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T-cell/histiocyte-rich large B-cell lymphoma (TCRLBCL) is an aggressive variant of diffuse large B-cell lymphoma (DLBCL) characterized by rare malignant B cells within a robust but ineffective immune cell infiltrate. The mechanistic basis of immune escape in TCRLBCL is poorly defined and not targeted therapeutically. We performed a genetic and quantitative spatial analysis of the PD-1/PD-L1 pathway in a multi-institutional cohort of TCRLBCLs and found that malignant B cells harbored PD-L1/PD-L2 copy gain or amplification in 64% of cases, which was associated with increased PD-L1 expression (P = .0111). By directed and unsupervised spatial analyses of multiparametric cell phenotypic data within the tumor microenvironment, we found that TCRLBCL is characterized by tumor-immune “neighborhoods” in which malignant B cells are surrounded by exceptionally high numbers of PD-L1–expressing TAMs and PD-1+ T cells. Furthermore, unbiased clustering of spatially resolved immune signatures distinguished TCRLBCL from related subtypes of B-cell lymphoma, including classic Hodgkin lymphoma (cHL) and DLBCL-NOS. Finally, we observed clinical responses to PD-1 blockade in 3 of 5 patients with relapsed/refractory TCRLBCL who were enrolled in clinical trials for refractory hematologic malignancies (NCT03316573; NCT01953692), including 2 complete responses and 1 partial response. Taken together, these data implicate PD-1 signaling as an immune escape pathway in TCRLBCL and also support the potential utility of spatially resolved immune signatures to aid the diagnostic classification and immunotherapeutic prioritization of diverse tumor types. Key Points: • Spatially resolved signatures of PD-1/PD-L1 signaling in the tumor microenvironment define T-cell/histiocyte-rich large B-cell lymphoma. • Three of 5 patients with relapsed/refractory TCRLBCL showed objective clinical responses to single-agent PD-1 blockade (pembrolizumab).

Double-hit lymphomas (DHLs) and double-expressor lymphomas (DELs) are associated with resistance to frontline and salvage immunochemotherapy, as well as autologous stem cell transplantation (SCT). We hypothesized that allogeneic SCT (alloSCT) could overcome the chemoresistance associated with DEL/DHL. We retrospectively studied the impact of DEL/DHL status in a multicenter cohort of patients who underwent alloSCT for relapsed/refractory (rel/ref) aggressive B cell non-Hodgkin lymphoma (B-NHL). Seventy-eight patients transplanted at 3 centers in whom tumor tissue was available for immunohistochemistry and fluorescence in situ hybridization were enrolled; 47% had DEL and 13% had DHL. There were no significant differences in 4-year progression-free (PFS) or overall survival (OS) between patients with DEL compared with patients without DEL (PFS 30% versus 39%, P = .24; OS 31% versus 49%, P = .17) or between patients with DHL compared with patients without DHL (PFS 40% versus 34%, P = .62; OS 50% versus 38%, P = .46). The lack of association between DEL or DHL and outcome was confirmed in multivariable models, although inadequate sample size may have limited our ability to detect significant differences. In our cohort alloSCT produced durable remissions in patients with rel/ref aggressive B-NHL irrespective of DEL and DHL status, justifying its consideration in the treatment of patients with rel/ref DEL/DHL.

Purpose Double-hit lymphomas (DHLs) and double-expressor lymphomas (DELs) are subtypes of diffuse large B-cell lymphoma (DLBCL) associated with poor outcomes after standard chemoimmunotherapy. Data are limited regarding outcomes of patients with relapsed or refractory (rel/ref) DEL or DHL who undergo autologous stem-cell transplantation (ASCT). We retrospectively studied the prognostic impact of DEL and DHL status on ASCT outcomes in patients with rel/ref DLBCL. Methods Patients with chemotherapy-sensitive rel/ref DLBCL who underwent ASCT at two institutions and in whom archival tumor material was available were enrolled. Immunohistochemistry for MYC, BCL2, and BCL6 and fluorescence in situ hybridization (FISH) for MYC were performed. In cases with MYC rearrangement or copy gain, FISH for BCL2 and BCL6 was also performed. Results A total of 117 patients were included; 44% had DEL and 10% had DHL. DEL and DHL were associated with inferior progression-free survival (PFS), and DHL was associated with poorer overall survival (OS). The 4-year PFS in patients with DEL compared with those with non-DEL was 48% versus 59% ( P = .049), and the 4-year OS was 56% versus 67% ( P = .10); 4-year PFS in patients with DHL compared with those with non-DHL was 28% versus 57% ( P = .013), and 4-year OS was 25% versus 61% ( P = .002). The few patients with concurrent DEL and DHL had a poor outcome (4-year PFS, 0%). In multivariable models, DEL and DHL were independently associated with inferior PFS, whereas DHL and partial response ( v complete response) at transplant were associated with inferior OS. Conclusion DEL and DHL are both associated with inferior outcomes after ASCT in patients with rel/ref DLBCL. Although ASCT remains a potentially curative approach, these patients, particularly those with DHL, are a high-risk subset who should be targeted for investigational strategies other than standard ASCT.

