PD-1 pathway-mediated regulation of islet-specific CD4+ T cell subsets in autoimmune diabetes

Toxicity profile of camrelizumab-based immunotherapy in older adults with advanced cancer

Immune checkpoint inhibitors (ICIs) have become an important cornerstone of many tumour treatments. However, the toxicity profile of immune-chemotherapy combination treatment approaches among older adult cancer patients is still unclear. Patients with any cancer who received camrelizumab-based immunotherapy were eligible for inclusion. The primary endpoints were adverse events (AEs) and immune-related adverse events (irAEs), which were defined based on Naranjo's algorithm. Patients were stratified by age (≥ 70 years and < 70 years), and comparisons were made based on the type of camrelizumab-based therapy (monotherapy, combined chemotherapy, or combined anti-VEGF therapy). A total of 185 patients were administered camrelizumab-based immunotherapy, 55 (30%) of whom were ≥ 70 years old. A total of 146 (78.9%) patients received camrelizumab-based combination treatment. The incidence of all-grade AEs was 56.8% (105 patients), while that of irAEs was 36.8% (68 patients). There was no difference in the percentage of patients experiencing any grade or grade ≥ 3 AEs between age groups. However, the frequency of irAEs (both any grade and grade ≥ 3) significantly differed by age group (P = 0.001 and 0.009, respectively). The results of multivariable analysis revealed that age ≥ 70 years was the only independent risk factor for irAEs. The results of subgroup analysis revealed that the incidence of irAEs was higher in older patients treated with camrelizumab-chemotherapy, while the incidence rates were similar between age groups in the monotherapy and combination anti-VEGF treatment subgroups. Immune-related diabetes mellitus occurred more frequently among older adults. The spectrum of irAEs showed that combination immunotherapy had more widely effects on the organ system than monotherapy. In this study, older (≥ 70 years) patients had a higher risk of all-grade and high-grade irAEs when receiving camrelizumab chemotherapy combination treatment. Notably, long-term random glucose monitoring should be performed during ICI-based immunotherapy in older cancer patients.

Flash Glucose Monitoring and Diabetes Mellitus Induced by Immune Checkpoint Inhibitors: An Approach to Clinical Practice

OBJECTIVES

The aim of this study is to investigate in depth diabetes mellitus associated with immune checkpoint inhibitors (DM-ICIs) by analysing a case series. We also evaluated the clinical impact of flash glucose monitoring (FGM) systems in the management of this entity.

METHODS

We conducted an observational cohort study of DM-ICIs diagnosed in two hospitals in Seville (Spain). Patients with a new diagnosis of diabetes mellitus (DM) or with sudden worsening of preexisting DM after starting treatment with ICIs, with a random 5 hour-postprandial C-peptide value of <0.6 nmol/L and without possibility of subsequent withdrawal of insulin treatment, were included.

RESULTS

A total of 7 cases were identified, mostly males (n = 6; 85.7%), with a mean age of 64.9 years. The mean glycated hemoglobin (HbA1c) upon diagnosis was 8.1%, with diabetic ketoacidosis (DKA) observed in 6 cases (85.7%). Subcutaneous flash glucose monitoring (FGM) systems were used in six cases, with a mean follow-up period of 42.7 weeks. During the first 90 days of use, mean average glucose was 167.5 mg/dL, with a coefficient of variation (CV) of 34.6%. The mean time in the range 70-180 mg/dL (TIR) was 59.7%, with a mean time above range (TAR) 181-250 mg/dL of 27.8% and a mean TAR > 250 mg/dL of 10.2%. The mean time below range (TBR) 54-69 mg/dL was 2%, while the mean TBR < 54 mg/dL was 0.3%. The mean glucose management indicator (GMI) was 7.3%. No significant differences were observed in FGM values for the following 90 days of follow-up. A progressive improvement in all parameters of glycaemic control was observed between the first month of FGM use and the sixth month of FGM use. Of note, there was a decrease in mean CV (40.6% to 34.1%, p = 0.25), mean TAR 181-250 (30.3% to 26%, p = 0.49), mean TAR > 250 mg/dL (16.3% to 7.7%, p = 0.09), mean TBR 54-69 mg/dL (5.2% to 2%, p = 0.16), and mean TBR < 54 mg/dL (1.8% to 0.2%, p = 0.31), along with an increase in mean values of TIR 70-180 mg/dL (46.5% to 60.5%, p = 0.09). The lack of statistical significance in the differences observed in the mean FGM values over the follow-up period may be related to the small sample size.

