Immunotherapy Targeting CCR8+ Regulatory T Cells Induces Antitumor Effects via Dramatic Changes to the Intratumor CD8+ T Cell Profile.

Regulatory T cells (Tregs) contribute to the formation of a tumor-immunosuppressive microenvironment. CCR8 is reportedly selectively expressed in tumor Tregs, and an anti-CCR8 Ab can exert potent antitumor effects by eliminating intratumor Tregs in murine tumor models. In this study, we analyzed changes to intratumor immunity after anti-CCR8 Ab administration, especially in CD8+ T cells, which are involved in cancer cell killing, using the CT26 colorectal carcinoma mouse model. Immunophenotyping of tumor-infiltrating cells by mass cytometry after Ab administration on day 5 of tumor inoculation revealed that CD8+ T cell subsets were dramatically altered in the CCR8 Ab-treated group, with an increase in naive cells and nonexhausted effector cells and a decrease in exhausted cells with high expression levels of TOX. These results were corroborated with flow cytometry analysis. Delayed administration of the anti-CCR8 Ab on day 9 or 12, when the amount of CCR8+ Tregs and CD8+ T cell exhaustion were more progressed, also resulted in a decrease in exhausted CD8+ T cells, leading to tumor regression. Finally, we confirmed that high CCR8+ Treg infiltration was associated with high TOX expression in CD8+ T cells in human cancer patients. In conclusion, administration of an anti-CCR8 Ab can dramatically alter the activation and exhaustion state of intratumor CD8+ T cells, resulting in strong antitumor effects. In cancer patients with an advanced tumor-immunosuppressive environment, CD8+ T cell exhaustion has progressed along with CCR8+ Treg induction. Therefore, targeted depletion of CCR8+ Tregs is expected to be effective in these patients.

CCR8-targeted specific depletion of clonally expanded Treg cells in tumor tissues evokes potent tumor immunity with long-lasting memory.

Foxp3-expressing CD25+CD4+ regulatory T cells (Tregs) are abundant in tumor tissues. Here, hypothesizing that tumor Tregs would clonally expand after they are activated by tumor-associated antigens to suppress antitumor immune responses, we performed single-cell analysis on tumor Tregs to characterize them by T cell receptor clonotype and gene-expression profiles. We found that multiclonal Tregs present in tumor tissues predominantly expressed the chemokine receptor CCR8. In mice and humans, CCR8+ Tregs constituted 30 to 80% of tumor Tregs in various cancers and less than 10% of Tregs in other tissues, whereas most tumor-infiltrating conventional T cells (Tconvs) were CCR8- CCR8+ tumor Tregs were highly differentiated and functionally stable. Administration of cell-depleting anti-CCR8 monoclonal antibodies (mAbs) indeed selectively eliminated multiclonal tumor Tregs, leading to cure of established tumors in mice. The treatment resulted in the expansion of CD8+ effector Tconvs, including tumor antigen-specific ones, that were more activated and less exhausted than those induced by PD-1 immune checkpoint blockade. Anti-CCR8 mAb treatment also evoked strong secondary immune responses against the same tumor cell line inoculated several months after tumor eradication, indicating that elimination of tumor-reactive multiclonal Tregs was sufficient to induce memory-type tumor-specific effector Tconvs. Despite induction of such potent tumor immunity, anti-CCR8 mAb treatment elicited minimal autoimmunity in mice, contrasting with systemic Treg depletion, which eradicated tumors but induced severe autoimmune disease. Thus, specific removal of clonally expanding Tregs in tumor tissues for a limited period by cell-depleting anti-CCR8 mAb treatment can generate potent tumor immunity with long-lasting memory and without deleterious autoimmunity.

The tissue-resident marker CD103 on peripheral blood T cells predicts responses to anti-PD-1 therapy in gastric cancer.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment. Since clinical benefits are limited to a subset of patients, we aimed to identify peripheral blood biomarkers that predict the efficacy of the anti-programmed cell death protein 1 (PD-1) antibody (nivolumab) in patients with gastric cancer. METHODS: We collected peripheral blood samples from gastric cancer patients (n = 29) before and after treatment with nivolumab and investigated the relationship between the frequency of surface or intracellular markers among nivolumab-binding PD-1+CD8+ T cells and treatment responses using multicolor flow cytometry. The tumors, lymph nodes, and peripheral blood of gastric cancer patients who underwent gastrectomy following nivolumab treatment were collected, and nivolumab-binding PD-1+CD8+ T cells in these tissue samples were characterized. RESULTS: Patients with a high frequency of CD103 among PD-1+CD8+ T cells in peripheral blood 2 weeks after the start of treatment had significantly better progression-free survival than the low group (P = 0.032). This CD103+PD-1+CD8+ T cell population mainly consisted of central memory T cells, showing the high expression of Ki-67 and few cytotoxic granules. In contrast, effector memory T cells were more frequently observed among CD103+PD-1+CD8+ T cells in tumors, which implied a change in the differentiated status of central memory T cells in lymph nodes and peripheral blood to effector memory T cells in tumors during the treatment with ICIs. CONCLUSIONS: A high frequency of CD103 among PD-1+CD8+ T cells 2 weeks after nivolumab treatment in patients with advanced gastric cancer may be a useful biomarker for predicting the efficacy of anti-PD-1 therapy.