Immune checkpoint therapies targeting CTLA-4 and PD-1 have proven effective in cancer treatment. However, the identification of biomarkers for predicting clinical outcomes and mechanisms to overcome resistance remain as critical needs. Angiogenesis is increasingly appreciated as an immune modulator with potential for combinatorial use with checkpoint blockade. Angiopoietin-2 (ANGPT2) is an immune target in patients and is involved in resistance to anti-VEGF treatment with the monoclonal antibody bevacizumab. We investigated the predictive and prognostic value of circulating ANGPT2 in metastatic melanoma patients receiving immune checkpoint therapy. High pretreatment serum ANGPT2 was associated with reduced overall survival in CTLA-4 and PD-1 blockade–treated patients. These treatments also increased serum ANGPT2 in many patients early after treatment initiation, whereas ipilimumab plus bevacizumab treatment decreased serum concentrations. ANGPT2 increases were associated with reduced response and/or overall survival. Ipilimumab increased, and ipilimumab plus bevacizumab decreased, tumor vascular ANGPT2 expression in a subset of patients, which was associated with increased and decreased tumor infiltration by CD68+ and CD163+ macrophages, respectively. In vitro, bevacizumab blocked VEGF-induced ANGPT2 expression in tumor-associated endothelial cells, whereas ANGPT2 increased PD-L1 expression on M2-polarized macrophages. Treatments elicited long-lasting and functional antibody responses to ANGPT2 in a subset of patients receiving clinical benefit. Our findings suggest that serum ANGPT2 may be considered as a predictive and prognostic biomarker for immune checkpoint therapy and may contribute to treatment resistance via increasing proangiogenic and immunosuppressive activities in the tumor microenvironment. Targeting ANGPT2 provides a rational combinatorial approach to improve the efficacy of immune therapy. Cancer Immunol Res; 5(1); 17–28. ©2016 AACR.

The activated B cell (ABC-like) subtype of diffuse large B cell lymphoma (DLBCL) is characterized by chronic activation of signaling initiated by immunoglobulin μ (IgM). By analyzing the DNA copy number profiles of 1000 DLBCL tumors, we identified gains of 18q21.2 as the most frequent genetic alteration in ABC-like DLBCL. Using integrative analysis of matched gene expression profiling data, we found that the TCF4 (E2-2) transcription factor gene was the target of these alterations. Overexpression of TCF4 in ABC-like DLBCL cell lines led to its occupancy on immunoglobulin (IGHM) and MYC gene enhancers and increased expression of these genes at the transcript and protein levels. Inhibition of TCF4 activity with dominant-negative constructs was synthetically lethal to ABC-like DLBCL cell lines harboring TCF4 DNA copy gains, highlighting these gains as an attractive potential therapeutic target. Furthermore, the TCF4 gene was one of the top BRD4-regulated genes in DLBCL cell lines. BET proteolysis-targeting chimera (PROTAC) ARV771 extinguished TCF4, MYC, and IgM expression and killed ABC-like DLBCL cells in vitro. In DLBCL xenograft models, ARV771 treatment reduced tumor growth and prolonged survival. This work highlights a genetic mechanism for promoting immunoglobulin signaling in ABC-like DLBCL and provides a functional rationale for the use of BET inhibitors in this disease.

Advances in sequencing technologies permit the analysis of a larger selection of genes for preconception carrier screening. The study was designed as a sequential carrier screen using genome sequencing to analyze 728 gene-disorder pairs for carrier and medically actionable conditions in 131 women and their partners (n = 71) who were planning a pregnancy. We report here on the clinical laboratory results from this expanded carrier screening program. Variants were filtered and classified using the latest American College of Medical Genetics and Genomics (ACMG) guideline; only pathogenic and likely pathogenic variants were confirmed by orthologous methods before being reported. Novel missense variants were classified as variants of uncertain significance. We reported 304 variants in 202 participants. Twelve carrier couples (12/71 couples tested) were identified for common conditions; eight were carriers for hereditary hemochromatosis. Although both known and novel variants were reported, 48% of all reported variants were missense. For novel splice-site variants, RNA-splicing assays were performed to aid in classification. We reported ten copy-number variants and five variants in non-coding regions. One novel variant was reported in F8, associated with hemophilia A; prenatal testing showed that the male fetus harbored this variant and the neonate suffered a life-threatening hemorrhage which was anticipated and appropriately managed. Moreover, 3% of participants had variants that were medically actionable. Compared with targeted mutation screening, genome sequencing improves the sensitivity of detecting clinically significant variants. While certain novel variant interpretation remains challenging, the ACMG guidelines are useful to classify variants in a healthy population.

