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Purpose Sepsis-associated immunosuppression increases hospital-acquired infection and viral reactivation risk. A key underlying mechanism is programmed cell death protein-1 (PD-1)-mediated T-cell function impairment. This is one of the first clinical safety and pharmacokinetics (PK) assessments of the anti-PD-1 antibody nivolumab and its effect on immune biomarkers in sepsis. Methods Randomized, double-blind, parallel-group, Phase 1b study in 31 adults at 10 US hospital ICUs with sepsis diagnosed ≥ 24 h before study treatment, ≥ 1 organ dysfunction, and absolute lymphocyte count ≤ 1.1 × 10 3 cells/μL. Participants received one nivolumab dose [480 mg ( n  = 15) or 960 mg ( n  = 16)]; follow-up was 90 days. Primary endpoints were safety and PK parameters. Results Twelve deaths occurred [ n  = 6 per study arm; 40% (480 mg) and 37.5% (960 mg)]. Serious AEs occurred in eight participants [ n  = 1, 6.7% (480 mg); n  = 7, 43.8% (960 mg)]. AEs considered by the investigator to be possibly drug-related and immune-mediated occurred in five participants [ n  = 2, 13.3% (480 mg); n  = 3, 18.8% (960 mg)]. Mean ± SD terminal half-life was 14.7 ± 5.3 (480 mg) and 15.8 ± 7.9 (960 mg) days. All participants maintained > 90% receptor occupancy (RO) 28 days post-infusion. Median (Q1, Q3) mHLA-DR levels increased to 11,531 (6528, 19,495) and 11,449 (6225, 16,698) mAbs/cell in the 480- and 960-mg arms by day 14, respectively. Pro-inflammatory cytokine levels did not increase. Conclusions In this sepsis population, nivolumab administration did not result in unexpected safety findings or indicate any ‘cytokine storm’. The PK profile maintained RO > 90% for ≥ 28 days. Further efficacy and safety studies are warranted. Trial registration number (clinicaltrials.gov) NCT02960854.

Steven Rosenberg and colleagues report that PD-1 is a biomarker of CD8 + T cells in the blood that recognize mutated neoantigens in melanoma. Detection of lymphocytes that target tumor-specific mutant neoantigens—derived from products encoded by mutated genes in the tumor—is mostly limited to tumor-resident lymphocytes 1 , 2 , but whether these lymphocytes often occur in the circulation is unclear. We recently reported that intratumoral expression of the programmed cell death 1 (PD-1) receptor can guide the identification of the patient-specific repertoire of tumor-reactive CD8 + lymphocytes that reside in the tumor 3 . In view of these findings, we investigated whether PD-1 expression on peripheral blood lymphocytes could be used as a biomarker to detect T cells that target neoantigens. By using a high-throughput personalized screening approach, we identified neoantigen-specific lymphocytes in the peripheral blood of three of four melanoma patients. Despite their low frequency in the circulation, we found that CD8 + PD-1 + , but not CD8 + PD-1 − , cell populations had lymphocytes that targeted 3, 3 and 1 unique, patient-specific neoantigens, respectively. We show that neoantigen-specific T cells and gene-engineered lymphocytes expressing neoantigen-specific T cell receptors (TCRs) isolated from peripheral blood recognized autologous tumors. Notably, the tumor-antigen specificities and TCR repertoires of the circulating and tumor-infiltrating CD8 + PD-1 + cells appeared similar, implying that the circulating CD8 + PD-1 + lymphocytes could provide a window into the tumor-resident antitumor lymphocytes. Thus, expression of PD-1 identifies a diverse and patient-specific antitumor T cell response in peripheral blood, providing a novel noninvasive strategy to develop personalized therapies using neoantigen-reactive lymphocytes or TCRs to treat cancer.

