CD27-Mediated Regulatory T Cell Depletion and Effector T Cell Costimulation Both Contribute to Antitumor Efficacy

Interferon signaling and ferroptosis in tumor immunology and therapy

This study sought to elucidate the mechanisms underlying the impact of the interferon signaling pathway on Ferroptosis in tumor cells and its correlation with CD8 + T cell exhaustion. Using mouse models and single-cell sequencing, the researchers studied the interaction between CD8 + T cells and the interferon signaling pathway. Differential gene analysis revealed key genes involved in CD8 + T cell exhaustion, and their downstream factors were explored using bioinformatics tools. The expression levels of interferon-related genes associated with Ferroptosis were analyzed using data from the TCGA database, and their relevance to tumor tissue Ferroptosis and patients' prognosis was determined. In vitro experiments were conducted to measure the levels of IFN-γ, MDA, and LPO, as well as tumor cell viability and apoptosis. In vivo validation using a mouse tumor model confirmed the results obtained from the in vitro experiments, highlighting the potential of silencing HSPA6 or DNAJB1 in enhancing the efficacy of PD-1 therapy and inhibiting tumor growth and migration.

A Phase I Trial of Atezolizumab and Varlilumab in Combination With Radiation in Patients With Metastatic NSCLC

Introduction

Anti-programmed cell death 1 (PD-1) immunotherapy is the standard of care for metastatic NSCLC but many tumors develop resistance. We hypothesized that combining a T-cell agonist such as varlilumab (anti-CD27 antibody) with checkpoint inhibition may be synergistic and this synergy may be potentiated further by using targeted radiation (RT).

Methods

We conducted an open-label, single-center, phase I trial (NCT04081688) to determine the safety and clinical benefit of the atezolizumab and varlilumab in combination with palliative RT in patients with advanced or metastatic NSCLC with progression on prior programmed cell death ligand 1therapy. On day 1 of each 21-day cycle, patients received varlilumab followed by atezolizumab on day 2. RT to a lung lesion was administered between cycle 1 and cycle 2.

Results

A total of 15 patients were enrolled (one patient did not start treatment). The median age was 64 years; 10 patients were female. Eight patients (57%) had at least one treatment-related adverse event (AE) and 7 (50%) had at least one grade III or worse treatment-related AE. There was only one grade III immune-related AE requiring steroids (1 diarrhea and colitis); there were no treatment-related deaths. Of the 12 patients evaluable for efficacy, three patients had stable disease (2 with stable disease > 4 mo) and the clinical benefit rate was 25%. The median progression-free survival was two months and the median overall survival was 6.4 months.

Conclusions

Varlilumab in combination with atezolizumab and RT was safe and well tolerated; no additional signal was identified for toxicity. Clinical activity for the combination was modest with 25% of patients with stable disease as the best response.

Impact of isotype on the mechanism of action of agonist anti-OX40 antibodies in cancer: implications for therapeutic combinations

BACKGROUND

OX40 has been widely studied as a target for immunotherapy with agonist antibodies taken forward into clinical trials for cancer where they are yet to show substantial efficacy. Here, we investigated potential mechanisms of action of anti-mouse (m) OX40 and anti-human (h) OX40 antibodies, including a clinically relevant monoclonal antibody (mAb) (GSK3174998) and evaluated how isotype can alter those mechanisms with the aim to develop improved antibodies for use in rational combination treatments for cancer.

METHODS

Anti-mOX40 and anti-hOX40 mAbs were evaluated in a number of in vivo models, including an OT-I adoptive transfer immunization model in hOX40 knock-in (KI) mice and syngeneic tumor models. The impact of FcγR engagement was evaluated in hOX40 KI mice deficient for Fc gamma receptors (FcγR). Additionally, combination studies using anti-mouse programmed cell death protein-1 (mPD-1) were assessed. In vitro experiments using peripheral blood mononuclear cells (PBMCs) examining possible anti-hOX40 mAb mechanisms of action were also performed.

RESULTS

Isotype variants of the clinically relevant mAb GSK3174998 showed immunomodulatory effects that differed in mechanism; mIgG1 mediated direct T-cell agonism while mIgG2a acted indirectly, likely through depletion of regulatory T cells (Tregs) via activating FcγRs. In both the OT-I and EG.7-OVA models, hIgG1 was the most effective human isotype, capable of acting both directly and through Treg depletion. The anti-hOX40 hIgG1 synergized with anti-mPD-1 to improve therapeutic outcomes in the EG.7-OVA model. Finally, in vitro assays with human peripheral blood mononuclear cells (hPBMCs), anti-hOX40 hIgG1 also showed the potential for T-cell stimulation and Treg depletion.

CONCLUSIONS

These findings underline the importance of understanding the role of isotype in the mechanism of action of therapeutic mAbs. As an hIgG1, the anti-hOX40 mAb can elicit multiple mechanisms of action that could aid or hinder therapeutic outcomes, dependent on the microenvironment. This should be considered when designing potential combinatorial partners and their FcγR requirements to achieve maximal benefit and improvement of patient outcomes.

Engaging stimulatory immune checkpoint interactions in the tumour immune microenvironment of primary liver cancers - how to push the gas after having released the brake

Hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA) are the first and second most common primary liver cancer (PLC). For decades, systemic therapies consisting of tyrosine kinase inhibitors (TKIs) or chemotherapy have formed the cornerstone of treating advanced-stage HCC and CCA, respectively. More recently, immunotherapy using immune checkpoint inhibition (ICI) has shown anti-tumour reactivity in some patients. The combination regimen of anti-PD-L1 and anti-VEGF antibodies has been approved as new first-line treatment of advanced-stage HCC. Furthermore, gemcibatine plus cisplatin (GEMCIS) with an anti-PD-L1 antibody is awaiting global approval for the treatment of advanced-stage CCA. As effective anti-tumour reactivity using ICI is achieved in a minor subset of both HCC and CCA patients only, alternative immune strategies to sensitise the tumour microenvironment of PLC are waited for. Here we discuss immune checkpoint stimulation (ICS) as additional tool to enhance anti-tumour reactivity. Up-to-date information on the clinical application of ICS in onco-immunology is provided. This review provides a rationale of the application of next-generation ICS either alone or in combination regimen to potentially enhance anti-tumour reactivity in PLC patients.

