Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) regulates the unfolding of autoimmune diabetes

The Problem with Syngeneic Mouse Tumor Models

The advent of syngeneic mouse tumor models provided the scientific foundation for cancer immunotherapies now in widespread use. However, in many respects, these models do not faithfully recapitulate the interactions between cancer cells and the immune systems of human patients who have solid tumors because they represent a very early stage in the immune response to the newly transplanted cancer cells compared with the relatively mature stage found in human patients at the time of treatment. The lack of translatability of syngeneic models is probably responsible for many failed clinical trials conducted at considerable expense, involving far too many patients with cancer who received no benefit. Better mouse models would substantially accelerate the pace of discovery of new immunotherapies. Until these models emerge, a better understanding of the differences between the existing syngeneic models and human cancers may provide a more efficient path for moving experimental drugs into clinical development. To accomplish this, we must consider mice transplanted with syngeneic tumor cells to be in vivo assays, potentially useful for understanding the mechanism of action of immunotherapies rather than disease models.

Checkpoint Inhibitor-Induced Autoimmune Diabetes: An Autoinflammatory Disease

Immunomodulatory agents targeting immune checkpoints are now the state-of-the-art for the treatment of many cancers, but at the same time have led to autoimmune side effects, including autoimmune diabetes: immune checkpoint inhibitor-induced diabetes (CPI-DM). Emerging research shows the importance of preexisting autoimmune disease risk that has been identified through genetics, and autoantibodies. Key associated clinical findings also include increased levels of lipase before diagnosis suggesting that the inflammatory process in the pancreas extends beyond the islets of Langerhans. There is selectivity for the blockade of programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) for this adverse event, consistent with the role of this checkpoint in maintaining tolerance to autoimmune diabetes.

Establishment of CD8+ T Cell Thymic Central Tolerance to Tissue-Restricted Antigen Requires PD-1

Highly self-reactive T cells are censored from the repertoire by both central and peripheral tolerance mechanisms upon receipt of high-affinity TCR signals. Clonal deletion is considered a major driver of central tolerance; however, other mechanisms such as induction of regulatory T cells and functional impairment have been described. An understanding of the interplay between these different central tolerance mechanisms is still lacking. We previously showed that impaired clonal deletion to a model tissue-restricted Ag did not compromise tolerance. In this study, we determined that murine T cells that failed clonal deletion were rendered functionally impaired in the thymus. Programmed cell death protein 1 (PD-1) was induced in the thymus and was required to establish cell-intrinsic tolerance to tissue-restricted Ag in CD8+ thymocytes independently of clonal deletion. In bone marrow chimeras, tolerance was not observed in PD-L1-deficient recipients, but tolerance was largely maintained following adoptive transfer of tolerant thymocytes or T cells to PD-L1-deficient recipients. However, CRISPR-mediated ablation of PD-1 in tolerant T cells resulted in broken tolerance, suggesting different PD-1 signaling requirements for establishing versus maintaining tolerance. Finally, we showed that chronic exposure to high-affinity Ag supported the long-term maintenance of tolerance. Taken together, our study identifies a critical role for PD-1 in establishing central tolerance in autoreactive T cells that escape clonal deletion. It also sheds light on potential mechanisms of action of anti-PD-1 pathway immune checkpoint blockade and the development of immune-related adverse events.

Stocking the toolbox-Using preclinical models to understand the development and treatment of immune checkpoint inhibitor-induced immune-related adverse events

Cancer patients treated with immune checkpoint inhibitors (ICIs) are susceptible to a broad and variable array of immune-related adverse events (irAEs). With increasing clinical use of ICIs, defining the mechanism for irAE development is more critical than ever. However, it currently remains challenging to predict when these irAEs occur and which organ may be affected, and for many of the more severe irAEs, inaccessibility to the tissue site hampers mechanistic insight. This lack of understanding of irAE development in the clinical setting emphasizes the need for greater use of preclinical models that allow for improved prediction of biomarkers for ICI-initiated irAEs or that validate treatment options that inhibit irAEs without hampering the anti-tumor immune response. Here, we discuss the utility of preclinical models, ranging from exploring databases to in vivo animal models, focusing on where they are most useful and where they could be improved.

Endocrine immune-related adverse effects of immune-checkpoint inhibitors

INTRODUCTION

Immune-checkpoint inhibitor therapy modulates the response of the immune system acting against cancer. Two pathways impacted by this kind of treatment are the CTLA4 and the PD-1/PD-L1 pathways. ICI therapy can trigger autoimmune adverse effects, known as immune-related Adverse Events (irAEs).

AREAS COVERED

This review focuses on irAEs which affect the endocrine system. This review elucidates the pathways used by these drugs with a focus on the hypothetical pathogenesis at their basis. In fact, the pathophysiology of irAEs concerns the possibility of an interaction between cellular autoimmunity, humoral immunity, cytokines, chemokines, and genetics. The endocrine irAEs examined are thyroid dysfunctions, immune related-hypophysitis, diabetes, peripheral adrenal insufficiency, and hypoparathyroidism.

EXPERT OPINION

There is still much to investigate in endocrine irAES of checkpoint inhibitors. In the future, checkpoint inhibitors will be increasingly utilized therapies, and therefore it is crucial to find the proper diagnostic-therapeutic program for irAEs, especially as endocrine irAEs are nonreversible and require lifelong replacement therapies.

Immune-related adverse effects of checkpoint immunotherapy and implications for the treatment of patients with cancer and autoimmune diseases

During the past decade, there has been a revolution in cancer therapeutics by the emergence of antibody-based immunotherapies that modulate immune responses against tumors. These therapies have offered treatment options to patients who are no longer responding to classic anti-cancer therapies. By blocking inhibitory signals mediated by surface receptors that are naturally upregulated during activation of antigen-presenting cells (APC) and T cells, predominantly PD-1 and its ligand PD-L1, as well as CTLA-4, such blocking agents have revolutionized cancer treatment. However, breaking these inhibitory signals cannot be selectively targeted to the tumor microenvironment (TME). Since the physiologic role of these inhibitory receptors, known as immune checkpoints (IC) is to maintain peripheral tolerance by preventing the activation of autoreactive immune cells, IC inhibitors (ICI) induce multiple types of immune-related adverse effects (irAEs). These irAEs, together with the natural properties of ICs as gatekeepers of self-tolerance, have precluded the use of ICI in patients with pre-existing autoimmune diseases (ADs). However, currently accumulating data indicates that ICI might be safely administered to such patients. In this review, we discuss mechanisms of well established and newly recognized irAEs and evolving knowledge from the application of ICI therapies in patients with cancer and pre-existing ADs.

