TIM-3 in Leukemia; Immune Response and Beyond

Bone marrow microenvironment in myelodysplastic neoplasms: insights into pathogenesis, biomarkers, and therapeutic targets

Myelodysplastic neoplasms (MDS) represent a heterogeneous group of malignant hematopoietic stem and progenitor cell (HSPC) disorders characterized by cytopenia, ineffective hematopoiesis, as well as the potential to progress to acute myeloid leukemia (AML). The pathogenesis of MDS is influenced by intrinsic factors, such as genetic insults, and extrinsic factors, including altered bone marrow microenvironment (BMM) composition and architecture. BMM is reprogrammed in MDS, initially to prevent the development of the disease but eventually to provide a survival advantage to dysplastic cells. Recently, inflammation or age-related inflammation in the bone marrow has been identified as a key pathogenic mechanism for MDS. Inflammatory signals trigger stress hematopoiesis, causing HSPCs to emerge from quiescence and resulting in MDS development. A better understanding of the role of the BMM in the pathogenesis of MDS has opened up new avenues for improving diagnosis, prognosis, and treatment of the disease. This article provides a comprehensive review of the current knowledge regarding the significance of the BMM to MDS pathophysiology and highlights recent advances in developing innovative therapies.

Spatial and multiomics analysis of human and mouse lung adenocarcinoma precursors reveals TIM-3 as a putative target for precancer interception

How tumor microenvironment shapes lung adenocarcinoma (LUAD) precancer evolution remains poorly understood. Spatial immune profiling of 114 human LUAD and LUAD precursors reveals a progressive increase of adaptive response and a relative decrease of innate immune response as LUAD precursors progress. The immune evasion features align the immune response patterns at various stages. TIM-3-high features are enriched in LUAD precancers, which decrease in later stages. Furthermore, single-cell RNA sequencing (scRNA-seq) and spatial immune and transcriptomics profiling of LUAD and LUAD precursor specimens from 5 mouse models validate high TIM-3 features in LUAD precancers. In vivo TIM-3 blockade at precancer stage, but not at advanced cancer stage, decreases tumor burden. Anti-TIM-3 treatment is associated with enhanced antigen presentation, T cell activation, and increased M1/M2 macrophage ratio. These results highlight the coordination of innate and adaptive immune response/evasion during LUAD precancer evolution and suggest TIM-3 as a potential target for LUAD precancer interception.

Updates in novel immunotherapeutic strategies for relapsed/refractory AML

Acute myeloid leukemia (AML) is a severe hematological malignancy with poor outcomes, particularly in older adults. Traditional treatment options like high-dose chemotherapy often lead to refractory or relapsed AML, with even worse outcomes. New therapies for relapsed and refractory AML are needed, and this review explores the most recent advancements in immunotherapy in AML. Checkpoint Inhibitors utilizing innate or adaptive immune targeting have shown potential to improve AML outcomes when combined with hypomethylating agents and chemotherapy. The use of adoptive cell therapy in AML demonstrates promising early data, however, there is a need for better target selection. Although early in development, both vaccine therapy as well as stimulator of interferon genes (STING) agonists have potential to enhance the innate immune response to overcome AML's immune evasion. Immunotherapy has become a promising approach for AML treatment, especially in refractory and relapsed AML, especially in patients who are not eligible for allogeneic stem cell transplants. Future research should focus on a deeper understanding of the immune microenvironment to identify the most critical targets for optimization, as well as personalized therapeutic combination strategies. Here we present a comprehensive overview of the recent developments in immunotherapy for relapsed and refractory AML.

TOX2 nuclear-cytosol translocation is linked to leukemogenesis of acute T-cell leukemia by repressing TIM3 transcription

Nuclear factors TOX and TOX2 upregulate TIM3 expression and lead to T-cell exhaustion in malignancies. Here, we demonstrate two distinct TIM3 expression patterns (high & low) with high TOX and TOX2 levels in T-cell acute lymphoblastic leukemia (T-ALL) specimens and cell lines. However, the mechanisms regulated by TOX and TIM3 signaling in leukemogenesis are unclear. We found that TOX and TOX2 proteins each directly upregulated HAVCR2 transcription, while the cellular localization of TOX2 was different in Jurkat and MOLT3 cells (nucleus) and lymphoblastic cell T2 and normal T cells (cytoplasm). Nuclear TOX and TOX2 formed a protein complex and repressed HAVCR2 promoter activity by recruiting transcriptional corepressor LCOR and deacetylase HDAC3. The nuclear-cytosol translocation of TOX2 was deacetylation-dependent and cooperatively mediated by deacetylase Sirt1 and kinase TBK1. Radiation damage induced TOX2 nuclear translocation and decreased Sirt1, TIM3, and caspase 1 expression in normal T cells. Accordingly, knockdown of TOX, TOX2 or LCOR; HDAC3 inhibition; or TIM3 overexpression induced Jurkat cell apoptosis in vitro and slow growth in vivo. Thus, our findings demonstrate a novel regulatory mechanism involving TOX-TOX2 and the TIM3 pathway in the leukemogenesis of T-ALL.

T-Cell Immunoglobulin and Mucin Domain 3 (TIM-3) Gene Expression as a Negative Biomarker of B-Cell Acute Lymphoblastic Leukemia

B-cell acute lymphoblastic leukemia (B-ALL) accounts for 85% of all childhood ALL. Malignancies exhaust T and B cells, resulting in an increased expression of immune checkpoint receptors (ICRs), such as T-cell immunoglobulin and mucin domain 3 (TIM-3). TIM-3 has been found to be dysregulated in different types of cancer. However, there is a lack of rigorous studies on the TIM-3 expression in B-ALL. The current study aimed to measure the expression of TIM-3 at the gene and protein levels and evaluate the potential of TIM-3 as a biomarker in B-ALL. A total of 28 subjects were recruited between 2021 and 2023, comprising 18 subjects diagnosed with B-ALL and 10 non-malignant healthy controls. The B-ALL patients were divided into three groups: newly diagnosed (four patients), in remission (nine patients), and relapse/refractory (five patients). The expression levels of TIM-3 were evaluated using the real-time qPCR and ELISA techniques. The results revealed that the TIM-3 expression was significantly downregulated in the malignant B-ALL patients compared to the non-malignant healthy controls in the mRNA (FC = -1.058 ± 0.3548, p = 0.0061) and protein blood serum (p = 0.0498) levels. A significant TIM-3 gene reduction was observed in the relapse/refractory cases (FC = -1.355 ± 0.4686, p = 0.0327). TIM-3 gene expression allowed for significant differentiation between patients with malignant B-ALL and non-malignant healthy controls, with an area under the curve (AUC) of 0.706. The current study addressed the potential of reduced levels of TIM-3 as a negative biomarker for B-ALL patients.

Blockade of PD-1 and TIM-3 Ameliorates CD8+ T Cell Exhaustion in a Mouse Model of Chronic Myeloid Leukemia

The immune system plays a pivotal role in controlling chronic myeloid leukemia (CML). CD8+ T cell exhaustion results in reduced effectiveness of T cell-mediated immunity, thereby contributing to disease progression. This study intends to figure out whether the combined blockade of inhibitory molecules TIM-3/PD-1 can affect CD8+ T cell exhaustion in CML. A CML mouse model was established via transplantation of bone marrow cells transduced with BCR-ABL-expressing retrovirus vectors. PD-1 and TIM-3 signaling were blocked using corresponding molecular antibodies. Flow cytometry analysis was conducted to detect cell surface molecules and intracellular cytokines. ELISA was employed for measuring cytokine concentrations in the culture medium. The results showed that TIM-3 and PD-1 were coexpressed on exhausted CD8+ T cells from CML mice. Combined blockade of PD-1/TIM3 synergistically delayed CML progression in mice. Moreover, ex vivo experiments showed that their co-blockade promoted the proliferation and cytokine secretion of CD8+ T cells isolated from CML mice. In conclusion, blocking TIM-3 and PD-1 improves exhausted CD8+ T cell function in CML.