Purpose Hodgkin Reed-Sternberg (HRS) cells evade antitumor immunity by multiple means, including gains of 9p24.1/ CD274(PD-L1)/ PDCD1LG2(PD-L2) and perturbed antigen presentation. Programmed death 1 (PD-1) receptor blockade is active in classic Hodgkin lymphoma (cHL) despite reported deficiencies of major histocompatibility complex (MHC) class I expression on HRS cells. Herein, we assess bases of sensitivity to PD-1 blockade in patients with relapsed/refractory cHL who were treated with nivolumab (anti–PD-1) in the CheckMate 205 trial. Methods HRS cells from archival tumor biopsies were evaluated for 9p24.1 alterations by fluorescence in situ hybridization and for expression of PD ligand 1 (PD-L1) and the antigen presentation pathway components—β2-microglobulin, MHC class I, and MHC class II—by immunohistochemistry. These parameters were correlated with clinical responses and progression-free survival (PFS) after PD-1 blockade. Results Patients with higher-level 9p24.1 copy gain and increased PD-L1 expression on HRS cells had superior PFS. HRS cell expression of β2-microglobulin/MHC class I was not predictive for complete remission or PFS after nivolumab therapy. In contrast, HRS cell expression of MHC class II was predictive for complete remission. In patients with a > 12-month interval between myeloablative autologous stem-cell transplantation and nivolumab therapy, HRS cell expression of MHC class II was associated with prolonged PFS. Conclusion Genetically driven PD-L1 expression and MHC class II positivity on HRS cells are potential predictors of favorable outcome after PD-1 blockade. In cHL, clinical responses to nivolumab were not dependent on HRS cell expression of MHC class I.

NF-κB is an evolutionarily conserved eukaryotic transcription factor that plays a role in many important developmental and immune-related processes by activating target gene expression. The goal of these experiments was to define the sequences required for a sea anemone NF-κB's intrinsic transactivation activity by using mutant proteins with serial deletions of the N- and C-terminal sequences. Deletion mutants were constructed that were missing the C-terminal 15, 32 or 47 amino acids (aa) or the N-terminal 17, 27 or 47 aa of the 440 aa NF-κB protein from the starlet sea anemone, Nematostella vectensis (Nv), a simple model organism in the phylum Cnidaria. These Nv-NF-κB mutants were expressed as GAL4 fusion proteins in yeast, and their transactivation activities were assessed by LacZ reporter gene assays. The deletion of 47 aa from either the N terminus or the C terminus of NF-κB completely inactivates the transactivation function of Nv-NF-κB. In addition, we identified proline-258 in the center ...

Ethnopharmacological relevance The root of Bupleurum falcatum L. (BF) has been used in traditional Korean and Chinese medicines for over 2000 years to treat infections, fever, and chronic liver diseases. Among the many active compounds in BF ethanol extract (BFE), saikosaponins exert pharmacological activities including anti-inflammatory effects. Activated microglial cells release a variety of pro-inflammatory substances, leading to neuronal cell death and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. The aim of the present study was to investigate the mechanism of the anti-neuroinflammatory effects of BFE using lipopolysaccharide (LPS)-stimulated microglial cells and LPS-intraperitoneal injected C57BL/6 mice. Materials and methods Dried roots of BF were extracted with 70% ethanol (tenfold volume) on a stirring plate for 24 h at room temperature to prepare BFE. Pure saikosaponins (SB3, SB4, and SD) were prepared by solvent extraction and column chromatography fractionation. BV2 murine microglial cells were treated with BFE or saikosaponins for 4 h and stimulated with LPS. Generation of nitric oxide (NO), inflammatory cytokines, and reactive oxygen species (ROS) from activated microglial cells were monitored. The effects of BFE on NF-κB activation were determined using RT-PCR, reporter assay, and immunostaining. The in vivo effects of BFE were also assessed by immunohistochemical staining of tissue sections from LPS-injected mouse brains. Results Treatment with BFE or saikosaponins dose-dependently attenuated LPS-induced production of NO, iNOS mRNA, and ROS by 30–50%. They reduced LPS-mediated increases in the mRNA levels of IL-6, IL-1β, and TNF-α by approximately 30–70% without affecting cell viability, and decreased LPS-mediated NF-κB activity via reducing p65/RELA mRNA, transcriptional activity, and nuclear localization of NF-κB. BFE also reduced LPS-induced activation of microglia and astrocytes in the hippocampus and substantia nigra of LPS-injected mice. Conclusion Our data suggest that BFE may be effective for reducing neuroinflammation-mediated neurodegeneration through suppressing NF-κB-mediated inflammatory pathways.