Metastatic lymph node targeted CTLA4 blockade: a potent intervention for local and distant metastases with minimal ICI-induced pneumonia

BACKGROUND

Immune checkpoint blockade (ICB) elicits a strong and durable therapeutic response, but its application is limited by disparate responses and its associated immune-related adverse events (irAEs). Previously, in a murine model of lymph node (LN) metastasis, we showed that intranodal administration of chemotherapeutic agents using a lymphatic drug delivery system (LDDS) elicits stronger therapeutic responses in comparison to systemic drug delivery approaches, while minimizing systemic toxicity, due to its improved pharmacokinetic profile at the intended site. Importantly, the LN is a reservoir of immunotherapeutic targets. We therefore hypothesized that metastatic LN-targeted ICB can amplify anti-tumor response and uncouple it from ICB-induced irAEs.

METHODS

To test our hypothesis, models of LN and distant metastases were established with luciferase expressing LM8 cells in MXH10/Mo-lpr/lpr mice, a recombinant inbred strain of mice capable of recapitulating ICB-induced interstitial pneumonia. This model was used to interrogate ICB-associated therapeutic response and immune related adverse events (irAEs) by in vivo imaging, high-frequency ultrasound imaging and histopathology. qPCR and flowcytometry were utilized to uncover the mediators of anti-tumor immunity.

RESULTS

Tumor-bearing LN (tbLN)-directed CTLA4 blockade generated robust anti-tumor response against local and systemic metastases, thereby improving survival. The anti-tumor effects were accompanied by an upregulation of effector CD8T cells in the tumor-microenvironment and periphery. In comparison, non-specific CTLA4 blockade was found to elicit weaker anti-tumor effect and exacerbated ICI-induced irAEs, especially interstitial pneumonia. Together these data highlight the importance of tbLN-targeted checkpoint blockade for efficacious response.

CONCLUSIONS

Intranodal delivery of immune checkpoint inhibitors to metastatic LN can potentiate therapeutic response while minimizing irAEs stemming from systemic lowering of immune activation threshold.

Autoimmunity: A New Focus on Nasal Polyps

Chronic rhinosinusitis with nasal polyps (CRSwNP) has long been considered a benign, chronic inflammatory, and hyperplastic disease. Recent studies have shown that autoimmune-related mechanisms are involved in the pathology of nasal polyps. Activated plasma cells, eosinophils, basophils, innate type 2 lymphocytes, mast cells, and proinflammatory cytokine in polyp tissue indicate the mobilization of innate and adaptive immune pathways during polyp formation. The discovery of a series of autoantibodies further supports the autoimmune nature of nasal polyps. Local homeostasis dysregulation, infection, and chronic inflammation may trigger autoimmunity through several mechanisms, including autoantigens overproduction, microbial translocation, molecular mimicry, superantigens, activation or inhibition of receptors, bystander activation, dysregulation of Toll-Like Receptors (TLRs), epitope spreading, autoantigens complementarity. In this paper, we elaborated on the microbiome-mediated mechanism, abnormal host immunity, and genetic changes to update the role of autoimmunity in the pathogenesis of chronic rhinosinusitis with nasal polyps.

Factors predisposing to humoral autoimmunity against brain-antigens in health and disease: Analysis of 49 autoantibodies in over 7000 subjects

BACKGROUND

Circulating autoantibodies (AB) against brain-antigens, often deemed pathological, receive increasing attention. We assessed predispositions and seroprevalence/characteristics of 49 AB in > 7000 individuals.

METHODS

Exploratory cross-sectional cohort study, investigating deeply phenotyped neuropsychiatric patients and healthy individuals of GRAS Data Collection for presence/characteristics of 49 brain-directed serum-AB. Predispositions were evaluated through GWAS of NMDAR1-AB carriers, analyses of immune check-point genotypes, APOE4 status, neurotrauma. Chi-square, Fisher's exact tests and logistic regression analyses were used.

RESULTS

Study of N = 7025 subjects (55.8 % male; 41 ± 16 years) revealed N = 1133 (16.13 %) carriers of any AB against 49 defined brain-antigens. Overall, age dependence of seroprevalence (OR = 1.018/year; 95 % CI [1.015-1.022]) emerged, but no disease association, neither general nor with neuropsychiatric subgroups. Males had higher AB seroprevalence (OR = 1.303; 95 % CI [1.144-1.486]). Immunoglobulin class (N for IgM:462; IgA:487; IgG:477) and titers were similar. Abundant were NMDAR1-AB (7.7 %). Low seroprevalence (1.25 %-0.02 %) was seen for most AB (e.g., amphiphysin, KCNA2, ARHGAP26, GFAP, CASPR2, MOG, Homer-3, KCNA1, GLRA1b, GAD65). Non-detectable were others. GWAS of NMDAR1-AB carriers revealed three genome-wide significant SNPs, two intergenic, one in TENM3, previously autoimmune disease-associated. Targeted analysis of immune check-point genotypes (CTLA4, PD1, PD-L1) uncovered effects on humoral anti-brain autoimmunity (OR = 1.55; 95 % CI [1.058-2.271]) and disease likelihood (OR = 1.43; 95 % CI [1.032-1.985]). APOE4 carriers (∼19 %) had lower seropositivity (OR = 0.766; 95 % CI [0.625-0.933]). Neurotrauma predisposed to NMDAR1-AB seroprevalence (IgM: OR = 1.599; 95 % CI [1.022-2.468]).

CONCLUSIONS

Humoral autoimmunity against brain-antigens, frequent across health and disease, is predicted by age, gender, genetic predisposition, and brain injury. Seroprevalence, immunoglobulin class, or titers do not predict disease.

Understanding the Mechanism of Diabetes Mellitus in a LRBA-Deficient Patient

The scope of this study is to show that DM in a LRBA-deficient patient with a stop codon mutation (c.3999 G > A) was not mediated through autoimmunity. We have evaluated the ability of the proband’s T cells to be activated by assessing their CTLA-4 expression. A nonsignificant difference was seen in the CTLA-4 expression on CD3+ T cells compared to the healthy control at basal level and after stimulation with PMA/ionomycin. Blood transcriptomic analysis have shown a remarkable increase in abundance of transcripts related to CD71+ erythroid cells. There were no differences in the expression of modules related to autoimmunity diseases between the proband and pooled healthy controls. In addition, our novel findings show that siRNA knockdown of LRBA in mouse pancreatic β-cells leads reduced cellular proinsulin, insulin and consequently insulin secretion, without change in cell viability in cultured MIN6 cells.

