Trial Watch: Immunostimulatory monoclonal antibodies for oncological indications

Synthetic dual co-stimulation increases the potency of HIT and TCR-targeted cell therapies

Chimeric antigen receptor T cells have dramatically improved the treatment of hematologic malignancies. T cell antigen receptor (TCR)-based cell therapies are yet to achieve comparable outcomes. Importantly, chimeric antigen receptors not only target selected antigens but also reprogram T cell functions through the co-stimulatory pathways that they engage upon antigen recognition. We show here that a fusion receptor comprising the CD80 ectodomain and the 4-1BB cytoplasmic domain, termed 80BB, acts as both a ligand and a receptor to engage the CD28 and 4-1BB pathways, thereby increasing the antitumor potency of human leukocyte antigen-independent TCR (HIT) receptor- or TCR-engineered T cells and tumor-infiltrating lymphocytes. Furthermore, 80BB serves as a switch receptor that provides agonistic 4-1BB co-stimulation upon its ligation by the inhibitory CTLA4 molecule. By combining multiple co-stimulatory features in a single antigen-agnostic synthetic receptor, 80BB is a promising tool to sustain CD3-dependent T cell responses in a wide range of targeted immunotherapies.

Comprehensive analysis of the cancer driver genes in breast cancer demonstrates their roles in cancer prognosis and tumor microenvironment

Background

Breast cancer is the most common malignancy in women. Cancer driver gene-mediated alterations in the tumor microenvironment are critical factors affecting the biological behavior of breast cancer. The purpose of this study was to identify the expression characteristics and prognostic value of cancer driver genes in breast cancer.

Methods

The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets are used as the training and test sets. Classified according to cancer and paracancerous tissues, we identified differentially expressed cancer driver genes. We further screened prognosis-associated genes, and candidate genes were submitted for the construction of a risk signature. Functional enrichment analysis and transcriptional regulatory networks were performed to search for possible mechanisms by which cancer driver genes affect breast cancer prognosis.

Results

We identified more than 200 differentially expressed driver genes and 27 prognosis-related genes. High-risk group patients had a lower survival rate compared to the low-risk group (P<0.05), and risk signature showed high specificity and sensitivity in predicting the patient prognosis (AUC 0.790). Multivariate regression analysis suggested that risk scores can independently predict patient prognosis. Further, we found differences in PD-1 expression, immune score, and stromal score among different risk groups.

Conclusion

Our study confirms the critical prognosis role of cancer driver genes in breast cancer. The cancer driver gene risk signature may provide a novel biomarker for clinical treatment strategy and survival prediction of breast cancer.

Lifting the innate immune barriers to antitumor immunity

The immune system evolved for adequate surveillance and killing of pathogens while minimizing host damage, such as due to chronic or exaggerated inflammation and autoimmunity. This is achieved by negative regulators and checkpoints that limit the magnitude and time course of the immune response. Tumor cells often escape immune surveillance and killing. Therefore, disrupting the brakes built into the immune system should effectively boost the anticancer immune response. The success of anti-CTLA4, anti-PD-1 and anti-PD-L1 have firmly established this proof of concept. Since the response rate of anti-CTLA4, anti-PD-1 and anti-PD-L1 is still limited, there is an intense effort for the identification of new targets and development of approaches that can expand the benefits of immunotherapy to a larger patient pool. Additional T cell checkpoints are obvious targets; however, here we focus on the unusual suspects—cells that function to initiate and guide T cell activity. Innate immunity is both an obligate prerequisite for the initiation of adaptive immune responses and a requirement for the recruitment of activated T cells to the site of action. We discuss some of the molecules present in innate immune cells, including natural killer cells, dendritic cells, macrophages, myeloid-derived suppressor cells, endothelial cells and stromal cells, that can activate or enhance innate immune cell functions, and more importantly, the inhibitors or checkpoints present in these cells that restrain their functions. Boosting innate immunity, either by enhancing activator functions or, preferably, by blocking the inhibitors, may represent a new anticancer treatment modality or at least function as adjuvants to T cell checkpoint inhibitors.

