Local CTLA4 blockade effectively restrains experimental pancreatic adenocarcinoma growth in vivo

Enhancing pancreatic cancer immunotherapy: Leveraging localized delivery strategies through the use of implantable devices and scaffolds

Pancreatic cancer (PC) remains the predominant type of upper gastrointestinal tract cancer, associated with heightened morbidity and a survival rate below 12%. While immunotherapy has brought about transformative changes in the standards of care for most solid tumors, its application in PC is hindered by the ''cold tumor'' microenvironment, marked by the presence of immunosuppressive cells. Modest response rates in PC are attributed, in part to, the fibrotic stroma that obstructs the delivery of systemic immunotherapy. Furthermore, the occurrence of immune-related adverse events (iRAEs) often necessitates the use of sub-therapeutic doses or treatment discontinuation. In the pursuit of innovative approaches to enhance the effectiveness of immunotherapy for PC, implantable drug delivery devices and scaffolds emerge as promising strategies. These technologies offer the potential for sustained drug delivery directly to the tumor site, overcoming stromal barriers, immunosuppression, T cell exclusion, immunotherapy resistance, optimizing drug dosage, and mitigating systemic toxicity. This review offers a comprehensive exploration of pancreatic ductal adenocarcinoma (PDAC), the most common and aggressive form of PC, accompanied by a critical analysis of the challenges the microenvironment presents to the development of successful combinational immunotherapy approaches. Despite efforts, these approaches have thus far fallen short in enhancing treatment outcomes for PDAC. The review will subsequently delve into the imperative need for refining delivery strategies, providing an examination of past and ongoing studies in the field of localized immunotherapy for PDAC. Addressing these issues will lay the groundwork for the development of effective new therapies, thereby enhancing treatment response, patient survival, and overall quality of life for individuals diagnosed with PDAC.

Intratumoural immunotherapy plus focal thermal ablation for localized prostate cancer

Major advances have been made in the use of immunotherapy for the treatment of solid tumours, including the use of intratumourally injected immunotherapy instead of systemically delivered immunotherapy. The success of immunotherapy in prostate cancer treatment has been limited to specific populations with advanced disease, which is thought to be a result of prostate cancer being an immunologically 'cold' cancer. Accordingly, combining intratumoural immunotherapy with other treatments that would increase the immunological heat of prostate cancer is of interest. Thermal ablation therapy is currently one of the main strategies used for the treatment of localized prostate cancer and it causes immunological activation against prostate tissue. The use of intratumoural immunotherapy as an adjunct to thermal ablation offers the potential to elicit a systemic and lasting adaptive immune response to cancer-specific antigens, leading to a synergistic effect of combination therapy. The combination of thermal ablation and immunotherapy is currently in the early stages of investigation for the treatment of multiple solid tumour types, and the potential for this combination therapy to also offer benefit to prostate cancer patients is exciting.

Direct Functionalization of Polysaccharide-Based Xylan Phenyl Carbonate Nanoparticles with Tumor Cell Specific Antibodies

An efficient and easy-to-use approach is presented for obtaining biocompatible polysaccharide-based nanoparticles (NP) that can act as tumor-specific drug delivery agents. Two antibodies are directly immobilized onto reactive xylan phenyl carbonate (XPC) NP; namely Cetuximab (CTX) that binds to human epidermal growth factor receptor (EGFR) and Atezolizumab (ATZ) that binds to programmed death-ligand 1 (PD-L1). High coupling efficiency (up to 100 %) are achieved without any pre-activation and no aggregation occurs during antibody immobilization. By quartz crystal microbalance experiments with dissipation monitoring (QCM-D), flow cytometry assays, and confocal laser scanning microscopy imaging it is demonstrated that the functionalized XPC-NP specifically bind to cells carrying the corresponding antigens. Moreover, the NP retain the antibody specific bioactivities (growth inhibition for CTX and induction of T-cell cytotoxicity for ATZ).

Targeting post-translational modifications of Foxp3: a new paradigm for regulatory T cell-specific therapy

A healthy immune system is pivotal for the hosts to resist external pathogens and maintain homeostasis; however, the immunosuppressive tumor microenvironment (TME) damages the anti-tumor immunity and promotes tumor progression, invasion, and metastasis. Recently, many studies have found that Foxp3+ regulatory T (Treg) cells are the major immunosuppressive cells that facilitate the formation of TME by promoting the development of various tumor-associated cells and suppressing the activity of effector immune cells. Considering the role of Tregs in tumor progression, it is pivotal to identify new therapeutic drugs to target and deplete Tregs in tumors. Although several studies have developed strategies for targeted deletion of Treg to reduce the TME and support the accumulation of effector T cells in tumors, Treg-targeted therapy systematically affects the Treg population and may lead to the progression of autoimmune diseases. It has been understood that, nevertheless, in disease conditions, Foxp3 undergoes several definite post-translational modifications (PTMs), including acetylation, glycosylation, phosphorylation, ubiquitylation, and methylation. These PTMs not only elevate or mitigate the transcriptional activity of Foxp3 but also affect the stability and immunosuppressive function of Tregs. Various studies have shown that pharmacological targeting of enzymes involved in PTMs can significantly influence the PTMs of Foxp3; thus, it may influence the progression of cancers and/or autoimmune diseases. Overall, this review will help researchers to understand the advances in the immune-suppressive mechanisms of Tregs, the post-translational regulations of Foxp3, and the potential therapeutic targets and strategies to target the Tregs in TME to improve anti-tumor immunity.

Oncolytic viruses and antibodies: are they more successful when delivered separately or when engineered as a single agent?

Oncolytic viruses (OVs) provide the promise of tumor-selective cytotoxicity coupled with amplification of the therapeutic agent (the virus) in situ within the tumor improving its therapeutic index. Despite this promise, however, single agent-treatments have not been as successful as combination therapies, particularly combining with checkpoint inhibitor antibodies. The antibodies may be delivered by two approaches, either encoded within the OV genome to restrict antibody production to sites of active virus infection or alternatively given alongside OVs as separate treatments. Both approaches have shown promising therapeutic outcomes, and this leads to an interesting question of whether one approach is potentially better than the other. In this review, we provide a brief summary of the combination OV-antibody therapies that target tumor cells, tumor microenvironment and immune cells to help define key parameters influencing which approach is superior, thereby improving insight into the rational design of OV treatment strategies.

The pharmacotherapeutic management of nail unit and acral melanomas

INTRODUCTION

Acral and nail unit melanomas are rare subtypes of melanoma, which have poor prognoses. Current guidelines for optimal treatment are lacking. Recent clinical trials have evaluated new pharmacotherapeutic agents for melanoma treatment, with dramatically improved survival rates; however, studies on acral and nail unit melanomas are limited in comparison to trials on cutaneous melanoma.

AREAS COVERED

This is a comprehensive review of the literature regarding the available treatment options for acral and nail unit melanomas, with consideration of safety and tolerability.

EXPERT OPINION

Programmed cell death protein 1 inhibitors are more efficacious than cytotoxic T lymphocyte-associated antigen-4 blockers in acral and nail unit melanomas, although both are well-tolerated. Tyrosine kinase inhibitors have good clinical activity, however, data on safety is relatively limited. There is minimal data on high dose interferon α-2b and cyclin-dependent kinase 4 and 6 inhibitors, and efficacy and safety must be evaluated in future trials before they can be recommended for use in this patient population. Prospective clinical trials on acral and nail unit melanomas are lacking, and must be performed in large patient populations, with international collaboration likely necessary in order to enroll adequate participants.

An immune-related gene prognostic risk index for pancreatic adenocarcinoma

Objective

Our goal is to construct an immune-related gene prognostic risk index (IRGPRI) for pancreatic adenocarcinoma (PAAD), and to clarify the immune and molecular features in IRGPRI-defined PAAD subgroups and the benefit of immune checkpoint inhibitors (ICIs) therapy.

