Understanding adverse events of immunotherapy: A mechanistic perspective

Restricting datasets to classifiable samples augments discovery of immune disease biomarkers

Immunological diseases are typically heterogeneous in clinical presentation, severity and response to therapy. Biomarkers of immune diseases often reflect this variability, especially compared to their regulated behaviour in health. This leads to a common difficulty that frustrates biomarker discovery and interpretation - namely, unequal dispersion of immune disease biomarker expression between patient classes necessarily limits a biomarker's informative range. To solve this problem, we introduce dataset restriction, a procedure that splits datasets into classifiable and unclassifiable samples. Applied to synthetic flow cytometry data, restriction identifies biomarkers that are otherwise disregarded. In advanced melanoma, restriction finds biomarkers of immune-related adverse event risk after immunotherapy and enables us to build multivariate models that accurately predict immunotherapy-related hepatitis. Hence, dataset restriction augments discovery of immune disease biomarkers, increases predictive certainty for classifiable samples and improves multivariate models incorporating biomarkers with a limited informative range. This principle can be directly extended to any classification task.

Lung injury induces a polarized immune response by self-antigen-specific CD4+ Foxp3+ regulatory T cells

Self-antigen-specific T cells are prevalent in the mature adaptive immune system but are regulated through multiple mechanisms of tolerance. However, inflammatory conditions such as tissue injury may allow these T cells to break tolerance and trigger autoimmunity. To understand how the T cell repertoire responds to the presentation of self-antigen under highly stimulatory conditions, we use peptide:major histocompatibility complex (MHC) class II tetramers to track the behavior of endogenous CD4+ T cells with specificity to a lung-expressed self-antigen in mouse models of immune-mediated lung injury. Acute injury results in the exclusive expansion of CD4+ regulatory T cells (Tregs) that is dependent on self-antigen recognition and interleukin-2 (IL-2). Conversely, conventional CD4+ T cells of the same self-antigen specificity remain unresponsive even following Treg ablation. Thus, the self-antigen-specific CD4+ T cell repertoire is poised to serve a regulatory function during acute tissue damage to limit further damage and the possibility of autoimmunity.

Spatiotemporal regulation of peripheral T cell tolerance

The incomplete removal of T cells that are reactive against self-proteins during their differentiation in the thymus requires mechanisms of tolerance that prevent their effector function within the periphery. A further challenge is imposed by the need to establish tolerance to the holobiont self, which comprises a highly complex community of commensal microorganisms. Here, we review recent advances in the investigation of peripheral T cell tolerance, focusing on new insights into mechanisms of tolerance to the gut microbiota, including tolerogenic antigen-presenting cell types and immunomodulatory lymphocytes, and their layered ontogeny that underlies developmental windows for establishing intestinal tolerance. While emphasizing the intestine as a model tissue for studying peripheral T cell tolerance, we highlight overlapping and distinct pathways that underlie tolerance to self-antigens versus commensal antigens within a broader framework for immune tolerance.

Lung injury induces a polarized immune response by self antigen-specific Foxp3 + regulatory T cells

Self antigen-specific T cells are prevalent in the mature adaptive immune system, but are regulated through multiple mechanisms of tolerance. However, inflammatory conditions such as tissue injury may provide these T cells with an opportunity to break tolerance and trigger autoimmunity. To understand how the T cell repertoire responds to the presentation of self antigen under highly stimulatory conditions, we used peptide:MHCII tetramers to track the behavior of endogenous CD4 + T cells with specificity to a lung-expressed self antigen in mouse models of immune-mediated lung injury. Acute injury resulted in the exclusive expansion of regulatory T cells (Tregs) that was dependent on self antigen recognition and IL-2. Conversely, conventional T cells of the same self antigen specificity remained unresponsive, even following Treg ablation. Thus, the self antigen-specific T cell repertoire is poised to serve a regulatory function during acute tissue damage to limit further damage and the possibility of autoimmunity.

Cutaneous immune-related adverse events are associated with longer overall survival in advanced cancer patients on immune checkpoint inhibitors: A multi-institutional cohort study

BACKGROUND

Cutaneous immune-related adverse events (cirAEs) occur in up to 40% of immune checkpoint inhibitor (ICI) recipients. However, the association of cirAEs with survival remains unclear.

