PD-1 expression on the surface of peripheral blood CD4+ T cell and its association with the prognosis of patients with diffuse large B-cell lymphoma

Novel Targets and Advanced Therapies in Diffuse Large B Cell Lymphomas

Since the introduction of rituximab in the late 1990s, significant progress has been made in advancing targeted therapies for B cell lymphomas, improving patients' chance of being cured and clinicians' therapeutic armamentarium. A better understanding of disease biology and pathogenic pathways, coupled with refinements in immunophenotypic and molecular diagnostics, have been instrumental in these achievements. While traditional chemotherapy remains fundamental in most cases, concerns surrounding chemorefractoriness and cumulative toxicities, particularly the depletion of the hemopoietic reserve, underscore the imperative for personalized treatment approaches. Integrating targeted agents, notably monoclonal antibodies, alongside chemotherapy has yielded heightened response rates and prolonged survival. A notable paradigm shift is underway with innovative-targeted therapies replacing cytotoxic drugs, challenging conventional salvage strategies like stem cell transplantation. This review examines the landscape of emerging targets for lymphoma cells and explores innovative therapies for diffuse large B cell lymphoma (DLBCL). From Chimeric Antigen Receptor-T cells to more potent monoclonal antibodies, antibody-drug conjugates, bispecific antibodies, checkpoint inhibitors, and small molecules targeting intracellular pathways, each modality offers promising avenues for therapeutic advancement. This review aims to furnish insights into their potential implications for the future of DLBCL treatment strategies.

PD-L1 Is Involved in the Development of Non-Hodgkin's Lymphoma by Mediating Circulating Lymphocyte Apoptosis

Lymphocyte apoptosis plays a crucial role in tumor-induced immunosuppression. Programmed death ligand-1 (PD-L1) blocks lymphocyte activation via its receptor, PD-1. However, PD-L1/PD-1 expression and its role in enhancing immune suppression in non-Hodgkin lymphoma (NHL) have not been identified. The purpose of the study was to assess PD-L1/PD-1 expression in circulating lymphocytes in NHL and its role in immunosuppression. Twenty newly diagnosed NHL patients and twenty normal volunteers were enrolled in the study. PD-L1/PD-1 expression in circulating lymphocytes and the apoptosis of lymphocyte subsets were assessed using flow cytometry. The findings revealed that the PD-L1 expression in circulating CD3+, CD3+CD4+, CD3+CD8+, and CD20+ lymphocytes were dramatically upregulated in NHL patients (p < 0.001), whereas peripheral lymphocytes expressed low levels of PD-1. Compared with normal volunteers, a significant increase in lymphocyte apoptosis was revealed by annexin-V binding on T and B lymphocytes (p < 0.001). Peripheral lymphocytes expressing PD-L1 were four times more vulnerable to apoptosis than those expressing PD-1. Our findings imply that PD-L1 upregulation contributes to NHL development by promoting circulating lymphocyte apoptosis. This research adds to our understanding of the function of the PD-L1/PD-1 pathway in tumor evasion, establishing a novel therapeutic target in NHL. The results offer additional evidence for the immunomodulatory role of PD-L1 in circulating lymphocytes, providing a rationale for further investigations into immunological dysfunctions resulting from NHL. PD-L1+ lymphocytes could be employed as a biomarker to assess the effectiveness of immune systems and predict illness in patients with NHL.

Coexpression of PD-L1/PD-1 with CXCR3/CD36 and IL-19 Increase in Extranodal Lymphoma

Many studies have demonstrated that PD-L1/PD-1 signaling is an immune evasion mechanism in tumors. PD-L1/PD-1 coexpression with CXCR3/CD36 in peripheral lymphocytes in lymphoma still needs to be clarified. The current study investigated PD-L1/PD-1 coexpression with CXCR3/CD36 in circulating lymphocytes, serum IL-19 levels, and their correlation with clinical outcome and extranodal involvement in lymphoma. Subjects and Methods. The coexpression of PD-L1/PD-1 with CXCR3/CD36 on circulating lymphocytes was analyzed by flow cytometry in 78 lymphoma patients before and after therapy and in 50 healthy controls. The concentration levels of IL-19 in serum were assessed by an ELISA. Results. PD-L1 and PD-1 were expressed on circulating CXCR3+ and CD36+ lymphocytes in lymphoma and were significantly higher in patients with extranodal involvement than in lymphoma patients without extranodal involvement (P < 0.001). Elevated IL-19 levels were observed in lymphoma patients and increased significantly in extranodal involvement (P < 0.001). High percentages of PD-L1+CXCR3+ and PD-1+CXCR3+ lymphocytes were associated with high LDH levels, hepatomegaly, lymphedema, advanced tumor stage, and recurrence. Furthermore, patients with splenomegaly and generalized lymphadenopathy had high percentages of PD-L1+CXCR3+ lymphocytes. In addition, levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 were significantly associated with bone marrow, lung, and lymph vessel involvement. Further analysis revealed that high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes were associated with lung and bone marrow involvement. Patients with high levels of PD-L1/PD-1 coexpression with CXCR3 and IL-19 had inferior event-free survival (EFS) compared with that in lymphoma patients with low levels. EFS was decreased in patients with high percentages of PD-L1+CD36+ and PD-1+CD36+ lymphocytes. When using the receiver operating characteristic (ROC) curve, the superiority of IL-19 (area under the curve (AUC): 0.993) and PD-L1+CXCR3+% (AUC: 0.961) to PD-1+CXCR3+% (AUC: 0.805), PD-L1+CD36+% (AUC: 0.694), and PD-1+CD36+% (AUC 0.769) was evident in the diagnosis of extranodal involvement, identifying lymphoma patients with extranodal involvement from patients without extranodal involvement. Conclusions. Coexpression of PD-L1/PD-1 with CXCR3/CD36 in circulating lymphocytes and serum IL-19 levels contributes to poor prognosis and might be potential markers for extranodal involvement in lymphoma.

