Immune checkpoint combinations from mouse to man

Effect of lymphoid volume irradiation on radiation-induced lymphopenia in head and neck cancers

PURPOSE

Radiotherapy induces significant and prolonged lymphopenia in head and neck cancer patients with poorer outcomes and reduced survival. Irradiated volumes may be correlated with lymphopenia with a potential impact on immunotherapy efficacy. We assessed associations between volumes treated with radiotherapy and the nadir of the lymphocyte count in patients with head and neck cancer.

MATERIALS AND METHODS

We conducted a monocentric retrospective study in patients with head and neck cancer treated with radiation. Univariate analysis used regression analysis to model nadir lymphocyte count and radiotherapy volumes; multivariate analysis then modelled factors associated with nadir lymphocyte count.

RESULTS

Of the 77 included patients, 97% presented lymphopenia during radiotherapy with an average nadir of 431 cells/mm³ at a median of 40 days after the beginning of treatment. The volume of high-risk radiotherapy and gross tumour volume were correlated with nadir lymphocyte count with a Spearman coefficient of -0.267 (P=0.019) and -0.387 (P=0.001), respectively. After multivariate linear regression, high-risk radiotherapy was significantly associated with nadir lymphocyte count with a regression coefficient of -0.32 (per cubic centimetre) [95% CI=-0.60; -0.03] (P=0.028).

CONCLUSION

High-risk radiotherapy was significantly associated with nadir lymphocyte count in patients with head and neck cancer treated with radiation. Sparing lymphoid volumes from irradiation by elective nodal irradiation or proton therapy may limit lymphopenia and needs to be investigated in combination with immunotherapy.

Animal models for studies of HIV-1 brain reservoirs

The HIV-1 often evades a robust antiretroviral-mediated immune response, leading to persistent infection within anatomically privileged sites including the CNS. Continuous low-level infection occurs in the presence of effective antiretroviral therapy (ART) in CD4+ T cells and mononuclear phagocytes (MP; monocytes, macrophages, microglia, and dendritic cells). Within the CNS, productive viral infection is found exclusively in microglia and meningeal, perivascular, and choroidal macrophages. MPs serve as the principal viral CNS reservoir. Animal models have been developed to recapitulate natural human HIV-1 infection. These include nonhuman primates, humanized mice, EcoHIV, and transgenic rodent models. These models have been used to study disease pathobiology, antiretroviral and immune modulatory agents, viral reservoirs, and eradication strategies. However, each of these models are limited to specific component(s) of human disease. Indeed, HIV-1 species specificity must drive therapeutic and cure studies. These have been studied in several model systems reflective of latent infections, specifically in MP (myeloid, monocyte, macrophages, microglia, and histiocyte cell) populations. Therefore, additional small animal models that allow productive viral replication to enable viral carriage into the brain and the virus-susceptible MPs are needed. To this end, this review serves to outline animal models currently available to study myeloid brain reservoirs and highlight areas that are lacking and require future research to more effectively study disease-specific events that could be useful for viral eradication studies both in and outside the CNS.

Injectable Nanoparticle-Based Hydrogels Enable the Safe and Effective Deployment of Immunostimulatory CD40 Agonist Antibodies

When properly deployed, the immune system can eliminate deadly pathogens, eradicate metastatic cancers, and provide long-lasting protection from diverse diseases. Unfortunately, realizing these remarkable capabilities is inherently risky as disruption to immune homeostasis can elicit dangerous complications or autoimmune disorders. While current research is continuously expanding the arsenal of potent immunotherapeutics, there is a technological gap when it comes to controlling when, where, and how long these drugs act on the body. Here, this study explored the ability of a slow-releasing injectable hydrogel depot to reduce dose-limiting toxicities of immunostimulatory CD40 agonist (CD40a) while maintaining its potent anticancer efficacy. A previously described polymer-nanoparticle (PNP) hydrogel system is leveraged that exhibits shear-thinning and yield-stress properties that are hypothesized to improve locoregional delivery of CD40a immunotherapy. Using positron emission tomography, it is demonstrated that prolonged hydrogel-based delivery redistributes CD40a exposure to the tumor and the tumor draining lymph node (TdLN), thereby reducing weight loss, hepatotoxicity, and cytokine storm associated with standard treatment. Moreover, CD40a-loaded hydrogels mediate improved local cytokine induction in the TdLN and improve treatment efficacy in the B16F10 melanoma model. PNP hydrogels, therefore, represent a facile, drug-agnostic method to ameliorate immune-related adverse effects and explore locoregional delivery of immunostimulatory drugs.

