Vγ9Vδ2 T-cells are potent inhibitors of SARS-CoV-2 replication and represent effector phenotypes in COVID-19 patients.

Vγ9Vδ2 T-cells play a key role in the innate immune response to viral infections through butyrophilin (BTN)-3A. Here, we reported that blood Vγ9Vδ2 T-cells decreased in clinically mild COVID-19 compared to healthy volunteers (HV), and was maintained up to 28-days and in the recovery period. Terminally differentiated Vγ9Vδ2 T-cells tend to be enriched on the day of diagnosis, 28-days after and during the recovery period. These cells showed cytotoxic and inflammatory activities following anti-BTN3A activation. BTN3A upregulation and Vγ9Vδ2 T-cell infiltration were observed in a lung biopsy from a fatal SARS-CoV-2 infection. In vitro, SARS-CoV-2 infection increased BTN3A expression in macrophages and lung cells that enhanced the anti-SARS-CoV-2 Vγ9Vδ2 T-cells cytotoxicity and IFNγ and TNFα. Increasing concentrations of anti-BTN3A lead to viral replication inhibition. Altogether, we report that Vγ9Vδ2 T-cells are important in the immune response against SARS-CoV-2 infection and that activation by an anti-BTN3A antibody may enhance their response.

Endosomal trafficking inhibitor EGA can control TLR7-mediated IFNα expression by human plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDC) are the major producer of type 1 IFN in response to TLR7 agonists. Aberrant TLR7 activation and type 1 IFN expression by pDCs are linked to the pathogenesis of certain types of autoimmune diseases, including systemic lupus erythematosus (SLE). This study investigated the underlying mechanisms for TLR7-mediated cytokine expression by pDCs using a late endosome trafficking inhibitor, EGA (4-bromobenzaldehyde N-(2,6-dimethylphenyl) semicarbazone). We found that EGA treatment decreased IFNα expression by pDCs stimulated with imiquimod (R837), single-stranded RNA40, and influenza virus. EGA also decreased TNFα expression and secretion by R837-stimulated pDCs. Mechanistically, EGA treatment decreased phosphorylation of IKKα/ß, STAT1, and p38, and prolonged degradation of IκBα. Furthermore, EGA treatment decreased the colocalization of 3F, a substituted adenine TLR7 agonist, with LAMP1+ compartments in pDCs. EGA was also capable of diminishing IFNα expression by SLE pDCs treated with R837 or live PR8/A/34 influenza viruses. Therefore, we concluded that trafficking of TLR7 agonists to LAMP1+ compartments is important for IFNα expression by pDCs. Data from this study support additional examinations of the potential benefits of EGA in treating type 1 IFN-associated inflammatory diseases in the future.

Dysthyroidism during immune checkpoint inhibitors is associated with improved overall survival in adult cancers: data mining of 1385 electronic patient records.

BACKGROUND: Dysthyroidism (DT) is a common toxicity of immune checkpoint inhibitors (ICIs) and prior work suggests that dysthyroidism (DT) might be associated with ICI efficacy. PATIENTS AND METHODS: ConSoRe, a new generation data mining solution, was used in this retrospective study, to extract data from electronic patient records of adult cancer patients treated with ICI at Institut Paoli-Calmettes (Marseille, France). Every DT was verified and only ICI-induced DT was retained. Survival analyses were performed by Kaplan-Meier method (log-rank test) and Cox model. To account for immortal time bias, a conditional landmark analysis was performed (2 months and 6 months), together with a time-varying Cox model. RESULTS: Data extraction identified 1385 patients treated with ICI between 2011 and 2021. DT was associated with improved overall survival (OS) (HR 0.46, (95% CI 0.33 to 0.65), p<0.001), with a median OS of 35.3 months in DT group vs 15.4 months in non-DT group (NDT). Survival impact of DT was consistent using a 6-month landmark analysis with a median OS of 36.7 months (95% CI 29.4 to not reported) in the DT group vs 25.5 months (95% CI 22.8 to 27.8) in the NDT group. In multivariate analysis, DT was independently associated with improved OS (HR 0.49, 95% CI 0.35 to 0.69, p=0.001). After adjustment in time-varying Cox model, this association remained significant (adjusted HR 0.64, 95% CI 0.45 to 0.90, p=0.010). Moreover, patients with DT and additional immune-related adverse event had increased OS compared with patients with isolated DT, with median OS of 38.8 months vs 21.4 months, respectively. CONCLUSION: Data mining identified a large number of patients with ICI-induced DT, which was associated with improved OS accounting for immortal time bias.