Method

Through differential gene expression analysis, weighted gene co-expression network analysis (WGCNA), and univariate Cox regression analysis, 16 immune-related hub genes were identified using the Cancer Genome Atlas (TCGA) PAAD dataset (n = 182) and immune gene set. From these genes, we constructed an IRGPRI with the Cox regression method and the IRGPRI was verified based on the Gene Expression Omnibus (GEO) dataset (n = 45). Then, we analyzed the immune and molecular features and the benefit of ICI therapy in IRGPRI-defined subgroups.

Results

Five genes, including S100A16, CD40, VCAM1, TNFRSF4 and TRAF1 were used to construct IRGPRI. As with the results of the GEO cohort, the overall survival (OS) was more favorable in low IRGPRI patients versus high IRGPRI patients. The composite results pointed out that low IRGPRI was associated with immune response-related pathways, high level of CTLA4, low KRAS and TP53 mutation rate, more infiltration of activated memory CD4⁺ T cells, CD8⁺ T cells, and more benefits from ICIs therapy. In comparison, high IRGPRI was associated with cancer-related pathways, low expression of CTLA4, high KRAS and TP53 mutation rate, more infiltration of M2 macrophages, and less benefit from ICIs therapies.

Conclusion

This IRGPRI is an encouraging biomarker to define the prognosis, immune and molecular features, and benefits from ICIs treatments in PAAD.

Synergistic anti-tumor efficacy of a hollow mesoporous silica-based cancer vaccine and an immune checkpoint inhibitor at the local site

Immune checkpoint inhibitors elicit durable tumor regression in multiple types of tumor, but may induce potential side effects with low response rates in many tumors. Herein, to increase the therapeutic efficacy of immune checkpoint inhibitors, a hollow mesoporous silica (HMS) nanosphere-based cancer vaccine was combined with an immune checkpoint inhibitor, anti-programmed death-ligand 1 (anti-PD-L1) antibody. The HMS nanospheres function as adjuvants that promote dendritic cell activation and antigen cross-presentation. Mice immunized with the HMS-based cancer vaccine show suppressed tumor growth with increased tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-2 (IL-2) levels in their spleens compared with those without HMS-based cancer vaccine. Moreover, the HMS-based cancer vaccine synergistically acts with the anti-PD-L1 antibody on the tumor. The combination of an HMS-based cancer vaccine and an antibody markedly decreases the required dose of the immune checkpoint inhibitor. Mice locally administered with the HMS-based cancer vaccine and 1/8 dose of a standard anti-PD-L1 antibody (25 µg/mouse) show comparable anti-tumor effect and significantly increased CD4⁺ and CD8⁺ T cell populations, compared with those systemically immunized with the standard anti-PD-L1 antibody done at 200 µg/mouse. Our work presents a promising cancer treatment strategy of combining an immune checkpoint inhibitor with an HMS-based cancer vaccine. STATEMENT OF SIGNIFICANCE: The clinical benefits of checkpoint blockade therapy rekindle the hope of cancer immunotherapy. However, objective response rates in checkpoint blockade therapy remain at about 10-40% owing to multiple immunosuppressive factors. To solve these problems, herein, a hollow mesoporous silica (HMS) nanosphere-based cancer vaccine was combined with an immune checkpoint inhibitor, anti-PD-L1 antibody. The HMS-based cancer vaccine synergistically acts with the anti-PD-L1 antibody on the tumor. Mice locally administered with the HMS-based cancer vaccine and 1/8 dose of a standard anti-PD-L1 antibody (25 µg/mouse) show comparable anti-tumor effect and significantly increased CD4⁺ and CD8⁺ T cell populations, compared with those systemically immunized with the standard anti-PD-L1 antibody done at 200 µg/mouse. Our work presents a promising cancer treatment strategy of combining an immune checkpoint inhibitor with an HMS-based cancer vaccine.

Pivotal antitumor role of the immune checkpoint molecule B7-H1 in pancreatic cancer

Immune checkpoint molecule B7-H1 plays a decisive immune regulatory role in different pathologies including cancer, and manipulation of B7-H1 expression became an attractive approach in cancer immunotherapy. Pancreatic cancer (PDAC) is characterized by pronounced immunosuppressive environment and B7-H1 expression correlates with PDAC prognosis. However, the first attempts to diminish B7-H1 expression in patients were not so successful. This points the complicity of PDAC immunosuppressive network and requires further examinations. We investigated the effect of B7-H1 deficiency in PDAC. Our results clearly show that partial or complete B7-H1 inhibition in vivo let to reduced tumor volume and improved survival of PDAC-bearing mice. This oncological benefit is due to the abrogation of immunosuppression provided by MDSC, macrophages, DC and Treg, which resulted in simultaneous restoration of anti-tumor immune response, namely improved accumulation and functionality of effector-memory CD4 and CD8 T cells. Our results underline the potential of B7-H1 molecule to control immunosuppressive network in PDAC and provide new issues for further clinical investigations.

Viro-antibody therapy: engineering oncolytic viruses for genetic delivery of diverse antibody-based biotherapeutics

Cancer therapeutics approved for clinical application include oncolytic viruses and antibodies, which evolved by nature, but were improved by molecular engineering. Both facilitate outstanding tumor selectivity and pleiotropic activities, but also face challenges, such as tumor heterogeneity and limited tumor penetration. An innovative strategy to address these challenges combines both agents in a single, multitasking therapeutic, i.e., an oncolytic virus engineered to express therapeutic antibodies. Such viro-antibody therapies genetically deliver antibodies to tumors from amplified virus genomes, thereby complementing viral oncolysis with antibody-defined therapeutic action. Here, we review the strategies of viro-antibody therapy that have been pursued exploiting diverse virus platforms, antibody formats, and antibody-mediated modes of action. We provide a comprehensive overview of reported antibody-encoding oncolytic viruses and highlight the achievements of 13 years of viro-antibody research. It has been shown that functional therapeutic antibodies of different formats can be expressed in and released from cancer cells infected with different oncolytic viruses. Virus-encoded antibodies have implemented direct tumor cell killing, anti-angiogenesis, or activation of adaptive immune responses to kill tumor cells, tumor stroma cells or inhibitory immune cells. Importantly, numerous reports have shown therapeutic activity complementary to viral oncolysis for these modalities. Also, challenges for future research have been revealed. Established engineering technologies for both oncolytic viruses and antibodies will enable researchers to address these challenges, facilitating the development of effective viro-antibody therapeutics.

Current strategies for intratumoural immunotherapy - Beyond immune checkpoint inhibition

Immunotherapy has revolutionised cancer treatment through restoration of host antitumour immune response. Immune checkpoint inhibitors (ICIs) confer durable responses in only a subset of patients. Mechanisms of ICI resistance to improve durable response rates and overall survival are an area of intense clinical research. Robust clinical development is ongoing to evaluate novel combination therapies to overcome ICI resistance, including targeting immunoregulatory pathways in the tumour microenvironment. Intratumoural (IT) immunotherapies such as toll-like receptor agonists, stimulator of interferon-induced gene agonists, retinoic-inducible gene I-like receptor agonists and oncolytic viruses may represent potential combination treatment options to overcome ICI resistance. Use of IT immunotherapies in combination with ICIs may alter the tumour microenvironment to address resistance mechanisms and improve antitumour response. Optimisation of IT immunotherapy clinical trials will elucidate resistance mechanisms, facilitate clinical trial design, define pharmacodynamic predictors that identify patients who may most benefit and inform clinical development of combination immunotherapy regimens. Here we provide an overview of IT immunotherapy principles, mechanisms of action, categories of IT immunotherapeutics, emerging data, clinical development strategies, response assessment, dose and schedule determination, clinical trial design and translational study design.