Tertiary Lymphoid Structure-B Cells Narrow Regulatory T Cells Impact in Lung Cancer Patients

The presence of tertiary lymphoid structures (TLS) in the tumor microenvironment is associated with better clinical outcome in many cancers. In non-small cell lung cancer (NSCLC), we have previously showed that a high density of B cells within TLS (TLS-B cells) is positively correlated with tumor antigen-specific antibody responses and increased intratumor CD4⁺ T cell clonality. Here, we investigated the relationship between the presence of TLS-B cells and CD4⁺ T cell profile in NSCLC patients. The expression of immune-related genes and proteins on B cells and CD4⁺ T cells was analyzed according to their relationship to TLS-B density in a prospective cohort of 56 NSCLC patients. We observed that tumor-infiltrating T cells showed marked differences according to TLS-B cell presence, with higher percentages of naïve, central-memory, and activated CD4⁺ T cells and lower percentages of both immune checkpoint (ICP)-expressing CD4⁺ T cells and regulatory T cells (Tregs) in the TLS-B^high tumors. A retrospective study of 538 untreated NSCLC patients showed that high TLS-B cell density was even able to counterbalance the deleterious impact of high Treg density on patient survival, and that TLS-B^high Treg^low patients had the best clinical outcomes. Overall, the correlation between the density of TLS-B^high tumors with early differentiated, activated and non-regulatory CD4⁺ T cell cells suggest that B cells may play a central role in determining protective T cell responses in NSCLC patients.

Harnessing immunity for therapy in human papillomavirus driven cancers

In persistent high-risk HPV infection, viral gene expression can trigger some important early changes to immune capabilities which act to protect the lesion from immune attack and subsequently promote its growth and ability for sustained immune escape. This includes immune checkpoint-inhibitor ligand expression (e.g. PD-L1) by tumour or associated immune cells that can block any anti-tumour T-cell effectors. While there are encouraging signs of efficacy for cancer immunotherapies including with immune checkpoint inhibitors, therapeutic vaccines and adoptive cell therapies, overall response and survival rates remain relatively low. HPV oncogene vaccination has shown some useful efficacy in treatment of patients with high-grade lesions but was unable to control later stage cancers. To maximally exploit anti-tumour immune responses, the suppressive factors associated with HPV carcinogenesis must be countered. Importantly, a combination of chemotherapy, reducing immunosuppressive myeloid cells, with therapeutic HPV vaccination significantly improves impact on cancer treatment. Many clinical trials are investigating checkpoint inhibitor treatments in HPV associated cancers but response rates are limited; combination with vaccination is being tested. Further investigation of how chemo- and/or radio-therapy can influence the recovery of effective anti-tumour immunity is warranted. Understanding how to optimally deploy and sequence conventional and immunotherapies is the challenge.

Targeted Delivery of CXCL9 and OX40L by Mesenchymal Stem Cells Elicits Potent Antitumor Immunity

Major obstacles in immunotherapies include toxicities associated with systemic administration of therapeutic agents, as well as low tumor lymphocyte infiltration that hampers the efficacies. In this study, we report a mesenchymal stem cell (MSC)-based immunotherapeutic strategy in which MSCs specifically deliver T/natural killer (NK) cell-targeting chemokine CXCL9 and immunostimulatory factor OX40 ligand (OX40L)/tumor necrosis factor superfamily member 4 (TNFSF4) to tumor sites in syngeneic subcutaneous and azoxymethane (AOM)/dextran sulfate sodium (DSS)-induced spontaneous colon cancer mouse models. This approach generated potent local antitumor immunity by increasing the ratios of tumor-infiltrating CD8⁺ T and NK cells and production of antitumor cytokines and cytolytic proteins in the tumor microenvironment. Moreover, it improved the efficacy of programmed death-1 (PD-1) blockade in a syngeneic mouse model and significantly suppressed the growth of major histocompatibility complex class I (MHC class I)-deficient tumors. Our MSC-based immunotherapeutic strategy simultaneously recruits and activates immune effector cells at the tumor site, thus overcoming the problems with toxicities of systemic therapeutic agents and low lymphocyte infiltration of solid tumors.

Immunotherapies in ovarian cancer

Ovarian cancer is the leading cause of death for gynaecological cancer, and new therapies are urgently awaited. Although the presence of tumour-infiltrating lymphocytes has been confirmed to be associated to a better prognosis, immunotherapy is not yet incorporated to the armamentarium in ovarian cancer. This review briefly summarises the strategies that have been tested or are under study for the three different groups of tumours: immune desert, inflamed and immune-excluded ovarian tumours. Finally, a better knowledge of the biology and immune microenvironment is needed for successfully developing new immunotherapy strategies.

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Immune ovarian cancer subtypes could improve the selection patients for immunotherapy.

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Very frequently ovarian cancer needs to be converted in an inflamed tumour.

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Checkpoints inhibitor combinations are well designed and very promising in ovarian cancer.