Construction of an immune-related prognostic signature and lncRNA-miRNA-mRNA ceRNA network in acute myeloid leukemia

The progression of acute myeloid leukemia (AML) is influenced by the immune microenvironment in the bone marrow and dysregulated intracellular competing endogenous RNA (ceRNA) networks. Our study utilized data from UCSC Xena, The Cancer Genome Atlas Program, the Gene Expression Omnibus, and the Immunology Database and Analysis Portal. Using Cox regression analysis, we identified an immune-related prognostic signature. Genomic analysis of prognostic messenger RNA (mRNA) was conducted through Gene Set Cancer Analysis (GSCA), and a prognostic ceRNA network was constructed using the Encyclopedia of RNA Interactomes. Correlations between signature mRNAs and immune cell infiltration, checkpoints, and drug sensitivity were assessed using R software, gene expression profiling interactive analysis (GEPIA), and CellMiner, respectively. Adhering to the ceRNA hypothesis, we established a potential long noncoding RNA (lncRNA)/microRNA (miRNA)/mRNA regulatory axis. Our findings pinpointed 9 immune-related prognostic mRNAs (KIR2DL1, CSRP1, APOBEC3G, CKLF, PLXNC1, PNOC, ANGPT1, IL1R2, and IL3RA). GSCA analysis revealed the impact of copy number variations and methylation on AML. The ceRNA network comprised 14 prognostic differentially expressed lncRNAs (DE-lncRNAs), 6 prognostic DE-miRNAs, and 3 prognostic immune-related DE-mRNAs. Correlation analyses linked these mRNAs' expression to 22 immune cell types and 6 immune checkpoints, with potential sensitivity to 27 antitumor drugs. Finally, we identified a potential LINC00963/hsa-miR-431-5p/CSRP1 axis. This study offers innovative insights for AML diagnosis and treatment through a novel immune-related signature and ceRNA axis. Identified novel biomarkers, including 2 mRNAs (CKLF, PNOC), 1 miRNA (hsa-miR-323a-3p), and 10 lncRNAs (SNHG25, LINC01857, AL390728.6, AC127024.5, Z83843.1, AP002884.1, AC007038.1, AC112512, AC020659.1, AC005921.3) present promising candidates as potential targets for precision medicine, contributing to the ongoing advancements in the field.

Dual-targeting CD33/CD123 NANOBODY T-cell engager with potent anti-AML activity and good safety profile

ABSTRACT

Novel therapies are needed for effective treatment of acute myeloid leukemia (AML). Relapse is common and salvage treatment with cytotoxic chemotherapy is rarely curative. CD123 and CD33, 2 clinically validated targets in AML, are jointly expressed on blasts and leukemic stem cells in >95% of patients with AML. However, their expression is heterogenous between subclones and between patients, which may affect the efficacy of single-targeting agents in certain patient populations. We present here a dual-targeting CD33/CD123 NANOBODY T-cell engager (CD33/CD123-TCE) that was designed to decrease the risk of relapse from possible single antigen-negative clones and to increase coverage within and across patients. CD33/CD123-TCE killed AML tumor cells expressing 1 or both antigens in vitro. Compared with single-targeting control compounds, CD33/CD123-TCE conferred equal or better ex vivo killing of AML blasts in most primary AML samples tested, suggesting a broader effectiveness across patients. In a disseminated cell-line-derived xenograft mouse model of AML, CD33/CD123-TCE cleared cancer cells in long bones and in soft tissues. As cytokine release syndrome is a well-documented adverse effect of TCE, the compound was tested in a cytokine release assay and shown to induce less cytokines compared to a CD123 single-targeting control. In an exploratory single-dose nonhuman primate study, CD33/CD123-TCE revealed a favorable PK profile. Depletion of CD123 and CD33 expressing cells was observed, but there were neither signs of cytokine release syndrome nor clinical signs of toxicity. Taken together, the CD33/CD123 dual-targeting NANOBODY TCE exhibits potent and safe anti-AML activity and promises a broad patient coverage.

To develop a prognostic model for neoadjuvant immunochemotherapy efficacy in esophageal squamous cell carcinoma by analyzing the immune microenvironment

Objective

The choice of neoadjuvant therapy for esophageal squamous cell carcinoma (ESCC) is controversial. This study aims to provide a basis for clinical treatment selection by establishing a predictive model for the efficacy of neoadjuvant immunochemotherapy (NICT).

Methods

A retrospective analysis of 30 patients was conducted, divided into Response and Non-response groups based on whether they achieved major pathological remission (MPR). Differences in genes and immune microenvironment between the two groups were analyzed through next-generation sequencing (NGS) and multiplex immunofluorescence (mIF). Variables most closely related to therapeutic efficacy were selected through LASSO regression and ROC curves to establish a predictive model. An additional 48 patients were prospectively collected as a validation set to verify the model's effectiveness.

Results

NGS suggested seven differential genes (ATM, ATR, BIVM-ERCC5, MAP3K1, PRG, RBM10, and TSHR) between the two groups (P < 0.05). mIF indicated significant differences in the quantity and location of CD3+, PD-L1+, CD3+PD-L1+, CD4+PD-1+, CD4+LAG-3+, CD8+LAG-3+, LAG-3+ between the two groups before treatment (P < 0.05). Dynamic mIF analysis also indicated that CD3+, CD8+, and CD20+ all increased after treatment in both groups, with a more significant increase in CD8+ and CD20+ in the Response group (P < 0.05), and a more significant decrease in PD-L1+ (P < 0.05). The three variables most closely related to therapeutic efficacy were selected through LASSO regression and ROC curves: Tumor area PD-L1+ (AUC= 0.881), CD3+PD-L1+ (AUC= 0.833), and CD3+ (AUC= 0.826), and a predictive model was established. The model showed high performance in both the training set (AUC= 0.938) and the validation set (AUC= 0.832). Compared to the traditional CPS scoring criteria, the model showed significant improvements in accuracy (83.3% vs 70.8%), sensitivity (0.625 vs 0.312), and specificity (0.937 vs 0.906).

Conclusion

NICT treatment may exert anti-tumor effects by enriching immune cells and activating exhausted T cells. Tumor area CD3+, PD-L1+, and CD3+PD-L1+ are closely related to therapeutic efficacy. The model containing these three variables can accurately predict treatment outcomes, providing a reliable basis for the selection of neoadjuvant treatment plans.