OBJECTIVE

To investigate the association of cirAEs with survival among ICI recipients.

METHODS

ICI recipients were identified from the Mass General Brigham healthcare system and Dana-Farber Cancer Institute. Patient charts were reviewed for cirAE development within 2 years after ICI initiation. Multivariate time-varying Cox proportional hazards models, adjusted for age, sex, race/ethnicity, Charlson Comorbidity Index, ICI type, cancer type, and year of ICI initiation were utilized to investigate the impact of cirAE development on overall survival.

RESULTS

Of the 3731 ICI recipients, 18.1% developed a cirAE. Six-month landmark analysis and time-varying Cox proportional hazards models demonstrated that patients who developed cirAEs were associated with decreased mortality (hazardratio [HR] = 0.87, P = .027), particularly in patients with melanoma (HR = 0.67, P = .003). Among individual morphologies, lichenoid eruption (HR = 0.51, P < .001), psoriasiform eruption (HR = 0.52, P = .005), vitiligo (HR = 0.29, P = .007), isolated pruritus without visible manifestation of rash (HR = 0.71, P = .007), acneiform eruption (HR = 0.34, P = .025), and non-specific rash (HR = 0.68, P < .001) were significantly associated with better survival after multiple comparisons adjustment.

LIMITATIONS

Retrospective design; single geography.

CONCLUSION

CirAE development is associated with improved survival among ICI recipients, especially patients with melanoma.

Immune checkpoint receptors in autoimmunity

Immune checkpoint receptors such as programmed cell death protein 1 (PD-1), cytotoxic T-lymphocyte associated protein 4 (CTLA-4), lymphocyte-activation gene 3 (LAG-3), and T cell immunoglobulin and ITIM domain (TIGIT) have distinct and overlapping inhibitory functions that regulate Tcell activation, differentiation, and function. These inhibitory receptors also mediate tolerance, and dysregulation of these receptors can result in a breach of tolerance and the development of autoimmune syndromes. Similarly, antibody blockade of immune checkpoint receptors or their ligands for cancer immunotherapy may trigger a spectrum of organ inflammation that resembles autoimmunity, termed immune-related adverse events (irAE). In this review, we discuss recent advances in the regulation of autoimmunity by immune checkpoint receptors. We highlight coordinated gene expression programs linking checkpoint receptors, heterogeneity within autoreactive T-cell populations, parallels between irAE and autoimmunity, and bidirectional functional interactions between immune checkpoint receptors and their ligands.

Cutaneous immune-related adverse events are associated with longer overall survival in advanced cancer patients on immune checkpoint inhibitors: a multi-institutional cohort study

Background

Cutaneous immune-related adverse events (cirAEs) occur in up to 40% of immune checkpoint inhibitor (ICI) recipients. However, the association of cirAEs with survival remains unclear.

Objective

To investigate the association of cirAEs with survival among ICI recipients.

Methods

ICI recipients were identified from the Mass General Brigham healthcare system (MGB) and Dana-Farber Cancer Institute (DFCI). Patient charts were reviewed for cirAE development within 2 years after ICI initiation. Multivariate time-varying Cox proportional hazards models, adjusted for age, sex, race/ethnicity, Charlson Comorbidity Index, ICI type, cancer type, and year of ICI initiation were utilized to investigate the impact of cirAE development on overall survival.

Results

Of the 3,731 ICI recipients, 18.1% developed a cirAE. 6-month landmark analysis and time-varying Cox proportional hazards models demonstrated that patients who developed cirAEs were associated with decreased mortality (HR=0.87,p=0.027), particularly in melanoma patients (HR=0.67,p=0.003). Among individual morphologies, lichenoid eruption (HR=0.51,p<0.001), psoriasiform eruption (HR=0.52,p=0.005), vitiligo (HR=0.29,p=0.007), isolated pruritus without visible manifestation of rash (HR=0.71,p=0.007), acneiform eruption (HR =0.34,p=0.025), and non-specific rash (HR=0.68, p<0.001) were significantly associated with better survival after multiple comparisons adjustment.

Limitations

Retrospective design; single geography.

Conclusion

CirAE development is associated with improved survival among ICI recipients, especially melanoma patients.

