Abnormal expression of Tim-3 antigen on peripheral blood T cells is associated with progressive disease in osteosarcoma patients

Circulating immune cells and risk of osteosarcoma: a Mendelian randomization analysis

Objectives

Osteosarcoma (OS) is the primary bone tumor originating from transformed mesenchymal cells. It is unclear whether associations between specific circulating immune cells and OS are causal or due to bias. To clarify whether predicted genetically altered circulating immune cells are associated with OS development, we performed a two-sample Mendelian randomization (MR) analysis.

Methods

The genetic variants strongly associated with immune cell traits as instrumental variables (IVs) were used to perform MR analyses. The effect of specific immune cells on OS risk was measured using the summary statistics from the genome-wide association studies (GWAS).

Results

Our findings indicate that CD80 on CD62L+ myeloid dendritic cell and CD28-CD4-CD8- T-cell absolute count are positively associated with OS (CD80 on CD62L+ myeloid dendritic cell, OR: 3.41 [95% CI: 1.40 to 8.31], p = 0.007; CD28-CD4-CD8- T-cell absolute count, OR: 4.49 [95% CI: 1.29 to 15.62], p = 0.018). It is also found that CD20 has a negative effect on CD24+CD27+ B cell on OS (OR: 0.32 [95% CI: 0.14 to 0.72], p = 0.006) and a similar impact on IgD+ CD38- B cell on OS (OR: 0.19 [95% CI: 0.05 to 0.68], p = 0.011).

Conclusions

These findings illustrate that the genetic predisposition to specific immune cells can exert a causal effect on OS risk, which confirms the crucial role played by immunity in OS development. Particularly, the causal association between immune cells and OS underscores the evidence for exploring the new treatment strategy for OS in the future.

CircPVT1 promotes migration and invasion by regulating miR-490-5p/HAVCR2 axis in osteosarcoma cells

Circular RNAs (circRNAs) play an important role in the progression of osteosarcoma. However, the precise function of circPVT1 in osteosarcoma remains elusive. This study aims to explore the molecular mechanism underlying the involvement of circPVT1 in osteosarcoma cells. We quantified circPVT1 expression using qRT-PCR in both control and osteosarcoma cell lines. To investigate the roles of circPVT1, miR-490-5p and HAVCR2 in vitro, we separately conducted overexpression and inhibition experiments for circPVT1, miR-490-5p and HAVCR2 in HOS and U2OS cells. Cell migration was assessed through wound healing and transwell migration assays, and invasion was measured via the Matrigel invasion assay. To elucidate the regulatory mechanism of circPVT1 in osteosarcoma, a comprehensive approach was employed, including fluorescence in situ hybridization, qRT-PCR, Western blot, bioinformatics, dual-luciferase reporter assay and rescue assay. CircPVT1 expression in osteosarcoma cell lines surpassed that in control cells. The depletion of circPVT1 resulted in a notable reduction in the in vitro migration and invasion of osteosarcoma cells. Mechanism experiments revealed that circPVT1 functioned as a miR-490-5p sequester, and directly targeted HAVCR2. Overexpression of miR-490-5p led to a significant attenuation of migration and invasion of osteosarcoma cells, whereas HAVCR2 overexpression had the opposite effect, promoting these abilities. Additionally, circPVT1 upregulated HAVCR2 expression via sequestering miR-490-5p, thereby orchestrating the migration and invasion in osteosarcoma cells. CircPVT1 orchestrates osteosarcoma migration and invasion by regulating the miR-490-5p/HAVCR2 axis, underscoring its potential as a promising therapeutic target for osteosarcoma.

Cancer combination therapies by silencing of CTLA-4, PD-L1, and TIM3 in osteosarcoma

BACKGROUND

Osteosarcoma (OS) is the most common orthopedic neoplasm, with a high metastasis rate and a dismal prognosis despite surgery and chemotherapy. Immunotherapies have offered cancer patients a ray of optimism, but their impact on OS has been disappointing. The objective of this study is to assess the effect of mono, dual, and triple combinations of CTLA-4, PD-L1, and TIM3 blockade on OS cell viability, apoptosis, and migration.

METHOD

The MG-63 and U-2 OS cell lines were transfected with mono, dual, and triple combinations of siRNAs specific for CTLA-4, PD-L1, and TIM3. After evaluation for transfection efficacy by qRT-PCR, MTT assay and flow cytometry were applied to assess cell viability and apoptosis rate in siRNA-transfected cells, respectively. Ultimately, the migration of transfected cells was measured by wound healing assay.

