Introduction Despite introduction of innovative immune based therapies, many patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) continue to have poor outcomes. Defining immune changes that occur within tumors at relapse is crucial to understanding treatment failure. To explore the evolution of the tumor microenvironment (TME) across treatment timepoints, we performed comprehensive multiomics analysis encompassing immune gene expression, T-cell receptor (TCR) sequencing and spatial transcriptome analysis in a large Australian cohort of R/R DLBCL patients with paired diagnosis and relapse biopsies. Methods Archived biopsies from 141 clinically annotated R/R DLBCL patients were collected from 6 Australian centres. Gene expression profiling using the Nanostring PanCancer Immune panel of 770 immune-related genes was performed on 125 diagnostic and 124 R/R biopsies (first R/R episode: 102, subsequent R/R episode: 22). Lymphoma Subtype (LST) signature was used to evaluate cell of origin (COO). TCR sequencing was performed on 22 pairs using the Archer Immunoverse RNA assay. Nanostring GeoMx spatial whole transcriptome assay was performed on 17 diagnostic and 6 R/R biopsies, segmented into CD20, CD8, CD4 and CD68 regions. Results 63 R/R patients were assigned germinal centre B cell (GCB) COO, 41 activated B cell (ABC), and 19 were unclassified. Only 2 late relapsing (LR) patients (relapse >12 months post end of treatment [EOT]) had COO discordance. COO was not prognostic at relapse. Differential immune gene expression (corrected for false discovery) on 87 pairs of diagnosis and R/R biopsies demonstrated profound changes in the T cell compartment. T cell associated genes (CD3E, CD5, CD7, CD8A, CXCL9: adj p<0.044), PD-L1 pathway genes (JAK2, STAT3, LCK, RELA, MYD88: adj p<0.037) and the immune checkpoint gene TIGIT (adj p=0.005) were significantly downregulated at relapse. This aligned with Nanostring cell abundance scores demonstrating a marked reduction in overall T cell abundance, in particular total CD8 (p=0.003) and exhausted CD8 T cell subtypes (p=0.0004). Reduction in T cell and checkpoint genes were particularly marked in patients with primary refractory (RF) or early relapsing (ER) disease (relapse <12 months post EOT), whereas LR patients demonstrated limited immune gene expression changes across disease timepoints. Compared to RF/ER patients, LR patients had higher T cell abundance at diagnosis (p=0.0018). This abundance was stable during disease in LR patients, with RF/ER patients showing a further reduction at R/R timepoint (p=0.0187). Analysis of 16 patients with 3 serial biopsies demonstrated an ongoing reduction in overall T cell abundance (p=0.035) and exhausted CD8 T cells (p=0.0125) across treatment episodes. Paired analysis of the T cell repertoire showed preserved diversity across disease timepoints. However, low TCR diversity (Shannon's index) at relapse was predictive of poor overall survival (p=0.038), as we have previously demonstrated in newly diagnosed patients (Keane et al, CCR, 2017). Spatial whole transcriptome pathway analysis of CD8 enriched segments demonstrated reduced immunogenic cell death signalling at relapse, with upstream analysis predicting severe interferon-gamma and tumor-necrosis factor inhibition at relapse. Together these findings suggest reduced anti-tumoral/cytotoxic capacity within the TME at relapse. Reduction in CXCL9 at relapse was only identified in T cell segments (CD8 and CD4), noting high expression of CD8/CXCL9 has been identified as highly specific for positive response to immune checkpoint therapy in solid organ tumor cohorts, as likely markers of neo-antigen reactive T cells (Litchfield et al, Cell, 2021). Conclusions Key differences in the TME are evident in DLBCL at relapse with reduced T cell infiltration and function at relapse demonstrated by gene expression and spatial transcriptome analysis. Reduction in T cell infiltration is not seen however, in late relapsing patients, whom have improved overall survival and higher rates of treatment response. Low T cell diversity is a marker of poor overall survival at relapse. These findings suggest T cell mediated immunity is critical for chemotherapy response in DLBCL and could have implications for predicting responses to newer T cell directed therapies such as bispecific T cell and CART therapies.