The Status of Adjuvant and Neoadjuvant Melanoma Therapy, New Developments and Upcoming Challenges

The global incidence of malignant melanoma, the leading cause of skin cancer death, has steadily increased in recent years. Surgical excision is the treatment of choice for early-stage melanoma. However, 40-60% of patients with high-risk melanoma or with nodal involvement eventually experience loco-regional relapse or tumor progression. Adjuvant therapy aims to reduce the rate of recurrence in radically operated high-risk patients with melanoma and thus improves survival. Interferon-α has long been the only approved drug for adjuvant melanoma therapy, despite an unclear survival benefit. The landmark success of immune-checkpoint inhibitors and BRAF/MEK-directed targeted therapies in the treatment of patients with stage IV melanoma led to the initiation of clinical trials in the adjuvant setting. These trials demonstrated the efficacy of immune-checkpoint inhibitors and targeted therapies for the adjuvant treatment of high-risk patients with melanoma, as shown both by an increase in recurrence-free survival and the emergence of long-term survivors, finally resulting in the approval of the cytotoxic T-lymphocyte antigen 4 inhibitor ipilimumab, PD1 inhibitors (nivolumab, pembrolizumab), and BRAF/MEK inhibitors for adjuvant melanoma therapy. This review aims to delineate the advances in adjuvant melanoma therapy, issuing particularly recent results from clinical trials. Moreover, we also discuss pending issues and future challenges, which comprise the adequate selection of adjuvant regimens for patient subgroups and the identification of markers likely to predict the individual response to adjuvant treatments. Last, we outline the role of emerging neoadjuvant approaches, which may complement adjuvant strategies and are currently investigated in clinical trials.

mRNA-Based Cancer Vaccines: A Therapeutic Strategy for the Treatment of Melanoma Patients

Malignant melanoma is one of the most aggressive forms of cancer and the leading cause of death from skin tumors. Given the increased incidence of melanoma diagnoses in recent years, it is essential to develop effective treatments to control this disease. In this regard, the use of cancer vaccines to enhance cell-mediated immunity is considered to be one of the most modern immunotherapy options for cancer treatment. The most recent cancer vaccine options are mRNA vaccines, with a focus on their usage as modern treatments. Advantages of mRNA cancer vaccines include their rapid production and low manufacturing costs. mRNA-based vaccines are also able to induce both humoral and cellular immune responses. In addition to the many advantages of mRNA vaccines for the treatment of cancer, their use is associated with a number of challenges. For this reason, before mRNA vaccines can be used for the treatment of cancer, comprehensive information about them is required and a large number of trials need to be conducted. Here, we reviewed the general features of mRNA vaccines, including their basis, stabilization, and delivery methods. We also covered clinical trials involving the use of mRNA vaccines in melanoma cancer and the challenges involved with this type of treatment. This review also emphasized the combination of treatment with mRNA vaccines with the use of immune-checkpoint blockers to enhance cell-mediated immunity.

Combinatorial therapy in tumor microenvironment: Where do we stand?

The tumor microenvironment plays a pivotal role in tumor initiation and progression by creating a dynamic interaction with cancer cells. The tumor microenvironment consists of various cellular components, including endothelial cells, fibroblasts, pericytes, adipocytes, immune cells, cancer stem cells and vasculature, which provide a sustained environment for cancer cell proliferation. Currently, targeting tumor microenvironment is increasingly being explored as a novel approach to improve cancer therapeutics, as it influences the growth and expansion of malignant cells in various ways. Despite continuous advancements in targeted therapies for cancer treatment, drug resistance, toxicity and immune escape mechanisms are the basis of treatment failure and cancer escape. Targeting tumor microenvironment efficiently with approved drugs and combination therapy is the solution to this enduring challenge that involves combining more than one treatment modality such as chemotherapy, surgery, radiotherapy, immunotherapy and nanotherapy that can effectively and synergistically target the critical pathways associated with disease pathogenesis. This review shed light on the composition of the tumor microenvironment, interaction of different components within tumor microenvironment with tumor cells and associated hallmarks, the current status of combinatorial therapies being developed, and various growing advancements. Furthermore, computational tools can also be used to monitor the significance and outcome of therapies being developed. We addressed the perceived barriers and regulatory hurdles in developing a combinatorial regimen and evaluated the present status of these therapies in the clinic. The accumulating depth of knowledge about the tumor microenvironment in cancer may facilitate further development of effective treatment modalities. This review presents the tumor microenvironment as a sweeping landscape for developing novel cancer therapies.

Humanized Mice for Infectious and Neurodegenerative disorders

Humanized mice model human disease and as such are used commonly for research studies of infectious, degenerative and cancer disorders. Recent models also reflect hematopoiesis, natural immunity, neurobiology, and molecular pathways that influence disease pathobiology. A spectrum of immunodeficient mouse strains permit long-lived human progenitor cell engraftments. The presence of both innate and adaptive immunity enables high levels of human hematolymphoid reconstitution with cell susceptibility to a broad range of microbial infections. These mice also facilitate investigations of human pathobiology, natural disease processes and therapeutic efficacy in a broad spectrum of human disorders. However, a bridge between humans and mice requires a complete understanding of pathogen dose, co-morbidities, disease progression, environment, and genetics which can be mirrored in these mice. These must be considered for understanding of microbial susceptibility, prevention, and disease progression. With known common limitations for access to human tissues, evaluation of metabolic and physiological changes and limitations in large animal numbers, studies in mice prove important in planning human clinical trials. To these ends, this review serves to outline how humanized mice can be used in viral and pharmacologic research emphasizing both current and future studies of viral and neurodegenerative diseases. In all, humanized mouse provides cost-effective, high throughput studies of infection or degeneration in natural pathogen host cells, and the ability to test transmission and eradication of disease.