Neurologic Toxicity of Immune Checkpoint Inhibitors: A Review of Literature

Immune checkpoint inhibitors have entailed a change of paradigm in the management of multiple malignant diseases and are acquiring a key role in an increasing number of clinical sceneries. However, since their mechanism of action is not limited to the tumor microenvironment, their systemic activity may lead to a wide spectrum of immune-related side effects. Although neurological adverse events are much less frequent than gastrointestinal, hepatic, or lung toxicity, with an incidence of <5%, their potential severity and consequent interruptions to cancer treatment make them of particular importance. Despite them mainly implying peripheral neuropathies, immunotherapy has also been associated with an increased risk of encephalitis and paraneoplastic disorders affecting the central nervous system, often appearing in a clinical context where the appropriate diagnosis and early management of neuropsychiatric symptoms can be challenging. Although the pathogenesis of these complications is not fully understood yet, the blockade of tumoral inhibitory signals, and therefore the elicitation of cytotoxic T-cell-mediated response, seems to play a decisive role. The aim of this review was to summarize the current knowledge about the pathogenic mechanisms, clinical manifestations, and therapeutic recommendations regarding the main forms of neurotoxicity related to checkpoint inhibitors.

Conditional PD-1/PD-L1 Probody Therapeutics Induce Comparable Antitumor Immunity but Reduced Systemic Toxicity Compared with Traditional Anti-PD-1/PD-L1 Agents

Immune-checkpoint blockade has revolutionized cancer treatment. However, most patients do not respond to single-agent therapy. Combining checkpoint inhibitors with other immune-stimulating agents increases both efficacy and toxicity due to systemic T-cell activation. Protease-activatable antibody prodrugs, known as Probody therapeutics (Pb-Tx), localize antibody activity by attenuating capacity to bind antigen until protease activation in the tumor microenvironment. Herein, we show that systemic administration of anti-programmed cell death ligand 1 (anti-PD-L1) and anti-programmed cell death protein 1 (anti-PD-1) Pb-Tx to tumor-bearing mice elicited antitumor activity similar to that of traditional PD-1/PD-L1-targeted antibodies. Pb-Tx exhibited reduced systemic activity and an improved nonclinical safety profile, with markedly reduced target occupancy on peripheral T cells and reduced incidence of early-onset autoimmune diabetes in nonobese diabetic mice. Our results confirm that localized PD-1/PD-L1 inhibition by Pb-Tx can elicit robust antitumor immunity and minimize systemic immune-mediated toxicity. These data provide further preclinical rationale to support the ongoing development of the anti-PD-L1 Pb-Tx CX-072, which is currently in clinical trials.

MERTK on mononuclear phagocytes regulates T cell antigen recognition at autoimmune and tumor sites

Understanding mechanisms of immune regulation is key to developing immunotherapies for autoimmunity and cancer. We examined the role of mononuclear phagocytes during peripheral T cell regulation in type 1 diabetes and melanoma. MERTK expression and activity in mononuclear phagocytes in the pancreatic islets promoted islet T cell regulation, resulting in reduced sensitivity of T cell scanning for cognate antigen in prediabetic islets. MERTK-dependent regulation led to reduced T cell activation and effector function at the disease site in islets and prevented rapid progression of type 1 diabetes. In human islets, MERTK-expressing cells were increased in remaining insulin-containing islets of type 1 diabetic patients, suggesting that MERTK protects islets from autoimmune destruction. MERTK also regulated T cell arrest in melanoma tumors. These data indicate that MERTK signaling in mononuclear phagocytes drives T cell regulation at inflammatory disease sites in peripheral tissues through a mechanism that reduces the sensitivity of scanning for antigen leading to reduced responsiveness to antigen.

Cytotoxic T lymphocyte antigen-4 regulates development of xenogenic graft versus host disease in mice via modulation of host immune responses induced by changes in human T cell engraftment and gene expression

Graft versus host disease (GvHD) is a major clinical problem with a significant unmet medical need. We examined the role of cytotoxic T lymphocyte antigen-4 (CTLA-4) in a xenogenic GvHD (xeno-GvHD) model induced by injection of human peripheral mononuclear cells (hPBMC) into irradiated non-obese diabetic (NOD) SCID gamma (NSG) mice. Targeting the CTLA-4 pathway by treatment with CTLA-4 immunoglobulin (Ig) prevented xeno-GvHD, while anti-CTLA-4 antibody treatment exacerbated the lethality and morbidity associated with GvHD. Xeno-GvHD is associated with infiltration of hPBMCs into the lungs, spleen, stomach, liver and colon and an increase in human proinflammatory cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α and interleukin (IL)-5. Infiltration of donor cells and increases in cytokines were attenuated by treatment with CTLA-4 Ig, but remained either unaffected or enhanced by anti-CTLA-4 antibody. Further, splenic human T cell phenotyping showed that CTLA-4 Ig treatment prevented the engraftment of human CD45⁺ cells, while anti-CTLA-4 antibody enhanced donor T cell expansion, particularly CD4⁺ (CD45RO⁺ ) subsets, including T box transcription factor TBX21 (Tbet)⁺ CXCR3⁺ and CD25⁺ forkhead box protein 3 (FoxP3) cells. Comprehensive analysis of transcriptional profiling of human cells isolated from mouse spleen identified a set of 417 differentially expressed genes (DEGs) by CTLA-4 Ig treatment and 13 DEGs by anti-CTLA-4 antibody treatment. The CTLA-4 Ig regulated DEGs mapped to down-regulated apoptosis, inflammasome, T helper type 17 (Th17) and regulatory T cell (T_reg ) pathways and enhanced Toll-like receptor (TLR) receptor signaling, TNF family signaling, complement system and epigenetic and transcriptional regulation, whereas anti-CTLA-4 antibody produced minimal to no impact on these gene pathways. Our results show an important role of co-inhibitory CTLA-4 signaling in xeno-GvHD and suggest the therapeutic utility of other immune checkpoint co-inhibitory pathways in the treatment of immune-mediated diseases driven by hyperactive T cells.

Single-cell RNA sequencing of murine islets shows high cellular complexity at all stages of autoimmune diabetes

Tissue-specific autoimmune diseases are driven by activation of diverse immune cells in the target organs. However, the molecular signatures of immune cell populations over time in an autoimmune process remain poorly defined. Using single-cell RNA sequencing, we performed an unbiased examination of diverse islet-infiltrating cells during autoimmune diabetes in the nonobese diabetic mouse. The data revealed a landscape of transcriptional heterogeneity across the lymphoid and myeloid compartments. Memory CD4 and cytotoxic CD8 T cells appeared early in islets, accompanied by regulatory cells with distinct phenotypes. Surprisingly, we observed a dramatic remodeling in the islet microenvironment, in which the resident macrophages underwent a stepwise activation program. This process resulted in polarization of the macrophage subpopulations into a terminal proinflammatory state. This study provides a single-cell atlas defining the staging of autoimmune diabetes and reveals that diabetic autoimmunity is driven by transcriptionally distinct cell populations specialized in divergent biological functions.

