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SAMHD1 is a deoxynucleoside triphosphate triphosphohydrolase (dNTPase) that restricts viral replication in infected cells and limits the sensitivity to cytarabine by hydrolysing its active metabolite, as recently shown in acute myeloid leukemia. Cytarabine is an essential component in the Nordic mantle cell lymphoma protocols (MCL2 and MCL3) for induction and high-dose chemotherapy treatment before autologous stem cell transplantation for younger patients with mantle cell lymphoma (MCL). We here investigated the expression of SAMHD1 in a population-based cohort of MCL (N = 150). SAMHD1 was highly variably expressed in MCL (range, 0.4% to 100% of positive tumor cells). Cases with blastoid/pleomorphic morphology had higher SAMHD1 expression (P = 0.028) and SAMHD1 was also correlated to tumor cell proliferation (P = 0.016). SAMHD1 expression showed moderate correlation to the expression of the transcriptional regulator SOX11 (P = 0.036) but genetic silencing of SOX11 and SAMHD1 by siRNA in MCL cell lines did not suggest mutual regulation. We hypothesized that expression of SAMHD1 could predict short time to progression in patients treated with Cytarabine as part of high-dose chemotherapy. Despite the correlation with known biological adverse prognostic factors, neither low or high SAMHD1 expression correlated to PFS or OS in patients treated according to the Nordic MCL2 or MCL3 protocols (N = 158).

To survive chemotherapy, lymphoma cells can relocate to protective niches where they receive support from the non-malignant cells. The biolipid 2-arachidonoylglycerol (2-AG), an agonist for the cannabinoid receptors CB1 and CB2, is released by stromal cells in the bone marrow. To investigate the role of 2-AG in lymphoma, we analyzed the chemotactic response of primary B-cell lymphoma cells enriched from peripheral blood of twenty-two chronic lymphocytic leukemia (CLL) and five mantle cell lymphoma (MCL) patients towards 2-AG alone and/or to the chemokine CXCL12. The expression of cannabinoid receptors was quantified using qPCR and the protein levels visualized by immunofluorescence and Western blot. Surface expression of CXCR4, the main cognate receptor to CXCL12, was analyzed by flow cytometry. Phosphorylation of key downstream signaling pathways activated by 2-AG and CXCL12 were measured by Western blot in three MCL cell lines and two primary CLL samples. We report that 2-AG induces chemotaxis in 80% of the primary samples, as well as 2/3 MCL cell lines. 2-AG induced in a dose-dependent manner, the migration of JeKo-1 cell line via CB1 and CB2. 2-AG affected the CXCL12-mediated chemotaxis without impacting the expression or internalization of CXCR4. We further show that 2-AG modulated p38 and p44/42 MAPK activation. Our results suggest that 2-AG has a previously unrecognized role in the mobilization of lymphoma cells by effecting the CXCL12-induced migration and the CXCR4 signaling pathways, however, with different effects in MCL compared to CLL.

This phase II clinical trial investigates a one-time oromucosal dose of tetrahydrocannabinol/cannabidiol (THC/CBD) in 23 patients with indolent leukemic B cell lymphomas. Primary endpoint was a significant reduction in leukemic B cells. Grade 1 - 2 adverse events were seen in 91% of the patients; most common were dry mouth (78%), vertigo (70%), and somnolence (43%). After THC/CBD a significant reduction in leukemic B cells (median, 11%) occurred within two hours (

Established cell culture systems have failed to accurately recapitulate key features of terminal erythroid maturation, hampering our ability to in vitro model and treat diseases with impaired erythropoiesis such as myelodysplastic syndromes with ring sideroblasts (MDS-RS). We developed an efficient and robust three-dimensional (3D) scaffold culture model supporting terminal erythroid differentiation from both mononuclear (MNC) or CD34+-enriched primary bone marrow cells from healthy donors and MDS-RS patients. While CD34+ cells did not proliferate beyond two weeks in 2D suspension cultures, the 3D scaffolds supported CD34+ and MNC erythroid proliferation over four weeks demonstrating the importance of the 3D environment. CD34+ cells cultured in 3D facilitated the highest expansion and maturation of erythroid cells, including generation of erythroblastic islands and enucleated erythrocytes, while MNCs supported multi-lineage hemopoietic differentiation and cytokine secretion relevant for MDS-RS. Importantly, MDS-RS 3D-cultures supported de novo generation of ring sideroblasts and maintenance of the mutated clone. The 3D cultures effectively model a clonal disease characterized by terminal erythroid failure and can be used to assess therapeutic compounds.

Angioimmunoblastic T-cell lymphoma (AITL) is characterized by poor prognosis and low response rate to conventional chemotherapy [1]. Genotyping has revealed a high frequency of mutations in genes i...

Mantle cell lymphoma (MCL), a malignancy of B-lymphocytes, has a poor prognosis. It is thus necessary to improve the understanding of the pathobiology of MCL and identify factors contributing to its aggressiveness. Our studies, based on Affymetrix data from 17 MCL biopsies, real-time quantitative polymerase chain reaction data from 18 sorted primary MCL cells and 108 MCL biopsies compared to non-malignant tissue, reveals that GNAZ expression predicts poor clinical outcome of MCL patients (Cox regression, P = 0·014) and lymphocytosis (Mann-Whitney, P = 0·011). We show that GNAZ translates to Gαz protein - a signalling molecule within the G-protein coupled receptor network. Our findings suggest that GNAZ/Gαz contribute to the MCL pathobiology.

Mechanisms for late-onset neutropenia (LON) after rituximab treatment are poorly defined both for non-Hodgkin lymphoma (NHL) and for autoimmune disorders. We performed a case–control analysis of a prospective cohort of 169 evaluable consecutive rituximab-treated NHL patients to assess cytokines involved in neutro- and lymphopoiesis (G-CSF, SDF1, BAFF, APRIL) and inflammation (CRP) as possible LON mechanisms. Fifteen patients (9%) developed LON (peripheral blood /PB/ absolute neutrophil counts /ANC/

A subset of hematologic cancer patients is refractory to treatment or suffers relapse, due in part to minimal residual disease, whereby some cancer cells survive treatment. Cell-adhesion-mediated drug resistance is an important mechanism, whereby cancer cells receive survival signals via interaction with e.g. stromal cells. No genome-wide studies of in vitro systems have yet been performed to compare gene expression in different cell subsets within a co-culture and cells grown separately. Using RNA sequencing and species-specific read mapping, we compared transcript levels in human Jeko-1 mantle cell lymphoma cells stably adhered to mouse MS-5 stromal cells or in suspension within a co-culture or cultured separately as well as in stromal cells in co-culture or in separate culture. From 1050 differentially expressed transcripts in adherent mantle cell lymphoma cells, we identified 24 functional categories that together represent four main functional themes, anti-apoptosis, B-cell signaling, cell adhesion/migration and early mitosis. A comparison with previous mantle cell lymphoma and chronic lymphocytic leukemia studies, of gene expression differences between lymph node and blood, identified 116 genes that are differentially expressed in all three studies. From these genes, we suggest a core set of genes (CCL3, CCL4, DUSP4, ETV5, ICAM1, IL15RA, IL21R, IL4I1, MFSD2A, NFKB1, NFKBIE, SEMA7A, TMEM2) characteristic of cells undergoing cell-adhesion-mediated microenvironment signaling in mantle cell lymphoma/chronic lymphocytic leukemia. The model system developed and characterized here together with the core gene set will be useful for future studies of pathways that mediate increased cancer cell survival and drug resistance mechanisms.