Intratumoural administration and tumour tissue targeting of cancer immunotherapies

Immune-checkpoint inhibitors and chimeric antigen receptor (CAR) T cells are revolutionizing oncology and haematology practice. With these and other immunotherapies, however, systemic biodistribution raises safety issues, potentially requiring the use of suboptimal doses or even precluding their clinical development. Delivering or attracting immune cells or immunomodulatory factors directly to the tumour and/or draining lymph nodes might overcome these problems. Hence, intratumoural delivery and tumour tissue-targeted compounds are attractive options to increase the in situ bioavailability and, thus, the efficacy of immunotherapies. In mouse models, intratumoural administration of immunostimulatory monoclonal antibodies, pattern recognition receptor agonists, genetically engineered viruses, bacteria, cytokines or immune cells can exert powerful effects not only against the injected tumours but also often against uninjected lesions (abscopal or anenestic effects). Alternatively, or additionally, biotechnology strategies are being used to achieve higher functional concentrations of immune mediators in tumour tissues, either by targeting locally overexpressed moieties or engineering 'unmaskable' agents to be activated by elements enriched within tumour tissues. Clinical trials evaluating these strategies are ongoing, but their development faces issues relating to the administration methodology, pharmacokinetic parameters, pharmacodynamic end points, and immunobiological and clinical response assessments. Herein, we discuss these approaches in the context of their historical development and describe the current landscape of intratumoural or tumour tissue-targeted immunotherapies.

Immune Checkpoint Therapy: Tumor Draining Lymph Nodes in the Spotlights

Tumor-draining lymph nodes play a paradoxical role in cancer. Surgeons often resect these sentinel lymph nodes to determine metastatic spread, thereby enabling prognosis and treatment. However, lymph nodes are vital organs for the orchestration of immune responses, due to the close encounters of dedicated immune cells. In view of the success of immunotherapy, the removal of tumor-draining lymph nodes needs to be re-evaluated and viewed in a different light. Recently, an important role for tumor-draining lymph nodes has been proposed in the immunotherapy of cancer. This new insight can change the use of immune checkpoint therapy, particularly with respect to the use in neoadjuvant settings in which lymph nodes are still operational.

Pickering emulsions with ethiodized oil and nanoparticles for slow release of intratumoral anti-CTLA4 immune checkpoint antibodies

BACKGROUND

Intratumorous immunotherapy for cancer is currently thriving. The aim of such local strategy is to improve the therapeutic index of these treatments, for higher on-target/on-tumor activity and less on-target/off-tumor adverse events. Strategies allowing for slow release of anti-CTLA4 in the tumor microenvironment could improve their clinical efficacy.The purpose of the study was to develop a radiopaque delivery platform to improve the targeting and exposure of intratumorous anti-CTLA4 antibodies for cancer immunotherapy.

METHODS

Pickering emulsions of anti-CTLA4 antibodies were formulated with radiopaque ethiodized oil and poly-lactic-co-glycolic acid (PLGA) nanoparticles. We characterized the microscopic aspect and stability of such emulsions using Turbiscan. We monitored the release of anti-CTLA4 over time from these emulsions and evaluated their structure using mass spectrometry. We then tested the functionality of the released antibodies by preforming ex vivo competitive binding assays. Finally, we assessed the in vivo efficacy of intratumorous anti-CTLA4 Pickering emulsions.

RESULTS

Pickering emulsions of ethiodized oil and PLGA nanoparticles (PEEPs) resulted in a radiopaque water-in-oil emulsion with average internal phase droplet size of 42±5 µm at day 7. Confocal microscopy showed that anti-CTLA4 antibodies were effectively encapsulated by ethiodized oil with PLGA nanoparticles located at the interface between the aqueous and the oily phase. Turbiscan analysis showed that emulsions were stable with continuous and progressive release of anti-CTLA4 antibodies reaching 70% at 3 weeks. Structural and functional analysis of the released antibodies did not show significant differences with native anti-CTLA4 antibodies. Finally, intratumorous anti-CTLA4 PEEPs were able to eradicate tumors and cure mice in a syngeneic immunocompetent preclinical tumor model.

CONCLUSION

Pickering emulsions of ethiodized oil and PLGA is an innovative radiopaque delivery platform that does not alter the functionality of anti-CTLA4 immune checkpoint antibodies. Beyond local anti-CTLA4 applications, these emulsions might be used with other therapeutic molecules for optimal intratumorous or intra-arterial delivery of novel cancer immunotherapies.

Modulation of the immune microenvironment of high-risk ductal carcinoma in situ by intralesional pembrolizumab injection

Ductal carcinoma in situ (DCIS) is a risk factor for the subsequent development of invasive breast cancer. High-risk features include age <45 years, size >5 cm, high-grade, palpable mass, hormone receptor negativity, and HER2 positivity. We have previously shown that immune infiltrates are positively associated with these high-risk features, suggesting that manipulating the immune microenvironment in high-risk DCIS could potentially alter disease progression. Patients with high-risk DCIS were enrolled in this 3 × 3 phase 1 dose-escalation pilot study of 2, 4, and 8 mg intralesional injections of the PD-1 immune checkpoint inhibitor, pembrolizumab. Study participants received two intralesional injections, three weeks apart, prior to surgery. Tissue from pre-treatment biopsies and post-treatment surgical resections was analyzed using multiplex immunofluorescence (mIF) staining for various immune cell populations. The intralesional injections were easily administered and well-tolerated. mIF analyses demonstrated significant increases in total T cell and CD8+ T cell percentages in most patients after receiving pembrolizumab, even at the 2 mg dose. T cell expansion was confined primarily to the stroma rather than within DCIS-containing ducts. Neither cleaved caspase 3 (CC3) staining, a marker for apoptosis, nor DCIS volume (as measured by MRI) changed significantly following treatment. Intralesional injection of pembrolizumab is safe and feasible in patients with DCIS. Nearly all patients experienced robust total and CD8+ T cell responses. However, we did not observe evidence of cell death or tumor volume decrease by MRI, suggesting that additional strategies may be needed to elicit stronger anti-tumor immunity.

Antibody therapy in pancreatic cancer: mAb-ye we're onto something?

Pancreatic cancer remains an extremely deadly disease, with little improvement seen in treatment or outcomes over the last 40 years. Targeted monoclonal antibody therapy is one area that has been explored in attempts to tackle this disease. This review examines antibodies that have undergone clinical evaluation in pancreatic cancer. These antibodies target a wide variety of molecules, including tumour cell surface, stromal, immune and embryonic pathway targets. We discuss the therapeutic utility of these therapies both as monotherapeutics and in combination with other treatments such as chemotherapy. While antibody therapy for pancreatic cancer has yet to yield significant success, lessons learned from research thus far highlights future directions that may help overcome observed hurdles to yield clinically efficacious results.

Locally Advanced Pancreatic Cancer: Percutaneous Management Using Ablation, Brachytherapy, Intra-arterial Chemotherapy, and Intra-tumoral Immunotherapy

PURPOSE OF REVIEW

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive neoplasms, bearing a terrible prognosis. Stage III tumors, also known as locally advanced pancreatic cancer (LAPC), are unresectable, and current palliative chemotherapy regimens have only modestly improved survival in these patients. At this stage of disease, interventional techniques may be of value and further prolong life. The aim of this review was to explore current literature on locoregional percutaneous management for LAPC.

RECENT FINDINGS

Locoregional percutaneous interventional techniques such as ablation, brachytherapy, and intra-arterial chemotherapy possess cytoreductive abilities and have the potential to increase survival. In addition, recent research demonstrates the immunomodulatory capacities of these treatments. This immune response may be leveraged by combining the interventional techniques with intra-tumoral immunotherapy, possibly creating a durable anti-tumor effect. This multimodality treatment approach is currently being examined in several ongoing clinical trials. The use of certain interventional techniques appears to improve survival in LAPC patients and may work synergistically when combined with immunotherapy. However, definitive conclusions can only be made when large prospective (randomized controlled) trials confirm these results.

