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Burkitt lymphoma (BL) is an aggressive lymphoma type that is currently treated by intensive chemoimmunotherapy. Despite the favorable clinical outcome for most patients with BL, chemotherapy-related toxicity and disease relapse remain major clinical challenges, emphasizing the need for innovative therapies. Using genome-scale CRISPR-Cas9 screens, we identified B-cell receptor (BCR) signaling, specific transcriptional regulators, and one-carbon metabolism as vulnerabilities in BL. We focused on serine hydroxymethyltransferase 2 (SHMT2), a key enzyme in one-carbon metabolism. Inhibition of SHMT2 by either knockdown or pharmacological compounds induced anti-BL effects in vitro and in vivo. Mechanistically, SHMT2 inhibition led to a significant reduction of intracellular glycine and formate levels, which inhibited the mTOR pathway and thereby triggered autophagic degradation of the oncogenic transcription factor TCF3. Consequently, this led to a collapse of tonic BCR signaling, which is controlled by TCF3 and is essential for BL cell survival. In terms of clinical translation, we also identified drugs such as methotrexate that synergized with SHMT inhibitors. Overall, our study has uncovered the dependency landscape in BL, identified and validated SHMT2 as a drug target, and revealed a mechanistic link between SHMT2 and the transcriptional master regulator TCF3, opening up new perspectives for innovative therapies.

Myocardial infarction is a frequent cause of out-of-hospital cardiac arrest. However, the benefits of early coronary angiography and revascularization in resuscitated patients without electrocardiographic evidence of ST-segment elevation are unclear.In this multicenter trial, we randomly assigned 554 patients with successfully resuscitated out-of-hospital cardiac arrest of possible coronary origin to undergo either immediate coronary angiography (immediate-angiography group) or initial intensive care assessment with delayed or selective angiography (delayed-angiography group). All the patients had no evidence of ST-segment elevation on postresuscitation electrocardiography. The primary end point was death from any cause at 30 days. Secondary end points included a composite of death from any cause or severe neurologic deficit at 30 days.A total of 530 of 554 patients (95.7%) were included in the primary analysis. At 30 days, 143 of 265 patients (54.0%) in the immediate-angiography group and 122 of 265 patients (46.0%) in the delayed-angiography group had died (hazard ratio, 1.28; 95% confidence interval [CI], 1.00 to 1.63; P = 0.06). The composite of death or severe neurologic deficit occurred more frequently in the immediate-angiography group (in 164 of 255 patients [64.3%]) than in the delayed-angiography group (in 138 of 248 patients [55.6%]), for a relative risk of 1.16 (95% CI, 1.00 to 1.34). Values for peak troponin release and for the incidence of moderate or severe bleeding, stroke, and renal-replacement therapy were similar in the two groups.Among patients with resuscitated out-of-hospital cardiac arrest without ST-segment elevation, a strategy of performing immediate angiography provided no benefit over a delayed or selective strategy with respect to the 30-day risk of death from any cause. (Funded by the German Center for Cardiovascular Research; TOMAHAWK ClinicalTrials.gov number, NCT02750462.).

Genomic analyses of diffuse large B cell lymphoma (DLBCL) are revealing the genetic and phenotypic heterogeneity of these aggressive lymphomas. In part, this heterogeneity reflects the existence of distinct genetic subtypes that acquire characteristic constellations of somatic genetic alterations to converge on the DLBCL phenotype. In parallel, functional genomic screens and proteomic analyses have identified multiprotein assemblies that coordinate oncogenic survival signaling in DLBCL. In this review, we merge these recent insights into a unified conceptual framework with implications for the design of precision medicine trials in DLBCL.

Background: A significant proportion of patients presenting with acute myocardial infarction (MI) has no coronary obstruction at coronary angiography and no other obvious non-coronary pathophysiology causing MI. These patients are classified as MI with non-obstructive coronary arteries (MINOCA). Data on incidence and predictors of MINOCA are still limited. Methods: This study enrolled patients presenting symptoms suggestive of MI and undergoing a comprehensive cardiac work-up including an early invasive strategy. Patients with non-obstructive coronary arteries and without other obvious reasons for MI were scheduled for further work-up including magnetic resonance or intraluminal imaging. MINOCA was diagnosed according to the current European Society of Cardiology guidelines. Results: From the 1532 patients enrolled, 730 had available coronary imaging and 546 were diagnosed with MI. No significant coronary obstructions were found in 117 patients with MI. After the exclusion of 6 patients with acute myocarditis or takotsubo-syndrome as well as 88 with type II MI, 23 patients were diagnosed with MINOCA (4% of all MIs). Among these 23 patients, the most common etiology of MINOCA was thromboembolic events followed by coronary spasm. Female sex, the absence of hypercholesterolemia, and a normal left-ventricular ejection fraction were independently predictive for MINOCA compared to patients with other causes of MI. Conclusion: More than 20% of patients presenting with acute MI showed no significant coronary obstruction. About 4% of these patients were diagnosed with MINOCA. Female sex, a lower cardiovascular risk profile, and normal left-ventricular function were predictive for MINOCA.

The development of precision medicine approaches for diffuse large B cell lymphoma (DLBCL) is confounded by its pronounced genetic, phenotypic, and clinical heterogeneity. Recent multiplatform genomic studies revealed the existence of genetic subtypes of DLBCL using clustering methodologies. Here, we describe an algorithm that determines the probability that a patient's lymphoma belongs to one of seven genetic subtypes based on its genetic features. This classification reveals genetic similarities between these DLBCL subtypes and various indolent and extranodal lymphoma types, suggesting a shared pathogenesis. These genetic subtypes also have distinct gene expression profiles, immune microenvironments, and outcomes following immunochemotherapy. Functional analysis of genetic subtype models highlights distinct vulnerabilities to targeted therapy, supporting the use of this classification in precision medicine trials.

Although generally curable with intensive chemotherapy in resource-rich settings, Burkitt lymphoma (BL) remains a deadly disease in older patients and in sub-Saharan Africa. Epstein-Barr virus (EBV) positivity is a feature in more than 90% of cases in malaria-endemic regions, and up to 30% elsewhere. However, the molecular features of BL have not been comprehensively evaluated when taking into account tumor EBV status or geographic origin. Through an integrative analysis of whole-genome and transcriptome data, we show a striking genome-wide increase in aberrant somatic hypermutation in EBV-positive tumors, supporting a link between EBV and activation-induced cytidine deaminase (AICDA) activity. In addition to identifying novel candidate BL genes such as SIN3A, USP7, and CHD8, we demonstrate that EBV-positive tumors had significantly fewer driver mutations, especially among genes with roles in apoptosis. We also found immunoglobulin variable region genes that were disproportionally used to encode clonal B-cell receptors (BCRs) in the tumors. These include IGHV4-34, known to produce autoreactive antibodies, and IGKV3-20, a feature described in other B-cell malignancies but not yet in BL. Our results suggest that tumor EBV status defines a specific BL phenotype irrespective of geographic origin, with particular molecular properties and distinct pathogenic mechanisms. The novel mutation patterns identified here imply rational use of DNA-damaging chemotherapy in some patients with BL and targeted agents such as the CDK4/6 inhibitor palbociclib in others, whereas the importance of BCR signaling in BL strengthens the potential benefit of inhibitors for PI3K, Syk, and Src family kinases among these patients.

Patients experiencing out-of-hospital cardiac arrest (OHCA) without ST-segment elevation are a heterogenic group with a variety of underlying causes. Up to one-third of patients display a significant coronary lesion compatible with myocardial infarction as OHCA trigger. There are no randomized data on patient selection and timing of invasive coronary angiography after admission. METHODS AND RESULTS: The TOMAHAWK trial randomly assigns 558 patients with return of spontaneous circulation after OHCA with no obvious extracardiac origin of cardiac arrest and no ST-segment elevation/left bundle-branch block on postresuscitation electrocardiogram to either immediate coronary angiography or initial intensive care assessment with delayed/selective angiography in a 1:1 ratio. The primary end point is 30-day all-cause mortality. Secondary analyses will be performed with respect to initial rhythm, electrocardiographic patterns, myocardial infarction as underlying cause, neurological outcome, as well as clinical and laboratory markers. Clinical follow-up will be performed at 6 and 12 months. Safety end points include bleeding and stroke. CONCLUSION: The TOMAHAWK trial will address the unresolved issue of timing and general indication of angiography after OHCA without ST-segment elevation.