Human B-lymphocytes express 5-lipoxygenase (5-LOX) and 5-LOX activating protein (FLAP) and can convert arachidonic acid to leukotriene B4. Mantle cell lymphoma (MCL) cells contain similar amounts of 5-LOX as human neutrophils but the function and mechanism of activation of 5-LOX in MCL cells, and in normal B-lymphocytes, are unclear. Here we show that the intrinsic 5-LOX pathway in the MCL cell line JeKo-1 has an essential role in migration and adherence of the cells, which are important pathophysiological characteristics of B-cell lymphoma. Incubation of JeKo-1 with the FLAP inhibitor GSK2190915 or the 5-LOX inhibitor zileuton, at a concentration below 1 μM, prior to stimulation with the chemotactic agent CXCL12, led to a significant reduction of migration. CRISPR/Cas9 mediated deletion of ALOX5 gene in JeKo-1 cells also led to a significantly decreased migration of the cells. Furthermore, 5-LOX and FLAP inhibitors markedly decreased the adherence of JeKo-1 cells to stromal cells. In comparison, these drugs had a similar effect on adherence of JeKo-1 cells as the Bruton tyrosine kinase inhibitor ibrutinib, which has a proven anti-tumour effect. These results indicate that inhibition of 5-LOX may be a novel treatment for MCL and certain other B-cell lymphomas.

PURPOSE MYC rearrangement ( MYC-R) occurs in approximately 10% of diffuse large B-cell lymphomas (DLBCLs) and has been associated with poor prognosis in many studies. The impact of MYC-R on prognosis may be influenced by the MYC partner gene (immunoglobulin [IG] or a non-IG gene). We evaluated a large cohort of patients through the Lunenburg Lymphoma Biomarker Consortium to validate the prognostic significance of MYC-R (single-, double-, and triple-hit status) in DLBCL within the context of the MYC partner gene. METHODS The study cohort included patients with histologically confirmed DLBCL morphology derived from large prospective trials and patient registries in Europe and North America who were uniformly treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone therapy or the like. Fluorescence in situ hybridization for the MYC, BCL2, BCL6, and IG heavy and light chain loci was used, and results were correlated with clinical outcomes. RESULTS A total of 5,117 patients were identified of whom 2,383 (47%) had biopsy material available to assess for MYC-R. MYC-R was present in 264 (11%) of 2,383 patients and was associated with a significantly shorter progression-free and overall survival, with a strong time-dependent effect within the first 24 months after diagnosis. The adverse prognostic impact of MYC-R was only evident in patients with a concurrent rearrangement of BCL2 and/or BCL6 and an IG partner (hazard ratio, 2.4; 95% CI, 1.6 to 3.6; P < .001). CONCLUSION The negative prognostic impact of MYC-R in DLBCL is largely observed in patients with MYC double hit/triple-hit disease in which MYC is translocated to an IG partner, and this effect is restricted to the first 2 years after diagnosis. Our results suggest that diagnostic strategies should be adopted to identify this high-risk cohort, and risk-adjusted therapeutic approaches should be refined further.

Chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL) may share certain clinical and immune phenotypic features at diagnosis. The typical phenotype in CLL is CD19+, CD20dim+, CD79bdim+,...

Background: ROR1 - a receptor tyrosine kinase (RTK) - is essential for normal embryonic development, but is absent on most normal adult tissues. ROR1 is of importance of cell proliferation, differentiation, survival and metabolism. However, ROR1 is overexpressed in several types of cancer (onco-fetal RTK). MCL is an aggressive and incurable non-Hodgkin lymphoma characterized by translocation (11;14) (q13;q32) and cyclin D overexpression. ROR1 has been described to be highly expressed in MCL cells. We have previously presented results on a small molecule ROR1 inhibitor in CLL (KAN0439834) (Leukemia 32(10):2291, 2018). A second generation ROR1 inhibitor, KAN0441571C, has been developed with improved killing of tumor cells and with longer half-life time (>10h) (PK studies in mice/rats/dogs) compared to KAN0439834. Aim: In this study we examined effects of the ROR1 small molecule inhibitor KAN0441571C in human MCL cells (Granta-519, Jeko-1, JVM-2, Z138, Mino) as part of a pre-clinical evaluation. Methods: ROR1 expression was evaluated by flow cytometry and WB. Cytotoxicity was analysed by MTT and apoptosis by Annexin V/P staining and Western Blot for apoptotic proteins. Cytotoxicity (MTT) was also analysed by combining the ROR1 inhibitor with ibrutinib, acalabrutinib, venetoclax and bendamustine. Effects of KAN0441571C on ROR1 inactivation (dephosphorylation) and signaling pathways were evaluated by WB. Results: All five cell-lines expressed phosphorylated ROR1 (130 kDa) with a varying intensity. Surface expression (flow-cytometry) varied from 0% (JVM-2) to 100% (Mino and JeKo-1). The data indicate expression of also splice variants lacking the extracellular domain. KAN0441571C induced time and dose dependent apoptosis of the five MCL cell-lines which was p53 independent. EC50 varied between 100-250 nM (24h). Apoptosis was confirmed by cleavage of caspase 3 and PARP as well as down-regulation of the MCL-1 and BCL-2 proteins. Moreover, ROR1 was dephosphorylated by KAN0441571C. Downstream of ROR1 both the Wnt canonical and non-canonical pathways were inactivated depending on the cell line. KAN0441571C had in most cell lines a similar cytotoxic effect as ibrutinib, acalabrutinib and venetoclax while bendamustine was inferior. KAN0441571C had an additive effect to ibrutinib, acalabrutinib and venetoclax respectively and KAN0441571C in combination with either of these three agents induced a complete killing of the cell lines. Conclusions: KAN0441571C is a second generation of a novel class of ROR1-tyrosine kinase inhibitor. This small molecule was effective in inducing apoptosis of MCL cells with other mechanisms of action than for drugs in clinical use for MCL. Combination of KAN0441571C with other MCL targeting drugs induced a complete killing of the tumor cell population in a preclinical in vitro model. Our results support the further development of ROR1 small molecule inhibitors as a new therapeutic principle in MCL as well as in other B-cell malignancies with an additive effect to existing targeted therapeutics. Disclosures Schultz: Kancera AB: Employment, Equity Ownership. Norin:Kancera AB: Employment. Olin:Kancera AB: Employment, Equity Ownership. Österborg:Janssen: Research Funding; Kancera AB: Research Funding; BeiGene: Research Funding; Abbvie: Research Funding; Gilead: Research Funding.

Key Points S1PR1 mutations are present in 7.8% of patients with MCL and are significantly more frequent at relapse. S1PR1 mutations reduce expression of the S1PR1 receptor, which mediates migration towards the tissue-to-blood egress factor S1P in MCL.

The cannabinoid receptors are upregulated in many types of cancers, including mantle cell lymphoma (MCL) and have been suggested to constitute novel therapeutic targets. The expression pattern of the key members of the endocannabinoid system was analyzed in a well-characterized MCL patient cohort and correlated to biological features. 107 tumor tissues were analyzed for the mRNA levels of cannabinoid receptors 1 and 2 (CNR1 and CNR2) and the two main enzymes regulating the endocannabinoid anandamide levels in tissue: NAPEPLD and FAAH (participating in synthesis and degradation, respectively). NAPEPLD, CNR1 and CNR2 were overexpressed while FAAH expression was reduced in MCL compared to non-malignant B-cells. Both low CNR1 and high FAAH levels correlated with lymphocytosis (p=0.016 and p=0.022, respectively) and with leukocytosis (p=0.0018 and p=0.047). Weak to moderate CNR1 levels were a feature of SOX11 negative MCL (p=0.006). Both high CNR2 and high FAAH levels correlated to anemia (p=0.0006 and p=0.038, respectively). In conclusion, the relative expression of the anandamide synthesizing and metabolizing enzymes in MCL is heavily perturbed. This finding, together with high expression of cannabinoid receptors, could favor enhanced anandamide signaling and suggest that targeting the endocannabinoid system might be considered as part of lymphoma therapy.

