphoma (NHL), Hodgkin lymphoma (HL), chronic lymphocytic leukemia (CLL), and multiple myeloma (MM), for deviation from the population age of onset and lymphoid cancer co-occurrence patterns. Median familial NHL, HL, CLL and MM ages of onset are substantially earlier than comparable population data. NHL, HL and CLL (but not MM) also show earlier age of onset in later generations, known as anticipation. The co-occurrence of lymphoid cancers is significantly different from that expected based on population frequencies (p < .0001), and the pattern differs more in families with more affected members (p < .0001), suggesting specific lymphoid cancer combinations have a shared genetic basis. These families provide evidence for inherited factors that increase the risk of multiple lymphoid cancers. This study was approved by the BC Cancer Agency - University of British Columbia Clinical Research Ethics Board.

The Pathology of Reactive Lymphadenopathies: A Discussion of Common Reactive Patterns and Their Malignant Mimics

Context.—Distinguishing between a reactive and a neoplastic lymphoid proliferation is a clinically significant task frequently performed by the surgical pathologist in routine practice.

Objectives.—To highlight common situations in lymph node pathology where reactive changes and lymphoma may be misdiagnosed.

Data Sources.—Data sources are peer-reviewed journal articles, textbooks, and clinical experience.

Conclusions.—This review aims to refresh and enhance the surgical pathologist's awareness of the shared and distinguishing features of select reactive and neoplastic lymphoproliferations, which in turn will allow the surgical pathologist to make more accurate diagnoses and avoid the pitfalls of misdiagnosis. This will be done by describing a selection of commonly encountered reactive histologic changes observed in lymph nodes, present the lymphomas with which they share overlapping features, outline the features that distinguish them, and describe an approach to making an accurate diagnosis and avoiding a misdiagnosis in each scenario.

Evaluation of the Risk of Relapse in Classical Hodgkin Lymphoma at Event-Free Survival Time Points and Survival Comparison With the General Population in British Columbia

Purpose

Studies in classical Hodgkin lymphoma (cHL) typically measure the time to events from diagnosis. We evaluated the risk of relapse at event-free survival time points in cHL and compared the risk of death to expected mortality rates in British Columbia (BC).

Methods

The BC Cancer Agency Lymphoid Cancer Database was screened to identify all patients age 16 to 69 years diagnosed with cHL between 1989 and 2012 treated with the chemotherapy regimen of doxorubicin, bleomycin, vinblastine, and dacarbazine (or equivalent). We compared the observed mortality to the general population using age-, sex-, and calendar period–generated expected mortality rates from BC life-tables. Relative survival was calculated using a conditional approach and expressed as a standardized mortality ratio of observed-to-expected deaths.

Results

One thousand four hundred two patients were identified; 749 patients were male (53%), the median age was 32 years, and 68% had advanced-stage disease. The median follow-up time was 8.4 years. Seventy-two percent of relapses occurred within the first 2 years of diagnosis. For all patients, the 5-year risk of relapse from diagnosis was 18.1% but diminished to 5.6% for patients remaining event free at 2 years. For advanced-stage patients who were event free at 2 years, the 5-year risk of relapse was only 7.6%, and for those who were event free at 3 years, it was comparable to that of limited-stage patients (4.1% v 2.5%, respectively; P = .07). Furthermore, international prognostic score ≥ 4 and bulky disease were no longer prognostic in patients who were event free at 1 year. Although the relative survival improved as patients remained in remission, it did not normalize compared with the general population.

Conclusion

Patients with cHL who are event free at 2 years have an excellent outcome regardless of baseline prognostic factors. All patients with cHL had an enduring increased risk of death compared with the general population.