How to use macrophages to realise the treatment of tumour

Macrophages (Mø) are immune cells with natural phagocytic ability and play an important role in tumorigenesis, development and metastasis. Mø play a dual role of tumour inhibition and tumour promotion in tumour development due to their two different phenotypes. Mø in the tumour microenvironment have long been referred to as tumour-associated Mø (TAMs). Mø are mainly involved in tumour resistance, cancer metastasis and mediating immunosuppression. Nowadays, Mø and Mø membranes have been widely used in drug delivery systems (DDSs) because of their good biocompatibility, natural phagocytosis and their important role in tumour development. In this review, from the perspective of Mø's role in tumour development, we present strategies and drugs of Mø targeting and focusing on the several types of biomimetic nanoparticles constructed by Mø and Mø membranes in tumour therapy, and discuss the problem of this delivery system in present research and future directions.

CD137/OX40 Bispecific Antibody Induces Potent Antitumor Activity that Is Dependent on Target Coengagement

Following the success of immune checkpoint blockade therapy against cancer, agonistic antibodies targeting T-cell costimulatory pathways are in clinical trials. The TNF superfamily of receptors (TNFRSF) members CD137 and OX40 are costimulatory receptors that stimulate T-cell proliferation and activation upon interaction with their cognate ligands. Activating CD137 and OX40 with agonistic mAbs stimulates the immune system due to their broad expression on CD4⁺ and CD8⁺ T cells and natural killer cells and has antitumor effects in preclinical models. Most TNFRSF agonist antibodies require crosslinking via Fcγ receptors (FcγR), which can limit their clinical activity. FS120 mAb², a dual agonist bispecific antibody targeting CD137 and OX40, activated both CD4⁺ and CD8⁺ T cells in an FcγR-independent mechanism, dependent on concurrent binding. A mouse surrogate version of the bispecific antibody displayed antitumor activity in syngeneic tumor models, independent of T regulatory cell depletion and of FcγR interaction, but associated with peripheral T-cell activation and proliferation. When compared with a crosslink-independent CD137 agonist mAb, the FS120 surrogate induced lower liver T-cell infiltration. These data support initiation of clinical development of FS120, a first-in-class dual agonist bispecific antibody for the treatment of human cancer.

Co-Stimulatory Receptors in Cancers and Their Implications for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs), including anti-PD-1 and anti-CTLA-4 therapeutic agents, are now approved by the Food and Drug Administration for treatment of various types of cancer. However, the therapeutic efficacy of ICIs varies among patients and cancer types. Moreover, most patients do not develop durable antitumor responses after ICI therapy due to an ephemeral reversal of T-cell dysfunction. As co-stimulatory receptors play key roles in regulating the effector functions of T cells, activating co-stimulatory pathways may improve checkpoint inhibition efficacy, and lead to durable antitumor responses. Here, we review recent advances in our understating of co-stimulatory receptors in cancers, providing the necessary groundwork for the rational design of cancer immunotherapy.

Reduction of immunosuppressive tumor microenvironment in cholangiocarcinoma by ex vivo targeting immune checkpoint molecules

BACKGROUND & AIMS

Cholangiocarcinoma is an aggressive hepatobiliary malignancy originating from biliary tract epithelium. Whether cholangiocarcinoma is responsive to immune checkpoint antibody therapy is unknown, and knowledge of its tumor immune microenvironment is limited. We aimed to characterize tumor-infiltrating lymphocytes (TILs) in cholangiocarcinoma and assess functional effects of targeting checkpoint molecules on TILs.

METHODS

We isolated TILs from resected tumors of patients with cholangiocarcinoma and investigated their compositions compared with their counterparts in tumor-free liver (TFL) tissues and blood, by flow cytometry and immunohistochemistry. We measured expression of immune co-stimulatory and co-inhibitory molecules on TILs, and determined whether targeting these molecules improved ex vivo functions of TILs.

RESULTS

Proportions of cytotoxic T cells and natural killer cells were decreased, whereas regulatory T cells were increased in tumors compared with TFL. While regulatory T cells accumulated in tumors, the majority of cytotoxic and helper T cells were sequestered at tumor margins, and natural killer cells were excluded from the tumors. The co-stimulatory receptor GITR and co-inhibitory receptors PD1 and CTLA4 were over-expressed on tumor-infiltrating T cells compared with T cells in TFL and blood. Antagonistic targeting of PD1 or CTLA4 or agonistic targeting of GITR enhanced effector molecule production and T cell proliferation in ex vivo stimulation of TILs derived from cholangiocarcinoma. The inter-individual variations in TIL responses to checkpoint treatments were correlated with differences in TIL immune phenotype.