CONCLUSION

DM-ICI is recognised by a state of sudden-onset insulinopenia, often associated with DKA. The use of FGM systems may be a valid option for the effective management of DM-ICIs and for the prevention of severe hyperglycaemic and hypoglycaemic episodes in this condition.

Endocrine toxicities of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) are monoclonal antibodies that target two key signalling pathways related to T cell activation and exhaustion, by binding to and inhibiting cytotoxic T lymphocyte antigen 4 (CTLA4) or PD1 and its ligand PDL1. ICIs, such as nivolumab, pembrolizumab and ipilimumab, are approved for the treatment of numerous and diverse cancer types, in various combination regimens, and are now an established cornerstone of cancer therapeutics. Toxicities induced by ICIs are autoimmune in nature and are referred to as immune-related adverse events (irAEs); these events can affect any organ system in an unpredictable fashion. Importantly, irAEs can manifest as endocrinopathies involving the thyroid (hypothyroidism or thyrotoxicosis), pituitary (hypophysitis), adrenal glands (adrenal insufficiency) and pancreas (diabetes mellitus). These events are a frequent source of acute and persistent morbidity in patients treated with ICIs and can even be fatal. Over the past few years, there has been a growing understanding of the underlying pathogenesis of irAEs that has led to the development of more effective management strategies. Herein, we review the current understanding of the pathobiology, clinical manifestations and treatment approaches to endocrine toxicities arising from ICIs.

Immune Checkpoint Inhibitor-Induced Diabetes Mellitus: Potential Role of T Cells in the Underlying Mechanism

Immunotherapy is now a recognized treatment option for several types of cancer. However, some cancer patients treated with immune checkpoint inhibitors (ICIs) are subject to immune-related adverse events, including induced diabetes mellitus. The exact role and molecular/genetic action of ICIs in diabetes are still not well understood. Elucidating the underlying mechanisms in a proper fashion would allow better refining of biomarkers that would help diagnose patients at risk of altered immune system homeostasis, but would also hold the potential of new therapeutic options for diabetes. In the present narrative review, we propose to discuss the case of autoimmune diabetes following treatment with ICIs and the role of ICIs in the pathophysiology of diabetes. We also present some scarce available data on interesting potential immune therapies for diabetes.

Unravelling Checkpoint Inhibitor Associated Autoimmune Diabetes: From Bench to Bedside

Immune checkpoint inhibitors have transformed the landscape of oncological therapy, but at the price of a new array of immune related adverse events. Among these is β-cell failure, leading to checkpoint inhibitor-related autoimmune diabetes (CIADM) which entails substantial long-term morbidity. As our understanding of this novel disease grows, parallels and differences between CIADM and classic type 1 diabetes (T1D) may provide insights into the development of diabetes and identify novel potential therapeutic strategies. In this review, we outline the knowledge across the disciplines of endocrinology, oncology and immunology regarding the pathogenesis of CIADM and identify possible management strategies.

Evolving insights into the mechanisms of toxicity associated with immune checkpoint inhibitor therapy

Immune checkpoint inhibitors have emerged as a revolutionary treatment option for patients with various types of malignancy. Although these agents afford a significant improvement in outcomes for melanoma and other previously untreatable malignancies, their novel mechanism of action may predispose patients to immune-related adverse effects (irAEs). In the tumour neoantigen environment, these irAEs are due to the activation of the immune system by the blockade of suppressive checkpoints, leading to increases in T-cell activation and proliferation. IrAEs have been reported in almost any organ and at any point in time, even months to years after discontinuation of therapy. Certain populations with distinct physiological changes, genetic risk factors, and specific antigen exposures may be more highly predisposed to develop irAEs. This review discusses the incidence and mechanisms of irAEs and the relationship between host factors and irAE occurrence.