Sex determining region Y-box 11 (SOX11) expression is specific for mantle cell lymphoma (MCL) as compared with other non-Hodgkin's lymphomas. However, the function and direct-binding targets of SOX11 in MCL are largely unknown. We used high-resolution chromatin immunoprecipitation sequencing to identify the direct target genes of SOX11 in a genome-wide, unbiased manner and elucidate its functional significance. Pathway analysis identified WNT, PKA and TGF-beta signaling pathways as significantly enriched by SOX11-target genes. Quantitative chromatin immunoprecipitation sequencing and promoter reporter assays confirmed that SOX11 directly binds to individual genes and modulates their transcription activities in these pathways in MCL. Functional studies using RNA interference demonstrate that SOX11 directly regulates WNT in MCL. We analyzed SOX11 expression in three independent well-annotated tissue microarrays from the University of Wisconsin (UW), Karolinska Institute and British Columbia Cancer Agency. Our findings suggest that high SOX11 expression is associated with improved survival in a subset of MCL patients, particularly those treated with intensive chemotherapy. Transcriptional regulation of WNT and other biological pathways affected by SOX11-target genes may help explain the impact of SOX11 expression on patient outcomes.

Most lymphomas show an increased incidence and poorer prognosis in males vs females, suggesting endocrine regulation. We have previously shown that tumor growth in vivo of a murine T-cell-derived lymphoma is repressed following activation of estrogen receptor β (ERβ, ESR2). By using ERβ-deficient mice, we now demonstrate that this inhibition is mediated via a direct effect on the tumor cells and not on the microenvironment. Furthermore, we show that the growth-suppressing effects of ERβ agonist are also valid for human B-cell lymphomas as demonstrated in tumors derived from Granta-519 mantle cell lymphoma (MCL) and Raji Burkitt lymphoma (BL) cells. In Granta-519 MCL tumors, activation of ERβ reduced expression of BAFF and GRB7, 2 important molecules involved in B-cell proliferation and survival. Importantly, activation of ERβ inhibited angiogenesis and lymphangiogenesis, possibly mediated by impaired vascular endothelial growth factor C expression. Furthermore, using disseminating Raji BL cells, we show that ERβ activation reduces dissemination of grafted Raji BL tumors. We also show by immunohistochemistry that ERβ is expressed in primary MCL tissue. These results suggest that targeting ERβ with agonists may be valuable in the treatment of some lymphomas, affecting several aspects of the malignant process, including proliferation, vascularization, and dissemination.

The chromatin modifier EZH2 is overexpressed and associated with inferior outcome in mantle cell lymphoma (MCL). Recently, we demonstrated preferential DNA methylation of HOX genes in MCL compared with chronic lymphocytic leukemia (CLL), despite these genes not being expressed in either entity. Since EZH2 has been shown to regulate HOX gene expression, to gain further insight into its possible role in differential silencing of HOX genes in MCL vs. CLL, we performed detailed epigenetic characterization using representative cell lines and primary samples. We observed significant overexpression of EZH2 in MCL vs. CLL. Chromatin immune precipitation (ChIP) assays revealed that EZH2 catalyzed repressive H3 lysine 27 trimethylation (H3K27me3), which was sufficient to silence HOX genes in CLL, whereas in MCL H3K27me3 is accompanied by DNA methylation for a more stable repression. More importantly, hypermethylation of the HOX genes in MCL resulted from EZH2 overexpression and subsequent recruitment of the DNA methylation machinery onto HOX gene promoters. The importance of EZH2 upregulation in this process was further underscored by siRNA transfection and EZH2 inhibitor experiments. Altogether, these observations implicate EZH2 in the long-term silencing of HOX genes in MCL, and allude to its potential as a therapeutic target with clinical impact.

Introduction Mantle cell lymphoma (MCL) is an incurable disease with a median survival of 3-5 years. Most cases express SOX11, a transcription factor associated with MCL pathobiology, which serves as a diagnostic marker. Current standard first-line therapy for younger MCL patients is rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) and cytarabine (Ara-C), consolidated with high dose chemotherapy with autologous stem cell transplantation (ASCT), which is associated with prolonged survival (Eskelund et al. Br J Haematol 2016). Ara-C metabolizes into its active triphosphate form Ara-CTP which inhibits proliferation of the malignant cells. Recent reports suggest that the expression of the mammalian dNTPs hydrolase SAMHD1 determines response to Ara-C in acute myeloid leukemia (AML) by hydrolyzing Ara-CTP and thus by diminishing the anti-proliferative properties of Ara-C. Consequently, in vitro downregulation of SAMHD1 resulted in sensitization of AML cells to Ara-C (Herold et al., Nat Med 2017). SAMHD1 also exhibits anti-tumor properties via regulation of dNTP pool and is recurrently mutated in CLL (Clifford et al. Blood 2014) and T-PLL (Johansson et al. Blood Cancer J. 2018). In CLL a role in DNA-repair has been suggested (Clifford et al. Blood 2014). Thus, SAMHD1 may function as a tumor suppressor. In this study, we investigated for the first time the expression patterns of SAMHD1 in MCL and its association to clinical outcome, especially in patients receiving Ara-C as part of induction for ASCT. Methods SAMHD1 and SOX11 expression was investigated by qPCR, WB and IHC on whole tissue sections or tissue microarrays. MCL cell lines were treated with gene-specific siRNA for SAMHD1 or SOX11. Data on overall survival (OS) was retrieved from patient records. For patients included in the Nordic MCL2 and MCL3 trials data on progression free survival (PFS) and OS were retrieved. Results Initial IHC showed that expression of SAMHD1 is high in normal T-cells and macrophages and low in cells in the mantle zones of reactive tonsils. Co-staining with CD20 in a heterogeneously treated cohort of primary MCL (n=104) showed a large variation between cases (median 73.15%, range: 0.4%-99.6%) and the staining intensity was lower than in T-cells. Sixty two/104 samples were also evaluated for SOX11 expression and the percentage of SOX11 positive cells moderately correlated with SAMHD1 expression (Spearman correlation coefficient 0.27, p=0.036). Analysis of mRNA expression (normalized to mRNA levels of respective genes in Granta519 cell line) of SAMHD1 (median RFI: 2.09, range: 0.18-10.69) and SOX11 (median RFI: 2.00, range: 0.00-7.11) in flow cytometry sorted primary MCL cells (n=19) showed a trend for correlation (Spearman correlation coefficient 0.45, p=0.053). However, downregulation of SOX11 by siRNA did not alter the expression of SAMHD1 and neither did downregulation of SAMHD1 by siRNA change the expression of SOX11 suggesting that the observed correlation is not due to a mutual regulation. We investigated the relation of SAMHD1 expression to clinical and pathological parameters in this cohort and found no correlation to OS, blastoid morphology, proliferation (% Ki67+ tumor cells) nor p53 positivity (>20% positively stained cells). Further, a cohort of patients treated within the Nordic MCL2 and MCL3 protocols (n=51) were investigated for SAMHD1 expression by IHC. Interestingly the distribution of SAMHD1 expression was different in this cohort (median 34.9%, range: 2.2%-97.1%; Mann-Whitney p=0.0019). Survival analysis showed a trend for better PFS and OS in patients with high (>75% SAMHD1 positive cells) and low ( Conclusions In MCL the expression of SAMHD1 varies over a broad range and correlates to expression of SOX11. However, no significant difference in PFS or OS among patients receiving Ara-C containing induction chemotherapy is found in this study. Disclosures No relevant conflicts of interest to declare.

