Selective SIRPα blockade reverses tumor T cell exclusion and overcomes cancer immunotherapy resistance

T cell exclusion causes resistance to cancer immunotherapies via immune checkpoint blockade (ICB). Myeloid cells contribute to resistance by expressing signal regulatory protein-α (SIRPα), an inhibitory membrane receptor that interacts with ubiquitous receptor CD47 to control macrophage phagocytosis in the tumor microenvironment. Although CD47/SIRPα-targeting drugs have been assessed in preclinical models, the therapeutic benefit of selectively blocking SIRPα, and not SIRPγ/CD47, in humans remains unknown. We report a potent synergy between selective SIRPα blockade and ICB in increasing memory T cell responses and reverting exclusion in syngeneic and orthotopic tumor models. Selective SIRPα blockade stimulated tumor nest T cell recruitment by restoring murine and human macrophage chemokine secretion and increased anti-tumor T cell responses by promoting tumor-antigen crosspresentation by dendritic cells. However, nonselective SIRPα/SIRPγ blockade targeting CD47 impaired human T cell activation, proliferation, and endothelial transmigration. Selective SIRPα inhibition opens an attractive avenue to overcoming ICB resistance in patients with elevated myeloid cell infiltration in solid tumors.

Digestive involvement in a severe form of Snyder-Robinson syndrome: Possible expansion of the phenotype

Snyder-Robinson syndrome (OMIM #309583) is a rare X-linked condition, caused by mutation in the SMS gene (MIM *300105), characterized by a wide spectrum of clinical signs including developmental delay, epilepsy, asthenic habitus, dysmorphism, osteopenia, and renal or genital anomalies. Here we describe two maternal half-brothers who both presented with severe neurodevelopmental delay, seizures, hearing loss, facial dysmorphism, renal and ophthalmologic anomalies, failure to thrive and premature death. A novel p.(Gly203Asp) variant was found at the hemizygous state in the two boys, and an elevated Spermidine/Spermine ratio confirmed the diagnosis of Snyder-Robinson syndrome. One of the brothers presented with gastrointestinal symptoms, with jejunal stenosis, enteral feeding intolerance, failure to thrive due to a dysfunctional gastrointestinal system, cholestasis and exocrine pancreatic insufficiency. Although more studies will be needed to understand its mechanisms, this observation lends further support to the possibility of severe digestive involvement in Snyder Robinson syndrome.

Lactic Acidosis Together with GM-CSF and M-CSF Induces Human Macrophages toward an Inflammatory Protumor Phenotype

In established tumors, tumor-associated macrophages (TAM) orchestrate nonresolving cancer-related inflammation and produce mediators favoring tumor growth, metastasis, and angiogenesis. However, the factors conferring inflammatory and protumor properties on human macrophages remain largely unknown. Most solid tumors have high lactate content. We therefore analyzed the impact of lactate on human monocyte differentiation. We report that prolonged lactic acidosis induces the differentiation of monocytes into macrophages with a phenotype including protumor and inflammatory characteristics. These cells produce tumor growth factors, inflammatory cytokines, and chemokines as well as low amounts of IL10. These effects of lactate require its metabolism and are associated with hypoxia-inducible factor-1α stabilization. The expression of some lactate-induced genes is dependent on autocrine M-CSF consumption. Finally, TAMs with protumor and inflammatory characteristics (VEGF^high CXCL8⁺ IL1β⁺) are found in solid ovarian tumors. These results show that tumor-derived lactate links the protumor features of TAMs with their inflammatory properties. Treatments that reduce tumor glycolysis or tumor-associated acidosis may help combat cancer.

Les CAR-T cells, des cellules tueuses spécifiques d’antigènes tumoraux

Les lymphocytes T présentent des fonctions lytiques puissantes et leur adressage spécifique aux cellules tumorales afin de les détruire est un enjeu majeur. Leur ingénierie par transfert d’une construction génétique codant un fragment d’anticorps spécifique de la molécule CD19, exprimée par les lymphocytes B, fusionné à une unité de transduction d’un signal T a conduit à des résultats cliniques importants dans des formes avancées de lymphomes. Ces lymphocytes T modifiés, appelés CAR-T cells, ou plus simplement CAR pour chimeric antigen receptor, ont reçu une approbation par la Food and drug administration américaine en 2017 pour les deux premiers médicaments de thérapie cellulaire : le Kymriah™ et le Yescarta™. Ces CAR, conçus pour le traitement d’hémopathies malignes, permettent d’envisager la construction d’autres CAR dirigés, eux, contre des tumeurs solides. De nouvelles générations de CAR visent à mieux contrôler leur prolifération et à améliorer leurs fonctions in vivo grâce à la mise en place de mécanismes d’inactivation inductibles. Le développement des multi-CAR, des CAR spécifiques de plusieurs cibles, et leur combinaison aux inhibiteurs de points de contrôle immunitaires ouvrent une nouvelle ère pour l’immunothérapie des tumeurs.