Beyond inhibition against the PD-1/PD-L1 pathway: development of PD-L1 inhibitors targeting internalization and degradation of PD-L1

Tumor cells hijack the programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) pathway to suppress the immune response through overexpressing PD-L1 to interact with PD-1 of T cells. With in-depth ongoing research, tumor-intrinsic PD-L1 is found to play important roles in tumor progression without interaction with PD-1 expressed on T cells, which provides an additional important target and therapeutic approach for development of PD-L1 inhibitors. Existing monoclonal antibody (mAb) drugs against the PD-1/PD-L1 pathway generally behave by conformationally blocking the interactions of PD-1 with PD-L1 on the cell surface. Beyond general inhibition of the protein-protein interaction (PPI), inhibitors targeting PD-L1 currently focus on the functional inhibition of the interaction between PD-1/PD-L1 and degradation of tumor-intrinsic PD-L1. This perspective will clarify the evolution of PD-L1 inhibitors and provide insights into the current development of PD-L1 inhibitors, especially targeting internalization and degradation of PD-L1.

Establishment of novel anti-TIM-3 antibodies interfering with its binding to ligands

The T cell immunoglobulin and mucin-domain containing-3 (TIM-3) receptor has gained significant attention as a promising target for cancer immunotherapy. The inhibitory effect of T cells by TIM-3 is mediated through the interaction between TIM-3 and its ligands. Ligand-blocking anti-TIM-3 antibodies possess the potential to reactivate antigen-specific T cells and augment anti-tumor immunity. However, the precise ligand-receptor interactions disrupted by the administration of TIM-3 blocking Abs have yet to be fully elucidated. In this study, we have developed a panel of monoclonal antibodies targeting human TIM-3, namely MsT001, MsT065, MsT229, and MsT286. They exhibited high sensitivities (10 pg/mL) and affinities (3.70 × 10-9 to 4.61 × 10-11 M) for TIM-3. The TIM-3 antibodies recognized distinct epitopes, including linear epitopes (MsT001 and MsT065), and a conformational epitope (MsT229 and MsT286). Additionally, the MsT229 and MsT286 displayed reactivity towards cynomolgus TIM-3. The interactions between TIM-3/Gal-9, TIM-3/HMGB-1, and TIM-3/CEACAM-1 disrupt the binding of MsT229 and MsT286, while leaving the binding of MsT001 and MsT065 unaffected. The inhibitory effect on the interaction between Gal-9 and TIM-3 was found to be dose-dependently in the presence of either MsT229 or MsT286. The findings suggested that the involvement of conformational epitopes in TIM-3 is crucial for its interaction with ligands, and we successfully generated novel anti-TIM-3 Abs that exhibit inhibitory potential. In conclusion, our finding offers valuable insights -on the comprehension and targeting of human TIM-3.

The role of TIM-3 in sepsis: a promising target for immunotherapy?

Sepsis remains a significant cause of mortality and morbidity worldwide, with limited effective treatment options. The T-cell immunoglobulin and mucin domain-containing molecule 3 (TIM-3) has emerged as a potential therapeutic target in various immune-related disorders. This narrative review aims to explore the role of TIM-3 in sepsis and evaluate its potential as a promising target for immunotherapy. We discuss the dynamic expression patterns of TIM-3 during sepsis and its involvement in regulating immune responses. Furthermore, we examine the preclinical studies investigating the regulation of TIM-3 signaling pathways in septic models, highlighting the potential therapeutic benefits and challenges associated with targeting TIM-3. Overall, this review emphasizes the importance of TIM-3 in sepsis pathogenesis and underscores the promising prospects of TIM-3-based immunotherapy as a potential strategy to combat this life-threatening condition.

Overcoming cold tumors: a combination strategy of immune checkpoint inhibitors

Immune Checkpoint Inhibitors (ICIs) therapy has advanced significantly in treating malignant tumors, though most 'cold' tumors show no response. This resistance mainly arises from the varied immune evasion mechanisms. Hence, understanding the transformation from 'cold' to 'hot' tumors is essential in developing effective cancer treatments. Furthermore, tumor immune profiling is critical, requiring a range of diagnostic techniques and biomarkers for evaluation. The success of immunotherapy relies on T cells' ability to recognize and eliminate tumor cells. In 'cold' tumors, the absence of T cell infiltration leads to the ineffectiveness of ICI therapy. Addressing these challenges, especially the impairment in T cell activation and homing, is crucial to enhance ICI therapy's efficacy. Concurrently, strategies to convert 'cold' tumors into 'hot' ones, including boosting T cell infiltration and adoptive therapies such as T cell-recruiting bispecific antibodies and Chimeric Antigen Receptor (CAR) T cells, are under extensive exploration. Thus, identifying key factors that impact tumor T cell infiltration is vital for creating effective treatments targeting 'cold' tumors.

TIM-3/Galectin-9 interaction and glutamine metabolism in AML cell lines, HL-60 and THP-1

BACKGROUND

T cell immunoglobulin and mucin-domain containing-3 (TIM-3) is a cell surface molecule that was first discovered on T cells. However, recent studies revealed that it is also highly expressed in acute myeloid leukemia (AML) cells and it is related to AML progression. As, Glutamine appears to play a prominent role in malignant tumor progression, especially in their myeloid group, therefore, in this study we aimed to evaluate the relation between TIM-3/Galectin-9 axis and glutamine metabolism in two types of AML cell lines, HL-60 and THP-1.

METHODS

Cell lines were cultured in RPMI 1640 which supplemented with 10% FBS and 1% antibiotics. 24, 48, and 72 h after addition of recombinant Galectin-9 (Gal-9), RT-qPCR analysis, RP-HPLC and gas chromatography techniques were performed to evaluate the expression of glutaminase (GLS), glutamate dehydrogenase (GDH) enzymes, concentration of metabolites; Glutamate (Glu) and alpha-ketoglutarate (α-KG) in glutaminolysis pathway, respectively. Western blotting and MTT assay were used to detect expression of mammalian target of rapamycin complex (mTORC) as signaling factor, GLS protein and cell proliferation rate, respectively.

RESULTS

The most mRNA expression of GLS and GDH in HL-60 cells was seen at 72 h after Gal-9 treatment (p = 0.001, p = 0.0001) and in THP-1 cell line was observed at 24 h after Gal-9 addition (p = 0.001, p = 0.0001). The most mTORC and GLS protein expression in HL-60 and THP-1 cells was observed at 72 and 24 h after Gal-9 treatment (p = 0.0001), respectively. MTT assay revealed that Gal-9 could promote cell proliferation rate in both cell lines (p = 0.001). Glu concentration in HL-60 and α-KG concentration in both HL-60 (p = 0.03) and THP-1 (p = 0.0001) cell lines had a decreasing trend. But, Glu concentration had an increasing trend in THP-1 cell line (p = 0.0001).

CONCLUSION

Taken together, this study suggests TIM-3/Gal-9 interaction could promote glutamine metabolism in HL-60 and THP-1 cells and resulting in AML development.

Clinicopathological and prognostic significance of PD-L1 and TIM-3 expression in medullary thyroid carcinoma: a retrospective immunohistochemistry study

PURPOSE

Expression of the programmed death-ligand 1 (PD-L1) and T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) in medullary thyroid carcinoma (MTC) has been controversial and rarely reported.

METHODS

Surgical specimens of 190 MTC patients who had initial curative-intent surgery were collected. Immunohistochemistry of PD-L1 and TIM-3 was performed using 22C3 pharmDx (Dako, Carpinteria, CA) and anti-TIM-3 (1:500, ab241332, Abcam). Stained slides were scored using a combined positive score (CPS) with a cutoff of ≥ 1. We established correlations between PD-L1 expression, TIM-3 expression, clinicopathological, and survival data.