In classical Hodgkin lymphoma (cHL), responsiveness to immune-checkpoint blockade (ICB) is associated with specific tumor microenvironment (TME) and peripheral blood features. The role of ICB in nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is not established. To gain insights into its potential in NLPHL, we compared TME and peripheral blood signatures between HLs using an integrative multiomic analysis. A discovery/validation approach in 121 NLPHL and 114 cHL patients highlighted >2-fold enrichment in programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) gene expression for NLPHL versus cHL. Multiplex imaging showed marked increase in intra-tumoral protein expression of PD-1+ (and/or TIGIT+) CD4+ T-cells and PD-1+CD8+ T-cells in NLPHL compared to cHL. This included T-cells that rosetted with lymphocyte predominant (LP) and Hodgkin Reed-Sternberg (HRS) cells. In NLPHL, intra-tumoral PD-1+CD4+ T-cells frequently expressed TCF-1, a marker of heightened T-cell response to ICB. The peripheral blood signatures between HLs were also distinct, with higher levels of PD-1+TIGIT+ in TH1, TH2, and regulatory CD4+ T-cells in NLPHL versus cHL. Circulating PD-1+CD4+ had high levels of TCF-1. Notably, in both lymphomas, highly expanded populations of clonal TIGIT+PD-1+CD4+ and TIGIT+PD-1+CD8+ T-cells in the blood were also present in the TME, indicating that immune-checkpoint expressing T-cells circulated between intra-tumoral and blood compartments. In in vitro assays, ICB was capable of reducing rosette formation around LP and HRS cells, suggesting that disruption of rosetting may be a mechanism of action of ICB in HL. Overall, results indicate that further evaluation of ICB is warranted in NLPHL.

INTRODUCTION:The purpose of the study is to assess the role of preoperative magnetic resonance (MR) imaging on the surgical management of invasive lobular carcinoma (ILC) and to evaluate whether breast density and background parenchymal enhancement (BPE) influence surgical treatment. METHODS:This retrospective study was conducted on 56 patients who were diagnosed with ILC between 2014 and 2020. All patients had mammogram and ultrasound. Preoperative MRI was available in 34 patients. Age, menopausal status, breast density, BPE, multifocality/multicentricity and surgical treatment were collected. RESULTS:Mean pathological tumour size was 36.4 mm (range 5-140 mm). Dense breasts had larger tumours compared to non-dense breasts (P = 0.072). Of the 34 patients with MRI, 6 opted for mastectomy. Of the remaining 28 cases, MRI findings upgraded surgery to mastectomy in 54% (15/28) because mammogram/ultrasound underestimated tumour extent in 25% (7/28), or multifocal/multicentric disease was identified in 29% (8/28). Tumour size was underestimated by MRI in 7% (2/28). In the non-MRI subgroup, 64% (14/22) of patients underwent breast-conserving surgery, but 29% of them (4/14) required a second-stage mastectomy due to extensive margin involvement. There was no difference in mastectomy rate between patients with MRI (62%) and without MRI (55%) (P = 0.061). Tumour size correlation between MRI and histopathology demonstrated an excellent intraclass correlation coefficient (P < 0.001). Surgical treatment recommendation was not significantly impacted by breast density or BPE. CONCLUSION:Breast MRI improves surgical management of patients with ILC in providing additional diagnostic information often missed with standard imaging modalities, and without increasing mastectomy rate. Surgical treatment is not impacted by breast density or BPE.

aspartate aminotransferase 152 units/L, alanine aminotransferase 65 unit/L, bilirubin 14 μ mol/L and albumin 20 g/L. Pro-thrombin time was normal. An abdominal ultrasound did not show evidence of cirrhosis or portal hyperten-sion. Her serum-ascites albumin gradient was low at 4 g/L. She tested negative for viral, autoimmune and metabolic causes of liver disease. Right heart failure, nephrotic syndrome and a protein-losing enteropathy were excluded. Computed tomography of the chest, and pelvis showed no evidence of malignancy. Large count consisting of