geneshot: gene-level metagenomics identifies genome islands associated with immunotherapy response

Researchers must be able to generate experimentally testable hypotheses from sequencing-based observational microbiome experiments to discover the mechanisms underlying the influence of gut microbes on human health. We describe geneshot, a novel bioinformatics tool for identifying testable hypotheses based on gene-level metagenomic analysis of WGS microbiome data. By applying geneshot to two independent previously published cohorts, we identify microbial genomic islands consistently associated with response to immune checkpoint inhibitor (ICI)-based cancer treatment in culturable type strains. The identified genomic islands are within operons involved in type II secretion, TonB-dependent transport, and bacteriophage growth.

How Computational Chemistry and Drug Delivery Techniques Can Support the Development of New Anticancer Drugs

The early and late development of new anticancer drugs, small molecules or peptides can be slowed down by some issues such as poor selectivity for the target or poor ADME properties. Computer-aided drug design (CADD) and target drug delivery (TDD) techniques, although apparently far from each other, are two research fields that can give a significant contribution to overcome these problems. Their combination may provide mechanistic understanding resulting in a synergy that makes possible the rational design of novel anticancer based therapies. Herein, we aim to discuss selected applications, some also from our research experience, in the fields of anticancer small organic drugs and peptides.

Cancer Vaccines and Oncolytic Viruses Exert Profoundly Lower Side Effects in Cancer Patients than Other Systemic Therapies: A Comparative Analysis

This review compares cytotoxic drugs, targeted therapies, and immunotherapies with regard to mechanisms and side effects. Targeted therapies relate to small molecule inhibitors. Immunotherapies include checkpoint inhibitory antibodies, chimeric antigen receptor (CAR) T-cells, cancer vaccines, and oncolytic viruses. All these therapeutic approaches fight systemic disease, be it micro-metastatic or metastatic. The analysis includes only studies with a proven therapeutic effect. A clear-cut difference is observed with regard to major adverse events (WHO grades 3-4). Such severe side effects are not observed with cancer vaccines/oncolytic viruses while they are seen with all the other systemic therapies. Reasons for this difference are discussed.

B7-H7 (HHLA2) inhibits T-cell activation and proliferation in the presence of TCR and CD28 signaling

Modulation of T-cell responses has played a key role in treating cancers and autoimmune diseases. Therefore, understanding how different receptors on T cells impact functional outcomes is crucial. The influence of B7-H7 (HHLA2) and CD28H (TMIGD2) on T-cell activation remains controversial. Here we examined global transcriptomic changes in human T cells induced by B7-H7. Stimulation through TCR with OKT3 and B7-H7 resulted in modest fold changes in the expression of select genes; however, these fold changes were significantly lower than those induced by OKT3 and B7-1 stimulation. The transcriptional changes induced by OKT3 and B7-H7 were insufficient to provide functional stimulation as measured by evaluating T-cell proliferation and cytokine production. Interestingly, B7-H7 was coinhibitory when simultaneously combined with TCR and CD28 stimulation. This inhibitory activity was comparable to that observed with PD-L1. Finally, in physiological assays using T cells and APCs, blockade of B7-H7 enhanced T-cell activation and proliferation, demonstrating that this ligand acts as a break signal. Our work defines that the transcriptomic changes induced by B7-H7 are insufficient to support full costimulation with TCR signaling and, instead, B7-H7 inhibits T-cell activation and proliferation in the presence of TCR and CD28 signaling.

Differential Modulation of Human Innate Lymphoid Cell (ILC) Subsets by IL-10 and TGF-β

Using multiparameter flow cytometry human innate lymphoid cell (ILC) subsets can be detected in the circulation, in relatively low frequencies. Despite the low frequency of ILCs in circulation, ex vivo experiments have demonstrated that these ILCs release extremely large per cell quantities of signature ILC cytokines following activation. To determine how activated ILC cytokine production is regulated, ILC subsets were activated in the presence or absence of the immunoregulatory cytokines IL-10 and TGF-β. An examination of circulating ILC subsets revealed surface expression of IL-10Rα and mRNA expression of both IL-10Rα and TGF-βR1 for all ILC subsets. Stimulated ILC1 production of IFN-γ was decreased by TGF-β and not IL-10. Interestingly, ILC2s stimulated in the presence of IL-10 had a marked reduction in cytokine production of IL-5 and IL-13 while TGF-β had no effect on ILC2 cytokine production. Ex vivo activated ILC1 and ILC2 subsets were also found to be a source of the immunoregulatory cytokine IL-10, raising the potential for ILC-mediated regulation of immune cells. These findings demonstrate the differential effects of immunoregulatory cytokines IL-10 and TGF-β on activated ILC1 and ILC2 populations ex vivo.