Fcγ receptor binding is required for maximal immunostimulation by CD70-Fc

Introduction

T cell expressed CD27 provides costimulation upon binding to inducible membrane expressed trimeric CD70 and is required for protective CD8 T cell responses. CD27 agonists could therefore be used to bolster cellular vaccines and anti-tumour immune responses. To date, clinical development of CD27 agonists has focussed on anti-CD27 antibodies with little attention given to alternative approaches.

Methods

Here, we describe the generation and activity of soluble variants of CD70 that form either trimeric (t) or dimer-of-trimer proteins and conduct side-by-side comparisons with an agonist anti-CD27 antibody. To generate a dimer-of-trimer protein (dt), we fused three extracellular domains of CD70 to the Fc domain of mouse IgG1 in a 'string of beads' configuration (dtCD70-Fc).

Results

Whereas tCD70 failed to costimulate CD8 T cells, both dtCD70-Fc and an agonist anti-CD27 antibody were capable of enhancing T cell proliferation in vitro. Initial studies demonstrated that dtCD70-Fc was less efficacious than anti-CD27 in boosting a CD8 T cell vaccine response in vivo, concomitant with rapid clearance of dtCD70-Fc from the circulation. The accelerated plasma clearance of dtCD70-Fc was not due to the lack of neonatal Fc receptor binding but was dependent on the large population of oligomannose type glycosylation. Enzymatic treatment to reduce the oligomannose-type glycans in dtCD70-Fc improved its half-life and significantly enhanced its T cell stimulatory activity in vivo surpassing that of anti-CD27 antibody. We also show that whereas the ability of the anti-CD27 to boost a vaccine response was abolished in Fc gamma receptor (FcγR)-deficient mice, dtCD70-Fc remained active. By comparing the activity of dtCD70-Fc with a variant (dtCD70-Fc(D265A)) that lacks binding to FcγRs, we unexpectedly found that FcγR binding to dtCD70-Fc was required for maximal boosting of a CD8 T cell response in vivo. Interestingly, both dtCD70-Fc and dtCD70-Fc(D265A) were effective in prolonging the survival of mice harbouring BCL1 B cell lymphoma, demonstrating that a substantial part of the stimulatory activity of dtCD70-Fc in this setting is retained in the absence of FcγR interaction.

Discussion

These data reveal that TNFRSF ligands can be generated with a tunable activity profile and suggest that this class of immune agonists could have broad applications in immunotherapy.

Beyond Bruton's tyrosine kinase inhibitors in mantle cell lymphoma: bispecific antibodies, antibody-drug conjugates, CAR T-cells, and novel agents

Mantle cell lymphoma is a B cell non-Hodgkin lymphoma (NHL), representing 2-6% of all NHLs and characterized by overexpression of cyclin D1. The last decade has seen the development of many novel treatment approaches in MCL, most notably the class of Bruton's tyrosine kinase inhibitors (BTKi). BTKi has shown excellent outcomes for patients with relapsed or refractory MCL and is now being studied in the first-line setting. However, patients eventually progress on BTKi due to the development of resistance. Additionally, there is an alteration in the tumor microenvironment in these patients with varying biological and therapeutic implications. Hence, it is necessary to explore novel therapeutic strategies that can be effective in those who progressed on BTKi or potentially circumvent resistance. In this review, we provide a brief overview of BTKi, then discuss the various mechanisms of BTK resistance including the role of genetic alteration, cancer stem cells, tumor microenvironment, and adaptive reprogramming bypassing the effect of BTK inhibition, and then provide a comprehensive review of current and emerging therapeutic options beyond BTKi including novel agents, CAR T cells, bispecific antibodies, and antibody-drug conjugates.

Production and N-glycan engineering of Varlilumab in Nicotiana benthamiana

N-glycan engineering has dramatically evolved for the development and quality control of recombinant antibodies. Fc region of IgG contains two N-glycans whose galactose terminals on Fc-glycan have been shown to increase the stability of CH2 domain and improve effector functions. Nicotiana benthamiana has become one of the most attractive production systems for therapeutic antibodies. In this study, Varlilumab, a CD27-targeting monoclonal antibody, was transiently produced in fresh leaves of soil-grown and hydroponic-grown N. benthamiana, resulted in the yield of 174 and 618 µg/gram, respectively. However, the IgG produced in wild-type N. benthamiana lacked the terminal galactose residues in its N-glycan. Therefore, N-glycan engineering was applied to fine-tune recombinant antibodies produced in plant platforms. We further co-expressed IgG together with murine β1,4-galactosyltransferase (β1,4-GALT) to modify plant N-glycan with β1,4-linked Gal residue(s) and Arabidopsis thaliana β1,3-galactosylatransferase (β1,3-GALT) to improve galactosylation. The co-expression of IgG with each of GALTs successfully resulted in modification of N-glycan structures on the plant-produced IgG. Notably, IgG co-expressed with murine β1,4-GALT in soil-grown N. benthamiana had 42.5% of N-glycans variants having galactose (Gal) residues at the non-reducing terminus and 55.3% of that in hydroponic-grown N. benthamiana plants. Concomitantly, N-glycan profile analysis of IgG co-expressed with β1,3-GALT demonstrated that there was an increased efficiency of galactosylation and an enhancement in the formation of Lewis a structure in plant-derived antibodies. Taken together, our findings show that the first plant-derived Varlilumab was successfully produced with biantennary β1,4-galactosylated N-glycan structures.

Friend or Foe - Tc17 cell generation and current evidence for their importance in human disease

The term Tc17 cells refers to interleukin 17 (IL-17)-producing CD8+ T cells. While IL-17 is an important mediator of mucosal defense, it is also centrally involved in driving the inflammatory response in immune-mediated diseases, such as psoriasis, multiple sclerosis, and inflammatory bowel disease. In this review, we aim to gather the current knowledge on the phenotypic and transcriptional profile, the in vitro and in vivo generation of Tc17 cells, and the evidence pointing towards a relevant role of Tc17 cells in human diseases such as infectious diseases, cancer, and immune-mediated diseases.

