CD40L gene therapy tilts the myeloid cell profile and promotes infiltration of activated T lymphocytes

Targeting the innate immune system in pediatric and adult AML

While the introduction of T cell-based immunotherapies has improved outcomes in many cancer types, the development of immunotherapies for both adult and pediatric AML has been relatively slow and limited. In addition to the need to identify suitable target antigens, a better understanding of the immunosuppressive tumor microenvironment is necessary for the design of novel immunotherapy approaches. To date, most immune characterization studies in AML have focused on T cells, while innate immune lineages such as monocytes, granulocytes and natural killer (NK) cells, received less attention. In solid cancers, studies have shown that innate immune cells, such as macrophages, myeloid-derived suppressor cells and neutrophils are highly plastic and may differentiate into immunosuppressive cells depending on signals received in their microenvironment, while NK cells appear to be functionally impaired. Hence, an in-depth characterization of the innate immune compartment in the TME is urgently needed to guide the development of immunotherapeutic interventions for AML. In this review, we summarize the current knowledge on the innate immune compartment in AML, and we discuss how targeting its components may enhance T cell-based- and other immunotherapeutic approaches.

Next-generation CD40 agonists for cancer immunotherapy

INTRODUCTION

There is a need for new therapies that can enhance response rates and broaden the number of cancer indications where immunotherapies provide clinical benefit. CD40 targeting therapies provide an opportunity to meet this need by promoting priming of tumor-specific T cells and reverting the suppressive tumor microenvironment. This is supported by emerging clinical evidence demonstrating the benefits of immunotherapy with CD40 antibodies in combination with standard of care chemotherapy.

AREAS COVERED

This review is focused on the coming wave of next-generation CD40 agonists aiming to improve efficacy and safety, using new approaches and formats beyond monospecific antibodies. Further, the current understanding of the role of different CD40 expressing immune cell populations in the tumor microenvironment is reviewed.

EXPERT OPINION

There are multiple promising next-generation approaches beyond monospecific antibodies targeting CD40 in immuno-oncology. Enhancing efficacy is the most important driver for this development, and approaches that maximize the ability of CD40 to both remodel the tumor microenvironment and boost the anti-tumor T cell response provide great opportunities to benefit cancer patients. Enhanced understanding of the role of different CD40 expressing immune cells in the tumor microenvironment may facilitate more efficient clinical development of these compounds.

Myeloid cell-targeted therapies for solid tumours

Myeloid cells are the most abundant immune components of the tumour microenvironment, where they have a variety of functions, ranging from immunosuppressive to immunostimulatory roles. The myeloid cell compartment comprises many different cell types, including monocytes, macrophages, dendritic cells and granulocytes, that are highly plastic and can differentiate into diverse phenotypes depending on cues received from their microenvironment. In the past few decades, we have gained a better appreciation of the complexity of myeloid cell subsets and how they are involved in tumour progression and resistance to cancer therapies, including immunotherapy. In this Review, we highlight key features of monocyte and macrophage biology that are being explored as potential targets for cancer therapies and what aspects of myeloid cells need a deeper understanding to identify rational combinatorial strategies to improve clinical outcomes of patients with cancer. We discuss therapies that aim to modulate the functional activities of myeloid cell populations, impacting their recruitment, survival and activity in the tumour microenvironment, acting at the level of cell surface receptors, signalling pathways, epigenetic machinery and metabolic regulators. We also describe advances in the development of genetically engineered myeloid cells for cancer therapy.

Immune Checkpoint and Other Receptor-Ligand Pairs Modulating Macrophages in Cancer: Present and Prospects

Immunotherapy, especially immune checkpoint blocking, has become the primary anti-tumor treatment in recent years. However, the current immune checkpoint inhibitor (ICI) therapy is far from satisfactory. Macrophages are a key component of anti-tumor immunity as they are a common immune cell subset in tumor tissues and act as a link between innate and adaptive immunity. Hence, understanding the regulation of macrophage activation in tumor tissues by receptor-ligand interaction will provide promising macrophage-targeting strategies to complement current adaptive immunity-based immunotherapy and traditional anti-tumor treatment. This review aims to offer a systematic summary of the current advances in number, structure, expression, biological function, and interplay of immune checkpoint and other receptor-ligand between macrophages and tumor cells.