The Role of T Cell Receptor Signaling in the Development of Type 1 Diabetes

T cell receptor (TCR) signaling influences multiple aspects of CD4⁺ and CD8⁺ T cell immunobiology including thymic development, peripheral homeostasis, effector subset differentiation/function, and memory formation. Additional T cell signaling cues triggered by co-stimulatory molecules and cytokines also affect TCR signaling duration, as well as accessory pathways that further shape a T cell response. Type 1 diabetes (T1D) is a T cell-driven autoimmune disease targeting the insulin producing β cells in the pancreas. Evidence indicates that dysregulated TCR signaling events in T1D impact the efficacy of central and peripheral tolerance-inducing mechanisms. In this review, we will discuss how the strength and nature of TCR signaling events influence the development of self-reactive T cells and drive the progression of T1D through effects on T cell gene expression, lineage commitment, and maintenance of pathogenic anti-self T cell effector function.

Neutrophil-Associated Inflammatory Changes in the Pre-Diabetic Pancreas of Early-Age NOD Mice

A growing body of evidence indicates that neutrophils are the first major leukocyte population accumulating inside the pancreas even before the onset of a lymphocytic-driven impairment of functional beta cells in type 1 diabetes mellitus (T1D). In humans, pancreata from T1D deceased donors exhibit significant neutrophil accumulation. We present a time course of previously unknown inflammatory changes that accompany neutrophil and neutrophil elastase accumulation in the pancreas of the non-obese diabetic (NOD) mouse strain as early as 2 weeks of age. We confirm earlier findings in NOD mice that neutrophils accumulate as early as 2 weeks of age. We also observe a concurrent increase in the expression of neutrophil elastase in this time period. We also detect components of neutrophil extracellular traps (NET) mainly in the exocrine tissue of the pancreas during this time as well as markers of vascular pathology as early as 2 weeks of age. Age- and sex-matched C57BL/6 mice do not exhibit these features inside the pancreas. When we treated NOD mice with inhibitors of myeloperoxidase and neutrophil elastase, two key effectors of activated neutrophil activity, alone or in combination, we were unable to prevent the progression to hyperglycemia in any manner different from untreated control mice. Our data confirm and add to the body of evidence demonstrating neutrophil accumulation inside the pancreas of mice genetically susceptible to T1D and also offer novel insights into additional pathologic mechanisms involving the pancreatic vasculature that have, until now, not been discovered inside the pancreata of these mice. However, inhibition of key neutrophil enzymes expressed in activated neutrophils could not prevent diabetes. These findings add to the body of data supporting a role for neutrophils in the establishment of early pathology inside the pancreas, independently of, and earlier from the time at onset of lymphocytic infiltration. However, they also suggest that inhibition of neutrophils alone, acting via myeloperoxidase and neutrophil elastase only, in the absence of other other effector cells, is insufficient to alter the natural course of autoimmune diabetes, at least in the NOD model of the disease.

Multiple inducers and novel roles of autoantibodies against the obligatory NMDAR subunit NR1: a translational study from chronic life stress to brain injury

Circulating autoantibodies (AB) of different immunoglobulin classes (IgM, IgA, and IgG), directed against the obligatory N-methyl-D-aspartate-receptor subunit NR1 (NMDAR1-AB), belong to the mammalian autoimmune repertoire, and appear with age-dependently high seroprevalence across health and disease. Upon access to the brain, they can exert NMDAR-antagonistic/ketamine-like actions. Still unanswered key questions, addressed here, are conditions of NMDAR1-AB formation/boosting, intraindividual persistence/course in serum over time, and (patho)physiological significance of NMDAR1-AB in modulating neuropsychiatric phenotypes. We demonstrate in a translational fashion from mouse to human that (1) serum NMDAR1-AB fluctuate upon long-term observation, independent of blood-brain barrier (BBB) perturbation; (2) a standardized small brain lesion in juvenile mice leads to increased NMDAR1-AB seroprevalence (IgM + IgG), together with enhanced Ig-class diversity; (3) CTLA4 (immune-checkpoint) genotypes, previously found associated with autoimmune disease, predispose to serum NMDAR1-AB in humans; (4) finally, pursuing our prior findings of an early increase in NMDAR1-AB seroprevalence in human migrants, which implicated chronic life stress as inducer, we independently replicate these results with prospectively recruited refugee minors. Most importantly, we here provide the first experimental evidence in mice of chronic life stress promoting serum NMDAR1-AB (IgA). Strikingly, stress-induced depressive-like behavior in mice and depression/anxiety in humans are reduced in NMDAR1-AB carriers with compromised BBB where NMDAR1-AB can readily reach the brain. To conclude, NMDAR1-AB may have a role as endogenous NMDAR antagonists, formed or boosted under various circumstances, ranging from genetic predisposition to, e.g., tumors, infection, brain injury, and stress, altogether increasing over lifetime, and exerting a spectrum of possible effects, also including beneficial functions.

Predictive Biomarkers of Immune Checkpoint Inhibitors-Related Toxicities

The emergence and continuous development of immune checkpoint inhibitors (ICIs) therapy brings a revolution in cancer therapy history, but the major hurdle associated with their usage is the concomitant ICIs-related toxicities that present a challenge for oncologists. The toxicities may involve non-specific symptoms of multiple systems as for the unique mechanism of formation, which are not easily distinguishable from traditional toxicities. A few of these adverse events are self-limiting and readily manageable, but others may limit treatment, cause interruption and need to be treated with methylprednisolone or tumor necrosis factor-α (TNF-α) antibody infliximab, and even directly threaten life. Early accurate recognition and adequate management are critical to the patient's prognosis and overall survival (OS). Several biomarkers such as the expression of programmed cell death ligand 1 (PD-L1), tumor mutation burden (TMB), and microsatellite instability-high (MSI-H)/mismatch repair-deficient (dMMR) have been proved to be the predictors for anti-tumor efficacy of ICIs, but there is a gap in clinical needs for effective biomarkers that predict toxicities and help filter out the patients who may benefit most from these costly therapies while avoiding major risks of toxicities. Here, we summarize several types of risk factors correlated with ICIs-related toxicities to provide a reference for oncologists to predict the occurrence of ICIs-related toxicities resulting in a timely process in clinical practice.

Autoimmune Endocrinopathies: An Emerging Complication of Immune Checkpoint Inhibitors

Immune checkpoint inhibitors (CPIs) reverse immune suppression that is thought to allow malignant growth. Despite remarkable efficacy in a subset of cancers, their use is accompanied by immune-related adverse events, including endocrinopathies such as hypophysitis, thyroid dysfunction, diabetes, and adrenalitis. These conditions are heterogenous, with differing incidence across CPI types, but are unified by the acuity and extremity of tissue-specific organ failure. Their occurrence may be associated with beneficial tumor control. Further understanding of the risk factors and mechanisms of these endocrine immunotoxicities can help optimize CPI use as well as improve understanding of spontaneous autoimmune diseases.