Follicular regulatory T cells control humoral immune responses, but how these cells are in turn controlled has been unclear. Sharpe and colleagues demonstrate that signaling via PD-1 regulates number and function of these cells. CD4 + CXCR5 + Foxp3 + follicular regulatory T cells (T FR cells) inhibit humoral immunity mediated by CD4 + CXCR5 + Foxp3 − follicular helper T cells (T FH cells). Although the inhibitory receptor PD-1 is expressed by both cell types, its role in the differentiation of T FR cells is unknown. Here we found that mice deficient in PD-1 and its ligand PD-L1 had a greater abundance of T FR cells in the lymph nodes and that those T FR cells had enhanced suppressive ability. We also found substantial populations of T FR cells in mouse blood and demonstrated that T FR cells in the blood homed to lymph nodes and potently inhibited T FH cells in vivo . T FR cells in the blood required signaling via the costimulatory receptors CD28 and ICOS but were inhibited by PD-1 and PD-L1. Our findings demonstrate mechanisms by which the PD-1 pathway regulates antibody production and help reconcile inconsistencies surrounding the role of this pathway in humoral immunity.

BackgroundClinical benefit from programmed cell death 1 receptor (PD-1) inhibitors relies on reinvigoration of endogenous antitumor immunity. Nonetheless, robust immunological markers, based on circulating immune cell subsets associated with therapeutic efficacy are yet to be validated.MethodsWe isolated peripheral blood mononuclear cell from three independent cohorts of melanoma and Merkel cell carcinoma patients treated with PD-1 inhibitor, at baseline and longitudinally after therapy. Using multiparameter flow cytometry and cell sorting, we isolated four subsets of CD8+ T cells, based on PD-1 and TIGIT expression profiles. We performed phenotypic characterization, T cell receptor sequencing, targeted transcriptomic analysis and antitumor reactivity assays to thoroughly characterize each of these subsets.ResultsWe documented that the frequency of circulating PD-1+TIGIT+ (DPOS) CD8+ T-cells after 1 month of anti-PD-1 therapy was associated with clinical response and overall survival. This DPOS T-cell population was enriched in highly activated T-cells, tumor-specific and emerging T-cell clonotypes and T lymphocytes overexpressing CXCR5, a key marker of the CD8 cytotoxic follicular T cell population. Additionally, transcriptomic profiling defined a specific gene signature for this population as well as the overexpression of specific pathways associated with the therapeutic response.ConclusionsOur results provide a convincing rationale for monitoring this PD-1+TIGIT+ circulating population as an early cellular-based marker of therapeutic response to anti-PD-1 therapy.

The association between the tumor microenvironment (TME) and treatment response or survival has been a recent focus in several types of cancer. However, most study materials are resected specimens that were completely modified by prior chemotherapy; therefore, the unmodified host immune condition has not yet been clarified. The aim of the present study was to evaluate the relationship between TME assessed in pre–therapeutic biopsy samples and chemoresistance in esophageal cancer (EC). A total of 86 endoscopic biopsy samples from EC patients who received neoadjuvant chemotherapy (NAC) prior to surgery were evaluated for the number of intratumoral CD4+ lymphocytes (with/without Foxp3 expression), CD8+ lymphocytes (with/without PD‐1 expression), monocytes (CD14+) and macrophages (CD86+, CD163+ and CD206+) by multiplex immunohistochemistry (IHC). The number of tumor‐infiltrating CD206+ macrophages I significantly correlated with cT, cM, cStage and neutrophil/lymphocyte ratio (NLR), whereas the number of lymphocytes (including expression of Foxp3 and PD‐1) was not associated with clinico‐pathological features. The high infiltration of CD163+ or CD206+ macrophages was significantly associated with poor pathological response to NAC (P = 0.0057 and 0.0196, respectively). Expression of arginase‐1 in CD163+ macrophages tended to be higher in non–responders (29.4% vs 18.2%, P = 0.17). In addition, patients with high infiltration of M2 macrophages exhibited unfavorable overall survival compared to those without high infiltration of M2 macrophages (5‐year overall survival 57.2% vs 71.0%, P = 0.0498). Thus, a comprehensive analysis of TME using multiplex IHC revealed that M2 macrophage infiltration would be useful in predicting the response to NAC and long‐term survival in EC patients. The present study confirmed that pre–therapeutic M2 macrophage infiltration would be a useful biomarker in predicting the response to NAC and unfavorable survival among a variety of immune cells in EC patients. Our results support the possibility of using immunotherapy, targeting M2 macrophages, alongside conventional neoadjuvant chemotherapy.