BACKGROUND: Diffuse large B-cell lymphomas (DLBCLs) are phenotypically and genetically heterogeneous. Gene-expression profiling has identified subgroups of DLBCL (activated B-cell-like [ABC], germinal-center B-cell-like [GCB], and unclassified) according to cell of origin that are associated with a differential response to chemotherapy and targeted agents. We sought to extend these findings by identifying genetic subtypes of DLBCL based on shared genomic abnormalities and to uncover therapeutic vulnerabilities based on tumor genetics. METHODS: We studied 574 DLBCL biopsy samples using exome and transcriptome sequencing, array-based DNA copy-number analysis, and targeted amplicon resequencing of 372 genes to identify genes with recurrent aberrations. We developed and implemented an algorithm to discover genetic subtypes based on the co-occurrence of genetic alterations. RESULTS: We identified four prominent genetic subtypes in DLBCL, termed MCD (based on the co-occurrence of MYD88L265P and CD79B mutations), BN2 (based on BCL6 fusions and NOTCH2 mutations), N1 (based on NOTCH1 mutations), and EZB (based on EZH2 mutations and BCL2 translocations). Genetic aberrations in multiple genes distinguished each genetic subtype from other DLBCLs. These subtypes differed phenotypically, as judged by differences in gene-expression signatures and responses to immunochemotherapy, with favorable survival in the BN2 and EZB subtypes and inferior outcomes in the MCD and N1 subtypes. Analysis of genetic pathways suggested that MCD and BN2 DLBCLs rely on "chronic active" B-cell receptor signaling that is amenable to therapeutic inhibition. CONCLUSIONS: We uncovered genetic subtypes of DLBCL with distinct genotypic, epigenetic, and clinical characteristics, providing a potential nosology for precision-medicine strategies in DLBCL. (Funded by the Intramural Research Program of the National Institutes of Health and others.).

B cell receptor (BCR) signalling has emerged as a therapeutic target in B cell lymphomas, but inhibiting this pathway in diffuse large B cell lymphoma (DLBCL) has benefited only a subset of patients1. Gene expression profiling identified two major subtypes of DLBCL, known as germinal centre B cell-like and activated B cell-like (ABC)2,3, that show poor outcomes after immunochemotherapy in ABC. Autoantigens drive BCR-dependent activation of NF-κB in ABC DLBCL through a kinase signalling cascade of SYK, BTK and PKCβ to promote the assembly of the CARD11-BCL10-MALT1 adaptor complex, which recruits and activates IκB kinase4-6. Genome sequencing revealed gain-of-function mutations that target the CD79A and CD79B BCR subunits and the Toll-like receptor signalling adaptor MYD885,7, with MYD88(L265P) being the most prevalent isoform. In a clinical trial, the BTK inhibitor ibrutinib produced responses in 37% of cases of ABC1. The most striking response rate (80%) was observed in tumours with both CD79B and MYD88(L265P) mutations, but how these mutations cooperate to promote dependence on BCR signalling remains unclear. Here we used genome-wide CRISPR-Cas9 screening and functional proteomics to determine the molecular basis of exceptional clinical responses to ibrutinib. We discovered a new mode of oncogenic BCR signalling in ibrutinib-responsive cell lines and biopsies, coordinated by a multiprotein supercomplex formed by MYD88, TLR9 and the BCR (hereafter termed the My-T-BCR supercomplex). The My-T-BCR supercomplex co-localizes with mTOR on endolysosomes, where it drives pro-survival NF-κB and mTOR signalling. Inhibitors of BCR and mTOR signalling cooperatively decreased the formation and function of the My-T-BCR supercomplex, providing mechanistic insight into their synergistic toxicity for My-T-BCR+ DLBCL cells. My-T-BCR supercomplexes characterized ibrutinib-responsive malignancies and distinguished ibrutinib responders from non-responders. Our data provide a framework for the rational design of oncogenic signalling inhibitors in molecularly defined subsets of DLBCL.

The two major subtypes of diffuse large B cell lymphoma (DLBCL)—activated B cell–like (ABC) and germinal center B cell–like (GCB)—arise by distinct mechanisms, with ABC selectively acquiring mutations that target the B cell receptor (BCR), fostering chronic active BCR signaling(1). The ABC subtype has a ∼40% cure rate with currently available therapies, which is worse than the rate for GCB DLBCL, and highlights the need for ABC subtype-specific treatment strategies(2). We hypothesized that ABC, but not GCB, DLBCL tumors would respond to ibrutinib, an inhibitor of BCR signaling. In a phase 1/2 clinical trial that involved 80 subjects with relapsed or refractory DLBCL, ibrutinib produced complete or partial responses in 37% (14/38) of those with ABC DLBCL, but in only 5% (1/20) of subjects with GCB DLBCL (P = 0.0106). ABC tumors with BCR mutations responded to ibrutinib frequently (5/9; 55.5%), especially those with concomitant myeloid differentiation primary response 88 (MYD88) mutations (4/5; 80%), a result that is consistent with in vitro cooperation between the BCR and MYD88 pathways. However, the highest number of responses occurred in ABC tumors that lacked BCR mutations (9/29; 31%), suggesting that oncogenic BCR signaling in ABC does not require BCR mutations and might be initiated by non-genetic mechanisms. These results support the selective development of ibrutinib for the treatment of ABC DLBCL.

Bone marrow monoclonal small B-cell infiltration (MSBC) associated with monoclonal B lymphocytosis (MBL), is present at a higher frequency in patients with diffuse large B-cell lymphoma (DLBCL). We have prospectively collected blood and bone marrow (BM) samples in patients with primary DLBCL at

Adult T cell leukemia/lymphoma (ATLL) is an aggressive malignancy caused by human T cell lymphotropic virus type-I (HTLV-I) without curative treatment at present. To illuminate the pathogenesis of ATLL we performed whole transcriptome sequencing of purified ATLL patient samples and discovered recurrent somatic mutations in CCR4, encoding CC chemokine receptor 4. CCR4 mutations were detected in 14/53 ATLL samples (26%) and consisted exclusively of nonsense or frameshift mutations that truncated the coding region at C329, Q330, or Y331 in the carboxy terminus. Functionally, the CCR4-Q330 nonsense isoform was gain-of-function because it increased cell migration toward the CCR4 ligands CCL17 and CCL22, in part by impairing receptor internalization. This mutant enhanced PI(3) kinase/AKT activation after receptor engagement by CCL22 in ATLL cells and conferred a growth advantage in long-term in vitro cultures. These findings implicate somatic gain-of-function CCR4 mutations in the pathogenesis of ATLL and suggest that inhibition of CCR4 signaling might have therapeutic potential in this refractory malignancy.

ObjectiveThis study sought to evaluate the diagnostic performance of the 1-hour troponin algorithm for diagnosis of myocardial infarction (MI) without persistent ST-segment elevations (non-ST-segment MI (NSTEMI)) in a cohort with a high prevalence of MI. This algorithm recommend by current guidelines was previously developed in cohorts with a prevalence of MI of less than 20%.DesignProspective cohort study from November 2015 until December 2016.SettingDedicated chest pain unit of a single referral centre.ParticipantsConsecutive patients with suspected MI were screened. Patients with subacute symptoms lasting more than 24 hours, new ST-segment elevations at presentation, or an already diagnosed or ruled-out acute MI were excluded. All enrolled patients (n=1317) underwent a full clinical assessment and measurements of high-sensitivity troponin, and were scheduled for an early invasive strategy if clinically indicated.Main outcome measuresFinal diagnosis of MI according to the Fourth Universal Definition of MI.ResultsThe prevalence of NSTEMI in the present cohort was 36.9%. The sensitivity for rule-out of MI was 99.8%. The specificity for rule-in of MI was found to be 94.3%. However, in 35.7% of patients neither rule-in nor rule-out was possible. In 51.4% of patients diagnosed with MI, a primary non-coronary reason for MI was found (type 2 MI). Different receiver operating characteristic-curve derived cut-offs for troponin and its dynamics did not provide a sufficient differentiation between type 1 and 2 MI for clinical decision making (negative predictive value for rule-out of type 1 MI ConclusionsThe 1-hour diagnosis algorithm for patients with suspected NSTEMI can accurately diagnose acute MI in high-risk cohorts. However, discrimination between patients needing an early invasive strategy or not is limited.Trial registration numberDRKS00009713.