Immune-Driven Pathogenesis of Neurotoxicity after Exposure of Cancer Patients to Immune Checkpoint Inhibitors

Over the last decade, immune checkpoint inhibitors (ICIs) have revolutionized the treatment of several cancer types. ICIs work through the blockage of immune inhibitory signals, while increasing the T-cell specific immune antitumoral response. However, due to the fact that ICIs’ mechanism of action is not tissue antigen-specific and not limited to the tumor microenvironment, the use of cancer immunotherapy can produce a broad range of immune-related adverse events (irAEs). Neurological immune-related adverse events (NirAEs) are rare (the overall incidence varies between 1% to 6%), and these adverse events mainly concern the peripheral nervous system, rather than the central nervous system. Due to their potential severity, which could cause interruptions to cancer treatment, NirAEs are of particular clinical importance. Currently, the pathogenesis of these complications is not completely understood, although T-cells seem to play a principal role. Nevertheless, the development of NirAEs is likely to be a multifactorial and complex process. This conclusion can be extracted from the wide range of neurological auto-inflammatory and autoimmune disorders triggered or exacerbated by ICIs, and the extensive variability of the limited histological findings reported. The aim of this review is to summarize the potential immune-driven pathological mechanisms of NirAEs.

Inhibitory receptor agonists: the future of autoimmune disease therapeutics?

Central and peripheral tolerance both contribute to protection against autoimmunity. The pathogenesis of autoimmunity, however, can result from critical deficits or limitations in peripheral and/or central tolerance mechanisms, presenting an opportunity for therapeutic intervention. Recent advances highlight the substantial impact of inhibitory receptors (IRs), which mediate peripheral tolerance, in autoimmunity. Deletion and blockade studies in mice, IR disruption in humans, and correlation with positive disease outcomes all highlight potential clinical benefits of enhancing IR signaling (agonism)-specifically CTLA4, PD1, LAG3, TIM3 and TIGIT-to treat autoimmune disease. Although critical questions remain, IR agonists represent an unappreciated and untapped opportunity for the treatment of autoimmune and inflammatory diseases.

Immune checkpoint inhibitor diabetes mellitus: a novel form of autoimmune diabetes

Autoimmune diabetes mellitus is a rare but significant side effect of treatment with immune checkpoint inhibitors. Immune checkpoint inhibitor-induced diabetes mellitus (CPI-DM) is characterized by acute onset of dramatic hyperglycemia with severe insulin deficiency and occurrence following exposure to programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) inhibitors rather than cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) inhibitors. As a growing number of patients undergo immunotherapy, further understanding of the characteristics of CPI-DM patients is needed for improved prognostic and diagnostic application in order to reduce overall morbidity for this already at-risk population. Additionally, understanding of the features and mechanisms of CPI-DM may contribute to understanding mechanisms of spontaneous type I diabetes mellitus (T1DM). Here, we summarize the clinical features of CPI-DM and interrogate the genetic and cellular mechanisms that may contribute to the disease, as well as the clinical challenges for predicting and treating these patients as increasing cancer immunotherapies reach clinical utility.

The yin and yang of co-inhibitory receptors: toward anti-tumor immunity without autoimmunity

Co-inhibitory receptors are important regulators of T-cell function that define the balance between tolerance and autoimmunity. The immune regulatory function of co-inhibitory receptors, including CTLA-4, PD-1, TIM-3, TIGIT, and LAG-3, was first discovered in the setting of autoimmune disease models, in which their blockade or deficiency resulted in induction or exacerbation of the disease. Later on, co-inhibitory receptors on lymphocytes have also been found to influence outcomes in tumor and chronic viral infection settings. These receptors suppress T-cell function in the tumor microenvironment (TME), thereby making the T cells dysfunctional. Based on this observation, blockade of co-inhibitory receptors (also known as checkpoint molecules) has emerged as a successful treatment option for a number of human cancers. However, severe autoimmune-like side effects limit the use of therapeutics that block individual or combinations of co-inhibitory receptors for cancer treatment. In this review we provide an overview of the role of co-inhibitory receptors in autoimmunity and anti-tumor immunity. We then discuss current approaches and future directions to leverage our knowledge of co-inhibitory receptors to target them in tumor immunity without inducing autoimmunity.

Type 1 diabetes pathogenesis and the role of inhibitory receptors in islet tolerance

Type 1 diabetes (T1D) affects over a million Americans, and disease incidence is on the rise. Despite decades of research, there is still no cure for this disease. Exciting beta cell replacement strategies are being developed, but in order for such approaches to work, targeted immunotherapies must be designed. To selectively halt the autoimmune response, researchers must first understand how this response is regulated and which tolerance checkpoints fail during T1D development. Herein, we discuss the current understanding of T1D pathogenesis in humans, genetic and environmental risk factors, presumed roles of CD4+ and CD8+ T cells as well as B cells, and implicated autoantigens. We also highlight studies in non-obese diabetic mice that have demonstrated the requirement for CD4+ and CD8+ T cells and B cells in driving T1D pathology. We present an overview of central and peripheral tolerance mechanisms and comment on existing controversies in the field regarding central tolerance. Finally, we discuss T cell- and B cell-intrinsic tolerance mechanisms, with an emphasis on the roles of inhibitory receptors in maintaining islet tolerance in humans and in diabetes-prone mice, and strategies employed to date to harness inhibitory receptor signaling to prevent or reverse T1D.

Toxicity of tumor immune checkpoint inhibitors-more attention should be paid

In recent years, immunotherapy, especially immune checkpoint inhibitors (ICIs), has achieved amazing results in the treatment of lung cancer, melanoma, renal clear cell carcinoma and other malignant tumors. Although ICIs have achieved significant efficacy in tumor treatment, the immune-related adverse events (irAEs) caused by non-specific immune activation of ICIs can directly affect the result of treatment, even threaten the life of patients. The most common form of irAEs involve the skin, lung, colon, liver and endocrine organs. However, it is noticeable that although irAEs of some organs are more common, actually any organ and tissue are likely to be affected, because of non-specific activation of the immune system. Other tissues and organs, though rare, can be more severe and even fatal, such as neurological disorders and myocarditis. Therefore, effective management of irAEs is of great importance for the efficacy of immunotherapy. This review is focused on the morbidity, clinical manifestations, diagnosis and treatment of tumor immune toxic effects.