EMAP II Expression Is Increased on Peripheral Blood Cells from Non-Hodgkin Lymphoma

Tumor immune evasion is a lineament of cancer. Endothelial monocyte activating polypeptide-II (EMAP II) has been assumed to impact tumor immune escape significantly. EMAP II was first reported in the murine methylcholanthrene A-induced fibrosarcoma supernatant and identified as a tumor-derived cytokine. This study evaluated EMAP II expression in peripheral blood cells and its association with treatment outcome, lactate dehydrogenase (LDH) levels, and clinical criteria in non-Hodgkin's lymphoma (NHL) patients. EMAP II expression on different blood cells obtained from the peripheral blood of 80 NHL patients was evaluated by two-color flow cytometry. The study reported that EMAP II expression was significantly increased in peripheral blood cells in patients with NHL compared to normal volunteers (P < 0.001). Additionally, EMAP II expression levels on blood cells decreased in complete remission (CR) while they increased in relapse. This study showed coexpression of EMAP II and CD36 on peripheral lymphocytes in NHL patients but not in healthy controls (P < 0.001). EMAP II expression on blood cells was associated with increased serum LDH levels. Furthermore, the percentages of EMAP II+/CD36+ peripheral lymphocytes were significantly higher in relapse than in CR and healthy controls. Analyses revealed that higher percentages of EMAP II+CD36+ cells were positively correlated with hepatomegaly, splenomegaly, and an advanced (intermediate and high risk) NHL stage. The results assume that EMAP II might be involved in NHL development and pathogenesis.

Diagnostic Performance of PD-L1 versus PD-1 Expression in Circulating CD20 Cells in Diffuse Large B-Cell Lymphoma

This study aimed to investigate PD-L1 and PD-1 expression in circulating CD20+ cells in diffuse larger B-cell lymphoma (DLBCL) and to evaluate the predictive and diagnostic performance of PD-L1 versus PD-1 expression in circulating CD20+ cells in DLBCL. Percentages of CD20+, PD-L1+CD20+, and PD-1+CD20+ cells were measured by flow cytometry in 40 DLBCL blood samples and 19 healthy controls. The DLBCL patient group was subdivided into 20 newly diagnosed patients with no treatment yet and 20 patients that had finished six cycles of CHOP therapy. Percentages of PD-L1+CD20+ and PD-1+CD20+ cells were highly significantly increased in pre-therapy patients in comparison to healthy volunteers (p < 0.001). Meanwhile, a significant decrease in percentages of PD-L1+CD20+ and PD-1+CD20+ was observed in post-CHOP therapy patients in comparison to pre-therapy patients (p < 0.001). PD-L1+CD20+ cells were significantly decreased in post-therapy patients when compared to normal controls (p < 0.001), while not for PD-1+CD20+ cells. A strong significant positive correlation between percentages of PD-L1+CD20+ and PD-1+CD20+ was detected in DLBCL patients (p < 0.001). In the pre-therapy group, high PD-L1+CD20+ and PD-1+CD20+ percentages were correlated with serum LDH levels (p = 0.021, p < 0.001). High percentages of PD-1+CD20+ were found in DLBCL patients with splenomegaly (p = 0.027). The results revealed that patients with advanced tumor stages, poor ECOG performance, and non-GCB DLBCL type had increased percentages of PD-L1+CD20+ and PD-1+CD20+ cells. Moreover, PD-L1+CD20+ % and PD-1+CD20+ % were significantly increased in DLBCL patients with bone marrow involvement or B symptoms. The superiority of PD-L1+CD20+ over PD-1+CD20+ was more profound in DLBCL prediction [AUC: 1.0] and in discriminating newly diagnosed patients [AUC: 1.0]. The findings suggest that increased PD-L1/PD-1 expression in peripheral CD20 cells may serve as a companion diagnostic marker for DLBCL. Moreover, percentages of PD-L1+CD20+ cells have better diagnostic performance with higher sensitivity and specificity than PD-1+CD20+ %.