RESULTS

13 cases (13/190, 6.84%) were positive for PD-L1 expression, and 42 cases (42/154, 27.27%) for TIM-3 expression. PD-L1 expression was correlated to TIM-3 expression (P = 0.002), but was not related to overall survival (OS) or progression-free survival (PFS). TIM-3 expression was correlated to perineural invasion (P = 0.040). Multivariate Cox analysis showed that lymphovascular invasion (LVI) was independently associated with OS. And tumor size, LVI, and lymph node metastases were significantly associated with PFS. Furthermore, the multivariate logistic analysis showed multifocal status, LVI, pathological T stage and lymph node metastasis were independent risk factors for biochemical recurrence/persistent disease.

CONCLUSIONS

We demonstrated that PD-L1 and TIM-3 expression were not frequent in MTC and were not associated with survival prognosis. Our results should be considered when clinical trials of PD-L1 or TIM-3 blockades are implemented.

CAR-T-Cell Therapy Based on Immune Checkpoint Modulation in the Treatment of Hematologic Malignancies

Chimeric antigen receptor (CAR) T-cell therapy is a revolutionary immunotherapy that has shown significant success in treating certain hematologic malignancies. However, there are still challenges and limitations associated with this therapy, and not all cancer patients benefit from this therapy alone. Therefore, modifying CAR-T-cell therapy based on immune checkpoints, and its combination with immune checkpoint inhibitors (ICIs), shows promise as a potentially more effective strategy for treating hematologic malignancies. This article outlines the progress of preclinical and clinical trials of CAR-T-cell therapy based on immune checkpoint modulation in the treatment of hematologic malignancies.

Immune checkpoint expression patterns on T cell subsets in light-chain amyloidosis: VISTA, PD-1, and TIGIT as potential therapeutic targets

Amyloid light chain (AL) amyloidosis is a rare plasma cell dyscrasia with dismal prognosis. This study aims to investigate the T-cell immune checkpoint expression patterns in systemic AL amyloidosis and its relationship with clinicobiological traits. We examined the frequencies of V-domain immunoglobulin suppressor of T cell activation+ (VISTA+), programmed cell death 1+ (PD-1+), T cell immunoglobulin and mucin-domain-containing-3+ (Tim-3+), T cell immunoreceptor with Ig and ITIM domains+ (TIGIT+) T cells in peripheral blood (PB) and bone marrow (BM) from 19 patients with newly diagnosed AL amyloidosis. Patients with AL amyloidosis had significantly higher percentages of VISTA+ and PD-1+ T cells in PB than healthy individuals (HIs), with no statistical differences in BM. The percentages of some double-positive T cells in PB were also considerably higher in AL amyloidosis than those in HIs. Additionally, the patients with renal involvement had more PD-1+ and TIGIT+ T cells than the patients without, and PD-1+CD3+%, PD-1+CD4+%, PD-1+Treg% were positively correlated with 24-hour proteinuria levels. Furthermore, the AL amyloidosis patients had higher counts of PD-1+ Treg in PB than multiple myeloma (MM) patients, while the MM patients had higher counts of TIGIT+ T cells than AL amyloidosis patients. Collectively, this is the first report of elevated proportions of VISTA+ and PD-1+ T cells in PB of AL amyloidosis patients, indicating an immunosuppressive milieu, and the increased PD-1+ and TIGIT+ T cells were associated with renal damage. VISTA, PD-1, and TIGIT may be potential targets for reversing T-cell exhaustion in AL amyloidosis.

Microenvironment in acute myeloid leukemia: focus on senescence mechanisms, therapeutic interactions, and future directions

Acute myeloid leukemia (AML) is a disease with a dismal prognosis, mainly affecting the elderly. In recent years, new drugs have improved life expectancy and quality of life, and a better understanding of the genetic-molecular nature of the disease has shed light on previously unknown aspects of leukemogenesis. In parallel, increasing attention has been attracted to the complex interactions between cells and soluble factors in the bone marrow (BM) environment, collectively known as the microenvironment. In this review, we discuss the central role of the microenvironment in physiologic and pathologic hematopoiesis and the mechanisms of senescence, considered a fundamental protective mechanism against the proliferation of damaged and pretumoral cells. The microenvironment also represents a fertile ground for the development of myeloid malignancies, and the leukemic niche significantly interacts with drugs commonly used in AML treatment. Finally, we focus on the role of the microenvironment in the engraftment and complications of allogeneic hematopoietic stem cell transplantation, the only curative option in a conspicuous proportion of patients.

Higher PD-1/Tim-3 expression on IFN-γ+ T cells is associated with poor prognosis in patients with acute myeloid leukemia

With the success of immune checkpoint inhibitors (ICI), such as anti- programmed death-1 (PD-1) antibody for solid tumors and lymphoma immunotherapy, a number of clinical trials with ICIs have been attempted for acute myeloid leukemia (AML) immunotherapy; however, limited clinical efficacy has been reported. This may be due to the heterogeneity of immune microenvironments and various degrees of T cell exhaustion in patients and may be involved in the IFN-γ pathway. In this study, we first characterized the percentage of PD-1+ and T cell immunoglobulin mucin-domain-containing-3 (Tim-3) +IFN-γ+ T cells in peripheral blood (PB) in AML compared with healthy individuals (HIs) by flow cytometry and further discussed the possibility of the reversal of T cell exhaustion to restore the secretion capacity of cytokines in T cells in AML based on blockade of PD-1 or Tim-3 (anti-PD-1 and anti-Tim-3 antibody) in vitro using a cytokine protein chip. A significantly increased percentage of PD-1+, Tim-3+, and PD-1+Tim-3+ IFN-γ+ T cells was observed in PB from patients with AML in comparison with HIs. Moreover, higher PD-1+IFN-γ+CD3+/CD8+ T cell levels were associated with poor overall survival in AML patients. Regarding leukemia cells, the percentage of Tim-3 in CD117+CD34+ AML cells was positively correlated with PD-1 in IFN-γ+CD4+ T cells. Furthermore, blocking PD-1 and Tim-3 may involve multiple cytokines and helper T cell subsets, mainly Th1 and Treg cells. Blockade of PD-1 or Tim-3 tends to restore cytokine secretion to a certain extent, a synergistic effect shown by the co-blockade of PD-1 and Tim-3. However, we also demonstrated the heterogeneity of secretory cytokines in ICI-treated T cells in AML patients.

TIM-3/Gal-9 interaction affects glucose and lipid metabolism in acute myeloid leukemia cell lines

Introduction

T-cell immunoglobulin and mucin domain-3 (TIM-3) is a transmembrane molecule first identified as an immunoregulator. This molecule is also expressed on leukemic cells in acute myeloid leukemia and master cell survival and proliferation. In this study, we aimed to explore the effect of TIM-3 interaction with its ligand galectin-9 (Gal-9) on glucose and lipid metabolism in AML cell lines.

Methods

HL-60 and THP-1 cell lines, representing M3 and M5 AML subtypes, respectively, were cultured under appropriate conditions. The expression of TIM-3 on the cell surface was ascertained by flow cytometric assay. We used real-time PCR to examine the mRNA expression of GLUT-1, HK-2, PFKFB-3, G6PD, ACC-1, ATGL, and CPT-1A; colorimetric assays to measure the concentration of glucose, lactate, GSH, and the enzymatic activity of G6PD; MTT assay to determine cellular proliferation; and gas chromatography-mass spectrometry (GC-MS) to designate FFAs.