Autoimmune complications of cancer immunotherapy

Immunotherapy of cancer with blockade of inhibitory immune checkpoints and adoptive cell therapies have led to impressive clinical responses in several cancers. However, with increasing utilization of these therapies, immune-related adverse events have emerged as a major obstacle. Herein I discuss recent insights into the immunobiology of these toxicities. Deeper understanding of the underlying pathogenic mechanisms, cellular and molecular pathways involved, similarities and differences with spontaneous autoimmunity, and identification of clinically relevant predictive biomarkers is needed to develop optimal approaches to prevent and treat these toxicities, without compromising the therapeutic benefit from these immune therapies. These events may also provide a unique window into mechanisms underlying spontaneous autoimmunity.

A Model for Apoptotic-Cell-Mediated Adaptive Immune Evasion via CD80-CTLA-4 Signaling

Apoptotic cells carry a plethora of self-antigens but they suppress eliciting of innate and adaptive immune responses to them. How apoptotic cells evade and subvert adaptive immune responses has been elusive. Here, we propose a novel model to understand how apoptotic cells regulate T cell activation in different contexts, leading mostly to tolerogenic responses, mainly via taking control of the CD80-CTLA-4 coinhibitory signal delivered to T cells. This model may facilitate understanding of the molecular mechanisms of autoimmune diseases associated with dysregulation of apoptosis or apoptotic cell clearance, and it highlights potential therapeutic targets or strategies for treatment of multiple immunological disorders.

Constitutive reduction in the checkpoint inhibitor, CTLA-4, does not accelerate SLE in NZM 2328 mice

Background/objective

Treatment with immune checkpoint inhibitors (ICIs) in oncology patients is increasing. Although ICIs trigger rheumatic immune-related adverse events, development of SLE features has been rare. Whether long-term treatment with ICIs would promote SLE features remains unknown. To begin to address this, we generated SLE-prone NZM 2328 mice with lifelong reduction in CTLA-4 expression.

Methods

Since CTLA-4-deficient (Ctla4^−/−) NZM mice developed a lethal lymphoproliferative disorder by 3–6 weeks of age, development of SLE in these mice could not be studied. Ctla4 haploinsufficient NZM.Ctla4^+/− mice were assessed in parallel with littermate female NZM.Ctla4^+/+ mice. Evaluations included CTLA-4 expression and lymphocyte profiles, assessed by fluorescence-activated cell sorting; serological profiles, assessed by ELISA; renal immunopathology, assessed by histology and immunofluorescence; and clinical courses, assessed by mortality.

Results

CTLA-4 expression was lower in NZM.Ctla4^+/− mice than in NZM.Ctla4^+/+ mice. Spleen mononuclear cells, B cells, plasma cells, CD4⁺ cells, recently activated CD4⁺ cells and CD4⁺ T regulatory (Treg) cells were increased in NZM.Ctla4^+/− mice (p≤0.042). The serological profile, degree of renal immunopathology and mortality in NZM.Ctla4^+/− mice remained unaffected.

Conclusion

Lifelong reduction in CTLA-4 expression in NZM mice neither accelerated nor aggravated SLE. Expansion in Treg cells may have played a protective role. Our observations raise the hope that long-term treatment of patients with SLE with an anti-CTLA-4 agent, should the need arise, would not adversely affect SLE disease activity.

The Balancing Act between Cancer Immunity and Autoimmunity in Response to Immunotherapy

The explosion in novel cancer immunotherapies has resulted in extraordinary clinical successes in the treatment of multiple cancers. Checkpoint inhibitors (CPIs) that target negative regulatory molecules have become standard of care. However, with the growing use of CPIs, alone or in combination with chemotherapy, targeted therapies, or other immune modulators, a significant increase in immune-related adverse events (irAEs) has emerged. The wide-ranging and currently unpredictable spectrum of CPI-induced irAEs can lead to profound pathology and, in some cases, death. Growing evidence indicates that many irAEs are a consequence of a breakdown in self-tolerance, but the influence of genetics, the environment, and the mechanisms involved remains unclear. This review explores key questions in this emerging field, summarizing preclinical and clinical experiences with this new generation of cancer drugs, the growing understanding of the role of the immune response in mediating these toxicities, the relationship of CPI-induced autoimmunity to conventional autoimmune diseases, and insights into the mechanism of irAE development and treatment.

The Yin and Yang of Myeloid Derived Suppressor Cells

In recent years, most of our knowledge about myeloid derived suppressor cells (MDSCs) has come from cancer studies, which depicts Yin side of MDSCs. In cancer, inherent immunosuppressive action of MDSCs favors tumor progression by inhibiting antitumor immune response. However, recently Yang side of MDSCs has also been worked out and suggests the role in maintenance of homeostasis during non-cancer situations like pregnancy, obesity, diabetes, and autoimmune disorders. Continued work in this area has armored the biological importance of these cells as master regulators of immune system and prompted scientists all over the world to look from a different perspective. Therefore, explicating Yin and Yang arms of MDSCs is obligatory to use it as a double edged sword in a much smarter way. This review is an attempt toward presenting a synergistic coalition of all the facts and controversies that exist in understanding MDSCs, bring them on the same platform and approach their "Yin and Yang" nature in a more comprehensive and coherent manner.

Selective CD28 Inhibition Modulates Alloimmunity and Cardiac Allograft Vasculopathy in Anti-CD154-Treated Monkeys

BACKGROUND

Selective CD28 inhibition is actively pursued as an alternative to B7 blockade using cytotoxic T lymphocyte antigen 4 Ig based on the hypothesis that the checkpoint immune regulators cytotoxic T lymphocyte antigen 4 and programmed death ligand 1 will induce tolerogenic immune signals. We previously showed that blocking CD28 using a monovalent nonactivating reagent (single-chain anti-CD28 Fv fragment linked to alpha-1 antitrypsin [sc28AT]) synergizes with calcineurin inhibitors in nonhuman primate (NHP) kidney and heart transplantation. Here, we explored the efficacy of combining a 3-week "induction" sc28AT treatment with prolonged CD154 blockade.

METHODS

Cynomolgus monkey heterotopic cardiac allograft recipients received sc28AT (10 mg/kg, d0-20, n = 3), hu5C8 (10-30 mg/kg, d0-84, n = 4), or combination (n = 6). Graft survival was monitored by telemetry. Protocol biopsies and graft explants were analyzed for International Society of Heart and Lung Transplantation acute rejection grade and cardiac allograft vasculopathy score. Alloantibody, T-cell phenotype and regulatory T cells were analyzed by flow cytometry. Immunochemistry and gene expression (NanoString) characterized intra-graft cellular infiltration.