Germline mutations in CARD11 that result in constitutive NF-κB activation and selective B cell expansion underlie congenital B cell lymphocytosis., Nuclear factor-κB (NF-κB) controls genes involved in normal lymphocyte functions, but constitutive NF-κB activation is often associated with B cell malignancy. Using high-throughput whole transcriptome sequencing, we investigated a unique family with hereditary polyclonal B cell lymphocytosis. We found a novel germline heterozygous missense mutation (E127G) in affected patients in the gene encoding CARD11, a scaffolding protein required for antigen receptor (AgR)–induced NF-κB activation in both B and T lymphocytes. We subsequently identified a second germline mutation (G116S) in an unrelated, phenotypically similar patient, confirming mutations in CARD11 drive disease. Like somatic, gain-of-function CARD11 mutations described in B cell lymphoma, these germline CARD11 mutants spontaneously aggregate and drive constitutive NF-κB activation. However, these CARD11 mutants rendered patient T cells less responsive to AgR-induced activation. By reexamining this rare genetic disorder first reported four decades ago, our findings provide new insight into why activating CARD11 mutations may induce B cell expansion and preferentially predispose to B cell malignancy without dramatically perturbing T cell homeostasis.

The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) remains the least curable form of this malignancy despite recent advances in therapy1. Constitutive nuclear factor (NF)-κB and JAK kinase signalling promotes malignant cell survival in these lymphomas, but the genetic basis for this signalling is incompletely understood. Here we describe the dependence of ABC DLBCLs on MYD88, an adaptor protein that mediates toll and interleukin (IL)-1 receptor signalling2,3, and the discovery of highly recurrent oncogenic mutations affecting MYD88 in ABC DLBCL tumours. RNA interference screening revealed that MYD88 and the associated kinases IRAK1 and IRAK4 are essential for ABC DLBCL survival. High-throughput RNA resequencing uncovered MYD88 mutations in ABC DLBCL lines. Notably, 29% of ABC DLBCL tumours harboured the same amino acid substitution, L265P, in the MYD88 Toll/IL-1 receptor (TIR) domain at an evolutionarily invariant residue in its hydrophobic core. This mutation was rare or absent in other DLBCL subtypes and Burkitt’s lymphoma, but was observed in 9% of mucosa-associated lymphoid tissue lymphomas. At a lower frequency, additional mutations were observed in the MYD88 TIR domain, occurring in both the ABC and germinal centre B-cell-like (GCB) DLBCL subtypes. Survival of ABC DLBCL cells bearing the L265P mutation was sustained by the mutant but not the wild-type MYD88 isoform, demonstrating that L265P is a gain-of-function driver mutation. The L265P mutant promoted cell survival by spontaneously assembling a protein complex containing IRAK1 and IRAK4, leading to IRAK4 kinase activity, IRAK1 phosphorylation, NF-κB signalling, JAK kinase activation of STAT3, and secretion of IL-6, IL-10 and interferon-β. Hence, theMYD88 signalling pathway is integral to the pathogenesis of ABC DLBCL, supporting the development of inhibitors of IRAK4 kinase and other components of this pathway for the treatment of tumours bearing oncogenic MYD88 mutations.

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.

Chronic active B cell receptor (BCR) signaling, a hallmark of the activated B cell-like (ABC) subtype of diffuse large B cell lymphoma (DLBCL), engages the CARD11-MALT1-BCL10 (CBM) adapter complex to activate IκB kinase (IKK) and the classical NF-κB pathway. Here we show that the CBM complex includes the E3 ubiquitin ligases cIAP1 and cIAP2, which are essential mediators of BCR-dependent NF-κB activity in ABC DLBCL. cIAP1/2 attach K63-linked polyubiquitin chains on themselves and on BCL10, resulting in the recruitment of IKK and the linear ubiquitin chain ligase LUBAC, which is essential for IKK activation. SMAC mimetics target cIAP1/2 for destruction, and consequently suppress NF-κB and selectively kill BCR-dependent ABC DLBCL lines, supporting their clinical evaluation in patients with ABC DLBCL.

Chromosomal breakpoints affecting immunoglobulin (IG) loci are recurrent in many subtypes of B-cell lymphomas. However, despite the predominant B-cell origin of the Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (cHL), the presence of chromosomal translocations in IG loci has not yet been systematically explored. Therefore, we have investigated a series of cHL for chromosomal breakpoints in the IGH (n = 230), IGL (n = 139), and IGK (n = 138) loci by interphase cytogenetics. Breakpoints in the IGH, IGL, or IGK locus were observed in the HRS cells of 26 of 149 (17%), 2 of 70, and 1 of 77 evaluable cHLs, respectively. The IG partners could be identified in eight cHLs and involved chromosomal bands 2p16 (REL), 3q27 (BCL6, two cases), 8q24.1 (MYC), 14q24.3, 16p13.1, 17q12, and 19q13.2 (BCL3/RELB). In 65 of 85 (76%) cHLs evaluable for an IGH triple-color probe, the HRS cells showed evidence for a (partial) deletion of the IGH constant region, suggesting the presence of class switch recombination (CSR). Furthermore, analyses with this probe in cases with IGH breakpoints indicated that at least part of them seem to be derived from CSR defects. Our results show that chromosomal breakpoints affecting the IG loci are recurrent in cHL. (Cancer Res 2006; 66(21): 10332-8)

Hodgkin's and Reed/Sternberg (HRS) cells, the tumour cells in classical Hodgkin's lymphoma (HL), represent transformed B cells in nearly all cases. The detection of destructive somatic mutations in the rearranged immunoglobulin (Ig) genes of HRS cells in classical HL indicated that they originate from preapoptotic germinal centre (GC) B cells that lost the capacity to express a high-affinity B-cell receptor (BCR). Several aberrantly activated signalling pathways and transcription factors have been identified that contribute to the rescue of HRS cells from apoptosis. Among the deregulated signalling pathways, activation of multiple receptor tyrosine kinases in HRS cells appears to be a specific feature of HL. In about 40% of cases of classical HL the HRS cells are infected by Epstein-Barr virus (EBV), indicating an important role of EBV in HL pathogenesis. Interestingly, nearly all cases of HL with destructive Ig gene mutations eliminating BCR expression (e.g. nonsense mutations) are EBV-positive, suggesting that EBV-encoded genes have a particular function to prevent apoptosis of HRS-cell precursors that acquired such crippling mutations. This idea is further supported by the recent demonstration that isolated human GC B cells harbouring crippled Ig genes can be rescued by EBV from cell death, giving rise to lymphoblastoid cell lines. The molecular analysis of composite Hodgkin's and non-Hodgkin's lymphomas indicated that many cases develop from a common GC B-cell precursor in a multistep transformation process with both shared and distinct oncogenic events.

In Hodgkin's lymphoma (HL), the B cell origin of the tumour cells, the Hodgkin and Reed-Sternberg (HRS) cells, has been disclosed by molecular single cell analysis about 10 yr ago. This finding formed the basis for various studies aimed to better understand the pathogenesis of this peculiar malignancy and the pathophysiology of the HRS cells. Work of our groups in this regard was focussed recently on two main topics, namely the study of differential gene expression in HRS cells and the pathogenesis of composite lymphomas. Composite lymphomas are combinations of HL and B cell non-Hodgkin lymphomas, that turned out to be often clonally related. By molecular analysis of several composite lymphomas for potential transforming events, we identified examples of both shared as well as distinct transforming events. Comparing gene expression profiles of HL-derived cell lines with the corresponding profiles from other B cell lymphomas and normal B cell subsets revealed a global down-regulation of the B cell-specific gene expression signature in HRS cells. Moreover, we identifed aberrant expression and activity of multiple receptor tyrosine kinases in HRS cells of classical and to a lesser extend lymphocyte predominant HL, which appears to be a unique feature of HL, and may offer novel strategies for treatment.

Summary The lymphoma cells of the activated B cell-like (ABC-) subtype of diffuse large B-cell lymphoma (DLBCL) show constitutive activity of the transcription factor, nuclear factor j B( NFjB). We sought to determine whether mutations in the IjBa gene ‐ the predominant inhibitor of NFj B‐ might play a role in the pathogenesis of ABC-DLBCL. All exons of the IjBa gene were directly sequenced from 10 cases of immunohistochemically classified ABC-DLBCL and from six non-ABC-DLBCL cases. Two novel polymorphisms were identified, based on their presence in tumour as well as non-tumour DNA of the respective patients: a duplication near the transcriptional start and a single nucleotide exchange in exon 1. A somatic missense mutation was identified in exon 3, in addition to a wild-type sequence in only one ABC-DLBCL case. Thus, also in this case no clonal biallelic inactivating mutation was present in the IjBa gene. We conclude that mutations in the IjBa gene do not play a dominant role in the pathogenesis of ABC-DLBCL.