The activated B-cell (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) is characterized by the chronic activation of signaling initiated by immunoglobulin-μ (IgM). By analyzing DNA copy profiles of 1,000 DLBCLs, we identified gains of 18q21.2 as the most frequent genetic alteration in ABC-like DLBCL. We show that these alterations target the TCF4 (E2-2) transcription factor, and that over-expression of TCF4 leads to its occupancy on immunoglobulin gene enhancers and increased expression of IgM at the transcript and protein level. The TCF4 gene is one of the top BRD4-regulated genes in DLBCL. Using a BET proteolysis-targeting chimera (PROTAC) we show that TCF4 and IgM expression can be extinguished, and ABC-like DLBCL cells can be killed in vitro and in vivo. This highlights a novel genetic mechanism for promoting immunoglobulin signaling in ABC-like DLBCL and provides a functional rationale for the use of BET inhibitors in this disease.

In classical Hodgkin lymphoma (cHL), malignant Hodgkin Reed–Sternberg (HRS) cells evade antitumor immunity by multiple mechanisms, including perturbed antigen presentation and enhanced PD-1 signaling. HRS cell expression of the PD-1 ligands is attributable, in part, to copy number alterations of 9p24.1/CD274(PD-L1)/PDCD1LG2(PD-L2). Amplification of PD-L1/PD-L2 is associated with advanced clinical stage and inferior progression-free survival (PFS) following first-line (induction) therapy. The relationships between altered expression of β2-microglobulin (β2M), MHC class I, and MHC class II by HRS cells, PD-L1/PD-L2 amplification, and clinical outcome in cHL are poorly defined. We assessed these variables in diagnostic biopsy specimens from 108 patients with cHL who received uniform treatment and had long-term follow-up and found decreased/absent expression of β2M/MHC class I in 79% (85/108) and decreased/absent expression of MHC class II in 67% (72/108) of cases. Patients with decreased/absent β2M/MHC class I had shorter PFS, independent of PD-L1/PD-L2 amplification and advanced stage. Decreased or absent MHC class II was unrelated to outcome. These results suggest that MHC class I–mediated antigen presentation by HRS cells is an important component of the biological response to standard chemo/radiotherapy. The paucity of β2M/MHC class I expression on HRS cells also prompts speculation regarding alternative mechanisms of action of PD-1 blockade in cHL. Cancer Immunol Res; 4(11); 910–6. ©2016 AACR.

Evaluating the pathogenicity of a variant is challenging given the plethora of types of genetic evidence that laboratories consider. Deciding how to weigh each type of evidence is difficult, and standards have been needed. In 2015, the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) published guidelines for the assessment of variants in genes associated with Mendelian diseases. Nine molecular diagnostic laboratories involved in the Clinical Sequencing Exploratory Research (CSER) consortium piloted these guidelines on 99 variants spanning all categories (pathogenic, likely pathogenic, uncertain significance, likely benign, and benign). Nine variants were distributed to all laboratories, and the remaining 90 were evaluated by three laboratories. The laboratories classified each variant by using both the laboratory's own method and the ACMG-AMP criteria. The agreement between the two methods used within laboratories was high (K-alpha = 0.91) with 79% concordance. However, there was only 34% concordance for either classification system across laboratories. After consensus discussions and detailed review of the ACMG-AMP criteria, concordance increased to 71%. Causes of initial discordance in ACMG-AMP classifications were identified, and recommendations on clarification and increased specification of the ACMG-AMP criteria were made. In summary, although an initial pilot of the ACMG-AMP guidelines did not lead to increased concordance in variant interpretation, comparing variant interpretations to identify differences and having a common framework to facilitate resolution of those differences were beneficial for improving agreement, allowing iterative movement toward increased reporting consistency for variants in genes associated with monogenic disease.