The impact of ICOS+ regulatory T cells and Helicobacter pylori infection on the prognosis of patients with gastric and colorectal cancer: potential prognostic benefit of pre-operative eradication therapy.

It remains unclear whether Helicobacter pylori (H. pylori), a major cause of gastric cancer (GC), is involved in other intestinal cancers. In our previous study, ICOS+ Foxp3+ CD4+ T cells (ICOS+ Tregs) in GC tumors were identified as effector Tregs and associated with H. pylori. In the present study, the impact of ICOS+ Tregs on not only GC, but also colorectal cancer (CRC) and their prognosis was investigated in association with H. pylori. Tissue-infiltrating lymphocytes (TILs) purified from fresh tumor and sera were obtained from GC and CRC patients prospectively. % ICOS+ Tregs were analyzed by flow cytometry and their production of anti-H. pylori antibody (Hp-Ab) in sera was detected by ELISA. % ICOS+ Tregs were higher in GC and CRC patients with Hp-Ab than in those without Hp-Ab, including eradicated patients. ICOS+ Tregs purified had higher potential to produce IL-10 than ICOS- Tregs. For prognostic analysis, immunohistochemical analysis and ELISA were performed using archival fixed specimens and frozen sera, respectively, obtained from GC and CRC patients. Overall survival was longer in patients with low % ICOS+ Tregs than in those with high % ICOS+ Tregs, and patients with Hp-Ab showed shorter recurrence-free survival than those without Hp-Ab. These results suggested that ICOS+ Tregs in GC and CRC patients were closely associated with H. pylori in gastric epithelium and their prognosis, and that pre-operative H. pylori eradication has potential as a novel immunotherapy for GC and CRC patients.

PD-1+ Tim3+ tumor-infiltrating CD8 T cells sustain the potential for IFN-γ production, but lose cytotoxic activity in ovarian cancer.

Persistent exposure to tumor antigens results in exhausted tumor-infiltrating T cells (TILs) that express the immune checkpoint molecules, PD-1 and Tim3, and lack anti-tumor immunity. To examine the exhausted status of TILs in ovarian cancer, the potential for cytokine production, proliferation and cytotoxicity by purified PD-1+ Tim3+ CD8 TILs was assessed. The production of IFN-γ and TNF-α by PD-1+ Tim3+ CD8 TILs remained the same in an intracellular cytokine staining assay and was higher in a cytokine catch assay than that by PD-1- Tim3- and PD-1+ Tim3- CD8 TILs. %Ki67+ was higher in PD-1+ Tim3+ CD8 TILs than in PD-1- Tim3- CD8 TILs. However, patients with high PD-1+ Tim3+ CD8 TILs had a poor prognosis. The potential for cytotoxicity was then examined. %Perforin+ and %granzyme B+ were lower in PD-1+ Tim3+ CD8 TILs than in PD-1- Tim3- and PD-1+ Tim3- CD8 TILs. To observe the potential for direct cytotoxicity by T cells, a target cell line expressing membrane-bound anti-CD3scFv was newly established and a cytotoxic assay targeting these cells was performed. The cytotoxicity of PD-1+ Tim3+ CD8 TILs was significantly lower than that of PD-1- Tim3- and PD-1+ Tim3- CD8 TILs. Even though PD-1+ Tim3+ CD8 TILs in ovarian cancer showed a sustained potential for cytokine production and proliferation, cytotoxicity was markedly impaired, which may contribute to the poor prognosis of patients with ovarian cancer. Among the impaired functions of exhausted TILs, cytotoxicity may be an essential target for cancer immunotherapy.

Docetaxel Upregulates HMGB1 Levels in Non-small Cell Lung Cancer.

