ALBERT

Description: Abstract 3292 Previous studies have demonstrated that many T cell subsets possess NK-like features, including the CD56+ and KIR+ populations. Collectively, these studies showed that these NK-like T cells are predominantly αβ+ CD8+ with memory phenotype and could recognize HLA-E associated viral peptides after expansion upon TCR engagement. However, their clonality, transcriptome, regulation, specificity, and memory response in human have not been fully elucidated. We hypothesize that these NK-like T cells are phenotypically and functionally distinct from conventional T and NK cells and they play unique roles in virus and cancer control. Herein, we extensively characterized the CD56+ T cells and the KIR+ T subset by analysis of TREC, TCRVβ spectrum, telomere length, surface biomarkers, genome-wide transcriptome, multi-analyte cytokine profiling, cancer cell susceptibility, tetramer staining, and real-time response to CMV reactivation in stem cell transplant recipients. In contrast to CD56– T cells, CD56+ T cells are limited in TREC, TCRVβ, telomere length, cytokine secretion, transcription of metabolic genes stx6, nnt, galnt2, hvcn1, tyms, rpa1 tmf1, ecop, and tspan3, and are mostly KIR+, CD8+, DNAM1+, NKG2D+, CD44+, NKp46– and CD25–. Compared to KIR– CD56+ T cells, KIR+ CD56+ T cells are even more limited in TREC, TCRVβ, telomere length, and cytokine secretion, but have elevated transcription of NK cytotoxicity-related genes arrb1, ppp3cc, and lamc3, higher degranulation after activation by IL-2/IL-15 and CD3/CD28 antibodies, better killing of cancer cells after cytokine priming, and are mostly KIR2DL2/3+, NKG2D+, NKp46+, CD16+, NKG2C+, CD57+, and 2B4+. Importantly during CMV reactivation after stem cell transplantation, the percentage of KIR+ CD56+ T cells in the patient's blood increased dramatically and was significantly higher (p=0.0021) than in those without viral reactivation. Ex vivo, KIR+ CD56+ T cells demonstrate CMVpp65 tetramer staining, memory response to CMV peptides, and potent lysis of CMVpp65-pulsed target cells dependent on both KIR and TCR specificity. Furthermore, we identified for the first time that KIR– CD56+ T cells are Rorc+ IL-13-secretor. In conclusion, both CD56+ and KIR+ NK-like T-cell subsets are unique in biological and clinical properties and have distinct roles in cancer and infection control. Disclosures: No relevant conflicts of interest to declare.

Description: Background: Peripheral T-cell lymphoma (PTCL) consists of an uncommon and heterogeneous group of lymphomas that are often challenging to diagnose and classify. Since most patients also have a poor survival with standard multiagent chemotherapy, more effective therapeutic approaches are needed to improve patient outcome. Table1: Pathological diagnosis Number of cases profiled AITL 36 ALK(+)ALCL 19 ALK (−)ALCL 08 ATLL 12 T/NK 14 PTCLU 44 Other rare entities 10 Methods: A mRNA profiling study using Affymetrix HGU133+2 arrays on 143 cases of PTCL and NK-cell lymphoma (NKCL) from the International Peripheral T-cell Lymphoma Project, was conducted on pre-treatment biopsies. These included the following pathologically classified cases (Table 1). In addition, we also profiled nine NK cell lines, seven T cell lines, normal resting and activated CD4+ and CD8+ T cells and resting and IL2- activated NK cells from healthy individuals. BRB-ArrayTools was used to develop gene classifiers for the major PTCL entities and survival predictors for AITL based on gene expression data. Results: We have identified key molecular signatures for PTCL and NKCL that have allowed us to construct a robust classifier for AITL (207 transcripts), ALK+ ALCL (94), ATLL (225) and NKCL (127). PTCL-U group may have 3 or 4 molecular subgroups and additional studies with more cases, are necessary to further define this group. Misclassified cases were identified and re-assigned to the molecularly defined entities, including re-assigning of 9/44 PTCL-U to AITL. We have confirmed the enriched expression of genes identified in follicular helper T-cells in AITL, suggesting that AITL is derived from this T-cell subset. A number of oncogenic pathways (e.g. NF-κB, HIF-a,VEGF, IL6) and tumor/host interactions that contributed to local tumor-induced immunosuppression (e.g. TGF-b), were identified in AITL. A molecular predictor of outcome was developed for AITL and validated by leave one-out-cross validation. Since PTCL is an uncommon disease, future studies will require the collaboration of multiple large clinical groups with tissue resources for both discovery and validation. Conclusion: This study has demonstrated that GEP will allow the construction of robust and biologically-meaningful classifiers for PTCL, and prognosticators can be derived for well-defined entities with a sufficient number of cases. GEP will also allow us to identify therapeutically-relevant oncogenic pathways and tumor/host interactions that may lead to improvement in the therapy and outcome of patients with PTCL and NKCL. (This study is a part of the International T-cell Lymphoma Project)