RESULTS

First, the qRT-PCR analysis revealed that in siRNA-transfected OS cells, CTLA-4, PD-L1, and TIM3 were downregulated. The MTT assay and flow cytometry results confirmed that silencing of these immune checkpoints in dual or triple combinations, but not in the single-agent blockade, significantly decreases cell viability and increases apoptosis, respectively. These effects were more significant when triple silencing was performed. Finally, the wound healing assay revealed that dual and triple silencing of immune checkpoints significantly inhibit cell migration, with triple silencing exhibiting a greater effect.

CONCLUSION

Our findings suggest that triple blockade of CTLA-4, PD-L1, and TIM3 is an effective strategy for inhibiting tumor cell progression and migration in OS, which requires large-scale clinical investigations to be translated into broad therapeutic applicability for OS patients.

Novel Immunotherapies for Osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone sarcoma mainly affecting adolescents and young adults, which often progresses to pulmonary metastasis and leads to the death of OS patients. OS is characterized as a highly heterogeneous cancer type and the underlying pathologic mechanisms triggering tumor progress and metastasis are incompletely recognized. Surgery combined with neoadjuvant and postoperative chemotherapy has elevated 5-year survival to over 70% for patients with localized OS tumors, as opposed to only 20% of patients with recurrence and/or metastasis. Therefore, novel therapeutic strategies are needed to overcome the drawbacks of conventional treatments. Immunotherapy is gaining momentum for the treatment of OS with an increasing number of FDA-approved therapies for malignancies resistant to conventional therapies. Here, we review the OS tumor microenvironment and appraise the promising immunotherapies available in the management of OS.

Prognostic significance and therapeutic potentials of immune checkpoints in osteosarcoma

Although there exist manifold strategies for cancer treatment, researchers are obliged to develop novel treatments based on the challenges that arise. One of these recent treatment approaches is cancer immunotherapy, which enjoys various types of strategies itself. However, one of the most significant methods, in this regard, is employing immune checkpoint proteins (ICPs). Bone sarcomas have several subtypes, with the most common ones being chordoma, chondrosarcoma, Ewing sarcoma, and osteosarcoma. Although many aggressive treatment approaches, including radiotherapy, chemotherapy, and surgical resection, have been employed over the last decades, significantly improved outcomes have not been observed for Ewing sarcoma or osteosarcoma patients. Additionally, chordoma and chdrosarcoma resist against both radiation and chemotherapy. Accordingly, elucidating how recent therapies could affect bone sarcomas is necessary. Checkpoint inhibitors have attracted great attention for the treatment of several cancer types, including bone sarcoma. Herein, the recent advances of current immune checkpoint targets, such as anti-PD-1/PD-L1 and anti-CTLA-4 blockade, for the treatment of bone sarcoma have been reviewed.

On Demand Biosensors for Early Diagnosis of Cancer and Immune Checkpoints Blockade Therapy Monitoring from Liquid Biopsy

Recently, considerable interest has emerged in the development of biosensors to detect biomarkers and immune checkpoints to identify and measure cancer through liquid biopsies. The detection of cancer biomarkers from a small volume of blood is relatively fast compared to the gold standard of tissue biopsies. Traditional immuno-histochemistry (IHC) requires tissue samples obtained using invasive procedures and specific expertise as well as sophisticated instruments. Furthermore, the turnaround for IHC assays is usually several days. To overcome these challenges, on-demand biosensor-based assays were developed to provide more immediate prognostic information for clinicians. Novel rapid, highly precise, and sensitive approaches have been under investigation using physical and biochemical methods to sense biomarkers. Additionally, interest in understanding immune checkpoints has facilitated the rapid detection of cancer prognosis from liquid biopsies. Typically, these devices combine various classes of detectors with digital outputs for the measurement of soluble cancer or immune checkpoint (IC) markers from liquid biopsy samples. These sensor devices have two key advantages: (a) a small volume of blood drawn from the patient is sufficient for analysis, and (b) it could aid physicians in quickly selecting and deciding the appropriate therapy regime for the patients (e.g., immune checkpoint blockade (ICB) therapy). In this review, we will provide updates on potential cancer markers, various biosensors in cancer diagnosis, and the corresponding limits of detection, while focusing on biosensor development for IC marker detection.