NK Cell-Targeted Immunotherapies in Bladder Cancer: Beyond Checkpoint Inhibitors

BACKGROUND

For decades, immunotherapies have been integral for the treatment and management of bladder cancer, with immune checkpoint inhibitors (ICIs) transforming patient care in recent years. However, response rates are poor to T cell-targeted ICIs such as programmed cell death protein 1 (PD-1) and programmed cell death-ligand 1 (PD-L1) blocking antibodies, framing a critical need for complementary immunotherapies. Promising strategies involve harnessing the activation potential of natural killer (NK) cells. They quickly exert their antitumor activity via signaling through germline-encoded activating receptors and are rapidly sensitized to new tissue microenvironments via their regulation by polymorphic HLA class I, KIR and NKG2A receptors.

OBJECTIVE

In this review, we examined the roles of currently available NK-targeted antitumor treatment strategies such as engineered viral vectors, small-molecule IMiDs, NK agonist antibodies, interleukins, and chimeric antigen receptor (CAR) NK cells, and their potential for improving the efficacy of immunotherapy in the treatment of bladder cancer.

METHODS

Through review of current literature, we summarized our knowledge of NK cells in solid tumors and hematologic malignancies as their roles pertain to novel immunotherapies already being applied to the treatment of bladder cancer or that offer rationale for considering as potential novel immunotherapeutic strategies.

RESULTS

NK cells play a critical role in shaping the tumor microenvironment (TME) that can be exploited to improve T cell-targeted immunotherapies.

CONCLUSIONS

Emerging evidence suggests that NK cells are a prime target for improving antitumor functions in immunotherapies for the treatment of bladder cancer. Further research into profiling NK cells in settings of immunotherapies for bladder cancer could help identify patients who might maximally benefit from NK cell-targeted immunotherapies and the various approaches for exploiting their antitumor properties.

Beyond CTLA-4 and PD-1 Inhibition: Novel Immune Checkpoint Molecules for Melanoma Treatment

More than ten years after the approval of ipilimumab, immune checkpoint inhibitors (ICIs) against PD-1 and CTLA-4 have been established as the most effective treatment for locally advanced or metastatic melanoma, achieving durable responses either as monotherapies or in combinatorial regimens. However, a considerable proportion of patients do not respond or experience early relapse, due to multiple parameters that contribute to melanoma resistance. The expression of other immune checkpoints beyond the PD-1 and CTLA-4 molecules remains a major mechanism of immune evasion. The recent approval of anti-LAG-3 ICI, relatlimab, in combination with nivolumab for metastatic disease, has capitalized on the extensive research in the field and has highlighted the potential for further improvement of melanoma prognosis by synergistically blocking additional immune targets with new ICI-doublets, antibody-drug conjugates, or other novel modalities. Herein, we provide a comprehensive overview of presently published immune checkpoint molecules, including LAG-3, TIGIT, TIM-3, VISTA, IDO1/IDO2/TDO, CD27/CD70, CD39/73, HVEM/BTLA/CD160 and B7-H3. Beginning from their immunomodulatory properties as co-inhibitory or co-stimulatory receptors, we present all therapeutic modalities targeting these molecules that have been tested in melanoma treatment either in preclinical or clinical settings. Better understanding of the checkpoint-mediated crosstalk between melanoma and immune effector cells is essential for generating more effective strategies with augmented immune response.

Delivering co-stimulatory tumor necrosis factor receptor agonism for cancer immunotherapy: past, current and future perspectives

The tumor necrosis factor superfamily (TNFSF) and their receptors (TNFRSF) are important regulators of the immune system, mediating proliferation, survival, differentiation, and function of immune cells. As a result, their targeting for immunotherapy is attractive, although to date, under-exploited. In this review we discuss the importance of co-stimulatory members of the TNFRSF in optimal immune response generation, the rationale behind targeting these receptors for immunotherapy, the success of targeting them in pre-clinical studies and the challenges in translating this success into the clinic. The efficacy and limitations of the currently available agents are discussed alongside the development of next generation immunostimulatory agents designed to overcome current issues, and capitalize on this receptor class to deliver potent, durable and safe drugs for patients.

Exposure of Immunogenic Tumor Antigens in Surrendered Immunity and the Significance of Autologous Tumor Cell-Based Vaccination in Precision Medicine

The mechanisms by which immune systems identify and destroy tumors, known as immunosurveillance, have been discussed for decades. However, several factors that lead to tumor persistence and escape from the attack of immune cells in a normal immune system have been found. In the process known as immunoediting, tumors decrease their immunogenicity and evade immunosurveillance. Furthermore, tumors exploit factors such as regulatory T cells, myeloid-derived suppressive cells, and inhibitory cytokines that avoid cytotoxic T cell (CTL) recognition. Current immunotherapies targeting tumors and their surroundings have been proposed. One such immunotherapy is autologous cancer vaccines (ACVs), which are characterized by enriched tumor antigens that can escalate specific CTL responses. Unfortunately, ACVs usually fail to activate desirable therapeutic effects, and the low immunogenicity of ACVs still needs to be elucidated. This difficulty highlights the significance of immunogenic antigens in antitumor therapies. Previous studies have shown that defective host immunity triggers tumor development by reprogramming tumor antigenic expressions. This phenomenon sheds new light on ACVs and provides a potential cue to improve the effectiveness of ACVs. Furthermore, synergistically with the ACV treatment, combinational therapy, which can reverse the suppressive tumor microenvironments, has also been widely proposed. Thus, in this review, we focus on tumor immunogenicity sculpted by the immune systems and discuss the significance and application of restructuring tumor antigens in precision medicine.