Description: Peripheral T-cell lymphoma (PTCL) is often challenging to diagnose and classify. Gene expression profiling was performed on 144 cases of PTCL and natural killer cell lymphoma and robust molecular classifiers were constructed for angioimmunoblastic T-cell lymphoma (AITL), anaplastic lymphoma kinase-positive (ALK+) anaplastic large-cell lymphoma (ALCL), and adult T-cell leukemia/lymphoma. PTCL-unclassifiable was molecularly heterogeneous, but we were able to identify a molecular subgroup with features of cytotoxic T lymphocytes and a poor survival compared with the remaining PTCL–not otherwise specified cases. Many of the pathologic features and substantial components of the molecular signature of AITL are contributed by the follicular dendritic cells, B-cell, and other stromal components. The expression of Th17-associated molecules in ALK+ ALCL was noted and may represent aberrant activation of Th17-cell differentiation by abnormal cytokine secretion. Adult T-cell leukemia/lymphoma has a homogeneous molecular signature demonstrating high expression of human T-lymphotropic virus type 1–induced genes. These classifiers reflect the biology of the tumor cells as well as their microenvironment. We also constructed a molecular prognosticator for AITL that appears to be largely related to the microenvironmental signature, and the high expression of 2 immunosuppressive signatures are associated with poor outcome. Oncogenic pathways and tumor-host interactions also were identified, and these findings may lead to better therapies and outcome in the future.

Description: Background: Natural Killer (NK)-cell lymphomas/leukemias (NKL) account for 1–2 % of all non-Hodgkin lymphomas. Although the incidence of NKL is relatively low, the clinical course of these lymphomas is highly aggressive. To elucidate the recurrent genomic abnormalities and the associated changes in the gene expression profile, we performed GEP and array-CGH studies on seven clinically well defined cases and eight well characterized cell lines derived from NKL patients. Methods: Array-CGH was performed on a tiling BAC array and GEP on an Affymetrix 133 plus2 array. The two data sets were correlated to identify functional alterations associated with the genetic abnormalities. Candidate genes on del 6q21 were identified and further studied for mutations and promoter methylation. Results: Our aCGH study identified frequent recurrent gains (〉 25 %) in 1q, 2p, 7q, 13q, 17q and 20pter-qter. Regions of loss with a frequency (〉 25%) included 1p, 6q, 7p, 9p, 9q, 1011q, 12q, 13q, 15q, 16p, 17p, 18p, and 18q consistent with other studies. Only 30%-50% of the genes residing in the gained or deleted regions showed corresponding increased or decreased expression. Many of the genes with increased expression were involved in cell proliferation, growth and energy metabolic processes important for the neoplastic cells. In deleted regions, genes showing decreased expression included transcription factors or repressors (e.g. SP4, PRDM1, NCOR1 and ZNF10), tumor suppressors or negative regulators of the cell cycle (e.g. CDKN2C, CDKN2A, CDKN2B, CHFR and FOXO1A). 6q21 is a frequent deleted region and we found a minimal region of involvement including only three known genes (PRDM1, ATG5 and AIM1), that had consistent low expression. Sequence analysis of these genes revealed mutations in PRDM1 and AIM1 in two out of eight cell lines resulting in truncated proteins of PRDM1 and changes in conserved amino acid sequences of AIM1. Only one cell line with a point mutation in a non-conserved region in ATG5 was detected. DNA methylation analysis showed that the promoter of PRDM1 was highly methylated in NK cell lines having low PRDM1 expression. Reversal of promoter methylation with decitabine treatment resulted in increased PRDM1 transcription consistent with down-regulation of PRDM1 expression on promoter methylation. Finally, we observed progressive up-regulation of PRDM1 expression in primary NK cells in response to IL2 treatment suggestive of a role of PRDM1 on the regulation of NK-cell activation. Conclusion: Combination of high resolution genomic and transcriptional profiling in NK-cell malignancies has provided evidence of a general tumor promoting effect of genomic copy number alterations as well as the identification of candidate genes in a commonly deleted region in 6q. Specifically, we propose PRDM1 as a tumor suppressor gene in NK cell malignancies and loss-offunction of PRDM1 in combination with the haplo-insufficiency of ATG5 might have significant roles in the pathogenesis of NK-cell malignancies.