Introduction: T-cell/histiocyte-rich large B-cell lymphoma (TCRLBCL) is an aggressive large B cell lymphoma that typically presents with disseminated disease. In contrast to diffuse large B-cell lymphoma, not otherwise specified (DLBCL), TCRLBCL is characterized histologically by rare malignant B-cells within a robust but ineffective inflammatory background composed of numerous T cells and macrophages. TCRLBCL shows a "tolerogenic" immune signature by gene expression profiling, as well as frequent upregulation of PD-L1 (Van Loo et al. PMID: 19797726; Chen et al. PMID: 23674495). Although these features suggest that active immune evasion is central to TCRLBCL pathogenesis, its mechanistic basis is poorly understood. Accordingly, we performed an integrated analysis of tumor genetics and cell-cell interactions within the tumor microenvironment to comprehensively study PD-1:PD-L1 interactions in a multi-institutional cohort of TCRLBCL. Methods: 34 cases of TCRLBCL were identified from the pathology archives of four academic medical centers. Control cohorts containing 21 cases of DLBCL and 106 cases of classic Hodgkin Lymphoma (CHL) were used as comparators. An established fluorescence in situ hybridization (FISH) assay was used to identify copy number changes and structural rearrangements of CD274 (PD-L1) and PDCD1LG2 (PD-L2) on chromosome 9p24.1, which represents the primary genetic mechanism of PD-L1/L2 expression in CHL (Roemer et al. PMID: 27069084). Tumor-specific expression of PD-L1 and PD-L2 protein was assessed by immunohistochemistry (IHC) and scoring by two pathologists using a modified H-score (percentage of positive tumor cells [0-100%] multiplied by the mean staining intensity [0-3+]). The topology of PD-L1/PD-1 expression and cell-cell interactions in the tumor microenvironment was determined by multispectral immunofluorescence (IF) microscopy and spatial image analysis, as previously performed for CHL (Carey et al. PMID: 28893733). Results: By FISH, copy gain or amplification of PD-L1 and PD-L2 was identified in 22/34 (64.7%) cases of TCRLBCL (Figure 1A) and was associated with a 4.9-fold increase in tumor PD-L1 expression relative to cases with disomy or polysomy (mean PD-L1 H-score 72 vs 14.7, p = 0.02). A rearrangement of PD-L2 was identified in one case and associated with diffuse expression of PD-L2. These findings contrasted with those observed in the DLBCL cohort, which showed a low overall frequency of 9p24.1 copy gain/amplification (5/21 cases, 23.8%) and only minimal tumor PD-L1 expression (mean PD-L1 H-score 15.6), and were intermediate to those observed in CHL, which shows near universal copy gain/amplification of 9p24.1 (98/106 cases, 92%) and extensive tumor PD-L1 expression (mean PD-L1 H-score 143.7; Figure 1B). By multispectral IF, TCRLBCL showed prominent infiltration by PD-L1+ tumor-associated macrophages (TAM) (Figure 1C), which were 5.5-fold increased relative to DLBCL and 6.6-fold increased relative to CHL (p < 0.001). TCRLBCL also showed marked infiltration by PD-1+ T cells, which were 12.3-fold increased relative to DLBCL and 3.4-fold increased relative to CHL (p < 0.001). By spatial analysis, PD-L1+ TAMs in TCRLBCL were located in closer proximity to tumor cells than PD-L1- TAMs (p < 0.001, Figure 1D-E) and also showed frequent direct interactions with PD-1+ T cells. These findings contrasted with those in DLBCL, where no local enrichment of PD-L1+ TAMs or PD-1+ T cells was identified, and were similar but more prominent than those observed in CHL. Conclusion: TCRLBCL is characterized by recurrent gains of PD-L1 and PD-L2 on chromosome 9p24.1 in association with tumor-specific expression of PD-1 ligands, as well as prominent infiltration by PD-L1+ TAMs and PD-1+ T cells. PD-L1+ TAMs in TCRLBCL are enriched around individual tumors cells and also show frequent direct interactions with PD-1+ T cells, consistent with the establishment of an immunoevasive-niche. These findings contrast with those observed in DLBCL and are most similar to those identified in CHL. Relative to CHL, however, TCRLBCL shows less frequent gains of 9p24.1 and tumor cell expression of PD-L1, and a greater degree of infiltration by PD-L1+ TAMs and PD-1+ T cells. These findings suggest that the PD-1:PD-L1 pathway is central to immune evasion in TCRLBCL and highlight the need to test the clinical efficacy of PD-1 blockade in this patient population. Disclosures Griffin: Moderna Therapeutics: Consultancy. Freeman:Novartis: Patents & Royalties; AstraZeneca: Patents & Royalties; Dako: Patents & Royalties; Roche: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers-Squibb: Patents & Royalties; Merck: Patents & Royalties; EMD-Serono: Patents & Royalties; Roche: Patents & Royalties; Xios: Membership on an entity's Board of Directors or advisory committees; Boehringer-Ingelheim: Patents & Royalties; Bristol-Myers-Squibb: Membership on an entity's Board of Directors or advisory committees; Origimed: Membership on an entity's Board of Directors or advisory committees. Hodi:Merck: Consultancy. Shipp:Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Research Funding; Bayer: Research Funding; AstraZeneca: Honoraria. Rodig:KITE: Research Funding; Affimed: Research Funding; Merck: Research Funding; Bristol Myers Squibb: Research Funding.