Results

We observed the significant upregulated expression of GLUT-1, HK-2, PFKFB-3, ACC-1, CPT-1A, and G6PD and the enzymatic activity of G6PD in a time-dependent manner in the presence of Gal-9 compared to the PMA and control groups in both HL-60 and THP-1 cell lines (p > 0.05). Moreover, the elevation of extracellular free fatty acids, glucose consumption, lactate release, the concentration of cellular glutathione (GSH) and cell proliferation were significantly higher in the presence of Gal-9 compared to the PMA and control groups in both cell lines (p < 0.05).

Conclusion

TIM-3/Gal-9 ligation on AML cell lines results in aerobic glycolysis and altered lipid metabolism and also protects cells from oxidative stress, all in favor of leukemic cell survival and proliferation.

Checkpoint inhibition in hematologic malignancies

Checkpoint inhibitor therapy has emerged as an effective therapeutic strategy for many types of malignancies, especially in solid tumors. Within the last two decades, numerous monoclonal antibody drugs targeting the CTLA-4 and PD-1/PD-L1 checkpoint pathways have seen FDA approval. Within hematologic malignancies, Hodgkin Lymphoma has seen the greatest clinical benefits thus far with more recent data showing efficacy in the front-line setting. As our understanding of checkpoint inhibition expands, using these pathways as a therapeutic target has shown some utility in the treatment of other hematologic malignancies as well, primarily in the relapsed/refractory settings. Checkpoint inhibition also appears to have a role as a synergistic agent to augment clinical responses to other forms of therapy such as hematopoietic stem cell transplant. Moreover, alternative checkpoint molecules that bypass the well-studied CTLA-4 and PD-1/PD-L1 pathways have emerged as exciting new therapeutic targets. Most excitingly is the use of anti-CD47 blockade in the treatment of high risk MDS and TP-53 mutated AML. Overall, there has been tremendous progress in understanding the benefits of checkpoint inhibition in hematologic malignancies, but further studies are needed in all areas to best utilize these agents. This is a review of the most recent developments and progress in Immune Checkpoint Inhibition in Hematologic Malignancies in the last decade.

The role of bone marrow microenvironment (BMM) cells in acute myeloid leukemia (AML) progression: immune checkpoints, metabolic checkpoints, and signaling pathways

Acute myeloid leukemia (AML) comprises a multifarious and heterogeneous array of illnesses characterized by the anomalous proliferation of myeloid cells in the bone marrow microenvironment (BMM). The BMM plays a pivotal role in promoting AML progression, angiogenesis, and metastasis. The immune checkpoints (ICs) and metabolic processes are the key players in this process. In this review, we delineate the metabolic and immune checkpoint characteristics of the AML BMM, with a focus on the roles of BMM cells e.g. tumor-associated macrophages, natural killer cells, dendritic cells, metabolic profiles and related signaling pathways. We also discuss the signaling pathways stimulated in AML cells by BMM factors that lead to AML progression. We then delve into the roles of immune checkpoints in AML angiogenesis, metastasis, and cell proliferation, including co-stimulatory and inhibitory ICs. Lastly, we discuss the potential therapeutic approaches and future directions for AML treatment, emphasizing the potential of targeting metabolic and immune checkpoints in AML BMM as prognostic and therapeutic targets. In conclusion, the modulation of these processes through the use of directed drugs opens up new promising avenues in combating AML. Thereby, a comprehensive elucidation of the significance of these AML BMM cells' metabolic and immune checkpoints and signaling pathways on leukemic cells can be undertaken in the future investigations. Additionally, these checkpoints and cells should be considered plausible multi-targeted therapies for AML in combination with other conventional treatments in AML. Video Abstract.

Immunotherapy in leukaemia

Leukaemia is the common name for a group of malignant diseases of the haematopoietic system with complex classifications and characteristics. Remarkable progress has been made in basic research and preclinical studies for acute leukaemia compared to that of the many other types/subtypes of leukaemia, especially the exploration of the biological basis and application of immunotherapy in acute myeloid leukaemia (AML) and B-cell acute lymphoblastic leukaemia (B-ALL). In this review, we summarize the basic approaches to immunotherapy for leukaemia and focus on the research progress made in immunotherapy development for AML and ALL. Importantly, despite the advances made to date, big challenges still exist in the effectiveness of leukaemia immunotherapy, especially in AML. Therefore, we use AML as an example and summarize the mechanisms of tumour cell immune evasion, describe recently reported data and known therapeutic targets, and discuss the obstacles in finding suitable treatment targets and the results obtained in recent clinical trials for several types of single and combination immunotherapies, such as bispecific antibodies, cell therapies (CAR-T-cell treatment), and checkpoint blockade. Finally, we summarize novel immunotherapy strategies for treating lymphocytic leukaemia and clinical trial results.

Recent Advances in Molecular Mechanisms of Cancer Immunotherapy

Cancer is among the current leading causes of death worldwide, despite the novel advances that have been made toward its treatment, it is still considered a major public health concern. Considering both the serious impact of cancer on public health and the significant side effects and complications of conventional therapeutic options, the current strategies towards targeted cancer therapy must be enhanced to avoid undesired toxicity. Cancer immunotherapy has become preferable among researchers in recent years compared to conventional therapeutic options, such as chemotherapy, surgery, and radiotherapy. The understanding of how to control immune checkpoints, develop therapeutic cancer vaccines, genetically modify immune cells as well as enhance the activation of antitumor immune response led to the development of novel cancer treatments. In this review, we address recent advances in cancer immunotherapy molecular mechanisms. Different immunotherapeutic approaches are critically discussed, focusing on the challenges, potential risks, and prospects involving their use.

The Bone Marrow Immune Microenvironment in CML: Treatment Responses, Treatment-Free Remission, and Therapeutic Vulnerabilities

PURPOSE OF REVIEW

Tyrosine kinase inhibitors (TKIs) are very successful for the treatment of chronic myeloid leukaemia (CML) but are not curative in most patients due to persistence of TKI-resistant leukaemia stem cells (LSCs). The bone marrow immune microenvironment (BME) provides protection to the LSC through multidimensional interactions, driving therapy resistance, and highlighting the need to circumvent these protective niches therapeutically. This review updates the evidence for interactions between CML cells and the immune microenvironment with a view to identifying targetable therapeutic vulnerabilities and describes what is known about the role of immune regulation in treatment-free remission (TFR).

RECENT FINDINGS

Intracellular signalling downstream of the chemotactic CXCL12-CXCR4 axis, responsible for disrupted homing in CML, has been elucidated in LSCs, highlighting novel therapeutic opportunities. In addition, LSCs expressing CXCL12-cleaving surface protein CD26 were highly correlated with CML burden, building on existing evidence. Newer findings implicate the adhesion molecule CD44 in TKI resistance, while JAK/STAT-mediated resistance to TKIs may occur downstream of extrinsic signalling in the BME. Exosomal BME-LSC cross-communication has also been explored. Finally, further detail on the phenotypes of natural killer (NK) cells putatively involved in maintaining successful TFR has been published, and NK-based immunotherapies are discussed. Recent studies highlight and build on our understanding of the BME in CML persistence and TKI resistance, pinpointing therapeutically vulnerable interactions. Repurposing existing drugs and/or the development of novel inhibitors targeting these relationships may help to overcome these issues in TKI-resistant CML and be used as adjuvant therapy for sustained TFR.