Immune-evasive human islet-like organoids ameliorate diabetes

While stem cell-derived islets hold promise as a therapy for insulin-dependent diabetes, challenges remain in achieving this goal^1–6. Here we generate human islet-like organoids (HILOs) from induced pluripotent stem cells (iPSCs) and show that non-canonical WNT4 signaling drives the metabolic maturation necessary for robust ex vivo glucose-stimulated insulin secretion. These functionally mature HILOs contain endocrine-like cell types that, upon transplantation, rapidly re-establish glucose homeostasis in diabetic NOD-SCID mice. Overexpression of the immune checkpoint protein PD-L1 protected HILO xenografts such that they were able to restore glucose homeostasis in immune-competent diabetic mice for 50 days. Furthermore, ex vivo interferon gamma stimulation induced endogenous PD-L1 expression and restricted T cell activation and graft rejection. The generation of glucose-responsive islet-like organoids able to avoid immune detection provides a promising alternative to cadaveric and device-dependent therapies in the treatment of diabetes.

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.

Role of the PD-1/PD-L1 Dyad in the Maintenance of Pancreatic Immune Tolerance for Prevention of Type 1 Diabetes

The human pancreas, like almost all organs in the human body, is immunologically tolerated despite the presence of innate and adaptive immune cells that promptly mediate protective immune responses against pathogens in situ. The PD-1/PD-L1 inhibitory pathway seems to play a key role in the maintenance of immune tolerance systemically and within the pancreatic tissue. Tissue resident memory T cells (TRM), T regulatory cells (Treg), macrophages and even β cells exhibit PD-1 or PD-L1 expression that contributes in controlling pancreatic immune homeostasis and tolerance. Dysregulation of the PD-1/PD-L1 axis as shown by animal studies and our recent experience with checkpoint inhibitory blockade in humans can lead to immune dysfunctions leading to chronic inflammatory disease and to type 1 diabetes (T1D) in genetically susceptible individuals. In this review, we discuss the role of the PD-1/PD-L1 axis in pancreatic tissue homeostasis and tolerance, speculate how genetic and environmental factors can regulate the PD-1/PD-L1 pathway, and discuss PD-1/PD-L1-based therapeutic approaches for pancreatic islet transplantation and T1D treatment.

Immunotherapy-induced endocrinopathies: assessment, management and monitoring

Immunotherapy with checkpoint inhibitors has transformed the treatment of cancer, but frequently results in immune-mediated adverse events affecting multiple organs, amongst which endocrine adverse events are frequent. The patterns of endocrine adverse events differ between inhibitors of the CTLA-4 and PD-1/PD-L1 pathways, but most frequently involve the thyroid and pituitary with insulin deficient diabetes also emerging as an important adverse event. These frequently result in long-lasting hormone deficiency requiring replacement. This review explores the mechanism of action of checkpoint inhibitors and details the expected endocrine adverse events and typical presentations. The effect of high-dose glucocorticoids therapy to treat nonendocrine adverse events is also discussed.

Programmed Death-1 Restrains the Germinal Center in Type 1 Diabetes

Programmed death-1 (PD-1) inhibits T and B cell function upon ligand binding. PD-1 blockade revolutionized cancer treatment, and although numerous patients respond, some develop autoimmune-like symptoms or overt autoimmunity characterized by autoantibody production. PD-1 inhibition accelerates autoimmunity in mice, but its role in regulating germinal centers (GC) is controversial. To address the role of PD-1 in the GC reaction in type 1 diabetes, we used tetramers to phenotype insulin-specific CD4⁺ T and B cells in NOD mice. PD-1 or PD-L1 deficiency, and PD-1 but not PD-L2 blockade, unleashed insulin-specific T follicular helper CD4⁺ T cells and enhanced their survival. This was concomitant with an increase in GC B cells and augmented insulin autoantibody production. The effect of PD-1 blockade on the GC was reduced when mice were treated with a mAb targeting the insulin peptide:MHC class II complex. This work provides an explanation for autoimmune side effects following PD-1 pathway inhibition and suggests that targeting the self-peptide:MHC class II complex might limit autoimmunity arising from checkpoint blockade.