Prognostic implication of CTLA-4, PD-1, and PD-L1 expression in aggressive adult T-cell leukemia-lymphoma

The prognosis of patients with aggressive adult T cell leukemia-lymphoma (ATLL) is dismal even with intensive chemotherapy. Allogeneic hematopoietic stem cell transplantation (HSCT) is a promising option for patients with aggressive ATLL, but the posttransplant outcome remains unsatisfactory. Hence, to further improve clinical outcomes, novel therapeutic approaches are needed. The clinical significance of immune checkpoint protein expression has not been well-established in aggressive ATLL. This study aims to identify the association between the expression profile of immune checkpoint proteins on ATLL cells and clinical outcomes. This retrospective study cohort included 65 patients with aggressive ATLL diagnosed between 2001 and 2015 at the National Cancer Center Hospital, Tokyo, Japan. Formalin-fixed paraffin-embedded tissue was used to immunohistochemically determine the expression of immune checkpoint proteins and assess the impact of expression profile on the probability of overall survival from diagnosis or HSCT. The current analysis shows that cytotoxic T lymphocyte antigen-4 (CTLA-4), programmed death-1 (PD-1), and programmed death-ligand 1 (PD-L1) expressions were adverse prognostic factors in patients with aggressive ATLL. Experiments that assess the efficacy of immune checkpoint inhibitors are warranted to alleviate the adverse impacts associated with negative immune checkpoints.

Immune normalization strategy against suboptimal health status: safe and efficacious therapy using mixed-natural killer cells

"Immune normalization" has emerged as a new paradigm in immunotherapy, which is proposed in cancer patients instead of conventional "immune-enhancement" therapy. Immune normalization may also be implemented in cancer prevention of "sub-healthy" individuals. We established in vitro cultured mixed-natural killer (NKM) cells to achieve immune normalization. The in vitro cytotoxicity of NKM cells was tenfold higher than that of peripheral blood mononuclear cells (PBMCs). The cytotoxicity of NKM cells was negatively correlated with the proportion of T-helper cells (cluster of differentiation: CD3+CD4+ T), and positively correlated with the proportion of NK cells (especially CD56^brightCD16^bright NK cells). Then, we defined "sub-healthy individuals" after measuring Programmed cell death protein-1 (PD-1) expression in PBMCs from 95 donors aged > 50 years. Furthermore, we evaluated the potential clinical application of NKM-cell therapy in 11 patients with malignant lymphoma, one patient with pancreatic cancer, and four sub-healthy individuals. NKM-cell therapy elicited good tolerance and side-effects were not found. In sub-healthy individuals, the proportion of CD3⁺PD-1⁺ T cells and CD3⁺CD8⁺PD-1⁺ T cells was reduced significantly after NKM-cell treatment. We demonstrated that a new method using NKM cells was safe and efficacious as adjuvant treatment for cancer patients as well as therapy for sub-healthy individuals. Normalization of the peripheral immune system through NKM-cell therapy could expand its scope of application in different disorders.

Circulating myeloid-derived suppressor cells and regulatory T cells as immunological biomarkers in refractory/relapsed diffuse large B-cell lymphoma: translational results from the R2-GDP-GOTEL trial

Background

The search for immunological markers with ability of predicting clinical outcome is a priority in lymphomas, and in cancer in general. It is well known that some immunomodulatory cells, such as myeloid derived suppressor cells (MDSCs) or regulatory T cells (Tregs), are recruited by tumors, jeopardizing antitumor immunosurveillance. In this work, we have studied blood levels of these immunosuppressive cells in patients with relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL), prior to and along the course of the experimental rituximab, gemcitabine, dexamethasone, and cisplatin (R2-GDP) schedule, as a translational substudy of the R2-GDP-GOTEL trial (EudraCT Number: 2014-001620-29), which included lenalidomide as an immunomodulator.

Methods

Blood samples were taken before treatment, at cycle 3 and end of induction. Samples were analyzed by flow cytometry. Non-parametric tests were used. Mann-Whitney U test was used to compare basal cells distributions, and Wilcoxon test was considered to compare cells distribution at different times. Spearman test was performed to measure the degree of association between cell populations.

Results

In this study, MDSC and Treg circulating concentration was found increased in all patients compared with a healthy control group and decreased after treatment only in patients with longest overall survival (>24 months), reaching the levels of the healthy group. Likewise, the number of inhibited T lymphocytes expressing Programmed Death-1 (PD-1) were increased in peripheral blood from patients and decreased on the treatment, whereas activated T lymphocytes increased after therapy in those with better overall survival.