Immune Checkpoints and targeted agents in relapse and graft-versus-host disease after hematopoietic stem cell transplantation

BACKGROUND

Allogeneic hematopoietic stem cell transplantation (HSCT) is a potentially curative therapy for malignant hematologic disorders. Novel anti-infection agents have successfully decreased the risk of fatal infections post-HSCT in recent years, but the relapse of primary disease and graft-versus-host disease (GVHD) remain the major causes of death for transplant recipients, and significantly deteriorate the quality of life. Thus, it is crucial to maintain the immune homeostasis in transplant recipients and balance the graft-versus-leukemia (GVL) effect and GVHD.

METHODS

We reviewed the recently published literatures on immune checkpoint (IC) and targeted agents in relapse and GVHD after allogeneic HSCT RESULTS: Emerging data suggest that IC is an attractive target to modulate immune responses, and accumulating evidences of IC-targeted agents have been published for the treatment of malignancies and autoimmune disorders. The unique mechanism of IC-targeted agents, which affects the immune homeostasis of the transplant recipient by modulating alloreactivity, minimizes the risk of organ toxicity and immunosuppression associated with conventional therapy CONCLUSION: There is an increase in literature reporting the application of immune checkpoint-targeted agents in HSCT settings, and an overview will benefit further exploration in this field.

Soluble TIM-3 as a biomarker of progression and therapeutic response in cancers and other of human diseases

Immune checkpoints inhibition is a privileged approach to combat cancers and other human diseases. The TIM-3 (T cell immunoglobulin and mucin-domain containing-3) inhibitory checkpoint expressed on different types of immune cells is actively investigated as an anticancer target, with a dozen of monoclonal antibodies in (pre)clinical development. A soluble form sTIM-3 can be found in the plasma of patients with cancer and other diseases. This active circulating protein originates from the proteolytic cleavage by two ADAM metalloproteases of the membrane receptor shared by tumor and non-tumor cells, and extracellular vesicles. In most cancers but not all, overexpression of mTIM-3 at the cell surface leads to high level of sTIM-3. Similarly, elevated levels of sTIM-3 have been reported in chronic autoimmune diseases, inflammatory gastro-intestinal diseases, certain viral and parasitic diseases, but also in cases of organ transplantation and in pregnancy-related pathologies. We have analyzed the origin of sTIM-3, its methods of dosage in blood or plasma, its presence in multiple diseases and its potential role as a biomarker to follow disease progression and/or the treatment response. In contrast to sPD-L1 generated by different classes of proteases and by alternative splicing, sTIM-3 is uniquely produced upon ADAM-dependent shedding, providing a more homogenous molecular entity and a possibly more reliable molecular marker. However, the biological functionality of sTIM-3 remains insufficiently characterized. The review shed light on pathologies associated with an altered expression of sTIM-3 in human plasma and the possibility to use sTIM-3 as a diagnostic or therapeutic marker.

Contribution of the TIM-3/Gal-9 immune checkpoint to tropical parasitic diseases

Neglected tropical parasitic diseases (NTD) are prevalent in many countries and cost-effective treatments remain urgently needed. Novel approaches have been proposed to address these diseases through an action on immune co-inhibitory checkpoints which are exploited by parasites to evade the immune system. Among these checkpoints, TIM-3 has been shown to play a key role in antiparasitic immunity via a repression and functional attenuation of CD4⁺ and/or CD8⁺ T-cells. The present review discusses the role of the TIM-3/galectin-9 checkpoint in seven major NTD: Chagas disease, leishmaniasis and malaria (3 trypanosomatid infections), schistosomiasis, toxoplasmosis, echinococcosis and filariasis (4 helminth infections). In each case, the role of the checkpoint has been analyzed and the use of anti-TIM-3 antibodies evaluated as a potential therapeutic approach. In general, the parasitic infection is coupled with an upregulation of TIM-3 expressed on T cells, but not necessarily with an exhaustion of those T cells. In several cases, the use of anti-TIM-3 antibodies represent a possible strategy to reinforce the clearance and to reduce the parasite load. Promising data have been reported in cases of leishmaniasis, malaria and schistosomiasis, whereas a similar approach proved much less efficient (if not deleterious) in cases of echinococcosis and the Chagas disease. Nevertheless, the TIM-3 checkpoint warrants further consideration as a potential immune target to combat these pathologies, using antibodies or drugs capable of reducing directly or indirectly the expression and function of the checkpoint, to restore an immune control.

Mucin (MUC) Family Influence on Acute Lymphoblastic Leukemia in Cancer and Non-Cancer Native American Populations from the Brazilian Amazon

The mucin (MUC) family includes several genes aberrantly expressed in multiple carcinomas and mediates diverse pathways essentials for oncogenesis, in both solid and hematological malignancies. Acute Lymphoblastic Leukemia (ALL) can have its course influenced by genetic variants, and it seems more frequent in the Amerindian population, which has been understudied. Therefore, the present work aimed to investigate the MUC family exome in Amerindian individuals from the Brazilian Amazon, in a sample containing healthy Native Americans (NAMs) and indigenous subjects with ALL, comparing the frequency of polymorphisms between these two groups. The population was composed of 64 Amerindians from the Brazilian Amazon, from 12 different isolated tribes, five of whom were diagnosed with ALL. We analyzed 16 genes from the MUC family and found a total of 1858 variants. We compared the frequency of each variant in the ALL vs. NAM group, which led to 77 variants with a significant difference and, among these, we excluded those with a low impact, resulting in 63 variants, which were distributed in nine genes, concentrated especially in MUC 19 (n = 30) and MUC 3A (n = 18). Finally, 11 new variants were found in the NAM population. This is the first work with a sample of native Americans with cancer, a population which is susceptible to ALL, but remains understudied. The MUC family seems to have an influence on the development of ALL in the Amerindian population and especially MUC19 and MUC3A are shown as possible hotspots. In addition, the 11 new variants found point to the need to have their clinical impact analyzed.

Characterizing and correcting immune dysfunction in non-tuberculous mycobacterial disease

Non-tuberculous mycobacterial pulmonary disease (NTM-PD) is a chronic, progressive, and growing worldwide health burden associated with mounting morbidity, mortality, and economic costs. Improvements in NTM-PD management are urgently needed, which requires a better understanding of fundamental immunopathology. Here, we examine temporal dynamics of the immune compartment during NTM-PD caused by Mycobacterium avium complex (MAC) and Mycobactereoides abscessus complex (MABS). We show that active MAC infection is characterized by elevated T cell immunoglobulin and mucin-domain containing-3 expression across multiple T cell subsets. In contrast, active MABS infection was characterized by increased expression of cytotoxic T-lymphocyte-associated protein 4. Patients who failed therapy closely mirrored the healthy individual immune phenotype, with circulating immune network appearing to 'ignore' infection in the lung. Interestingly, immune biosignatures were identified that could inform disease stage and infecting species with high accuracy. Additionally, programmed cell death protein 1 blockade rescued antigen-specific IFN-γ secretion in all disease stages except persistent infection, suggesting the potential to redeploy checkpoint blockade inhibitors for NTM-PD. Collectively, our results provide new insight into species-specific 'immune chatter' occurring during NTM-PD and provide new targets, processes and pathways for diagnostics, prognostics, and treatments needed for this emerging and difficult to treat disease.