Background: Double-hit lymphomas (DHL) - diffuse large B-cell lymphomas (DLBCL) with concurrent rearrangements of MYC and BCL2 and/or BCL6, and double-expressor lymphomas (DEL) - DLBCL with co-expression of MYC and BCL2 by immunohistochemistry (IHC), are associated with poor outcomes after standard chemoimmunotherapy. We have previously demonstrated that patients with relapsed or refractory (rel/ref) DHL and DEL have inferior outcomes after autologous stem cell transplantation (autoSCT) compared to patients with neither DEL nor DHL [Herrera et al, ASH 2015]. Although patients with DEL and DHL have inferior outcomes after chemotherapy-based treatment modalities, we hypothesized that allogeneic SCT (alloSCT) could potentially abrogate that negative prognostic impact. Data are extremely limited regarding the outcome of patients with DHL who undergo alloSCT, and no study has examined alloSCT outcomes in patients with DEL. We studied alloSCT outcomes in a multicenter cohort of rel/ref DLBCL patients and evaluated the prognostic impact of DEL and DHL status. Methods: We retrospectively studied patients with rel/ref DLBCL, transformed indolent lymphoma (TIL), or high-grade B-cell lymphoma unclassified (BCLU) who had available tumor tissue and underwent alloSCT at Dana-Farber Cancer Institute, Massachusetts General Hospital, or City of Hope between 1/2000 and 5/2014. IHC for MYC, BCL2, and BCL6 were performed. DEL was defined as MYC expression in ≥ 40% tumor cells and BCL2 expression in ≥ 50% tumor cells. FISH for MYC was performed using dual-color break-apart probes. Cases with MYC-rearrangement had FISH performed for BCL2 and BCL6 using break-apart probes. Rearrangement was defined as ≥ 10% nuclei with break-apart signals. DHL was defined as concurrent rearrangement of MYC and BCL2 and/or BCL6. Results: Tumor tissue was available in 103 patients, among whom we could obtain complete IHC and FISH data in 74. In these 74 patients, the median age was 54 years (range 24-69); 69% had DLBCL/BCLU whereas 31% had TIL; the median number of prior therapies was 4 (range 2-9); 58% had prior autoSCT; 73% were in complete or partial remission (CR/PR) at alloSCT; 77% had reduced intensity conditioning (RIC); 78% had a matched related or unrelated donor. 4y progression-free survival (PFS), overall survival (OS), cumulative incidence of relapse (CIR), and non-relapse mortality (NRM) in the overall cohort were 34%, 40%, 44% and 22%, respectively, with a median follow-up of 46 months for survivors. 47% of patients had DEL and 14% had DHL. The proportion of patients with a history of primary refractory disease was higher among DHL (60%) and DEL (52%) patients compared to nonDHL/nonDEL patients (37%), although the difference was not significant (p=0.3). Overall, there were no significant differences in clinical characteristics between patients with DHL, DEL, and nonDHL/nonDEL. Neither DEL nor DHL were significantly associated with outcome (Figure). The 4y PFS in DEL v non-DEL patients was 29% v 39% (p=0.2), 4y OS 30% v 49% (p=0.11), 4y CIR 50% v 40% (p=0.3), and 4y NRM 21% v 22% (p=1.0). The 4y PFS in DHL v non-DHL patients was 40% v 33% (p=0.6), OS 50% v 37% (p=0.4), CIR 40% v 45% (p=0.9), and NRM 20% v 22% (p=0.8). In multivariable Cox models for PFS and OS, age ≥ 55 (PFS: HR 0.4, p=0.002; OS: HR 0.4, p=0.005), refractory disease (not CR/PR) at alloSCT (PFS: HR 2.4, p=0.009; OS HR 2.6, p=0.007), and TIL (PFS HR 0.4, p=0.018; OS HR 0.4, p=0.028) were associated with PFS and OS, but DEL (PFS HR 1.2, p=0.5; OS HR 1.6, p=0.12) and DHL (PFS HR 0.8, p=0.7; OS HR 0.8, p=0.7) were not. We also constructed multivariable competing risk regression models for CIR and NRM. Age, remission status, histology, and conditioning intensity were associated with relapse, while no factor was significantly associated with NRM. Neither DEL (CIR HR 1.2, p=0.7, NRM HR 0.8, p=0.7) nor DHL (CIR HR 1.1, p=0.9, NRM HR 0.8, p=0.8) were associated with either outcome in those models. Conclusions: AlloSCT produced durable remissions in heavily treated rel/ref DLBCL patients, regardless of DEL and DHL status. In our cohort, DEL and DHL status did not have a significant prognostic impact. Although patients with DEL or DHL have poorer outcomes after chemoimmunotherapy and autoSCT, our results suggest that alloSCT may overcome the chemoresistance of double-hit/double-expressor tumors. Figure Progression-Free Survival After AlloSCT in DEL, DHL, and nonDEL/nonDHL Patients Figure. Progression-Free Survival After AlloSCT in DEL, DHL, and nonDEL/nonDHL Patients Disclosures Herrera: Adaptive Biotechnologies: Research Funding; Genentech: Research Funding; Immune Design: Research Funding; Merck: Research Funding; Pharmacyclics: Research Funding; Seattle Genetics: Research Funding. Song:Seattle Genetics: Consultancy. Chen:Genentech: Consultancy, Speakers Bureau; Millenium: Consultancy, Research Funding, Speakers Bureau; Seattle Genetics: Consultancy, Honoraria, Research Funding, Speakers Bureau; Merck: Consultancy, Research Funding. Chen:Incyte Corporation: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding. Koreth:LLS: Research Funding; amgen inc: Consultancy; takeda pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; kadmon corp: Membership on an entity's Board of Directors or advisory committees; prometheus labs inc: Research Funding; millennium pharmaceuticals: Research Funding. Pillai:Trillium Therapeutics: Research Funding. Siddiqi:Janssen Biotech: Research Funding, Speakers Bureau; Seattle Genetics: Speakers Bureau; Juno Therapeutics: Research Funding; Kite Pharma: Research Funding; Acerta Pharma: Research Funding; MedImmune: Research Funding; Genentech: Research Funding; TG Therapeutics: Research Funding. Zain:Seattle Genetics: Consultancy, Speakers Bureau; Celgene: Consultancy, Speakers Bureau. Kwak:XEME BioPharma: Consultancy, Equity Ownership; Antigenics: Equity Ownership; Celltrion: Consultancy; Sella Life Sciences: Consultancy. Nademanee:Celgene: Consultancy; Seattle Genetics: Consultancy, Research Funding. Weinstock:Novartis: Consultancy, Research Funding. Soiffer:Kiadis: Membership on an entity's Board of Directors or advisory committees; Juno: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees. Rodig:Bristol-Myers Squibb: Honoraria, Research Funding; Perkin Elmer: Membership on an entity's Board of Directors or advisory committees. Armand:Roche: Research Funding; Pfizer: Research Funding; Sequenta Inc: Research Funding; Merck: Consultancy, Research Funding; Infinity Pharmaceuticals: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding.

