scholarly journals T cell–induced CSF1 promotes melanoma resistance to PD1 blockade

2018 ◽  
Vol 10 (436) ◽  
pp. eaan3311 ◽  
Author(s):  
Natalie J. Neubert ◽  
Martina Schmittnaegel ◽  
Natacha Bordry ◽  
Sina Nassiri ◽  
Noémie Wald ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Resistance Mechanism ◽  
Immune Checkpoint Blockade ◽  
Human Melanoma ◽  
Checkpoint Blockade ◽  
Data Sets ◽  
Adaptive Resistance ◽  
Pd1 Blockade

Colony-stimulating factor 1 (CSF1) is a key regulator of monocyte/macrophage differentiation that sustains the protumorigenic functions of tumor-associated macrophages (TAMs). We show that CSF1 is expressed in human melanoma, and patients with metastatic melanoma have increased CSF1 in blood compared to healthy subjects. In tumors, CSF1 expression correlated with the abundance of CD8+T cells and CD163+TAMs. Human melanoma cell lines consistently produced CSF1 after exposure to melanoma-specific CD8+T cells or T cell–derived cytokines in vitro, reflecting a broadly conserved mechanism of CSF1 induction by activated CD8+T cells. Mining of publicly available transcriptomic data sets suggested co-enrichment of CD8+T cells with CSF1 or various TAM-specific markers in human melanoma, which was associated with nonresponsiveness to programmed cell death protein 1 (PD1) checkpoint blockade in a smaller patient cohort. Combination of anti-PD1 and anti–CSF1 receptor (CSF1R) antibodies induced the regression ofBRAFV600E-driven, transplant mouse melanomas, a result that was dependent on the effective elimination of TAMs. Collectively, these data implicate CSF1 induction as a CD8+T cell–dependent adaptive resistance mechanism and show that simultaneous CSF1R targeting may be beneficial in melanomas refractory to immune checkpoint blockade and, possibly, other T cell–based therapies.

scholarly journals Metabolomic adaptations and correlates of survival to immune checkpoint blockade

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Haoxin Li ◽  
Kevin Bullock ◽  
Carino Gurjao ◽  
David Braun ◽  
Sachet A. Shukla ◽  
...  
Keyword(s):  
Immune Checkpoint ◽  
Checkpoint Inhibitors ◽  
Resistance Mechanism ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
Adaptive Resistance ◽  
Metabolic Monitoring ◽  
Pd1 Blockade ◽  
To Receive ◽  
Cell Death Protein

Abstract Despite remarkable success of immune checkpoint inhibitors, the majority of cancer patients have yet to receive durable benefits. Here, in order to investigate the metabolic alterations in response to immune checkpoint blockade, we comprehensively profile serum metabolites in advanced melanoma and renal cell carcinoma patients treated with nivolumab, an antibody against programmed cell death protein 1 (PD1). We identify serum kynurenine/tryptophan ratio increases as an adaptive resistance mechanism associated with worse overall survival. This advocates for patient stratification and metabolic monitoring in immunotherapy clinical trials including those combining PD1 blockade with indoleamine 2,3-dioxygenase/tryptophan 2,3-dioxygenase   (IDO/TDO) inhibitors.

scholarly journals B cells sustain inflammation and predict response to immune checkpoint blockade in human melanoma

2018 ◽  
Author(s):  
Johannes Griss ◽  
Wolfgang Bauer ◽  
Christine Wagner ◽  
Margarita Maurer-Granofszky ◽  
Martin Simon ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
Immune Checkpoint ◽  
Cd8 T Cell ◽  
Immune Checkpoint Blockade ◽  
Human Melanoma ◽  
Checkpoint Blockade ◽  
Inflammatory Factors ◽  
T Effector Cells

Tumor associated inflammation predicts response to immune checkpoint blockade in human melanoma. Established mechanisms that underlie therapy response and resistance center on anti-tumor T cell responses. Here we show that tumor-associated B cells are vital to tumor associated inflammation. Autologous B cells were directly induced by melanoma conditioned medium, expressed pro- and anti-inflammatory factors, and differentiated towards a plasmablast-like phenotype in vitro. We could identify this phenotype as a distinct cluster of B cells in an independent public single-cell RNA-seq dataset from melanoma tumors. There, plasmablast-like tumor-associated B cells showed expression of CD8+T cell-recruiting chemokines such as CCL3, CCL4, CCL5 and CCL28. Depletion of tumor associated B cells in metastatic melanoma patients by anti-CD20 immunotherapy decreased overall inflammation and CD8+T cell numbers in the human melanoma TME. Conversely, the frequency of plasmablast-like B cells in pretherapy melanoma samples predicted response and survival to immune checkpoint blockade in two independent cohorts. Tumor-associated B cells therefore orchestrate and sustain tumor inflammation, recruit CD8+ T effector cells and may represent a predictor for response and survival to immune checkpoint blockade in human melanoma.