Conclusions

In conclusion, blood concentration of MDSCs and Treg cells may be good prognostic markers for overall survival after 2 years in R/R DLBCL. These results point to a possible role of these elements in the immunosuppression of these patients, as assessed by the circulating activated and inhibited T lymphocytes, and therefore, they may be considered as therapeutic targets in DLBCL.

Functional characterization of PD1+TIM3+ tumor-infiltrating T cells in DLBCL and effects of PD1 or TIM3 blockade

In diffuse large B-cell lymphoma (DLBCL), tumor-infiltrating T lymphocytes (TILs) are involved in therapeutic responses. However, tumor-specific TILs can be dysfunctional, with impaired effector functions. Various mechanisms are involved in this exhaustion, and the increased expression of programmed cell death receptor 1 (PD1) and TIM3 on dysfunctional cells suggests their involvement. However, conflicting data have been published regarding their expression or coexpression in DLBCL. We evaluated the presence and phenotype of CD4+ and CD8+ TILs in freshly collected tumor tissues in DLBCL and compared the results with those in follicular lymphoma, classical Hodgkin lymphoma, and nonmalignant reactive lymphadenopathy. We found that TILs expressing both PD1 and TIM3 were expanded in DLBCL, particularly in the activated B cell-like subgroup. Isolated PD1+TIM3+ TILs exhibited a transcriptomic signature related to T-cell exhaustion associated with a reduction in cytokine production, both compromising the antitumor immune response. However, these cells expressed high levels of cytotoxic molecules. In line with this, stimulated PD1+TIM3+ TILs from DLBCL patients exhibited reduced proliferation and impaired secretion of interferon-γ, but these functions were restored by the blockade of PD1 or TIM3. In summary, the PD1+TIM3+ TIL population is expanded and exhausted in DLBCL but can be reinvigorated with appropriate therapies.

Soluble PD-1 but Not PD-L1 Levels Predict Poor Outcome in Patients with High-Risk Diffuse Large B-Cell Lymphoma

Simple Summary

Soluble forms of checkpoint protein PD-1 and its ligand PD-L1 can be measured from circulation, but their source, function, and clinical impact in cancer remain incompletely understood. In this study, we used serum samples collected during a conduction of a prospective immunochemotherapy trial in patients with high-risk diffuse large B-cell lymphoma (DLBCL) and assessed their clinical significance. Our results demonstrate that sPD-1 levels in the peripheral blood at the time of diagnosis correlate with the quantities of tumor infiltrating PD1+ T cells and translate to inferior survival. To our knowledge, this is the first study to identify sPD-1 as a prognostic factor, providing interesting perspectives on future clinical trials in DLBCL, including patients’ stratification associated with checkpoint blockade.

Abstract

Interaction of checkpoint receptor programmed death 1 (PD-1) with its ligand 1 (PD-L1) downregulates T cell effector functions and thereby leads to tumor immune escape. Here, we aimed to determine the clinical significance of soluble PD-1 (sPD-1) and soluble PD-L1 (sPD-L1) in patients with diffuse large B-cell lymphoma (DLBCL). We included 121 high-risk DLBCL patients treated in the Nordic NLG-LBC-05 trial with dose-dense immunochemotherapy. sPD-1 and sPD-L1 levels were measured from serum samples collected prior to treatment, after three immunochemotherapy courses, and at the end of therapy. sPD-1 and sPD-L1 levels were the highest in pretreatment samples, declining after three courses, and remaining low post-treatment. Pretreatment sPD-1 levels correlated with the quantities of PD1+ T cells in tumor tissue and translated to inferior survival, while no correlation was observed between sPD-L1 levels and outcome. The relative risk of death was 2.9-fold (95% CI 1.12–7.75, p = 0.028) and the risk of progression was 2.8-fold (95% CI 1.16–6.56, p = 0.021) in patients with high pretreatment sPD-1 levels compared to those with low levels. In conclusion, pretreatment sPD-1 level is a predictor of poor outcome after dose-dense immunochemotherapy and may be helpful in further improving molecular risk profiles in DLBCL.

Activating the Antitumor Immune Response in Non-Hodgkin Lymphoma Using Immune Checkpoint Inhibitors

Non-Hodgkin lymphomas comprise a heterogenous group of disorders which differ in biology. Although response rates are high in some groups, relapsed disease can be difficult to treat, and newer approaches are needed for this patient population. It is increasingly apparent that the immune system plays a significant role in the propagation and survival of malignant cells. Immune checkpoint blocking agents augment cytotoxic activity of the adaptive and innate immune systems and enhance tumor cell killing. Anti-PD-1 and anti-CTLA-4 antibodies have been tested as both single agents and combination therapy. Although success rates with anti-PD-1 antibodies are high in patients with Hodgkin lymphoma, the results are yet to be replicated in those with non-Hodgkin lymphomas. Some lymphoma histologies, such as primary mediastinal B cell lymphoma (PMBL), central nervous system, and testicular lymphomas and gray zone lymphoma, respond favorably to PD-1 blockade, but the response rates in most lymphoma subtypes are low. Other agents including those targeting the adaptive immune system such as TIM-3, TIGIT, and BTLA and innate immune system such as CD47 and KIR are therefore in trials to test alternative ways to activate the immune system. Patient selection based on tumor biology is likely to be a determining factor in treatment response in patients, and further research exploring optimal patient populations, newer targets, and combination therapy as well as identifying biomarkers is needed.