Clinical Value of Combined Detection of Serum sTim-3 and Pepsinogen for Gastric Cancer Diagnosis

Purpose

The present study aimed to evaluate the clinical value of the combined detection of soluble T cell immunoglobulinand mucin domain molecule 3 (sTim-3) and pepsinogen (PG) in sera for gastric cancer (GC) diagnosis.

Patients and Methods

The double antibody sandwich method was used to establish a highly sensitive time-resolved fluorescence immunoassay for the detection of sTim-3. Serum sTim-3, PGI, and PGII levels in 149 GC patients (123 first-diagnosis GC patients and 26 post-GC patients), 81 patients with benign gastric disease (BGD), and 73 healthy controls were quantitatively detected. The clinical diagnostic value of the combined detection of sTim-3 and PG in GC was analyzed.

Results

Serum sTim-3 levels in GC (20.41 ± 9.55 ng/mL) and BGD (16.50 ± 9.76 ng/mL) patients were significantly higher (P < 0.001) than those in healthy controls (9.22 ± 3.40 ng/mL). Combined detection of sTim-3 and PGI/PGII (AUC: 0.9330, sensitivity: 86.44%, and specificity: 91.78%) showed a high diagnostic value for GC. When the level of PGI/PGII was less than 12.11 and that of sTim-3 was greater than 14.30 ng/mL, the positive rate of the control group was reduced to 0%, and the positive detection rate of GC was 54.47%. In addition, in post-operative patients, serum sTim-3 levels in the recurrence group (33.56 ± 4.91 ng/mL) were significantly higher than those in the no recurrence group (11.95 ± 5.16 ng/mL).

Conclusion

sTim-3 levels in BGD and GC sera were significantly higher than those in the control group sera. Additionally, sTim-3 serum levels can predict recurrence in post-operative patients. Compared with PG alone, the combined detection of serum PG and sTim-3 can significantly improve the detection sensitivity and specificity of BGD and GC.

Tumor-Associated Antigens (TAAs) for the Serological Diagnosis of Osteosarcoma

Osteosarcoma (OS) is the most common form of malignant bone tumor found in childhood and adolescence. Although its incidence rate is low among cancers, the prognosis of OS is usually poor. Although some biomarkers, such as p53, have been identified in OS, the association between the biomarkers and clinical outcome is not well understood. Thus, it is necessary to establish a method to identify patients diagnosed with OS at an early stage. It is becoming obvious that anti-tumor-associated antigens (TAAs) autoantibodies (TAAbs) in sera could be used as serological biomarkers in the detection of many different types of cancers. This notion indicates that TAAbs are considered as immunological “sentinels” associated with tumorigenesis underlying molecular events. It provides new insights into the molecular and cellular biology of the differential diagnosis of cancers. What’s more, it is reported that a customized TAA array could significantly increase the sensitivity/specificity. TAA arrays also have great application prospects in detecting cancer at an early stage, monitoring cancer progression, discovering new therapeutic targets, and designing personalized treatment. In this review, we provide an overview of the TAAs identified in OS as well as the possibility that TAAs and TAAbs system be used as biomarkers in the immunodiagnosis and prognosis of OS.

News on immune checkpoint inhibitors as immunotherapy strategies in adult and pediatric solid tumors

Immune checkpoint inhibitors (ICIs) have shown unprecedented benefits in various adult cancers, and this success has prompted the exploration of ICI therapy even in childhood malignances. Although the use of ICIs as individual agents has achieved disappointing response rates, combinational therapies are likely to promise better results. However, only a subset of patients experienced prolonged clinical effects, thus suggesting the need to identify robust bio-markers that predict individual clinical response or resistance to ICI therapy as the main challenge. In this review, we focus on how the use of ICIs in adult cancers can be translated into pediatric malignances. We discuss the physiological mechanism of action of each IC, including PD-1, PD-L1 and CTLA-4 and the new emerging ones, LAG-3, TIM-3, TIGIT, B7-H3, BTLA and IDO-1, and evaluate their prognostic value in both adult and childhood tumors. Furthermore, we offer an overview of preclinical models and clinical trials currently under investigation to improve the effectiveness of cancer immunotherapies in these patients. Finally, we outline the main predictive factors that influence the efficacy of ICIs, in order to lay the basis for the development of a pan-cancer immunogenomic model, able to direct young patients towards more specific immunotherapy.