Background Sepsis remains a major cause of mortality in critical care, for which specific treatments are lacking. The dysregulated response to infection seen in sepsis includes features of lymphocyte dysfunction and exhaustion, suggesting that immune-stimulatory therapy may improve outcomes in certain patient groups. Monoclonal antibodies targeting checkpoint molecules, such as programmed-death 1 protein (PD-1) and its ligand PD-L1, have shown success in stimulating the immune response in patients with cancer, and are being considered for future sepsis trials. The aims of this pilot study were to compare lymphocyte subset expression of PD-1 and its ligands between patients with sepsis and controls; to characterize serum levels of PD-1 and PD-L1 in patients with sepsis and controls, and determine if serum concentrations correlated with cell surface expression. Methods Expression levels of PD-1, PD-L1 and PD-L2 on four lymphocyte subsets (CD27 + CD19+ B cells, CD27-CD19+ B cells, CD27 + CD4+ T cells and CD27-CD4+ T cells) were compared between 22 patients with sepsis (including 11 survivors and 11 non-survivors) and 11 healthy controls using flow cytometry. Levels of soluble PD-1 and PD-L1 were also compared using commercially available ELISA kits. Results Expression of PD-1 and PD-L1 was higher on all lymphocyte subsets in patients with sepsis compared to controls ( p  < 0.05). PD-L2 expression on CD27+ B cells was also higher in patients with sepsis ( p  = 0.0317). There was differential expression of PD-1 by CD27 status, with expression being higher in the B and T cell subsets associated with memory status (CD27+ and CD27-, respectively; p  < 0.001). Higher PD-1 and PD-L1 expression was not associated with mortality or with a higher risk of nosocomial infection. There were no differences in levels of soluble PD-1 or PD-L1 between patients with sepsis and controls. Conclusions Higher expression of PD-1 by memory subpopulations of B cells and CD4+ T cells, with normal soluble PD-1 and PD-L1 in patients with sepsis, are novel findings. This information may be useful to enrich sepsis populations for trials of PD-1/PD-L1 blockade.

Dual blocker therapy (DBT) has the enhanced antitumor benefits than the monotherapy. Yet, few effective biomarkers are developed to monitor the therapy response. Herein, we investigate the DBT longitudinal plasma proteome profiling including 113 longitudinal samples from 22 patients who received anti-PD1 and anti-CTLA4 DBT therapy. The results show the immune response and cholesterol metabolism are upregulated after the first DBT cycle. Notably, the cholesterol metabolism is activated in the disease non-progressive group (DNP) during the therapy. Correspondingly, the clinical indicator prealbumin (PA), free triiodothyronine (FT3) and triiodothyronine (T3) show significantly positive association with the cholesterol metabolism. Furthermore, by integrating proteome and radiology approach, we observe the high-density lipoprotein partial remodeling are activated in DNP group and identify a candidate biomarker APOC3 that can reflect DBT response. Above, we establish a machine learning model to predict the DBT response and the model performance is validated by an independent cohort with balanced accuracy is 0.96. Thus, the plasma proteome profiling strategy evaluates the alteration of cholesterol metabolism and identifies a panel of biomarkers in DBT. Dual blockade therapy is currently being trialled for multiple tumour types, but efficacy is variable. Here, the authors use longitudinal proteomics profiling of 22 patients to develop a predictive model of therapy response.

The aim of this study was to investigate PD-L1 expression and its association with prognosis in esophageal squamous cell carcinoma (ESCC) before and after neoadjuvant chemotherapy (5-fluorouracil and cisplatin, NAC-FP). Using a database of 69 ESCC patients, we analyzed PD-L1 expression on tumor cells (TCs) and immune cells (ICs), as well as the density of CD8 tumor-infiltrating lymphocytes (TILs) in pretreatment biopsy specimens-versus-surgical specimens after resection. We determined the prognostic significance of these factors. The fraction of ESCC containing ICs expressing PD-L1 and having a high CD8 TIL density was significantly increased after neoadjuvant treatment. However, PD-L1 expression on TCs or ICs, and CD8 TIL density, was not significantly associated with patient survival in ESCC patients. NAC-FP induced PD-L1 expression on ICs and CD8 TILs in ESCC patients. This finding suggests that PD-1/PD-L1 blockade could be combined with NAC-FP to treat ESCC patients.