The development of B-cells is a complex process that proceeds through multiple stages and is regulated by a hierarchy of transcription factors and other physiologic signals. Each unique B-cell malignancy can be aligned with a 'normal counterpart' at one or more of these discrete developmental stages. However, with the exception of translocations of transcription factor genes, the genetic basis for this is not well defined. We performed an analysis of high-resolution single nucleotide polymorphism (SNP) microarrays from 694 diffuse large B-cell (DLBCL) tumors to identify significant somatic copy number alterations (SCNA). Through integrative analysis of 249 tumors with matched gene expression profiling (GEP) data, we identified the likely targets of these alterations and found that genes that were targeted by DNA copy number gain were significantly enriched for DNA binding activity and transcription factor function. We extended upon this observation by analyzing SNP microarray data of a further 2,716 tumors from 7 additional subtypes of B-cell malignancy. Through this analysis, we identified patterns of transcription factor alterations that aligned with the differentiation state of the 'normal B-cell counterpart' of each malignancy. This provides evidence that SCNA of B-cell transcription factors may underlie the differentiation state of B-cell malignancies. DLBCL can be divided into two subtypes based upon gene expression profiles that align with either the germinal center B-cell differentiation state (GCB-like) or a post-GCB activated B-cell state (ABC-like). Having observed an enrichment for transcription factor SCNAs in DLBCL, and an alignment between transcription factor alterations and differentiation states in other B-cell malignancies, we hypothesized that SCNAs of transcription factors may also underlie the etiology of these molecular subtypes. By testing for associations between SCNAs and cell of origin subtype, we identified three co-segregating DNA copy number gains that were significantly enriched in the ABC-like subtype. These included gains of the BCL6 and SPIB genes that have been previously observed to be associated with the ABC-like subtype. In addition, we found gains of the TCF4 (E2-2) gene to be significantly enriched in ABC-like tumors. In line with this, TCF4 alterations were significantly associated with reduced overall survival in cohorts of patients treated with either CHOP (n=232, P=0.009) or R-CHOP (n=197, P=0.041). B-cell receptor (BCR) signaling is a key survival pathway in ABC-like DLBCL, and the TCF4 gene has a defined role in promoting the expression of immunoglobulin (Ig) genes that encode the B-cell receptor (BCR). The analysis of paired SCNA and GEP data revealed a significantly higher expression of Ig genes in tumors with TCF4 DNA copy number gain compared to those without, suggesting that normal BCR expression may be deregulated by this genetic alteration. In addition, chromatin-immunoprecipitation sequencing (ChIP-seq) for TCF4 in ABC-like DLBCL cell lines also revealed binding of TCF4 to an Ig gene enhancer region. As BCR signaling can be altered by somatic mutations in the CARD11, CD79B and MYD88 genes, we evaluated the relative representation of these mutations and TCF4 DNA copy number gains using targeted deep sequencing of 124 DLBCL tumors. This revealed that TCF4 DNA copy number gains largely mutually excluded CARD11 mutations, but significantly co-segregated with both MYD88 (FDR=0.005) and CD79B (FDR=0.053) mutations. In addition, we observed significant co-segregation between CD79B and MYD88 mutations (FDR Together these data highlight an association between SCNA of B-cell transcription factors and the differentiation state of the 'normal counterpart' of the respective malignant B-cell. In line with this, we show that DNA copy number gains of the TCF4 transcription factor are associated with the ABC-like subtype of DLBCL, significantly worse overall survival, and increased Ig expression. These characteristics, in addition to the co-association between TCF4 DNA copy number gains and somatic mutations of CD79B and MYD88, suggest that TCF4 may be an important modifier of BCR signaling and contribute to the etiology of ABC-like DLBCL. Disclosures Rosenquist: Gilead Sciences: Speakers Bureau. Lunning:TG Therapeutics: Consultancy; AbbVie: Consultancy; Gilead: Consultancy; Bristol-Myer-Squibb: Consultancy; Juno: Consultancy; Genentech: Consultancy; Spectrum: Consultancy; Celgene: Consultancy; Pharmacyclics: Consultancy. Rodig:Bristol-Myers Squibb: Honoraria, Research Funding; Perkin Elmer: Membership on an entity's Board of Directors or advisory committees. Levy:Kite Pharma: Consultancy; Five Prime Therapeutics: Consultancy; Innate Pharma: Consultancy; Beigene: Consultancy; Corvus: Consultancy; Dynavax: Research Funding; Pharmacyclics: Research Funding.