Eomesodermin together with KIR/NKG2A membrane receptors and CD49d as an useful strategy to identify NK-like CD8(+) T cells with innate features in humans: focusing on cancer diseases

Among the burgeoning family of unconventional T cells, innate-like CD8(+) T cells bear a memory phenotype without having encountered a foreign antigen and can respond to innate-like IL-12+IL-18 stimulation. Although the concept of innate memory (IM) CD8(+) T cells is now well-established in mice, whether an equivalent memory NK-like T-cell population exists in humans remains under debate. We recently reported that CD8(+) T cells responding to innate-like IL-12+IL-18 stimulation and co-expressing the transcription factor Eomesodermin (Eomes) and KIR/NKG2A membrane receptors with a memory/EMRA phenotype may represent a new, functionally distinct innate T cell subset in humans.

Here, we proposed Eomes together with KIR/NKG2A and CD49d as a signature to standardize the identification of this innate CD8(+) T-cell subset in humans. Focusing on cancer diseases, we have provided new insights into the potential role of these IM CD8(+) T cells in a physiopathological context in humans. Based on empirical data obtained in cases of chronic myeloid leukemia, a myeloproliferative syndrome controlled by the immune system, and in solid tumors, we have observed both the possible contribution of IM CD8(+) T cells to cancer disease control and their susceptibility to tumor immune subversion. Finally, we have investigated the involvement of IL-4 and IL-15 in the generation of the IM CD8(+) T cell pool and its dependency on promyelocytic leukemia zinc finger (PLZF)-expressing invariant Natural Killer T (iNKT) cells.

All in all, this study significantly contributes to understanding of the physiopathological role of NK-like CD8(+) T cells in humans and raises the question of the possible involvement of an iNKT/IM CD8(+) T cell axis in cancer.

Phenotype of NK-Like CD8(+) T Cells with Innate Features in Humans and Their Relevance in Cancer Diseases

Unconventional T cells are defined by their capacity to respond to signals other than the well-known complex of peptides and major histocompatibility complex proteins. Among the burgeoning family of unconventional T cells, innate-like CD8(+) T cells in the mouse were discovered in the early 2000s. This subset of CD8(+) T cells bears a memory phenotype without having encountered a foreign antigen and can respond to innate-like IL-12 + IL-18 stimulation. Although the concept of innate memory CD8(+) T cells is now well established in mice, whether an equivalent memory NK-like T-cell population exists in humans remains under debate. We recently reported that CD8(+) T cells responding to innate-like IL-12 + IL-18 stimulation and co-expressing the transcription factor Eomesodermin (Eomes) and KIR/NKG2A membrane receptors with a memory/EMRA phenotype may represent a new, functionally distinct innate T cell subset in humans. In this review, after a summary on the known innate CD8(+) T-cell features in the mouse, we propose Eomes together with KIR/NKG2A and CD49d as a signature to standardize the identification of this innate CD8(+) T-cell subset in humans. Next, we discuss IL-4 and IL-15 involvement in the generation of innate CD8(+) T cells and particularly its possible dependency on the promyelocytic leukemia zinc-finger factor expressing iNKT cells, an innate T cell subset well documented for its susceptibility to tumor immune subversion. After that, focusing on cancer diseases, we provide new insights into the potential role of these innate CD8(+) T cells in a physiopathological context in humans. Based on empirical data obtained in cases of chronic myeloid leukemia, a myeloproliferative syndrome controlled by the immune system, and in solid tumors, we observe both the possible contribution of innate CD8(+) T cells to cancer disease control and their susceptibility to tumor immune subversion. Finally, we note that during tumor progression, innate CD8(+) T lymphocytes could be controlled by immune checkpoints. This study significantly contributes to understanding of the role of NK-like CD8(+) T cells and raises the question of the possible involvement of an iNKT/innate CD8(+) T cell axis in cancer.