RESULTS

Relative to modest prolongation of median graft survival time with sc28AT alone (34 days), hu5C8 (133 days), and sc28AT + hu5C8 (141 days) prolonged survival to a similar extent. CD28 blockade at induction, added to hu5C8, significantly attenuated the severity of acute rejection and cardiac allograft vasculopathy during the first 3 months after transplantation relative to hu5C8 alone. These findings were associated with decreased proportions of circulating CD8 and CD3CD28 T cells, and modulation of inflammatory gene expression within allografts.

CONCLUSIONS

Induction with sc28AT promotes early cardiac allograft protection in hu5C8-treated NHPs. These results support further investigation of prolonged selective CD28 inhibition with CD40/CD154 blockade in NHP transplants.

Regulatory T Cell-Mediated Tissue Repair

Regulatory T-cells (Treg cells) are a specific group of T-cells that maintain immune homeostasis by counteracting the immune responses of conventional T-cells. So far, the therapeutic applications of Treg cells have focused on the treatment of autoimmune diseases, as depletion of Treg cells or Treg-related genes is known to cause autoimmune defects. However, Treg cells can be a potential solution for tissue repair as they can terminate the pro-inflammatory phase and initiate the anti-inflammatory or regenerative phase at the tissue injury site. This review summarizes the known characteristics of Treg cells and lists examples of their therapeutic applications. The use of Treg cells in the treatment of myocardial infarctions, skeletal muscle injuries, and ischemia injuries has revealed their potential as a promising tissue repair method. We have also discussed the limitations and scope of Treg cells in tissue repair.

Co-stimulatory and Co-inhibitory Pathways in Autoimmunity

The immune system is guided by a series of checks and balances, a major component of which is a large array of co-stimulatory and co-inhibitory pathways that modulate the host response. Although co-stimulation is essential for boosting and shaping the initial response following signaling through the antigen receptor, inhibitory pathways are also critical for modulating the immune response. Excessive co-stimulation and/or insufficient co-inhibition can lead to a breakdown of self-tolerance and thus to autoimmunity. In this review, we will focus on the role of co-stimulatory and co-inhibitory pathways in two systemic (systemic lupus erythematosus and rheumatoid arthritis) and two organ-specific (multiple sclerosis and type 1 diabetes) emblematic autoimmune diseases. We will also discuss how mechanistic analysis of these pathways has led to the identification of potential therapeutic targets and initiation of clinical trials for autoimmune diseases, as well as outline some of the challenges that lie ahead.

Is autoimmunity the Achilles' heel of cancer immunotherapy?

The emergence of immuno-oncology as the first broadly successful strategy for metastatic cancer will require clinicians to integrate this new pillar of medicine with chemotherapy, radiation, and targeted small-molecule compounds. Of equal importance is gaining an understanding of the limitations and toxicities of immunotherapy. Immunotherapy was initially perceived to be a relatively less toxic approach to cancer treatment than other available therapies-and surely it is, when compared to those. However, as the use of immunotherapy becomes more common, especially as first- and second-line treatments, immunotoxicity and autoimmunity are emerging as the Achilles' heel of immunotherapy. In this Perspective, we discuss evidence that the occurrence of immunotoxicity bodes well for the patient, and describe mechanisms that might be related to the induction of autoimmunity. We then explore approaches to limit immunotoxicity, and discuss the future directions of research and reporting that are needed to diminish it.

Regulatory T cells in multiple sclerosis and myasthenia gravis

Multiple sclerosis (MS) is a chronic debilitating disease of the central nervous system primarily mediated by T lymphocytes with specificity to neuronal antigens in genetically susceptible individuals. On the other hand, myasthenia gravis (MG) primarily involves destruction of the neuromuscular junction by antibodies specific to the acetylcholine receptor. Both autoimmune diseases are thought to result from loss of self-tolerance, which allows for the development and function of autoreactive lymphocytes. Although the mechanisms underlying compromised self-tolerance in these and other autoimmune diseases have not been fully elucidated, one possibility is numerical, functional, and/or migratory deficits in T regulatory cells (Tregs). Tregs are thought to play a critical role in the maintenance of peripheral immune tolerance. It is believed that Tregs function by suppressing the effector CD4+ T cell subsets that mediate autoimmune responses. Dysregulation of suppressive and migratory markers on Tregs have been linked to the pathogenesis of both MS and MG. For example, genetic abnormalities have been found in Treg suppressive markers CTLA-4 and CD25, while others have shown a decreased expression of FoxP3 and IL-10. Furthermore, elevated levels of pro-inflammatory cytokines such as IL-6, IL-17, and IFN-γ secreted by T effectors have been noted in MS and MG patients. This review provides several strategies of treatment which have been shown to be effective or are proposed as potential therapies to restore the function of various Treg subsets including Tr1, iTr35, nTregs, and iTregs. Strategies focusing on enhancing the Treg function find importance in cytokines TGF-β, IDO, interleukins 10, 27, and 35, and ligands Jagged-1 and OX40L. Likewise, strategies which affect Treg migration involve chemokines CCL17 and CXCL11. In pre-clinical animal models of experimental autoimmune encephalomyelitis (EAE) and experimental autoimmune myasthenia gravis (EAMG), several strategies have been shown to ameliorate the disease and thus appear promising for treating patients with MS or MG.

Escherichia coli Heat-Labile Enterotoxin B Limits T Cells Activation by Promoting Immature Dendritic Cells and Enhancing Regulatory T Cell Function

Treatments to limit T cell activation are essential for managing autoimmune and inflammatory disorders. The B subunit of Escherichia coli heat-labile enterotoxin (EtxB) is known to ameliorate inflammatory disease in vivo but the mechanism by which this is mediated is not well understood. Here, we show that following intranasal administration, EtxB acts on two key cellular regulators of T cell activation: regulatory T cells and dendritic cells (DCs). EtxB enhances the proliferation of lung regulatory T cells and doubles their suppressive function, likely through an increase in expression of the Treg effector molecule CTLA-4. EtxB supports the generation of interleukin-10-producing DCs that are unable to activate T cells. These data show, for the first time, that mucosal EtxB treatment limits T cells activation by acting jointly on two distinct types of immune cells.

Glucocorticoids did not reverse type 1 diabetes mellitus secondary to pembrolizumab in a patient with metastatic melanoma

Immune checkpoint inhibitors offer patients with advanced melanoma substantial improvements in survival. Unlike chemotherapy, immune checkpoint inhibitors such as ipilimumab and pembrolizumab cause unique immune-related adverse events (irAEs), including the development of endocrinopathies. We report a case of a man aged 60 years who developed diabetic ketoacidosis (DKA) following the use of pembrolizumab for the treatment of metastatic melanoma. He received four cycles of ipilimumab, before proceeding to pembrolizumab. Five weeks after initiating pembrolizumab, he presented in DKA with a pH of 7.0, bicarbonate of 7 mmol/L, blood glucose of 27 mmol/L and serum ketones of 5.9 mmol/L. Antibodies to glutamic acid decarboxylase (anti-GAD) and Islet antigen 2 (IA-2) were negative and C-peptide was low at 57 pmol/L (300-2350 pmol/L). There was no personal or family history of autoimmune conditions. Standard immunosuppression for irAEs was started using prednisolone in an attempt to salvage β cell function but was unsuccessful. To the best of our knowledge, this is the first reported attempt at reversing pembrolizumab-induced type 1 diabetes using glucocorticoids.