scholarly journals IMMU-27. IMMUNE CHECKPOINT BLOCKADE OF EX VIVO EXPANDED T CELLS FOR USE IN ADOPTIVE CELLULAR THERAPY (ACT) FOR GLIOBLASTOMA

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi124-vi125
Author(s):  
Elizabeth Ogando-Rivas ◽  
Changlin Yang ◽  
Paul Castillo ◽  
Anjelika Dechkovskaia ◽  
Duane Mitchell
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Immune Checkpoint ◽  
Cellular Therapy ◽  
Ex Vivo ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
Study Objective

Abstract BACKGROUND Despite aggressive treatments, GBM continues to have unacceptably high mortality rates. Immune-checkpoint blockade and ACT have shown excellent results in other solid tumors, especially in melanoma. Unfortunately, these results have not been extrapolated to GBM. We have developed a novel platform for ACT using tumor mRNA-pulsed dendritic cells(DCs) to in-vitro expand polyclonal populations of tumor-reactive T-cells. This platform has shown promising effects in preclinical brain tumor models (Flores et al OncoImmunology 2015, Wildes et al CCR 2018, Flores et al NatureComm 2018) and being evaluated in clinical trials at UF Health (NCT02465268,NCT03334305). STUDY OBJECTIVE Evaluate whether immune-checkpoint blockade during ex-vivo expansion of antigen-specific T-cells impact their use in ACT. METHODS CMVpp65 was used as model antigen for in-vitro activation of T-cells. Mature pp65 mRNA-pulsed DCs from CMV+ healthy donors were co-cultured with T-cells in IL2-containing medium for 15days. We tested four checkpoint inhibitor groups: PD1(n= 6), PDL1(n= 4), TIM3(n= 7) and PD1+TIM3(n= 6) that were compared with non-blockade group, respectively. Checkpoint blockade was performed every 3days. T-cell proliferation, immune-phenotyping, and IFN-g release were analyzed. RESULTS Cell proliferation was lower in all the blockade groups but significantly lower in the TIM3 (p= 0.03) and TIM3+PD1 (p= 0.01) blockade groups. TIM3 expression was significantly lower in the TIM3 (p= 0.006) and PD1+TIM3 blockade groups (p= 0.0001). There was a trend of reduced pp65 tetramer positive in the TIM3 and PD1+TIM3 blockade groups (PD1+TIM3 subgroup at 3mcg/mL, p= 0.02) and lower INFg release in the TIM3 and PD1+TIM3 blockade groups. CONCLUSION The exact role of checkpoints during expansion of T-cells for ACT is not well understood. In our study checkpoint blockade with PD-1 or TIM-3 alone or in combination did not enhance T-cell expansion or function, in fact, appeared to have an inhibitory effect on measured parameters. Our results suggest that TIM-3 may have an activating role in our system.

scholarly journals B cells sustain inflammation and predict response to immune checkpoint blockade in human melanoma

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Johannes Griss ◽  
Wolfgang Bauer ◽  
Christine Wagner ◽  
Martin Simon ◽  
Minyi Chen ◽  
...  
Keyword(s):  
T Cell ◽  
B Cells ◽  
T Cell Activation ◽  
Immune Checkpoint ◽  
Cell Activation ◽  
Immune Checkpoint Blockade ◽  
Human Melanoma ◽  
Checkpoint Blockade ◽  
Inflammatory Factors

Abstract Tumor associated inflammation predicts response to immune checkpoint blockade in human melanoma. Current theories on regulation of inflammation center on anti-tumor T cell responses. Here we show that tumor associated B cells are vital to melanoma associated inflammation. Human B cells express pro- and anti-inflammatory factors and differentiate into plasmablast-like cells when exposed to autologous melanoma secretomes in vitro. This plasmablast-like phenotype can be reconciled in human melanomas where plasmablast-like cells also express T cell-recruiting chemokines CCL3, CCL4, CCL5. Depletion of B cells in melanoma patients by anti-CD20 immunotherapy decreases tumor associated inflammation and CD8+ T cell numbers. Plasmablast-like cells also increase PD-1+ T cell activation through anti-PD-1 blockade in vitro and their frequency in pretherapy melanomas predicts response and survival to immune checkpoint blockade. Tumor associated B cells therefore orchestrate and sustain melanoma inflammation and may represent a predictor for survival and response to immune checkpoint blockade therapy.