Prognostic and clinicopathological significance of PD-1/PD-L1 expression in the tumor microenvironment and neoplastic cells for lymphoma

BACKGROUND

Recently, unprecedented clinical efficacy was observed during treatment of many solid tumors because of the introduction of programmed cell death 1 (PD-1)/programmed cell death 1 ligand 1 (PD-L1) immune checkpoint inhibitors. Preliminary clinical data indicates that checkpoint inhibition also represents a promising therapeutic strategy for certain lymphoid malignancies. However, PD-1/PD-L1 expression levels on neoplastic cells and in the tumor microenvironment vary among subtypes and their prognostic implications remain uncertain.

MAIN BODY

Here, we review the clinicopathological significance of PD-1/PD-L1 expression in lymphomas. Increased infiltration of PD-1+ tumor-infiltrating lymphocytes (TILs) is a favorable prognostic factor in diffuse large B-cell lymphoma (DLBCL) but not in Hodgkin's lymphoma (HL). Higher numbers of PD-1+ TILs were observed in follicular lymphoma (FL) than in other subtypes of B-cell lymphoma; however, its prognostic significance remains controversial. Infiltration of PD-L1+ immune cells showed a trend toward better overall survival in nasal natural killer (NK)/T-cell lymphoma and adult T-cell leukemia/lymphoma, more likely to be classified as activated macrophages and dendritic cells in microenvironment but its biological effect is not clarified. Peripheral PD-1+ T cells could be detected in blood samples from DLBCL and chronic lymphocytic leukemia (CLL) and correlated with disease progression and poor prognosis. PD-1+ neoplastic T cells were more frequently observed in cutaneous T-cell lymphoma, including Sézary syndrome and mycosis fungoides, which may be involved in the progression of epithelial-derived T lymphoma. Studies on PD-L1 expression in neoplastic cells mostly focused on DLBCL. PD-L1+ neoplastic cells were observed only in a small subset of DLBCL, mainly associated with activated B cell (ABC) subtypes and Epstein-Barr virus (EBV) positivity; however, its prognostic role remains controversial. In either T or B lymphoma, elevated serum or plasma levels of soluble PD-L1 represent adverse prognostic factors. Notably, in clinical trials of classical HL, the frequency of 9p24.1 chromosome alterations increases the abundance of PD-1 ligand expression, appearing to predict responses to anti-PD-1/PD-L1 therapy. The cytogenetic alterations affecting chromosome 9p24.1 including the CIITA rearrangement were also frequently observed in certain specific subtypes of large B-cell lymphomas.

CONCLUSIONS

The clinical roles of PD-1/PD-L1 expression vary between subtypes of lymphoma. Future studies should delineate the prognostic and predictive roles of PD-1 and PD-L1 expression.

The Prognostic Roles of Pretreatment Circulating Tumor Cells, Circulating Cancer Stem-Like Cells, and Programmed Cell Death-1 Expression on Peripheral Lymphocytes in Patients with Initially Unresectable, Recurrent or Metastatic Head and Neck Cancer: An Exploratory Study of Three Biomarkers in One-time Blood Drawing

Circulating tumor cells (CTCs) and immune status are strongly related to cancer prognosis, although few studies have examined both factors. This prospective observational study (ClinicalTrials.gov: NCT02420600) evaluated whether CTCs, circulating cancer stem-like cells (cCSCs), and peripheral lymphocytes with/without Programmed cell death protein 1 (PD-1) expression were associated with prognosis among patients receiving palliative chemotherapy for initially unresectable, recurrent/metastatic head and neck squamous cell carcinoma (rmHNSCC). Thirty-four patients were enrolled between January 2015 and June 2016. Overall survival (OS) was associated with a higher CTC number (hazard ratio [HR]: 1.01, p = 0.0004) and cCSC ratio (HR: 29.903, p < 0.0001). Progression-free survival (PFS) was also associated with CTC number (HR: 1.013, p = 0.002) and cCSC ratio (HR: 10.92, p = 0.003). A CD8⁺ proportion of ≥ 17% was associated with improved OS (HR: 0.242, p = 0.004). A CD4: CD8 ratio of >1.2 was associated with poorer trend of PFS (HR: 2.12, p = 0.064). PD-1 expression was not associated with survival outcomes. Baseline CTCs, cCSC ratio, and CD8⁺ ratio may predict prognosis in rmHNSCC.