Metabolic Signature of Remote Ischemic Preconditioning Involving a Cocktail of Amino Acids and Biogenic Amines

Background

Remote ischemic preconditioning (RIPC) is an attractive therapeutic procedure for protecting the heart against ischemia/reperfusion injury. Despite evidence of humoral mediators transported through the circulation playing a critical role, their actual identities so far remain unknown. We sought to identify plasmatic RIPC‐induced metabolites that may play a role.

Methods and Results

Rat plasma samples from RIPC and control groups were analyzed using a targeted metabolomic approach aimed at measuring 188 metabolites. Principal component analysis and orthogonal partial least‐squares discriminant analysis were used to identify the metabolites that discriminated between groups. Plasma samples from 50 patients subjected to RIPC were secondarily explored to confirm the results obtained in rats. Finally, a combination of the metabolites that were significantly increased in both rat and human plasma was injected prior to myocardial ischemia/reperfusion in rats. In the rat samples, 124 molecules were accurately quantified. Six metabolites (ornithine, glycine, kynurenine, spermine, carnosine, and serotonin) were the most significant variables for marked differentiation between the RIPC and control groups. In human plasma, analysis confirmed ornithine decrease and kynurenine and glycine increase following RIPC. Injection of the glycine and kynurenine alone or in combination replicated the protective effects of RIPC seen in rats.

Conclusions

We have hereby reported significant variations in a cocktail of amino acids and biogenic amines after remote ischemic preconditioning in both rat and human plasma.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01390129.

The ecto-ATPDase CD39 is involved in the acquisition of the immunoregulatory phenotype by M-CSF-macrophages and ovarian cancer tumor-associated macrophages: Regulatory role of IL-27

Tumor-associated macrophages (TAM) are immunosuppressive cells that can massively accumulate in the tumor microenvironment. In patients with ovarian cancer, their density is correlated with poor prognosis. Targeting mediators that control the generation or the differentiation of immunoregulatory macrophages represents a therapeutic challenge to overcome tumor-associated immunosuppression. The ectonucleotidase CD39 hydrolyzes ATP into extracellular adenosine that exhibits potent immunosuppressive properties when signaling through the A2A adenosine receptor. We report here that CD14(+) CD163(+) TAM isolated from ovarian cancer patients and macrophages generated in vitro with M-CSF, express high levels of the membrane ectonucleotidase CD39 compared to classically activated macrophages. The CD39 inhibitor POM-1 and adenosine deaminase (ADA) diminished some of the immunosuppressive functions of CD14(high) CD163(high) CD39(high) macrophages, such as IL-10 secretion. We identified the cytokine IL-27, secreted by tumor-infiltrating neutrophils, located close to infiltrating CD163(+) macrophages, as a major rheostat of CD39 expression and consequently, on the acquisition of immunoregulatory properties by macrophages. Accordingly, the depletion of IL-27 downregulated CD39 and PD-L1 expression as well as IL-10 secretion by M-CSF-macrophages. Collectively, these data suggest that CD39, drived by IL-27 and CD115 ligands in ovarian cancer, maintains the immunosuppressive phenotype of TAM. This work brings new information on the acquisition of immunosuppressive properties by tumor-infiltrating macrophages.

Involvement of purinergic receptors and NOD-like receptor-family protein 3-inflammasome pathway in the adenosine triphosphate-induced cytokine release from macrophages