CONCLUSIONS

Decreased numbers of cytotoxic immune cells and increased numbers of suppressor T cells that over-express co-inhibitory receptors suggest that the tumor microenvironment in cholangiocarcinoma is immunosuppressive. Targeting GITR, PD1 or CTLA4 enhances effector functions of tumor-infiltrating T cells, indicating that these molecules are potential immunotherapeutic targets for patients with cholangiocarcinoma.

LAY SUMMARY

The defense functions of immune cells are suppressed in cholangiocarcinoma tumors. Stimulating or blocking "immune checkpoint" molecules expressed on tumor-infiltrating T cells can enhance the defense functions of these cells. Therefore, these molecules may be promising targets for therapeutic stimulation of immune cells to eradicate the tumors and prevent cancer recurrence in patients with cholangiocarcinoma.

A synergistic triad of chemotherapy, immune checkpoint inhibitors, and caloric restriction mimetics eradicates tumors in mice

We have recently shown that chemotherapy with immunogenic cell death (ICD)-inducing agents can be advantageously combined with fasting regimens or caloric restriction mimetics (CRMs) to achieve superior tumor growth control via a T cell-dependent mechanism. Here, we show that the blockade of the CD11b-dependent extravasation of myeloid cells blocks such a combination effect as well. Based on the characterization of the myeloid and lymphoid immune infiltrates, including the expression pattern of immune checkpoint proteins (and noting a chemotherapy-induced overexpression of programmed death-ligand 1, PD-L1, on both cancer cells and leukocytes, as well as a reduced frequency of exhausted CD8+ T cells positive for programmed cell death 1 protein, PD-1), we then evaluated the possibility to combine ICD inducers, CRMs and targeting of the PD-1/PD-L1 interaction. While fasting or CRMs failed to improve tumor growth control by PD-1 blockade, ICD inducers alone achieved a partial sensitization to treatment with a PD-1-specific antibody. However, definitive cure of most of the tumor-bearing mice was only achieved by a tritherapy combining (i) ICD inducers exemplified by mitoxantrone and oxaliplatin, (ii) CRMs exemplified by hydroxycitrate and spermidine and substitutable for by fasting, and (iii) immune checkpoint inhibitors (ICIs) targeting the PD-1/PD-L1 interaction. Altogether, these results point to the possibility of synergistic interactions among distinct classes of anticancer agents.

Recombinant Adenovirus Expressing a Soluble Fusion Protein PD-1/CD137L Subverts the Suppression of CD8+ T Cells in HCC

Oncolytic viruses are an excellent platform for developing effective strategies in cancer immunotherapy. Several challenges remain in the use of viro-immunotherapy for cancer, such as the lack of costimulatory signals and negative regulation of immune checkpoints. In this study, we designed a novel adenovirus expressing a soluble fusion protein, programmed cell death protein 1 (PD-1)/CD137L, which contains the extracellular domains of PD-1 and CD137L at each terminus (Ad5-PC). Ad5-PC preserved the costimulatory activity of CD137L and facilitated the persistence of activated CD8⁺ T cells. Ad5-PC induced strikingly increased antitumor activity in both ascitic and subcutaneous hepatocellular carcinoma (HCC) tumor models, with 70% and 60% long-term cure rates, respectively. The improved antitumor effect of Ad5-PC was attributed to the sustained high-level lymphocyte activation and interferon (IFN)-γ production in the tumor microenvironment, and was essentially dependent on CD8⁺ T cells rather than natural killer (NK) cells. Moreover, Ad5-huPC-expressing human soluble PD-1/CD137L fusion protein was effective in suppressing tumor growth and improving survival in a humanized mouse model. We confirmed that Ad5-PC induced tumor-specific and systematic protection against tumor rechallenges at both in situ and distant sites. Thus, Ad5-PC harnesses several distinct functions to efficiently overcome several major hurdles of viro-immunotherapy.