Immunobiology of high-grade serous ovarian cancer: lessons for clinical translation

Treatment of high-grade serous ovarian cancer (HGSOC) remains challenging. Although HGSOC can potentially be responsive to immunotherapy owing to endogenous immunity at the molecular or T cell level, immunotherapy for this disease has fallen short of expectations to date. This Review proposes a working classification for HGSOC based on the presence or absence of intraepithelial T cells, and elaborates the putative mechanisms that give rise to such immunophenotypes. These differences might explain the failures of existing immunotherapies, and suggest that rational therapeutic approaches tailored to each immunophenotype might meet with improved success. In T cell-inflamed tumours, treatment could focus on mobilizing pre-existing immunity and strengthening the activation of T cells embedded in intraepithelial tumour myeloid niches. Conversely, in immune-excluded and immune-desert tumours, treatment could focus on restoring inflammation by reprogramming myeloid cells, stromal cells and vascular epithelial cells. Poly(ADP-ribose) polymerase (PARP) inhibitors, low-dose radiotherapy, epigenetic drugs and anti-angiogenesis therapy are among the tools available to restore T cell infiltration in HGSOC tumours and could be implemented in combination with vaccines and redirected T cells.

Analysis of physical activity and plasma levels of soluble CD40 and CD40L in older people with gastrointestinal tract cancer

Regular physical activity prevents and treats cancer patients by assisting and improving the immune system. Co-stimulatory molecules that activate the immune system have been studied in cancer, such as immune checkpoint molecules of the CD40/CD40L pathway. This study aimed to characterize plasma levels of soluble CD40 (sCD40) and CD40 ligand (sCD40L) in older people with gastrointestinal tract (GIT) cancer and associate results with physical activity. This prospective and exploratory cohort study was performed with 24 older people with GIT cancer and 23 healthy elderly individuals as controls. Physical activity level was classified as active or sedentary according to the International Physical Activity Questionnaire-Short Form (IPAQ-SF). Plasma levels of sCD40 and sCD40L were determined using Enzyme-Linked Immunosorbent Assay. Plasma levels of sCD40 were higher, while sCD40L were lower (p = 0.0171) in older people with GIT cancer than controls (p = 0.0038). Regarding physical activity, active older people with GIT cancer presented lower plasma levels of sCD40 and sCD40L than those sedentary with GIT cancer (p = 0.0228 and p = 0.0236), respectively. Our findings suggest that GIT cancer stimulates the immune system in older people, elevates levels of sCD40, and reduces levels of sCD40L. Physical activity may be a protective factor for the immune system of these patients since it acts on sCD40/sCD40L pathway.

Myeloid antigen-presenting cell niches sustain antitumor T cells and license PD-1 blockade via CD28 costimulation

The mechanisms regulating exhaustion of tumor-infiltrating lymphocytes (TIL) and responsiveness to PD-1 blockade remain partly unknown. In human ovarian cancer, we show that tumor-specific CD8+ TIL accumulate in tumor islets, where they engage antigen and upregulate PD-1, which restrains their functions. Intraepithelial PD-1+CD8+ TIL can be, however, polyfunctional. PD-1+ TIL indeed exhibit a continuum of exhaustion states, with variable levels of CD28 costimulation, which is provided by antigen-presenting cells (APC) in intraepithelial tumor myeloid niches. CD28 costimulation is associated with improved effector fitness of exhausted CD8+ TIL and is required for their activation upon PD-1 blockade, which also requires tumor myeloid APC. Exhausted TIL lacking proper CD28 costimulation in situ fail to respond to PD-1 blockade, and their response may be rescued by local CTLA-4 blockade and tumor APC stimulation via CD40L.

