scholarly journals Deregulated Expression of Immune Checkpoints on Circulating CD4 T Cells May Complicate Clinical Outcome and Response to Treatment with Checkpoint Inhibitors in Multiple Myeloma Patients

2021 ◽  
Vol 22 (17) ◽  
pp. 9298
Author(s):  
Anna Kulikowska de Nałęcz ◽  
Lidia Ciszak ◽  
Lidia Usnarska-Zubkiewicz ◽  
Irena Frydecka ◽  
Edyta Pawlak ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Checkpoint Inhibitors ◽  
Effector Function ◽  
Response To Treatment ◽  
Immune Checkpoints ◽  
Effective Control ◽  
Small Subset

Unlike solid-tumor patients, a disappointingly small subset of multiple myeloma (MM) patients treated with checkpoint inhibitors derive clinical benefits, suggesting differential participation of inhibitory receptors involved in the development of T-cell-mediated immunosuppression. In fact, T cells in MM patients have recently been shown to display features of immunosenescence and exhaustion involved in immune response inhibition. Therefore, we aimed to identify the dominant inhibitory pathway in MM patients to achieve its effective control by therapeutic interventions. By flow cytometry, we examined peripheral blood (PB) CD4 T cell characteristics assigned to senescence or exhaustion, considering PD-1, CTLA-4, and BTLA checkpoint expression, as well as secretory effector function, i.e., capacity for IFN-γ and IL-17 secretion. Analyses were performed in a total of 40 active myeloma patients (newly diagnosed and treated) and 20 healthy controls. At the single-cell level, we found a loss of studied checkpoints’ expression on MM CD4 T cells (both effector (Teff) and regulatory (Treg) cells) primarily at diagnosis; the checkpoint deficit in MM relapse was not significant. Nonetheless, PD-1 was the only checkpoint distributed on an increased proportion of T cells in all MM patients irrespective of disease phase, and its expression on CD4 Teff cells correlated with adverse clinical courses. Among patients, the relative defect in secretory effector function of CD4 T cells was more pronounced at myeloma relapse (as seen in declined Th1/Treg and Th17/Treg cell rates). Although the contribution of PD-1 to MM clinical outcomes is suggestive, our study clearly indicated that the inappropriate expression of immune checkpoints (associated with dysfunctionality of CD4 T cells and disease clinical phase) might be responsible for the sub-optimal clinical response to therapeutic checkpoint inhibitors in MM.

scholarly journals Expansion of circulating peripheral TIGIT+CD226+ CD4 T cells with enhanced effector functions in dermatomyositis

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Wenli Li ◽  
Chuiwen Deng ◽  
Hanbo Yang ◽  
Xin Lu ◽  
Shanshan Li ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Checkpoint Inhibitors ◽  
Expression Profiles ◽  
Intracellular Cytokine Staining ◽  
Critical Role ◽  
Cell Subset ◽  
Effector Function ◽  
Response To Treatment

Abstract Background T cell Ig and ITIM domain (TIGIT)/CD226 pathway has a critical role in regulating T cell responses and has come to the forefront in cancer as a promising immunotherapeutic target. However, its role in autoimmune diseases is just beginning to be elucidated. Dermatomyositis (DM) is an autoimmune disease, in which T cell dysregulation plays a pivotal role, and importantly, it is a common immune-related adverse event in response to treatment of cancers with immune checkpoint inhibitors, but no studies have implicated the TIGIT/CD226 axis in DM. Methods We recruited 30 treatment-naïve DM patients and 26 healthy controls. Flow cytometry analysis was used to investigate the co-expression of TIGIT and CD226 on T cells in blood samples. Magnetic bead or FACS-based cell isolation, T cell proliferation assay, and intracellular cytokine staining were performed to analyze the functions of different TIGIT/CD226 phenotypes. Recombinant proteins CD155, CD112, and anti-CD226 antibodies were used to suppress the function of TIGIT/CD226-expressing CD4 T cells. Results Four distinct subsets of T cells based on TIGIT/CD226 co-expression, TIGIT+CD226−, TIGIT+CD226+, TIGIT−CD226+, and TIGIT−CD226−, were identified and characterized in DM patients. Our data showed that the function of CD4 T cell subset varied by the TIGIT/CD226 phenotype. An elevated TIGIT+CD226+ CD4 subset with enhanced effector function was observed in patients with DM, especially the patients complicated with interstitial lung disease. This subpopulation was closely related to DM activity and decreased significantly in DM remission after treatment. Furthermore, the effector function of TIGIT+CD226+ CD4 subset could be suppressed by blocking CD226. Conclusion Our data revealed that the TIGIT and CD226 expression profiles could be used to identify functionally distinct subsets of CD4 T cells and TIGIT+CD226+ CD4 T cells is a significant subset in DM with enhanced frequency and effector function. This abnormal subset could be suppressed by blocking CD226, providing insight into the therapeutic target of the TIGIT/CD226 axis.