Introduction: The SAM domain and HD domain 1 (SAMHD1) protein is a deoxynucleoside triphosphate (dNTP) triphosphohydrolase, which has been initially described to restrict human immunodeficiency virus type 1 (HIV-1) in certain cell types through depletion of intracellular dNTP substrates required for HIV-1 reverse transcription. Mutations of SAMHD1 gene have been linked to Aicardi-Goutières syndrome (AGS) and have been identified as putative drivers of chronic lymphocytic leukemia resulting in decreased SAMHD1 mRNA and protein levels. More recently, SAMHD1 mutations have been reported in T-prolymphocytic leukemia (T-PLL). Based on these findings and the fact that SAMHD1 limits the dNTP pool in the cell, it may play a role in oncogenesis as a tumor suppressor. In addition, SAMHD1 may confer resistance to nucleoside-based chemotherapies by hydrolysing their active triphosphate metabolites, with cytarabine in acute myeloid leukemia being an example (Herold et al, Nat Med 2017; 23(2):256-263). The expression patterns and the potential role of SAMHD1 in the pathogenesis of peripheral T-cell lymphomas (PTCL) are not yet known. Methods: The patient cohort included 64 PTCLs of various histologic types which were diagnosed and treated at Karolinska University Hospital (Sweden). A control group of 4 reactive lymph nodes and 2 reactive tonsils was included in the study for comparison. All tissue samples were obtained prior to therapy. SAMHD1 expression was assessed by immunohistochemistry performed on a PTCL tissue microarray (TMA) with duplicate tumor cores from each case or full tissue sections using dual immunostaining (SAMHD1 / CD68) and a monoclonal antibody against SAMHD1 (Bethyl Laboratories, San Antonio, TX). At least 500 lymphoma cells were counted to calculate the percentage of SAMHD1-positive tumor cells. Overall survival (OS) was defined as time from diagnosis to death or last follow-up. Event-free survival (EFS) was defined as time from diagnosis to relapse, death, or last follow-up. Survival analyses were performed using the Kaplan-Meier method (log-rank test) and Cox regression models. Two T-cell lymphomas cell lines (Mac1, Mac2A) were used as an in vitro system. As our preliminary findings from in silico analysis revealed potential binding sites for MYC on the SAMHD1 gene promoter, we hypothesized that MYC might regulate SAMHD1 expression. Therefore, the T-cell lymphoma cell lines were treated with the selective BET / MYC inhibitor JQ-1 or transiently transfected with a MYC-overexpressing plasmid or MYC gene-specific siRNA constructs, respectively. Western blot analysis was used to assess the protein levels. Results: SAMHD1 protein was expressed in reactive T-cells and histiocytes (CD68+) in all reactive lymphoid tissues (lymph nodes and tonsils) with strong staining intensity. SAMHD was differentially expressed among PTCL subtypes generally with weaker staining intensity as compared to normal T-cells and histiocytes, thus being positive in all (100%) angioimmunoblastic T-cell lymphomas (AILT), 67% PTCL-NOS, 45% ALK+ ALCL, 20% of ALK+ ALCL, and none (0%) of T-lymphoblastic lymphomas (p=0.0017, chi-square test). Among the SAMHD1- positive cases, the percentage of positive lymphoma cells ranged from 0 to 100% and its highest median was observed in AILT. SAMHD1 expression inversely correlated with CD30 expression (% CD30+ positive lymphoma cells) (p=0.0025, Mann-Whitney test). No significant associations between SAMHD1 levels and other clinicopathologic parameters or clinical outcome (EFS or OS) were found, however, the number of patients analyzed in each histologic subtype was limited. Inhibition of MYC activity by JQ-1 or MYC gene silencing with specific siRNA resulted in a substantial increase in the SAMHD1 protein level in T-cell lymphoma cell lines. Inversely, transient transfection of the cell lines with a MYC overexpressing plasmid resulted in decreased levels of SAMHD1. Taken together, the in vitro data suggest a possible MYC-associated regulation (repression) of SAMHD1 gene expression in T-cell lymphoma. Conclusions: SAMHD1 is shown for the first time to be differentially expressed among PTCL types and its regulation may involve MYC. Preliminary survival analysis shows no significant associations of SAMHD1 expression with EFS and OS in this cohort of PTCL, however, analysis of a larger PTCL study group is underway to draw definite conclusions. Disclosures Österborg: Gilead: Consultancy, Research Funding; Beigene: Research Funding; Pharmacyclics: Research Funding; Janssen: Research Funding; Abbvie: Research Funding.

A common treatment for follicular lymphoma is rituximab monotherapy. To identify patients for whom this regimen is adequate as first-line therapy, we applied the World Health Organization (WHO) classification for grading follicular lymphoma in a prospective central pathology review of the biopsies of previously untreated patients in two randomized trials of rituximab without chemotherapy. In the first trial (n₁ = 53), higher WHO grades correlated with longer time to next treatment, independently of clinical prognostic factors (p = 0.030); the finding was replicated in the second trial (n₂ = 221; p = 0.019). Higher grades were associated with better treatment responses (p = 0.018). Furthermore, also grades externally confirmed by independent local pathologists correlated with time to next treatment (p = 0.048). Flow cytometry in a separate patient series showed that the intensity of CD20 increased with the malignant cell size (p0.00005). In conclusion, WHO grade 1 follicular lymphoma correlates with inferior outcome after rituximab monotherapy. WHO grading might provide a clinically useful tool for personalized therapy.

The immunomodulatory drug lenalidomide induces cytogenetic remissions in 75% of patients with myelodysplastic syndrome (MDS) and del(5)(q31) through unknown mechanisms. We investigated the in vitro effects of lenalidomide on growth and maturation in differentiating erythroblasts from MDS patients with del(5)(q31) (n=13) and from healthy controls (n=10). Lenalidomide selectively inhibited growth of del(5q) erythroblasts, while not affecting normal cells, including cytogenetically normal cells from MDS del(5q) patients. The inhibitory effect was more pronounced in erythroid than in myeloid cells. In order to gain insight into the mode of action of lenalidomide and to identify the molecular targets of this drug, we have investigated the gene expression profiles of the lenalidomide-treated and untreated intermediate erythroblasts from MDS del(5q) patients (n=9) and from healthy controls (n=8). GeneChip Human Genome U133 Plus 2.0 arrays (Affymetrix), covering over 47,000 transcripts representing 39,000 human genes, were used. Treatment with lenalidomide significantly influenced the pattern of gene expression in del(5q) intermediate erythroblasts, with up-regulation of VSIG4, PPIC, TPBG, and SPARC in all samples, and down-regulation of many genes involved in erythropoiesis, including HBA2, GYPA, and KLF1, in most samples. Up-regulation of SPARC (median 4.4-fold, range 2.4–9.5) is of particular interest since SPARC, a gene with known tumor suppressor functions, is both anti-proliferative and anti-angiogenic, and is located at 5q31–q32, within the commonly deleted region in MDS 5q- syndrome. Activin A was one of the most significant differentially expressed genes between lenalidomide-treated cells of MDS del(5q) patients and healthy controls. Activin A is a member of the transforming growth factor-beta superfamily, with pleiotropic functions including apoptosis of hemopoietic cells. We conclude that lenalidomide specifically inhibits growth of del(5q) erythroid progenitors, while not affecting cytogenetically normal cells. These novel findings suggest that up-regulation of SPARC and Activin A may underlie the potent effects of lenalidomide, in particular growth inhibition and anti-angiogenesis, in MDS with del(5)(q31). The localization of the SPARC gene to the CDR of the 5q- syndrome is intriguing and, in relation to the findings of the present study, we suggest that SPARC may well play a role in the molecular pathogenesis of the 5q- syndrome.