Intratumoral immunostimulatory AdCD40L gene therapy in patients with advanced solid tumors

AdCD40L is a replication-deficient virus carrying the gene for CD40 ligand which has previously been evaluated in patients with urothelial cancer and malignant melanoma. Herein, we present the results of repeated intratumoral injections of AdCD40L in seven patients with metastatic solid cancer. One patient who developed urothelial cancer derived from a renal transplant was treated with repeated injections of AdCD40L alone. The remaining patients suffered from cholangiocarcinoma, kidney, breast, rectal, or ovarian cancer and received AdCD40L repeatedly (4x) in combination with cyclophosphamide. The treatment was safe and generally well-tolerated. Two patients had clinical benefit of the treatment and one of them was accepted for re-treatment. Circulating proinflammatory cytokines were commonly increased after treatment, but save for TNFα, significances were not reached which could be due to the low number of patients. Similar to earlier findings in AdCD40L-treated melanoma patients, IL8 plasma levels were high in the present study. In conclusion, gene therapy by repeated intratumoral AdCD40L injections alone, or in combination with cyclophosphamide, is feasible and safe in patients with solid cancers. The potential of intratumoral CD40L gene transfer as treatment of cancer was illustrated by the clinical improvement in two out of seven patients.

Design and application of oncolytic viruses for cancer immunotherapy

The approval of the first oncolytic virus (OV) for the treatment of metastatic melanoma and the recent discovery that the use of oncolytic viruses may enhance cancer immunotherapies targeted against various immune checkpoint proteins have attracted great interest in the field of cancer virotherapy. OVs are designed to target and kill cancer cells leaving normal cell unharmed. OV infection and concomitant cancer cell killing stimulate anti-tumour immunity and modulates tumour microenvironment towards less immunosuppressive phenotype. The intrinsic capacity of OVs to turn immunologically cold tumours into immunologically hot tumours, and to increase immune cell and cytokine infiltration, can be further enhanced by arming OVs with transgenes that increase their immunostimulatory activities and direct immune responses specifically towards cancer cells. These OVs, specifically engineered to be used as cancer immunotherapeutics, can be synergized with other immune modulators or cytotoxic agents to achieve the most potent immunotherapy for cancer.

IL-6 Signaling Blockade during CD40-Mediated Immune Activation Favors Antitumor Factors by Reducing TGF-β, Collagen Type I, and PD-L1/PD-1

IL-6 plays a role in cancer pathogenesis via its connection to proteins involved in the formation of desmoplastic stroma and to immunosuppression by driving differentiation of myeloid suppressor cells together with TGF-β. Inhibition of IL-6 signaling in the tumor microenvironment may, thus, limit desmoplasia and myeloid suppressor cell differentiation. CD40 signaling can further revert myeloid cell differentiation toward antitumor active phenotypes. Hence, the simultaneous use of IL-6 blockade with CD40 stimuli may tilt the tumor microenvironment to promote antitumor immune responses. In this paper, we evaluated the mechanisms of LOAd713, an oncolytic adenovirus designed to block IL-6R signaling and to provide myeloid cell activation via a trimerized membrane-bound isoleucine zipper (TMZ) CD40L. LOAd713-infected pancreatic cancer cells were killed by oncolysis, whereas infection of stellate cells reduced factors involved in stroma formation, including TGF-β-1 and collagen type I. Virus infection prevented IL-6/GM-CSF-mediated differentiation of myeloid suppressors, but not CD163 macrophages, whereas infection of dendritic cells led to upregulation of maturation markers, including CD83, CD86, IL-12p70, and IFN-γ. Further, IL-6R blockade prevented upregulation of programed death ligand 1 (PD-L1) and PD-1 on the stimulated dendritic cells. These results suggest that LOAd713 can kill infected tumor cells and has the capacity to affect the tumor microenvironment by stimulating stellate cells and myeloid suppressors with TMZ-CD40L and IL-6R blockade. Gene transfer of murine TMZ-CD40L prolonged survival in an animal model. LOAd713 may be an interesting therapeutic option for cancers connected to IL-6 signaling, such as pancreatic cancer.