Immune checkpoint inhibitors (ICIs) exert beneficial effects in non-small cell lung cancer (NSCLC) patients. However, ICIs are only advantageous for a limited population of NSCLC patients. Therefore to enhance their effects, combination therapies with ICIs have been developed. To identify preferable chemotherapy to combine with ICIs against lung cancer, we examined immunological effects of docetaxel compared with epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI). We found no difference in peripheral lymphocyte counts and ratio of their subpopulations in lung cancer patients before and after both treatments. On the other hand, plasma levels of high-mobility group box 1 (HMGB1), a damage-associated molecular pattern (DAMP) protein, showed significant increase after docetaxel treatment. Furthermore, we investigated effects of HMGB1 on tumor-infiltrating immune cells obtained from surgically resected tumor tissue from NSCLC patients. When the tumor infiltrating cells were stimulated with HMGB1, CD11c+ cells showed increased expression of activation markers. These findings imply that docetaxel could be involved in anti-tumor immunity via HMGB1. Therefore docetaxel might be a candidate for combination treatment with ICIs.

Peri-operative monocyte count is a marker of poor prognosis in gastric cancer: increased monocytes are a characteristic of myeloid-derived suppressor cells.

Gastric cancer (GC) is the most common malignant tumor in digestive organs, and the prognosis of GC patients who have undergone surgery remains poor because of frequent recurrence. Therefore, the identification of new markers to predict the outcome of these patients is needed. Monocyte count is a negative prognostic factor associated with inflammation. We investigated the relationship between peripheral monocytes in the peri-operative period and prognosis in GC patients. A high pre-operative monocyte count was identified as a prognostic factor in a retrospective analysis of 278 stage II and III GC patients who underwent curative gastrectomy. In contrast, an increased post-operative monocyte count compared to the pre-operative monocyte count was a marker of poor prognosis, particularly for early relapse. In a prospective analysis of 75 GC patients, a subset of the increased post-operative monocytes was similar to CD14+ HLA-DR- CD11b+ CD33+ cells by flow cytometry, and these monocytes produced IDO and arginase and suppressed T cell functions; therefore, we classified these cells as monocytic myeloid-derived suppressive cells (M-MDSCs). Peri-operative neutrophils and C-reactive protein (CRP), which are also related to inflammation, did not affect the prognosis of GC patients, and a neutrophil immunosuppressive function was not observed. These results suggest that peripheral monocytes in the peri-operative period in GC patients are a useful marker for the prognosis of GC patients, and a subset of increased post-operative monocytes may be characterized as M-MDSCs.

S-531011, a Novel Anti-Human CCR8 Antibody, Induces Potent Antitumor Responses through Depletion of Tumor-Infiltrating CCR8-Expressing Regulatory T Cells.

Although regulatory T cells (Treg) are inhibitory immune cells that are essential for maintaining immune homeostasis, Tregs that infiltrate tumor tissue promote tumor growth by suppressing antitumor immunity. Selective reduction of tumor-infiltrating Tregs is, therefore, expected to activate antitumor immunity without affecting immune homeostasis. We previously reported that selective Treg depletion targeted by a C-C motif chemokine receptor 8 (CCR8) resulted in induction of strong antitumor immunity without any obvious autoimmunity in mouse models. Thus, herein, we developed a novel humanized anti-CCR8 monoclonal antibody, S-531011, aimed as a cancer immunotherapy strategy for patients with cancer. S-531011 exclusively recognized human CCR8 among all chemokine receptors and showed potent antibody-dependent cell-mediated cytotoxicity activity toward CCR8+ cells and neutralization activity against CCR8-mediated signaling. We observed that S-531011 reduced tumor-infiltrating CCR8+ Tregs and induced potent antitumor activity in a tumor-bearing human-CCR8 knock-in mouse model. Moreover, combination therapy with S-531011 and anti-mouse programmed cell death 1 (PD-1) antibody strongly suppressed tumor growth compared with anti-PD-1 antibody alone with no observable adverse effects. S-531011 also depleted human tumor-infiltrating Tregs, but not Tregs derived from human peripheral blood mononuclear cells. These results suggest that S-531011 is a promising drug for inducing antitumor immunity without severe side effects in the clinical setting.

T cell immunity in interstitial lung disease with non-small cell lung cancer patients.

