[Show abstract][Hide abstract] ABSTRACT: Primary mediastinal large B cell lymphoma (PMBCL) is an aggressive non-Hodgkin's lymphoma, predominantly affecting young patients. We analyzed 45 primary PMBCL tumor biopsies and 3 PMBCL-derived cell lines for the presence of genetic alterations involving the major histocompatibility complex (MHC) class II transactivator CIITA and found frequent aberrations consisting of structural genomic rearrangements, missense, nonsense, and frame-shift mutations (53% of primary tumor biopsies and all cell lines). We also detected intron 1 mutations in 47% of the cases, and detailed sequence analysis strongly suggests AID-mediated aberrant somatic hypermutation as the mutational mechanism. Furthermore, we demonstrate that genomic lesions in CIITA result in decreased protein expression and reduction of MHC class II surface expression, creating an immune privilege phenotype in PMBCL. In summary, we establish CIITA alterations as a common mechanism of immune escape through reduction of MHC class II expression in PMBCL, with potential implications for future treatments targeting microenvironment-related biology.
[Show abstract][Hide abstract] ABSTRACT: Bortezomib is active in mantle cell lymphoma (MCL), with approval in upfront and relapsed settings. Given inevitable recurrence following induction chemoimmunotherapy, maintenance approaches are a rational strategy to improve clinical outcomes. We conducted a phase II study to evaluate the safety and efficacy of six cycles of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone) plus bortezomib (1·3 mg/m(2) days 1 and 4 of 21 d cycles) followed by bortezomib maintenance (1·3 mg/m(2) days 1, 4, 8, and 11 every 3 months for 2 years). Sixty-five eligible patients were enrolled. The treatment was well tolerated and toxicities were mainly haematological. The rate of grade ≥3 peripheral neuropathy was low (5%). With a median follow-up of 6·8 years, 2-year progression-free survival (PFS) was 62%, and 2-year overall survival (OS) was 85%. At 5 years, PFS was 28% and OS was 66%. MCL International Prognostic Index scores were significantly associated with 2-year PFS, but did not predict long-term (≥5-year) PFS. Baseline Ki-67 index was significantly associated with survival. Combination R-CHOP with bortezomib followed by maintenance bortezomib appears to improve outcomes compared historically with R-CHOP alone, with prolonged remissions in a subset of patients. These results suggest that inclusion of bortezomib with induction chemotherapy and/or maintenance is promising in MCL and warrants further exploration.
British Journal of Haematology 10/2015; DOI:10.1111/bjh.13818 · 4.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) relies on chronic active B-cell receptor (BCR) signaling. BCR pathway inhibitors induce remissions in a subset of ABC DLBCL patients. BCR microclusters on the surface of ABC cells resemble those generated following antigen engagement of normal B cells. We speculated that binding of lymphoma BCRs to self-antigens initiates and maintains chronic active BCR signaling in ABC DLBCL. To assess whether antigenic engagement of the BCR is required for the ongoing survival of ABC cells, we developed isogenic ABC cells that differed solely with respect to the IgH V region of their BCRs. In competitive assays with wild-type cells, substitution of a heterologous V region impaired the survival of three ABC lines. The viability of one VH4-34(+) ABC line and the ability of its BCR to bind to its own cell surface depended on V region residues that mediate the intrinsic autoreactivity of VH4-34 to self-glycoproteins. The BCR of another ABC line reacted with self-antigens in apoptotic debris, and the survival of a third ABC line was sustained by reactivity of its BCR to an idiotypic epitope in its own V region. Hence, a diverse set of self-antigens is responsible for maintaining the malignant survival of ABC DLBCL cells. IgH V regions used by the BCRs of ABC DLBCL biopsy samples varied in their ability to sustain survival of these ABC lines, suggesting a screening procedure to identify patients who might benefit from BCR pathway inhibition.