Immune checkpoint inhibitors for unresectable or metastatic pleomorphic dermal sarcomas

Pleomorphic dermal sarcomas (PDS) are rare neoplasms of the skin that occur in UV-exposed sites in the elderly, but represent the most common cutaneous sarcomas. Although the majority of PDS can be surgically removed, local recurrences occur in up to 28%, usually occurring within the first two years after primary excision. Metastases are diagnosed in up to 20% of cases, mainly observed in the skin, lymph nodes and lungs, preferentially affecting patients with underlying hemato-oncologic diseases. Similar to other UV-induced tumors, PDS are inflammatory and immunogenic tumors (with a high number of CD4+/CD8+ tumor-infiltrating lymphocytes (TILs) and checkpoint molecule expression such as PD-L1, LAG-3, TIGIT) with a very high mutational burden. The most common genetic alterations include UV-induced TP53 loss of function mutations, followed by alterations in the CDKN2A/B gene. Rarely, targetable genetic alterations can be detected. Compelling experimental data and clinical reports about PD-1/PD-L1-blocking antibodies in patients with PDS suggest its use as first line treatment in unresectable or metastatic tumor stages. However, individual ("off-line") patient management should be discussed in an interdisciplinary tumor board based on molecular genetic testing, mutational burden, PD-L1 expression, and evidence of tumor-infiltrating lymphocytes in addition to comorbities of the individual patient.

Preclinical characterization and clinical translation of pharmacodynamic markers for MK-5890: a human CD27 activating antibody for cancer immunotherapy

Background

Immune checkpoint inhibitors (ICI) have radically changed cancer therapy, but most patients with cancer are unresponsive or relapse after treatment. MK-5890 is a CD27 agonist antibody intended to complement ICI therapy. CD27 is a member of the tumor necrosis factor receptor superfamily that plays a critical role in promoting responses of T cells, B cells and NK cells.

Methods

Anti-CD27 antibodies were generated and selected for agonist activity using NF-кB luciferase reporter assays. Antibodies were humanized and characterized for agonism using in vitro T-cell proliferation assays. The epitope recognized on CD27 by MK-5890 was established by X-ray crystallography. Anti-tumor activity was evaluated in a human CD27 knock-in mouse. Preclinical safety was tested in rhesus monkeys. Pharmacodynamic properties were examined in mouse, rhesus monkeys and a phase 1 dose escalation clinical study in patients with cancer.

Results

Humanized anti-CD27 antibody MK-5890 (hIgG1) was shown to bind human CD27 on the cell surface with sub-nanomolar potency and to partially block binding to its ligand, CD70. Crystallization studies revealed that MK-5890 binds to a unique epitope in the cysteine-rich domain 1 (CRD1). MK-5890 activated CD27 expressed on 293T NF-κB luciferase reporter cells and, conditional on CD3 stimulation, in purified CD8+ T cells without the requirement of crosslinking. Functional Fc-receptor interaction was required to activate CD8+ T cells in an ex vivo tumor explant system and to induce antitumor efficacy in syngeneic murine subcutaneous tumor models. MK-5890 had monotherapy efficacy in these models and enhanced efficacy of PD-1 blockade. MK-5890 reduced in an isotype-dependent and dose-dependent manner circulating, but not tumor-infiltrating T-cell numbers in these mouse models. In rhesus monkey and human patients, reduction in circulating T cells was transient and less pronounced than in mouse. MK-5890 induced transient elevation of chemokines MCP-1, MIP-1α, and MIP-1β in the serum of mice, rhesus monkeys and patients with cancer. MK-5890 was well tolerated in rhesus monkeys and systemic exposure to MK-5890 was associated with CD27 occupancy at all doses.

Conclusions

MK-5890 is a novel CD27 agonistic antibody with the potential to complement the activity of PD-1 checkpoint inhibition in cancer immunotherapy and is currently undergoing clinical evaluation.

Agonistic CD27 antibody potency is determined by epitope-dependent receptor clustering augmented through Fc-engineering

Agonistic CD27 monoclonal antibodies (mAb) have demonstrated impressive anti-tumour efficacy in multiple preclinical models but modest clinical responses. This might reflect current reagents delivering suboptimal CD27 agonism. Here, using a novel panel of CD27 mAb including a clinical candidate, we investigate the determinants of CD27 mAb agonism. Epitope mapping and in silico docking analysis show that mAb binding to membrane-distal and external-facing residues are stronger agonists. However, poor epitope-dependent agonism could partially be overcome by Fc-engineering, using mAb isotypes that promote receptor clustering, such as human immunoglobulin G1 (hIgG1, h1) with enhanced affinity to Fc gamma receptor (FcγR) IIb, or hIgG2 (h2). This study provides the critical knowledge required for the development of agonistic CD27 mAb that are potentially more clinically efficacious.

The Implementation of TNFRSF Co-Stimulatory Domains in CAR-T Cells for Optimal Functional Activity

The Tumor Necrosis Factor Receptor Superfamily (TNFRSF) is a large and important immunoregulatory family that provides crucial co-stimulatory signals to many if not all immune effector cells. Each co-stimulatory TNFRSF member has a distinct expression profile and a unique functional impact on various types of cells and at different stages of the immune response. Correspondingly, exploiting TNFRSF-mediated signaling for cancer immunotherapy has been a major field of interest, with various therapeutic TNFRSF-exploiting anti-cancer approaches such as 4-1BB and CD27 agonistic antibodies being evaluated (pre)clinically. A further application of TNFRSF signaling is the incorporation of the intracellular co-stimulatory domain of a TNFRSF into so-called Chimeric Antigen Receptor (CAR) constructs for CAR-T cell therapy, the most prominent example of which is the 4-1BB co-stimulatory domain included in the clinically approved product Kymriah. In fact, CAR-T cell function can be clearly influenced by the unique co-stimulatory features of members of the TNFRSF. Here, we review a select group of TNFRSF members (4-1BB, OX40, CD27, CD40, HVEM, and GITR) that have gained prominence as co-stimulatory domains in CAR-T cell therapy and illustrate the unique features that each confers to CAR-T cells.

Immunotherapy of Cancer by Targeting Regulatory T cells

Regulatory T (Treg) cells maintain immune homeostasis by inhibiting abnormal/overactive immune responses to both autogenic and nonautogenic antigens. Treg cells play an important role in immune tolerance, autoimmune diseases, infectious diseases, organ transplantation, and tumor diseases. Treg cells have two functional characteristics: T cell anergy and immunosuppression. Treg cells remain immune unresponsive to high concentrations of interleukin-2 and anti-CD3 monoclonal antibodies. In addition, the activation of Treg cells after TCR-mediated signal stimulation inhibits the activation and proliferation of effector T cells. In the process of tumor development, Treg cells accumulate locally in the tumor and lead to tumor escape by inducing anergy and immunosuppression. It is believed that targeted elimination of Treg cells can activate tumor-specific effector T cells and improve the efficiency of cancer immunotherapy. Therefore, inhibition/clearance of Treg cells is a promising strategy for enhancing antitumor immunity. Here, we review studies of cancer immunotherapies targeting Treg cells.