Immune checkpoint alterations and their blockade in COVID-19 patients

Coronavirus disease 2019 (COVID-19) is a highly contagious disease that seriously affects people's lives. Immune dysfunction, which is characterized by abnormal expression of multiple immune checkpoint proteins (ICs) on immune cells, is associated with progression and poor prognosis for tumors and chronic infections. Immunotherapy targeting ICs has been well established in modulating immune function and improving clinical outcome for solid tumors and hematological malignancies. The role of ICs in different populations or COVID-19 stages and the impact of IC blockade remains unclear. In this review, we summarized current studies of alterations in ICs in COVID-19 to better understand immune changes and provide strategies for treating COVID-19 patients, particularly those with cancer.

Recent Advances and Challenges in Cancer Immunotherapy

Simple Summary

Immunotherapy helps a person’s immune system to target tumor cells. Recent advances in cancer immunotherapy, including immune checkpoint inhibition, chimeric antigen receptor T-cell therapy and cancer vaccination, have changed the landscape of cancer treatment. These approaches have had profound success in certain cancer types but still fail in the majority of cases. This review will cover both successes and current challenges in cancer immunotherapy, as well as recent advances in the field of basic tumor immunology that will allow us to overcome resistance to existing treatments.

Abstract

Cancer immunotherapy has revolutionized the field of oncology in recent years. Harnessing the immune system to treat cancer has led to a large growth in the number of novel immunotherapeutic strategies, including immune checkpoint inhibition, chimeric antigen receptor T-cell therapy and cancer vaccination. In this review, we will discuss the current landscape of immuno-oncology research, with a focus on elements that influence immunotherapeutic outcomes. We will also highlight recent advances in basic aspects of tumor immunology, in particular, the role of the immunosuppressive cells within the tumor microenvironment in regulating antitumor immunity. Lastly, we will discuss how the understanding of basic tumor immunology can lead to the development of new immunotherapeutic strategies.

BET bromodomain inhibition rescues PD-1-mediated T-cell exhaustion in acute myeloid leukemia

Sustained expression of programmed cell death receptor-1 (PD-1) is correlated with the exhaustion of T cells, and blockade of the PD-1 pathway is an effective immunotherapeutic strategy for treating various cancers. However, response rates are limited, and many patients do not achieve durable responses. Thus, it is important to seek additional strategies that can improve anticancer immunity. Here, we report that the bromodomain and extraterminal domain (BET) inhibitor JQ1 inhibits PD-1 expression in Jurkat T cells, primary T cells, and T-cell exhaustion models. Furthermore, JQ1 dramatically impaired the expression of PD-1 and T-cell immunoglobulin mucin-domain-containing-3 (Tim-3) and promoted the secretion of cytokines in T cells from patients with acute myeloid leukemia (AML). In line with that, BET inhibitor-treated CD19-CAR T and CD123-CAR T cells have enhanced anti-leukemia potency and resistant to exhaustion. Mechanistically, BRD4 binds to the NFAT2 and PDCD1 (encoding PD-1) promoters, and NFAT2 binds to the PDCD1 and HAVCR2 (encoding Tim-3) promoters. JQ1-treated T cells showed downregulated NFAT2, PD-1, and Tim-3 expression. In addition, BET inhibitor suppressed programmed death-ligand 1 (PD-L1) expression and cell growth in AML cell lines and in primary AML cells. We also demonstrated that JQ1 treatment led to inhibition of leukemia progression, reduced T-cell PD-1/Tim-3 expression, and prolonged survival in MLL-AF9 AML mouse model and Nalm6 (B-cell acute lymphoblastic leukemia cell)-bearing mouse leukemia model. Taken together, BET inhibition improved anti-leukemia immunity by regulating PD-1/PD-L1 expression, and also directly suppressed AML cells, which provides novel insights on the multiple effects of BET inhibition for cancer therapy.

Current insight into the regulation of PD-L1 in cancer

The molecular mechanisms underlying cancer immune escape are a core topic in cancer immunology research. Cancer cells can escape T cell-mediated cellular cytotoxicity by exploiting the inhibitory programmed cell-death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1, CD274) immune checkpoint. Studying the PD-L1 regulatory pattern of tumor cells will help elucidate the molecular mechanisms of tumor immune evasion and improve cancer treatment. Recent studies have found that tumor cells regulate PD-L1 at the transcriptional, post-transcriptional, and post-translational levels and influence the anti-tumor immune response by regulating PD-L1. In this review, we focus on the regulation of PD-L1 in cancer cells and summarize the underlying mechanisms.

Extracellular vesicles in pancreatic cancer immune escape: Emerging roles and mechanisms

Pancreatic cancer (PC) is the most lethal malignancy worldwide due to its delayed diagnosis and limited treatment options. Despite great progress in clinical trials of immunotherapies for various cancers, their effectiveness in PC is very low, indicating that immune evasion is still a major obstacle to immunotherapy in PC. However, the mechanism of immune escape in PC is not fully understood, which substantially restricts the development of immunotherapy. As an important component of intercellular communication networks, extracellular vesicles (EVs) have attracted increasing attention in relation to immune escape. This review aims to provide a better understanding of the roles of EVs in tumor immune escape and the potential to expand their application in cancer immunotherapy. The relationship between PC and the tumor immune microenvironment is briefly introduced. Then, the mechanism by which EVs are involved in immune regulation is summarized, and the latest progress in determining the role of EVs in regulating PC immune escape is highlighted.

Tumor Microenvironment in Acute Myeloid Leukemia: Adjusting Niches

Acute myeloid leukemias (AML) comprise a wide array of different entities, which have in common a rapid expansion of myeloid blast cells leading to displacement of normal hematopoietic cells and also disruption of the microenvironment in the bone marrow niches. Based on an insight into the complex cellular interactions in the bone marrow niches in non-neoplastic conditions in general, this review delineates the complex relationship between leukemic cells and reactive cells of the tumor microenvironment (TME) in AML. A special focus is directed on niche cells and various T-cell subsets as these also provide a potential therapeutic rationale considering e.g. immunomodulation. The TME of AML on the one hand plays a vital role for sustaining and promoting leukemogenesis but - on the other hand - it also has adverse effects on abnormal blasts developing into overt leukemia hindering their proliferation and potentially removing such cells. Thus, leukemic cells need to and develop strategies in order to manipulate the TME. Interference with those strategies might be of particular therapeutic potential since mechanisms of resistance related to tumor cell plasticity do not apply to it.

Design and Evaluation of TIM-3-CD28 Checkpoint Fusion Proteins to Improve Anti-CD19 CAR T-Cell Function

Therapeutic targeting of inhibitory checkpoint molecules in combination with chimeric antigen receptor (CAR) T cells is currently investigated in a variety of clinical studies for treatment of hematologic and solid malignancies. However, the impact of co-inhibitory axes and their therapeutic implication remains understudied for the majority of acute leukemias due to their low immunogenicity/mutational load. The inhibitory exhaustion molecule TIM-3 is an important marker for the interaction of T cells with leukemic cells. Moreover, inhibitory signals from malignant cells could be transformed into stimulatory signals by synthetic fusion molecules with extracellular inhibitory receptors fused to an intracellular stimulatory domain. Here, we designed a variety of different TIM-3-CD28 fusion proteins to turn inhibitory signals derived by TIM-3 engagement into T-cell activation through CD28. In the absence of anti-CD19 CAR, two TIM-3-CD28 fusion receptors with large parts of CD28 showed strongest responses in terms of cytokine secretion and proliferation upon stimulation with anti-CD3 antibodies compared to controls. We then combined these two novel TIM-3-CD28 fusion proteins with first- and second-generation anti-CD19 CAR T cells and found that the fusion receptor can increase proliferation, activation, and cytotoxic capacity of conventional anti-CD19 CAR T cells. These additionally armed CAR T cells showed excellent effector function. In terms of safety considerations, the fusion receptors showed exclusively increased cytokine release, when the CAR target CD19 was present. We conclude that combining checkpoint fusion proteins with anti-CD19 CARs has the potential to increase T-cell proliferation capacity with the intention to overcome inhibitory signals during the response against malignant cells.