SOX2 as a target for immunotherapy of pediatric gliomas.

2017 ◽  
Vol 35 (15_suppl) ◽  
pp. e22012-e22012 ◽  
Author(s):  
Juan Vasquez ◽  
Anita Huttner ◽  
Lin Zhang ◽  
Asher Marks ◽  
Amy Chan ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
Tumor Immunity ◽  
Immune Checkpoint ◽  
Cell Mass ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
Low Grade ◽  
Glial Tumors

e22012 Background: New treatments are needed to improve outcomes for pediatric gliomas. Immune checkpoint inhibitors are effective therapies in tumors with a high mutation burden that express multiple neo-antigens. However, for pediatric tumors that carry few mutations, there is a need to identify new antigenic targets of anti-tumor immunity. SOX2 is an embryonal stem cell antigen implicated in the biology of glioma initiating cells. Expression of SOX2 by pediatric glial tumors, and the capacity of the immune system in these patients to recognize SOX2, has not been studied. Methods: We examined the expression of SOX2 on paraffin-embedded tissue from pediatric glial tumors (n = 30). The presence of T cell immunity to SOX2 was examined in both blood and tumor-infiltrating T cells using antigen-dependent cytokine and T cell proliferation assays (n = 15). The nature of tumor-infiltrating immune cells in glial tumors (n = 4) was analyzed using single cell mass cytometry. Results: SOX2 is expressed by tumor cells but not surrounding normal tissue in all low grade gliomas (n = 15), high grade gliomas (n = 7), ependymomas (n = 3) and in 60% of oligodendrogliomas (n = 5). T cells against SOX2 can be detected in blood and tumor tissue in 33% of patients. CD4 and CD8 tumor infiltrating T-cells display a higher proportion of PD-1 expression compared to circulating T cells (p < 0.05). Glial CD4 and CD8 T cells are enriched for tissue resident memory phenotype (TRM; CD45RO+, CD69+, CCR7-) and the expression of PD-1 is primarily on these TRM cells (p < 0.05). A subset of CD4 and CD8 TRM cells also co-express multiple inhibitory checkpoints including PD-L1 and TIGIT. Glial tumors also contain NK cells with reduced expression of lytic granzyme (p < 0.05). Conclusions: Our data demonstrate in vivo immunogenicity of SOX2, which is specifically overexpressed on pediatric glial tumor cells. Our data also suggest that the TRM subset of tumor-infiltrating T cells may be key targets for immune checkpoint blockade, and harnessing tumor immunity will likely require the combined targeting of multiple inhibitory checkpoints. Future efforts to target SOX2 with dendritic cell vaccines combined with immune checkpoint blockade could provide effective tumor immunity and improve outcomes in pediatric brain tumors.

scholarly journals HDAC6 Inhibition Alleviates CLL-Induced T-Cell Dysfunction and Enhances Immune Checkpoint Blockade Efficacy in the Eμ-TCL1 Model

2020 ◽  
Vol 11 ◽  
Author(s):  
Kamira Maharaj ◽  
John J. Powers ◽  
Melanie Mediavilla-Varela ◽  
Alex Achille ◽  
Wael Gamal ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Immune Checkpoint ◽  
Immune Checkpoint Blockade ◽  
Tumor Burden ◽  
Checkpoint Blockade ◽  
Cell Phenotype ◽  
Cell Dysfunction ◽  
T Cell Dysfunction