Adenosine triphosphate (ATP) has been described as a danger signal activating the NOD-like receptor-family protein 3 (NLRP3)-inflammasome leading to the pro-inflammatory cytokine, interleukin (IL)-1β, release in the lung. The NLRP3-inflammasome pathway has been previously described to be involved in experimental collagen deposition and the development of pulmonary fibrosis. The aim of the present study was to investigate the role of the NLRP3 inflammasome pathway and P2X7 purinergic receptor in the activation of human macrophages in vitro by ATP. We showed that adenosine 5'-[γ-thio]triphosphate tetralithium salt (ATPγS) and 2',3'-O-(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP), two stable analogs of ATP, are able to potentiate the release of IL-1β from human monocyte-derived macrophages induced by low concentration of lipopolysaccharide (LPS). However, in the same conditions no increase in IL-1α and IL-6 was observed. Immunochemistry has shown that human macrophages natively express NLRP3 and purinergic P2X7 receptors (P2X7 R). NLRP3 and IL-1β mRNA expression were induced from LPS-primed macrophages, but also after 5-h treatment of BzATP as analysed by reverse transcription quantitative polymerase chain reaction. However, other inflammasome pathways (NLRP1, NLRP2, NLRC4, NLRP6 and AIM2) and P2X7 R were not induced by BzATP. We observed that P2X7 R antagonists, A-438079 and A-740003, were able to reduce the release of IL-1β, but not of IL-1α and IL-6 from macrophages stimulated by ATPγS or BzATP. The present results showed the involvement of the P2X7 R-NLRP3 inflammasome pathway in the secretion of IL-1β from ATP-stimulated human macrophages, and suggest that P2X7 R were not involved in IL-1α and IL-6 release. This study also points out that repression of the P2X7 R represents a novel potential therapeutic approach to control fibrosis in lung injury.

[Nectins and nectin-like receptors DNAM-1 and CRTAM: new ways for tumor escape]

Nectin and nectin-like (Necl) are cell adhesion molecules expressed in various tumors. They were alternatively reported as involved in tumor suppressor or oncogenic functions that led to their use as histological or serological cancer markers. Gene inactivation in lung carcinoma but overexpression in leukemia were reported for Necl-2. DNAM-1 and CRTAM are emerging NK receptors of immune cells that were described to interact with nectin and Necl. DNAM-1, constitutively expressed by CD8(+) T cells, NK or γδ T lymphocytes, is a ligand of Necl-5. It participates to tumor immunosurveillance promoting Necl-5 expressing tumor cell lysis. CRTAM, only expressed after lymphocyte activation, is a ligand of Necl-2. Engagement of CRTAM with Necl-2 has opposite effects depending on the type of lymphocyte. For NK or CD8(+) T cells, it promotes cytotoxicity and IFNγ secretion favoring immunosurveillance. By contrast, CRTAM/Necl-2 interaction triggers cell death of activated TVg9Vd2 γδ T cells favoring immune escape. Nectin and Necl-mediated interactions appear to be crucial for the delicate balance between tumor escape and antitumor response.

[Immunotherapy in epithelial ovarian carcinoma: hope and reality]

INTRODUCTION

Epithelial ovarian carcinoma (EOC) has a worst prognosis with little progress in terms of survival for the last two decades. Immunology received little interest in EOC in the past, but now appears very important in the natural history of this cancer. This review is an EOC immunology state of art and focuses on the place of immunotherapy in future.

MATERIAL AND METHODS

A systematic review of published studies was performed. Medline baseline interrogation was performed with the following keywords: "Ovarian carinoma, immunotherapy, T-lymphocyte, regulator T-lymphocyte, dendritic cells, macrophage, antigen, chemotherapy, surgery, clinical trials". Identified publications (English or French) were assessed for the understanding of EOC immunology and the place of conventional treatment and immunotherapy strategy.

RESULTS

Intratumoral infiltration by immune cells is a strong prognotic factor in EOC. Surgery and chemotherapy in EOC decrease imunosuppression in patients. The antitumoral immunity is a part of the therapeutic action of surgery and chemotherapy. Until now, immunotherapy gave some disappointing results, but the new drugs that target the tolerogenic tumoral microenvironnement rise and give a new hope in the treatment of cancer.

CONCLUSION

Immunology controls the EOC natural history. The modulation of immunosuppressive microenvironment associated with the stimulation of antitumoral immunity could be the next revolution in the treatment of cancer.

Repeated systemic administrations of both aminobisphosphonates and human Vγ9Vδ2 T cells efficiently control tumor development in vivo