Circulating PD-1 (+) cells may participate in immune evasion in peripheral T-cell lymphoma and chidamide enhance antitumor activity of PD-1 (+) cells

Peripheral T‐cell lymphoma (PTCL) is a heterogeneous disease with poor outcomes. We intend to explore the role of circulating PD‐1 (+) cells in tumor immune evasion in PTCL patients and the mechanism of chidamide as a regulator of immune‐associated medicine on PD‐1 (+) cells. Gene expression profiling (GEP) was performed on circulating PD‐1 (+) cells from 22 PTCL patients and 13 healthy subjects, and circulating PD‐1 (−) cells from 2 PTCL patients. PD‐1 (+) cells were treated with chidamide, and the production IFN‐γ and cytotoxicity were analyzed. GEP were performed on circulating PD‐1 (+) cells from 2 PTCL patients treated with chidamide combined with chemotherapy and 1 patient treated with traditional chemotherapy. GEP showed that genes associated with innate immune response were abnormally expressed in PD‐1 (+) cells of PTCL patients compared with healthy subjects, meanwhile the expression of CTLA‐4 was significantly higher in PD‐1 (+) cells than that of PD‐1 (−) cells. In vitro study revealed decreased level of IFN‐γ secretion and impaired cytotoxic activity of PD‐1 (+) cells compared with PD‐1 (−) cells, while chidamide could recover the deficiencies and upregulate adaptive immune‐associated genes in PD‐1 (+) cells of PTCL patients. Our research indicated that PD‐1 (+) cells might have deficiencies in innate and adaptive immune response and chidamide may reverse the defects.

Disruption of CTLA-4 expression on peripheral blood CD8 + T cell enhances anti-tumor efficacy in bladder cancer

Activation of programmed death-1 (PD-1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) on T cells leads to T cell exhaustion and ultimately facilitates tumor progression. Recent success of using immune cell checkpoint inhibitors offers a great promise to treat various cancers, including bladder cancer. However, the expression pattern and therapeutic value of PD-1 and CTLA-4 in peripheral blood T cells remain largely unexplored. In this study, we presume that disruption of the potential dysregulated checkpoint molecules in peripheral blood T cells may improve the anti-tumor efficacy of cytotoxic T cells in bladder cancer. We showed that both PD-1 and CTLA-4 expression were specifically elevated on CD8 + T cells but not CD4 + T cells in peripheral blood of patients with bladder cancer compared with that in healthy donors. Notably, CTLA-4 expression was significantly higher in muscle-invasive bladder cancer (MIBC) and correlated with tumor size. By blocking CTLA-4 with anti-CTLA-4 antibody and CRISPR-Cas9-mediated CTLA-4 disruption, we revealed that CTLA-4-disrupted CTLs had enhanced cellular immune response and superior cytotoxicity to the CD80/CD86-positive bladder cancer cells in vitro. Moreover, the CTLA-4-disrupted CTLs exhibited a pronounced anti-tumor effect in vivo as demonstrated by prophylactic assay and therapeutic assay in the subcutaneous xenograft model. Collectively, our findings confirm improved therapeutic efficacy of CTLA-4-disrupted CTLs and provides the potential strategy for targeting immune checkpoints to enhance the promising immunotherapy.

CD103+ tumor-infiltrating lymphocytes predict favorable prognosis in patients with esophageal squamous cell carcinoma

As an indispensable factor in preventing the recirculation of tissue lymphocytes to the lymphatic and blood systems, the integrin CD103 has enabled the characterization of lymphocyte populations in non-lymphoid tissues and organs. However, the expression, distribution, and clinical significance of CD103⁺ tumor-infiltrating lymphocytes (TILs) in esophageal squamous cell carcinoma (ESCC) remain unclear. In the present study, we included tumor and adjacent non-tumor tissue specimens from 198 patients with ESCC who had undergone surgical resection. Immunohistochemistry and immunofluorescence were used to detect CD103⁺ TIL distribution, as well as the co-expression of CD103 and T cell markers and functional molecules. Kaplan-Meier analysis and the Cox proportional hazards model were used to estimate the prognostic value of CD103⁺ TILs. The results showed that CD103⁺ TILs were predominantly located in adjacent non-tumor tissues compared with tumor tissues (P < 0.0001). Immunofluorescence double staining revealed that CD8⁺ T cells, but not CD4⁺ T cells, comprised the majority of CD103-expressing cells. Most of these CD103-expressing cells co-expressed CTLA-4 and granzyme B rather than the exhaustion marker PD-1. High density of intratumoral CD103⁺ TIL is associated with longer overall survival (OS) and disease-free survival (DFS) in both the internal (OS, P = 0.0004 and DFS, P = 0.0002) and external (OS, P = 0.038 and DFS, P = 0.12) cohorts. Multivariate Cox analysis showed the density of CD103⁺ TILs was an independent positive prognostic factor for OS (hazards ratio [HR] = 0.406; P = 0.0003 in the internal cohort; HR = 0.328, P = 0.01, in the external cohort) and DFS (HR = 0.385; P = 0.0002 in the internal cohort; HR = 0.270, P = 0.003, in the external cohort). Our findings indicate that CD103⁺ TILs might play an important role in the tumor microenvironment, and intratumoral CD103⁺ TILs could serve as a promising prognostic marker in ESCC.