OBJECTIVES: Limited treatment options are available for non-small cell lung cancer (NSCLC) patients with interstitial lung disease (ILD). The rationale for immunotherapy and its adverse events for NSCLC with ILD remains unclear. In this study, we examined T cell profiles and functions in the lung tissues of NSCLC patients with or without ILD to provide evidence for the potential mechanism of immune checkpoint inhibitor (ICI)-related pneumonitis in NSCLC patients with ILD. MATERIAL AND METHODS: We investigated T cell immunity in the lung tissues of NSCLC patients with ILD to support the application of immunotherapy for these patients. We analyzed T cell profiles and functions in surgically resected lung tissues from NSCLC patients with and without ILD. The T cell profiles of infiltrating cells in lung tissues were analyzed by flow cytometry. T cell functions were measured based on cytokine production by T cells stimulated with phorbol 12-myristate 13-acetate and ionomycin. RESULTS: The percentages of CD4+ T cells expressing immune checkpoint molecules (Tim-3, ICOS, and 4-1BB), CD103+CD8+ T cells, and regulatory T (Treg) cells were higher in NSCLC patients with than in those without ILD. A functional analysis of T cells in lung tissues indicated that CD103+CD8+ T cells positively correlated with IFNγ production, whereas Treg cells negatively correlated with IFNγ and TNFα production. Cytokine production by CD4+ and CD8+ T cells did not significantly differ between NSCLC patients with and without ILD, except for TNFα production by CD4+ T cells being lower in the former than in the latter. CONCLUSION: In NSCLC patients with ILD stable for surgery, T cells were active participants and balanced in part by Treg cells in lung tissues, suggesting the potential development of ICI-related pneumonitis in NSCLC patients with ILD.

Tumor-infiltrating ICOS+ Effector Regulatory T-Cells in Oral Squamous Cell Carcinoma as a Promising Biomarker for Prognosis and 'Hot' Tumor.

BACKGROUND: Tumor immunity in the tumor microenvironment is activated in patients with feasible clinical responses to immune checkpoint inhibitors. The immunological profile of tumor-infiltrating lymphocytes (TILs) obtained from patients with oral squamous cell carcinoma (OSCC) was examined in relation to their prognosis. MATERIALS AND METHODS: Surface antigens, including immune checkpoint molecules, on TILs from 31 patients with primary OSCC were analyzed by flow cytometry. The activation status of TILs was examined through a heatmap analysis and unsupervised clustering classified patients into groups with activated or inactivated TILs. A supervised machine-learning algorithm for single-cell analyses in relation to prognosis was run using the Cluster Identification, Characterization, and Regression (CITRUS) program. RESULTS: None of surface antigens were related to prognosis. The CITRUS program revealed a relationship between CD45RA-CD4+ CD25high inducible T-cell co-stimulator (ICOS)+ TILs and recurrence, and also identified a similar fraction significantly specific to the group with activated TILs. The disease-free survival rate for patients with ≥95% ICOS+ TILs was significantly lower than that for those with <95% ICOS+ TILs. Furthermore, a review of clinicopathological factors related to prognosis identified the percentage of ICOS+ TILs to be an independent prognostic factor for patients with OSCC. CONCLUSION: CD25highICOS+ regulatory T-cells in TILs have potential as a biomarker for predicting recurrence after surgical treatment and clinical responses to immune checkpoint inhibitors in patients with OSCC.

The impact of CCR8+ regulatory T cells on cytotoxic T cell function in human lung cancer.

Regulatory T cells (Tregs) suppress the host immune response and maintain immune homeostasis. Tregs also promote cancer progression and are involved in resistance to immune checkpoint inhibitor treatments. Recent studies identified selective CCR8 expression on tumor-infiltrating Tregs; CCR8+ Tregs have been indicated as a possible new target of cancer immunotherapy. Here, we investigated the features of CCR8+ Tregs in lung cancer patients. CCR8+ Tregs were highly activated and infiltration of CCR8+ Tregs in tumors was associated with poor prognosis in lung cancer patients. We also investigated their immune suppressive function, especially the influence on cytotoxic T lymphocyte cell function. The Cancer Genome Atlas analysis revealed that CD8 T cell activities were suppressed in high CCR8-expressing tumors. Additionally, depletion of CCR8+ cells enhanced CD8 T cell function in an ex vivo culture of lung tumor-infiltrating cells. Moreover, CCR8+ Tregs, but not CCR8- Tregs, induced from human PBMCs markedly suppressed CD8 T cell cytotoxicity. Finally, we demonstrated the therapeutic effect of targeting CCR8 in a murine model of lung cancer. These findings reveal the significance of CCR8+ Tregs for immunosuppression in lung cancer, especially via cytotoxic T lymphocyte cell suppression, and suggest the potential value of CCR8-targeted therapy for cancer treatment.