Targeting the CD27-CD70 Pathway to Improve Outcomes in Both Checkpoint Immunotherapy and Allogeneic Hematopoietic Cell Transplantation

Immune checkpoint inhibitor therapies and allogeneic hematopoietic cell transplant (alloHCT) represent two distinct modalities that offer a chance for long-term cure in a diverse array of malignancies and have experienced many breakthroughs in recent years. Herein, we review the CD27-CD70 co-stimulatory pathway and its therapeutic potential in 1) combination with checkpoint inhibitor and other immune therapies and 2) its potential ability to serve as a novel approach in graft-versus-host disease (GVHD) prevention. We further review recent advances in the understanding of GVHD as a complex immune phenomenon between donor and host immune systems, particularly in the early stages with mixed chimerism, and potential novel therapeutic approaches to prevent the development of GVHD.

Single-cell immune checkpoint landscape of PBMCs stimulated with Candida albicans

Immune checkpoints play various important roles in tumour immunity, which usually contribute to T cells’ exhaustion, leading to immunosuppression in the tumour microenvironment. However, the roles of immune checkpoints in infectious diseases, especially fungal infection, remain elusive. Here, we reanalyzed a recent published single-cell RNA-sequencing (scRNA-seq) data of peripheral blood mononuclear cells (PBMCs) stimulated with Candida albicans (C. albicans), to explore the expression patterns of immune checkpoints after C. albicans bloodstream infection. We characterized the heterogeneous pathway activities among different immune cell subpopulations after C. albicans infection. The CTLA-4 pathway was up-regulated in stimulated CD4⁺ and CD8⁺ T cells, while the PD-1 pathway showed high activity in stimulated plasmacytoid dendritic cell (pDC) and monocytes. Importantly, we found that immunosuppressive checkpoints HAVCR2 and LAG3 were only expressed in stimulated NK and CD8⁺ T cells, respectively. Their viabilities were validated by flow cytometry. We also identified three overexpressed genes (ISG20, LY6E, ISG15) across all stimulated cells. Also, two monocyte-specific overexpressed genes (SNX10, IDO1) were screened out in this study. Together, these results supplemented the landscape of immune checkpoints in fungal infection, which may serve as potential therapeutic targets for C. albicans infection. Moreover, the genes with the most relevant for C. albicans infection were identified in this study.

Conditioning treatment with CD27 Ab enhances expansion and antitumor activity of adoptively transferred T cells in mice

Cyclophosphamide plus fludarabine (C/F) are currently used to improve the expansion and effectiveness of adoptive cell therapy (ACT). However, these chemotherapeutics cause pan-leukopenia and adverse events, suggesting that safer and more effective conditioning treatments are needed to improve ACT outcomes. Previously, we reported that varlilumab, a CD27-targeting antibody, mediates T_reg -preferential T cell depletion, CD8-T cell dominant costimulation, and systemic immune activation in hCD27 transgenic mice and cancer patients. We reasoned that the activities induced by varlilumab may provide an effective conditioning regimen for ACT. Varlilumab pretreatment of hCD27^+/+mCD27 ^{− /−} mice resulted in prominent proliferation of transferred T cells isolated from wild-type mice. These studies uncovered a critical role for CD27 signaling for the expansion of transferred T cells, as transfer of T cells from CD27 deficient mice or treatment with a CD70 blocking antibody greatly reduced their proliferation. In this model, varlilumab depletes endogenous hCD27^+/+ T cells and blocks their subsequent access to CD70, allowing for more CD70 costimulation available to the mCD27^+/+ transferred T cells. CD27-targeted depletion led to a greater expansion of transferred T cells compared to C/F conditioning and resulted in longer median survival and more cures than C/F conditioning in the E.G7 tumor model receiving OT-I cell therapy. We propose that translation of this work could be achieved through engineering of T cells for ACT to abrogate varlilumab binding but preserve CD70 ligation. Thus, varlilumab could be an option to chemotherapy as a conditioning regimen for ACT.

Emerging immunotherapy targets in lung cancer

Immunotherapy has become the mainstay for lung cancer treatment, providing sustained therapeutic responses and improved prognosis compared with those obtained with surgery, chemotherapy, radiotherapy, and targeted therapy. It has the potential for anti-tumor treatment and killing tumor cells by activating human immunity and has moved the targets of anti-cancer therapy from malignant tumor cells to immune cell subsets. Two kinds of immune checkpoints, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and programmed death-1 (PD-1)/programmed death ligand 1 (PD-L1), are the main targets of current immunotherapy in lung cancer. Despite the successful outcomes achieved by immune checkpoint inhibitors, a small portion of lung cancer patients remain unresponsive to checkpoint immunotherapy or may ultimately become resistant to these agents as a result of the complex immune modulatory network in the tumor microenvironment. Therefore, it is imperative to exploit novel immunotherapy targets to further expand the proportion of patients benefiting from immunotherapy. This review summarizes the molecular features, biological function, and clinical significance of several novel checkpoints that have important roles in lung cancer immune responses beyond the CTLA-4 and PD-1/PD-L1 axes, including the markers of co-inhibitory and co-stimulatory T lymphocyte pathways and inhibitory markers of macrophages and natural killer cells.