Peripheral Vγ9Vδ2 T lymphocytes compose a major γδ T cell subset in primates with broad reactivity against tumor cells. Vγ9Vδ2 T cells are specifically activated by phosphorylated isoprenoid pathway metabolites called "phosphoagonists." Accordingly, pharmacologic inhibitors of the mevalonate pathway, such as aminobisphosphonates (NBP) that upregulate the intracellular production of phosphoagonists, increase antitumor Vγ9Vδ2 T cell responses. Immunotherapeutic protocols exploiting GMP-grade agonist molecules targeting human Vγ9Vδ2 T lymphocytes have yielded promising, yet limited, signs of antitumor efficacy and therefore need to be improved for next-generation immunotherapies. In this study, we used a model of s.c. human tumor xenografts in severely immunodeficient mice to assess the antitumor efficacy of systemic NBP treatments when combined with the adoptive transfer of human Vγ9Vδ2 T cells. We show that infusion of Vγ9Vδ2 T cells, 24 h after systemic NBP treatment, efficiently delays tumor growth in mice. Importantly, our results indicate efficient but transient in vivo NBP-induced sensitization of tumor cells to human Vγ9Vδ2-T cell recognition. Accordingly, repeated and combined administrations of both NBP and γδ T cells yielded improved antitumor responses in vivo. Because Vγ9Vδ2 T cells show similar responsiveness toward both autologous and allogeneic tumors and are devoid of alloreactivity, these results provide preclinical proof of concept for optimized antitumor immunotherapies combining NBP treatment and adoptive transfer of allogeneic human γδ T cells.

A quantitative deficiency in peripheral blood Vγ9Vδ2 cells is a negative prognostic biomarker in ovarian cancer patients

Vγ9Vδ2 cells are cytotoxic T cells that are able to recognize epithelial ovarian carcinoma (EOC) cells. Therefore, Vγ9Vδ2 cell-based adoptive transfer is an attractive therapy for EOC. However, the inefficient ex vivo expansion after specific stimulation of Vγ9Vδ2 cells from some patients and the relationships between Vγ9Vδ2 cells and clinical course of EOC are issues that remain to be clarified. Herein, peripheral blood mononuclear cells (PBMCs) from 60 EOC patients were stimulated with bromohydrin pyrophosphate (BrHPP) or zoledronate, which are specific agonists of Vγ9Vδ2 cells. The compounds differed in their efficacies to induce ex vivo Vγ9Vδ2 PBMC expansion, but 16/60 samples remained inefficiently expanded with both stimuli. Interestingly, the Vγ9Vδ2 cells in these low-responding PBMCs displayed before expansion (ex vivo PBMCs) an altered production of the pro-inflammatory cytokines IFN-γ and TNF-α, a decreased naive fraction and a reduced frequency. No evidence of an involvement of CD4⁺CD25⁺Foxp3⁺ regulatory cells was observed. Importantly, our data also demonstrate that a Vγ9Vδ2 cell frequency of 0.35% or less in EOC PBMCs could be used to predict low responses to both BrHPP and zoledronate. Moreover, our data highlight that such a deficiency is not correlated with advanced EOC stages but is associated with more refractory states to platinum-based chemotherapy and is an independent predictor of shorter disease-free survival after treatment. These results are the first to suggest a potential contribution of Vγ9Vδ2 cells to the anti-tumor effects of chemotherapeutic agents and they strengthen interest in strategies that might increase Vγ9Vδ2 cells in cancer patients.

Sensitization of ovarian carcinoma cells with zoledronate restores the cytotoxic capacity of Vγ9Vδ2 T cells impaired by the prostaglandin E2 immunosuppressive factor: implications for immunotherapy

Epithelial ovarian cancer (EOC) usually spreads into the peritoneal cavity, thereby providing an opportunity for intraperitoneal adoptive immunotherapy with Vγ9Vδ2 T lymphocytes, a T cell subpopulation endowed with high lytic properties against tumor cells. However, previous studies have reported that Vγ9Vδ2 T cells fail to expand from peripheral blood mononuclear cells in one-third of patients with cancer. Here, from a cohort of 37 patients with EOC, a multiple correspondence analysis identified three populations, one of which was not suitable for Vγ9Vδ2 T-cell adoptive therapy. Interestingly, the ineligible patients were identified based on the frequency of Vγ9Vδ2 T cells in their peripheral blood and the patients' age. The average time to tumor recurrence was also found to be significantly different between the three populations, suggesting that the innate immune response is involved in EOC prognosis. A dramatic decrease in the lytic properties of Vγ9Vδ2 T cells occurred following incubation with ascitic supernatant and was found to be associated with reduced perforin/granzyme degranulation. Prostaglandin E2, but not IL-6, IL-10, VEGF or TGF-β, showed immunosuppressive effects in Vγ9Vδ2 T cells. Interestingly, our results emphasize that pretreating ovarian tumor cells with zoledronate partially reverses the immunosuppressive effects of ovarian cancer-associated ascites and restores a high level of lytic activity. These data sustain that optimal Vγ9Vδ2 T-cell adoptive immunotherapy previously requires counteracting the tumor immunosuppressive microenvironment. Altogether, our findings provide a rationale for clinically evaluating Vγ9Vδ2 T-cell adoptive immunotherapy with intraperitoneal carcinomatosis presensitization by zoledronate in patients with EOC.