Proceedings of the National Academy of Sciences 10/2015; DOI:10.1073/pnas.1514944112 · 9.67 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mediastinal involvement is considered essential for the diagnosis of primary mediastinal large B-cell lymphoma (PMBL). However, we have observed cases of diffuse large B-cell lymphoma (DLBCL) with features of PMBL but without detectable mediastinal involvement. The goal was to assess our previously established gene expression profiling (GEP) signature for PMBL in classifying these cases. In a large series of DLBCL cases, we identified 24 cases with a GEP signature of PMBL, including 9 cases with a submission diagnosis of DLBCL consistent with PMBL (G-PMBL-P) and 15 cases with a submission diagnosis of DLBCL. The pathology reviewers agreed with the diagnosis in the 9 G-PMBL-P cases. Among the other 15 DLBCL cases, 11 were considered to be PMBL or DLBCL consistent with PMBL, 3 were considered to be DLBCL, and 1 case was a gray-zone lymphoma with features intermediate between DLBCL and classical Hodgkin lymphoma. All 9 G-PMBL-P and 9 of the 15 DLBCL cases (G-PMBL-M) had demonstrated mediastinal involvement at presentation. Interestingly, 6 of the 15 DLBCL cases (G-PMBL-NM) had no clinical or radiologic evidence of mediastinal involvement. The 3 subgroups of PMBL had otherwise similar clinical characteristics, and there were no significant differences in overall survival. Genetic alterations of CIITA and PDL1/2 were detected in 26% and 40% of cases, respectively, including 1 G-PMBL-NM case with gain of PDL1/2. In conclusion, PMBL can present as a nonmediastinal tumor without evidence of mediastinal involvement, and GEP offers a more precise diagnosis of PMBL.
The American journal of surgical pathology 05/2015; 39(10). DOI:10.1097/PAS.0000000000000473 · 5.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Better treatments are needed for patients with diffuse large B-cell lymphoma (DLBCL) at high risk of failing standard therapy. Avoiding apoptosis is a hallmark of cancer, and in DLBCL the redundantly functioning anti-apoptotic proteins BCL2 and MCL1 are frequently expressed. Here, we explore drugs that cause loss of MCL1, particularly the potent new cyclin-dependent kinase inhibitor dinaciclib, which knocks down MCL1 by inhibiting CDK9. Dinaciclib induces apoptosis in DLBCL cells but is completely overcome by increased activity of BCL2. We find clinical samples have frequent co-expression of MCL1 and BCL2, suggesting therapeutic strategies targeting only one will lead to treatment failures due to activity of the other. The BH3 mimetic ABT-199 potently and specifically targets BCL2. Single-agent ABT-199 had modest anti-tumor activity against most DLBCL lines and resulted in compensatory up-regulation of MCL1 expression. ABT-199 synergized strongly, however, when combined with dinaciclib and with other drugs affecting MCL1, including standard DLBCL chemotherapy drugs. We show potent anti-tumor activities of these combinations in xenografts and in a genetically accurate murine model of MYC-BCL2 double-hit lymphoma. In sum, we reveal a rational treatment paradigm to strip DLBCL of its protection from apoptosis and improve outcomes for high-risk patients.Leukemia accepted article preview online, 17 April 2015. doi:10.1038/leu.2015.99.