Hodgkin lymphoma (HL) comprises two distinct disease entities based on clinical, morphologic and genotypic characteristics. Relative to classical Hodgkin Lymphoma (cHL), nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is rare, and its tumor microenvironment (TME) is very poorly characterized. With the exception of rituximab, there are no targeted treatments nor advances in the treatment of NLPHL for decades. Unlike cHL, the utility of immune-checkpoint blockade (ICB) has not been evaluated in NLPHL. Diagnostic samples were collected from 49 NLPHL patients from 4 Australian centres and compared with stage-matched cHL patients (and with normal lymph nodes). An integrative transcriptomic, proteomic, T-cell clonal and functional analysis was performed to enable a comparison of the composition of the TME and its contribution to immune-evasion in NLPHL with cHL. 730 cancer-immune related genes were digitally quantified. Relative to cHL, gene set enrichment analysis identified T-cell receptor (TCR) and immune-checkpoint signaling pathway dysregulation in NLPHL. Most striking was prominent differential expression of the immune-transcriptome, particularly enrichment for programmed cell death-1 (PD-1) and T-cell Ig and ITIM domain (TIGIT) in NLPHL versus cHL. These were also over expressed compared to normal lymph nodes. Consistent with this, there was also upregulation of numerous T-cell markers (CD247, CD3D, GZMK, CD28, EOMES) in NLPHL. In contrast, immunosuppressive macrophage (CD163, CD36, CD68, COLEC12, MARCO) and regulatory T-cell genes (FOXP3) were higher in cHL. Importantly, PD-L1 and CD155 (respective ligands for PD-1 and TIGIT) were expressed at the surface of NLPHL and cHL malignant B-cells. Multispectral immunofluorescent microscopy showed intratumoral TIGIT+CD4+ and PD-1+CD4+ T-cells were markedly increased in NLPHL versus cHL and localised within NLPHL follicles. Expanded populations of intratumoral CD4+ T-cell clones were predominantly PD-1+ and frequently also TIGIT+. Multi-parameter flow cytometry and dimensionality reduction was used to establish the distribution of immune checkpoints within circulating T-cell subsets. PD-1+TIGIT+CD4+ T-cells were raised in circulating Treg, TH1 and TH2 subsets in NLPHL versus cHL, and PD-1+TIGIT+ TH2 T-cells displayed raised levels of the exhaustion marker EOMES, collectively indicating systemic T-cell dysfunction. To functionally demonstrate the utility of ICB to stimulate T-cells, an assay using cHL and/or NLPHL cell-lines co-cultured with a genetically engineered effector T-cell-line was developed. This showed that TIGIT/PD-1 dual-blockade was more effective than mono-blockade in inducing NLPHL and cHL tumor-directed CD4+ T-cell activation. Overall, our results indicate that immune-evasion mechanisms in NLPHL are distinct to those operative in cHL, with markedly greater T-cell, PD-1 and TIGIT dysregulation. PD-1 and/or TIGIT blockade warrants evaluation in NLPHL. Citation Format: Jay Gunawardana, Soi C. Law, Muhammed B. Sabdia, Karolina Bednarska, Sandra Brosda, Andreea Zaharia, Hennes Tsang, Lilia M. de Long, Melinda Burgess, Dipti Talaulikar, Justina N. Lee, Emily Jude, Eliza A. Hawkes, Sanjiv Jain, Karthik Nath, Clare Gould, Fiona Swain, Joshua W. D. Tobin, Colm Keane, Simone Birch, Mohamed Shanavas, Cameron Snell, Maher K. Gandhi. The immune checkpoints TIGIT and PD-1 are markedly upregulated in NLPHL compared to classical Hodgkin Lymphoma [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A17.

Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) comprises 5% of all Hodgkin lymphomas (HL). Its biology remains poorly characterized. Like classical HL (cHL), it contains minimal malignant cells embedded within a T cell rich intra-tumoral microenvironment (TME). Unlike cHL, it can transform to diffuse large B cell lymphoma (DLBCL). Immune-checkpoint blockade is effective in cHL but has minimal activity in DLBCL. No data is currently available regarding the potential to reactivate host anti-tumoral activity via immune-checkpoint blockade in NLPHL.

Follicular lymphoma (FL) is the most common indolent non-Hodgkin lymphoma. Twenty to twenty-five percent of FL patients have progression of disease within 24 months. These patients may benefit from immunotherapy if intact antigen presentation is present. Molecular mechanisms impairing major histocompatibility complex class-I (MHC-I) in FL remain undefined. Here, by sequencing of 172 FL tumours, we found the MHC-I transactivator NLRC5 was the most frequent gene abnormality in the MHC-I pathway. Pyrosequencing showed that epigenetic silencing of the NLRC5 promoter occurred in 30% of cases and was mutually exclusive to copy number loss (CNL) in NLRC5 (∼6% of cases). Hypermethylation and CNLs ("NLRC5 aberrant") had reduced NLRC5 gene expression compared to wild-type (WT) cases. By NanoString, there was reduced gene expression of the MHC-I pathway in aberrant tissues, including immunoproteasome components (PSMB8 and PSMB9), peptide transporters of antigen processing (TAP1), and MHC-I (HLA-A), compared to WT. By immunofluorescent microscopy, fewer NLRC5 protein-expressing malignant B-cells were observed in NLRC5 aberrant tissue sections compared to NLRC5 WT (P < .01). Consistent with a pivotal role in the activation of CD8+ T-cells, both CD8 and CD137 strongly correlated with NLRC5 expression (both r > 0.7; P < .0001). Further studies are required to determine whether patients with aberrant NLRC5 have a diminished response to immunotherapy.

Blockade of the PD-1 axis has modest efficacy in diffuse large B-cell lymphoma (DLBCL), but data regarding LAG3 are sparse. The impact of LAG3 digital gene expression was tested in 309 patients with DLBCL treated with standard chemoimmunotherapy. Cellular distribution of LAG3 protein was determined by immunohistochemistry and flow cytometry. In tumor-infiltrating lymphocytes (TILs), LAG3 expression was highest on CD4+ regulatory T cells (Tregs) and was also highly expressed on CD8+ T cells compared with CD4+ non-Tregs (both P = .008). LAG3high TILs were enriched in PD-1 and TIM-3. LAG3 was also expressed on a proportion of malignant B cells, and these patients had significantly higher LAG3 messenger RNA in their biopsies (P = .03). LAG3high gene expression was associated with inferior survival in discovery/validation cohorts, independent of cell of origin and the international prognostic index. Patients who were PD-L1high were fivefold more likely to be LAG3high (P < .0001). Patients who were LAG3high/PD-L1high had an inferior progression-free survival (P = .011) and overall survival (P = .005) compared with patients who were LAG3low/PD-L1high. Digital spatial protein analysis confirms LAG3 expression on T cells and, surprisingly, tumor-associated macrophages (TAMs) at higher levels than found on CD20+ B cells in the tumor microenvironment. LAG3 is frequently expressed on CD4+ Tregs and CD8+ TILs, typically with other immune checkpoints, and is also present in a proportion of malignant B cells in DLBCL and in areas enriched for TAMs. LAG3high expression is associated with poor outcome independent of conventional prognosticators.