Capsule Summary

Patients on immune checkpoint inhibitors (ICIs) who developed cutaneous immune-related adverse events (cirAEs) had favorable outcomes. This was especially notable for melanoma patients who had cirAEs, both those with vitiligo and other morphologies.Development of cirAEs in ICI-treated patients can be used to prognosticate survival and guide treatment decisions.

Autoreactive CD8+ T cells are restrained by an exhaustion-like program that is maintained by LAG3

Impaired chronic viral and tumor clearance has been attributed to CD8⁺ T cell exhaustion, a differentiation state in which T cells have reduced and altered effector function that can be partially reversed upon blockade of inhibitory receptors. The role of the exhaustion program and transcriptional networks that control CD8⁺ T cell function and fate in autoimmunity is not clear. Here we show that intra-islet CD8⁺ T cells phenotypically, transcriptionally, epigenetically and metabolically possess features of canonically exhausted T cells, yet maintain important differences. This 'restrained' phenotype can be perturbed and disease accelerated by CD8⁺ T cell-restricted deletion of the inhibitory receptor lymphocyte activating gene 3 (LAG3). Mechanistically, LAG3-deficient CD8⁺ T cells have enhanced effector-like functions, trafficking to the islets, and have a diminished exhausted phenotype, highlighting a physiological role for an exhaustion program in limiting autoimmunity and implicating LAG3 as a target for autoimmune therapy.

Paraneoplastic Neurological Syndromes: Transitioning Between the Old and the New

PURPOSE OF REVIEW

Paraneoplastic neurological syndromes (PNS) are caused by nervous system-targeting aberrant anti-tumoral immune responses. We review the updated criteria for PNS diagnosis, incorporating novel information on clinical phenotypes, neuronal autoantibodies (Nabs), and tumors. The impact of the oncologic use of immune checkpoint inhibitors (ICI) on PNS occurrence is also addressed.

RECENT FINDINGS

Clinical phenotypes and Nabs are redefined as "high/intermediate/low" risk, following the frequency of cancer association. Nabs, the diagnostic hallmark of PNS, can target intracellular or surface neuronal proteins, with important prognostic and pathogenic implications. Many novel assays have been incorporated into laboratory diagnostics, that is becoming increasingly complex. ICI fight tumors, but favor autoimmunity, thus increasing the incidence of PNS-like disorders. Overcoming the old PNS criteria, the new ones are centered around the presence of tumor. Clinical presentation, Nabs, and tumor findings are translated in diagnostic scores, providing a useful tool for PNS diagnosis and management.

Transcriptional and post-transcriptional regulation of checkpoint genes on the tumour side of the immunological synapse

Cancer is a disease of the genome, therefore, its development has a clear Mendelian component, demonstrated by well-studied genes such as BRCA1 and BRCA2 in breast cancer risk. However, it is known that a single genetic variant is not enough for cancer to develop leading to the theory of multistage carcinogenesis. In many cases, it is a sequence of events, acquired somatic mutations, or simply polygenic components with strong epigenetic effects, such as in the case of brain tumours. The expression of many genes is the product of the complex interplay between several factors, including the organism’s genotype (in most cases Mendelian-inherited), genetic instability, epigenetic factors (non-Mendelian-inherited) as well as the immune response of the host, to name just a few. In recent years the importance of the immune system has been elevated, especially in the light of the immune checkpoint genes discovery and the subsequent development of their inhibitors. As the expression of these genes normally suppresses self-immunoreactivity, their expression by tumour cells prevents the elimination of the tumour by the immune system. These discoveries led to the rapid growth of the field of immuno-oncology that offers new possibilities of long-lasting and effective treatment options. Here we discuss the recent advances in the understanding of the key mechanisms controlling the expression of immune checkpoint genes in tumour cells.

Catch and release: freeing up PD-L1 ameliorates autoimmunity

The binding of PD-L1 to CD80 on antigen-presenting cells prevents PD-1 ligation on T cells. Therapeutic blockade of the cis-PD-L1–CD80 interaction liberates PD-L1 to bind to PD-1, inhibits autoreactive T cells and robustly alleviates autoimmune symptoms.