Primary CNS lymphoma (PCNSL) harbors mutations that reinforce B cell receptor (BCR) signaling. Ibrutinib, a Bruton's tyrosine kinase (BTK) inhibitor, targets BCR signaling and is particularly active in lymphomas with mutations altering the BCR subunit CD79B and MYD88. We performed a proof-of-concept phase Ib study of ibrutinib monotherapy followed by ibrutinib plus chemotherapy (DA-TEDDi-R). In 18 PCNSL patients, 94% showed tumor reductions with ibrutinib alone, including patients having PCNSL with CD79B and/or MYD88 mutations, and 86% of evaluable patients achieved complete remission with DA-TEDDi-R. Increased aspergillosis was observed with ibrutinib monotherapy and DA-TEDDi-R. Aspergillosis was linked to BTK-dependent fungal immunity in a murine model. PCNSL is highly dependent on BCR signaling, and ibrutinib appears to enhance the efficacy of chemotherapy.

Constitutive activation of NF-κB is a hallmark of the activated B cell–like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL), owing to upstream signals from the B-cell receptor (BCR) and MYD88 pathways. The linear polyubiquitin chain assembly complex (LUBAC) attaches linear polyubiquitin chains to IκB kinase-γ, a necessary event in some pathways that engage NF-κB. Two germline polymorphisms affecting the LUBAC subunit RNF31 are rare among healthy individuals (∼1%) but enriched in ABC DLBCL (7.8%). These polymorphisms alter RNF31 α-helices that mediate binding to the LUBAC subunit RBCK1, thereby increasing RNF31–RBCK1 association, LUBAC enzymatic activity, and NF-κB engagement. In the BCR pathway, LUBAC associates with the CARD11–MALT1–BCL10 adapter complex and is required for ABC DLBCL viability. A stapled RNF31 α-helical peptide based on the ABC DLBCL–associated Q622L polymorphism inhibited RNF31–RBCK1 binding, decreased NF-κB activation, and killed ABC DLBCL cells, credentialing this protein–protein interface as a therapeutic target. Significance: We provide genetic, biochemical, and functional evidence that the LUBAC ubiquitin ligase is a therapeutic target in ABC DLBCL, the DLBCL subtype that is most refractory to current therapy. More generally, our findings highlight the role of rare germline-encoded protein variants in cancer pathogenesis. Cancer Discov; 4(4); 480–93. ©2014 AACR. See related commentary by Grumati and Dikic, p. 394 This article is highlighted in the In This Issue feature, p. 377

Burkitt lymphoma is a germinal center B-cell-derived cancer that was instrumental in the identification of MYC as an important human oncogene more than three decades ago. Recently, new genomics technologies have uncovered several additional oncogenic mechanisms that cooperate with MYC to create this highly aggressive cancer. The transcription factor TCF-3 is central to Burkitt lymphoma pathogenesis. TCF-3 is rendered constitutively active in Burkitt lymphoma by two related mechanisms: (1) somatic mutations that inactivate its negative regulator ID3, and (2) somatic mutations in TCF-3 that block the ability of ID3 to bind and interfere with its activity as a transcription factor. TCF-3 is also a master regulator of normal germinal center B-cell differentiation. Within the germinal center, TCF-3 up-regulates genes that are characteristically expressed in the rapidly dividing centroblasts, the putative cell of origin for Burkitt lymphoma, while repressing genes expressed in the less proliferative centrocytes. TCF-3 promotes antigen-independent (tonic) B-cell-receptor signaling in Burkitt lymphoma by transactivating immunoglobulin heavy- and light-chain genes while repressing PTPN6, which encodes the phosphatase SHP-1, a negative regulator of B-cell-receptor signaling. Tonic B-cell-receptor signaling sustains Burkitt lymphoma survival by engaging the PI3 kinase pathway. In addition, TCF-3 promotes cell-cycle progression by transactivating CCND3, encoding a D-type cyclin that regulates the G1-S phase transition. Additionally, CCND3 accumulates oncogenic mutations that stabilize cyclin D3 protein expression and drive proliferation. These new insights into Burkitt lymphoma pathogenesis suggest new therapeutic strategies, which are sorely needed in developing regions of the world where this cancer is endemic.

Introduction: Burkitt Lymphoma (BL) is an aggressive B-cell lymphoma with a translocation involving MYC and immunoglobulin(Ig) loci. It is most common in children, but also affects adults, and occurs in sporadic, endemic and HIV-associated forms. The Epstein-Barr virus (EBV)-associated endemic subtype is the most common pediatric cancer in equatorial Africa, but also occurs in other parts of the world, for example in the rain forest of Brazil. Intensive chemotherapy is effective, but the associated toxicity requires supportive care that is not readily available in resource-poor regions. Previously published molecular characterization of small numbers of tumors indicated that the mutation profiles of endemic and sporadic cases are similar, but not identical. One goal of the BLGSP is to conduct comprehensive molecular characterization of BL by sequencing DNA and RNA from a large BL cohort - including endemic, sporadic, pediatric and adult cases - in order to define the genetic and phenotypic features that drive these cancers. These data will be analyzed with an intent toward developing new therapeutic strategies that can be deployed worldwide. Methods: The goal is to collect 160 BL cases, of which 50% will be endemic, 38% sporadic (pediatric and adult) and 12% from HIV+ patients. For the discovery phase, each tumor requires case-matching normal DNA as well as treatment, outcome and other clinical information. The optimal source of tumor DNA and RNA is from frozen tissue with at least 50% tumor nuclei, but FFPE immobilization is also accepted. Accrual locations include Africa, Brazil, Europe and the US. The BLGSP has developed extensive standard operating procedures for tissue collection, pathology review and tissue processing to reduce the variation associated with these parameters in the interpretation of the results (see https://ocg.cancer.gov/programs/cgci/projects/burkitt-lymphoma). The project also established procedures that allow sharing of all clinical and sample information through the National Cancer Institute Genomic Data Commons (https://gdc.cancer.gov). Molecular characterization includes whole genome sequencing of tumor and normal DNA (80X and 40X coverage, respectively), RNA-sequencing (RNA-seq) and micro-RNA sequencing. These data will enable the BLGSP to identify chromosomal rearrangements, chromosomal copy number alternations, somatic mutations (single nucleotide, insertions, deletions), viral insertions, expression signatures, viral expressions and miRNA regulation of transcripts. Results: To date we have accrued 80 cases of BL of which 75% passed diagnostic pathology review. There was an additional 25% attrition at the tissue processing stage, either due to low quality nucleic acids or low percent tumor nuclei. We have completed sequencing for 45 cases, all but one of which have a MYC translocation involving one of the 3 Ig loci; one case has a MYC rearrangement by FISH analysis that is being characterized further. We have identified recurrent mutations in ID3, DDX3X, ARID1A, FOXO1, TP53, SMARCA4 and other genes. Most mutations are supported by the RNA-seq data, which is also useful in defining the pattern of EBV genome transcription. Preliminary unsupervised hierarchical clustering and principal component analysis of gene expression data defined sample clusters that do not correspond to mutation status or EBV infection, warranting further investigation. Some genes accumulated somatic mutations in a BL subtype-specific fashion. Discussion: BLGSP is an ongoing international collaborative project that will provide a comprehensive molecular portrait of BL subtypes when completed, with the potential to suggest new molecular targets for therapy that can eventually lead to effective treatments that are less toxic than the current regimens. Disclosures Casper: Janssen: Consultancy, Research Funding; Roche: Consultancy, Other: Travel, Accommodation, Expenses; TempTime: Consultancy, Other: Travel, Accommodation, Expenses; Up to Date: Patents & Royalties; GSK: Other: Travel, Accommodation, Expenses. Abramson:Kite Pharma: Consultancy; Abbvie: Consultancy; Seattle Genetics: Consultancy; Gilead: Consultancy. Noy:Pharmacyclics, LLC, an AbbVie Company: Other: travel, accommodations, expenses, Research Funding.