PURPOSE Understanding the immunobiology of the 15% to 30% of patients with follicular lymphoma (FL) who experience progression of disease within 24 months (POD24) remains a priority. Solid tumors with low levels of intratumoral immune infiltration have inferior outcomes. It is unknown whether a similar relationship exists between POD24 in FL. PATIENTS AND METHODS Digital gene expression using a custom code set—five immune effector, six immune checkpoint, one macrophage molecules—was applied to a discovery cohort of patients with early- and advanced-stage FL (n = 132). T-cell receptor repertoire analysis, flow cytometry, multispectral immunofluorescence, and next-generation sequencing were performed. The immune infiltration profile was validated in two independent cohorts of patients with advanced-stage FL requiring systemic treatment (n = 138, rituximab plus cyclophosphamide, vincristine, prednisone; n = 45, rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone), with the latter selected to permit comparison of patients experiencing a POD24 event with those having no progression at 5 years or more. RESULTS Immune molecules showed distinct clustering, characterized by either high or low expression regardless of categorization as an immune effector, immune checkpoint, or macrophage molecule. Low programmed death-ligand 2 (PD-L2) was the most sensitive/specific marker to segregate patients with adverse outcomes; therefore, PD-L2 expression was chosen to distinguish immune infiltrationHI (ie, high PD-L2) FL biopsies from immune infiltrationLO (ie, low PD-L2) tumors. Immune infiltrationHI tissues were highly infiltrated with macrophages and expanded populations of T-cell clones. Of note, the immune infiltrationLO subset of patients with FL was enriched for POD24 events (odds ratio [OR], 4.32; c-statistic, 0.81; P = .001), validated in the independent cohorts (rituximab plus cyclophosphamide, vincristine, prednisone: OR, 2.95; c-statistic, 0.75; P = .011; and rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone: OR, 7.09; c-statistic, 0.88; P = .011). Mutations were equally proportioned across tissues, which indicated that degree of immune infiltration is capturing aspects of FL biology distinct from its mutational profile. CONCLUSION Assessment of immune-infiltration by PD-L2 expression is a promising tool with which to help identify patients who are at risk for POD24.

In advanced-stage diffuse large B-cell lymphoma (DLBCL), the presence of an activated B-cell phenotype or a non-germinal center (GCB) phenotype, coexpression of MYC and BCL2 by immunohistochemistry, and the cooccurrence of MYC and BCL2 or BCL6 rearrangements are associated with inferior outcomes. It is unclear whether these variables remain prognostic in stage I/II patients. In this retrospective study, we evaluated the prognostic impact of cell of origin (COO), as well as dual-expressor (DE) status and molecular double-hit (DH) status, in stage I/II DLBCL by positron emission tomography with computed tomography (PET-CT). A total of 211 patients treated with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone)-like regimens, with or without radiotherapy, was included. The median follow-up in the entire cohort was 4 years (range, 0.4-9.4), with estimated 4-year progression-free survival (PFS) and overall survival (OS) rates of 85% (95% confidence interval [CI], 79-89) and 88% (95% CI, 83-92), respectively. By univariable analysis, DE (PFS: hazard ratio [HR], 1.27; 95% CI, 0.58-2.81, P = .55 and OS: HR, 1.40; 95% CI, 0.60-3.30; P = .44), DH (PFS: HR, 1.21; 95% CI, 0.27-5.31; P = .80 and OS: HR, 0.61; 95% CI, 0.08-4.73; P = .64), and non-GCB status (PFS: HR, 1.59; 95% CI, 0.83-3.03; P= .16 and OS: HR, 1.80; 95% CI, 0.89-3.67; P = .10) were associated with poorer outcomes. In patients with PET-CT-defined stage I/II DLBCL treated with R-CHOP-like therapy, with or without radiation, COO and DE and DH status were not significantly associated with inferior PFS or OS.