Immunity, Hypoxia, and Metabolism-the Ménage à Trois of Cancer: Implications for Immunotherapy

It is generally accepted that metabolism is able to shape the immune response. Only recently we are gaining awareness that the metabolic crosstalk between different tumor compartments strongly contributes to the harsh tumor microenvironment (TME) and ultimately impairs immune cell fitness and effector functions. The major aims of this review are to provide an overview on the immune system in cancer; to position oxygen shortage and metabolic competition as the ground of a restrictive TME and as important players in the anti-tumor immune response; to define how immunotherapies affect hypoxia/oxygen delivery and the metabolic landscape of the tumor; and vice versa, how oxygen and metabolites within the TME impinge on the success of immunotherapies. By analyzing preclinical and clinical endeavors, we will discuss how a metabolic characterization of the TME can identify novel targets and signatures that could be exploited in combination with standard immunotherapies and can help to predict the benefit of new and traditional immunotherapeutic drugs.

Adverse Effects of Immune Checkpoint Inhibitors (Programmed Death-1 Inhibitors and Cytotoxic T-Lymphocyte-Associated Protein-4 Inhibitors): Results of a Retrospective Study

In recent years the use of immunomodulating therapy to treat various cancers has been on the rise. Three checkpoint inhibitors have been approved by the Food and Drug Administration (ipilimumab, pembrolizumab and nivolumab). The use of these drugs comes with serious adverse events related to excessive immune activation, collectively known as immune-related adverse events (irAEs). We conducted a system-based review of 139 case reports/case series that have described these adverse events between January 2016 and April 2018, found in the PubMed database. There was a broad spectrum of presentations, doses and checkpoint inhibitors used. The most common check point inhibitor observed in our literature review was nivolumab. The most common adverse effects encountered were colitis (14/139), hepatitis (11/139), adrenocorticotropic hormone insufficiency (12/139), hypothyroidism (7/139), type 1 diabetes (22/139), acute kidney injury (16/139) and myocarditis (10/139). The treatment most commonly consisted of cessation of the immune checkpoint inhibitor, initiation of steroids and supportive therapy. This approach provided a complete resolution in a majority of cases; however, there were many that developed long-term adverse events with deaths reported in a few cases. The endocrine system was the mostly commonly affected with the development of type 1 diabetes mellitus or diabetic ketoacidosis being the most frequently reported adverse events. While immunomodulating therapy is a significant advance in the management of various malignancies, it is capable of serious adverse effects. Because the majority of the cases developed pancreatic dysfunction within five cycles of therapy, in addition to the evaluation of other systems, pancreatic function should be closely monitored to minimize adverse impact on patients.

New Hope for Therapeutic Cancer Vaccines in the Era of Immune Checkpoint Modulation

The driver and passenger mutations accumulated in the process of malignant transformation offer an adequate spectrum of immune visible alterations to the cellular proteome and resulting peptidome to render these cancers targetable-and, in theory, rejectable-by the host T cell immune response. In addition, cancers often overexpress tissue-specific and developmental antigens to which immune tolerance is incomplete. Sometimes, virally transferred oncogenes drive malignant transformation and remain expressed throughout the cancer. Despite this state of antigenic sufficiency, cancer grows progressively and overcomes all efforts of the host immune system to contain it. While therapeutic cancer vaccination can mobilize high frequencies of tumor-specific T cells, these responses remain subject to intratumoral attenuation. Antibody modulation of T cell function through checkpoint blockade or costimulatory activation can restore survival, proliferation, and effector function to these tumor-infiltrating T cells and convert otherwise subtherapeutic vaccines into potentially curative cancer immunotherapeutics.

Mucosal HPV E6/E7 Peptide Vaccination in Combination with Immune Checkpoint Modulation Induces Regression of HPV+ Oral Cancers

High-risk human papillomavirus (HPV)-associated squamous cell carcinomas of the oropharynx (SCCOP) are among the fastest growing cancers. After standard-of-care treatment, however, patients with HPV⁺ SCCOP have better overall and disease-specific survival than patients with HPV^- SCCOP, suggesting the importance of HPV-specific immunity. We reasoned that therapeutic vaccination targeting the HPV-16 E6 and E7 oncogenes could elicit high-affinity, high-frequency tumor antigen-specific T-cell responses, which could then be augmented and shielded from suppression in the tumor microenvironment by immune checkpoint modulation. In this study, we used a preclinical syngeneic mouse model of oral cancer comprised of mouse tonsil-derived epithelial cells stably expressing HPV-16 E6 and E7 genes along with H-ras oncogene (mEER) to identify combinations of vaccination and checkpoint antibodies capable of promoting tumor regression. Intranasal HPV E6/E7 peptide vaccination and single checkpoint antibodies failed to elicit responses in more than half of animals; however, 4-1BB agonist antibody along with either CD40 agonist antibody or CTLA-4 blockade eliminated the majority of established mEER tumors. The combination of intranasal HPV peptide vaccine and α4-1BB and αCTLA-4 antibodies produced curative efficacy and a better safety profile against orally implanted mEER tumors. Correlates of protective immunity included enhanced intratumoral levels of CD8 T cells relative to immunosuppressive regulatory T cells and myeloid-derived suppressor cells. Overall, our results demonstrate combination vaccine-immunotherapy modalities as novel treatment options for HPV⁺ SCCOP.Significance: Combinations of vaccine and checkpoint modulation are effective and safe treatment options for HPV⁺ oral cancers. Cancer Res; 78(18); 5327-39. ©2018 AACR.