scholarly journals CD4+ T-cell killing of multiple myeloma cells is mediated by resident bone marrow macrophages

2020 ◽  
Vol 4 (12) ◽  
pp. 2595-2605 ◽  
Author(s):  
Ole Audun W. Haabeth ◽  
Kjartan Hennig ◽  
Marte Fauskanger ◽  
Geir Åge Løset ◽  
Bjarne Bogen ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Antigen Presenting Cells ◽  
Bone Marrow Microenvironment ◽  
Cd4 T Cell ◽  
Myeloma Cells ◽  
Antigen Presenting

Abstract CD4+ T cells may induce potent antitumor immune responses through interaction with antigen-presenting cells within the tumor microenvironment. Using a murine model of multiple myeloma, we demonstrated that adoptive transfer of idiotype-specific CD4+ T cells may elicit curative responses against established multifocal myeloma in bone marrow. This finding indicates that the myeloma bone marrow niche contains antigen-presenting cells that may be rendered tumoricidal. Given the complexity of the bone marrow microenvironment, the mechanistic basis of such immunotherapeutic responses is not known. Through a functional characterization of antitumor CD4+ T-cell responses within the bone marrow microenvironment, we found that killing of myeloma cells is orchestrated by a population of bone marrow–resident CD11b+F4/80+MHC-IIHigh macrophages that have taken up and present secreted myeloma protein. The present results demonstrate the potential of resident macrophages as powerful mediators of tumor killing within the bone marrow and provide a basis for novel therapeutic strategies against multiple myeloma and other malignancies that affect the bone marrow.

scholarly journals Disparate Primary and Secondary Allospecific CD8+ T Cell Cytolytic Effector Function in the Presence or Absence of Host CD4+ T Cells

2007 ◽  
Vol 179 (1) ◽  
pp. 80-88 ◽  
Author(s):  
Phillip H. Horne ◽  
Mitchel A. Koester ◽  
Kartika Jayashankar ◽  
Keri E. Lunsford ◽  
Heather L. Dziema ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Cd8 T Cell ◽  
Effector Function

Decrease in CD4+ T Cells in Multiple Myeloma Patients Receiving Bortezomib.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 3865-3865
Author(s):  
Ulrike Heider ◽  
Jessica Rademacher ◽  
Martin Kaiser ◽  
Ivana von Metzler ◽  
Karin Marquardt ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
T Cells ◽  
Herpes Zoster ◽  
T Cell ◽  
Peripheral Blood ◽  
Cd4 T Cells ◽  
Proteasome Inhibitor ◽  
Median Number ◽  
Cell Subpopulation ◽  
Cd4 Lymphocytes