Emerging antibody therapies for pancreatic adenocarcinoma: a review of recent phase 2 trials

Introduction: Pancreatic adenocarcinoma is now the third-leading cause of cancer-related deaths in the US which can be attributed to rising incidence, diagnosis at advanced stages and early development of metastasis. Systemic therapy remains palliative with early development of resistance possibly related to the constitutive activation of 'undruggable' KRAS, immunosuppressive microenvironment, and intense desmoplasia. The advancements in molecular biology has led to the development and investigation of targeted and immune therapeutics.Areas covered: This study provides a comprehensive review of the literature to further the understanding of molecular targets with their respective antibody-based therapies in clinical development in pancreatic cancer. PubMed was systematically searched for English-language articles discussing antibody-based therapies under phase 2 clinical trial investigation in pancreatic adenocarcinoma.Expert opinion: PDAC remains highly resistant to chemotherapy with no significant improvement in survival for patients with advanced or metastatic cancer. Unfortunately, the majority of the antibody-based targeted and immune therapeutics have failed to meet their primary efficacy endpoints in early phase trials. However, there are a few promising antibody-based drugs with intriguing preliminary data that merit further investigation, while many more continue to be developed and investigated preclinically, and in early phase trials.

CTLA-4 in Regulatory T Cells for Cancer Immunotherapy

Immune checkpoint inhibitors (ICIs) have obtained durable responses in many cancers, making it possible to foresee their potential in improving the health of cancer patients. However, immunotherapies are currently limited to a minority of patients and there is a need to develop a better understanding of the basic molecular mechanisms and functions of pivotal immune regulatory molecules. Immune checkpoint cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and regulatory T (Treg) cells play pivotal roles in hindering the anticancer immunity. Treg cells suppress antigen-presenting cells (APCs) by depleting immune stimulating cytokines, producing immunosuppressive cytokines and constitutively expressing CTLA-4. CTLA-4 molecules bind to CD80 and CD86 with a higher affinity than CD28 and act as competitive inhibitors of CD28 in APCs. The purpose of this review is to summarize state-of-the-art understanding of the molecular mechanisms underlining CTLA-4 immune regulation and the correlation of the ICI response with CTLA-4 expression in Treg cells from preclinical and clinical studies for possibly improving CTLA-4-based immunotherapies, while highlighting the knowledge gap.

UXT antisense RNA 1 sever as a novel prognostic long non-coding RNA in early stage pancreatic ductal adenocarcinoma patients after receiving pancreaticoduodenectomy

Objective: The principal objective of this project was to investigate the prognostic value of UXT antisense RNA 1 (UXT-AS1) in pancreatic ductal adenocarcinoma (PDAC), as well as its biological function mechanisms and the screening of targeted drugs using The Cancer Genome Atlas (TCGA) PDAC genome-wide RNA sequencing (RNA-seq) dataset.

Methods: We used TCGA 112 early stage PDAC patients to screen the prognostic value of UXT-AS1. Biological functions and mechanisms of UXT-AS1 were investigated by co-expression analysis, differentially expressed genes (DEGs) and gene set enrichment analysis, while targeted drug screening was investigated by connectivity Map (CMap).

Results: By analyzing the dataset from TCGA cohort, we found that UXT-AS1 was significantly up-regulated in pancreatic cancer tissues. Multivariate survival analysis demonstrated that PDAC patients with high UXT-AS1 expression had an unfavourable prognosis (adjusted P=0.033, HR=1.830, 95%CI=1.051-3.188). Genome-wide co-expression analysis and gene set enrichment analysis suggested that UXT-AS1 may act as a pivotal part in PDAC by participating in nuclear factor kappa beta, regulation of tumor necrosis factor, cell adhesion, T cell receptor signaling pathway, and numerous immune-related biological processes and signaling pathways. Functional enrichment analysis of DEGs between high- and low-UXT-AS1 expression groups suggested that these DEGs were significant enriched in B cell receptor complex, response to drug chemical carcinogenesis and drug metabolism-cytochrome P450. CMap analysis revealed that quipazine and terazosin may be targeted drugs for UXT-AS1 in PDAC.

Conclusion: Our current study has identified UXT-AS1 as a novel biomarker for the prognosis of early stage PDAC. We also clarified its biological functional mechanisms and identified two targeted drugs of UXT-AS1 in PDAC.

Preclinical Models of Pancreatic Ductal Adenocarcinoma and Their Utility in Immunotherapy Studies

Simple Summary

Immune checkpoint blockade has provided durable clinical responses in a number of human malignancies, but not in patients with pancreatic cancer. Efforts to understand mechanisms of resistance and increase efficacy of immune checkpoint blockade in pancreatic cancer require the use of appropriate preclinical models in the laboratory. Here, we discuss the benefits, caveats, and potentials for improvement of the most commonly used models, including murine-based and patient-derived models.

Abstract

The advent of immunotherapy has transformed the treatment landscape for several human malignancies. Antibodies against immune checkpoints, such as anti-PD-1/PD-L1 and anti-CTLA-4, demonstrate durable clinical benefits in several cancer types. However, checkpoint blockade has failed to elicit effective anti-tumor responses in pancreatic ductal adenocarcinoma (PDAC), which remains one of the most lethal malignancies with a dismal prognosis. As a result, there are significant efforts to identify novel immune-based combination regimens for PDAC, which are typically first tested in preclinical models. Here, we discuss the utility and limitations of syngeneic and genetically-engineered mouse models that are currently available for testing immunotherapy regimens. We also discuss patient-derived xenograft mouse models, human PDAC organoids, and ex vivo slice cultures of human PDAC tumors that can complement murine models for a more comprehensive approach to predict response and resistance to immunotherapy regimens.

Design and Efficacy of a Monovalent Bispecific PD-1/CTLA4 Antibody That Enhances CTLA4 Blockade on PD-1+ Activated T Cells

The clinical benefit of PD-1 blockade can be improved by combination with CTLA4 inhibition but is commensurate with significant immune-related adverse events suboptimally limiting the doses of anti-CTLA4 mAb that can be used. MEDI5752 is a monovalent bispecific antibody designed to suppress the PD-1 pathway and provide modulated CTLA4 inhibition favoring enhanced blockade on PD-1⁺ activated T cells. We show that MEDI5752 preferentially saturates CTLA4 on PD-1⁺ T cells versus PD-1^- T cells, reducing the dose required to elicit IL2 secretion. Unlike conventional PD-1/CTLA4 mAbs, MEDI5752 leads to the rapid internalization and degradation of PD-1. Moreover, we show that MEDI5752 preferentially localizes and accumulates in tumors providing enhanced activity when compared with a combination of mAbs targeting PD-1 and CTLA4 in vivo. Following treatment with MEDI5752, robust partial responses were observed in two patients with advanced solid tumors. MEDI5752 represents a novel immunotherapy engineered to preferentially inhibit CTLA4 on PD-1⁺ T cells. SIGNIFICANCE: The unique characteristics of MEDI5752 represent a novel immunotherapy engineered to direct CTLA4 inhibition to PD-1⁺ T cells with the potential for differentiated activity when compared with current conventional mAb combination strategies targeting PD-1 and CTLA4. This molecule therefore represents a step forward in the rational design of cancer immunotherapy.See related commentary by Burton and Tawbi, p. 1008.This article is highlighted in the In This Issue feature, p. 995.

RNA-electroporated T cells for cancer immunotherapy

Adoptive T cell therapy has proven effective against hematologic malignancies and demonstrated efficacy against a variety of solid tumors in preclinical studies and clinical trials. Nonetheless, antitumor responses against solid tumors remain modest, highlighting the need to enhance the effectiveness of this therapy. Genetic modification of T cells with RNA has been explored to enhance T-cell antigen specificity, effector function, and migration to tumor sites, thereby potentiating antitumor immunity. This review describes the rationale for RNA-electroporated T cell modifications and provides an overview of their applications in preclinical and clinical investigations for the treatment of hematologic malignancies and solid tumors.