Prognostic Immune Effector Signature in Adult Acute Lymphoblastic Leukemia Patients Is Dominated by γδ T Cells.

The success of immunotherapy has highlighted the critical role of the immune microenvironment in acute lymphoblastic leukemia (ALL); however, the immune landscape in ALL remains incompletely understood and most studies have focused on conventional T cells or NK cells. This study investigated the prognostic impact of circulating γδ T-cell alterations using high-dimensional analysis in a cohort of newly diagnosed adult ALL patients (10 B-ALL; 9 Philadelphia+ ALL; 9 T-ALL). Our analysis revealed common alterations in CD8+ T cells and γδ T cells of relapsed patients, including accumulation of early stage differentiation and increased expression of BTLA and CD73. We demonstrated that the circulating γδ T-cell signature was the most discriminating between relapsed and disease-free groups. In addition, Vδ2 T-cell alterations strongly discriminated patients by relapse status. Taken together, these data highlight the role of ɣδ T cells in adult ALL patients, among whom Vδ2 T cells may be a pivotal contributor to T-cell immunity in ALL. Our findings provide a strong rationale for further monitoring and potentiating Vδ2 T cells in ALL, including in the autologous setting.

CD25high Effector Regulatory T Cells Hamper Responses to PD-1 Blockade in Triple-Negative Breast Cancer.

Regulatory T cells (Treg) impede effective antitumor immunity. However, the role of Tregs in the clinical outcomes of patients with triple-negative breast cancer (TNBC) remains controversial. Here, we found that an immunosuppressive TNBC microenvironment is marked by an imbalance between effector αßCD8+ T cells and Tregs harboring hallmarks of highly suppressive effector Tregs (eTreg). Intratumoral eTregs strongly expressed PD-1 and persisted in patients with TNBC resistant to PD-1 blockade. Importantly, CD25 was the most selective surface marker of eTregs in primary TNBC and metastases compared with other candidate targets for eTreg depletion currently being evaluated in trials for patients with advanced TNBC. In a syngeneic TNBC model, the use of Fc-optimized, IL2 sparing, anti-CD25 antibodies synergized with PD-1 blockade to promote systemic antitumor immunity and durable tumor growth control by increasing effector αßCD8+ T-cell/Treg ratios in tumors and in the periphery. Together, this study provides the rationale for the clinical translation of anti-CD25 therapy to improve PD-1 blockade responses in patients with TNBC. SIGNIFICANCE: An imbalance between effector CD8+ T cells and CD25high effector Tregs marks immunosuppressive microenvironments in αPD-1-resistant TNBC and can be reversed through effector Treg depletion to increase αPD-1 efficacy.

Anti-HVEM mAb therapy improves antitumoral immunity both in vitro and in vivo, in a novel transgenic mouse model expressing human HVEM and BTLA molecules challenged with HVEM expressing tumors.

BACKGROUND: Tumor necrosis factor superfamily member 14 (TNFRSF14)/herpes virus entry mediator (HVEM) is the ligand for B and T lymphocyte attenuator (BTLA) and CD160-negative immune co-signaling molecules as well as viral proteins. Its expression is dysregulated with an overexpression in tumors and a connection with tumors of adverse prognosis. METHODS: We developed C57BL/6 mouse models co-expressing human (hu)BTLA and huHVEM as well as antagonistic monoclonal antibodies (mAbs) that completely prevent the interactions of HVEM with its ligands. RESULTS: Here, we show that the anti-HVEM18-10 mAb increases primary human αß-T cells activity alone (CIS-activity) or in the presence of HVEM-expressing lung or colorectal cancer cells in vitro (TRANS-activity). Anti-HVEM18-10 synergizes with antiprogrammed death-ligand 1 (anti-PD-L1) mAb to activate T cells in the presence of PD-L1-positive tumors, but is sufficient to trigger T cell activation in the presence of PD-L1-negative cells. In order to better understand HVEM18-10 effects in vivo and especially disentangle its CIS and TRANS effects, we developed a knockin (KI) mouse model expressing human BTLA (huBTLA+/+) and a KI mouse model expressing both huBTLA+/+/huHVEM+/+ (double KI (DKI)). In vivo preclinical experiments performed in both mouse models showed that HVEM18-10 treatment was efficient to decrease human HVEM+ tumor growth. In the DKI model, anti-HVEM18-10 treatment induces a decrease of exhausted CD8+ T cells and regulatory T cells and an increase of effector memory CD4+ T cells within the tumor. Interestingly, mice which completely rejected tumors (±20%) did not develop tumors on rechallenge in both settings, therefore showing a marked T cell-memory phenotype effect. CONCLUSIONS: Altogether, our preclinical models validate anti-HVEM18-10 as a promising therapeutic antibody to use in clinics as a monotherapy or in combination with existing immunotherapies (antiprogrammed cell death protein 1/anti-PD-L1/anti-cytotoxic T-lymphocyte antigen-4 (CTLA-4)).