Applying Osteosarcoma Immunology to Understand Disease Progression and Assess Immunotherapeutic Response

Osteosarcoma, the most common malignant bone tumor in children and adolescents, remains a complicated disease to treat; no new treatments have been developed in more than three decades. Due to the importance of the immune system in osteosarcoma disease progression, immunotherapeutic strategies have been explored to potentially improve long-term survival. However, most immunotherapeutics have not reached the level of success hoped would occur in this disease. Understanding the immune system in osteosarcoma will be key to optimizing treatments and improving patient outcomes. Therefore, immunophenotyping can be used as a very powerful tool to help better understand the complexity of the immune response seen in osteosarcoma and in the use of immunotherapy in this malignancy. This book chapter will provide an overview of the known immune responses seen in this disease and potential developments for the future of immunophenotyping. Indeed, it appears that being able to track the immune system throughout the disease and treatment of patients with osteosarcoma could allow for a personalized approach to immunotherapy.

TIM-3 expression and its association with overall survival in primary osteosarcoma

T-cell immunoglobulin and mucin domain-containing-3 (TIM-3) performs a critical function in immune tolerance by suppressing the activation and proliferation of T cells. TIM-3 serves an important role in tumor progression in a number of carcinomas, including non-small cell lung cancer, hepatitis B virus-associated hepatocellular carcinoma, Langerhans cell sarcoma, head and neck cancer and follicular B cell non-Hodgkin lymphoma. The aim of the present study was to evaluate the possible association of TIM-3 with the prognosis of osteosarcoma. TIM-3 expression was assessed by immunohistochemical analysis in osteosarcoma tissues. The association between TIM-3 expression and prognosis was examined. To assess the association between TIM-3 expression levels and clinicopathological features, a Fisher's exact test was used. TIM-3 overexpression was indicated to be associated with surgical treatment and survival. Kaplan-Meier analysis indicated that TIM-3 is an independent predictor of overall survival, and its overexpression was indicated to be associated with poor prognosis in patients with osteosarcoma. Additionally, reverse transcription-quantitative polymerase chain reaction and western blot analysis were carried out to evaluate TIM-3 expression levels in fresh tumor tissue samples, adjacent-tissue samples, osteosarcoma cell lines, and in an osteoblastic cell line. TIM-3 was indicated to be overexpressed in fresh osteosarcoma tissue samples and in osteosarcoma cell lines. In conclusion, TIM-3 overexpression is associated with poor survival among patients with osteosarcoma and may be a possible therapeutic target in these types of tumors.

Novel therapeutic strategies for spinal osteosarcomas

At the dawn of the third millennium, cancer has become the bane of twenty-first century man, and remains a predominant public health burden, affecting welfare and life expectancy globally. Spinal osteogenic sarcoma, a primary spinal malignant tumor, is a rare and challenging neoplastic disease to treat. After the conventional therapeutic modalities of chemotherapy, radiation and surgery have been exhausted, there is currently no available alternative therapy in managing cases of spinal osteosarcoma. The defining signatures of tumor survival are characterised by cancer cell ability to stonewall immunogenic attrition and apoptosis by various means. Some of these biomarkers, namely immune-checkpoints, have recently been exploited as druggable targets in osteosarcoma and many other different cancers. These promising strides made by the use of reinvigorated immunotherapeutic approaches may lead to significant reduction in spinal osteosarcoma disease burden and corresponding reciprocity in increase of survival rates. In this review, we provide the background to spinal osteosarcoma, and proceed to elaborate on contribution of the complex ecology within tumor microenvironment giving arise to cancerous immune escape, which is currently receiving considerable attention. We follow this section on the tumor microenvironment by a brief history of cancer immunity. Also, we draw on the current knowledge of treatment gained from incidences of osteosarcoma at other locations of the skeleton (long bones of the extremities in close proximity to the metaphyseal growth plates) to make a case for application of immunity-based tools, such as immune-checkpoint inhibitors and vaccines, and draw attention to adverse upshots of immune-checkpoint blockers as well. Finally, we describe the novel biotechnique of CRISPR/Cas9 that will assist in treatment approaches for personalized medication.