Monitoring and Management of Immune-Related Adverse Events Associated With Programmed Cell Death Protein-1 Axis Inhibitors in Lung Cancer

Monoclonal antibodies targeting programmed cell death protein-1 (PD-1) represent a new treatment paradigm in non-small cell lung cancer. Three phase III trials have demonstrated a survival benefit and improved tolerability of nivolumab and pembrolizumab when compared with standard second-line chemotherapy. Nevertheless, the adverse events associated with PD-1 inhibitors are unique; early recognition and treatment are essential. This review summarizes the required monitoring and appropriate management of immune-related adverse events in lung cancer patients receiving these agents.

THE ONCOLOGIST

2017;22:70-80 IMPLICATIONS FOR PRACTICE: : The potential adverse events of immune checkpoint inhibitors differ from conventional chemotherapy and can require a multidisciplinary approach. Continued education is important for all physicians to ensure optimal care for patients.

Ipilimumab (Anti-Ctla-4 Mab) in the treatment of metastatic melanoma: Effectiveness and toxicity management

In the last years the onset of new therapies changed the management of malignant melanoma. Anti CTLA-4 antibody ipilimumab was the first drug to achieve a significant improvement in survival of advanced stage melanoma. This new therapeutic agent is characterized by a number of side effects that are totally different from those of traditional chemotherapy, mainly caused by the immune system activation. The purpose of this paper is to underline the central role of ipilimumab in the treatment of metastatic melanoma and to characterize related adverse events in terms of incidence, duration and severity of presentation. The early recognition of these side effects is crucial in order to ensure an appropriate management of the toxicities, thus reducing the long term clinical sequelae and the inappropriate treatment discontinuation.

Managing immune checkpoint-blocking antibody side effects

Immune checkpoint-blocking antibodies that enhance the immune system's ability to fight cancer are becoming important components of treatment for patients with a variety of malignancies. Cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) was the first immune checkpoint to be clinically targeted, and ipilimumab, an inhibitor of CTLA-4, was approved by the U.S. Food and Drug Administration (FDA) for patients with advanced melanoma. The programmed cell death-1 (PD-1) receptor and one of its ligands, PD-L1, more recently have shown great promise as therapeutic targets in a variety of malignancies. Nivolumab and pembrolizumab recently have been FDA- approved for patients with melanoma and additional approvals within this therapeutic class are expected. The use of anti-CTLA-4 and anti-PD-1/PD-L1 antibodies is associated with side effects known as immune-related adverse events (irAEs). Immune-related adverse events affect the dermatologic, gastrointestinal, hepatic, endocrine, and other organ systems. Temporary immunosuppression with corticosteroids, tumor necrosis factor-alpha antagonists, mycophenolate mofetil, or other agents can be effective treatment. This article describes the side-effect profile of the checkpoint-blocking antibodies that target CTLA-4 and PD-1/PD-L1 and provides suggestions on how to manage specific irAEs.

Autoimmune Diabetes: An Overview of Experimental Models and Novel Therapeutics

Type 1 diabetes (T1D) results from a chronic and selective destruction of insulin-secreting β-cells within the islets of Langerhans of the pancreas by autoreactive CD4(+) and CD8(+) T lymphocytes. The use of animal models of T1D was instrumental for deciphering the steps of the autoimmune process leading to T1D. The non-obese diabetic (NOD) mouse and the bio-breeding (BB) rat spontaneously develop the disease similar to the human pathology in terms of the immune responses triggering autoimmune diabetes and of the genetic and environmental factors influencing disease susceptibility. The generation of genetically modified models allowed refining our understanding of the etiology and the pathogenesis of the disease. In the present review, we provide an overview of the experimental models generated and used to gain knowledge on the molecular and cellular mechanisms underlying the breakdown of self-tolerance in T1D and the progression of the autoimmune response. Immunotherapeutic interventions designed in these animal models and translated into the clinical arena in T1D patients will also be discussed.

New toxicity profile for novel immunotherapy agents: focus on immune-checkpoint inhibitors

INTRODUCTION

Tumor development results from a cancer-induced immunosuppression (immune-editing). Immunotherapy has revolutionized the treatment paradigm for many malignancies, putting clinicians before novel toxicities, of immune-mediated etiology (immune-related adverse events).

AREAS COVERED

Immune-mediated toxicity depends on both innate and adaptive immunity mechanisms. Healthy tissue damage depends on an aspecific T-cell hyperactivation response causing cross-reaction with normal tissues, which leads to an overproduction of CD4 T-helper cell cytokines and an abnormal migration of cytolytic CD8 T-cells. By stimulating a diffuse T-cell repertoire expansion, immune-checkpoint inhibitors counteract tumor growth but reduce the self-tolerance, damaging healthy organs. In this review, we summarize the toxicity profile of the novel immune-checkpoint inhibitors and their clinical implications, we are convinced that a deep understanding and a prompt resolution of the paradigmatic toxicities of these drugs will result in clinical benefits to patients and an enhanced antitumor effect.

EXPERT OPINION

A focus on immunotoxicity is important in the education of clinicians and will improve patient safety. There is a willingness to tailor specific immune-therapies to each cancer patient, and to stimulate researchers through understanding of the physiopathogenesis, using the hypothesis that immune-mediated toxicities can be used as predictors of response or a prognostic sign of survival, thereby guiding therapeutic decisions.

Toxicities of the anti-PD-1 and anti-PD-L1 immune checkpoint antibodies

Immune checkpoint antibodies that augment the programmed cell death protein 1 (PD-1)/PD-L1 pathway have demonstrated antitumor activity across multiple malignancies, and gained recent regulatory approval as single-agent therapy for the treatment of metastatic malignant melanoma and nonsmall-cell lung cancer. Knowledge of toxicities associated with PD-1/PD-L1 blockade, as well as effective management algorithms for these toxicities, is pivotal in order to optimize clinical efficacy and safety. In this article, we review selected published and presented clinical studies investigating single-agent anti-PD-1/PD-L1 therapy and trials of combination approaches with other standard anticancer therapies, in multiple tumor types. We summarize the key adverse events reported in these studies and their management algorithms.