Disruption of endosomal trafficking with EGA alters TLR9 cytokine response in human plasmacytoid dendritic cells.

Plasmacytoid dendritic cells (pDCs) exhibit bifurcated cytokine responses to TLR9 agonists, an IRF7-mediated type 1 IFN response or a pro-inflammatory cytokine response via the activation of NF-κB. This bifurcated response has been hypothesized to result from either distinct signaling endosomes or endo-lysosomal trafficking delay of TLR9 agonists allowing for autocrine signaling to affect outcomes. Utilizing the late endosome trafficking inhibitor, EGA, we assessed the bifurcated cytokine responses of pDCs to TLR9 stimulation. EGA treatment of pDCs diminished both IFNα and pro-inflammatory cytokine expression induced by CpG DNAs (D- and K-type), CpG-DNAs complexed with DOTAP, and genomic DNAs complexed with LL37. Mechanistically, EGA suppressed phosphorylation of IKKα/ß, STAT1, Akt, and p38, and decreased colocalization of CpG oligodeoxynucleotides with LAMP+ endo-lysosomes. EGA also diminished type 1 IFN expression by pDCs from systemic lupus erythematosus patients. Therefore, our findings help understand mechanisms for the bifurcated cytokine responses by pDCs and support future examination of the potential benefit of EGA in treating type 1 IFN-associated inflammatory diseases in the future.

CD5 expression by dendritic cells directs T cell immunity and sustains immunotherapy responses.

The induction of proinflammatory T cells by dendritic cell (DC) subtypes is critical for antitumor responses and effective immune checkpoint blockade (ICB) therapy. Here, we show that human CD1c+CD5+ DCs are reduced in melanoma-affected lymph nodes, with CD5 expression on DCs correlating with patient survival. Activating CD5 on DCs enhanced T cell priming and improved survival after ICB therapy. CD5+ DC numbers increased during ICB therapy, and low interleukin-6 (IL-6) concentrations promoted their de novo differentiation. Mechanistically, CD5 expression by DCs was required to generate optimally protective CD5hi T helper and CD8+ T cells; further, deletion of CD5 from T cells dampened tumor elimination in response to ICB therapy in vivo. Thus, CD5+ DCs are an essential component of optimal ICB therapy.

Tumor associated macrophage in HPV+ tumors: Between immunosuppression and inflammation.

Over the past few decades, with the rise of immunotherapies, tumor infiltrating immune cells were increasingly investigated. Indeed, they may represent biomarkers for patient outcome prediction, they may bear immune checkpoint markers that can be targeted by therapeutic antibodies and mechanistic studies may reveal how to tweak their activation profile so that we can re-direct them towards tumor cells. Macrophages possess a central place in tissue homeostasis for tissue remodeling and cleaning, transformed cell elimination, phagocytosis and regulation of inflammation via cytokine production. All these functions allow the discovery of approaches to target Tumor Associated Macrophages (TAMs) using immunotherapies. Indeed, TAMs express known immune checkpoint markers such as PD-L1, CD40, Sirp-α and markers such as CD163, CD204, TREM2, TREM1 associated with prognosis. In the context of therapies TAM may participate to antibody dependent cell phagocytosis (ADCP) thanks to FCγ-Receptors. Here, we will review the recent literature on TAMs in the specific context of HPV+ tumors. Indeed, HPV infection of mucosal tissue may lead to head and neck, cervical, penile, anal and vaginal cancers. HPV+ tumors exhibit a higher immune cell infiltrate, which relies on inflammation, immunosuppression and anti-viral response. In this context, and considering the many functions on macrophages, we will show the versatility of TAMs in a tumor microenvironment with viral infection features.

High-throughput mass cytometry staining for deep phenotyping of human natural killer cells.

This protocol details the step-by-step procedure for in-depth immune phenotyping of peripheral blood natural killer (NK) cells from clinical samples by mass cytometry. The protocol consists of three main steps: PBMC incubation with a mix of metal-conjugated antibodies for extracellular phenotyping followed by fixation, permeabilization and incubation with a mix of metal-conjugated antibodies for staining of intracellular proteins, and sample acquisition on a mass cytometer. High-dimensional analysis enables the visualization of NK cell subsets and their phenotypical characteristics. For complete details on the use and execution of this protocol, please refer to Chretien et al. (2021).