Development of chronic lymphocytic leukemia (CLL) is associated with severe immune dysfunction. T-cell exhaustion, immune checkpoint upregulation, and increase of regulatory T cells contribute to an immunosuppressive tumor microenvironment. As a result, CLL patients are severely susceptible to infectious complications that increase morbidity and mortality. CLL B-cell survival is highly dependent upon interaction with the supportive tumor microenvironment. It has been postulated that the reversal of T-cell dysfunction in CLL may be beneficial to reduce tumor burden. Previous studies have also highlighted roles for histone deacetylase 6 (HDAC6) in regulation of immune cell phenotype and function. Here, we report for the first time that HDAC6 inhibition exerts beneficial immunomodulatory effects on CLL B cells and alleviates CLL-induced immunosuppression of CLL T cells. In the Eμ-TCL1 adoptive transfer murine model, genetic silencing or inhibition of HDAC6 reduced surface expression of programmed death-ligand 1 (PD-L1) on CLL B cells and lowered interleukin-10 (IL-10) levels. This occurred concurrently with a bolstered T-cell phenotype, demonstrated by alteration of coinhibitory molecules and activation status. Analysis of mice with similar tumor burden indicated that the majority of T-cell changes elicited by silencing or inhibition of HDAC6 in vivo are likely secondary to decrease of tumor burden and immunomodulation of CLL B cells. The data reported here suggest that CLL B cell phenotype may be altered by HDAC6-mediated hyperacetylation of the chaperone heat shock protein 90 (HSP90) and subsequent inhibition of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. Based on the beneficial immunomodulatory activity of HDAC6 inhibition, we rationalized that HDAC6 inhibitors could enhance immune checkpoint blockade in CLL. Conclusively, combination treatment with ACY738 augmented the antitumor efficacy of anti-PD-1 and anti-PD-L1 monoclonal antibodies in the Eμ-TCL1 adoptive transfer murine model. These combinatorial antitumor effects coincided with an increased cytotoxic CD8+ T-cell phenotype. Taken together, these data highlight a role for HDAC inhibitors in combination with immunotherapy and provides the rationale to investigate HDAC6 inhibition together with immune checkpoint blockade for treatment of CLL patients.

ALL Progression Induces PD1 on T Cells and Blockade of PD1 Enhances Adoptive Immunotherapy

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2587-2587 ◽  
Author(s):  
Chad R Burk ◽  
William Fix ◽  
Haiying Qin ◽  
Terry J Fry
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Poor Response ◽  
Cell Phenotype ◽  
Early Progression ◽  
Pd1 Blockade

Abstract Abstract 2587 Background: Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy and, despite tremendous success in therapy over the past 3 decades, remains a primary cause of cancer-related mortality in children. Enthusiasm for the use cellular immunotherapy for ALL has been tempered by the poor response to donor lymphocyte infusions following allogeneic hematopoietic stem cell transplantation. However, ALL blasts are susceptible to T cell and NK cell mediated lysis in vitro suggesting that poor response to in vivo immune interventions may be due to events occurring during the priming of the immune response. Using a murine model of precursor B cell ALL we examined the impact of leukemia progression on T cells in vivo. Methods: We developed a transplantable syngeneic model of pediatric ALL derived from transgeneic mice expressing human E2aPBX1, a recurring translocation present in 5% of pediatric leukemia (Bijl et al, Genes and Development, 2005). This murine line displays a precursor B cell phenotype and results in 100% lethality following injection of 100,000 cells (Qin et al, ASH, 2010). Using congenic (CD45.1) B6 recipients, we tracked the early progression of ALL in vivo and examined the T cells in the leukemia-containing compartments by flow cytometry and PCR. Results: Using congenic markers, ALL cells can be detected in bone marrow as early as 3 days following intravenous injection of 1,000,000 cells with a sensitivity of 0.01%. Spleen and lymph node involvement was seen later (10 days) followed by the detection of circulating blasts by 2 weeks. E2aPBX1 cells express variable levels of costimulatory molecules in vitro with no change in expression during in vivo progression. Notably, PDL1 and PDL2 are expressed both in vitro and in vivo at higher levels than on non-malignant precursor B cells in leukemia-bearing mice. Remarkably, although PD1+ T cells are not seen in the bone marrow of non-leukemia-bearing mice, PD1 expression on bone marrow T cells was markedly increased during progression such that 60–80% of all bone marrow CD4 and CD8 T cells were positive by 2 weeks following leukemia injection (figure). In addition to expression of PD1, these T cells also co-expressed Tim3, a phenotype associated with T cell exhaustion. Blockade of PD1 or PDL1 starting 3 days following leukemia injection had no impact on leukemia progression. However, combining PD1 blockade with the adoptive transfer of T cells from leukemia-primed donors resulted in improved survival compared to primed T cells alone (p=0.0004). Conclusions: Early progression of ALL results in the induction of PD1 and Tim3 on T cells in vivo. Combination of PD1 blockade plus adoptive T cell therapy results in therapeutic benefit suggesting that this axis may be an attractive target in ALL. Disclosures: No relevant conflicts of interest to declare.