Evaluation of costimulatory molecules in dogs with B cell high grade lymphoma

B cell high grade lymphoma is the most common hematopoietic malignancy in dogs. Although the immune checkpoint molecules, programmed death-1 (PD-1) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4), and immune checkpoint inhibitors have been evaluated for the treatment of various human lymphoid malignancies, the expression of those molecules and their relationship with prognosis remain unknown in canine lymphoma. The objective of this study was to evaluate the expression of costimulatory molecules on peripheral blood lymphocytes and tumor infiltrating lymphocytes, in addition to associated ligand expression in the lymph nodes of patients with B cell multicentric high grade lymphoma. Eighteen patients diagnosed with B cell high grade lymphoma and nine healthy control dogs were enrolled. Flow cytometric analysis revealed that the expression of PD-1 on CD4+ peripheral and tumor infiltrating lymphocytes and CTLA-4 on CD4+ peripheral lymphocytes was significantly higher in the lymphoma group than in the control group. The expression level of CD80 mRNA was significantly lower in the lymphoma group than in the control group. In contrast, there were no significant differences in PD-L1, PD-L2, and CD86 expression between the groups. Dogs with CTLA-4 levels below the cutoff values, which were determined based on receiver operating characteristic curves, on peripheral CD4+, CD8+, and tumor infiltrating CD4+ lymphocytes had significantly longer survival than dogs with values above the cutoff. Although it is uncertain whether the expression of immune checkpoint molecules affect the biological behavior of canine lymphoma, one possible explanation is that PD-1 and CTLA-4 might be associated with the suppression of antitumor immunity in dogs with B cell high grade lymphoma, particularly through CD4+ T cells.

Biomarkers for checkpoint inhibition in hematologic malignancies

In the past few years we have seen remarkable paradigm shifts in the treatment of many solid tumors due to the introduction of inhibitors targeting immune checkpoints such as PD-1/PD-L1 and CTLA-4. Recent results indicate that checkpoint inhibition also represents a very promising approach for certain types of hematologic malignancies. Unfortunately, treatment with checkpoint inhibitors is also associated with substantial toxicities and high costs and only a subset of patients appears to derive clinical benefit from these treatments. This demonstrates the urgent need for biomarkers for the identification of patient populations that are likely to respond to this type of therapy and/or have fewer side effects. Here, we have reviewed available information on the prognostic and predictive value of biomarkers for anti-CTLA-4 and anti-PD-1/PD-L1 as the most commonly used checkpoint inhibitors. There are currently no reliable biomarkers capable of predicting responses to anti-CTLA-4 agents, such as ipilimumab, in hematologic malignancies. Certain polymorphisms in the CTLA-4 gene, however, seem to have an impact on the patients' outcome, especially in the case of chronic lymphocytic leukemia (CLL). There is now sufficient data supporting PD-L1 expression levels in the tumor tissue as an independent prognostic factor in B cell lymphomas such as diffuse large B-cell lymphoma (DLBCL). Overexpression of PD-L1 in the tumor tissue and elevated serum levels of soluble PD-L1 may also represent adverse prognostic factors in certain subtypes of T cell lymphomas. Finally, expression levels of PD-L1 also seem to predict responses to anti-PD-1/PD-L1 approaches in patients with Hodgkin lymphoma. Future studies will have to further delineate the prognostic/predictive role of PD-L1 expression as a biomarker in hematologic malignancies and may be able to identify confounding variables, which will hopefully to some extent be generalizable to other types of anti-tumor immunotherapies.

Mechanisms of PD-1/PD-L1 expression and prognostic relevance in non-Hodgkin lymphoma: a summary of immunohistochemical studies

Immune checkpoint blockade therapeutics, notably antibodies targeting the programmed death 1 (PD-1) receptor and its PD-L1 and PD-L2 ligands, are currently revolutionizing the treatment of cancer. For a sizeable fraction of patients with melanoma, lung, kidney and several other solid cancers, monoclonal antibodies that neutralize the interactions of the PD-1/PD-L1 complex allow the reconstitution of long-lasting antitumor immunity. In hematological malignancies this novel therapeutic strategy is far less documented, although promising clinical responses have been seen in refractory and relapsed Hodgkin lymphoma patients. This review describes our current knowledge of PD-1 and PD-L1 expression, as reported by immunohistochemical staining in both non-Hodgkin lymphoma cells and their surrounding immune cells. Here, we discuss the multiple intrinsic and extrinsic mechanisms by which both T and B cell lymphomas up-regulate the PD-1/PD-L1 axis, and review current knowledge about the prognostic significance of its immunohistochemical detection. This body of literature establishes the cell surface expression of PD-1/PD-L1 as a critical determinant for the identification of non-Hodgkin lymphoma patients eligible for immune checkpoint blockade therapies.

