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, CD3CD56CD16 NK cells had substantially higher PD-1 expression relative to CD3CD56CD16 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/m, bleomycin 10 000 IU/m, vinblastine 6 mg/m, dacarbazine 375 mg/m, all given days 1 and 15, repeated every 28 days] or R-CHOP [rituximab 375 mg/m, cyclophosphamide 750 mg/m IV, doxorubicin 50 mg/m IV, vincristine 1.4 mg/m (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-1 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 CD3CD56CD16 NK-cell activation. We describe a hitherto unrecognized immune evasion strategy mediated via skewing toward an exhausted PD-1-enriched CD3CD56CD16 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.

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.

Purpose: To investigate the relationship between the intratumoral T-cell receptor (TCR) repertoire and the tumor microenvironment (TME) in de novo diffuse large B-cell lymphoma (DLBCL) and the impact of TCR on survival.Experimental Design: We performed high-throughput unbiased TCRb sequencing on a population-based cohort of 92 patients with DLBCL treated with conventional (i.e., non-checkpoint blockade) frontline "R-CHOP" therapy. Key immune checkpoint genes within the TME were digitally quantified by nanoString. The primary endpoints were 4-year overall survival (OS) and progression-free survival (PFS).Results: The TCR repertoire within DLBCL nodes was abnormally narrow relative to non-diseased nodal tissues (P < 0.0001). In DLBCL, a highly dominant single T-cell clone was associated with inferior 4-year OS rate of 60.0% [95% confidence interval (CI), 31.7%-79.6%], compared with 79.8% in patients with a low dominant clone (95% CI, 66.7%-88.5%; P ¼ 0.005). A highly dominant clone also predicted inferior 4-year PFS rate of 46.6% (95% CI, 22.5%-76.6%) versus 72.6% (95% CI, 58.8%-82.4%, P ¼ 0.008) for a low dominant clone. In keeping, clonal expansions were most pronounced in the EBV þ DLBCL subtype that is known to express immunogenic viral antigens and is associated with particularly poor outcome. Increased T-cell diversity was associated with significantly elevated PD-1, PD-L1, and PD-L2 immune checkpoint molecules. Conclusions: Put together, these findings suggest that the TCR repertoire is a key determinant of the TME. Highly dominant T-cell clonal expansions within the TME are associated with poor outcome in DLBCL treated with conventional frontline therapy.

ObjectiveEpstein‐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).MethodsWe used the NanoString™ 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.ResultsIncidence 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.ConclusionIn EBV‐pos DLBCL, the TME is immuno‐tolerogenic and may explain the poor outcomes seen in this subtype of DLBCL.