Safety and activity of varlilumab, a novel and first-in-class agonist anti-CD27 antibody, for hematologic malignancies

CD27, a costimulatory molecule on T cells, induces intracellular signals mediating cellular activation, proliferation, effector function, and cell survival on binding to its ligand, CD70. Varlilumab, a novel, first-in-class, agonist immunoglobulin G1 anti-CD27 antibody, mediates antitumor immunity and direct killing of CD27+ tumor cells in animal models. This first-in-human, dose-escalation, and expansion study evaluated varlilumab in patients with hematologic malignancies. Primary objectives were to assess safety and the maximum tolerated and optimal biologic doses of varlilumab. Secondary objectives were to evaluate pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity. In a 3 + 3 dose-escalation design, 30 patients with B-cell (n = 25) or T-cell (n = 5) malignancies received varlilumab (0.1, 0.3, 1, 3, or 10 mg/kg IV) as a single dose with a 28-day observation period, followed by weekly dosing (4 doses per cycle, up to 5 cycles, depending on tumor response). In an expansion cohort, 4 additional patients with Hodgkin lymphoma received varlilumab at 0.3 mg/kg every 3 weeks (4 doses per cycle, up to 5 cycles). No dose-limiting toxicities were observed. Treatment-related adverse events, generally grade 1 to 2, included fatigue, decreased appetite, anemia, diarrhea, and headache. Exposure was linear and dose-proportional across dose groups and resulted in increases in proinflammatory cytokines and soluble CD27. One patient with stage IV Hodgkin lymphoma experienced a complete response and remained in remission at >33 months with no further anticancer therapy. These data support further investigation of varlilumab for hematologic malignancies, particularly in combination approaches targeting nonredundant immune regulating pathways. This trial was registered at www.clinicaltrials.gov as #NCT01460134.

Engaging the Innate and Adaptive Antitumor Immune Response in Lymphoma

Immunotherapy has emerged as a powerful therapeutic strategy for many malignancies, including lymphoma. As in solid tumors, early clinical trials have revealed that immunotherapy is not equally efficacious across all lymphoma subtypes. For example, immune checkpoint inhibition has a higher overall response rate and leads to more durable outcomes in Hodgkin lymphomas compared to non-Hodgkin lymphomas. These observations, combined with a growing understanding of tumor biology, have implicated the tumor microenvironment as a major determinant of treatment response and prognosis. Interactions between lymphoma cells and their microenvironment facilitate several mechanisms that impair the antitumor immune response, including loss of major histocompatibility complexes, expression of immunosuppressive ligands, secretion of immunosuppressive cytokines, and the recruitment, expansion, and skewing of suppressive cell populations. Accordingly, treatments to overcome these barriers are being rapidly developed and translated into clinical trials. This review will discuss the mechanisms of immune evasion, current avenues for optimizing the antitumor immune response, clinical successes and failures of lymphoma immunotherapy, and outstanding hurdles that remain to be addressed.

Management of Drug Resistance in Mantle Cell Lymphoma

Mantle cell lymphoma (MCL) is a rare but aggressive B-cell hemopathy characterized by the translocation t(11;14)(q13;q32) that leads to the overexpression of the cell cycle regulatory protein cyclin D1. This translocation is the initial event of the lymphomagenesis, but tumor cells can acquire additional alterations allowing the progression of the disease with a more aggressive phenotype and a tight dependency on microenvironment signaling. To date, the chemotherapeutic-based standard care is largely inefficient and despite the recent advent of different targeted therapies including proteasome inhibitors, immunomodulatory drugs, tyrosine kinase inhibitors, relapses are frequent and are generally related to a dismal prognosis. As a result, MCL remains an incurable disease. In this review, we will present the molecular mechanisms of drug resistance learned from both preclinical and clinical experiences in MCL, detailing the main tumor intrinsic processes and signaling pathways associated to therapeutic drug escape. We will also discuss the possibility to counteract the acquisition of drug refractoriness through the design of more efficient strategies, with an emphasis on the most recent combination approaches.

Development of CDX-527: a bispecific antibody combining PD-1 blockade and CD27 costimulation for cancer immunotherapy

CD27 is a costimulatory molecule that provides a complementary target to the PD-1/PD-L1 checkpoint axis on T cells. Combining a CD27 agonist antibody with PD-1/PD-L1 blockade has shown synergistic antitumor activity in preclinical models, which led to clinical studies of the combination in cancer patients. We theorized that coupling CD27 costimulation with PD-1/PD-L1 blockade in a bispecific antibody (BsAb) may provide greater immune activating properties than combining the individual mAbs due to enhanced CD27 activation by cross-linking through PD-L1 and Fc receptors. To test this approach, we developed CDX-527, a tetravalent PD-L1xCD27 IgG1-scFv BsAb. CDX-527 potently inhibits PD-1 signaling and induces CD27-mediated T cell costimulation through PD-L1 cross-linking. In mixed lymphocyte reaction assays, CDX-527 is more potent than the combination of the parental antibodies, suggesting that cross-linking through both Fc receptors and PD-L1 results in enhanced CD27 agonist activity. CDX-527 was shown to mediate effector function against tumor cells overexpressing either CD27 or PD-L1. In human CD27 transgenic mice, we observed that antigen-specific T cell responses to a vaccine are greatly enhanced with a surrogate PD-L1xCD27 BsAb. Furthermore, the BsAb exhibits greater antitumor activity than the combination of the parental antibodies in a syngeneic lymphoma model. A pilot study of CDX-527 in cynomolgus macaques confirmed a mAb-like pharmacokinetic profile without noted toxicities. These studies demonstrate that CDX-527 effectively combines PD-1 blockade and CD27 costimulation into one molecule that is more potent than combination of the parental antibodies providing the rationale to advance this BsAb toward clinical studies in cancer patients.

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.

The progress and confusion of anti-PD1/PD-L1 immunotherapy for patients with advanced non-small cell lung cancer

Recently, immunotherapy has evolved into a true treatment modality with the approval of PD-1 and PD-L1 inhibitors as the standard care for first-line treatment in patients with non-small cell lung cancer (NSCLC). Until now, for patients with advanced NSCLC, treatment of targeting immune checkpoints reveals a promising survival benefit, and some patients even get long term survive, which creates a paradigm shift in NSCLC treatment. However, many issues or problems are also appearing in clinical practice, such as the lower overall efficacy rate (20-40%), treatment modes, populations choice of immunotherapy, drug resistance, and safety, etc. Thus, in this review, we will mainly summarize and discuss the recent development and confusion of PD-1/PD-L1 inhibitors for advanced NSCLC patients based on current clinical studies.

Knowledge is power-Rational design of cancer immunotherapy

Discussion on how our increasing knowledge on tumor immunity and host defense mechanisms has drastically changed our ability to improve cancer outcomes through the rational design of immunotherapies.