Activation of 4-1BB on Liver Myeloid Cells Triggers Hepatitis via an Interleukin-27-Dependent Pathway

Purpose: Agonist antibodies targeting the T-cell costimulatory receptor 4-1BB (CD137) are among the most effective immunotherapeutic agents across preclinical cancer models. In the clinic, however, development of these agents has been hampered by dose-limiting liver toxicity. Lack of knowledge of the mechanisms underlying this toxicity has limited the potential to separate 4-1BB agonist-driven tumor immunity from hepatotoxicity.Experimental Design: The capacity of 4-1BB agonist antibodies to induce liver toxicity was investigated in immunocompetent mice, with or without coadministration of checkpoint blockade, via (i) measurement of serum transaminase levels, (ii) imaging of liver immune infiltrates, and (iii) qualitative and quantitative assessment of liver myeloid and T cells via flow cytometry. Knockout mice were used to clarify the contribution of specific cell subsets, cytokines, and chemokines.Results: We find that activation of 4-1BB on liver myeloid cells is essential to initiate hepatitis. Once activated, these cells produce interleukin-27 that is required for liver toxicity. CD8 T cells infiltrate the liver in response to this myeloid activation and mediate tissue damage, triggering transaminase elevation. FoxP3⁺ regulatory T cells limit liver damage, and their removal dramatically exacerbates 4-1BB agonist-induced hepatitis. Coadministration of CTLA-4 blockade ameliorates transaminase elevation, whereas PD-1 blockade exacerbates it. Loss of the chemokine receptor CCR2 blocks 4-1BB agonist hepatitis without diminishing tumor-specific immunity against B16 melanoma.Conclusions: 4-1BB agonist antibodies trigger hepatitis via activation and expansion of interleukin-27-producing liver Kupffer cells and monocytes. Coadministration of CTLA-4 and/or CCR2 blockade may minimize hepatitis, but yield equal or greater antitumor immunity. Clin Cancer Res; 24(5); 1138-51. ©2018 AACR.

A cellular platform for the evaluation of immune checkpoint molecules

Blockade of the T cell coinhibitory molecules CTLA-4 and PD-1 has clinical utility to strengthen T cell responses. In addition to these immune checkpoints an ever-growing number of molecules has been implicated in generating coinhibitory signals in T cells. However, investigating coinhibitory molecules in primary human cells is complicated by the restricted expression and promiscuity of both coinhibitory receptors and their ligands. Here we have evaluated the potential of fluorescence-based transcriptional reporters based on the human Jurkat T cell line in conjunction with engineered T cell stimulator cell lines for investigating coinhibitory pathways. CTLA-4, PD-1, TIGIT, BTLA and 2B4 expressing reporter cells were generated and activated with T cell stimulator cells expressing cognate ligands of these molecules.

All accessory molecules tested were functional in our reporter system. Engagement of CTLA-4, PD-1, BTLA and TIGIT by their ligands significantly inhibited T cell activation, whereas binding of 2B4 by CD48 resulted in enhanced responses. Mutational analysis revealed intracellular motifs that are responsible for BTLA mediated T cell inhibition and demonstrates potent reporter inhibition by CTLA-4 independent of cytoplasmic signaling motifs. Moreover, considerably higher IC50 values were measured for the CTLA-4 blocker Ipilimumab compared to the PD-1 antibody Nivolumab.

Our findings show that coinhibitory pathways can be evaluated in Jurkat-based transcriptional reporters and yield novel insights on their function. Results obtained from this robust reductionist system can complement more time consuming and complex studies of such pathways in primary T cells.

Immune checkpoints and their inhibition in cancer and infectious diseases

The development of chronic infections and cancer is facilitated by a variety of immune subversion mechanisms, such as the production of anti-inflammatory cytokines, induction of regulatory T (Treg) cells, and expression of immune checkpoint molecules, including CTLA-4 and PD-1. CTLA-4, expressed on T cells, interacts with CD80/CD86, thereby limiting T-cell activation and leading to anergy. PD-1 is predominantly expressed on T cells and its interaction with PD-L1 and PD-L2 expressed on antigen-presenting cells (APCs) and tumors sends a negative signal to T cells, which can lead to T-cell exhaustion. Given their role in suppressing effector T-cell responses, immune checkpoints are being targeted for the treatment of cancer. Indeed, antibodies binding to CTLA-4, PD-1, or PD-L1 have shown remarkable efficacy, especially in combination therapies, for a number of cancers and have been licensed for the treatment of melanoma, nonsmall cell lung cancer, and renal and bladder cancers. Moreover, immune checkpoint inhibitors have been shown to enhance ex vivo effector T-cell responses from patients with chronic viral, bacterial, or parasitic infection, including HIV, tuberculosis, and malaria. Although the data from clinical trials in infectious diseases are still sparse, these inhibitors have great potential for treating chronic infections, especially when combined with therapeutic vaccines.