Carcinoembryonic Antigen (CEA)-Specific 4-1BB-Costimulation Induced by CEA-Targeted 4-1BB-Agonistic Trimerbodies

4-1BB (CD137) is an inducible costimulatory receptor that promotes expansion and survival of activated T cells; and IgG-based 4-1BB-agonistic monoclonal antibodies exhibited potent antitumor activity in clinical trials. However, the clinical development of those antibodies is restricted by major off-tumor toxicities associated with FcγR interactions. We have recently generated an EGFR-targeted 4-1BB-agonistic trimerbody that demonstrated strong antitumor activity and did not induce systemic inflammatory cytokine secretion and hepatotoxicity associated with first-generation 4-1BB agonists. Here, we generate a bispecific 4-1BB-agonistic trimerbody targeting the carcinoembryonic antigen (CEA) that is highly expressed in cancers of diverse origins. The CEA-targeted anti-4-1BB-agonistic trimerbody consists of three 4-1BB-specific single-chain fragment variable antibodies and three anti-CEA single-domain antibodies positioned around a murine collagen XVIII-derived homotrimerization domain. The trimerbody was produced as a homogenous, non-aggregating, soluble protein purifiable by standard affinity chromatographic methods. The purified trimerbody was found to be trimeric in solution, very efficient at recognizing 4-1BB and CEA, and potently costimulating T cells in vitro in the presence of CEA. Therefore, trimerbody-based tumor-targeted 4-1BB costimulation is a broadly applicable and clinically feasible approach to enhance the costimulatory environment of disseminated tumor lesions.

The Evolving Role of CD8+CD28- Immunosenescent T Cells in Cancer Immunology

Functional, tumor-specific CD8⁺ cytotoxic T lymphocytes drive the adaptive immune response to cancer. Thus, induction of their activity is the ultimate aim of all immunotherapies. Success of anti-tumor immunotherapy is precluded by marked immunosuppression in the tumor microenvironment (TME) leading to CD8⁺ effector T cell dysfunction. Among the many facets of CD8⁺ T cell dysfunction that have been recognized—tolerance, anergy, exhaustion, and senescence—CD8⁺ T cell senescence is incompletely understood. Naïve CD8⁺ T cells require three essential signals for activation, differentiation, and survival through T-cell receptor, costimulatory receptors, and cytokine receptors. Downregulation of costimulatory molecule CD28 is a hallmark of senescent T cells and increased CD8⁺CD28⁻ senescent populations with heterogeneous roles have been observed in multiple solid and hematogenous tumors. T cell senescence can be induced by several factors including aging, telomere damage, tumor-associated stress, and regulatory T (Treg) cells. Tumor-induced T cell senescence is yet another mechanism that enables tumor cell resistance to immunotherapy. In this paper, we provide a comprehensive overview of CD8⁺CD28⁻ senescent T cell population, their origin, their function in immunology and pathologic conditions, including TME and their implication for immunotherapy. Further characterization and investigation into this subset of CD8⁺ T cells could improve the efficacy of future anti-tumor immunotherapy.

GITRL-armed Delta-24-RGD oncolytic adenovirus prolongs survival and induces anti-glioma immune memory

Background

Viroimmunotherapy is evolving as a strong alternative for the standard treatment of malignant gliomas. Promising results from a recent clinical trial testing the anticancer effect of Delta-24-RGD in patients with glioblastoma suggested the induction of antitumoral immunity after viral administration. To further enhance the anti-glioma immune effect, we have armed Delta-24-RGD with the costimulatory ligand GITRL (Delta-24-GREAT [Glucocorticoid Receptor Enhanced Activity of T cells]).

Methods

We tested the infectivity and replication of Delta-24-GREAT, and the expression of ectopic GITRL in human and murine glioma cell lines. In vivo experiments involved the intracranial implantation of glioma cells into an immunocompetent model to study the anticancer effect, and rechallenging experiments to study long-term protection. Phenotypic and functional characterization of lymphocyte populations were performed by FACS and ELISA for Th1 cytokines expression, respectively.

Results

Our results showed that Delta-24-GREAT infects and induces the expression of GITRL. Delta-24-GREAT prolonged the survival of glioma-bearing immunocompetent mice and resulted in both anti-viral and anti-glioma immune responses, including increased frequency of central memory CD8⁺ T cells. Rechallenging the surviving mice with a second implantation of glioma cells did not lead to tumor growth; however, the surviving mice developed lethal tumors when B16/F10 melanoma cells were implanted intracranially, strongly indicating that the immune response was specific for glioma antigens.

Conclusions

GITRL-armed Delta-24-RGD treatment results in an antigen-restricted antitumor memory, an enhanced anti-glioma effect, and the generation of central immune memory. Our results strongly indicate that this strategy represents a vertical advance in virotherapy designed to treat patients with malignant brain tumors.