Mass Cytometry Reveals Classical Monocytes, NK Cells, and ICOS+ CD4+ T Cells Associated with Pembrolizumab Efficacy in Patients with Lung Cancer.

PURPOSE: Immune checkpoint inhibitors (ICI) have revolutionized the treatment of non-small cell lung cancer (NSCLC), but predictive biomarkers of their efficacy are imperfect. The primary objective is to evaluate circulating immune predictors of pembrolizumab efficacy in patients with advanced NSCLC. EXPERIMENTAL DESIGN: We used high-dimensional mass cytometry (CyTOF) in baseline blood samples of patients with advanced NSCLC treated with pembrolizumab. CyTOF data were analyzed by machine-learning algorithms (Citrus, tSNE) and confirmed by manual gating followed by principal component analysis (between-group analysis). RESULTS: We analyzed 27 patients from the seminal KEYNOTE-001 study (median follow-up of 60.6 months). We demonstrate that blood baseline frequencies of classical monocytes, natural killer (NK) cells, and ICOS+ CD4+ T cells are significantly associated with improved objective response rates, progression-free survival, and overall survival (OS). In addition, we report that a baseline immune peripheral score combining these three populations strongly predicts pembrolizumab efficacy (OS: HR = 0.25; 95% confidence interval = 0.12-0.51; P < 0.0001). CONCLUSIONS: As this immune monitoring is easy in routine practice, we anticipate our findings may improve prediction of ICI benefit in patients with advanced NSCLC.

Therapeutic Targeting of Tumor-Infiltrating Regulatory T Cells in Breast Cancer.

Regulatory T cells (Treg) are an immunosuppressive subtype of CD4+ T cells essential for maintaining self-tolerance in physiological settings. Tregs also abundantly infiltrate inflamed tumor tissues, impeding the host's antitumor immune response and contributing to tumor growth and metastasis. In breast cancers, subsets of Tregs express highly immunosuppressive effector phenotypes that favor tumorigenesis, progression, and resistance to immune-checkpoint inhibitor therapies. Tregs share phenotypic features with cytotoxic lymphocytes, rendering them difficult to inhibit without compromising productive antitumor immunity. In addition, systemic targeting of Tregs causes serious autoimmune adverse events in patients with cancer. Hence, the identification of candidate targets or methodologies allowing the specific elimination of tumor antigen-specific Tregs, including tumor-infiltrating Tregs, is a prerequisite for developing efficient and safe combinatorial immunotherapeutic strategies in breast cancers. To date, numerous preclinical studies have demonstrated that specific targeting of breast tumor-infiltrating Tregs restores a competent antitumor immune response and improves responses to immune-checkpoint inhibitors such as PD-1/PD-L1 blockade. Herein, we discuss major candidate molecules for Treg-targeted therapeutic strategies in breast cancers, detailing the pros and cons of various approaches, including mAb-mediated depletion, homeostasis destabilization, and functional blockade.

BTLA-HVEM Couple in Health and Diseases: Insights for Immunotherapy in Lung Cancer.

Lung cancer is the leading cause of cancer deaths worldwide. Immunotherapies (IT) have been rapidly approved for lung cancer treatment after the spectacular results in melanoma. Responses to the currently used checkpoint inhibitors are strikingly good especially in metastatic diseases. However, durable responses are observed in only 25% of cases. Consequently, there is an urgent need for new immunotherapy targets. Among the multiple checkpoints involved in the tumor immune escape, the BTLA-HVEM couple appears to be a promising target. BTLA (B- and T- Lymphocyte Attenuator) is a co-inhibitory receptor mainly expressed by B and T cells, repressing the activation signal transduction. BTLA shares similarities with other immune checkpoints such as PD-1 and CTLA-4 which are the targets of the currently used immunotherapies. Furthermore, BTLA expression points out terminally exhausted and dysfunctional lymphocytes, and correlates with lung cancer progression. The ligand of BTLA is HVEM (Herpes Virus Entry Mediator) which belongs to the TNF receptor family. Often described as a molecular switch, HVEM is constitutively expressed by many cells, including cells from tumor and healthy tissues. In addition, HVEM seems to be involved in tumor immuno-evasion, especially in lung tumors lacking PD-L1 expression. Here, we propose to review the role of BTLA-HVEM in immuno-escape in order to highlight its potential for designing new immunotherapies.

BTN2A1, an immune checkpoint targeting Vγ9Vδ2 T cell cytotoxicity against malignant cells.