Introduction Interactions between tumor cells and the immune system play a critical role in regulating tumor development. Immune-based therapies have shown variable responses in diffuse large B-cell lymphoma (DLBCL) which suggests that the immune cell composition of the tumor microenvironment (TME) influences response to these agents. However, the key determinants of the immune TME are poorly understood. We have recently shown that indolent lymphomas can be stratified as immunologically 'hot' or 'cold' (Tobin et al J. Clin Oncol, in press) and sought to test for this in DLBCL. Also, given that beta-2-microglobulin (B2M) has a key role in antigen presentation and its loss is a frequent immune evasion mechanism in DLBCL, we determined the effect of B2M expression on the nature and magnitude of immune infiltration in the tumor microenvironment of DLBCL. Methods Ninety-seven de novo systemic DLBCL FFPE biopsies underwent targeted exon re-sequencing of B2M (Illumina) in addition to quantitative gene expression of Β2M, immune effector (CD4, CD8, CD56, CD137), immunosuppressive macrophage markers (CD68, CD163) and immune checkpoints (TIM3, LAG3, PD1 and PDL1) (Nanostring Technologies). B2M promoter methylation by mass array, immunohistochemistry for the above markers and high throughput T-cell receptor β sequencing (Adaptive Biotechnologies) were performed on a subset of cases. Genomic findings were validated in a whole exome and transcriptome cohort of approximately 1000 DLBCL samples (Reddy et al Cell 2017). Results Β2MMut were detected in 14/97 (14.4%) samples and had lower Β2M gene expression compared to Β2MWT (p = 0.0094) and all of these showed B2M protein loss. However, 29/40 (72%) of B2MWT samples tested also had B2M protein loss. There was no differential methylation of B2M promoter regions observed compared to lymph node controls. Results indicate that mechanisms other than mutation and methylation status contribute to loss of B2M surface expression and that a more comprehensive assessment of B2M expression within tumor tissues is achieved by B2M digital gene quantification. Consistent with this, there were no significant differences in expression of intra-tumoral immune markers between B2MMut and B2MWT tissues, whereas gene expression of B2M was significantly associated and positively correlated with the gene expression of CD4, CD8, CD56, CD137, CD68, CD163, PD1, PDL1, LAG3 and TIM3 (all p <0.01) and with the protein expression of CD8, CD56, CD137, PDL1 and LAG3 (all p <0.01), irrespective of their classification as an immune-effector, immune-checkpoint or macrophage markers. These observations are consistent with a co-ordinately regulated immune response, indicating an adaptive immune-checkpoint response to regulate immune-effector activation. In keeping with this, the housekeeper genes did not correlate with immune gene expression indicating that high or low co-ordinate expression of immune genes was not reflecting tissue RNA quality or quantity (Fig 1). Next, we tested the discovery cohort for relationships with the TCR repertoire. High B2M gene expression was significantly associated with reduced TCR diversity (p = 0.0101) compared to low B2M gene expression, suggesting that clonal T cell expansions are more likely with intact antigen presentation. The validation cohort also demonstrated that B2M gene expression correlated with immune cell infiltration and additionally showed that B2M positively correlated with the gene expression of HLA Class I//II molecules and a range of regulatory, transport and assembly molecules involved in the antigen presentation machinery pathway. However, no differential survival benefit was observed in patients with high versus low B2M. Conclusions In summary, digital gene expression is a robust measure of B2M quantification in the TME. Our data show that high B2M gene expression reflects an immunologically active or 'hot' tumor microenvironment in DLBCL characterised by higher levels of immune cell infiltration. These findings indicate that B2M gene expression level could be used as a biomarker of an active intra-tumoral immune response in DLBCL. Further studies are required to determine if B2M gene expression may have a role in stratifying the selection of patients in whom immune-based therapies are more likely to be effective. Disclosures Gould: NovoNordisk: Other: Travel funding - domestic flights to attend education, May 2018. Keane:MSD: Consultancy; BMS: Research Funding; Celgene: Consultancy; Gilead: Consultancy; Roche: Consultancy, Other: Travel Grant. Hertzberg:Takeda: Consultancy, Honoraria; MSD: Consultancy; Roche: Consultancy, Honoraria. Gandhi:Gilead: Honoraria, Research Funding; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Other: Travel Support; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding; Merck: Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria.