Downregulation of miR26A1 has been reported in various B-cell malignancies; however, the mechanism behind its deregulation remains largely unknown. We investigated miR26A1 methylation and expression levels in a well-characterized series of chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). From 450K methylation arrays, we first observed miR26A1 (cg26054057) as uniformly hypermethylated in MCL (n = 24) (all >75%), while CLL (n = 18) showed differential methylation between prognostic subgroups. Extended analysis using pyrosequencing confirmed our findings and real-time quantitative PCR verified low miR26A1 expression in both CLL (n = 70) and MCL (n = 38) compared to normal B-cells. Notably, the level of miR26A1 methylation predicted outcome in CLL, with higher levels seen in poor-prognostic, IGHV-unmutated CLL. Since EZH2 was recently reported as a target for miR26A1, we analyzed the expression levels of both miR26A1 and EZH2 in primary CLL samples and observed an inverse correlation. By overexpression of miR26A1 in CLL and MCL cell lines, reduced EZH2 protein levels were observed using both Western blot and flow cytometry. In contrast, methyl-inhibitor treatment led to upregulated miR26A1 expression with a parallel decrease of EZH2 expression. Finally, increased levels of apoptosis were observed in miR26A1-overexpressing cell lines, further underscoring the functional relevance of miR26A1. In summary, we propose that epigenetic silencing of miR26A1 is required for the maintenance of increased levels of EZH2, which in turn translate into a worse outcome, as shown in CLL, highlighting miR26A1 as a tumor suppressor miRNA.

Mantle cell lymphoma (MCL) is a heterogeneous disease with most patients following an aggressive clinical course, whereas others having an indolent behavior. We conducted an integrative and multidisciplinary analysis of 177 MCL to determine whether the immunogenetic features of the clonotypic B-cell receptors (BcR) may identify different subsets of tumors. Truly unmutated (100% identity) IGHV genes were found in 24% cases, 40% were minimally/borderline mutated (99.9%–97%), 19% significantly mutated (96.9%–95%), and 17% hypermutated (

Systemic mastocytosis (SM) may be associated with a clonal hematopoietic non-mast cell-lineage disease (AHNMD). SM and AHNMD even may be clonally related. This report contributes to a better understanding of the different morphological aspects of SM by demonstrating that various AHNMDs can be detected in one patient during the course of disease. Routinely processed biopsy specimens of bone marrow and spleen removed from a 63-year-old man were investigated including a broad panel of immunohistochemical stainings. KIT codon 816 mutation analysis was carried out by melting point analysis of nested PCR products amplified from DNA of pooled microdissected mast cells. The histomorphological features of the initial bone marrow showed diffuse infiltration by hairy cell leukemia (HCL). Occult SM was only detected retrospectively by demonstration of a slight diffuse increase in loosely scattered, spindle-shaped mast cells carrying the activating point mutation KIT ( D816V ). In the second bone marrow, core biopsy removed about two years later HCL had been completely eradicated, while a diagnosis of SM-AHNMD with multifocal compact mast cell infiltrates associated with a myeloproliferative neoplasm (MPN) and significant increase in eosinophilic granulocytes was established. The third and last bone marrow biopsy specimen lacked the features of both MPN and HCL but showed progression into a secondary mast cell leukemia (MCL) with a focal sarcomatous component. To the best of the authors' knowledge, this is the first description of a case of SM-AHNMD with coexisting hematological neoplasms of lymphatic and myeloid origin initially presenting as occult disease and terminating as secondary MCL.

Mantle cell lymphoma (MCL) and chronic lymphocytic leukemia (CLL) both belong to the group of mature B-cell malignancies. However, MCL is typically clinically aggressive while the clinical course of CLL varies. CLL can be divided into prognostic subgroups based on IGHV mutational status and into multiple subsets based on closely homologous (stereotyped) B-cell receptors. In paper I we investigated 31 MCL cases using high-density 250K single-nucleotide polymorphism arrays and gene expression arrays. Although most copy-number aberrations (CNAs) were previously reported in MCL, a novel deletion was identified at 20q (16%) containing the candidate tumor suppressor gene ZFP64. A high proliferation gene expression signature was associated with poor prognosis, large CNAs, 7p gains and 9q losses. Losses at 1p/8p/13q/17p were associated with increased genomic complexity. In paper II we sequenced exons 4 to 8 of the TP53 gene in 119 MCL cases. 17p copy-number status was known from previous studies or determined by real-time quantitative polymerase chain reaction. TP53 mutations were detected in 14% of cases and were strongly associated with poor survival while 17p deletions were more common (32%) but did not predict survival. In papers III and IV we applied high-resolution genomic 27K methylation arrays to 20 MCL and 39 CLL samples. In paper III MCL displayed a homogenous methylation profile without correlation with the proliferation signature whereas MCL was clearly separated from CLL. Gene ontology analysis revealed enrichment of developmental genes, in particular homeobox transcription factor genes, among targets methylated in MCL. In paper IV we compared three different stereotyped CLL subsets: #1 (IGHV unmutated), #2 (IGHV3-21) and #4 (IGHV mutated). Many genes were differentially methylated between each two subsets and immune response genes (e.g. CD80 and CD86) were enriched among genes methylated in subset #1 but not in subsets #2/#4. In summary, CNAs were frequent and not random in MCL. Specific CNAs correlated with a high proliferation gene expression signature or genomic complexity. TP53 mutations predicted short survival whereas 17p deletions did not. A high proliferation signature was not associated with differential DNA methylation in MCL, which demonstrated a homogeneous methylation pattern. In contrast, genomic methylation patterns differed between MCL and CLL and between stereotyped CLL subsets.

Purpose: T cells influence outcome in follicular lymphoma, but their contributions seem to be modified by therapy. Their impact in patients receiving rituximab without chemotherapy is unknown. Experimental Design: Using flow cytometry, we evaluated the T cells in tumors and/or blood in a total of 250 follicular lymphoma patients included in two Nordic Lymphoma Group randomized trials that compared single rituximab with IFN-α2a–rituximab combinations. Results: In univariate analysis, higher levels of CD3+, CD4+, and CD8+ T cells in both tumors and blood correlated with superior treatment responses, and in multivariate analysis, tumor-CD3+ (P = 0.011) and blood-CD4+ (P = 0.029) cells were independent. CD4+ cells were favorable regardless of treatment arm, but CD8+ cells were favorable only in patients treated with single rituximab, because IFN-α2a improved responses especially in patients with low CD8+ cell levels. Higher levels of blood-CD3+ (P = 0.003) and blood-CD4+ (P = 0.046) cells predicted longer overall survival, and higher levels of blood-CD8+ cells longer times to next treatment (P = 0.046). Conclusions: We conclude that therapeutic effects of rituximab are augmented by tumor-associated T cells for rapid responses and by systemic T cells for sustained responses. CD4+ and CD8+ cells are both favorable in patients treated with rituximab. IFN-α2a abrogates the negative impact of few CD8+ cells. Clin Cancer Res; 17(12); 4136–44. ©2011 AACR.