Leukemia: official journal of the Leukemia Society of America, Leukemia Research Fund, U.K 04/2015; 29(8). DOI:10.1038/leu.2015.99 · 10.43 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Effective treatment of diffuse large B cell lymphoma (DLBCL) is plagued by heterogeneous responses to standard therapy, and molecular mechanisms underlying unfavorable outcomes in lymphoma patients remain elusive. Here, we profiled 148 genomes with 91 matching transcriptomes in an R-CHOP-treated DLBCL cohort to uncover molecular subgroups linked to treatment failure. Systematic integration of high-resolution genotyping arrays and RNA-seq data revealed novel deletions in RCOR1 to be associated with unfavorable progression free survival (P = 0.001). Integration of expression data from the clinical samples with data from RCOR1 knockdowns in the lymphoma cell lines KM-H2 and Raji yielded an RCOR1 loss-associated gene signature comprising of 233 genes. This signature identified a subgroup of patients with unfavorable overall survival (OS) (P = 0.023). The prognostic significance of the 233-gene signature for OS was reproduced in an independent cohort comprising 195 R-CHOP treated patients (P = 0.039). Additionally, we discovered that within the IPI low risk group, the gene signature provides additional prognostic value that was independent of the cell-of-origin phenotype. Taken together, we present a novel and reproducible molecular subgroup of DLBCL, impacting risk-stratification of R-CHOP treated DLBCL patients and revealing a possible new avenue for therapeutic intervention strategies.
[Show abstract][Hide abstract] ABSTRACT: Patients with aggressive, BCL2 protein-positive (+) diffuse large B-cell lymphoma (DLBCL) often experience rapid disease progression that is refractory to standard therapy. However, there is potential for false-negative staining of BCL2 using the standard monoclonal mouse 124 antibody that hinders the identification of these high-risk DLBCL patients. Herein, we compare two alternative rabbit monoclonal antibodies (E17 and SP66) to the 124 clone in staining for BCL2 in formalin-fixed, paraffin-embedded DLBCL tissues. Overall, in two independent DLBCL cohorts E17 and SP66 detected BCL2 expression more frequently than 124. In the context of MYC expression, cases identified as BCL2 (+) with SP66 demonstrated the strongest correlation with worse OS. The 124 clone failed to detect BCL2 expression in the majority of translocation (+), amplification (+), and activated B-cell DLBCL cases in which high levels of BCL2 protein are expected. Using dual in-situ hybridization (Dual ISH) as a new tool to detect BCL2 translocation and amplification, we observed similar results as previously reported for fluorescence ISH for translocation but a higher amplification frequency, indicating that BCL2 amplification may be under-reported in DLBCL. Among the discrepant cases, phosphorylation of BCL2 at T69 and/or S70 was more common than in the concordant cases and may contribute to the 124 false-negatives, in addition to previously associated mutations within the epitope region. The accurate detection of BCL2 expression is important in the prognosis and treatment of DLBCL particularly with new anti-BCL2 therapies.
Human pathology 10/2014; 45(10). DOI:10.1016/j.humpath.2014.06.005 · 2.77 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Germinal center (GC) B cell-like diffuse large B cell lymphoma (GCB-DLBCL) is a common malignancy yet the signaling pathways deregulated and the factors leading to its systemic dissemination are poorly defined1,2. Work in mice showed that sphingosine-1-phosphate receptor-2 (S1PR2), a Gα12 and Gα13 coupled receptor, promotes growth regulation and local confinement of GC B cells3,4. Recent GCB-DLBCL deep sequencing studies have revealed mutations in a large number of genes in this cancer, including in GNA13 (encoding Gα13) and S1PR25-7. Here we show using in vitro and in vivo assays that GCB-DLBCL associated mutations occurring in S1PR2 frequently disrupt the receptor's Akt and migration inhibitory functions. Gα13-deficient mouse GC B cells and human GCB-DLBCL cells were unable to suppress pAkt and migration in response to S1P, and Gα13-deficient mice developed GC B cell-derived lymphoma. GC B cells, unlike most lymphocytes, are tightly confined in lymphoid organs and do not recirculate. Remarkably, deficiency in Gα13, but not S1PR2, led to GC B cell dissemination into lymph and blood. GCB-DLBCL cell lines frequently carried mutations in the Gα13 effector ARHGEF1, and Arhgef1-deficiency also led to GC B cell dissemination. The incomplete phenocopy of Gα13- and S1PR2-deficiency led us to discover that P2RY8, an orphan receptor that is mutated in GCB-DLBCL and another GC B cell-derived malignancy, Burkitt lymphoma (BL), also represses GC B cell growth and promotes confinement via Gα13. These findings identify a Gα13-dependent pathway that exerts dual actions in suppressing growth and blocking dissemination of GC B cells that is frequently disrupted in GC B cell-derived lymphoma.