scholarly journals 714 PD1 x TGFβR2 bispecifics selectively block TGFβR2 on PD1-positive T cells, promote T cell activation, and elicit an anti-tumor response in solid tumors

2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A756-A756
Author(s):  
Gregory Moore ◽  
Suzanne Schubbert ◽  
Christine Bonzon ◽  
Kendra Avery ◽  
Rumana Rashid ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Solid Tumors ◽  
T Cell Activation ◽  
Tumor Response ◽  
Nsg Mice ◽  
Pd1 Blockade ◽  
Anti Tumor Activity

BackgroundTGFβ production by solid tumors and their microenvironment is a major mechanism used by tumors to avoid immunosurveillance. Blockade of TGFβ has been shown to promote an anti-tumor response; however, systemic blockade of TGFβ has also been associated with toxicity. We hypothesized that a PD1 x TGFβR2 bispecific antibody could selectively block the suppressive activity of TGFβ on tumor T cells and enhance their anti-tumor activity while avoiding the toxicity associated with systemic blockade.MethodsWe engineered bispecific antibodies that simultaneously engage PD1 and TGFβR2 using Xencor’s XmAb platform. The anti-TGFβR2 arm was tuned for optimal activity by introducing affinity-modulating amino acid substitutions. The activity of PD1 x TGFβR2 bispecifics was evaluated in vitro using a signaling assay to measure phosphorylated SMAD (pSMAD) by flow cytometry with exogenous TGFβ in unactivated and activated PBMC. In vivo activity was evaluated by monitoring the engraftment of human PBMC in NSG mice (huPBMC-NSG). Anti-tumor activity was assessed in huPBMC-NSG mice engrafted with established human cancer cell lines. Antibodies against other T cell targets were also incorporated into TGFβR2 bispecifics, and similarly evaluated in vitro and in vivo.ResultsPD1 x TGFβR2 bispecifics were confirmed to bind PD1 and block binding of TGFβ to TGFβR2. In vitro, we found that T cells from activated, serum-deprived PBMC exhibited robust induction of pSMAD in response to TGFβ, and PD1 x TGFβR2 bispecifics selectively inhibited pSMAD induction in PD1-positive T cells as demonstrated by over a 100-fold potency increase compared to an untargeted anti-TGFβR2 control. Additionally, we saw an enhancement of potency when evaluating blocking activity in activated (PD1-high) vs. unactivated (PD1-low) T cells. Similar selectivity was measured when comparing inhibition of pSMAD induction for activated T cells versus other PD1-negative, TGFβ-responsive immune cells. Intriguingly, TGFβR2 bispecifics incorporating antibodies against other T cell targets allowed for the targeting of a broader population of T cells while still conferring potent selectivity against target-negative cells. In vivo, treatment of huPBMC-NSG mice with TGFβR2 bispecifics promoted superior T cell engraftment and combined additively with PD1 blockade. Furthermore, TGFβR2 bispecific treatment of huPBMC-NSG mice containing established MDA-MB-231 triple-negative breast cancer tumors promoted an anti-tumor response that was also augmented with PD1 blockade.ConclusionsMultiple PD1 x TGFβR2 bispecifics were engineered to selectively block TGFβR2 on PD1-positive T cells and evaluated in vitro and in vivo. Compelling activity, including additivity with PD1 blockade, suggests that clinical development is warranted for the treatment of human malignancies.

scholarly journals Combined PD-L1 and TIM-3 blockade improves the expansion of fit human CD8+ antigen-specific T cells for adoptive immunotherapy

2021 ◽  
Author(s):  
Shirin Lak ◽  
Valérie Janelle ◽  
Anissa Djedid ◽  
Gabrielle Boudreau ◽  
Ann Brasey ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Checkpoint ◽  
Cell Expansion ◽  
Ex Vivo ◽  
Immune Checkpoint Blockade ◽  
Checkpoint Blockade ◽  
Immune Checkpoints ◽  
T Cell Expansion ◽  
And Function