Introduction: DLBCL is biological and clinically highly heterogeneous. Although different genetic aberrations, including recurrent somatic mutations, have been described in this tumor, their clinical impact remains to be clarified. The aim of the present study was to determine somatic mutations and copy number alterations of a selected group of genes in patients with DLBCL, in order to assess their prognostic importance and to identify potential personalized targeted drugs for these patients. Methods: 150 patients (78M/72F; median age, 66 years) diagnosed with de novo DLBCL no otherwise specified at Hospital Clínic and other institutions of the GELCAB, treated with immunochemotherapy, were included in the study. An independent series of 111 patients (54M/57F; median age, 63 years), diagnosed at different Japanese and Spanish institutions, was used to validate the significant findings. Targeted next generation sequencing (NGS) of 106 representative genes related with DLBCL and Copy Number Alterations (CNA) assessment were performed. Ten functional pathways were pre-defined, including NOTCH, tumor suppressor genes, JAK/STAT, epigenome/chromatic modifier, BCR signaling, PI3K-AKT-mTOR, MAP-kinase, B-cell differentiation, immune surveillance and cell cycle alterations. Cell of origin (COO) of the tumors was established using gene expression or the Lymph2Cx assay. Genomic-guided potential therapeutic opportunities for each patient were identified in silico by a Cancer Genome Interpreter platform. Results: A total of 765 potential driver mutations were identified in 89 of the 106 genes with a slightly higher number in germinal center B-cell like (GCB) than activated B-cell-like (ABC) DLBCL subtype. The most frequently mutated genes found in >15% of the cases were KMT2D (MLL2), MYD88, CREBBP and TP53, with other 27 genes being mutated in >5% of the cases. Several genes were differentially mutated in GCB DLBCL subtype (KMT2D, CREBBP, TNFRSF14, B2M, EZH2, GNA13, FOXO1, ACTB and SOCS1) or ABC subtype (MYD88, PIM1, CD79B and PRDM1). No relevant differences were observed in the clinical features according to individual mutations or CNA. No single gene mutation predicted response to therapy. Genetic alterations in KLHL6, ETV6, SGK1, L8q12.1, CD79B, PIM1 and TP53 predicted poor OS, whereas mutations of SOCS1 were associated with better outcome. Alterations in NOTCH pathway and tumor suppressor pathway were associated with poor outcome, whereas those of JAK/STAT pathway showed favorable prognosis (see table for detailed data). NOTCH pathway (HR 2.8; p=0.006) and tumor suppressor pathway (HR 2.4; p=0.005) maintained independent significance for OS along with R-IPI (H 4.0; p=0.006) in a multivariate analysis that also included COO and beta2-microglobulin. In addition, the prognostic value of NOTCH and tumor suppressor pathways was confirmed in the independent validation series. Finally, we identified 69 cases (46%) carrying at least one genomic alteration in 9 genes considered a biomarker of drug response supported by data of early clinical trials or pre-clinical assays; tumors of additional 26 patients (17%) had at least one gene alteration that could be exploited by a drug repurposing strategy. Conclusions: Integrating the deep sequencing analysis of a panel of selected genes and CNA, we have recognized novel target genes and defined the clinical relevance of alterations of NOTCH and tumor suppressor pathways in DLBCL. Using an in silico prescription pipeline we have also identified a number of candidate drugs with potential therapeutic interactions with driver oncogenic proteins. All these findings may orient future preclinical and clinical intervention strategies in DLBCL. Table Initial features, response to therapy and outcome according to pathways´ status Table. Initial features, response to therapy and outcome according to pathways´ status Disclosures Sancho: Celltrion, Inc: Research Funding; Gilead: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Gonzalez Barca:Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Speakers Bureau; Gilead: Speakers Bureau. Ohshima:Kyowa Hakko Kirin Co., Ltd.: Research Funding, Speakers Bureau; CHUGAI PHARMACEUTICAL CO.,LTD.: Research Funding, Speakers Bureau. Akashi:Sunitomo Dainippon Pharma: Consultancy; Celgene: Research Funding; Kyowa Hakko Kirin: Consultancy, Research Funding; Bristol Meyers Squibb: Research Funding; Asahi Kasei Pharma Corporation: Research Funding; Chugai Pharmaceutical Co., Ltd.: Research Funding; Shionogi & Co., Ltd: Research Funding; Astellas Pharma: Research Funding.

Burkitt's lymphoma (BL) can often be cured by intensive chemotherapy, but the toxicity of such therapy precludes its use in the elderly and in patients with endemic BL in developing countries, necessitating new strategies(1). The normal germinal centre B cell is the presumed cell of origin for both BL and diffuse large B-cell lymphoma (DLBCL), yet gene expression analysis suggests that these malignancies may use different oncogenic pathways(2). BL is subdivided into a sporadic subtype that is diagnosed in developed countries, the Epstein-Barr-virus-associated endemic subtype, and an HIV-associated subtype, but it is unclear whether these subtypes use similar or divergent oncogenic mechanisms. Here we used high-throughput RNA sequencing and RNA interference screening to discover essential regulatory pathways in BL that cooperate with MYC, the defining oncogene of this cancer. In 70% of sporadic BL cases, mutations affecting the transcription factor TCF3 (E2A) or its negative regulator ID3 fostered TCF3 dependency. TCF3 activated the pro-survival phosphatidylinositol-3-OH kinase pathway in BL, in part by augmenting tonic B-cell receptor signalling. In 38% of sporadic BL cases, oncogenic CCND3 mutations produced highly stable cyclin D3 isoforms that drive cell cycle progression. These findings suggest opportunities to improve therapy for patients with BL.

At great human cost, cancer is the largest genetic experiment ever conducted. This review highlights how lymphoid malignancies have genetically perverted normal immune signaling and regulatory mechanisms for their selfish oncogenic goals of unlimited proliferation, perpetual survival and evasion of the immune response.

Primary CNS lymphoma (PCNSL), the intracerebral subgroup of diffuse large B cell lymphoma (DLBCL), shows evidence for aberrant activation of the nuclear factor (NF)-kappaB pathway. In order to identify potential activators of the NF-kappaB complex, we analyzed the CARD11 and TNFAIP3 genes for the presence of somatic mutations and TNFAIP3 for aberrant promoter methylation in PCNSL. We also compared PCNSL to spinal DLBCL, because CARD11 and TNFAIP3 mutations have been described in systemic DLBCL. CARD11 mutations, located in the coiled-coil region, which may activate NF-kappaB, were detected in 16% (5/32) of PCNSL, while TNFAIP3 mutations were detected in 3% (1/32) of PCNSL. In PCNSL, all CARD11 mutations were heterozygous, in-frame, induced amino acid exchanges, and presumably led to activation of this oncogene. Spinal DLBCL harbored mutations of CARD11 and TNFAIP3 in 10% (1/10) and 20% (2/10) of cases, respectively. In both PCNSL and spinal DLBCL, mutations in CARD11 and TNFAIP3 were mutually exclusive. TNFAIP3 was unmethylated in all PCNSLs (30/30) and spinal DLBCLs (10/10). We conclude that mutations of the oncogene CARD11 may contribute to NF-kappaB activation and thereby play a role in the pathogenesis of PCNSL, while, in contrast to systemic DLBCL, inactivation of TNFAIP3 either by mutation or methylation seems to be of minor significance.

Hodgkin and Reed-Sternberg (HRS) cells in classical Hodgkin lymphoma (HL) and lymphocytic and histiocytic (L&H) cells in nodular lymphocyte–predominant HL (NLPHL) are derived from germinal-center B cells. HRS cells have, however, largely lost their B cell phenotype and aberrantly express markers and transcriptional regulators of other hematolymphoid cell types. Deregulation of multiple signaling pathways and downstream transcription factors, including receptor tyrosine kinases, nuclear factor–kappa B (NF-κB), and Janus kinase/signal transducer and activator of transcription (JAK/STAT), is a further hallmark of HRS cells. These cells harbor genetic lesions that contribute to or cause increases in the activity of transcription factors of the NF-κB and STAT families. HRS cells are found within a mixed reactive cellular infiltrate and interact with these nonmalignant cells in a complex fashion that appears to be essential for HRS cell survival and proliferation. Less is known about the pathogenesis of L&H cells in NLPHL, but increases in the activity of receptor tyrosine kinases, NF-κB, and JAK/STAT have also been detected.