Abstract Abstract 3865 Poster Board III-801 The proteasome inhibitor bortezomib is highly effective in multiple myeloma and widely used in this disease. Recently, an increased incidence of opportunistic infections, particularly varicella zoster virus (VZV) reactivation (herpes zoster), was reported in myeloma patients undergoing treatment with bortezomib. We therefore analyzed the influence of bortezomib on lymphocyte subsets, particularly T-cell subpopulations, in the peripheral blood of myeloma patients before initiation and during the treatment. In addition, the results were correlated with the incidence of VZV reactivation. Peripheral blood samples from 53 multiple myeloma patients treated with bortezomib were collected. Eight of the patients were previously untreated and received bortezomib as front-line therapy, whereas 45 patients were treated in the relapse setting. Different subsets of lymphocytes in the peripheral blood were analyzed by four-color flow cytometry. A decrease of CD4+ T-cells was seen in 42/53 patients (77%). The median numbers of CD4+ T-cells decreased by 45% from 494/μl (range 130-2187) to 274/μl (range 41-1404) during therapy with the proteasome inhibitor (p < 0.001). In the majority of the patients (76%), CD4+ lymphocytes dropped to < 400/μl during bortezomib treatment, and in 18/53 patients (33.9%) the CD4+ T cells fell below 200/μl. The minimum CD4+ cell count was seen at a medium of 6 weeks (range 2-22) after the initiation of treatment, but recovered within a few weeks. The median number of circulating CD3+/CD8+ T-cells decreased by 33.6% from 420/μl (range 48-1518) to 279/μl (range 19-1693) during bortezomib therapy (p < 0.001). This was accompanied by a slight decrease of the median CD4/CD8 ratio from 1.17 (range 0.23-6.0) to 1.0 (range 0.15-4.18). Importantly, all of the patients receiving bortezomib as first-line treatment had a normal CD4+ lymphocyte count before initiation of treatment, and all of them showed a decrease of CD3+/ CD4+ cells during the therapy. The median number of circulating CD4+ T-cells in this subgroup decreased by 70% from 924/μl (range 479-1579) to 276/μl (range 80-626) (p < 0.01). The incidence of herpes zoster reactivation was 5.3% in the whole population of myeloma patients receiving bortezomib. 19/53 patients received acyclovir at a dose of 400mg daily as prophylaxis against VZV reactivation. In this group, none of the patients developed herpes zoster. The incidence of VZV reactivation in patients not receiving acyclovir was 3/34 (8.8%). Importantly, occurrence of herpes zoster was associated with reduced CD4+ T cell subpopulation: all patients who developed herpes zoster had CD4+ lymphocytes < 400/μl. In conclusion, our results show that bortezomib leads to a transient decrease in CD4+ lymphocytes, accompanied by an increased incidence of VZV infections. The antiviral prophylaxis with acyclovir is effective in myeloma patients treated with bortezomib. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Immune checkpoint expression on HIV-specific CD4+ T cells and response to their blockade are dependent on lineage and function

2021 ◽  
Author(s):  
Elsa Brunet-Ratnasingham ◽  
Antigoni Morou ◽  
Mathieu Dube ◽  
Julia Niessl ◽  
Amy E. Baxter ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Immune Checkpoints ◽  
Chronic Infections ◽  
Cell Functions ◽  
Art Initiation ◽  
Specific Regulation ◽  
And Function

Background: Antigen-specific T cell impairment is observed in chronic infections. CD4+ T cells are diverse in phenotype and function; how their different lineages are impacted by inhibitory immune checkpoints (IC) is unknown. Methods: We examined IC expression and function in HIV-specific CD4+ T cells of viremic individuals prior to ART initiation and persons with spontaneous or therapy-induced viral suppression. We investigated IC patterns associated with exhaustion-related transcription factors and chemokine receptors using cytokine-independent activation-induced marker assays. We determined effector functions representative of TFH, TH1 and TH17/TH22 using ultra-sensitive RNA flow cytometric fluorescence in situ hybridization (FISH), and their response to IC blockade. Findings: The dysfunction-related transcription factor TOX was elevated in HIV-specific CD4+ T cells of viremic patients, and its expression was associated with lineage differentiation. We observed a hierarchy of PD-1, TIGIT and CD200 expression associated with both infection status and effector profile. In vitro responsiveness to PD-L1 blockade varied with defined CD4+ T cell functions rather than IC expression levels: frequencies of cells with TH1- and TH17/TH22-, but not TFH-related functions, increased. Response to PD-L1 blockade was strongest in viremic participants and reduced after ART initiation. Interpretation: Our data highlight a polarization-specific regulation of IC expression and differing sensitivities of antigen-specific Thelper subsets to PD-1-mediated inhibition. This heterogeneity may direct ICB efficacy on CD4+ T cells in HIV infection.

scholarly journals Breast Cancer Cells and PD-1/PD-L1 Blockade Upregulate the Expression of PD-1, CTLA-4, TIM-3 and LAG-3 Immune Checkpoints in CD4+ T Cells

Vaccines ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 149 ◽  
Author(s):  
Saleh ◽  
Toor ◽  
Khalaf ◽  
Elkord
Keyword(s):  
Breast Cancer ◽  
T Cells ◽  
T Cell ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Checkpoint Inhibitors ◽  
T Cell Subsets ◽  
Cd4 T Cell ◽  
Immune Checkpoints ◽  
Tnbc Cell

: Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype, and it exhibits resistance to common breast cancer therapies. Immune checkpoint inhibitors (ICIs) targeting programmed cell death 1 (PD-1) and its ligand, PD-L1, have been approved to treat various cancers. However, the therapeutic efficacy of targeting PD-1/PD-L1 axis in breast cancer is under clinical investigation. In addition, the mechanisms of action of drugs targeting PD-1 and PD-L1 have not been fully elucidated. In this study, we investigated the effect of human TNBC cell lines, MDA-MB-231 and MDA-MB-468, and the non-TNBC cell line, MCF-7, on the expression of immune checkpoints (ICs) on CD4+ T cell subsets, including regulatory T cells (Tregs), using a co-culture system. We also examined the effect of blocking PD-1 or PD-L1 separately and in combination on IC expression by CD4+ T cell subsets. We found that breast cancer cells upregulate the expression of ICs including PD-1, cytotoxic T lymphocyte-associated antigen-4 (CTLA-4), T cell immunoglobulin and mucin domain-containing protein 3 (TIM-3) and lymphocyte activation gene-3 (LAG-3) in CD4+ T cell subsets. We also found that the co-blockade of PD-1 and PD-L1 further upregulates the co-expression of TIM-3 and LAG-3 on CD4+CD25+ T cells and CD4+CD25+FoxP3+Helios+ Tregs in the presence of TNBC cells, but not in non-TNBC cells. Our results indicate the emergence of compensatory inhibitory mechanisms, most likely mediated by Tregs and activated non-Tregs, which could lead to the development of TNBC resistance against PD-1/PD-L1 blockade.

IMMU-52. EFFECTS OF IMMUNE CHECKPOINT BLOCKADE ON ANTIGEN-SPECIFIC CD8+ T CELLS FOR USE IN ADOPTIVE CELLULAR THERAPY

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi104-vi104
Author(s):  
Elizabeth Ogando-Rivas ◽  
Paul Castillo ◽  
Noah Jones ◽  
Vrunda Trivedi ◽  
Jeffrey Drake ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cellular Therapy ◽  
Checkpoint Inhibitors ◽  
Cell Subset ◽  
Checkpoint Blockade ◽  
Immune Checkpoints ◽  
Effector Memory ◽  
Dependent Manner

Abstract BACKGROUND Adoptive T-cell therapies have been successfully used as treatment for patients diagnosed with advanced cancers. Unfortunately, for some refractory cancers, they have failed. To overcome this, checkpoint inhibitors have shown to rescue immune anti-tumor responses. We hypothesized that in-vitro checkpoint blockade during T-cell stimulation and expansion with RNA-pulsed dendritic cells may enhance the activity of antigen-specific T-cells and improve the efficacy of ACT platforms. METHODS Human PBMCs were isolated from CMV seropositive donors to generate DCs and pulsed them with CMVpp65-mRNA to educate T-cells in co-culture for 15-days. We targeted pp65 antigen which is ubiquitously expressed by glioblastoma cells. Three checkpoint blockade conditions were evaluated (anti-PD1, anti-Tim3 and anti-PD1+Tim3). IL2 was added every 3 days as well as the blockade antibodies. Immunephenotyping was performed on Day-0 and Day-15. Polyfunctional antigen specific responses were evaluated upon rechallenge with CMVpp65 peptides. RESULTS CMVpp65 activated CD8+ T-cells upregulate Lag3 and Tim3 (p= &lt; 0.0001). Tim3 blockade alone or in combination led to a significant upregulation of Lag3 expression on CD8+pp65Tetramer+ central memory, effector memory, and TEMRA T-cells. This latter T-cell subset uniquely maintain double-positive Tim3/Lag3 expression after blockade. In contrast, PD-1 blockade had minimal effects on Tim3 or Lag3 expression. In addition, IFN-g secretion was reduced in T-cells treated with Tim3 blockade in a dose-dependent manner (p= 0.004). CONCLUSION In this study, we have identified a potential activating component of Tim3 and linkage between Tim3 and Lag3 signaling upon blocking Tim3 axis during T-cell antigen presenting cell interactions that should be considered when targeting immune checkpoints for clinical use.