Immune-phenotyping of pleomorphic dermal sarcomas suggests this entity as a potential candidate for immunotherapy

BACKGROUND

Pleomorphic dermal sarcomas (PDS) are sarcomas of the skin with local recurrences in up to 28% of cases, and distant metastases in up to 20%. Although recent evidence provides a strong rational to explore immunotherapeutics in solid tumors, nothing is known about the immune environment of PDS.

METHODS

In the current study, a comprehensive immune-phenotyping of 14 PDS using RNA and protein expression analyses, as well as quantitative assessment of immune cells using an image-analysis tool was performed.

RESULTS

Three out of 14 PDS revealed high levels of CD8-positive tumor-infiltrating T-lymphocytes (TILs), also showing elevated levels of immune-related cytokines such as IL1A, IL2, as well as markers that were very recently linked to enhanced response of immunotherapy in malignant melanoma, including CD27, and CD40L. Using a multivariate analysis, we found a number of differentially expressed genes in the CD8-high group including: CD74, LYZ and HLA-B, while the remaining cases revealed enhanced levels of immune-suppressive cytokines including CXCL14. The "CD8-high" PDS showed strong MHC-I expression and revealed infiltration by PD-L1-, PD-1- and LAG-3-expressing immune cells. Tumor-associated macrophages (TAMs) predominantly consisted of CD68 + , CD163 + , and CD204 + M2 macrophages showing an accentuation at the tumor invasion front.

CONCLUSIONS

Together, we provide first explorative evidence about the immune-environment of PDS tumors that may guide future decisions whether individuals presenting with advanced PDS could qualify for immunotherapeutic options.

Bispecific Antibodies in the Treatment of Hematologic Malignancies

Monoclonal antibody therapies are an important approach for the treatment of hematologic malignancies, but typically show low single‐agent activity. Bispecific antibodies, however, redirect immune cells to the tumor for subsequent lysis, and preclinical and accruing clinical data support single‐agent efficacy of these agents in hematologic malignancies, presaging an exciting era in the development of novel bispecific formats. This review discusses recent developments in this area, highlighting the challenges in delivering effective immunotherapies for patients.

Tumor necrosis factor receptor-2 (TNFR2): an overview of an emerging drug target

INTRODUCTION

Tumor necrosis factor (TNF) receptor 2 (TNFR2) is one of two receptors of the cytokines, TNF and lymphotoxin-α. TNFR1 is a strong inducer of proinflammatory activities. TNFR2 has proinflammatory effects too, but it also elicits strong anti-inflammatory activities and has protective effects on oligodendrocytes, cardiomyocytes, and keratinocytes. The protective and anti-inflammatory effects of TNFR2 may explain why TNF inhibitors failed to be effective in diseases such as heart failure or multiple sclerosis, where TNF has been strongly implicated as a driving force. Stimulatory and inhibitory TNFR2 targeting hence attracts considerable interest for the treatment of autoimmune diseases and cancer. Areas covered: Based on a brief description of the pathophysiological importance of the TNF-TNFR1/2 system, we discuss the potential applications of TNFR2 targeting therapies. We also debate TNFR2 activation as a way forward in the search for TNFR2-specific agents. Expert opinion: The use of TNFR2 to target regulatory T-cells is attractive, but this approach is just one amongst many suitable targets. With respect to its preference for Treg stimulation and protection of non-immune cells, TNFR2 is more unique and thus offers opportunities for translational success.

Role of FcγRs in Antibody-Based Cancer Therapy

Monoclonal antibodies can mediate antitumor activity by multiple mechanisms. They can bind directly to tumor receptors resulting in tumor cell death, or can bind to soluble growth factors, angiogenic factors, or their cognate receptors blocking signals required for tumor cell growth or survival. Monoclonal antibodies, upon binding to tumor cell, can also engage the host's immune system to mediate immune-mediated destruction of the tumor. The Fc portion of the antibody is essential in engaging the host immune system by fixing complement resulting in complement-mediated cytotoxicity (CDC) of the tumor, or by engaging Fc receptors for IgG (FcγR) expressed by leukocytes leading to antibody-dependent cellular cytotoxicity (ADCC) or antibody-dependent cellular phagocytosis (ADCP) of tumor cells. Antibodies whose Fc portion preferentially engage activating FcγRs have shown greater inhibition of tumor growth and metastasis. Monoclonal antibodies can also stimulate the immune system by binding to targets expressed on immune cells. These antibodies may stimulate antitumor immunity by antagonizing a negative regulatory signal, agonizing a costimulatory signal, or depleting immune cells that are inhibitory. The importance of Fc:FcγR interactions in antitumor therapy for each of these mechanisms have been demonstrated in both mouse models and clinical trials and will be the focus of this chapter.

Promising vaccines for treating glioblastoma

INTRODUCTION

Conventional therapies for glioblastoma  (GBM) typically fail to provide lasting antitumor benefits, owing to their inability to specifically eliminate all malignant cells. Cancer vaccines are currently being evaluated as a means to direct the adaptive immune system to target residual GBM cells that remain following standard-of-care treatment.

AREAS COVERED

In this review, we provide an overview of the more noteworthy cancer vaccines that are under investigation for the treatment of GBM, as well as potential future directions that may enhance GBM-vaccine effectiveness.

EXPERT OPINION

To date, no cancer vaccines have been proven effective against GBM; however, only a few have reached phase III clinical testing. Clinical immunological monitoring data suggest that GBM vaccines are capable of stimulating immune responses reactive to GBM antigens, but whether these responses have an appreciable antitumor effect on GBM is still uncertain. Nevertheless, there have been several promising outcomes in early phase clinical trials, which lend encouragement to this area of study. Further studies with GBM vaccines are, therefore, warranted.