Identifying and Creating the Next Generation of Community-Based Cancer Prevention Studies: Summary of a National Cancer Institute Think Tank

In late 2015, the NCI Division of Cancer Prevention convened cancer prevention research experts and stakeholders to discuss the current state of cancer prevention research, identify key prevention research priorities for the NCI, and identify studies that could be conducted within the NCI Community Oncology Research Program. Goals included identifying cancer prevention research opportunities offering the highest return on investment, exploring the concept of precision prevention and what is needed to advance this area of research, and identifying possible targets for prevention. Four study populations were considered for cancer prevention research: healthy people, those at increased risk for a specific cancer, people with preneoplastic lesions, and children, adolescents, and young adults. Priorities that emerged include screening (e.g., surveillance intervals, tomosynthesis vs. digital mammography), a pre-cancer genome atlas (PreTCGA), HPV vaccines, immunoprevention of noninfectious origins, and overdiagnosis. Challenges exist, as the priority list is ambitious and potentially expensive. Clinical trials need to be carefully designed to include and maximize prospective tissue collection. Exploring existing cofunding mechanisms will likely be necessary. Finally, relationships with a new generation of physician specialists will need to be cultivated to reach the target populations. Cancer Prev Res; 10(2); 99-107. ©2016 AACR.

Metabolic consequences of inflammatory disruption of the blood-brain barrier in an organ-on-chip model of the human neurovascular unit

Background

Understanding blood-brain barrier responses to inflammatory stimulation (such as lipopolysaccharide mimicking a systemic infection or a cytokine cocktail that could be the result of local or systemic inflammation) is essential to understanding the effect of inflammatory stimulation on the brain. It is through the filter of the blood-brain barrier that the brain responds to outside influences, and the blood-brain barrier is a critical point of failure in neuroinflammation. It is important to note that this interaction is not a static response, but one that evolves over time. While current models have provided invaluable information regarding the interaction between cytokine stimulation, the blood-brain barrier, and the brain, these approaches—whether in vivo or in vitro—have often been only snapshots of this complex web of interactions.

Methods

We utilize new advances in microfluidics, organs-on-chips, and metabolomics to examine the complex relationship of inflammation and its effects on blood-brain barrier function ex vivo and the metabolic consequences of these responses and repair mechanisms. In this study, we pair a novel dual-chamber, organ-on-chip microfluidic device, the NeuroVascular Unit, with small-volume cytokine detection and mass spectrometry analysis to investigate how the blood-brain barrier responds to two different but overlapping drivers of neuroinflammation, lipopolysaccharide and a cytokine cocktail of IL-1β, TNF-α, and MCP1,2.

Results

In this study, we show that (1) during initial exposure to lipopolysaccharide, the blood-brain barrier is compromised as expected, with increased diffusion and reduced presence of tight junctions, but that over time, the barrier is capable of at least partial recovery; (2) a cytokine cocktail also contributes to a loss of barrier function; (3) from this time-dependent cytokine activation, metabolic signature profiles can be obtained for both the brain and vascular sides of the blood-brain barrier model; and (4) collectively, we can use metabolite analysis to identify critical pathways in inflammatory response.

Conclusions

Taken together, these findings present new data that allow us to study the initial effects of inflammatory stimulation on blood-brain barrier disruption, cytokine activation, and metabolic pathway changes that drive the response and recovery of the barrier during continued inflammatory exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0760-y) contains supplementary material, which is available to authorized users.

Humanized Mouse Models of Clinical Disease

Immunodeficient mice engrafted with functional human cells and tissues, that is, humanized mice, have become increasingly important as small, preclinical animal models for the study of human diseases. Since the description of immunodeficient mice bearing mutations in the IL2 receptor common gamma chain (IL2rg^null) in the early 2000s, investigators have been able to engraft murine recipients with human hematopoietic stem cells that develop into functional human immune systems. These mice can also be engrafted with human tissues such as islets, liver, skin, and most solid and hematologic cancers. Humanized mice are permitting significant progress in studies of human infectious disease, cancer, regenerative medicine, graft-versus-host disease, allergies, and immunity. Ultimately, use of humanized mice may lead to the implementation of truly personalized medicine in the clinic. This review discusses recent progress in the development and use of humanized mice and highlights their utility for the study of human diseases.

Adverse Events Associated with Immune Checkpoint Blockade in Patients with Cancer: A Systematic Review of Case Reports

Background

Three checkpoint inhibitor drugs have been approved by the US Food and Drug Administration for use in specific types of cancers. While the results are promising, severe immunotherapy-related adverse events (irAEs) have been reported.

Objectives

To conduct a systematic review of case reports describing the occurrence of irAEs in patients with cancer following checkpoint blockade therapy, primarily to identify potentially unrecognized or unusual clinical findings and toxicity.

Data Sources

We searched Medline, EMBASE, Web of Science, PubMed ePubs, and Cochrane CENTRAL with no restriction through August 2015.