Description: Killer immunoglobulin-like receptors (KIRs) play an essential role in the regulation of natural killer cell functions. KIR genes are highly polymorphic in nature, showing both haplotypic and allelic variations among people. We demonstrated in both in vitro and in vivo models a significant heterogeneity in function among different KIR2DL1 alleles, including their ability to inhibit YT-Indy cells from degranulation, interferon γ production, and cytotoxicity against target cells expressing the HLA-Cw6 ligand. Subsequent experiments showed that the molecular determinant was an arginine residue at position 245 (R245) in its transmembrane domain that mechanistically affects both the efficiency of inhibitory signaling and durability of surface expression. Specifically, in comparison with R245-negative alleles, KIR2DL1 that included R245 recruited more Src-homology-2 domain-containing protein tyrosine phosphatase 2 and β-arrestin 2, showed higher inhibition of lipid raft polarization at immune synapse, and had less down-regulation of cell-surface expression upon interaction with its ligand. Thus, our findings provide novel insights into the molecular determinant of KIR2DL1 and conceivably a fundamental understanding of KIR2DL1 allelic polymorphism in human disease susceptibility, transplant outcome, and donor selection.

Description: Abstract 679 Background: Peripheral T-cell lymphoma (PTCL) represents approximately 10–12% of all non-Hodgkin lymphoma (NHL) in the Western world, with a higher incidence in Asian populations. The World Health Organization classification recognizes a number of distinctive subtypes of PTCL including angioimmunoblastic T-cell lymphoma (AITL), anaplastic large cell lymphoma (ALCL), adult T-cell leukemia/lymphoma (ATLL), extranodal NK/T-cell lymphoma of nasal type (ENKTCL), and many other rare entities that present mainly as extranodal PTCL. However, with current immunophenotypic and molecular markers, about 30–50% of PTCL cases are not classifiable and are categorized as PTCL-not otherwise specified (PTCL-NOS). With the exception of ALK(+)ALCL, the PTCLs generally have a poor outcome and, thus a better understanding of the biology of these diseases is greatly needed to improve the long-term survival of these patients. Methods: In the current study, we performed gene expression profiling analysis on a large and well- characterized series of PTCL and ENKTCL cases (n=372) from the Lymphoma Leukemia Molecular Profiling Project (LLMPP), the International Peripheral T-cell Lymphoma Project (IPTCL) and other major institutions to define robust molecular classifiers, oncogenic pathways and prognosticators for the more common PTCL entities, as well as unique molecular and prognostic subgroups within PTCL-NOS. Molecular signatures for diagnosis and prognosis were generated in training data sets and validated in separate cohorts. Results: Robust molecular classifiers for AITL, two types of systemic ALCL (ALK(+) and ALK(-)), ATLL and ENKTCL were identified (Figure 1). These classifiers reflect the pathobiology of the tumor cells, as well as their microenvironment, and represent a refinement of what we reported previously (Iqbal et.al Blood, 2010; Iqbal et.al Leukemia. 2011). Importantly, ALK(-)ALCL can be differentiated from ALK(+)ALCL and PTCL-NOS with a unique gene expression signature. Approximately 14% of PTCL-NOS were re-classified as ALK(-)ALCL and showed expression of CD30 protein, TIA-1 or granzyme B by immunohistochemistry. ENKTCL can be separated molecularly into NK-cell lymphoma and gd-PTCL, the latter of which was also identified in 9% of PTCL-NOS. The remaining PTCL-NOS cases could be separated into two major subgroups related to T-cell differentiation and characterized by either high expression of GATA3 (30%) or TBX21(T-BET) (45%) and many of the corresponding target genes (Figure 2). Cases with high expression of GATA3 had poor overall survival and showed enriched Wnt and mTOR pathways, but no prominent microenvironment signature. The high TBX21 subgroup had a remarkably good outcome for patients with a high plasma cell-like gene expression signature, but poor overall survival when expressing a high cytotoxic signature (Figure 3). The molecular prognosticator for AITL largely reflected the role of the tumor microenvironment, with the presence of a high B-cell signature correlating with favorable outcome, whereas high dendritic cell/monocyte signatures were associated with inferior survival. Conclusion: We have organized the most comprehensive molecular profiling study of PTCL, and have not only refined the molecular diagnostic and prognostic signatures for the common subtypes of PTCL, but also segregated PTCL-NOS in meaningful biological and prognostic subtypes. Molecular diagnostic and prognostic signatures of PTCL frequently include components of the tumor-host interactions, highlighting the importance of the microenvironment in PTCL biology. This study provides an important framework for additional analysis to identify novel therapeutic targets to improve the outcome of patients with PTCL. Disclosures: No relevant conflicts of interest to declare.