Trial Watch: Immunostimulatory monoclonal antibodies for oncological indications

The goal of cancer immunotherapy is to establish new or boost pre-existing anticancer immune responses that eradicate malignant cells while generating immunological memory to prevent disease relapse. Over the past few years, immunomodulatory monoclonal antibodies (mAbs) that block co-inhibitory receptors on immune effectors cells - such as cytotoxic T lymphocyte-associated protein 4 (CTLA4), programmed cell death 1 (PDCD1, best known as PD-1) - or their ligands - such as CD274 (best known as PD-L1) - have proven very successful in this sense. As a consequence, many of such immune checkpoint blockers (ICBs) have already entered the clinical practice for various oncological indications. Considerable attention is currently being attracted by a second group of immunomodulatory mAbs, which are conceived to activate co-stimulatory receptors on immune effector cells. Here, we discuss the mechanisms of action of these immunostimulatory mAbs and summarize recent progress in their preclinical and clinical development.

Shaping the Tumor Stroma and Sparking Immune Activation by CD40 and 4-1BB Signaling Induced by an Armed Oncolytic Virus

Purpose: Pancreatic cancer is a severe indication with short expected survival despite surgery and/or combination chemotherapeutics. Checkpoint blockade antibodies are approved for several cancer indications, but pancreatic cancer has remained refractory. However, there are clinical data suggesting that stimulation of the CD40 pathway may be of interest for these patients. Oncolytic viruses armed with immunostimulatory genes represent an interesting approach. Herein, we present LOAd703, a designed adenovirus armed with trimerized CD40L and 4-1BBL that activates the CD40 and 4-1BB pathways, respectively. As many cells in the tumor stroma, including stellate cells and the infiltrating immune cells, express CD40 and some 4-1BB, we hypothesize that LOAd703 activates immunity and simultaneously modulates the biology of the tumor stroma.Experimental Design: Tumor, stellate, endothelial, and immune cells were infected by LOAd703 and investigated by flow cytometry, proteomics, and functional analyses.Results: LOAd703-infected pancreatic cell lines were killed by oncolysis, and the virus was more effective than standard-of-care gemcitabine. In in vivo xenograft models, LOAd703 efficiently reduced established tumors and could be combined with gemcitabine for additional effect. Infected stellate and tumor cells reduced factors that promote tumor growth (Spp-1, Gal-3, HGF, TGFβ and collagen type I), while chemokines were increased. Molecules involved in lymphocyte migration were upregulated on infected endothelial cells. Dendritic cells were robustly stimulated by LOAd703 to produce costimulators, cytokines and chemokines, and such DCs potently expanded both antigen-specific T cells and NK cells.Conclusions: LOAd703 is a potent immune activator that modulates the stroma to support antitumor responses. Clin Cancer Res; 23(19); 5846-57. ©2017 AACR.

Adenovirus-mediated CD40L gene transfer increases Teffector/Tregulatory cell ratio and upregulates death receptors in metastatic melanoma patients

Background and aims

Malignant melanoma is an aggressive tumor sensitive for immunotherapy such as checkpoint blockade antibodies. Still, most patients with late stage disease do not respond, and the side effects can be severe. Stimulation of the CD40 pathway to initiate anti-tumor immunity is a promising alternative. Herein, we demonstrate immune profiling data from melanoma patients treated with an adenovirus-based CD40 ligand gene therapy (AdCD40L).

Methods

Peripheral blood mononuclear cells and plasma were collected from malignant melanoma patients (n = 15) enrolled in a phase I/IIa study investigating intratumoral delivery of AdCD40L with or without low dose cyclophosphamide. Cells were analyzed by flow cytometry while plasma samples were analyzed by a multi-array proteomics.

Results

All patients had an increased Teffector/Tregulatory cell ratio post therapy. Simultaneously, the death receptors TNFR1 and TRAIL-R2 were significantly up-regulated post treatment. Stem cell factor (SCF), E-selectin, and CD6 correlated to enhanced overall survival while a high level of granulocytic myeloid-derived suppressor cells (gMDSCs), IL8, IL10, TGFb1, CCL4, PlGF and Fl3t ligand was highest in patients with short survival.

Conclusions

AdCD40L intratumoral injection induced desirable systemic immune effects that correlated to prolonged survival. Further studies using CD40 stimulation in malignant melanoma are warranted.