Intratumoral Immunotherapy: From Trial Design to Clinical Practice

Systemic immunotherapies such as immune checkpoint blockade targeted at PD(L)1 and CTLA4 have demonstrated their ability to provide durable tumor responses and long-term overall survival benefits for some patients in several solid tumor types. However, a majority of patients remain resistant to these treatments and a significant proportion of them develop severe autoimmune and inflammatory adverse events. Preclinical studies have demonstrated that intratumoral injections of immunostimulatory products (oncolytics, pattern recognition receptor agonists,…) that are able to trigger type I IFN release and enhance tumor antigen presentation on immune cells could generate a strong antitumor immunity and overcome the resistance to systemic immune checkpoint blockade therapies. The intratumoral immunotherapy strategies that are currently in clinical development offer a unique therapeutic and exploratory setting to better understand the immune contexture across tumor lesions of patients with metastatic cancer. Also these local therapeutic products could turn cold tumors into hot and improve the response rates to cancer immunotherapies while diminishing their systemic exposure and toxicities. Intratumoral immunotherapies could prime or boost the immunity against tumors and therefore radically change the combinatorial therapeutic strategies currently pursued for metastatic and local cancers to improve their long-term survival. We aimed to review and discuss the scientific rationale for intratumoral immunotherapy, the challenges raised by this strategy in terms of drug development within clinical trials and the current state-of-the-art regarding the clinical practice of this innovative approach.

Advances in engineering local drug delivery systems for cancer immunotherapy

Cancer immunotherapy aims to leverage the immune system to suppress the growth of tumors and to inhibit metastasis. The recent promising clinical outcomes associated with cancer immunotherapy have prompted research and development efforts towards enhancing the efficacy of immune checkpoint blockade, cancer vaccines, cytokine therapy, and adoptive T cell therapy. Advancements in biomaterials, nanomedicine, and micro-/nano-technology have facilitated the development of enhanced local delivery systems for cancer immunotherapy, which can enhance treatment efficacy while minimizing toxicity. Furthermore, locally administered cancer therapies that combine immunotherapy with chemotherapy, radiotherapy, or phototherapy have the potential to achieve synergistic antitumor effects. Herein, the latest studies on local delivery systems for cancer immunotherapy are surveyed, with an emphasis on the therapeutic benefits associated with the design of biomaterials and nanomedicines. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Resistance to Checkpoint Inhibition in Cancer Immunotherapy

The interaction of the host immune system with tumor cells in the tissue microenvironment is essential in understanding tumor immunity and development of successful cancer immunotherapy. The presence of lymphocytes in tumors is highly correlated with an improved outcome. T cells have a set of cell surface receptors termed immune checkpoints that when activated suppress T cell function. Upregulation of immune checkpoint receptors such as programmed cell death 1 (PD-1) and cytotoxic T lymphocyte associated protein 4 (CTLA-4) occurs during T cell activation in an effort to prevent damage from an excessive immune response. Immune checkpoint inhibitors allow the adaptive immune system to respond to tumors more effectively. There has been clinical success in different types of cancer blocking immune checkpoint receptors such as PD-1 and CTLA. However, relapse has occurred. The innate and acquired/therapy induced resistance to treatment has been encountered. Aberrant cellular signal transduction is a major contributing factor to resistance to immunotherapy. Combination therapies with other co-inhibitory immune checkpoints such as TIM-3, LAG3 and VISTA are currently being tested to overcome resistance to cancer immunotherapy. Expression of TIM-3 has been associated with resistance to PD-1 blockade and combined blockade of TIM-3 and PD-1 has demonstrated improved responses in preclinical models. LAG3 blockade has the potential to increase the responsiveness of cytotoxic T-cells to tumors. Furthermore, tumors that were found to express VISTA had an increased rate of growth due to the T cell suppression. The growing understanding of the inhibitory immune checkpoints’ ligand biology, signaling mechanisms, and T-cell suppression in the tumor microenvironment continues to fuel preclinical and clinical advancements in design, testing, and approval of agents that block checkpoint molecules. Our review seeks to bridge fundamental regulatory mechanisms across inhibitory immune checkpoint receptors that are of great importance in resistance to cancer immunotherapy. We will summarize the biology of different checkpoint molecules, highlight the effect of individual checkpoint inhibition as anti-tumor therapies, and outline the literatures that explore mechanisms of resistance to individual checkpoint inhibition pathways.

Nanotopography-based lymphatic delivery for improved anti-tumor responses to checkpoint blockade immunotherapy

Rationale: Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) is a co-inhibitory checkpoint receptor that is expressed by naïve T-cells in lymph nodes (LNs) to inhibit activation against “self” antigens (Ags). In cancer, anti-CTLA-4 blocks inhibitory action, enabling robust activation of T-cells against tumor Ags presented in tumor draining LNs (TDLNs). However, anti-CTLA-4 is administered intravenously with limited exposure within TDLNs and immune related adverse events (irAEs) are associated with over-stimulation of the immune system.

Methods: Herein, we first deliver anti-CTLA-4 in an orthotopic mammary carcinoma murine model using a nanotopographical microneedle-array device to compare its anti-tumor response to that from systemic administration. Additionally, to demonstrate the feasibility of lymphatic delivery in humans using the device, we use near-infrared fluorescence imaging to image delivery of ICG to LNs.

Results: Our data show that lymphatic infusion results in more effective tumor growth inhibition, arrest of metastases, increased tumor infiltrating lymphocytes and complete responses when compared to conventional systemic administration. In clinical studies, we demonstrate for the first time that nanotopographic infusion can deliver ICG through the lymphatics directly to the axilla and inguinal LNs of healthy human volunteers.

Conclusion: Taken together, these results suggest that regional delivery using a nanotopography-based microneedle array could revolutionize checkpoint blockade immunotherapy by reducing systemic drug exposure and maximizing drug delivery to TDLNs where tumor Ags present. Future work is needed to determine whether lymphatic delivery of anti-CTLA-4 can alleviate irAEs that occur with systemic dosing.

A Neuropilin-1 Antagonist Exerts Antitumor Immunity by Inhibiting the Suppressive Function of Intratumoral Regulatory T Cells

Regulatory T cells (Treg) are targeted for cancer immunotherapy because they suppress antitumor immunity. Although the importance of neuropilin-1 (NRP1) in the stability and function of intratumoral Tregs is well-documented, targeting of NRP1⁺ Tregs for anticancer immunotherapy has not been well explored. Here, we found that an NRP1 antagonist [Fc(AAG)-TPP11], generated by fusion of the NRP1-specific binding peptide TPP11 with the C-terminus of an effector function-deficient immunoglobulin Fc(AAG) variant, inhibits intratumoral NRP1⁺ Treg function and stability. Fc(AAG)-TPP11 triggered the internalization of NRP1, reducing its surface expression on Tregs and thereby inhibiting the suppressive function of Tregs. In two murine syngeneic tumor models, Fc(AAG)-TPP11 retarded tumor growth, comparable with a Treg-depleting anti-CTLA-4 antibody, without noticeable toxicity. Fc(AAG)-TPP11 inhibited NRP1-dependent Treg function, inducing unstable intratumoral Tregs, with reduced expression of Foxp3 and enhanced production of IFNγ, which subsequently increased the functionality and frequency of intratumoral CD8⁺ T cells. We also observed selective expression of NRP1 on Tregs isolated from human tumors, but not from the blood of healthy donors and patients with cancer, as well as ex vivo inhibition of intratumoral NRP1⁺ Treg function by Fc(AAG)-TPP11. Our results suggest that the NRP1 antagonist Fc(AAG)-TPP11 has therapeutic potential for the inhibition of intratumoral NRP1⁺ Tregs with limited unfavorable effects on peripheral Tregs.