Description: Key Points Diagnostic signatures for PTCL subtypes and 2 novel subgroups with distinct oncogenic pathway and prognostic importance in PTCL-NOS were identified. Demonstrated that ALK(–) ALCL is a distinct molecular entity and the tumor microenvironment has prognostic significance in AITL patients.

Description: Abstract 313 Background: Natural Killer (NK) cell lymphomas (NKCL) are rare with aggressive clinical behavior. The majority of these cases belong to extra-nodal NK/T-cell lymphoma of nasal type (ENKTL) of the current World Health Organization (WHO) classification scheme. ENKTL also includes peripheral T-cell lymphomas (PTCL) that are similar in many respects to the NK cell counterpart. Due to rarity of the disease and difficulty in obtaining adequate biopsy specimens, the molecular mechanisms underlining ENKTL are largely unknown. We profiled a series of NK-cell lymphoma cases and many well- characterized cell lines of NK- and T-cell lineages to define molecular classifiers that can distinguish NKCL from PTCL, including lymphomas of cytotoxic T-cells. We also evaluated oncogenic pathways in these tumors and the therapeutic potential of a novel inhibitor of a cell cycle regulator (aurora kinase A). Patients and Methods: The gene expression profiling (GEP) of ENKTL (n=21) and PTCL-U (n=50) cases were performed using HG U133 plus 2 arrays (Affymetrix Inc, CA). GEP of other PTCL subtypes (n=90), normal NK and T cells (resting and activated), NK and T cell lines (n=14) and indolent NK- cell/large granular lymphocytic proliferation (NK-LGLP) (n=5) were used for comparative analysis. Immunohistochemistry (IHC) was used to validate the GEP findings. A novel aurora-kinase-A inhibitor (MK-8745) was obtained from Merck & Co (Merck & Co., Inc. NJ, USA) and incubated with the cell lines for 2 -24 hours at 0.1-1 μM concentrations. Results: The ENKTL showed a male predominance (2:1) with a median age of 55 years at diagnosis and aggressive clinical behavior [5-year OS (

Description: Mechanistic target of rapamycin complex 1 (mTORC1) is a central integrator of nutrient and growth factor inputs that controls cell growth in all eukaryotes. Rapamycin and its analogs (rapalogs) have been approved for the treatment of relapsed mantle cell lymphoma. A large proportion of aggressive B-cell lymphoma patients, however, respond poorly to rapalogs. The second generation of mTOR inhibitors function as ATP-competitive inhibitors (TORi), directly targeting the mTOR catalytic site. TORis have been proven to be more effective than rapalogs in cancer treatment. However, the mechanism underlying the cytotoxic effect of TORis in aggressive B-cell lymphomas remains unclear. In this study, we demonstrated that TORi-induced apoptosis is predominantly dependent on loss of mTORC1-mediated 4EBP phosphorylation. Knocking out Rictor, a key component of mTORC2, or inhibiting p70S6K has little effect on TORi-induced apoptosis. In contrast, increasing the EIF4E:4EBP ratio by either overexpressing EIF4E or knocking out 4EBP1/2 protected lymphoma cells from TORi-induced cytotoxicity. Furthermore, down-regulation of MCL1 and BCL-XL expression plays an important role in TORi-induced apoptosis whereas BCL-2, in cells with high expression, confers resistance to TORi treatment. Based on the mechanism study, we demonstrated that BH3 profiling, primarily NOXA and HRK stimulation, can effectively predict the cytotoxicity of the TORi in lymphoma cells. Also, in combination with pro-apoptotic drugs, especially BCL-2 inhibitors, the TORi exerted powerful anti-tumor effects both in vitro and in vivo. Taken together, this study provides mechanistic insight in TORi treatment in aggressive B-cell lymphoma and identified a mean to predict and improve its effectiveness clinically. Disclosures No relevant conflicts of interest to declare.