The anti-tumor response of Vγ9Vδ2 T cells requires the sensing of accumulated phosphoantigens (pAgs) bound intracellularly to butyrophilin 3A1 (BTN3A1). In this study, we show that butyrophilin 2A1 (BTN2A1) is required for BTN3A-mediated Vγ9Vδ2 T cell cytotoxicity against cancer cells, and that expression of the BTN2A1/BTN3A1 complex is sufficient to trigger Vγ9Vδ2 TCR activation. Also, BTN2A1 interacts with all isoforms of BTN3A (BTN3A1, BTN3A2, BTN3A3), which appears to be a rate-limiting factor to BTN2A1 export to the plasma membrane. BTN2A1/BTN3A1 interaction is enhanced by pAgs and, strikingly, B30.2 domains of both proteins are required for pAg responsiveness. BTN2A1 expression in cancer cells correlates with bisphosphonate-induced Vγ9Vδ2 T cell cytotoxicity. Vγ9Vδ2 T cell killing of cancer cells is modulated by anti-BTN2A1 monoclonal antibodies (mAbs), whose action relies on the inhibition of BTN2A1 binding to the Vγ9Vδ2TCR. This demonstrates the potential of BTN2A1 as a therapeutic target and adds to the emerging butyrophilin-family cooperation pathway in γδ T cell activation.

Endometrial Carcinoma: Immune Microenvironment and Emerging Treatments in Immuno-Oncology.

Endometrial cancer (EC) can easily be cured when diagnosed at an early stage. However, advanced and metastatic EC is a common disease, affecting more than 15,000 patients per year in the United Sates. Only limited treatment options were available until recently, with a taxane-platinum combination as the gold standard in first-line setting and no efficient second-line chemotherapy or hormone therapy. EC can be split into four molecular subtypes, including hypermutated cases with POLE mutations and 25-30% harboring a microsatellite instability (MSI) phenotype with mismatch repair deficiency (dMMR). These tumors display a high load of frameshift mutations, leading to increased expression of neoantigens that can be targeted by the immune system, including (but not limited) to T-cell response. Recent data have demonstrated this impact of programmed death 1 and programmed death ligand 1 (PD-1/PD-L1) inhibitors on chemo-resistant metastatic EC. The uncontrolled KEYNOTE-158 and GARNET trials have shown high response rates with pembrolizumab and dostarlimab in chemoresistant MSI-high tumors. Most responders experiment long responses that last more than one year. Similar, encouraging results were obtained for MMR proficient (MMRp) cases treated with a combination of pembrolizumab and the angiogenesis inhibitor lenvatinib. Approvals have, thus, been obtained or are underway for EC with immune checkpoint inhibitors (ICI) used as monotherapy, and in combination with antiangiogenic agents. Combinations with other targeted therapies are under evaluation and randomized studies are ongoing to explore the impact of ICI-chemotherapy triplets in first-line setting. We summarize in this review the current knowledge of the immune environment of EC, both for MMRd and MMRp tumors. We also detail the main clinical data regarding PD-1/PD-L1 inhibitors and discuss the next steps of development for immunotherapy, including various ICI-based combinations planned to limit resistance to immunotherapy.

High-dimensional mass cytometry analysis of NK cell alterations in AML identifies a subgroup with adverse clinical outcome.

Natural killer (NK) cells are major antileukemic immune effectors. Leukemic blasts have a negative impact on NK cell function and promote the emergence of phenotypically and functionally impaired NK cells. In the current work, we highlight an accumulation of CD56-CD16+ unconventional NK cells in acute myeloid leukemia (AML), an aberrant subset initially described as being elevated in patients chronically infected with HIV-1. Deep phenotyping of NK cells was performed using peripheral blood from patients with newly diagnosed AML (n = 48, HEMATOBIO cohort, NCT02320656) and healthy subjects (n = 18) by mass cytometry. We showed evidence of a moderate to drastic accumulation of CD56-CD16+ unconventional NK cells in 27% of patients. These NK cells displayed decreased expression of NKG2A as well as the triggering receptors NKp30 and NKp46, in line with previous observations in HIV-infected patients. High-dimensional characterization of these NK cells highlighted a decreased expression of three additional major triggering receptors required for NK cell activation, NKG2D, DNAM-1, and CD96. A high proportion of CD56-CD16+ NK cells at diagnosis was associated with an adverse clinical outcome and decreased overall survival (HR = 0.13; P = 0.0002) and event-free survival (HR = 0.33; P = 0.018) and retained statistical significance in multivariate analysis. Pseudotime analysis of the NK cell compartment highlighted a disruption of the maturation process, with a bifurcation from conventional NK cells toward CD56-CD16+ NK cells. Overall, our data suggest that the accumulation of CD56-CD16+ NK cells may be the consequence of immune escape from innate immunity during AML progression.