Mantle cell lymphoma (MCL) is characterized by the t(11;14)(q13;q32) and numerous copy number aberrations (CNAs). Recently, gene expression profiling defined a proliferation gene expression signature in MCL where high scores predict shorter survival. We investigated 31 MCL cases using high-density single nucleotide polymorphism arrays and correlated CNA patterns with the proliferation signature and with clinical data. Many recurrent CNAs typical of MCL were detected, including losses at 1p (55%), 8p (29%), 9q (29%), 11q (55%), 13q (42%) and 17p (32%), and gains at 3q (39%), 8q (26%), 15q (23%) and 18q (23%). A novel deleted region at 20q (16%) contained only one candidate gene, ZFP64, a putative tumor suppressor. Unsupervised clustering identified subgroups with different patterns of CNAs, including a subset (19%) characterized by the presence of 11q loss in all cases and by the absence of 13q loss, and 3q and 7p gains. Losses at 1p, 8p, 13q and 17p were associated with increased genomic complexity. High proliferation signature scores correlated with increased number of large (>15 Mbp) CNAs (P = 0.03) as well as copy number gains at 7p (P = 0.02) and losses at 9q (P = 0.04). Furthermore, large/complex 13q losses were associated with improved survival (P < 0.05) as were losses/copy number neutral LOH at 19p13 (P = 0.01). In summary, this high-resolution genomic analysis identified novel aberrations and revealed that several CNAs correlated with genomic complexity, the proliferation status and survival.

Purpose: The microenvironment influences outcome in follicular lymphoma. Our hypothesis was that several immune cell subsets are important for disease outcome and their individual prognostic importance should be demonstrable in the same analysis and in competition with clinical factors. Experimental Design: Seventy follicular lymphoma patients with extreme clinical outcome (“poor” and “good” cases) were selected in a population-based cohort of 197. None of the 37 good-outcome patients died from lymphoma, whereas all the 33 poor-outcome patients succumbed in ≤5 years. Furthermore, the good-outcome patients were followed for a long time and needed no or little treatment. A tissue microarray was constructed from diagnostic, pretreatment biopsies. Cellular subsets were quantified after immunostaining, using computerized image analysis, separating cells inside and outside the follicles (follicular and interfollicular compartments). Flow cytometry data from the same samples were also used. Results: Independently of the Follicular Lymphoma International Prognostic Index, CD4+ cells were associated with poor outcome and programmed death-1–positive and CD8+ cells were associated with good outcome. The prognostic values of CD4+ and programmed death-1–positive cells were accentuated when they were follicular and that of CD8+ cells were accentuated when they were interfollicular. Follicular FOXP3+ cells were associated with good outcome and interfollicular CD68+ cells were associated with poor outcome. Additionally, high CD4/CD8 and CD4 follicular/interfollicular ratios correlated with poor outcome. Conclusion: There are many important immune cell subsets in the microenvironment of follicular lymphoma. Each of these is independently associated with outcome. This is the first study showing the effect of the balance of the entire microenvironment, not only of individual subsets. Clin Cancer Res; 16(2); 637–50.

PurposeThe results of immunohistochemical class prediction and prognostic stratification of diffuse large B-cell lymphoma (DLBCL) have been remarkably various thus far. Apart from biologic variations, this may be caused by differences in laboratory techniques, scoring definitions, and inter- and intraobserver variations. In this study, an international collaboration of clinical lymphoma research groups from Europe, United States, and Canada concentrated on validation and standardization of immunohistochemistry of the currently potentially interesting prognostic markers in DLBCL.Patients and MethodsSections of a tissue microarray from 36 patients with DLBCL were stained in eight laboratories with antibodies to CD20, CD5, bcl-2, bcl-6, CD10, HLA-DR, MUM1, and MIB-1 according to local methods. The study was performed in two rounds firstly focused on the evaluation of laboratory staining variation and secondly on the scoring variation.ResultsDifferent laboratory staining techniques resulted in unexpectedly highly variable results and very poor reproducibility in scoring for almost all markers. No single laboratory stood out as uniformly poor or excellent. With elimination of variation due to staining, high agreement was found for CD20, HLA-DR, and CD10. Poor agreement was found for bcl-6 and Ki-67. Optimization of techniques and uniformly agreed on scoring criteria improved reproducibility.ConclusionThis study shows that semiquantitative immunohistochemistry for subclassification of DLBCL is feasible and reproducible, but exhibits varying rates of concordance for different markers. These findings may explain the wide variation of biomarker prognostic impact reported in the literature. Harmonization of techniques and centralized consensus review appears mandatory when using immunohistochemical biomarkers for treatment stratification.

PTEN and SHP1 are tumor suppressor genes involved in the regulation of cell cycle control and apoptosis. The authors investigated the protein expression of PTEN and SHP1, by immunohistochemistry in tissue microarrays from bone marrow samples in children, diagnosed with acute lymphoblastic leukaemia and nonmalignant controls. PTEN was overexpressed in diagnostic ALL samples, while SHP1 showed a low expression. Both proteins showed a significant difference in expression compared to nonmalignant controls. The roles of PTEN and SHP1 are not well investigated in pediatric leukemia and could in the future play a role as prognostic factors.

Summary Gene expression analysis demonstrated high expression of the neuronal transcription factor SOX11 in mantle cell lymphoma (MCL). In contrast to follicular lymphoma, small lymphocytic lymphoma and reactive lymphoid tissue, most MCLs tested (48/53 patients) expressed sox11 protein in the nucleus. Therefore nuclear sox11 expression represents a new tumour marker for a subset of MCL. However, 5/53 MCL cases expressed sox11 only in the cytoplasm; these MCL patients had a shorter survival compared to MCL with nuclear sox11 expression. These results suggest sox11 expression as a new diagnostic marker in MCL that could be related to the clinical and biological behaviour of MCL.

Purpose: Follicular lymphoma is a heterogeneous disease with variable prognosis and clinical course. We hypothesized that the presence of nonmalignant T cells in the microenvironment of the tumor may affect the outcome.Experimental Design: Using flow cytometry, we evaluated the T-cell subsets in the lymph node microenvironment of follicular lymphoma. All patients in South Stockholm County with indolent follicular lymphoma and with flow cytometry done on a diagnostic lymph node between 1994 and 2004 were included (N = 139). Diagnosis and grade (1, 2, and 3a) were confirmed by re-review. Flow cytometry results were reanalyzed. Lymphocyte subsets, the Follicular Lymphoma International Prognostic Index, grade, and clinical characteristics were evaluated in univariable and multivariable Cox analysis with respect to overall survival (OS) and disease-specific survival (DSS).Results: Higher CD8+ T-cell levels correlated with longer OS and DSS, independently of the Follicular Lymphoma International Prognostic Index (OS, P = 0.017; DSS, P = 0.020) and independently of all other prognostic factors (OS, P = 0.001; DSS, P = 0.004). Median OS was not reached for patients in the upper quarter of CD8+ T-cell levels (>8.6%), 10.4 years for patients in the middle half (4.2-8.6%), and 6.0 years for patients in the lower quarter (Conclusions: Higher levels of CD8+ T cells predict a better prognosis, and these data support an important role for nonmalignant immune cells in the biology of follicular lymphoma. Evaluating the CD8+ T cells by flow cytometry at diagnosis may provide prognostic information.

Mantle cell lymphoma is a clinically heterogeneous disease, where further elucidation of pathogenetic mechanisms and better prognostic information is required. We evaluated genetic aberrations by interphase FISH on tissue sections or cytological material in 38 samples from 30 MCL patients, including 5 cases with cyclin D1 3'UTR low, which previously has been associated to unfavourable prognosis. The findings have been related to proliferation and clinical outcome. All but one of MCL showed t(11:14) translocation and in 22/30 samples taken at diagnosis or first relapse, one or several cytogenetic changes were detected; 11 deletions of ATM, 13 p53 deletions, 8 numerical c-myc-aberrations and 6 delp16. All but one MCL with low cyclin D1 3'UTR had additional cytogenetic changes, however no particular genetic change was strictly associated with this MCL variant. One fourth of MCL had none of the investigated additional aberrations and these tumours were in general less proliferative and some of these patients had a very long survival.