Immunogenicity of immunomodulatory, antibody-based, oncology therapeutics

The increasing use of multiple immunomodulatory (IMD) agents for cancer therapies (e.g. antibodies targeting immune checkpoints, bispecific antibodies, and chimeric antigen receptor [CAR]-T cells), is raising questions on their potential immunogenicity and effects on treatment. In this review, we outline the mechanisms of action (MOA) of approved, antibody-based IMD agents, potentially related to their immunogenicity, and discuss the reported incidence of anti-drug antibodies (ADA) as well as their clinical relevance in patients with cancer. In addition, we discuss the impact of the administration route and potential strategies to reduce the incidence of ADA and manage treated patients. Analysis of published reports indicated that the risk of immunogenicity did not appear to correlate with the MOA of anti-programmed death 1 (PD-1)/PD-ligand 1 monoclonal antibodies nor to substantially affect treatment with most of these agents in the majority of patients evaluated to date. Treatment with B-cell depleting agents appears associated with a low risk of immunogenicity. No significant difference in ADA incidence was found between the intravenous and subcutaneous administration routes for a panel of non-oncology IMD antibodies. Additionally, while the data suggest a higher likelihood of immunogenicity for antibodies with T-cell or antigen-presenting cell (APC) targets versus B-cell targets, it is possible to have targets expressed on APCs or T cells and still have a low incidence of immunogenicity.

GITR ligation enhances functionality of tumor-infiltrating T cells in hepatocellular carcinoma

No curative treatment options are available for advanced hepatocellular carcinoma (HCC). Anti-PD1 antibody therapy can induce tumor regression in 20% of advanced HCC patients, demonstrating that co-inhibitory immune checkpoint blockade has therapeutic potential for this type of cancer. However, whether agonistic targeting of co-stimulatory receptors might be able to stimulate anti-tumor immunity in HCC is as yet unknown. We investigated whether agonistic targeting of the co-stimulatory receptor GITR could reinvigorate ex vivo functional responses of tumor-infiltrating lymphocytes (TIL) freshly isolated from resected tumors of HCC patients. In addition, we compared GITR expression between TIL and paired samples of leukocytes isolated from blood and tumor-free liver tissues, and studied the effects of combined GITR and PD1 targeting on ex vivo TIL responses. In all three tissue compartments, CD4⁺ FoxP3⁺ regulatory T cells (Treg) showed higher GITR^- expression than effector T-cell subsets. The highest expression of GITR was found on CD4⁺ FoxP3^hi CD45RA^- activated Treg in tumors. Recombinant GITR-ligand as well as a humanized agonistic anti-GITR antibody enhanced ex vivo proliferative responses of CD4⁺ and CD8⁺ TIL to tumor antigens presented by mRNA-transfected autologous B-cell blasts, and also reinforced proliferation, IFN-γ secretion and granzyme B production in stimulations of TIL with CD3/CD28 antibodies. Combining GITR ligation with anti-PD1 antibody nivolumab further enhanced tumor antigen-specific responses of TIL in some, but not all, HCC patients, compared to either single treatment. In conclusion, agonistic targeting of GITR can enhance functionality of HCC TIL, and may therefore be a promising strategy for single or combinatorial immunotherapy in HCC.

Mutational and Antigenic Landscape in Tumor Progression and Cancer Immunotherapy

Evolving neoplasms accumulate non-synonymous mutations at a high rate, potentially enabling the expression of antigenic epitopes that can be recognized by the immune system. Since they are not covered by central tolerance, such tumor neoantigens (TNAs) should be under robust immune control as they surge. However, genetic defects that impair cancer cell eradication by the immune system coupled with the establishment of local immunosuppression can enable TNA accumulation, which is generally associated with improved clinical sensitivity to various immunotherapies. Here, we explore how tumor-intrinsic factors and immunological processes shape the mutational and antigenic landscape of evolving neoplasms to influence clinical responses to immunotherapy, and propose strategies to achieve robust immunological control of the disease despite disabled immunosurveillance.