Nanovesicle-Mediated Targeted Delivery of Immune Checkpoint Blockades to Potentiate Therapeutic Efficacy and Prevent Side Effects

Despite the clinically proven efficacies of immune checkpoint blockades, including anti-cytotoxic T lymphocyte-associated protein 4 antibody (αCTLA-4), the low response rate and immune-related adverse events (irAEs) in cancer patients represent major drawbacks of the therapy. These drawbacks of αCTLA-4 therapy are mainly due to the suboptimal activation of tumor-specific cytotoxic T lymphocytes (CTLs) and the systemic nonspecific activation of T cells. To overcome such drawbacks, αCTLA-4 is delivered by dendritic cell-derived nanovesicles presenting tumor antigens (DCNV-TAs) that exclusively interact with tumor-specific T cells, leading to selective activation of tumor-specific CTLs. Compared to conventional αCTLA-4 therapy, treatment with αCTLA-4-conjugated DCNV-TAs significantly inhibits tumor growth and reduces irAEs in syngeneic tumor-bearing mice. This study demonstrates that the spatiotemporal presentation of both αCTLA-4 and tumor antigens enables selective activation of tumor-specific T cells and potentiates the antitumor efficacy of αCTLA-4 without inducing systemic irAEs.

Oral Immune-Related Adverse Events Caused by Immune Checkpoint Inhibitors: Salivary Gland Dysfunction and Mucosal Diseases

Conventional chemotherapy and targeted therapies have limited efficacy against advanced head and neck squamous cell carcinoma (HNSCC). The immune checkpoint inhibitors (ICIs) such as antibodies against CTLA-4, PD-1, and PD-L1 interrupt the co-inhibitory pathway of T cells and enhance the ability of CD8+ T cells to destroy tumors. Even in advanced HNSCC patients with recurrent diseases and distant metastasis, ICI therapy shows efficiency and become an effective alternative to conventional chemotherapy. However, as this therapy releases the immune tolerance state, cytotoxic CD8+ T cells can also attack organs and tissues expressing self-antigens that cross-react with tumor antigens and induce immune-related adverse events (irAEs). When patients with HNSCC are treated with ICIs, autoimmune diseases occur in multiple organs including the skin, digestive tract, endocrine system, liver, and respiratory tract. Treatment of various malignancies, including HNSCC, with ICIs may result in the appearance of oral irAEs. In the oral cavity, an oral lichenoid reaction (OLR) and pemphigoid develop. Sicca syndrome also occurs in association with ICIs, affecting the salivary glands to induce xerostomia. It is necessary to elucidate the pathogenic mechanisms of these intractable diseases that are not seen with conventional therapy. Early diagnosis and appropriate approaches to irAEs are needed for efficient treatment of advanced HNSCC by ICIs.

Cell surface sphingomyelin: key role in cancer initiation, progression, and immune evasion

Cell surface biochemical changes, notably excessive increase in outer leaflet sphingomyelin (SM) content, are important in cancer initiation, growth, and immune evasion. Innumerable reports describe methods to initiate, promote, or enhance immunotherapy of clinically detected cancer, notwithstanding the challenges, if not impossibility, of identification of tumor-specific, or associated antigens, the lack of tumor cell surface membrane expression of major histocompatibility complex (MHC) class I alpha and β2 microglobulin chains, and lack of expression or accessibility of Fas and other natural killer cell immune checkpoint molecules. Conversely, SM synthesis and hydrolysis are increasingly implicated in initiation of carcinogenesis and promotion of metastasis. Surface membrane SM readily forms inter- and intra- molecular hydrogen bond network, which excessive tightness would impair cell-cell contact inhibition, inter- and intra-cellular signals, metabolic pathways, and susceptibility to host immune cells and mediators. The present review aims at clarifying the tumor immune escape mechanisms, which face common immunotherapeutic approaches, and attracting attention to an entirely different, neglected, key aspect of tumorigenesis associated with biochemical changes in the cell surface that lead to failure of contact inhibition, an instrumental tumorigenesis mechanism. Additionally, the review aims to provide evidence for surface membrane SM levels and roles in cells resistance to death, failure to respond to growth suppressor signals, and immune escape, and to suggest possible novel approaches to cancer control and cure.