The cannabinoid receptor type 1 (CB1) antagonist rimonabant has been used as treatment for obesity. In addition, anti-proliferative effects on mitogen-activated leukocytes have been demonstrated in vitro. We have previously shown that rimonabant (SR141716A) induces cell death in ex vivo isolated malignant lymphomas with high expression of CB1 receptors. Since CB1 targeting may be part of a future lymphoma therapy, it was of interest to investigate possible effects on peripheral blood mononuclear cells (PBMC) in patients treated with rimonabant. We therefore evaluated leukocyte subsets by 6 color flow cytometry in eight patients before and at treatment with rimonabant for 4 weeks. Whole-transcript gene expression profiling in PBMC before and at 4 weeks of rimonabant treatment was done using Affymetrix Human Gene 1.0 ST Arrays. Our data show no significant changes of monocytes, B cells, total T cells or T cell subsets in PBMC during treatment with rimonabant. There was a small but significant increase in CD3–, CD16+ and/or CD56+ cells after rimonabant therapy. Gene expression analysis detected significant changes in expression of genes associated with innate immunity, cell death and metabolism. The present study shows that normal monocytes and leukocyte subsets in blood remain rather constant during rimonabant treatment. This is in contrast to the induction of cell death previously observed in CB1 expressing lymphoma cells in response to treatment with rimonabant in vitro. These differential effects observed on normal and malignant lymphoid cells warrant investigation of CB1 targeting as a potential lymphoma treatment.

We have earlier reported overexpression of the central and peripheral cannabinoid receptors CB1 and CB2 in mantle cell lymphoma (MCL), a B cell non-Hodgkin lymphoma. In this study, treatment with cannabinoid receptor ligands caused a decrease in viability of MCL cells, while control cells lacking CB1 were not affected. Interestingly, equipotent doses of the CB1 antagonist SR141716A and the CB1/CB2 agonist anandamide inflicted additive negative effects on viability. Moreover, treatment with the CB1/CB2 agonist Win-55,212-2 caused a decrease in long-term growth of MCL cells in culture. Induction of apoptosis, as measured by FACS/Annexin V–FITC, contributed to the growth suppressive effect of Win-55,212-2. Our data suggest that cannabinoid receptors may be considered as potential therapeutic targets in MCL.

The role of transcript variants of cyclin D1 in cancer biology is unclear. Most tumors with high levels of cyclin D1 express 2 transcripts due to alternative splicing: one full-length transcript of 4.4 kb and one short transcript of approximately 1.7 kb. The short transcript lacks part of the 3 0 UTR region regulating mRNA stability and has a longer half-life. In our study, the contribution of each of these mRNAs to gene expression and cell proliferation has been investigated in mantle cell lymphoma (MCL), a B cell lymphoma characterized by a specific gene translocation resulting in enhanced expression of cyclin D1. A subset of MCL tumors with low levels of the long cyclin D1 transcript (cyclin D1 3 0 UTR) was identified by quantitative PCR and by oligonucleotide array hybridization. This tumor-subset had 3.4-fold higher levels of the short form of cyclin D1 mRNA (p < 0.0001) and had higher expression of cyclin D1 protein. Gene expression analysis identified a number of cell-cycle regulatory genes as upregulated. There was a significant difference in frequencies of cyclin B1 (p 5 0.0006) and cyclin A2 (p 5 0.0006) positive cells that discriminated MCL with low cyclin D1 3 0 UTR from other highly proliferative MCL. Among differentially expressed genes, there was a highly upregulated gene with homology to the group of cell-cycle promoting E2F transcription partners, E2F_TDP5. Several of the upregulated genes, such as TOP2A, AURORA A and RRM2 may influence a response to therapy. Identification of MCL with low cyclin D1 3 0 UTR is important because it seems to be associated with shorter overall survival. ' 2005 Wiley-Liss, Inc.

Early-onset melanoma under the age of 20 years is still a rare disease but has an increasing incidence. The aim of this study was to determine whether CDKN2A germline mutations are present in patients diagnosed with childhood/adolescent melanoma. From the Swedish Cancer Register we identified 60 patients with a diagnosis of cutaneous malignant melanoma before the age of 20 years. A medical history including information on self-reported melanoma heredity was obtained, a physical examination was performed by a dermatologist, and the histopathology slides were reviewed. A blood test was obtained for analysis of germline CDKN2A exon 1 and exon 2 mutations by DNA sequencing. We found only one germline CDKN2A mutation with functional significance, which was an exon 1 missense mutation resulting in a proline-to-leucine substitution in codon 48. This mutation was seen in a patient belonging to a previously reported kindred with hereditary melanoma where this particular germline CDKN2A mutation had been identified. Thus, in the large majority of cutaneous melanoma in childhood/adolescence, any underlying genetic alterations have yet to be identified.

Background: Posttransplant lymphoproliferative disease (PTLD) is a serious complication after organ transplantation associated with a high mortality, and is often caused by a primary or reactivated Epstein-Barr virus (EBV) infection. The incidence of PTLD ranges from 1% to 10%, depending on the type of organ transplanted and the immunosuppressive regimens used. Methods: In this retrospective study from a single center, 12 (2.4%) of 500 consecutive recipients of liver grafts developed lymphoma. Patient data were obtained by chart review. All diagnostic biopsies were reviewed by two hematopathologists. Results: The median time between transplantation and the diagnosis of lymphoma was 19.5 (1.5–148) mo. Nine of the patients had been treated with OKT-3 and/or ATG after the transplantation. Two patients had a pretransplant diagnosis of lymphoma. The PTLD was of high grade in all patients, and was associated with EBV in 6 of 9 examined cases. No relation with human herpesvirus-8 could be detected. In all patients, immuno-suppression was reduced at the time of lymphoma diagnosis. Chemotherapy was used in all patients, mostly upfront but in one patient after lymphoma progression after reduction of immunosuppression. Nine patients also got antiviral therapy. Immunotherapy with the monoclonal antibody rituximab was used in one patient. Half of the patients are alive, in complete continuous remission, more than 4 yr after the lymphoma diagnosis. Two patients died of neutropenic sepsis, three of persistent lymphoma, and one of recurrent cirrhosis while in complete remission. Conclusions: PTLD is a significant complication in liver-transplanted patients. Intensive chemotherapy can induce long-term remissions in a substantial number of patients. The role for monoclonal antibodies in this setting should be investigated further.

Mantle cell lymphoma (MCL) is a moderately aggressive B-cell lymphoma that responds poorly to currently used therapeutic protocols. In order to identify tumour characteristics that improve the understanding of biology of MCL, analysis of oligonucleotide microarrays were used to define specific gene expression profiles. Biopsy samples of MCL cases were compared to reactive lymphoid tissue. Among genes differentially expressed in MCL were genes that are involved in the regulation of proliferation, cell signalling, adhesion and homing. Furthermore, some genes with previously unknown function, such as C11orf32, C2orf10, TBC1D9 and ABCA6 were found to be differentially expressed in MCL compared to reactive lymphoid tissue. Of special interest was the high expression of the cannabinoid receptor 1 (CB1) gene in all MCL cases analysed. These results were further confirmed at the cellular and protein level by immunocytochemical staining and immunoblotting of MCL cells. Furthermore, there was a reduced expression of a regulator of G protein signalling, RGS13 in all MCLs, with a complete absence in the majority of cases while present in control lymphoid tissue. These results were further confirmed by PCR. Sequencing of the RGS13 gene revealed changes suggesting polymorphisms, indicating that downregulation of the expression of RGS13 is not related to mutations, but may serve as a new specific marker for MCL. Moreover, comparison between individual cases of MCL, revealed that the CCND1 gene appears to be differently expressed in MCL cases with high vs low proliferative activity.