The CTLA-4 x OX40 bispecific antibody ATOR-1015 induces anti-tumor effects through tumor-directed immune activation

BACKGROUND

The CTLA-4 blocking antibody ipilimumab has demonstrated substantial and durable effects in patients with melanoma. While CTLA-4 therapy, both as monotherapy and in combination with PD-1 targeting therapies, has great potential in many indications, the toxicities of the current treatment regimens may limit their use. Thus, there is a medical need for new CTLA-4 targeting therapies with improved benefit-risk profile.

METHODS

ATOR-1015 is a human CTLA-4 x OX40 targeting IgG1 bispecific antibody generated by linking an optimized version of the Ig-like V-type domain of human CD86, a natural CTLA-4 ligand, to an agonistic OX40 antibody. In vitro evaluation of T-cell activation and T regulatory cell (Treg) depletion was performed using purified cells from healthy human donors or cell lines. In vivo anti-tumor responses were studied using human OX40 transgenic (knock-in) mice with established syngeneic tumors. Tumors and spleens from treated mice were analyzed for CD8+ T cell and Treg frequencies, T-cell activation markers and tumor localization using flow cytometry.

RESULTS

ATOR-1015 induces T-cell activation and Treg depletion in vitro. Treatment with ATOR-1015 reduces tumor growth and improves survival in several syngeneic tumor models, including bladder, colon and pancreas cancer models. It is further demonstrated that ATOR-1015 induces tumor-specific and long-term immunological memory and enhances the response to PD-1 inhibition. Moreover, ATOR-1015 localizes to the tumor area where it reduces the frequency of Tregs and increases the number and activation of CD8+ T cells.

CONCLUSIONS

By targeting CTLA-4 and OX40 simultaneously, ATOR-1015 is directed to the tumor area where it induces enhanced immune activation, and thus has the potential to be a next generation CTLA-4 targeting therapy with improved clinical efficacy and reduced toxicity. ATOR-1015 is also expected to act synergistically with anti-PD-1/PD-L1 therapy. The pre-clinical data support clinical development of ATOR-1015, and a first-in-human trial has started (NCT03782467).

Cancer DNA vaccines: current preclinical and clinical developments and future perspectives

The recent developments in immuno-oncology have opened an unprecedented avenue for the emergence of vaccine strategies. Therapeutic DNA cancer vaccines are now considered a very promising strategy to activate the immune system against cancer. In the past, several clinical trials using plasmid DNA vaccines demonstrated a good safety profile and the activation of a broad and specific immune response. However, these vaccines often demonstrated only modest therapeutic effects in clinical trials due to the immunosuppressive mechanisms developed by the tumor. To enhance the vaccine-induced immune response and the treatment efficacy, DNA vaccines could be improved by using two different strategies. The first is to increase their immunogenicity by selecting and optimizing the best antigen(s) to be inserted into the plasmid DNA. The second strategy is to combine DNA vaccines with other complementary therapies that could improve their activity by attenuating immunosuppression in the tumor microenvironment or by increasing the activity/number of immune cells. A growing number of preclinical and clinical studies are adopting these two strategies to better exploit the potential of DNA vaccination. In this review, we analyze the last 5-year preclinical studies and 10-year clinical trials using plasmid DNA vaccines for cancer therapy. We also investigate the strategies that are being developed to overcome the limitations in cancer DNA vaccination, revisiting the rationale for different combinations of therapy and the different possibilities in antigen choice. Finally, we highlight the most promising developments and critical points that need to be addressed to move towards the approval of therapeutic cancer DNA vaccines as part of the standard of cancer care in the future.

TAMing pancreatic cancer: combat with a double edged sword

Among all the deadly cancers, pancreatic cancer ranks seventh in mortality. The absence of any grave symptoms coupled with the unavailability of early prognostic and diagnostic markers make the disease incurable in most of the cases. This leads to a late diagnosis, where the disease would have aggravated and thus, incurable. Only around 20% of the cases present the early disease diagnosis. Surgical resection is the prime option available for curative local disease but in the case of advanced cancer, chemotherapy is the standard treatment modality although the patients end up with drug resistance and severe side effects. Desmoplasia plays a very important role in chemoresistance associated with pancreatic cancer and consists of a thick scar tissue around the tumor comprised of different cell populations. The interplay between this heterogenous population in the tumor microenvironment results in sustained tumor growth and metastasis. Accumulating evidences expose the crucial role played by the tumor-associated macrophages in pancreatic cancer and this review briefly presents the origin from their parent lineage and the importance in maintaining tumor hallmarks. Finally we have tried to address their role in imparting chemoresistance and the therapeutic interventions leading to reduced tumor burden.

A Recombinant Antibody-Expressing Influenza Virus Delays Tumor Growth in a Mouse Model

Influenza A virus (IAV) has shown promise as an oncolytic agent. To improve IAV as an oncolytic virus, we sought to design a transgenic virus expressing an immune checkpoint-inhibiting antibody during the viral life cycle. To test whether it was possible to express an antibody during infection, an influenza virus was constructed encoding the heavy chain of an antibody on the PB1 segment and the light chain of an antibody on the PA segment. This antibody-expressing IAV grows to high titers, and the antibodies secreted from infected cells exhibit comparable functionality with hybridoma-produced antibodies. To enhance the anti-cancer activity of IAV, an influenza virus was engineered to express a single-chain antibody antagonizing the immune checkpoint CTLA4 (IAV-CTLA4). In mice implanted with the aggressive B16-F10 melanoma, intratumoral injection with IAV-CTLA4 delayed the growth of treated tumors, mediated an abscopal effect, and increased overall survival.

Intrapleural immunotherapy: An update on emerging treatment strategies for pleural malignancy

OBJECTIVES

Malignant pleural mesothelioma and malignant pleural effusions are a major therapeutic challenge, and are associated with impairment in quality of life and increased mortality. Advances in systemic therapies of malignant pleural mesothelioma have demonstrated limited clinical benefit and there is ongoing interest in intrapleural immunotherapies which have been demonstrated to be well tolerated overall with variable clinical responses. We have reviewed the literature to provide a comprehensive summary of novel intrapleural immunotherapeutic paradigms, including oncolytic virus therapy, gene-mediated cytotoxic immunotherapy, direct cytokine-mediated immunotherapies, innate immunomodulators and adoptive transfer of intrapleural chimeric antigen receptor T-cell therapy.

DATA SOURCES

A review of PubMed for original manuscripts and conference reports published between 1998 and 2018 pertaining to intrapleural immunotherapy, as well as examination of reference lists from reviewed manuscripts.

STUDY SELECTION

Human clinical trials on intrapleural immunotherapies in subjects with malignant pleural mesothelioma or malignant pleural effusion were included in this review, including some relevant preclinical studies and anticipated ongoing trials reported on Clinicaltrials.gov.

RESULTS

Twenty-six clinical trials were identified, in addition to three trials currently in progress.

CONCLUSION

Intrapleural immunotherapies for pleural malignancy have demonstrated promise with regard to generating durable tumor-specific immune responses with possible clinical benefits which merit further investigation as part of multimodal chemotherapeutic and immunotherapeutic regimens.

Chimeric antigen receptor T cell therapy and other therapeutics for malignancies: Combination and opportunity

Chimeric antigen receptor T (CAR-T) cell therapy provides possibility for the treatment of malignancies since clinical trials have shown that CAR-T therapy has a significant anti-tumor effect. Although many efforts have been made to improve the efficacy and reduce the side effects of CAR-T therapy, there are still many problems to solve. With the rapid development of this field, combination immunotherapy has been proved to improve the efficacy of CAR-T therapy. Studies have shown that radiotherapy, chemotherapy, oncolytic virotherapy, BTK inhibitors and immune checkpoint blockade-based therapy may further enhance the efficacy of CAR-T therapy while CRISPR/Cas9 technology and IL-1 blockade may improve the safety. In this review, we summarized the advantages and the mechanisms of the combination immunotherapy based on CAR-T cell therapy.