A Single-Chain-Based Hexavalent CD27 Agonist Enhances T Cell Activation and Induces Anti-Tumor Immunity

Tumor necrosis factor receptor superfamily member 7 (TNFRSF7, CD27), expressed primarily by T cells, and its ligand CD27L (TNFSF7, CD70) provide co-stimulatory signals that boost T cell activation, differentiation, and survival. Agonistic stimulation of CD27 is therefore a promising therapeutic concept in immuno-oncology intended to boost and sustain T cell driven anti-tumor responses. Endogenous TNFSF/TNFRSF-based signal transmission is a structurally well-defined event that takes place during cell-to-cell-based contacts. It is well-established that the trimeric-trivalent TNFSF-receptor binding domain (TNFSF-RBD) exposed by the conducting cell and the resulting multi-trimer-based receptor clustering on the receiving cell are essential for agonistic signaling. Therefore, we have developed HERA-CD27L, a novel hexavalent TNF receptor agonist (HERA) targeting CD27 and mimicking the natural signaling concept. HERA-CD27L is composed of a trivalent but single-chain CD27L-receptor-binding-domain (scCD27L-RBD) fused to an IgG1 derived silenced Fc-domain serving as dimerization scaffold. The hexavalent agonist significantly boosted antigen-specific T cell responses while having no effect on non-specific T cells and was superior over stabilized recombinant trivalent CD27L. In addition, HERA-CD27L demonstrated potent single-agent anti-tumor efficacy in two different syngeneic tumor models, MC38-CEA and CT26wt. Furthermore, the combination of HERA-CD27L and an anti-PD-1 antibody showed additive anti-tumor effects highlighting the importance of both T cell activation and checkpoint inhibition in anti-tumor immunity. In this manuscript, we describe the development of HERA-CD27L, a true CD27 agonist with a clearly defined forward-signaling mechanism of action.

CD27 stimulation unveils the efficacy of linked class I/II peptide vaccines in poorly immunogenic tumors by orchestrating a coordinated CD4/CD8 T cell response

Despite their promise, tumor-specific peptide vaccines have limited efficacy. CD27 is a costimulatory molecule expressed on CD4+ and CD8+ T cells that is important in immune activation. Here we determine if a novel CD27 agonist antibody (αhCD27) can enhance the antitumor T cell response and efficacy of peptide vaccines. We evaluated the effects of αhCD27 on the immunogenicity and antitumor efficacy of whole protein, class I-restricted, and class II-restricted peptide vaccines using a transgenic mouse expressing human CD27. We found that αhCD27 preferentially enhances the CD8+ T cell response in the setting of vaccines comprised of linked class I and II ovalbumin epitopes (SIINFEKL and TEWTSSNVMEERKIKV, respectively) compared to a peptide vaccine comprised solely of SIINFEKL, resulting in the antitumor efficacy of adjuvant αhCD27 against intracranial B16.OVA tumors when combined with vaccines containing linked class I/II ovalbumin epitopes. Indeed, we demonstrate that this efficacy is both CD8- and CD4-dependent and αhCD27 activity on ovalbumin-specific CD4+ T cells is necessary for its adjuvant effect. Importantly for clinical translation, a linked universal CD4+ helper epitope (tetanus P30) was sufficient to instill the efficacy of SIINFEKL peptide combined with αhCD27, eliminating the need for a tumor-specific class II-restricted peptide. This approach unveiled the efficacy of a class I-restricted peptide vaccine derived from the tumor-associated Trp2 antigen in mice bearing intracranial B16 tumors. CD27 agonist antibodies combined with peptide vaccines containing linked tumor-specific CD8+ epitopes and tumor-specific or universal CD4+ epitopes enhance the efficacy of active cancer immunotherapy.

The opposing roles of CD4+ T cells in anti-tumour immunity

Cancer immunotherapy focuses mainly on anti-tumour activity of CD8+ cytotoxic T lymphocytes (CTLs). CTLs can directly kill all tumour cell types, provided they carry recognizable antigens. However, CD4+ T cells also play important roles in anti-tumour immunity. CD4+ T cells can either suppress or promote the anti-tumour CTL response, either in secondary lymphoid organs or in the tumour. In this review, we highlight opposing mechanisms of conventional and regulatory T cells at both sites. We outline how current cancer immunotherapy strategies affect both subsets and how selective modulation of each subset is important to maximize the clinical response of cancer patients.

Regulatory T cells (Tregs): A major immune checkpoint to consider in combinatorial therapeutic HIV-1 vaccines

The field of immunotherapeutics is living an exceptional time as new antibodies that take brakes off T-cells and unleash them on tumours are being approved by the US-Food and Drug Administration (FDA). For the design and development of an HIV-1 therapeutic-vaccine, one would need preferably to shift the balance T-effectors/T-regulatory cells (Teff/Tregs) towards effectors to improve vaccine-specific immune-responses. Given the success with the new immune-checkpoint-blockers (ICB), it is an appropriate time for HIV-1 field to seize this opportunity and develop new therapeutic vaccine-strategies that take into consideration ICB and other immunomodulators such as cytokines. While the vaccine is important to stimulate HIV-1-specific T-cell responses, cytokines will support the expansion of the stimulated virus-specific T-cells and ICB will reverse exhaustion and unchain cytotoxic T-cells. In this commentary, we will spotlight Tregs as another major brake for T-cell immunity and address the main stumbling-blocks that often blurs HIV-1-specific-Tregs status with regards to their role (beneficial or detrimental) and we will recall some proof-of-concept studies where therapeutic immunization skewed the HIV-1-specific response from Tregs to Teffs which impacts on the magnitude of viral replication. We will also suggest some strategies to shift the balance towards Teffs and potentiate HIV-1-specific immune-responses.

New strategies in immunotherapy for lung cancer: beyond PD-1/PD-L1

Immunotherapy has significantly altered the treatment landscape for many cancers, including non-small cell lung cancer (NSCLC). Currently approved immuno-oncology agents for lung cancer are aimed at the reversal of immune checkpoints, programmed death protein-1 (PD-1) and programmed death ligand-1 (PD-L1). Although responses to checkpoint inhibitors are encouraging, and in some cases durable, these successes are not universal among all treated patients. In order to optimize our treatment approach utilizing immunotherapy, we must better understand the interaction between cancer and the immune system and evasion mechanisms. In this review, we will provide an overview of the immune system and cancer, and review novel therapies that promote tumor antigen release for immune system detection, activate the effector T-cell response, and reverse inhibitory antitumor signals.