Tigit, CD226 and PD-L1/PD-1 Are Highly Expressed By Marrow-Infiltrating T Cells in Patients with Multiple Myeloma

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 2102-2102 ◽  
Author(s):  
Mahesh Yadav ◽  
Cherie Green ◽  
Connie Ma ◽  
Alberto Robert ◽  
Andrew Glibicky ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Bone Marrow ◽  
Flow Cytometry ◽  
T Cells ◽  
T Cell ◽  
Nk Cells ◽  
Cd8 T Cells ◽  
Cd4 T Cells ◽  
Plasma Cells ◽  
Color Flow

Abstract Introduction:TIGIT (T-cell immunoglobulin and immunoreceptor tyrosine-based inhibitory motif [ITIM] domain) is an inhibitory immunoreceptor expressed by T and natural killer (NK) cells that is an important regulator of anti-tumor and anti-viral immunity. TIGIT shares its high-affinity ligand PVR (CD155) with the activating receptor CD226 (DNAM-1). We have recently shown that TIGIT blockade, together with PD-L1/PD-1 blockade, provides robust efficacy in syngeneic tumor and chronic viral infection models. Importantly, CD226 blockade abrogates the benefit of TIGIT blockade, suggesting additional benefit of TIGIT blockade through elaboration of CD226-mediated anti-tumor immunity, analogous to CTLA-4/CD28 regulation of T-cell immunity. Whether TIGIT and CD226 are expressed in patients with multiple myeloma (MM) and how TIGIT expression relates to PD-L1/PD-1 expression is unknown. Here we evaluate expression of TIGIT, CD226, PD-1 and PD-L1 in patients with MM to inform novel immunotherapy combinations. Methods:We performed multi-color flow cytometry (n = 25 patients), and multiplex qRT-PCR (n = 7) on bone marrow specimens from patients with MM to assess expression of TIGIT, CD226, PD-1, and PD-L1 on tumor and immune cells. Cells were stained with fluorescently conjugated monoclonal antibodies to label T cells (CD3, CD4, CD8), NK cells (CD56, CD3), plasma cells (CD38, CD45, CD319, CD56), inhibitory/activating receptors (PD-1, TIGIT, PD-L1, CD226), and an amine-reactive viability dye (7-AAD). Stained and fixed cells were analyzed by flow cytometry using BD FACSCanto™ and BD LSRFortessa™. Results:TIGIT, CD226 and PD-L1/PD-1 were detectable by flow cytometry in all patients with MM who were tested, with some overlapping and distinct expression patterns. TIGIT was commonly expressed by marrow-infiltrating CD8+ T cells (median, 65% of cells), CD4+ T cells (median, 12%) and NK cells. In contrast, CD226 was more commonly expressed by marrow-infiltrating CD4+ T cells (median, 74%) compared with CD8+ T cells (median, 38%). PD-1 was expressed by marrow-infiltrating CD8+ T cells (median 38%) and CD4+ T cells (median, 16%). TIGIT was co-expressed with PD-1 on CD8+ T cells (67%-97% TIGIT+ among PD-1+), although many PD-1-negative CD8+ T cells also expressed TIGIT (39%-78% of PD-1-negative). PD-L1 was also expressed by CD8+ (median, 23%) and CD4+ (median, 8%) T cells in addition to MM plasma cells (median, 95%), albeit with significantly lower intensity on T cells compared with plasma cells. The expression of TIGIT and PD-L1 mRNA was highly correlated (R2 = 0.80). Analysis of PVR expression will also be presented. Conclusions: TIGIT, CD226, PD-1, and PD-L1 were commonly expressed in MM bone marrow, but with different patterns. Among CD8+ T cells, the frequency of TIGIT+ T cells was almost twice that of PD-1+ T cells, whereas the majority of CD4+ T cells expressed CD226. TIGIT blockade may complement anti-PD-L1/PD-1 immunotherapy by activating distinct T-cell/NK-cell subsets with synergistic clinical benefit. These results provide new insight into the immune microenvironment of MM and rationale for targeting both the PD-L1/PD-1 interaction and TIGIT in MM. Disclosures Yadav: Genentech, Inc.: Employment. Green:Genentech, Inc.: Employment. Ma:Genentech, Inc.: Employment. Robert:Genentech, Inc.: Employment. Glibicky:Makro Technologies Inc.: Employment; Genentech, Inc.: Consultancy. Nakamura:Genentech, Inc.: Employment. Sumiyoshi:Genentech, Inc.: Employment. Meng:Genentech, Inc.: Employment, Equity Ownership. Chu:Genentech Inc.: Employment. Wu:Genentech: Employment. Byon:Genentech, Inc.: Employment. Woodard:Genentech, Inc.: Employment. Adamkewicz:Genentech, Inc.: Employment. Grogan:Genentech, Inc.: Employment. Venstrom:Roche-Genentech: Employment.