[Show abstract][Hide abstract] ABSTRACT: Detection of B cell clonality is useful for assisting in the diagnosis of B cell lymphomas. Clonality assessment can be accomplished through evaluation of KAPPA and LAMBDA light chain expression. Currently, only slide based methods are available for the majority of patient biopsies and do not detect light chain protein or mRNA in many B-cell lymphomas. Herein we evaluated a new method, known as colorimetric in situ hybridization (CISH), with improved sensitivity and multiplexing capacity, for its usefulness in clonality detection in mature B cell malignancies.
The KAPPA and LAMBDA ISH was performed on a Ventana Benchmark XT utilizing two color chromogenetic detection. The probes comprised 2 haptenated riboprobes each approximately 500 base pairs long directed against the conserved regions of either KAPPA or LAMBDA mRNA. The dual colors consisted of silver deposition (black) for KAPPA light chain and a novel (pink) chromogen for LAMBDA light chain. Following optimization, CISH allowed visualization of mRNA in benign B cells in reactive tissues including germinal center, mantle zone, and post-germinal center cells. We then identified 79 cases of B cell lymphoma with formalin-fixed paraffin-embedded (FFPE) biopsies including: follicular (36 cases), mantle cell (6 cases), marginal zone (12 cases), lymphoplasmacytic (6 cases), small lymphocytic (4 cases), and diffuse large B cell (15 cases), which were selected on the basis of either prior flow cytometry or immunohistochemistry (IHC) results to serve as the predicate, "gold standard," comparator.
39/79 (49.4%) cases were classified as KAPPA and 29/79 (36.7%) as LAMBDA light chain restricted; while 9/79 (11.3%) cases were classified as indeterminate. Of the 70 cases with KAPPA or LAMBDA light chain restricted CISH, 69/70 (98.6%) were concordant with the reference method, while 1/70 (1.4%) was discordant.
Optimized CISH detected lower levels of mRNA than can be visualized with current slide based methods, making clonality assessment in FFPE biopsies possible for mature B cell neoplasms. In this preliminary study, CISH was highly accurate compared to flow cytometry or IHC. CISH offers the possibility of wider applicability of light chain ISH and is likely to become a useful diagnostic tool.
The virtual slide(s) for this article can be found here:
[Show abstract][Hide abstract] ABSTRACT: Lymphoma cells are subject to higher levels of oxidative stress as compared to their normal counterparts and may be vulnerable to manipulations of the cellular redox balance. We therefore designed a phase II study of imexon (Amplimexon/NSC-714597), a pro-oxidant molecule, in patients with relapsed / refractory B-cell non-Hodgkin lymphomas (NHL). Imexon was administered at 1000 mg/m2 intravenously daily for 5 days in 21-day cycles. Gene expression analysis performed on pre-treatment tumor specimens included 13 transcripts used to generate a redox signature score, previously demonstrated to correlate with lymphoma prognosis. Twenty-two patients were enrolled having follicular (n=9), diffuse large B-cell (DLBCL) (n=5), mantle cell (n=3), transformed follicular (n=2), small lymphocytic (n=2) and Burkitt (n=1) lymphoma. The most common grade 3/4 adverse events were anemia (14%) and neutropenia (9%). The overall response rate was 30%: including responses in follicular lymphoma (4/9) and DLBCL (2/5). Gene expression analyses revealed CD68 and the redox related genes, GPX1 and SOD2, as well as a higher redox score to correlate with clinical responses. To our knowledge, this is the first demonstration of clinical activity with a pro-oxidant molecule in lymphoma. Pre-treatment markers of oxidative stress may identify patients likely to respond to this therapeutic approach. This study was registered at ClinicalTrials.gov as #NCT01314014.