Interaction of Breast Cancer and Insulin Resistance on PD1 and TIM3 Expression in Peripheral Blood CD8 T Cells

Epidemiological evidence points to a link between insulin resistance (IR) and breast cancer (BrCA). Insulin plays a role in CD8+ T cells (CD8T) differentiation and function and affects adipocytokines levels. CD8T activity in BrCA is associated with favorable outcome; while PD1 and TIM3 are markers of CD8T exhaustion and play critical roles in the negative regulation of T cell responses. Patients with (BrCA) have high expression levels of PD1 on circulating. Therefore, we hypothesized that BrCA and IR could affect PD1 and/or TIM3 expression on circulating CD8T. We determine PD1 and TIM3 expression on CD8T and analyze the relationship of CD8T phenotype with serum insulin and plasma adipocytokines levels in the different groups. We enrolled four groups of treatment-naive patients: women without neoplasms (Neo-)/without IR (IR-), Neo-/with IR (IR+), BrCa/IR- and BrCa/IR+. We found interactions between BrCA and IR with respect to TIM3 on naïve and central memory (CM) CD8T subsets. Furthermore, BrCA had a greater PD1 + TIM3- CD8T frequency in CD8T subsets than Neo-. IR+ presented a significantly lower PD1 + TIM3- frequency in CD8T subsets compare to Non-IR. In addition, we found a negative correlation between insulin levels, HOMA and frequency of PD1 + TIM3- in CD8T and a positive correlation between adiponectin levels and the frequency PD1 + TIM3- in CD8T. The increased expression of PD1 on different subsets of CD8T from BrCa patients is consistent with immunological tolerance, whereas IR has a contrary effect. IR could have a deleterious role in the activation of CD8T that can be relevant to new BrCa immunotherapy.

Using the Spleen as an In Vivo Systemic Immune Barometer Alongside Osteosarcoma Disease Progression and Immunotherapy with α-PD-L1

Indications for immunotherapies are still unclear, and there is a great need for real-time patient immune status monitoring. In this study, we confirmed that the local and systemic immune profiles of an orthotopic osteosarcoma model with or without luciferase transfection were statistically equivalent. Next, we used flow cytometry to describe systemic immune cell populations influenced by osteosarcoma disease progression. When compared to vehicle-inoculated sham mice, it was found that tumor-bearing mice had significant immunophenotype disturbances at approximately 11 weeks after inoculation (at which time 90% of primary tumor-bearing mice have fulminant pulmonary metastases). Percent populations of natural killer cells and T regulatory cells were increased in the spleens of tumor-bearing mice (p < 0.0083) compared to shams. Additionally, T lymphocytes from spleens of tumor-bearing mice showed increased Tim-3/PD-1 exhaustion status (p < 0.0083). There were also increases in the percent populations of myeloid cells and overall M1/M2 macrophage marker expression on tumor-bearing mice spleens versus controls (p < 0.00714). Finally, treatment with 20 μg α-PD-L1 decreased T-cell exhaustion back to sham status, with a corresponding increase in CTLA-4 expression on cytotoxic T cells in the majority of mice tested. Checkpoint inhibition also increased splenic monocyte maturation and returned macrophage M1/M2 marker expression back to sham status. These data suggest that cancer induces systemic immune dysregulation and that these changes may be elucidated and utilized for treatment purposes by sampling the systemic immune environment via the spleen. In addition, treatment with the checkpoint inhibitor α-PD-L1 may neutralize but not overcome the systemic immunological changes induced by a progressing malignancy.

Combined Blockade of T Cell Immunoglobulin and Mucin Domain 3 and Carcinoembryonic Antigen-Related Cell Adhesion Molecule 1 Results in Durable Therapeutic Efficacy in Mice with Intracranial Gliomas

Background

Glioblastoma multiforme (GBM) evades immune surveillance by inducing immunosuppression via receptor-ligand interactions between immune checkpoint molecules. T cell immunoglobulin and mucin domain 3 (Tim-3) is a key checkpoint receptor responsible for exhaustion and dysfunction of T cells and plays a critical role in immunosuppression. Carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) has been recently identified as a heterophilic ligand for Tim-3.

Material/Methods

We established an intracranial GBM model using C57BL/6 mice and GL261 cells, and treated the mice with single or combined monoclonal antibodies (mAbs) against Tim-3/CEACAM1. The CD4⁺, CD8⁺, and regulatory T cells in brain-infiltrating lymphocytes were analyzed using flow cytometry, and the effector function of T cells was assessed using ELISA. We performed a rechallenge by subcutaneous injection of GL261 cells in the “cured” (>90 days post-orthotopic tumor implantation) and naïve mice.