Attenuation of Immune Suppression to Complement Glioma Immunotherapy

2021 ◽  
Author(s):  
◽  
Cameron Field
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Cell Function ◽  
Combined Treatment ◽  
Checkpoint Blockade ◽  
Immune Checkpoints ◽  
Inkt Cells ◽  
Effector Cells ◽  
The Brain

<p>Glioblastoma Multiforme (GBM) is a malignant primary brain tumour with an extremely poor prognosis. Following surgical resection, radiotherapy, and concomitant and adjuvant chemotherapy, median survival is only 12-15 months. New therapeutic approaches are therefore desperately needed.  Accumulating evidence suggests that activated T cells are capable of selectively targeting and eliminating tumour cells, even in the brain, making vaccine-mediated immunotherapy a promising candidate for the treatment of brain cancers. However, cancer vaccination has generally been disappointing in the clinic, and is unlikely to bestow long-term survival unless suppressive mechanisms are overcome. Checkpoint blockade is a recent treatment modality that enhances naturally occurring T cell responses to cancer by relieving suppression mediated by immune checkpoints – molecular signals that prevent T cell function. While significant clinical responses are often seen, it is clear that most patients fail to respond to checkpoint blockade alone. Therefore, there is considerable interest in combining the different immunotherapeutic strategies, with vaccines providing an immunogenic stimulus to induce anti-tumour T cells, and checkpoint blockade to ensure T cell function is retained.  An orthotopic murine model of glioma was utilised to examine this form of combined treatment. Immune responses induced with a unique whole-cell vaccine that utilises the adjuvant properties of invariant natural killer T cells (iNKT cells) were able to resist tumour challenge, but failed to eradicate established tumours. When the vaccine was combined with blocking antibodies to the immune checkpoint molecule cytotoxic T lymphocyte antigen-4 (α-CTLA-4) regression of established intracranial tumours was observed, whereas α-CTLA-4 was ineffective as a monotherapy. In contrast, combining the vaccine with antibodies to programmed death-1 (α-PD-1) or lymphocyte activation gene-3 (LAG-3) failed to provide any survival advantage. This was despite α-PD-1 being effective against the same tumour implanted subcutaneously, suggesting efficacy in the orthotopic setting was limited by poor access of α-PD-1 to effector T cells within the brain.  The effective combination of vaccine and α-CTLA-4 was associated with enhanced proliferation and accumulation of T cells in the lymphoid tissues without any obvious changes in the adjuvant function of iNKT cells or altered numbers of regulatory T cells, suggesting recently primed T cells were the targets of checkpoint inhibition. While tumours regressing under this combined treatment were highly infiltrated with a variety of leukocytes, tumour eradication was strictly dependent on CD4⁺ T cells.  Further interrogation of the cell-types responsible for anti-tumour activity revealed that CD11b⁺ cells were required for therapy, although it remains to be established whether these cells were involved in T cell priming or served as anti-tumour effectors in their own right, possibly under the influence of activated CD4⁺ T cells. In addition, therapy was hampered, although not entirely eliminated, in hosts deficient in interferon-γ. Therapy was also reduced significantly, but not entirely, in hosts deficient in perforin. In vitro studies showed that restimulated splenocytes from animals that had received the combined therapy were able to kill glioma cells in a perforin and MHC-II dependent manner, suggesting that cytotoxic CD4⁺ T cells were important effector cells.  Overall, these results demonstrate that immunotherapeutic vaccination can be combined effectively with checkpoint blockade to induce effective immune responses against glioma. The immune response induced in combination with CTLA-4 blockade differs from many other cancer models, with a strict dependence on CD4⁺ T cells that can serve either as cytotoxic effector cells, or potentially as modulators of other accessory cells. Furthermore, the tumour location presents new challenges, with access of inhibitors to the brain, particularly important if immune checkpoints on intratumoural effector cells are to be targeted. In this context, strategies to improve access of checkpoint inhibitors like α-PD-1 and α-LAG3 to the brain warrant further investigation.</p>