Study Selection

Studies reporting cases of cancer develop irAEs following treatment with anti CTLA-4 (ipilimumab) or anti PD-1 (nivolumab or pembrolizumab) antibodies were included.

Data Extraction

We extracted data on patient characteristics, irAEs characteristics, how irAEs were managed, and their outcomes.

Data Synthesis

191 publications met inclusion criteria, reporting on 251 cases. Most patients had metastatic melanoma (95.6%), and the majority were treated with ipilimumab (93.2%). Autoimmune colitis, hepatitis, endocrinopathies, and cutaneous irAEs were the most frequently reported irAEs in ipilimumab treated patients. A broad spectrum of toxicities were reported for almost every body system. Moreover, well-defined diseases such as sarcoidosis, polyarthritis, polymyalgia rheumatica/arteritis, lupus, celiac disease, dermatomyositis, and Vogt-Koyanagi-like syndrome were reported. The most frequent irAEs reported with anti-PD1 agents were dermatitis for pembrolizumab, and thyroid disease and pneumonitis for nivolumab. Complete resolution of adverse events occurred in most cases. However, persistent irAEs and death were reported, mainly in patients treated with ipilimumab.

Limitations

Our study is limited by information available in the original reports.

Conclusions

Evidence from case reports shows that cancer patients develop irAEs following checkpoint blockade therapy, and can occasionally develop clearly defined autoimmune systemic diseases. While discontinuation of therapy and/or treatment can result in resolution of irAEs, long-term sequelae and death have been reported.

The human antibody fragment DIATHIS1 specific for CEACAM1 enhances natural killer cell cytotoxicity against melanoma cell lines in vitro

Supplemental Digital Content is available in the text.

Several lines of evidence show that de novo expression of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) is strongly associated with reduced disease-free survival of patients affected by metastatic melanoma. Previously published investigations report that homophilic interactions between CEACAM1 expressed on natural killer (NK) cells and tumors inhibit the NK cell-mediated killing independently of major histocompatibility complex class I recognition. This biological property can be physiologically relevant in metastatic melanoma because of the increased CEACAM1 expression observed on NK cells from some patients. Moreover, this inhibitory mechanism in many cases might hinder the efficacy of immunotherapeutic treatments of CEACAM1⁺ malignancies because of tumor evasion by activated effector cells. In the present study, we designed an in vitro experimental model showing that the human single-chain variable fragment (scFv) DIATHIS1 specific for CEACAM1 is able to enhance the lytic machinery of NK cells against CEACAM1⁺ melanoma cells. The coincubation of the scFv DIATHIS1 with CEACAM1⁺ melanoma cells and NK-92 cell line significantly increases the cell-mediated cytotoxicity. Moreover, pretreatment of melanoma cells with scFv DIATHIS1 promotes the activation and the degranulation capacity of in vitro–expanded NK cells from healthy donors. It is interesting to note that the melanoma cell line MelC and the primary melanoma cells STA that respond better to DIATHIS1 treatment, express higher relative levels of CEACAM1-3L and CEACAM1-3S splice variants isoforms compared with Mel501 cells that are less responsive to DIATHIS1-induced NK cell–mediated cytotoxicity. Taken together, our results suggest that the fully human antibody fragment DIATHIS1 originated by biopanning approach from a phage antibody library may represent a relevant biotechnological platform to design and develop completely human antimelanoma therapeutics of biological origin.

Facilitating T Cell Infiltration in Tumor Microenvironment Overcomes Resistance to PD-L1 Blockade

Immune checkpoint blockade therapies fail to induce responses in the majority of cancer patients, so how to increase the objective response rate becomes an urgent challenge. Here, we demonstrate that sufficient T cell infiltration in tumor tissues is a prerequisite for response to PD-L1 blockade. Targeting tumors with tumor necrosis factor superfamily member LIGHT activates lymphotoxin β-receptor signaling, leading to the production of chemokines that recruit massive numbers of T cells. Furthermore, targeting non-T cell-inflamed tumor tissues by antibody-guided LIGHT creates a T cell-inflamed microenvironment and overcomes tumor resistance to checkpoint blockade. Our data indicate that targeting LIGHT might be a potent strategy to increase the responses to checkpoint blockades and other immunotherapies in non-T cell-inflamed tumors.

Immunotherapy and tumor microenvironment

Recent exciting progress in cancer immunotherapy has ushered in a new era of cancer treatment. Immunotherapy can elicit unprecedented durable responses in advanced cancer patients that are much greater than conventional chemotherapy. However, such responses only occur in a relatively small fraction of patients. A positive response to immunotherapy usually relies on dynamic interactions between tumor cells and immunomodulators inside the tumor microenvironment (TME). Depending on the context of these interactions, the TME may play important roles to either dampen or enhance immune responses. Understanding the interactions between immunotherapy and the TME is not only critical to dissect the mechanisms of action but also important to provide new approaches in improving the efficiency of current immunotherapies. In this review, we will highlight recent work on how the TME can influence the efficacy of immunotherapy as well as how manipulating the TME can improve current immunotherapy regimens in some cases.