Proliferation and survival of Hodgkin and Reed/Sternberg (HRS) cells, the malignant cells of classical Hodgkin lymphoma (cHL), are dependent on constitutive activation of nuclear factor kappaB (NF-kappaB). NF-kappaB activation through various stimuli is negatively regulated by the zinc finger protein A20. To determine whether A20 contributes to the pathogenesis of cHL, we sequenced TNFAIP3, encoding A20, in HL cell lines and laser-microdissected HRS cells from cHL biopsies. We detected somatic mutations in 16 out of 36 cHLs (44%), including missense mutations in 2 out of 16 Epstein-Barr virus-positive (EBV(+)) cHLs and a missense mutation, nonsense mutations, and frameshift-causing insertions or deletions in 14 out of 20 EBV(-) cHLs. In most mutated cases, both TNFAIP3 alleles were inactivated, including frequent chromosomal deletions of TNFAIP3. Reconstitution of wild-type TNFAIP3 in A20-deficient cHL cell lines revealed a significant decrease in transcripts of selected NF-kappaB target genes and caused cytotoxicity. Extending the mutation analysis to primary mediastinal B cell lymphoma (PMBL), another lymphoma with constitutive NF-kappaB activity, revealed destructive mutations in 5 out of 14 PMBLs (36%). This report identifies TNFAIP3 (A20), a key regulator of NF-kappaB activity, as a novel tumor suppressor gene in cHL and PMBL. The significantly higher frequency of TNFAIP3 mutations in EBV(-) than EBV(+) cHL suggests complementing functions of TNFAIP3 inactivation and EBV infection in cHL pathogenesis.

High expression of CC chemokine receptor 4 (CCR4) has been identified as a hallmark gene in ATLL, an aggressive peripheral T-cell neoplasm. CCR4 is a chemokine receptor, which has a critical role in immune cell trafficking. CCR4 ligands, CCL17 and CCL22, were produced in lymph nodes and skin from dendritic cells, macrophages and Langerhans cells. Most ATLL cases express surface CCR4 (90%) and infiltrate to lymph nodes and skin. These observations suggest that CCR4 could have a role in ATLL biology, but it is still unclear whether dysregulation of CCR4 function contributes to ATLL pathogenesis. We performed RNA-Seq for two primary ATLL cases and discovered recurrent non-sense mutations in CCR4. Though an extended analysis using Sanger sequencing, CCR4 mutations were detected in 14/53 ATLL samples (26%) and consisted exclusively of nonsense or frameshift mutations that truncated the coding region at C329, Q330 or Y331 in the carboxy-terminus. In 5 cases for which paired normal DNA was available, three different CCR4 mutations were detected only in the ATLL cells (Q330*; Q330 frameshift; Y331*), demonstrating that they were acquired somatically during malignant transformation or progression. Chemotaxic assay using 32Dβ, a mouse myeloid cell line, and ED40515(+), an ATLL cell line, clarified that the ectopic expression of CCR4-Q330* enhanced the chemotactic ability of the transduced cells toward CCL17 and CCL22 rather than CCR4-WT transduced cells. To understand the mechanism of this enhanced chemotactic ability, we studied the change in surface CCR4 levels after CCL22 exposure in CCR4-WT-and CCR4-Q330*-reconstituted ED40515(+) cells. Compared with CCR4-WT, CCR4 internalization in CCR4-Q330*-reconstituted cells was significantly impaired. Thus, the ATLL CCR4 mutants impair desensitization by ligand, which likely contributes to the enhanced chemotaxis of cells bearing these mutants. We explored the influence of the ATLL CCR4 mutants on PI3K/AKT signaling by immunoblot analysis and phosphor-flow analysis. CCR4-Q330*-reconstituted ED40515(+) showed strong activation of AKT with CCL22 ligation compared with CCR4-WT-reconstituted cell. Furthermore, we tested whether the acquisition of CCR4 mutations by ATLL cells imparts a selective growth advantage relative to cells with wild type CCR4. CCR4-Q330*-reconstituted cells had a selective growth advantage in the presence of CCL22, supporting at least in part the hypothesis that CCR4 mutation are able to provide the affected cells a positive selection pressure through CCL22 ligation and contributes to ATLL pathogenesis. Our findings implicate somatic gain-of-function CCR4 mutations in the pathogenesis of ATLL and suggest that inhibition of CCR4 signaling might have therapeutic potential in this refractory malignancy. Citation Format: Masao Nakagawa, Roland Schmitz, Wenming Xiao, Carolyn K. Goldman, Weihong Xu, Yandan Yang, Xin Yu, Thomas A. Waldmann, Louis M. Staudt. Frequent gain-of-function CCR4 mutations in adult T-cell leukemia/lymphoma (ATLL). [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 3936. doi:10.1158/1538-7445.AM2015-3936

Members of the BCL-2 gene family are well known for their role in the pathogenesis of B-cell lymphomas in humans and in mouse models. A recent report that knockout mice deficient for the proapoptotic BCL-2 family member gene BAD frequently develop B-cell lymphomas prompted us to analyze a large collection of human B-cell lymphomas for inactivating mutations in the BAD gene. All 3 exons of the BAD gene were amplified and directly sequenced. The 81 lymphomas analyzed included 16 cases of B-cell chronic lymphocytic leukemia, 11 mantle-cell lymphomas, 10 follicular lymphomas, 7 MALT lymphomas, 8 Burkitt's lymphoma cell lines, 3 cell lines of multiple myeloma, 15 cases and 4 cell lines of diffuse large B-cell lymphoma and 7 Hodgkin's lymphoma lines. No mutations were found in any of the cases. We conclude that mutations in the BAD gene do not play a role in the pathogenesis of the major subtypes of human B-cell lymphomas.

Clonally related composite lymphomas of Hodgkin's lymphoma (HL) and Non-Hodgkin's lymphoma (NHL) represent models to study the multistep transformation process in tumorigenesis and the development of two distinct tumors from a shared precursor. We analyzed six such lymphomas for transforming events. The HLs were combined in two cases with follicular lymphoma (FL), and in one case each with B-cell chronic lymphocytic leukemia, splenic marginal zone lymphoma, mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL). In the HL/FL and HL/MCL combinations, BCL2/IGH and CCND1/IGH translocations, respectively, were detected in both the HL and NHL. No mutations were found in the tumor suppressor genes FAS, NFKBIA and ATM. The HL/DLBCL case harbored clonal replacement mutations of the TP53 gene on both alleles exclusively in the DLBCL. In conclusion, we present the first examples of molecularly verified IgH-associated translocations in HL, which also show that BCL2/IGH or CCND1/IGH translocations can represent early steps in the pathogenesis of composite HL/FL or HL/MCL. The restriction of the TP53 mutations to the DLBCL in the HL/DLBCL case exemplifies a late transforming event that presumably happened in the germinal center and affected the fate of a common lymphoma precursor cell towards development of a DLBCL.

Apoptosis-resistant phenotype of classical Hodgkin's lymphoma is not mediated by somatic mutations within genes encoding members of the death-inducing signaling complex (DISC)

To determine in a prospective controlled trial the effect of percutaneous transluminal angioplasty (PTA) on skin oxygen supply and microcirculation as measured by means of transcutaneous oxygen pressure in patients with disabling lower-limb ischemia compared with that in patients who underwent intraarterial angiography for the assessment of disabling lower-limb ischemia.Thirty-four patients (17 men, 17 women; mean age, 68.6 years +/- 9.8 [SD]) with peripheral arterial occlusive disease (PAOD) (claudication, n = 15; critical ischemia, n = 19) underwent transcutaneous oxygen pressure measurement at the dorsum of the foot 1 day before PTA, during PTA, 1 day after PTA, and 6 weeks after PTA. Measurements were obtained with the patient in the supine and erect sitting positions, as well as after exercise. Thirty-one patients (21 men, 10 women; mean age, 68.5 years +/- 9.3) with symptomatic PAOD who were undergoing intraarterial angiography served as the control group.Mean pressure before PTA was 31.6 mm Hg +/- 24 in the supine position, 50.8 mm Hg +/- 22 in the sitting position, and 22.2 mm Hg +/- 23 after exercise. Immediately after PTA, a significant increase to 34 mm Hg +/- 20 in the supine position was noted (P.05). One day after PTA, pressure was 37.3 mm Hg +/- 20 for the supine position and 52 mm Hg +/- 20 for the sitting position. Six weeks after treatment, a further significant increase to 43.9 mm Hg +/- 19 in the supine position, 61 mm Hg +/- 15 in the sitting position, and 44.7 mm Hg +/- 24 after exercise was noted (P.05). In the control group, a significant pressure decrease immediately after and 1 day after angiography was noted (P.05). Measurements returned to baseline at 6 weeks follow-up.PTA has a positive effect on oxygen supply to the skin in patients with PAOD. Conversely, intraarterial angiography in patients with PAOD deteriorates skin microcirculation temporarily.