New Approaches to Myelodysplastic Syndrome Treatment

OPINION STATEMENT

The treatment of myelodysplastic syndromes (MDS) begins with risk stratification using a validated tool such as the International Prognostic Scoring System (IPSS) or its revised version (IPSS-R). This divides patients into lower- and higher- risk categories. Although treatment objectives in lower-risk MDS (LR-MDS) have traditionally been directed at improving cytopenias (usually anemia) as well as quality of life, recent data supports a potential role for early intervention in delaying transfusion dependency. In addition, careful individualized risk stratification incorporating clinical, cytogenetic, and mutational data might help identify patients at higher-than-expected risk for progression. Given the need for supportive care with red blood cell (RBC) transfusions leading to iron overload, iron chelation should be considered for patients with heavy transfusion requirements at risk for end-organ complications. For patients with LR-MDS and isolated anemia, no high-risk features, and endogenous erythropoietin (EPO) levels below 500 U/L, erythropoiesis-stimulating agents (ESAs) can be attempted to improve anemia. Some LR-MDS patient subgroups may also benefit from specific therapies including luspatercept (MDS with ring sideroblasts), lenalidomide (MDS with deletion 5q), or immunosuppressive therapy (hypocellular MDS). LR-MDS patients failing the above options, or those with multiple cytopenias and/or higher-risk features, can be considered for oral low-dose hypomethylating agent (HMA) therapy. Alternatively, these patients may be enrolled on a clinical trial with promising agents targeting the transforming-growth factor beta (TGF-β) pathway, the hypoxia-inducible factor (HIF) pathway, telomerase activity, inflammatory signaling, or the splicing machinery. In higher-risk MDS (HR-MDS), therapy seeks to modify the natural history of the disease and prolong survival. Eligible patients should be considered for curative allogeneic hematopoietic stem cell transplantation (aHSCT). Despite promising novel combinations, the HMAs azacitidine (AZA) or decitabine (DAC) are still the standard of care for these patients, with intensive chemotherapy-based approaches being a potential option in a small subset of patients. Individuals who fail to respond or progress after HMA experience dismal outcomes and represent a major unmet clinical need. Such patients should be treated as part of a clinical trial if possible. Experimental agents to consider include venetoclax, myeloid cell leukemia 1 (MCL-1) inhibitors, eprenetapopt, CPX-351, immunotherapies (directed towards CD47, TIM3, or CD70), interleukin-1 receptor-associated kinase 4 (IRAK4) inhibitors, pevonedistat, seclidemstat, and eltanexor. In this review, we extensively discuss the current landscape of experimental therapies for both LR- and HR-MDS.

Mesothelin: An Immunotherapeutic Target beyond Solid Tumors

Simple Summary

This review summarizes the current knowledge on mesothelin’s function, its role in cancer, and opportunities for immunotherapeutic targeting of mesothelin. Immunotherapies including monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK-cells, targeted alpha therapies, and bispecific T cell engaging molecules are reviewed. We show future directions for mesothelin targeting in hematological malignancies, including acute myeloid leukemia.

Abstract

Modern targeted cancer therapies rely on the overexpression of tumor associated antigens with very little to no expression in normal cell types. Mesothelin is a glycosylphosphatidylinositol-anchored cell surface protein that has been identified in many different tumor types, including lung adenocarcinomas, ovarian carcinomas, and most recently in hematological malignancies, including acute myeloid leukemia (AML). Although the function of mesothelin is widely unknown, interactions with MUC16/CA125 indicate that mesothelin plays a role in the regulation of proliferation, growth, and adhesion signaling. Most research on mesothelin currently focuses on utilizing mesothelin to design targeted cancer therapies such as monoclonal antibodies, antibody–drug conjugates, chimeric antigen receptor T and NK cells, bispecific T cell engaging molecules, and targeted alpha therapies, amongst others. Both in vitro and in vivo studies using different immunotherapeutic modalities in mesothelin-positive AML models highlight the potential impact of this approach as a unique opportunity to treat hard-to-cure AML.

Modulation of the Gal-9/TIM-3 Immune Checkpoint with α-Lactose. Does Anomery of Lactose Matter?

Simple Summary

The disaccharide lactose is a common excipient in pharmaceutical products. In addition, the two anomers α- and β-lactose can exert immuno-modulatory effects. α-Lactose functions as a major regulator of the T-cell immunoglobulin mucin-3 (Tim-3)/Galectin-9 (Gal-9) immune checkpoint, through direct binding to the β-galactoside-binding lectin galectin-9. The blockade of TIM-3 with monoclonal antibodies or small molecules represents a promising approach to combat onco-hematological diseases, in particular myelodysplastic syndromes, and acute myeloid leukemia. Alternatively, the activity of the checkpoint can be modulated via targeting of Gal-9 with both α- and β-lactose. In fact, lactose is a quasi-pan-galectin ligand, capable of modulating the functions of most of the 16 galectin molecules. This review discusses the capacity of lactose and Gal-9 to modulate the TIM-3/Gal-9 and PD-1/PD-L1 immune checkpoints in oncology. The immuno-regulatory roles of lactose and Gal-9 are highlighted.

Abstract

The disaccharide lactose is an excipient commonly used in pharmaceutical products. The two anomers, α- and β-lactose (α-L/β-L), differ by the orientation of the C-1 hydroxyl group on the glucose unit. In aqueous solution, a mutarotation process leads to an equilibrium of about 40% α-L and 60% β-L at room temperature. Beyond a pharmaceutical excipient in solid products, α-L has immuno-modulatory effects and functions as a major regulator of TIM-3/Gal-9 immune checkpoint, through direct binding to the β-galactoside-binding lectin galectin-9. The blockade of the co-inhibitory checkpoint TIM-3 expressed on T cells with anti-TIM-3 antibodies represents a promising approach to combat different onco-hematological diseases, in particular myelodysplastic syndromes and acute myeloid leukemia. In parallel, the discovery and development of anti-TIM-3 small molecule ligands is emerging, including peptides, RNA aptamers and a few specifically designed heterocyclic molecules. An alternative option consists of targeting the different ligands of TIM-3, notably Gal-9 recognized by α-lactose. Modulation of the TIM-3/Gal-9 checkpoint can be achieved with both α- and β-lactose. Moreover, lactose is a quasi-pan-galectin ligand, capable of modulating the functions of most of the 16 galectin molecules. The present review provides a complete analysis of the pharmaceutical and galectin-related biological functions of (α/β)-lactose. A focus is made on the capacity of lactose and Gal-9 to modulate both the TIM-3/Gal-9 and PD-1/PD-L1 immune checkpoints in oncology. Modulation of the TIM-3/Gal-9 checkpoint is a promising approach for the treatment of cancers and the role of lactose in this context is discussed. The review highlights the immuno-regulatory functions of lactose, and the benefit of the molecule well beyond its use as a pharmaceutical excipient.