Trial registration The 002:CD40L trial “Phase I/IIa AdCD40L Immunogene Therapy for Malignant Melanoma and Other Solid Tumors” (clinicalTrials.gov identifier: NCT01455259) was registered at September 2011

Activation of myeloid and endothelial cells by CD40L gene therapy supports T-cell expansion and migration into the tumor microenvironment

CD40 is an interesting target in cancer immunotherapy due to its ability to stimulate T-helper 1 immunity via maturation of dendritic cells and to drive M2 to M1 macrophage differentiation. Pancreatic cancer has a high M2 content that has shown responsive to anti-CD40 agonist therapy and CD40 may thus be a suitable target for immune activation in these patients. In this study, a novel oncolytic adenovirus armed with a trimerized membrane-bound extracellular CD40L (TMZ-CD40L) was evaluated as a treatment of pancreatic cancer. Further, the CD40L mechanisms of action were elucidated in cancer models. The results demonstrated that the virus transferring TMZ-CD40L had oncolytic capacity in pancreatic cancer cells and could control tumor progression. TMZ-CD40L was a potent stimulator of human myeloid cells and T-cell responses. Further, CD40L-mediated stimulation increased tumor-infiltrating T cells in vivo, which may be due to a direct activation of endothelial cells to upregulate receptors for lymphocyte attachment and transmigration. In conclusion, CD40L-mediated gene therapy is an interesting concept for the treatment of tumors with high levels of M2 macrophages, such as pancreatic cancer, and an oncolytic virus as carrier of CD40L may further boost tumor killing and immune activation.

CAR T-Cell Therapy: The Role of Physical Barriers and Immunosuppression in Lymphoma

Chimeric antigen receptor (CAR) T-cells have shown remarkable results in patients with B-cell leukemia and lymphoma. However, while CAR T-cells have shown complete responses in a majority of patients with acute lymphoblastic leukemia (ALL), lymphomas are more difficult to treat. Different CAR designs and conditioning protocols seem to affect the persistence of patient responses. However, factors that determine if patients receiving the same CARs will respond or not remain obscure. In Sweden, a phase I/IIa trial using third-generation CAR T-cells is ongoing in which we intend to compare tumor biology and immunology, in each patient, to treatment response. CAR T-cell therapy is a powerful tool to add to the treatment options for this patient group but we need to perform the necessary basic research on the multifactorial mechanisms of action to give patients the best possible option of survival. Such studies are also crucial to expand the success of CAR T-cells beyond CD19+ B-cell malignancy. This review will focus on possible barriers of treating lymphoma to define factors that need to be investigated to develop the next generation of CAR T-cell therapy.

Immunostimulatory Gene Therapy Using Oncolytic Viruses as Vehicles

Immunostimulatory gene therapy has been developed during the past twenty years. The aim of immunostimulatory gene therapy is to tilt the suppressive tumor microenvironment to promote anti-tumor immunity. Hence, like a Trojan horse, the gene vehicle can carry warriors and weapons into enemy territory to combat the tumor from within. The most promising immune stimulators are those activating and sustaining Th1 responses, but even if potent effects were seen in preclinical models, many clinical trials failed to show objective responses in cancer patients. However, with new tools to control ongoing immunosuppression in cancer patients, immunostimulatory gene therapy is now emerging as an interesting option. In parallel, oncolytic viruses have been shown to be safe in patients. To prolong immune stimulation and to increase efficacy, these two fields are now merging and oncolytic viruses are armed with immunostimulatory transgenes. These novel agents are racing towards approval as established cancer immunotherapeutics.

Oncolytic adenoviruses coated with MHC-I tumor epitopes increase the antitumor immunity and efficacy against melanoma