Results

The mean survival time in the control, anti-Tim-3, anti-CEACAM1, and combined treatment groups was 29.8, 43.4, 42.3, and 86.0 days, respectively, with 80% of the mice in the combined group becoming long-term survivors showing immune memory against glioma cells. Infiltrating CD4⁺ and CD8⁺ T cells increased and immunosuppressive Tregs decreased with the combined therapy, which resulted in a markedly elevated ratio of CD4⁺ and CD8⁺ cells to Tregs. Additionally, plasma IFN-γ and TGF-β levels were upregulated and downregulated, respectively.

Conclusions

Our data indicate that combined blockade of Tim-3 and CEACAM1 generates robust therapeutic efficacy in mice with intracranial tumors, and provides a promising option for GBM immunotherapy.

Elevated frequencies of CD8 T cells expressing PD-1, CTLA-4 and Tim-3 within tumour from perineural squamous cell carcinoma patients

Perineural spread of tumour cells along cranial nerves is a severe complication of primary cutaneous squamous cell carcinomas of the head and neck region. While surgical excision of the tumour is the treatment of choice, removal of all the tumour is often complicated by the neural location and recurrence is frequent. Non-invasive immune treatments such as checkpoint inhibitor blockade may be useful in this set of tumours although little is understood about the immune response to perineural spread of squamous cell carcinomas. Immunohistochemistry studies suggest that perineural tumour contains a lymphocyte infiltrate but it is difficult to quantitate the different proportions of immune cell subsets and expression of checkpoint molecules such as PD-1, Tim-3 and CTLA-4. Using flow cytometry of excised perineural tumour tissue, we show that a T cell infiltrate is prominent in addition to less frequent B cell, NK cell and NKT cell infiltrates. CD8 T cells are more frequent than other T cells in the tumour tissue. Amongst CD8 T cells, the frequency of Tim-3, CTLA-4 and PD-1 expressing cells was significantly greater in the tumour relative to the blood, a pattern that was repeated for Tim-3, CTLA-4 and PD-1 amongst non-CD8 T cells. Using immunohistochemistry, PD-1 and PD-L1-expression could be detected in close proximity amongst perineural tumour tissue. The data suggest that perineural SCC contains a mixture of immune cells with a predominant T cell infiltrate containing CD8 T cells. Elevated frequencies of tumour-associated Tim-3⁺, CTLA-4⁺ and PD-1⁺ CD8 T cells suggests that a subset of patients may benefit from local antibody blockade of these checkpoint inhibitors.

Tim3/Gal9 interactions between T cells and monocytes result in an immunosuppressive feedback loop that inhibits Th1 responses in osteosarcoma patients

The Tim3/Gal9 pathway is associated with immunosuppression and worse clinical outcome in multiple cancers. To illustrate the specific mechanism of Tim3/Gal9 interaction in osteosarcoma, we examined expression, function, and regulation of Tim3/Gal9 in various cells from osteosarcoma patients. Data showed that CD4⁺ T cells, CD8⁺ T cells, and monocytes from both peripheral blood and tumor of osteosarcoma patients contained high frequencies of Tim3⁺ cells, while the Gal9 expression was primarily found in regulatory T cells (Tregs) from osteosarcoma patients and was elevated compared to that in non-cancer controls. The Tim3⁺ CD4⁺ and CD8⁺ T cells presented lower proliferation capacity compared to their Tim3^- counterparts, which could be reverted by blocking Tim3 or Gal9. Interestingly, purified Tim3⁺ CD4⁺ T cells secreted more interferon gamma (IFNγ) than purified Tim3^- CD4⁺ T cells, but IFNγ production by Tim3⁺ CD4⁺ T cells was vulnerable to Gal9-mediated suppression. In monocytes, Tim3 expression was associated with high interleukin (IL)-10 and low IL-12 cytokine secretion profile. Exogenous recombinant Gal9, as well as CD4⁺CD25⁺ Treg supernatant, further decreased IL-12 expression in monocytes. In CD4⁺ T cell-monocyte coculture experiments, Tim3⁺ monocytes inhibited IFNγ expression from total CD4⁺ T cells and the development of IFNγ response in naive CD4⁺ T cells. Blocking the Tim3/Gal9 pathway reverted these effects. Together, these results suggested that in osteosarcoma patients, Tim3 expression did not directly mediate immune suppression, but the interaction between Tim3⁺ T cells and monocytes, naive CD4⁺ T cells, and Gal9-expressing CD4⁺CD25⁺ Tregs could resulting in progressive suppression of Th1 responses.