Immunotherapy Combinations With Checkpoint Inhibitors in Metastatic Melanoma: Current Approaches and Future Directions

Based on the complexity of the immune response to cancer and the mechanisms of tumor evasion, it is likely that therapeutic modulation of multiple immune-mediated pathways will be needed to maximally induce tumor regression in patients with advanced melanoma. The rationale of using combination checkpoint inhibitor-based regimens may include the concomitant effects on re-activation of T cells, increased trafficking of tumor reactive lymphocytes into the tumor tissue, and enhanced killing of cancer cells. The administration of nivolumab in combination with ipilimumab demonstrated increased response rates, tumor shrinkage, and median progression-free survival using combined therapy compared with either treatment alone. Although toxicity was also increased, this trial established proof of principle that combination immunotherapy could enhance the efficacy seen with single-agent programmed cell death protein-1 (PD-1) pathway blockade for the unselected patient. Current and future trials are evaluating alternative schedules and other combinations of immunotherapies to determine if they could provide similar efficacy with less toxicity. In addition, efforts are underway to determine how best to integrate combination immunotherapy with other treatment approaches for patients with advanced melanoma.

Immune checkpoint targeting as anti-cancer immunotherapy: promises, questions, challenges and the need for predictive biomarkers at ASCO 2015

Immunotherapy targeting "immune checkpoints" first made the headlines at the ASCO (American Society of Clinical Oncology) Annual Meeting in 2013, took centre stage at 2014 and consolidated its position as a potentially curative first-line therapy as reflected by the presentations at ASCO 2015. For the first time, previously refractory cancers are proving amenable to treatment, but still only a fraction, usually a minority, of patients respond. The hunt for factors predicting responses and for biomarkers to monitor treatment was a major theme of this year's meeting, as briefly discussed in this Editorial.

CTLA-4 Blockade Synergizes Therapeutically with PARP Inhibition in BRCA1-Deficient Ovarian Cancer

Immune checkpoint blockade has shown significant therapeutic efficacy in melanoma and other solid tumors, but results in ovarian cancer have been limited. With evidence that tumor immunogenicity modulates the response to checkpoint blockade, and data indicating that BRCA-deficient ovarian cancers express higher levels of immune response genes, we hypothesized that BRCA(-) ovarian tumors would be vulnerable to checkpoint blockade. To test this hypothesis, we used an immunocompetent BRCA1-deficient murine ovarian cancer model to compare treatment with CTLA-4 or PD-1/PD-L1 antibodies alone or combined with targeted cytotoxic therapy using a PARP inhibitor. Correlative studies were performed in vitro using human BRCA1(-) cells. We found that CTLA-4 antibody, but not PD-1/PD-L1 blockade, synergized therapeutically with the PARP inhibitor, resulting in immune-mediated tumor clearance and long-term survival in a majority of animals (P < 0.0001). The survival benefit of this combination was T-cell mediated and dependent on increases in local IFNγ production in the peritoneal tumor environment. Evidence of protective immune memory was observed more than 60 days after completion of therapy. Similar increases in the cytotoxic effect of PARP inhibition in the presence of elevated levels of IFNγ in human BRCA1(-) cancer cells support the translational potential of this treatment protocol. These results demonstrate that CTLA-4 blockade combined with PARP inhibition induces protective antitumor immunity and significant survival benefit in the BRCA1(-) tumor model, and support clinical testing of this regimen to improve outcomes for women with hereditary ovarian cancer.

4-1BB Agonists: Multi-Potent Potentiators of Tumor Immunity

Immunotherapy is a rapidly expanding field of oncology aimed at targeting, not the tumor itself, but the immune system combating the cancerous lesion. Of the many approaches currently under study to boost anti-tumor immune responses; modulation of immune co-receptors on lymphocytes in the tumor microenvironment has thus far proven to be the most effective. Antibody blockade of the T cell co-inhibitory receptor cytotoxic T lymphocyte antigen-4 (CTLA-4) has become the first FDA approved immune checkpoint blockade; however, tumor infiltrating lymphocytes express a diverse array of additional stimulatory and inhibitory co-receptors, which can be targeted to boost tumor immunity. Among these, the co-stimulatory receptor 4-1BB (CD137/TNFSF9) possesses an unequaled capacity for both activation and pro-inflammatory polarization of anti-tumor lymphocytes. While functional studies of 4-1BB have focused on its prominent role in augmenting cytotoxic CD8 T cells, 4-1BB can also modulate the activity of CD4 T cells, B cells, natural killer cells, monocytes, macrophages, and dendritic cells. 4-1BB’s expression on both T cells and antigen presenting cells, coupled with its capacity to promote survival, expansion, and enhanced effector function of activated T cells, has made it an alluring target for tumor immunotherapy. In contrast to immune checkpoint blocking antibodies, 4-1BB agonists can both potentiate anti-tumor and anti-viral immunity, while at the same time ameliorating autoimmune disease. Despite this, 4-1BB agonists can trigger high grade liver inflammation which has slowed their clinical development. In this review, we discuss how the underlying immunobiology of 4-1BB activation suggests the potential for therapeutically synergistic combination strategies in which immune adverse events can be minimized.