Aminobisphosphonate-pretreated dendritic cells trigger successful Vgamma9Vdelta2 T cell amplification for immunotherapy in advanced cancer patients

Hepatocellular carcinoma (HCC) and colorectal carcinoma with hepatic metastases (mCRC) are cancers with poor prognosis and limited therapeutic options. New approaches are needed and adoptive immunotherapy with Vgamma9Vdelta2 T lymphocytes represents an attractive strategy. Indeed, Vgamma9Vdelta2 T cells were shown to exhibit efficient lytic activity against various human tumor cell lines, and in vitro Vgamma9Vdelta2 T expansion protocol based on single phosphoantigen stimulation could be easily performed for healthy donors. However, a low proliferative response of Vgamma9Vdelta2 T cells was observed in about half of the cancer patients, leading to an important limitation in the development of Vgamma9Vdelta2 T cell-based immunotherapy. Here, for the first time in the context of cancer patients, Vgamma9Vdelta2 T cell expansions were performed by co-culturing peripheral blood mononuclear cell (PBMCs) with autologous dendritic cells (DCs) pretreated with aminobisphosphonate zoledronate. For patients not responding to the conventional culture protocol, co-culture of PBMC with zoledronate-pretreated DCs induced strong cell expansion and allowed reaching a minimal rate of purity of 70% of Vgamma9Vdelta2 T cells. The potent immunostimulatory activity of zoledronate-treated DCs was associated with higher amount of isopentenyl pyrophosphate (IPP) in the culture and was correlated with better ability to activate Vgamma9Vdelta2 T cells as measured by IFN-gamma production. Moreover, we demonstrated that the cytotoxic level of Vgamma9Vdelta2 T cells against freshly autologous tumor cells isolated from patients could be significantly increased by pretreating the tumor cells with zoledronate. Thus, this method of generating Vgamma9Vdelta2 T cells leads eligible for Vgamma9Vdelta2 T cell adoptive immunotherapy the HCC and mCRC patients.

DNAX accessory molecule-1 (CD226) promotes human hepatocellular carcinoma cell lysis by Vgamma9Vdelta2 T cells

Human Vgamma9Vdelta2 T lymphocytes can be activated by nonpeptidic antigens such as the mevalonate pathway-derived isopentenyl pyrophosphate or synthetic phosphoantigen such as bromohydrin pyrophosphate. They display a strong cytotoxic activity against several tumor types, including hepatocellular carcinoma (HCC). Little is known about the mechanisms underlying Vgamma9Vdelta2 T-cell recognition of tumor cells, but there is strong evidence that activating NK receptors play a role in gammadelta T-cell cytotoxicity. In this study, we showed that the two NK receptors DNAX accessory molecule-1 (DNAM-1) and CD96 were expressed by Vgamma9Vdelta2 T cells. The ligands Nectin-like-5 specific of both DNAM-1 and CD96, and also Nectin-2, an additional ligand of DNAM-1, were present on all HCC cell lines analyzed. Furthermore, we demonstrated by mAb-mediated masking experiments that cytotoxicity against HCC cells as well as IFN-gamma production in gammadelta T cells were dependent on DNAM-1. Our experiments indicated that Nectin-like-5 but not Nectin-2 was involved in DNAM-1-dependent gammadelta T-cell functions. We did not reveal a role for CD96 in the killing of HCC cells. Finally, we showed by combined mAb-mediated blockade that DNAM-1 and NKG2D could cooperate in the cell lysis of HCC.

Vgamma9Vdelta2 T cell-mediated recognition of human solid tumors. Potential for immunotherapy of hepatocellular and colorectal carcinomas

INTRODUCTION

Vgamma9Vdelta2 T lymphocytes are reported to participate in the anti-tumor immune surveillance in human. They are known to recognize phosphoantigens and molecules expressed on cells undergoing neoplasic transformation. In this study, we investigated phenotype and anti-tumor cytotoxicity of ex vivo expanded Vgamma9Vdelta2 T cells in view of adoptive immunotherapy.