High expression of CC chemokine receptor 4 (CCR4) has been identified as a hallmark gene in ATLL, an aggressive peripheral T-cell neoplasm. CCR4 is a chemokine receptor, which has a critical role in immune cell trafficking including Th2, T-reg and skin-homing memory T-cells. CCR4 ligands, CCL17 and CCL22, were produced in lymph nodes and skin from dendritic cells, macrophages and Langerhans cells. Most ATLL cases express surface CCR4 (90%) and infiltrate to lymph nodes and skin. These observations suggest that CCR4 could have a role in ATLL biology, but it is still unclear whether dysregulation of CCR4 function contributes to ATLL pathogenesis. We performed RNA-Seq for two primary ATLL cases and discovered recurrent non-sense mutations in CCR4. Though an extended analysis using Sanger sequencing, CCR4 mutations were detected in 14/53 ATLL samples (26%) and consisted exclusively of nonsense or frameshift mutations that truncated the coding region at C329, Q330 or Y331 in the carboxy-terminus. We noticed that the location of the CCR4 mutations in ATLL were reminiscent of mutations affecting the chemokine receptor CXCR4 in the WHIM syndrome, a human immunodeficiency disease. Most CXCR4 mutations in the WHIM syndrome are nonsense or frameshift, resulting in carboxy-terminal truncation of the protein and conferring a gain-of-function phenotype with respect to chemotaxis towards the CXCR4 ligand SDF1. We therefore hypothesized that mutant CCR4 isoforms might enhance chemotaxis of the affected cells to CCR4 ligands. Chemotaxic assay using 32Db, a mouse myeloid cell line, and ED40515(+), an ATLL cell line, clarified that the ectopic expression of CCR4-Q330* enhanced the chemotactic ability of the transduced cells toward CCL17 and CCL22 rather than CCR4-WT transduced cells with statistical significance. To understand the mechanism of this enhanced chemotactic ability, we studied the change in surface CCR4 levels after CCL22 exposure in CCR4-WT-and CCR4-Q330*-reconstituted ED40515(+) cells. Compared with CCR4-WT, CCR4 internalization in CCR4-Q330*-reconstituted cells was significantly impaired. Thus, the ATLL CCR4 mutants impair desensitization by ligand, which likely contributes to the enhanced chemotaxis of cells bearing these mutants. We explored the influence of the ATLL CCR4 mutants on PI(3) kinase (PI3K)-dependent activation of AKT since it has been reported that binding of CCL22 to CCR4 activates AKT in CEM leukemic T-cells and in human Th2 cells. CCR4-Q330*-reconstituted ED40515(+) showed strong activation of AKT with CCL22 ligation compared with CCR4-WT-reconstituted cell. The AKT activation was cancelled with pan-PI3K inhibitor, BKM120, indicating that CCR4-mediated AKT activation was PI3K dependent. Lastly, we tested whether the acquisition of CCR4 mutations by ATLL cells imparts a selective growth advantage relative to cells with wild type CCR4. CCR4-Q330*-reconstituted cells had a selective growth advantage in the presence of CCL22, supporting at least in part the hypothesis that CCR4 mutation are able to provide the affected cells a positive selection pressure through CCL22 ligation and contributes to ATLL pathogenesis. We discovered for the first time recurrent somatic mutations in CCR4 in ATLL. CCR4 mutations were detected in 14/53 ATLL samples (26%) and consisted exclusively of nonsense or frameshift mutations that truncated the coding region at C329, Q330 or Y331 in the carboxy-terminus. Functionally, the CCR4-Q330* was a gain-of-function since it increased cell migration towards the CCR4 ligands CCL17 and CCL22, in part by impairing receptor internalization. This mutant enhanced PI(3) kinase/AKT activation following receptor engagement by CCL22 in ATLL cells, and conferred a growth advantage in in vitro cultures. Our findings provide a rationale to test whether inhibition of CCR4 signaling might have a therapeutic potential for patients with ATLL. Disclosures No relevant conflicts of interest to declare.

686 Background DLBCL has two molecular subtypes, termed activated B cell-like (ABC) and germinal center B cell-like (GCB), with ABC DLBCL being less curable with current therapy. The survival of ABC but not GCB DLBCL cell lines is sustained by “chronic active” B cell receptor (BCR) signaling. Gain-of-function mutations affecting the BCR subunit CD79B occur in 21% of ABC but only 5% of GCB DLBCL tumors. ABC DLBCL cell lines also depend upon a second pathway for survival that is coordinated by MYD88, an adapter for Toll-like receptors. A constitutively active MYD88 mutant (L265P) is frequent in ABC DLBCL tumors (29%) but rare in GCB DLBCL. CD79B and MYD88 L265P mutations often coexist in ABC DLBCL tumors, suggesting oncogenic collaboration, but can also occur alone. Here, we present interim results of a phase 2 study in relapsed/refractory DLBCL of ibrutinib, a first in class inhibitor of BTK, a kinase in the BCR pathway. We tested the hypothesis that ibrutinib would be more active in ABC than GCB DLBCL due to their different addiction pathways, and we assessed the association of CD79B and MYD88 mutations with response. Methods Subjects with relapsed/refractory de novo DLBCL received ibrutinib 560 mg PO QD. Gene expression profiling (GEP) of formalin-fixed paraffin-embedded biopsy tissues using Affymetrix arrays was used to identify the DLBCL subtype (ABC, GCB, unclassifiable) or were not arrayed (unknown). Sanger sequencing was used to identify CD79B and MYD88 mutations. Subjects underwent CT and PET scanning pre-treatment and every 2 cycles. The primary objective of the study was overall response rate (ORR) categorized by molecular subtype. Response was investigator determined using the revised International Working Group Criteria for NHL. Subjects Seventy subjects were enrolled; median age 63 yrs (28–92); male 71%; stage IV 63%; HI-I/HI IPI 59%; disease ≥10 cm 23%; median prior systemic therapies 3 (1–7); relapsed (27%), refractory (54%) and unknown (19%); prior stem cell transplant 23%; and median time from diagnosis 19 months. Results Safety data are available for 68 subjects who received ≥ 1 dose of ibrutinib. Ibrutinib was well tolerated, with treatment-emergent AEs consistent with data reported in other ibrutinib studies. No new safety signals were identified. Sixty subjects were evaluable per protocol for response (≥ 1 dose of ibrutinib and at least one response assessment). Four subjects in the ABC cohort were not evaluable for response (1 death at study day 12, 1 PD at study day 65, and 2 remain on study treatment but have not had their first response assessment at this analysis). One subject in the GCB cohort was not evaluable for response (death at study day 41). In the ABC subtype, per protocol ORR was 40% (10/25, 95% CI: 21–61%), CR 8% (2/25) and PR 32% (8/25). The median PFS at the time of this analysis is 5.5 months in ABC responders with 60% having not progressed (5 remain on treatment and 1 responder proceeded to transplant). Only one PR was observed in the GCB subtype and none in unclassifiable cases. Thus, ibrutinib showed preferential response activity in ABC versus GCB DLBCL (p=0.0126, Fisher's exact test). Responses occurred in ABC DLBCL tumors with CD79B mutations (60%; 3/5), but also in those with wild type CD79B (37%; 7/19), suggesting that ibrutinib sensitivity does not require a BCR mutation. All cases with both CD79B and MYD88 L265P mutations (n=4) responded, showing that the MYD88 pathway does not prevent ibrutinib activity. In comparison, tumors with only a MYD88 L265P mutation (n=4) did not respond (p=0.0286, Fisher's exact test), suggesting a MYD88-dependent but BCR-independent pathogenesis for some ABC DLBCL cases. | | ABC subtype (N=29) | GCB subtype (N=20) | Unclassifiable[1][1] (N=16) | Unknown[2][2] (N=5) | Total (N=70) | |:-------------------------- | ------------------ | ------------------ | --------------------------- | ------------------- | ------------ | | Not Evaluable for Response | 4 | 1 | 3 | 2 | 10 | | PP ORR[4][3] (CR + PR) | 10 (40%) | 1 (5.3%) | | 2 (66.7%) | 13 (21.7%) | | Complete Response (CR) | 2 (8%) | | | 1 (33.3%) | 3 (5%) | | Partial Response (PR) | 8 (32%) | 1 (5.3%) | | 1 (33.3%) | 10 (16.7%) | | PFS (months) | 2.5 | 1.28 | 0.95 | NR[3][4] | 1.64 | * [↵][5]1 GEP performed, but not assignable to ABC or GCB subtypes. * [↵][6]2 GEP not yet performed or tissue not available. * [↵][7]3 Not reached. * [↵][8]4 PP = per protocol. Efficacy Data Conclusions Ibrutinib showed a clinically meaningful response rate in relapsed/refractory ABC DLBCL, but not in other molecular subtypes. These results are consistent with an essential role of BCR signaling in ABC DLBCL and indicate that future clinical trials of ibrutinib in DLBCL should enroll patients with this subtype. Disclosures: Goy: Pharmacyclics: Research Funding. de Vos: Pharmacyclics: Research Funding. Kenkre: Pharmacyclics: Research Funding. Blum: Pharmacyclics: Research Funding. Advani: Phramacyclics, Inc: Research Funding. Kunkel: Pharmacyclics, Inc: Employment, Equity Ownership. McGreivy: Pharmacyclics, Inc.: Employment, Equity Ownership. Balasubramanian: Pharmacyclics, Inc.: Employment, Equity Ownership. Cheng: Pharmacyclics, Inc.: Employment, Equity Ownership. Moussa: Pharmacyclics, Inc.: Employment, Equity Ownership. Buggy: Pharmacyclics, Inc.: Employment, Equity Ownership. [1]: #fn-1 [2]: #fn-2 [3]: #fn-4 [4]: #fn-3 [5]: #xref-fn-1-1 [6]: #xref-fn-2-1 [7]: #xref-fn-3-1 [8]: #xref-fn-4-1