Effect of Stem Cells and Gene Transfected Stem Cells Therapy on the Pancreas of Experimentally Induced Type 1 Diabetes

Background and Objectives

Insulin secretion entirely depends on Ca²⁺ influx and sequestration into endoplasmic reticulum (ER) of β-cells, performed by Sarco-ER Ca²⁺-ATPase 2b (SERCA2b). In diabetes, SERCA2b is decreased in the β-cells leading to impaired intracellular Ca²⁺ homeostasis and insulin secretion. Adipose mesenchymal stem cells (AMSCs) play a potential role in transplantation in animal models. The present study aimed at investigating and comparing the therapeutic effect of non-transfected AMSCs and SERCA2b gene transfected AMSCs on the pancreas of induced diabetes type 1 in rat.

Methods and Results

58 adult male albino rats were divided into: Donor group: 22 rats, 2 for isolation, propagation and characterization of AMSCs and SERCA2b transfected AMSCs, in addition 20 for isolated islet calcium level assessment. Group I (Control Group): 6 rats, Group II (Diabetic Group): 10 rats, 50 mg streptozotocin (STZ) were injected intraperitoneal (IP), Group III (AMSCs Group): 10 rats, 1×10⁶ AMSCs were injected intravenous and Group IV (SERCA2b transfected AMSCs Group): 10 rats, 1×10⁶SERCA2b transfected AMSCs were injected as in group III. Groups I, II, III and IV were sacrified 3 weeks following confirmation of diabetes. Serological, histological, morphometric studies and quantitative polymerase chain reaction (qPCR) were performed. Nuclear, cytoplasmic degenerative and extensive fibrotic changes were detected in the islets of group II that regressed in groups III and IV. Isolated islet calcium, blood glucose, plasma insulin and qPCR were confirmative.

Conclusions

AMSCs and SERCA2b gene transfected AMSCs therapy proved definite therapeutic effect, more obvious in response to SERCA2b gene transfected AMSCs.

Interferon-gamma drives programmed death-ligand 1 expression on islet β cells to limit T cell function during autoimmune diabetes

Type 1 diabetes is caused by autoreactive T cell-mediated β cell destruction. Even though co-inhibitory receptor programmed death-1 (PD-1) restrains autoimmunity, the expression and regulation of its cognate ligands on β cell remains unknown. Here, we interrogated β cell-intrinsic programmed death ligand-1 (PD-L1) expression in mouse and human islets. We measured a significant increase in the level of PD-L1 surface expression and the frequency of PD-L1+ β cells as non-obese diabetic (NOD) mice aged and developed diabetes. Increased β cell PD-L1 expression was dependent on T cell infiltration, as β cells from Rag1-deficient mice lacked PD-L1. Using Rag1-deficient NOD mouse islets, we determined that IFN-γ promotes β cell PD-L1 expression. We performed analogous experiments using human samples, and found a significant increase in β cell PD-L1 expression in type 1 diabetic samples compared to type 2 diabetic, autoantibody positive, and non-diabetic samples. Among type 1 diabetic samples, β cell PD-L1 expression correlated with insulitis. In vitro experiments with human islets from non-diabetic individuals showed that IFN-γ promoted β cell PD-L1 expression. These results suggest that insulin-producing β cells respond to pancreatic inflammation and IFN-γ production by upregulating PD-L1 expression to limit self-reactive T cells.

Cutting Edge: Dual TCRα Expression Poses an Autoimmune Hazard by Limiting Regulatory T Cell Generation

Despite accounting for 10-30% of the T cell population in mice and humans, the role of dual TCR-expressing T cells in immunity remains poorly understood. It has been hypothesized that dual TCR T cells pose an autoimmune hazard by allowing self-reactive TCRs to escape thymic selection. We revisited this hypothesis using the NOD murine model of type 1 diabetes. We bred NOD mice hemizygous at both TCRα and β (TCRα^+/- β^+/-) loci, rendering them incapable of producing dual TCR T cells. We found that the lack of dual TCRα expression skewed the insulin-specific thymocyte population toward greater regulatory T (T_reg) cell commitment, resulting in a more tolerogenic T_reg to conventional T cell ratio and protection from diabetes. These data support a novel hypothesis by which dual TCR expression can promote autoimmunity by limiting agonist selection of self-reactive thymocytes into the T_reg cell lineage.