MATERIALS AND METHODS

Experiments were performed with peripheral blood samples from eleven patients [six colorectal carcinoma (CRC), four hepatocellular carcinoma (HCC), one sarcoma] and sixteen healthy donors.

RESULTS/DISCUSSION

Ex vivo expansion of Vgamma9Vdelta2 T cells could be achieved by a single dose of phosphoantigen, either bromohydrin pyrophosphate or zoledronate, and supported by exogenous IL-2. After 2 weeks, expanded Vgamma9Vdelta2 T lymphocytes acquired the effector memory phenotype CD45RA(-)CD45RO(high)CD27(-). They expressed NKG2D and CD161 and the proinflammatory CXCR3 and CCR5 chemokine receptors. Vgamma9Vdelta2 T cells displayed a strong lytic activity toward a broad panel of tumor cell lines or primary cultures. Interestingly, HCC and CRC primary cells could be lysed by autologous Vgamma9Vdelta2 T cells whereas autologous normal cells were not sensitive to the lysis. mAbs blocking assays demonstrated that TCR was the most important receptor involved in the lysis of tumor cells. However, NKG2D receptor could deliver a costimulatory signal enhancing the lysis of HCC and CRC tumors expressing MICA/B. Treatment of tumor cells by the mevalonate pathway inhibitor, zoledronate, enhanced the killing of both HCC and CRC. Expansion index of Vgamma9Vdelta2 T cells was in similar levels in healthy donors or in cancer patients and total expansion was suitable for adoptive immunotherapy.

CONCLUSION

These results provide a rationale for the clinical evaluation of Vgamma9Vdelta2 T lymphocytes in HCC and CRC.

Activation of tumor-specific T cells by dendritic cells expressing the NY-ESO-1 antigen after transfection with the cationic lipophosphoramide KLN5

BACKGROUND

Genetic modification of human monocyte-derived dendritic cells (DC) with cDNA sequences encoding tumor-associated antigens (TAA) is a promising strategy for cancer immunotherapy. The present study aimed to develop a nonviral gene transfer method based on the use of the cationic lipophosphoramide reagent, KLN-5, as an alternative to the commonly used viral vectors.

METHODS

First, the efficiency of KLN5 for gene transfection into DC was investigated using the green fluorescent protein (GFP) reporter gene. The highest transfection efficiency/cell viability ratio was determined by flow cytometry. Next, DC were transfected with a plasmid encoding NY-ESO-1, a TAA expressed in numerous cancers, according to the transfection protocol previously established with the GFP reporter. Transfected DC were then co-cultured with a CD8+ NY-ESO-1 specific HLA-A*02.01 T cell clone to control their ability to correctly process and present the corresponding epitope in the HLA-A*02.01 context. Finally, T cell activation was assessed via flow cytometry-based detection of interferon-gamma production.

RESULTS

An optimal KLN5/plasmid DNA ratio allowing both significant transgene expression and high viability of DC could be determined. Under the established experimental conditions, antigen processing and presentation of the immunodominant (SLLMWITQC(157-165)) epitope in the HLA-A*0201 context was demonstrated by activation of the NY-ESO-1-specific CD8+ T cell clone.

CONCLUSIONS

KLN5-based gene transfection into DC allows the efficient induction of TAA presentation and may thus represent a novel attractive nonviral approach for cancer vaccination.

[Immune anticancer response: recent advances in the treatment of renal cell carcinoma]

Recent advances in the field of immunobiology have provided many opportunities for anticancer-immunotherapy. Because they express tu-mor antigen, tumor cells can be kill by T cells. Renal Cell Carcinoma (RCC) is an immunogenic tumor and metastatic RCC is presently treated by cytokines. Anticancer immunity may be achieved by different strategies: allogeneic hematopoietic cell transplantation, vaccination with peptides, vaccination with loaded dendritic cells or adoptive cellular therapy in which specific T cells are isolated and expanded in vitro and then infused to patients. In our group, we have chosen the adoptive transfer of in vitro activated T cells with autologous tumor antigen loaded dendritic cells. To determine the best strategy of anticancer-immunotherapy, we need rigorous control of the specificity and the phenotype of the cell therapy product linked with the immunological status of the patient (before and after infusion) and with the clinical response.