Nouvelles perspectives dans l’immunothérapie des cancers pédiatriques

NEW PERSPECTIVES IN IMMUNOTHERAPIES FOR PEDIATRIC MALIGNANCIES

New therapeutic paradigms are needed to improve the survival of children and adolescents with high-risk malignancies, and to reduce the sequelae associated with treatment. Immunotherapies, targeting tumor cells and/or the immune system to enhance existing anti-tumor immunity or induce novel anti-tumor immune responses, are becoming increasingly successful in adult oncology. Based on the results obtained with anti-ganglioside2 antibodies in neuroblastoma, rituximab in mature B malignancies, immune checkpoint inhibitors in lymphoma and especially in Hodgkin lymphoma, blinatumomab and CAR-T CD19 cells for B-cell acute lymphoblastic leukemia, immunotherapy has demonstrated irrefutable benefits in pediatric patients. However, these results are currently limited to a minority of patients and histologies. Current and ongoing trials tend to focus on a single type of immunotherapy, but it is likely that combinations of immunotherapies with different mechanisms of action or combination with other classes of anti-cancer treatments will be additives or even synergistic. The development of this new class of drugs in the treatment of pediatric cancers has multiple challenges: to better evaluate the response to treatment, to define the optimal doses and schedules, to manage immuno-mediated toxicities, to identify its specific sequelae, and, finally, to better understand the strategies of immune evasion of pediatric cancers in order to develop efficient immunotherapies.

RNA-seq for identification of therapeutically targetable determinants of immune activation in human glioblastoma

INTRODUCTION

We sought to determine which therapeutically targetable immune checkpoints, costimulatory signals, and other tumor microenvironment (TME) factors are independently associated with immune cytolytic activity (CYT), a gene expression signature of activated effector T cells, in human glioblastoma (GBM).

METHODS

GlioVis was accessed for RNA-seq data from The Cancer Genome Atlas (TCGA). For subjects with treatment-naïve, primary GBM, we quantified mRNA expression of 28 therapeutically targetable TME factors. CYT (geometric mean of GZMA and PRF1 expression) was calculated for each tumor. Multiple linear regression was performed to determine the relationship between the dependent variable (CYT) and mRNA expression of each of the 28 factors. Variables associated with CYT in multivariate analysis were subsequently evaluated for this association in an independent cohort of newly diagnosed GBMs from the Chinese Glioma Cooperative Group (CGCG).

RESULTS

109 TCGA tumors were analyzed. The final multiple linear regression model included the following variables, each positively associated with CYT except VEGF-A (negative association): CSF-1 (p = 0.003), CD137 (p = 0.042), VEGF-A (p < 0.001), CTLA4 (p = 0.028), CD40 (p = 0.023), GITR (p = 0.020), IL6 (p = 0.02), and OX40 (p < 0.001). In CGCG (n = 52), each of these variables remained significantly associated with CYT in univariate analysis except for VEGF-A. In multivariate analysis, only CTLA4 and CD40 remained statistically significant.

CONCLUSIONS

Using multivariate modeling of RNA-seq gene expression data, we identified therapeutically targetable TME factors that are independently associated with intratumoral cytolytic T-cell activity in human GBM. As a myriad of systemic immunotherapies are now available for investigation, our results could inform rational combinations for evaluation in GBM.

Trial watch: Peptide-based vaccines in anticancer therapy

Peptide-based anticancer vaccination aims at stimulating an immune response against one or multiple tumor-associated antigens (TAAs) following immunization with purified, recombinant or synthetically engineered epitopes. Despite high expectations, the peptide-based vaccines that have been explored in the clinic so far had limited therapeutic activity, largely due to cancer cell-intrinsic alterations that minimize antigenicity and/or changes in the tumor microenvironment that foster immunosuppression. Several strategies have been developed to overcome such limitations, including the use of immunostimulatory adjuvants, the co-treatment with cytotoxic anticancer therapies that enable the coordinated release of damage-associated molecular patterns, and the concomitant blockade of immune checkpoints. Personalized peptide-based vaccines are also being explored for therapeutic activity in the clinic. Here, we review recent preclinical and clinical progress in the use of peptide-based vaccines as anticancer therapeutics.Abbreviations: CMP: carbohydrate-mimetic peptide; CMV: cytomegalovirus; DC: dendritic cell; FDA: Food and Drug Administration; HPV: human papillomavirus; MDS: myelodysplastic syndrome; MHP: melanoma helper vaccine; NSCLC: non-small cell lung carcinoma; ODD: orphan drug designation; PPV: personalized peptide vaccination; SLP: synthetic long peptide; TAA: tumor-associated antigen; TNA: tumor neoantigen

Stimulating T Cells Against Cancer With Agonist Immunostimulatory Monoclonal Antibodies

Elimination of cancer cells through antitumor immunity has been a long-sought after goal since Sir F. Macfarlane Burnet postulated the theory of immune surveillance against tumors in the 1950s. Finally, the use of immunotherapeutics against established cancer is becoming a reality in the past 5years. Most notable are the monoclonal antibodies (mAbs) directed against inhibitory T-cell receptors cytotoxic T lymphocyte antigen-4 and programmed death-1. The next generation of mAbs targeting T cells is designed to stimulate costimulatory receptors on T cells. Here we review the recent progress on these immunostimulatory agonist antibodies against the costimulatory receptors CD137, GITR, OX40, and CD27.