A CD40 Agonist and PD-1 Antagonist Antibody Reprogram the Microenvironment of Nonimmunogenic Tumors to Allow T-cell-Mediated Anticancer Activity

In cancers with tumor-infiltrating lymphocytes (TILs), monoclonal antibodies (mAbs) that block immune checkpoints such as CTLA-4 and PD-1/PD-L1 promote antitumor T-cell immunity. Unfortunately, most cancers fail to respond to single-agent immunotherapies. T regulatory cells, myeloid derived suppressor cells (MDSCs), and extensive stromal networks within the tumor microenvironment (TME) dampen antitumor immune responses by preventing T-cell infiltration and/or activation. Few studies have explored combinations of immune-checkpoint antibodies that target multiple suppressive cell populations within the TME, and fewer have studied the combinations of both agonist and antagonist mAbs on changes within the TME. Here, we test the hypothesis that combining a T-cell-inducing vaccine with both a PD-1 antagonist and CD40 agonist mAbs (triple therapy) will induce T-cell priming and TIL activation in mouse models of nonimmunogenic solid malignancies. In an orthotopic breast cancer model and both subcutaneous and metastatic pancreatic cancer mouse models, only triple therapy was able to eradicate most tumors. The survival benefit was accompanied by significant tumor infiltration of IFNγ-, Granzyme B-, and TNFα-secreting effector T cells. Further characterization of immune populations was carried out by high-dimensional flow-cytometric clustering analysis and visualized by t-distributed stochastic neighbor embedding (t-SNE). Triple therapy also resulted in increased infiltration of dendritic cells, maturation of antigen-presenting cells, and a significant decrease in granulocytic MDSCs. These studies reveal that combination CD40 agonist and PD-1 antagonist mAbs reprogram immune resistant tumors in favor of antitumor immunity.

Tumor-conditional anti-CTLA4 uncouples antitumor efficacy from immunotherapy-related toxicity

While immune checkpoint blockade leads to potent antitumor efficacy, it also leads to immune-related adverse events in cancer patients. These toxicities stem from systemic immune activation resulting in inflammation of multiple organs, including the gastrointestinal tract, lung, and endocrine organs. We developed a dual variable domain immunoglobulin of anti-CTLA4 antibody (anti-CTLA4 DVD, where CTLA4 is defined as cytotoxic T lymphocyte-associated antigen-4) possessing an outer tumor-specific antigen-binding site engineered to shield the inner anti-CTLA4-binding domain. Upon reaching the tumor, the outer domain was cleaved by membrane type-serine protease 1 (MT-SP1) present in the tumor microenvironment, leading to enhanced localization of CTLA4 blockade. Anti-CTLA4 DVD markedly reduced multiorgan immune toxicity by preserving tissue-resident Tregs in Rag 1-/- mice that received naive donor CD4+ T cells from WT C57BL/6j mice. Moreover, anti-CTLA4 DVD induced potent antitumor effects by decreasing tumor-infiltrating Tregs and increasing the infiltration of antigen-specific CD8+ T lymphocytes in TRAMP-C2-bearing C57BL/6j mice. Treg depletion was mediated through the antibody-dependent cellular cytotoxicity (ADCC) mechanism, as anti-CTLA4 without the FcγR-binding portion (anti-CTLA4 DANA) spared Tregs, preventing treatment-induced toxicities. In summary, our results demonstrate an approach to anti-CTLA4 blockade that depletes tumor-infiltrating, but not tissue-resident, Tregs, preserving antitumor effects while minimizing toxicity. Thus, our tumor-conditional anti-CTLA4 DVD provides an avenue for uncoupling antitumor efficacy from immunotherapy-induced toxicities.

New opportunities for nanoparticles in cancer immunotherapy

BACKGROUND

Recently, cancer immunotherapy has become standard for cancer treatment. Immunotherapy not only treats primary tumors, but also prevents metastasis and recurrence, representing a major advantage over conventional cancer treatments. However, existing cancer immunotherapies have limited clinical benefits because cancer antigens are often not effectively delivered to immune cells. Furthermore, unlike lymphoma, solid tumors evade anti-cancer immunity by forming an immune-suppressive tumor microenvironment (TME). One approach for overcoming these limitations of cancer immunotherapy involves nanoparticles based on biomaterials.

MAIN BODY

Here, we review in detail recent trends in the use of nanoparticles in cancer immunotherapy. First, to illustrate the unmet needs for nanoparticles in this field, we describe the mechanisms underlying cancer immunotherapy. We then explain the role of nanoparticles in the delivery of cancer antigens and adjuvants. Next, we discuss how nanoparticles can be helpful within the immune-suppressive TME. Finally, we summarize current and future uses of nanoparticles with image-guided interventional techniques in cancer immunotherapy.

CONCLUSION

Recently developed approaches for using nanoparticles in cancer immunotherapy have enormous potential for improving cancer treatment. Cancer immunotherapy based on nanoparticles is anticipated not only to overcome the limitations of existing immunotherapy, but also to generate synergistic effects via cooperation between nanoparticles and immune cells.

Chimeric antigen receptor T cell therapy in pancreatic cancer: from research to practice

Chimeric antigen receptor (CAR) T cell therapy is genetically engineered tumor antigen-specific anticancer immunotherapy, which after showing great success in hematological malignancies is currently being tried in advanced solid tumors like pancreatic cancer. Immunosuppressive tumor microenvironment and dense fibrous stroma are some of the limitation in the success of this novel therapy. However, genetic modifications and combination therapy is the topic of the research to improve its efficacy. In this article, we summarize the current state of knowledge, limitations, and future prospects for CAR T cell therapy in pancreatic cancer.

Tumor Immunology and Immunotherapy for Head and Neck Squamous Cell Carcinoma

The immune system plays an important role in the evolution of malignancy and has become an important target for novel antineoplastic agents. This review article focuses on key features of tumor immunology, including the role of immunotherapy in general and as it pertains to head and neck squamous cell carcinoma. Side effects, resistance mechanisms, and therapeutic monitoring strategies pertaining to immunotherapy are discussed.

Immune Evasion in Pancreatic Cancer: From Mechanisms to Therapy

Pancreatic ductal adenocarcinoma (PDA), the most frequent type of pancreatic cancer, remains one of the most challenging problems for the biomedical and clinical fields, with abysmal survival rates and poor therapy efficiency. Desmoplasia, which is abundant in PDA, can be blamed for much of the mechanisms behind poor drug performance, as it is the main source of the cytokines and chemokines that orchestrate rapid and silent tumor progression to allow tumor cells to be isolated into an extensive fibrotic reaction, which results in inefficient drug delivery. However, since immunotherapy was proclaimed as the breakthrough of the year in 2013, the focus on the stroma of pancreatic cancer has interestingly moved from activated fibroblasts to the immune compartment, trying to understand the immunosuppressive factors that play a part in the strong immune evasion that characterizes PDA. The PDA microenvironment is highly immunosuppressive and is basically composed of T regulatory cells (Tregs), tumor-associated macrophages (TAMs), and myeloid-derived suppressive cells (MDSCs), which block CD8⁺ T-cell duties in tumor recognition and clearance. Interestingly, preclinical data have highlighted the importance of this immune evasion as the source of resistance to single checkpoint immunotherapies and cancer vaccines and point at pathways that inhibit the immune attack as a key to solve the therapy puzzle. Here, we will discuss the molecular mechanisms involved in PDA immune escape as well as the state of the art of the PDA immunotherapy.

Synthetic immune niches for cancer immunotherapy

Cancer immunotherapy can successfully promote long-term anticancer immune responses, although there is still only a limited number of patients who benefit from such treatment, and it can sometimes have severe treatment-associated adverse events. Compared with systemic immunomodulation, local immunomodulation may enable more effective treatment at lower doses and, at the same time, prevent systemic toxicity. Local delivery of engineered three-dimensional scaffolds may fulfil this role by acting as synthetic immune niches that boost anticancer immunity. In this Opinion article, we highlight the potential of scaffold-based adoptive cell transfer and scaffold-based cancer vaccines that, although applied locally, can promote systemic antitumour immunity. Furthermore, we discuss how scaffold-based cancer immunotherapy may contribute to the development of the next generation of cancer treatments.