Background: A subset of malignant tumors are immunogenic but avoid immune surveillance through ectopic expression of the programmed cell death 1 ligands, PD-L1 and PD-L2, that bind PD-1 on effector T-cells to inhibit T-cell activation, a phenotype that is reversible with PD-1 blockade. Co-amplification and co-gain of CD274 (PD-L1) and PDCD1LG2 (PD-L2) on chromosome 9p24.1 provide a genetic basis for PD-1 ligand expression by Reed-Sternberg cells in classical Hodgkin lymphoma, a tumor highly sensitive to PD-1 blockade. We sought to determine whether copy number alterations of CD274 and PDCD1LG2 are a mechanism of PD-1 ligand expression in other tumor types. Methods: We surveyed data derived from a clinically-deployed next generation sequencing assay (OncoPanel) to identify tumors with evidence of selective copy gain of genes located at 9p24.1. Formalin-fixed paraffin-embedded biopsy specimens from available cases were reviewed for tumor content, immunostained for PD-L1, and analyzed with custom probes targeting the CD274 and PDCD1LG2 loci and a commercial probe targeting the centromere of chromosome 9 by flourescence in situ hybridization (FISH). Results: Review of NGS data revealed 171 of 7,070 clinical samples (2.4%) with evidence for selective copy gain of CD274 and/or PDCD1LG2. Tissue was available for analysis in 73 cases, of which 55 were successfully analyzed. Co-amplification and co-gain of CD274 and PDCD1LG2 were observed for 20 (36%) and 18 (33%) of cases, respectively. Polysomy 9 and disomy 9 were observed among 9 (16%) and 2 (4%) cases, respectively. Genetic abnormalities associated with chromosome 9 loss were observed among the remaining cases 6 (11%). PD-L1 IHC revealed positive staining of tumor cells in 36 (65%) cases. Among cases with co-amplification/gain of CD274 and PDCD1LG2, a subset (Co-Amp: 36%; Co-Gain: 28%) exhibited moderate to high PD-L1 expression in significant percentages of tumor cells (Tumor H-score > 50). Tumor types with high PD-L1 expression in the context of co-amplification/gain included carcinomas of the head and neck, bladder, and cervix. Conclusions: Review of over 7000 tumors analyzed by a clinically-deployed NGS platform identifies CD274 and PDCD1LG2 copy gain in a low percentage of a variety of solid tumor types, a subset of which has a corresponding increase of PD-L1 expression. These data suggest that copy gain of CD274 and PDCD1LG2 contributes to PD-1 ligand expression in a subset of solid tumors beyond classical Hodgkin lymphoma. Citation Format: Evisa Gjini, Christine Pak, Alyssa Kelly, Yuling Shi, Neal Lindeman, Frank Kuo, Gordon Freeman, Azra Ligon, Stephen Hodi, Margaret Shipp, Scott Rodig. Recurrent gains of CD274 (PD-L1) and PDCD1LG2 (PD-L2) provide a genetic basis for PD-1 ligand expression in a subset of solid tumors. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4027.