PD-1 expression and clinical PD-1 blockade in B-cell lymphomas

Programmed cell death protein 1 (PD-1) blockade targeting the PD-1 immune checkpoint has demonstrated unprecedented clinical efficacy in the treatment of advanced cancers including hematologic malignancies. This article reviews the landscape of PD-1/programmed death-ligand 1 (PD-L1) expression and current PD-1 blockade immunotherapy trials in B-cell lymphomas. Most notably, in relapsed/refractory classical Hodgkin lymphoma, which frequently has increased PD-1+ tumor-infiltrating T cells, 9p24.1 genetic alteration, and high PD-L1 expression, anti-PD-1 monotherapy has demonstrated remarkable objective response rates (ORRs) of 65% to 87% and durable disease control in phase 1/2 clinical trials. The median duration of response was 16 months in a phase 2 trial. PD-1 blockade has also shown promise in a phase 1 trial of nivolumab in relapsed/refractory B-cell non-Hodgkin lymphomas, including follicular lymphoma, which often displays abundant PD-1 expression on intratumoral T cells, and diffuse large B-cell lymphoma, which variably expresses PD-1 and PD-L1. In primary mediastinal large B-cell lymphoma, which frequently has 9p24.1 alterations, the ORR was 35% in a phase 2 trial of pembrolizumab. In contrast, the ORR with pembrolizumab was 0% in relapsed chronic lymphocytic leukemia (CLL) and 44% in CLL with Richter transformation in a phase 2 trial. T cells from CLL patients have elevated PD-1 expression; CLL PD-1+ T cells can exhibit a pseudo-exhaustion or a replicative senescence phenotype. PD-1 expression was also found in marginal zone lymphoma but not in mantle cell lymphoma, although currently anti-PD-1 clinical trial data are not available. Mechanisms and predictive biomarkers for PD-1 blockade immunotherapy, treatment-related adverse events, hyperprogression, and combination therapies are discussed in the context of B-cell lymphomas.

Prognostic value of programmed cell death protein 1 expression on CD8+ T lymphocytes in pancreatic cancer

Pancreatic cancer is one of the most aggressive malignancies and has a highly immunosuppressive tumour microenvironment. Immune checkpoint blockade has led to remarkable and durable objective responses in a number of malignancies and antibody-based strategies targeting programmed cell death protein 1 (PD-1) are showing promise where traditional modalities of surgery, radiotherapy, and chemotherapy have failed. In this study, we examined the clinical value of PD-1 protein expression by CD8+ peripheral T lymphocytes or tumour-infiltrating T lymphocytes (TILs) in pancreatic ductal adenocarcinoma (PDAC). Expression of PD-1 protein on CD8+ TILs correlated with overall survival and clinicopathological characteristics such as clinical stage, N classification, and M classification. Similar findings were observed for the expression of PD-1 protein on peripheral CD8+ T cells, whereas its expression on peripheral CD4+ T cells showed no significance. Comparison of the levels of PD-1 protein expressed by peripheral CD8+ T cells before and 4 weeks after surgery indicated that preoperative and postoperative status of peripheral PD-1 expression was unchanged. Our findings showed that PD-1 protein expressed by peripheral or tumour-infiltrated CD8+ T cells was a promising biomarker for diagnosis and prognosis in PDAC and might help guide future immunotherapies.

PD-1 expression on the surface of peripheral blood CD4+ T cell and its association with the prognosis of patients with diffuse large B-cell lymphoma

The aim of the study was to investigate the relationship between PD-1 expression on the surface of CD4+ T cells and prognosis of patients with diffuse large B-cell lymphoma (DLBCL). Sixty patients who were newly diagnosed with DLBCL and 39 healthy controls were enrolled. In CD4+ T cells of DLBCL patients, the median MFI of PD-1 were 541.5 (range: 348.25-758.75), significantly higher than 250 (range: 211-326) in healthy controls (P < 0.001). The ZAP70, PI3K, and NFAT mRNA expression levels of patients were 0.47, 0.47, and 0.62 times, respectively, of those of the healthy controls (P < 0.05). In patients with the percentage of PD-1 on CD4+ T cells ≥30.25%, their EFS and OS were significantly lower than patients with PD-1+ CD4+ T cells <30.25% (P < 0.05). The possible explanation is that high PD-1 expression on CD4+ cells of DLBCL patients may impair T-cell function and thus contribute to poor prognosis. There was no relationship between PD-1 surface expression on CD4+ T cells and PD-1 expression within the biopsy of tumor microenvironments from DLBCL patients.