Objective Epstein-Barr virus-positive diffuse large B-cell lymphoma (EBV-pos DLBCL) is a recently identified entity. Data regarding outcome to frontline immuno-chemotherapy are conflicting. Although the prognostic impact of the tumour microenvironment (TME) in EBV-neg DLBCL is well-established, it remains untested whether the TME influences survival in EBV-pos DLBCL. There are no data with new digital gene expression technologies that simultaneously interrogate the virus, B cells and the tumour microenvironment (TME). Methods We used the NanoString (TM) platform in a population-based cohort of 433 patients to establish if the technology could detect EBV in the tumour biopsies and to investigate the influence that EBV has on the complex tumour microenvironment of DLBCL. Results Incidence of EBV-pos DLBCL was 6.9% with 5-year survival of 65% vs 82% in EBV-neg DLBCL (P = 0.018). EBV-pos tissues had similar expression of T-cell genes compared to EBV-neg DLBCL but higher levels of the antigen-presenting molecule B2M. This was countered by elevated PD-L1, PD-L2, LAG3 and TIM3 immune checkpoints and a higher CD163/CD68 "M2" macrophage score. Conclusion In EBV-pos DLBCL, the TME is immuno-tolerogenic and may explain the poor outcomes seen in this subtype of DLBCL.

In classical Hodgkin lymphoma (CHL) the tumor microenvironment (TME) is enriched in T cells that modulate antitumor immunity. PD1 blockade partially restores anti-tumoral T cell function, to induce impressive responses in a proportion of patients with relapsed/refractory CHL (Chen et al JCO 2017). Further characterisation of T cell immune evasion mechanisms in CHL will permit the rational development of enhanced immunotherapeutic strategies. Lymphocyte-activation gene 3 (LAG3) is a cell surface molecule known to be expressed on a subset of immune effector T cells and intratumoral regulatory T cells (Tregs) in solid-organ tumors, with combination PD1/LAG3 mAb blockade showing early promise (Ascierto et al 2017 JCO abst 9520). In contrast, data in haematological malignancies is limited, although it is known that LAG3+ T cells suppress anti-tumoral immunity in CHL and B-CLL (Gandhi et al Blood 2006; Shapiro et al Haematologica 2017). Interestingly, in B-CLL LAG3 is found on both T cells and malignant B cells. Whether Hodgkin Reed-Sternberg (HRS) cells express LAG3 is unknown.

A plethora of individual candidate biomarkers for predicting biochemical relapse in localized prostate cancer (PCa) have been proposed. Combined biomarkers may improve prognostication, and ensuring validation against more clinically relevant endpoints are required. The Australian PCa Research Centre NSW has contributed to numerous studies of molecular biomarkers associated with biochemical relapse. In the current study, these biomarkers were re‐analyzed for biochemical relapse, metastatic relapse and PCa death with extended follow‐up. Biomarkers of significance were then used to develop a combined prognostic model for clinical outcomes and validated in a large independent cohort. The discovery cohort (n = 324) was based on 12 biomarkers with a median follow‐up of 16 years. Seven biomarkers were significantly associated with biochemical relapse. Three biomarkers were associated with metastases: AZGP1, Ki67 and PML. Only AZGP1 was associated with PCa death. In their individual and combinational forms, AZGP1 and Ki67 as a dual BM signature was the most robust predictor of metastatic relapse (AUC 0.762). The AZPG1 and Ki67 signature was validated in an independent cohort of 347 PCa patients. The dual BM signature of AZGP1 and Ki67 predicted metastasis in the univariable (HR 7.2, 95% CI, 1.6–32; p = 0.01) and multivariable analysis (HR 5.4, 95% CI, 1.2–25; p = 0.03). The dual biomarker signature marginally improved risk prediction compared to AZGP1 alone (AUC 0.758 versus 0.738, p < 0.001). Our findings indicate that biochemical relapse is not an adequate surrogate for metastasis or PCa death. The dual biomarker signature of AZGP1 and Ki67 offers a small benefit in predicting metastasis over AZGP1 alone.

LAG3 is an immune checkpoint expressed on a variety of immune cells including a sub-population of ‘exhausted’ effector T cells and TREGs. Early-phase studies of anti-LAG3 mAb show promise in solid and haematological cancers. We have previously demonstrated LAG3 is enriched within the tumor microenvironment in Hodgkin Lymphoma (Gandhi et al. Blood 2006). Data in the aggressive B-cell lymphoma DLBCL is lacking.