Abstract 2716 Background Btk is a tyrosine kinase involved in B cell receptor (BCR) signal transduction. Recent studies indicate that chronic active BCR signaling is a pathogenic mechanism in ABC DLBCL that engages the classical NF-κB pathway. Mutations in the BCR pathway (CD79A/B and CARD11) and toll like receptor (TLR) pathway (MYD88) lead to constitutive NF-κB activation in ABC DLBCL. PCI-32765 kills ABC DLBCL cell lines with constitutive BCR signaling but has no effect on ABC and GBC DLBCL cell lines that do not rely on constitutive BCR signaling. PCI-32765 is an oral, well-tolerated and irreversible inhibitor of Btk. Study Design Patients with relapsed/refractory ABC DLBCL received PCI-32765 at a fixed dose of 560 mg po once daily × 35 days (1 cycle). Patients underwent CT and FDG-PET scanning pre-treatment and every 2 cycles. Where possible, pre-treatment and 48-hour post-treatment tumor biopsies were performed for gene expression profiling (GEP) and mutational analysis of CD79A/B, CARD11 and MYD88. Results Eight of 15 planned patients are enrolled. Characteristics include median (range) age 54 (40–79); LDH > normal limits (63%); any extranodal site (75%) and stage 4 disease (63%). IPI distribution was 0–2 (25%) and 3–5 (75%). Patients received a median (range) of 3 (1–6) prior chemotherapy regimens. Best response by IWG criteria include CR: 2 (25%) for 11+ and 5 months; SD (stable disease) 3 (37%) for 4, 2 and 2 months; and PD (progressive disease) 3 (38%). One patient who was primary refractory achieved SD with PCI-32765, associated with a 25% tumor reduction, and is currently in CR following allogeneic BMT. PCI-32765 was well-tolerated without significant side effects. No patients discontinued PCI-32765 due to AE. Grade >3 AEs were reported in 4 patients, none were considered related to PCI-32765. One death has occurred on study, in a patient who received subsequent therapy following progression on PCI-32765. Toxicities that are possibly related to PCI-32765 include diarrhea (grade 1) in 2 patients, nausea (grade 1) in 2 patients and fatigue (grades 1–2) in 4 patients. CD79B mutations were uncovered in two patients, the patient with SD who achieved a 25% tumor response and one patient who achieved CR. Of note, the other patient who achieved CR did not have the CD79B mutation, suggesting that chronic active BCR signaling may occur in the absence of this mutation. None of the patients had MYD88 or CARD11 mutations. Comparison of the pre-treatment and on-treatment biopsy samples by gene expression profiling was completed on 5 patients (1 CR, 4 SD/PD). Gene expression signatures reflecting tumor infiltrating immune cells, including CD8+ T cells and macrophages, were diminished by PCI-32765 treatment in the one patient in CR and the one patient in SD who achieved a 25% tumor reduction, but not in the others. In these same two cases, a gene expression signature of interferon signaling was reduced upon PCI-32765 treatment, associated with a concomitant decrease in interferon gamma mRNA levels, again suggesting the loss of activated T cells in the responding tumors. One hypothesis to explain this observation would be cytokine modulation since chronic active BCR signaling promotes synthesis and secretion of IL-10 and multiple chemokines, including CXCL13, CXCL9 and CCL3, which were all down-modulated in the responding tumors. Conclusions The Btk inhibitor PCI-32765 has clinical activity in relapsed/refractory ABC DLBCL and modulates chronic active BCR signaling in responders. Thus, chronic active BCR signaling is a tractable therapeutic target in ABC DLBCL. Disclosures: Buggy: Pharmacyclics, Inc.: Employment. Hedrick:Pharmacyclics: Employment, Equity Ownership.

Abstract 435 The recent development of high throughput mRNA sequencing technologies has allowed major advances in the characterization and quantification of transcriptomes in human cancer. These advances include gene mutation detection, gene fusion discovery, analysis of alternative splicing events, and unbiased gene expression profiling. To comprehensively discover pathogenic sequence variants in lymphomas, we used Illumina technology to sequence mRNA of 206 lymphoma biopsies and cell lines, including 64 diffuse large B-cell lymphomas (DLBCL) of the activated B-cell-like (ABC) subtype, 71 DLBCL of the germinal center (GCB) subtype, and 41 Burkitt's lymphomas (BL). This effort uncovered a large number of mutations that were verified by Sanger sequencing. Using this methodology, we discovered somatic mutations in CCND3, encoding Cyclin D3, in 38 % of BLs, 14 % of ABC DLBCLs, and 10 % of GCB DLBCLs. These mutations stabilized the Cyclin D3 protein by altering a phosphorylation motif at Thr283 that is required for proteasomal degradation. Knockdown of CCND3 by RNA interference confirmed the oncogenic addiction to this gene in the mutated cell lines. In parallel, an RNA interference screen revealed that the cell lines that are dependent on CCND3 are also reliant on cyclin-dependent kinase 6 (CDK6), which together with Cyclin D3 regulates the G1/S transition of the cell cycle. Ectopic expression of the mutant CCND3 isoforms accelerated lymphoma cell line proliferation thereby demonstrating the oncogenic potential of these mutations. Remarkably, treatment of the CCND3/CDK6 addicted cell lines with a small molecule inhibitor of CDK 4/6 caused G1 arrest followed by apoptosis suggesting novel therapeutic strategies for these aggressive lymphomas. Disclosures: No relevant conflicts of interest to declare.

Germinal centre B-cell-like diffuse large B-cell lymphoma (GCB-DLBCL) is a common malignancy, yet the signalling pathways that are 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 germinal centre B cells3,4. Recent deep sequencing studies of GCB-DLBCL have revealed mutations in many genes in this cancer, including in GNA13 (encoding Gα13) and S1PR2 (refs 5,6, 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 germinal centre B cells and human GCB-DLBCL cells were unable to suppress pAkt and migration in response to S1P, and Gα13-deficient mice developed germinal centre B-cell-derived lymphoma. Germinal centre B cells, unlike most lymphocytes, are tightly confined in lymphoid organs and do not recirculate. Remarkably, deficiency in Gα13, but not S1PR2, led to germinal centre 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 germinal centre 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 germinal centre B-cell-derived malignancy, Burkitt's lymphoma, also represses germinal centre 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 germinal centre B cells that is frequently disrupted in germinal centre B-cell-derived lymphoma.