AbstractBackgroundThe stimulation and expansion of antigen-specific T cells ex vivo enables the targeting of a multitude of cancer antigens. However, clinical scale T-cell expansion from rare precursors requires repeated stimulations ex vivo leading to T-cell terminal effector differentiation and exhaustion that adversely impact therapeutic potential. We leveraged immune checkpoint blockade relevant to antigen-specific CD8+ human T cells to improve the expansion and function of T cells targeting clinically relevant antigens.MethodsA clinically-compliant protocol relying on peptide-pulsed monocyte-derived dendritic cells and cytokines was used to expand antigen-specific CD8+ targeting the oncogenic Epstein-Barr virus (EBV) and the tumor associated antigen (TAA) Wilms Tumor 1 (WT1) protein. The effects of antibody-mediated blockade of immune checkpoints applied to the cultures (T-cell expansion, phenotypes and function) were assessed at various time points. Genomic studies including single cell RNA (scRNA) sequencing and T-cell receptor sequencing were performed on EBV-specific T cells to inform about the impact of immune checkpoint blockade on the clonal distribution and gene expression of the expanded T cells.ResultsSeveral immune checkpoints were expressed early by ex vivo expanded antigen-specific CD8+ T cells, including PD-1 and TIM-3 with co-expression matching evidence of T-cell dysfunction as the cultures progressed. The introduction of anti-PD-L1 (expressed by the dendritic cells) and anti-TIM-3 antibodies in combination (but not individually) to the culture led to markedly improved antigen-specific T-cell expansion based on cell counts, fluorescent multimer staining and functional tests. This was not associated with evidence of T-cell dysfunction when compared to T cells expanded without immune checkpoint blockade. Genomics studies largely confirmed these results, showing that double blockade does not impart specific transcriptional programs or patterns on TCR repertoires. However, our data indicate that combined blockade may nonetheless alter gene expression in a minority of clonotypes and have donor-specific impacts.ConclusionsThe manufacturing of antigen-specific CD8+ T cells can be improved in terms of yield and functionality using blockade of TIM-3 and the PD-L1/PD-1 axis in combination. Overcoming the deleterious effects of multiple antigenic stimulations through PD-L1/TIM-3 blockade is a readily applicable approach for several adoptive-immunotherapy strategies.

scholarly journals Interleukin-10 suppression enhances T-cell antitumor immunity and responses to checkpoint blockade in chronic lymphocytic leukemia

2020 ◽  
Author(s):  
J.R. Rivas ◽  
S.S. Alhakeem ◽  
Y. Liu ◽  
J.M. Eckenrode ◽  
F. Marti ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Chronic Lymphocytic Leukemia ◽  
Cell Function ◽  
Cell Activity ◽  
Interleukin 10 ◽  
Interferon Γ ◽  
Immune Checkpoint Blockade ◽  
Lymphocytic Leukemia ◽  
Checkpoint Blockade

AbstractT-cell dysfunction is a hallmark of B-cell Chronic Lymphocytic Leukemia (CLL). CLL cells downregulate T-cell responses by expressing regulatory molecules including programmed death ligand-1 (PD-L1) and Interleukin-10 (IL-10). Immune checkpoint blockade (ICB) aims to restore T-cell function by preventing the ligation of inhibitory receptors like PD-1, however most CLL patients do not respond well to this therapy. Thus, we investigated whether IL-10 suppression could enhance antitumor T-cell activity and improve responses to ICB. Since CLL IL-10 expression depends on Sp1, we utilized a novel, better tolerated mithramycin analogue, MTMox32E, to suppress CLL IL-10. We found MTMox32E inhibited mouse and human CLL IL-10 production and maintained T-cell effector function. In the Eμ-Tcl1 mouse model, treatment reduced plasma IL-10 and CLL burden while it increased CD8+ T-cell proliferation, effector and memory cell prevalence, and interferon-γ production. When combined with ICB, suppression of IL-10 improved responses to anti-PD-L1 as shown by a 4.5-fold decrease in CLL cell burden compared with anti-PD-L1 alone. Combination therapy also produced more interferon-γ+, cytotoxic effector KLRG1+, and memory CD8+ T-cells, with fewer exhausted T-cells than ICB alone. Since current therapies for CLL do not target IL-10, this provides a novel strategy to increase the efficacy of T-cell-based immunotherapies.

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