PD-1/PD-L1 blockade: Prospectives for immunotherapy in cancer and autoimmunity

Immune checkpoint blockade therapy (ICBT) has become a successful cancer treatment approach in the field of cancer immunotherapy. Blockade of programmed death 1 (PD-1) and programmed death-ligand 1 (PD-L1) with monoclonal antibodies have been known as successful examples of cancer immunotherapy in recent years. Although ICBT has been shown to be beneficial in cancers, such benefits have only been seen in a portion of cancer patients. In this regard, enhancing the therapeutic effects of inhibiting PD-1 and PD-L1 and reducing the side effects of this approach can be considered as a potential approach in a successful ICBT. In this review, we have highlighted new viewpoints regarding improving the therapeutic effect of PD-1 and PD-L1 blockades in cancer therapy. Besides, their expression levels as a biomarker with prognostic value, their role in intestinal microbiota modulation, combination therapy, and immune-related side effects (irAEs) have been discussed.

Presynaptic Paraneoplastic Disorders of the Neuromuscular Junction: An Update

The neuromuscular junction (NMJ) is the target of a variety of immune-mediated disorders, usually classified as presynaptic and postsynaptic, according to the site of the antigenic target and consequently of the neuromuscular transmission alteration. Although less common than the classical autoimmune postsynaptic myasthenia gravis, presynaptic disorders are important to recognize due to the frequent association with cancer. Lambert Eaton myasthenic syndrome is due to a presynaptic failure to release acetylcholine, caused by antibodies to the presynaptic voltage-gated calcium channels. Acquired neuromyotonia is a condition characterized by nerve hyperexcitability often due to the presence of antibodies against proteins associated with voltage-gated potassium channels. This review will focus on the recent developments in the autoimmune presynaptic disorders of the NMJ.

Host-Directed Therapies for Cutaneous Leishmaniasis

Cutaneous leishmaniasis exhibits a wide spectrum of clinical presentations from self-resolving infections to severe chronic disease. Anti-parasitic drugs are often ineffective in the most severe forms of the disease, and in some cases the magnitude of the disease can result from an uncontrolled inflammatory response rather than unrestrained parasite replication. In these patients, host-directed therapies offer a novel approach to improve clinical outcome. Importantly, there are many anti-inflammatory drugs with known safety and efficacy profiles that are currently used for other inflammatory diseases and are readily available to be used for leishmaniasis. However, since leishmaniasis consists of a wide range of clinical entities, mediated by a diverse group of leishmanial species, host-directed therapies will need to be tailored for specific types of leishmaniasis. There is now substantial evidence that host-directed therapies are likely to be beneficial beyond autoimmune diseases and cancer and thus should be an important component in the armamentarium to modulate the severity of cutaneous leishmaniasis.

Immune-Related Mutational Landscape and Gene Signatures: Prognostic Value and Therapeutic Impact for Head and Neck Cancer

Simple Summary

Immunotherapy has emerged as a standard-of-care for most human malignancies, including head and neck cancer, but only a limited number of patients exhibit a durable clinical benefit. An urgent medical need is the establishment of accurate response predictors, which is handicapped by the growing body of molecular, cellular and clinical variables that modify the complex nature of an effective anti-tumor immune response. This review summarizes more recent efforts to elucidate immune-related mutational landscapes and gene expression signatures by integrative analysis of multi-omics data, and highlights their potential therapeutic impact for head and neck cancer. A better knowledge of the underlying principles and relevant interactions could pave the way for rational therapeutic combinations to improve the efficacy of immunotherapy, in particular for those cancer patients at a higher risk for treatment failure.

Abstract

Immunotherapy by immune checkpoint inhibition has become a main pillar in the armamentarium to treat head and neck cancer and is based on the premise that the host immune system can be reactivated to successfully eliminate cancer cells. However, the response rate remains low and only a small subset of head and neck cancer patients achieves a durable clinical benefit. The availability of multi-omics data and emerging computational technologies facilitate not only a deeper understanding of the cellular composition in the tumor immune microenvironment but also enables the study of molecular principles in the complex regulation of immune surveillance versus tolerance. These knowledges will pave the way to apply immunotherapy more precisely and effectively. This review aims to provide a holistic view on how the immune landscape dictates the tumor fate and vice versa, and how integrative analysis of multi-omics data contribute to our current knowledge on the accuracy of predictive biomarkers and on a broad range of factors influencing the response to immunotherapy in head and neck cancer.