Breast Cancer Immunotherapy: An Update

The immune system plays a major role in cancer surveillance. Harnessing its power to treat many cancers is now a reality that has led to cures in hopeless situations where no other solutions were available from traditional anticancer drugs. These spectacular achievements rekindled the oncology community's interest in extending the benefits to all cancers including breast cancer. The first section of this article reviews the biological foundations of the immune response to different subtypes of breast cancer and the ways cancer may overcome the immune attack leading to cancer disease. The second section is dedicated to the actual immune treatments including breast cancer vaccines, checkpoint inhibitors, monoclonal antibodies, and the "unconventional" immune role of chemotherapy.

Combination Immunotherapy: Taking Cancer Vaccines to the Next Level

With the advent of checkpoint blockade therapies, immunotherapy is now a critical modality for the treatment of some cancers. While some patients respond well to checkpoint blockade, many do not, necessitating the need for other forms of therapy. Vaccination against malignancy has been a long sought goal of science. For cancers holding a microbial etiology, vaccination has been highly effective in reducing the incidence of disease. However, vaccination against established malignancy has been largely disappointing. In this review, we discuss efforts to develop diverse vaccine modalities in the treatment of cancer with a particular focus on melanoma. Recent work has suggested that vaccines targeting patient-specific tumor mutations may be more relevant than those targeting unmutated proteins. Nonetheless, tumor cells utilize many strategies to evade host immunity. It is likely that the full potential of cancer vaccination will only be realized when vaccines are combined with other therapies targeting tumor immunoevasive mechanisms. By modulating inhibitory molecules, regulatory immune cells, and the metabolic resources and demands of T cells, scientists and clinicians can ensure vaccine-stimulated T cells are fully functional within the immunosuppressive tumor microevironment.

Next generation of immune checkpoint therapy in cancer: new developments and challenges

Immune checkpoints consist of inhibitory and stimulatory pathways that maintain self-tolerance and assist with immune response. In cancer, immune checkpoint pathways are often activated to inhibit the nascent anti-tumor immune response. Immune checkpoint therapies act by blocking or stimulating these pathways and enhance the body's immunological activity against tumors. Cytotoxic T lymphocyte-associated molecule-4 (CTLA-4), programmed cell death receptor-1 (PD-1), and programmed cell death ligand-1(PD-L1) are the most widely studied and recognized inhibitory checkpoint pathways. Drugs blocking these pathways are currently utilized for a wide variety of malignancies and have demonstrated durable clinical activities in a subset of cancer patients. This approach is rapidly extending beyond CTLA-4 and PD-1/PD-L1. New inhibitory pathways are under investigation, and drugs blocking LAG-3, TIM-3, TIGIT, VISTA, or B7/H3 are being investigated. Furthermore, agonists of stimulatory checkpoint pathways such as OX40, ICOS, GITR, 4-1BB, CD40, or molecules targeting tumor microenvironment components like IDO or TLR are under investigation. In this article, we have provided a comprehensive review of immune checkpoint pathways involved in cancer immunotherapy, and discuss their mechanisms and the therapeutic interventions currently under investigation in phase I/II clinical trials. We also reviewed the limitations, toxicities, and challenges and outline the possible future research directions.

Trial Watch: Immunostimulation with recombinant cytokines for cancer therapy

Cytokines regulate virtually aspects of innate and adaptive immunity, including the initiation, execution and extinction of tumor-targeting immune responses. Over the past three decades, the possibility of using recombinant cytokines as a means to elicit or boost clinically relevant anticancer immune responses has attracted considerable attention. However, only three cytokines have been approved so far by the US Food and Drug Administration and the European Medicines Agency for use in cancer patients, namely, recombinant interleukin (IL)-2 and two variants of recombinant interferon alpha 2 (IFN-α2a and IFN-α2b). Moreover, the use of these cytokines in the clinics is steadily decreasing, mostly as a consequence of: (1) the elevated pleiotropism of IL-2, IFN-α2a and IFN-α2b, resulting in multiple unwarranted effects; and (2) the development of highly effective immunostimulatory therapeutics, such as immune checkpoint blockers. Despite this and other obstacles, research in the field continues as alternative cytokines with restricted effects on specific cell populations are being evaluated. Here, we summarize research preclinical and clinical developments on the use of recombinant cytokines for immunostimulation in cancer patients.