Much focus has been on the interaction of programmed cell death ligand 1 (PD-L1) on malignant B cells with programmed cell death 1 (PD-1) on effector T cells in inhibiting antilymphoma immunity. We sought to establish the contribution of natural killer (NK) cells and inhibitory CD163+ monocytes/macrophages in Hodgkin lymphoma (cHL) and diffuse large B-cell lymphoma (DLBCL). Levels of PD-1 on NK cells were elevated in cHL relative to DLBCL. Notably, CD3-CD56hiCD16-ve NK cells had substantially higher PD-1 expression relative to CD3-CD56dimCD16+ cells and were expanded in blood and tissue, more marked in patients with cHL than patients with DLBCL. There was also a raised population of PD-L1-expressing CD163+ monocytes that was more marked in patients with cHL compared with patients with DLBCL. The phenotype of NK cells and monocytes reverted back to normal once therapy (ABVD [doxorubicin 25 mg/m2, bleomycin 10 000 IU/m2, vinblastine 6 mg/m2, dacarbazine 375 mg/m2, all given days 1 and 15, repeated every 28 days] or R-CHOP [rituximab 375 mg/m2, cyclophosphamide 750 mg/m2 IV, doxorubicin 50 mg/m2 IV, vincristine 1.4 mg/m2 (2 mg maximum) IV, prednisone 100 mg/day by mouth days 1-5, pegfilgrastim 6 mg subcutaneously day 4, on a 14-day cycle]) had commenced. Tumor-associated macrophages (TAMs) expressed high levels of PD-L1/PD-L2 within diseased lymph nodes. Consistent with this, CD163/PD-L1/PD-L2 gene expression was also elevated in cHL relative to DLBCL tissues. An in vitro functional model of TAM-like monocytes suppressed activation of PD-1hi NK cells, which was reversed by PD-1 blockade. In line with these findings, depletion of circulating monocytes from the blood of pretherapy patients with cHL and patients with DLBCL enhanced CD3-CD56hiCD16-ve NK-cell activation. We describe a hitherto unrecognized immune evasion strategy mediated via skewing toward an exhausted PD-1-enriched CD3-CD56hiCD16-ve NK-cell phenotype. In addition to direct inhibition of NK cells by the malignant B cell, suppression of NK cells can occur indirectly by PD-L1/PD-L2-expressing TAMs. The mechanism is more prominent in cHL than DLBCL, which may contribute to the clinical sensitivity of cHL to PD-1 blockade.

There is proven pre-clinical and clinical efficacy of mono or combinatorial immune strategies to boost host anti-lymphoma immunity, with classical Hodgkin Lymphoma (cHL) seen as the ‘poster child’. Approaches include blockade of immune-checkpoints on exhausted tumor-specific T-cells (via mAb blockade of PD-1, TIM3, LAG3, TIGIT or their ligands), activation of T-cells via mAbs agonistic to CD137, and finally modulation of FOXP3, CTLA-4 and/or LAG3 regulatory T-cells (Tregs) or immunosuppressive tumor-associated macrophages (TAMs). In contrast, studies characterizing the circulating and intra-tumoral microenvironment (TME) of the distinct but rare CD20+ Hodgkin Lymphoma entity (5-8% of HL), Nodular Lymphocyte Predominant Hodgkin Lymphoma (NLPHL), are minimal. Furthermore, to our knowledge no functional profiling studies comparing the host immunity of NLPHL with cHL has been performed.

Richter syndrome is the transformation of chronic lymphoid leukaemia (CLL)/small lymphocytic lymphoma (SLL) to an aggressive lymphoma. This most commonly involves a diffuse large B cell lymphoma and less commonly classical Hodgkin lymphoma. Other rare entities have been reported including prolymphocytic lymphoma, dendritic cell sarcoma and plasmablastic lymphoma.