Purpose: The purpose of this study was to investigate the impact of T-cell subsets on pathologic and clinical features including disease outcome in mantle cell lymphoma (MCL). Experimental Design: Cell populations were investigated using flow cytometry in diagnostic MCL (n = 153) and reactive (n = 26) lymph node biopsies. Levels of tumor cells, T cells, T-cell subsets, and the CD4:CD8 ratio were assessed and related to pathologic and clinical parameters. Results: MCL cases with diffuse and nodular histologic subtypes showed lower levels of T cells, especially CD4+ T cells, than those with mantle zone growth pattern. Both CD3 and CD4 levels were lower in the nodular subtype than in mantle zone (P = 0.007; P = 0.003) and in the diffuse compared with the nodular subtype (P = 0.022; P = 0.015). The CD4:CD8 ratios were inversely correlated to tumor cell proliferation (P = 0.003). Higher levels of CD3+ and CD4+ T cells and higher CD4:CD8 ratios were associated with indolent disease (P = 0.043, 0.021, and 0.003 respectively). In univariate analysis, a high CD4:CD8 ratio, but not the histologic subtype, was correlated to longer overall survival (OS). In multivariate analysis, the CD4:CD8 ratio correlated with OS independently of Mantle Cell Lymphoma International Prognostic Index (MIPI) and high p53 expression (P = 0.023). Conclusion: CD3+, CD8+, and particularly CD4+ T-cell levels are higher in indolent MCL and decrease with more aggressive histology as reflected by a diffuse growth pattern. High CD4:CD8 ratio correlated independently of other high-risk prognostic factors with longer OS, suggesting a prognostic role for T cells in MCL. Clin Cancer Res; 20(23); 6096–104. ©2014 AACR.

The differential diagnosis between mantle cell lymphoma (MCL) and B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (B-CLL/SLL) is essential, since MCL usually has a more aggressive clinical course. By flow cytometry both MCL and B-CLL are CD19, CD20 and usually CD5 positive. However, ambiguities in other immune phenotypic markers of these lymphoma entities sometimes complicate the flow cytometric differential diagnosis. We here demonstrate that the transcription factor SOX11, which is highly up-regulated in most MCL, can be analyzed by flow cytometry. SOX11 protein could be consistently detected in ex vivo isolated MCL but not in B-CLL/SLL. Flow cytometry also enabled protein quantification, and SOX11 protein levels correlated with mRNA expression. We suggest that implementing detection of SOX11 in diagnostic flow cytometry would be beneficial for accurate and reliable diagnosis of MCL, especially for distinguishing cases of MCL and B-CLL/SLL with aberrant immune phenotypes, and for cases of rare cyclin D1 negative MCL.

Alterations in the tumor suppressor gene TP53 have been associated with poor outcome in adult hematological malignancies. We have earlier reported an increased expression of the TP53 encoded protein p53, in bone marrow samples from pediatric patients with aggressive leukemia. Our aim was now to evaluate p53 protein expression at different time points before and after hematopoietic stem cell transplantation (HSCT) as a predictor of relapse in a group of children diagnosed with MDS, JMML and CML, and also investigate if potential alterations in expression could be correlated to mutations in TP53.Paraffin embedded bone marrow samples from 33 pediatric patients diagnosed with MDS, JMML and CML between 1997 and 2010 were collected retrospectively from time of diagnosis and pre and post HSCT. Immunohistochemistry (IHC) was performed on tissue microarrays (TMA) with antibodies to p53 and p21. DNA sequencing of exon 2-11 of TP53 was performed in 7 patients with JMML and 5 patients with MDS.Elevated p53 protein expression at diagnosis predicted for relapse, odds ratio (OR) 1.19 (95% CI: 1.02-1.40, p = .028). Sequencing of TP53 did not reveal any mutations in the 12 patients analyzed and p53 expression correlated positively to p21 expression indicating a functional p53/p21 protein pathway.Elevated p53 protein expression at diagnosis may be an indicator of relapse in children with MDS, JMML and CML.

Most patients with systemic mastocytosis (SM) carry a D816 V KIT mutation causing a ligand-independent activation of the receptor. Down-stream of KIT is several components known to be mutated in different malignancies. RAF is among the most frequently mutated kinases, where BRAF V600E mutation occurs in most hairy cell leukemias (HCL) and half of malignant melanomas. We investigated BRAF mutations in 36 subjects with different forms of SM, but could not detect BRAF mutation in any of the cases, not even in the mast cell lineage of a patient with V600E BRAF-positive HCL. Thus, although BRAF is commonly mutated it appears not to be present in SM.

Mantle cell lymphoma (MCL) is a B cell Non-Hodgkin lymphoma comprising approximately 8% of malignant lymphomas. MCL is considered to be an incurable disease even though survival has improved with novel biological therapies that interrupt survival signaling from the lymphoma microenvironment. The signaling pathways that are deregulated and the factors leading to systemic dissemination of the disease are still poorly understood. There is also a clear need to identify additional druggable targets for therapy (Saba and Wiestner, Curr Opin Hematol, 2014). Druggable targets may be G-protein coupled receptors (GPCRs) and G-proteins. GPCRs belong to the family of seven transmembrane receptors, which upon activation by extracellular ligands transfer the signals inside the cell for activation of the specific pathway. The signaling involves G-proteins. G-proteins consist of the subunits: alpha, beta and gamma and their subtypes. During GPCR activation the G alpha subunit is released and the subtype of G-protein subunit determines which downstream signaling pathways (including Akt, PI3K, ERK, JNK, MAPK, NFkappaB and others) is then activated. In the immune cells different subtypes of G-proteins alpha are instrumental for leukocyte migration, architecture of B cells compartments in spleen, thymus, lymph nodes, and gastrointestinal tract (Hwang et al., PlosOne, 2013) and BCR-mediated cell death (Misra et al., J Exp Med, 2010). G alpha13 signaling is involved in development of germinal centre-derived lymphomas (Muppidi et al., Nature, 2014). In order to map the aberrant expression of GPCR and G-proteins in MCL, the expression of genes encoding for GPCRs and G-protein alpha subunits was analyzed by Affymetrix U133A Array of seventeen MCL biopsies and eight non-malignant lymph nodes. Among investigated GPCR and G-protein alpha subunit genes 25/298 were differently expressed in MCL compared to reactive lymph nodes (moderated t-test, adj. p=or< than 0.05). The four most significantly different genes expressed were: LPAR6, GPRC5C, OPN3 and GNAZ (all adj.p Disclosures No relevant conflicts of interest to declare.

To assess whether there has been a change in histological features and prognostic factors of primary cutaneous malignant melanoma (CMM) in young individuals in Sweden, an unselected, population-based study was undertaken; 177 cases of primary CMM in persons below 20 years of age were reported to the Swedish National Cancer Registry between 1973 and 1992. In 87% of the cases, original tumor tissue was available for histo-pathological review. The original diagnosis was verified in 88% (n = 126) of these cases. All tumors had histological features similar to adult CMM; 17% had an associated precursor lesion. Superficial spreading melanoma (SSM) was the most common sub-type, constituting 20/36 cases in the first decade and 59/90 in the second. Corresponding figures for nodular melanoma (NM) were 11/36 and 23/90. Only 5 melanomas in situ were diagnosed. In girls, the mean thickness of SSM decreased from 1.5 to 0.6 mm (p0.001). Overall mortality was 10%, 22% in the group with CMM diagnosed 0-15 years of age and 8% in individuals 15-19 years. Fatal CMM cases diagnosed below 15 years of age (n = 4) were NM1.6 mm thick and in subjects 15-19 years (n = 9) 44% of fatal tumors were NM with a mean thickness of 2.2 mm. Breslow index was the single most important prognostic factor. However, when known prognostic factors were adjusted for in a Cox regression analysis, young age remained an independent risk factor, with a relative death rate of 0.21 for individuals aged 15-19 compared with children15 years of age.