Attenuation of Immune Suppression to Complement Glioma Immunotherapy

2021 ◽  
Author(s):  
◽  
Cameron Field
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Cell Function ◽  
Combined Treatment ◽  
Checkpoint Blockade ◽  
Immune Checkpoints ◽  
Inkt Cells ◽  
Effector Cells ◽  
The Brain

<p>Glioblastoma Multiforme (GBM) is a malignant primary brain tumour with an extremely poor prognosis. Following surgical resection, radiotherapy, and concomitant and adjuvant chemotherapy, median survival is only 12-15 months. New therapeutic approaches are therefore desperately needed.  Accumulating evidence suggests that activated T cells are capable of selectively targeting and eliminating tumour cells, even in the brain, making vaccine-mediated immunotherapy a promising candidate for the treatment of brain cancers. However, cancer vaccination has generally been disappointing in the clinic, and is unlikely to bestow long-term survival unless suppressive mechanisms are overcome. Checkpoint blockade is a recent treatment modality that enhances naturally occurring T cell responses to cancer by relieving suppression mediated by immune checkpoints – molecular signals that prevent T cell function. While significant clinical responses are often seen, it is clear that most patients fail to respond to checkpoint blockade alone. Therefore, there is considerable interest in combining the different immunotherapeutic strategies, with vaccines providing an immunogenic stimulus to induce anti-tumour T cells, and checkpoint blockade to ensure T cell function is retained.  An orthotopic murine model of glioma was utilised to examine this form of combined treatment. Immune responses induced with a unique whole-cell vaccine that utilises the adjuvant properties of invariant natural killer T cells (iNKT cells) were able to resist tumour challenge, but failed to eradicate established tumours. When the vaccine was combined with blocking antibodies to the immune checkpoint molecule cytotoxic T lymphocyte antigen-4 (α-CTLA-4) regression of established intracranial tumours was observed, whereas α-CTLA-4 was ineffective as a monotherapy. In contrast, combining the vaccine with antibodies to programmed death-1 (α-PD-1) or lymphocyte activation gene-3 (LAG-3) failed to provide any survival advantage. This was despite α-PD-1 being effective against the same tumour implanted subcutaneously, suggesting efficacy in the orthotopic setting was limited by poor access of α-PD-1 to effector T cells within the brain.  The effective combination of vaccine and α-CTLA-4 was associated with enhanced proliferation and accumulation of T cells in the lymphoid tissues without any obvious changes in the adjuvant function of iNKT cells or altered numbers of regulatory T cells, suggesting recently primed T cells were the targets of checkpoint inhibition. While tumours regressing under this combined treatment were highly infiltrated with a variety of leukocytes, tumour eradication was strictly dependent on CD4⁺ T cells.  Further interrogation of the cell-types responsible for anti-tumour activity revealed that CD11b⁺ cells were required for therapy, although it remains to be established whether these cells were involved in T cell priming or served as anti-tumour effectors in their own right, possibly under the influence of activated CD4⁺ T cells. In addition, therapy was hampered, although not entirely eliminated, in hosts deficient in interferon-γ. Therapy was also reduced significantly, but not entirely, in hosts deficient in perforin. In vitro studies showed that restimulated splenocytes from animals that had received the combined therapy were able to kill glioma cells in a perforin and MHC-II dependent manner, suggesting that cytotoxic CD4⁺ T cells were important effector cells.  Overall, these results demonstrate that immunotherapeutic vaccination can be combined effectively with checkpoint blockade to induce effective immune responses against glioma. The immune response induced in combination with CTLA-4 blockade differs from many other cancer models, with a strict dependence on CD4⁺ T cells that can serve either as cytotoxic effector cells, or potentially as modulators of other accessory cells. Furthermore, the tumour location presents new challenges, with access of inhibitors to the brain, particularly important if immune checkpoints on intratumoural effector cells are to be targeted. In this context, strategies to improve access of checkpoint inhibitors like α-PD-1 and α-LAG3 to the brain warrant further investigation.</p>

Sign in / Sign up

Export Citation Format

Share Document