Background T follicular helper (Tfh) cells have been identified as a new category of helper T cells, which express CXCR5 on their surface and induce the production of antigen-specific antibodies. Many investigations have found morbid proliferation and/or activation of Tfh cells in systemic autoimmune and allergic diseases. It is also known that Tfh cells are regulated by regulatory B (Breg) cells in the deteriorating such diseases. Recently, CXCL13, a ligand of CXCR5, has been reported to increase in the peripheral blood and lungs of patients with idiopathic pulmonary fibrosis (IPF). This study aimed to investigate the involvement of Tfh cells and Breg cells in IPF. Methods Peripheral blood samples were obtained from 18 patients with IPF. We isolated heparinized peripheral blood mononuclear cells and investigated the proportions of Breg cells, Tfh cells, PD-1 + ICOS + Tfh cells (activated form of Tfh cells), and the Tfh-cell subsets by flow cytometry. These cell profiles were compared with those of 21 healthy controls. Furthermore, we investigated the correlations between profiles of lymphocytes and lung physiology. Results The median proportions of Tfh cells per total CD4 + T cells and of PD-1 + ICOS + proportion of Tfh cells per total Tfh cells was significantly more in the IPF patients (20.4 and 5.2%, respectively) compared with healthy controls (15.4 and 2.1%, respectively; p  = 0.042 and p  = 0.004, respectively). The proportion of Tfh2 cells per total Tfh cells was significantly higher and the proportion of Tfh17 was smaller in the IPF patients than healthy controls. The percentage of Breg cells to total B cells was significantly decreased in the IPF patients (median, 8.5%) compared with that in the controls (median, 19.7%; p  < 0.001). The proportion of Breg cells was positively correlated with the annual relative change in diffusing capacity of the lungs for carbon monoxide in the IPF patients ( r  = 0.583, p  = 0.018). Conclusion Proliferation and activation of Tfh cells and a decrease in Breg cells were observed in the peripheral blood of patients with IPF. The profile of the Tfh-cell subset also changed. Specific humoral immunity aberration would likely underlie complicated pathophysiology of IPF.

T cells are the primary cell subset involved in antitumor immunity. Their functions depend largely on the repertoire of surface receptors. This study investigates the association between the expression of CD28 and PD-1 molecules on peripheral blood T cells and prognosis in advanced breast cancer (BC) patients undergoing paclitaxel chemotherapy, along with their roles in anti-tumor immunity. Peripheral blood from 61 patients with advanced BC was analyzed by flow cytometry for immunophenotype before treatment. We investigated the effects of PD-1 and CD28 on anti-tumor responses of lymphocytes in two breast cancer cell lines in vitro. Patients with high CD28 and low PD-1 on T cells were more sensitive to chemotherapy. PD-1 blockade enhanced the cytotoxicity of peripheral blood mononuclear cells (PBMCs) against tumor cells with high expression of PD-L1, an effect dependent on CD28 expression on T cells. CD28 expression is associated with immune cell infiltration in BC tumor microenvironment, particularly CD8+ T effector memory (Tem) cells. The proportion of CD8+ Tem cells increased after treatment with anti-PD-1 antibodies in vitro. Clinical results show that most patients who do not respond to chemotherapy have high expression of CD3+PD-1+ and low expression of CD8+CD28+. Combining the two markers distinguished patients with progressive disease more accurately. Additionally, patients with low CD3+PD-1+ expression and high CD8+CD28+ expression had longer progression-free survival (PFS). The expression of CD28 and PD-1 on T cells can serve as potential biomarkers for assessing tumor progression, chemotherapy response and prognosis in advanced BC. BC patients with low PD-1 expression or PD-1 blockade exhibit increased induction of memory T cells during the anti-tumor immune response.