The stimulation of the immune system using oncolytic adenoviruses (OAds) has attracted significant interest and several studies suggested that OAds immunogenicity might be important for their efficacy. Therefore, we developed a versatile and rapid system to adsorb tumor-specific major histocompatibility complex class I (MHC-I) peptides onto the viral surface to drive the immune response toward the tumor epitopes. By studying the model epitope SIINFEKL, we demonstrated that the peptide-coated OAd (PeptiCRAd) retains its infectivity and the cross presentation of the modified-exogenous epitope on MHC-I is not hindered. We then showed that the SIINFEKL-targeting PeptiCRAd achieves a superior antitumor efficacy and increases the percentage of antitumor CD8⁺ T cells and mature epitope-specific dendritic cells in vivo. PeptiCRAds loaded with clinically relevant tumor epitopes derived from tyrosinase-related protein 2 (TRP-2) and human gp100 could reduce the growth of primary-treated tumors and secondary-untreated melanomas, promoting the expansion of antigen-specific T-cell populations. Finally, we tested PeptiCRAd in humanized mice bearing human melanomas. In this model, a PeptiCRAd targeting the human melanoma-associated antigen A1 (MAGE-A1) and expressing granulocyte and macrophage colony-stimulating factor (GM-CSF) was able to eradicate established tumors and increased the human MAGE-A1-specific CD8⁺ T cell population. Herein, we show that the immunogenicity of OAds plays a key role in their efficacy and it can be exploited to direct the immune response system toward exogenous tumor epitopes. This versatile and rapid system overcomes the immunodominance of the virus and elicits a tumor-specific immune response, making PeptiCRAd a promising approach for clinical testing.

Intratumoral injection of Ad-ISF35 (Chimeric CD154) breaks tolerance and induces lymphoma tumor regression

Ad-ISF35, an adenovirus vector encoding a membrane-bound engineered CD154 chimeric protein (ISF35), induces complete A20 lymphoma tumor regression in mice after intratumoral direct injection (IDI). Ad-ISF35 induced durable local and systemic antitumor responses associated with a rapid tumor infiltration of macrophages and neutrophils as well as increased levels of proinflammatory cytokines in the tumor microenvironment. Ad-ISF35 IDI transduced preferentially fibroblasts and macrophages present in the tumor microenvironment, and ISF35 protein expression was observed in only 0.25% of cells present in the tumor. Moreover, Ad-ISF35 IDI induced upregulation of CD40 in tumor and immune regulatory cells, including those that did not express ISF35, suggesting the presence of a strong bystander effect. These responses resulted in the generation of IFN-γ-secreting cytotoxic lymphocytes and the production of specific cytotoxic antibodies against lymphoma cells. Overall, cellular immune therapy based on ISF35 induced phenotypic changes in the tumor cells and tumor microenvironment that were associated with a break in tumor immune tolerance and a curative antitumor effect in this lymphoma mouse model. Our data highlight the potential activity that modulation of costimulatory signaling has in cancer therapy.

Systemic Agonistic Anti-CD40 Treatment of Tumor-Bearing Mice Modulates Hepatic Myeloid-Suppressive Cells and Causes Immune-Mediated Liver Damage

Immune-stimulatory mAbs are currently being evaluated as antitumor agents. Although overall toxicity from these agents appears to be moderate, liver toxicities have been reported and are not completely understood. We studied the effect of systemic CD40 antibody treatment on myeloid cells in the spleen and liver. Naïve and tumor-bearing mice were treated systemically with agonistic anti-CD40 antibody. Immune cell subsets in the liver and spleen, serum transaminases, and liver histologies were analyzed after antibody administration. Nox2(-/-), Cd40(-/-), and bone marrow chimeric mice were used to study the mechanism by which agonistic anti-CD40 mediates its effects in vivo. Suppressor function of murine and human tumor-induced myeloid-derived suppressor cells (MDSC) was studied upon CD40 ligation. Agonistic CD40 antibody caused liver damage within 24 hours after injection in two unrelated tumor models and mice strains. Using bone marrow chimeras, we demonstrate that CD40 antibody-induced hepatitis in tumor-bearing mice was dependent on the presence of CD40-expressing hematopoietic cells. Agonistic CD40 ligation-dependent liver damage was induced by the generation of reactive oxygen species. Furthermore, agonistic CD40 antibody resulted in increased CD80-positive and CD40-positive liver CD11b(+)Gr-1(+) immature myeloid cells. CD40 ligation on tumor-induced murine and human CD14(+)HLA-DR(low) peripheral blood mononuclear cells from patients with cancer reduced their immune suppressor function. Collectively, agonistic CD40 antibody treatment activated tumor-induced myeloid cells, caused myeloid-dependent hepatotoxicity, and ameliorated the suppressor function of murine and human MDSC. Collectively, our data suggest that CD40 may mature immunosuppressive myeloid cells and thereby cause liver damage in mice with an accumulation of tumor-induced hepatic MDSC.