Tumor-Localized Secretion of Soluble PD1 Enhances Oncolytic Virotherapy

Oncolytic virotherapy represents an attractive option for the treatment of a variety of aggressive or refractory tumors. While this therapy is effective at rapidly debulking directly injected tumor masses, achieving complete eradication of established disease has proven difficult. One method to overcome this challenge is to use oncolytic viruses to induce secondary antitumor immune responses. Unfortunately, while the initial induction of these immune responses is typically robust, their subsequent efficacy is often inhibited through a variety of immunoregulatory mechanisms, including the PD1/PDL1 T-cell checkpoint pathway. To overcome this inhibition, we generated a novel recombinant myxoma virus (vPD1), which inhibits the PD1/PDL1 pathway specifically within the tumor microenvironment by secreting a soluble form of PD1 from infected cells. This virus both induced and maintained antitumor CD8+ T-cell responses within directly treated tumors and proved safer and more effective than combination therapy using unmodified myxoma and systemic αPD1 antibodies. Localized vPD1 treatment combined with systemic elimination of regulatory T cells had potent synergistic effects against metastatic disease that was already established in secondary solid organs. These results demonstrate that tumor-localized inhibition of the PD1/PDL1 pathway can significantly improve outcomes during oncolytic virotherapy. Furthermore, they establish a feasible path to translate these findings against clinically relevant disease. Cancer Res; 77(11); 2952-63. ©2017 AACR.

Progress and opportunities for enhancing the delivery and efficacy of checkpoint inhibitors for cancer immunotherapy

Despite the advent of immune checkpoint blockade for effective treatment of advanced malignancies, only a minority of patients responds to therapy and significant immune-related adverse events remain to be minimized. Innovations in engineered drug delivery systems and controlled release strategies can improve drug accumulation at and retention within target cells and tissues in order to enhance therapeutic efficacy while simultaneously reducing drug exposure in off target tissues to minimize the potential for treatment-associated toxicities. This review will outline basic principles of the immune physiology of checkpoint signaling, the existing knowledge of dose-efficacy relationships in checkpoint inhibition, the influence of administration route on treatment efficacy, as well as the resulting checkpoint inhibitor antibody biodistribution profiles amongst target versus systemic tissues. It will also highlight recent successes in the application of drug delivery principles and technologies towards augmenting checkpoint blockade therapy in cancer. Delivery strategies that have been developed for other therapeutic and immunotherapy applications with as-of-yet underexplored potential in checkpoint inhibition therapy will also be discussed.

CAR T-cell therapy for pancreatic cancer

Chimeric antigen receptor (CAR) T-cell therapy utilizes genetic engineering to redirect a patient's own T cells to target cancer cells. The remarkable results in hematological malignancies prompted investigating this approach in solid tumors such as pancreatic cancer. The complex tumor microenvironment, stromal hindrance in limiting immune response, and expression of checkpoint blockade on T cells pose hurdles. Herein, we summarize the opportunities, challenges, and state of knowledge in targeting pancreatic cancer with CAR T-cell therapy.

Transformation of the tumour microenvironment by a CD40 agonist antibody correlates with improved responses to PD-L1 blockade in a mouse orthotopic pancreatic tumour model

Despite the availability of recently developed chemotherapy regimens, survival times for pancreatic cancer patients remain poor. These patients also respond poorly to immune checkpoint blockade therapies (anti-CTLA-4, anti-PD-L1, anti-PD-1), which suggests the presence of additional immunosuppressive mechanisms in the pancreatic tumour microenvironment (TME). CD40 agonist antibodies (αCD40) promote antigen presenting cell (APC) maturation and enhance macrophage tumouricidal activity, and may therefore alter the pancreatic TME to increase sensitivity to immune checkpoint blockade. Here, we test whether αCD40 transforms the TME in a mouse syngeneic orthotopic model of pancreatic cancer, to increase sensitivity to PD-L1 blockade. We found that whilst mice bearing orthotopic Pan02 tumours responded poorly to PD-L1 blockade, αCD40 improved overall survival. αCD40 transformed the TME, upregulating Th1 chemokines, increasing cytotoxic T cell infiltration and promoting formation of an immune cell-rich capsule separating the tumour from the normal pancreas. Furthermore, αCD40 drove systemic APC maturation, memory T cell expansion, and upregulated tumour and systemic PD-L1 expression. Combining αCD40 with PD-L1 blockade enhanced anti-tumour immunity and improved overall survival versus either monotherapy. These data provide further support for the potential of combining αCD40 with immune checkpoint blockade to promote anti-tumour immunity in pancreatic cancer.

The differentiation and plasticity of Tc17 cells are regulated by CTLA-4-mediated effects on STATs

As the blockade of inhibitory surface-molecules such as CTLA-4 on T cells has led to recent advances in antitumor immune therapy, there is great interest in identifying novel mechanisms of action of CD8⁺ T cells to evoke effective cytotoxic antitumor responses. Using in vitro and in vivo models, we investigated the molecular pathways underlying the CTLA-4-mediated differentiation of IL-17-producing CD8⁺ T cells (Tc17 cells) that strongly impairs cytotoxicity. Our studies demonstrate that Tc17 cells lacking CTLA-4 signaling have limited production of STAT3-target gene products such as IL-17, IL-21, IL-23R and RORγt. Upon re-stimulation with IL-12, these cells display fast downregulation of Tc17 hallmarks and acquire Tc1 characteristics such as IFNγ and TNF-α co-expression, which is known to correlate with tumor control. Indeed, upon adoptive transfer, these cells were highly efficient in the antigen-specific rejection of established OVA-expressing B16 melanoma in vivo. Mechanistically, in primary and re-stimulated Tc17 cells, STAT3 binding to the IL-17 promoter was strongly augmented by CTLA-4, associated with less binding of STAT5 and reduced relative activation of STAT1 which is known to block STAT3 activity. Inhibiting CTLA-4-induced STAT3 activity reverses enhancement of signature Tc17 gene products, rendering Tc17 cells susceptible to conversion to Tc1-like cells with enhanced cytotoxic potential. Thus, CTLA-4 critically shapes the characteristics of Tc17 cells by regulating relative STAT3 activation, which provides new perspectives to enhance cytotoxicity of antitumor responses.

Local checkpoint inhibition of CTLA-4 as a monotherapy or in combination with anti-PD1 prevents the growth of murine bladder cancer

Checkpoint blockade of CTLA-4 results in long-lasting survival benefits in metastatic cancer patients. However, patients treated with CTLA-4 blockade have suffered from immune-related adverse events, most likely due to the breadth of the induced T-cell activation. Here, we investigated the efficacy of a local low-dose anti-CTLA-4 administration for treatment of subcutaneous or orthotopic murine bladder 49 (MB49) bladder carcinoma in C57BL/6 mice. When MB49 tumors were grown s.c., peritumoral (p.t.) injection of anti-CTLA-4 treatment was equally effective as intravenous or s.c. (nontumor bearing flank) administration. Notably, p.t. injection was associated with lower circulating antibody levels and decreased IL-6 serum levels as compared to systemic treatment. Ultrasound-guided intratumoral anti-CTLA-4 antibody treatment of orthotopically growing MB49 tumors resulted in tumor regression, with more than tenfold reduction in systemic antibody levels as compared to i.v. or s.c. administration, in line with the compartmentally restrained nature of the bladder. Local anti-CTLA-4 therapy in combination with anti-PD-1 therapy resulted in complete responses, superior to each therapy alone. In addition, p.t. anti-CTLA-4 therapy was potentiated by depletion of regulatory T cells. Our results demonstrate that local anti-CTLA-4 antibody therapy is equally effective as systemic administration, but reduces systemic antibody levels and cytokine release, and enhances the response to anti-PD1 therapy.