Resistance Mechanisms to Anti-PD Cancer Immunotherapy.

The transformative success of antibodies targeting the PD-1 (programmed death 1)/B7-H1 (B7 homolog 1) pathway (anti-PD therapy) has revolutionized cancer treatment. However, only a fraction of patients with solid tumors and some hematopoietic malignancies respond to anti-PD therapy, and the reason for failure in other patients is less known. By dissecting the mechanisms underlying this resistance, current studies reveal that the tumor microenvironment is a major location for resistance to occur. Furthermore, the resistance mechanisms appear to be highly heterogeneous. Here, we discuss recent human cancer data identifying mechanisms of resistance to anti-PD therapy. We review evidence for immune-based resistance mechanisms such as loss of neoantigens, defects in antigen presentation and interferon signaling, immune inhibitory molecules, and exclusion of T cells. We also review the clinical evidence for emerging mechanisms of resistance to anti-PD therapy, such as alterations in metabolism, microbiota, and epigenetics. Finally, we discuss strategies to overcome anti-PD therapy resistance and emphasize the need to develop additional immunotherapies based on the concept of normalization cancer immunotherapy.

Natural innate and adaptive immunity to cancer.

The immune system can identify and destroy nascent tumor cells in a process termed cancer immunosurveillance, which functions as an important defense against cancer. Recently, data obtained from numerous investigations in mouse models of cancer and in humans with cancer offer compelling evidence that particular innate and adaptive immune cell types, effector molecules, and pathways can sometimes collectively function as extrinsic tumor-suppressor mechanisms. However, the immune system can also promote tumor progression. Together, the dual host-protective and tumor-promoting actions of immunity are referred to as cancer immunoediting. In this review, we discuss the current experimental and human clinical data supporting a cancer immunoediting process that provide the fundamental basis for further study of immunity to cancer and for the rational design of immunotherapies against cancer.

Paradoxical eruptions to targeted therapies in dermatology: A systematic review and analysis.

BACKGROUND: Antibody-based therapies that inhibit proinflammatory cytokine signaling are commonly used in dermatology. Paradoxically, these medications may induce or exacerbate inflammatory disorders. OBJECTIVE: To summarize the spectrum of manifestations, incidence, timing, potential mechanisms of, and general management approaches to paradoxical cutaneous reactions induced by cytokine-targeted antibodies in dermatology. METHODS: We performed a systematic review and analysis of published cases of cutaneous paradoxical reactions (PRs) reported in association with tumor necrosis factor α, interleukin (IL) 12/23 (p40), IL-17A/17R, IL-23 (p19), and IL-4Rα inhibitors. RESULTS: We identified 313 articles reporting 2049 cases of PRs. Tumor necrosis factor α inhibitors resulted in 91.2% (1869/2049) of all cases, followed by IL-17/17R (3.5%), IL-4Rα (2.7%), IL-12/23 (2.4%), and IL-23 (0.01%) inhibitors. Psoriasiform and eczematous eruptions were the most commonly reported, but a wide spectrum of patterns were described. Phenotypically overlapping reaction patterns were common. Time to onset typically ranged from weeks to months but could occur more than a year later. Improvement or resolution upon discontinuation of the inciting drug was common. LIMITATIONS: This was a retrospective analysis. CONCLUSIONS: Familiarity with the clinical features of PRs from cytokine-blocking antibodies may facilitate efficient recognition and management.

In silico analysis of the immunological landscape of pituitary adenomas.

PURPOSE: Immunotherapy has gained traction in the treatment of solid tumors but the immunological landscape of pituitary adenomas is not well defined. We sought to investigate the immunological composition in pituitary adenomas using RNA deconvolution (CIBERSORTx) on an existing gene expression dataset for pituitary adenomas. METHODS: We applied an established computational approach (CIBERSORTx) on 134 pituitary adenomas from a previously published gene expression dataset to infer the proportions of 22 subsets of immune cells. We investigated associations between each immune cell type and tumor subtype. RESULTS: We found that the majority of infiltrating immune cells within pituitary adenomas were comprised of M2 macrophages followed by resting CD4+ memory T cells and mast cells. Silent pituitary tumors have higher M2 macrophage fractions when compared to other subtypes. In contrast, Cushing pituitary tumors, both overt and subclinical cases, had higher CD8+ T cells fractions than GH tumors, prolactinomas, hyperthyroid tumors, and silent tumors. CONCLUSIONS: RNA deconvolution of the immune infiltrates of pituitary adenomas using CIBERSORTx suggests that most pituitary adenomas comprise of M2 macrophages, but each adenoma subtype has a unique immune landscape. This may have implications in targeting each adenoma subtype with different immunotherapies.

Checkpoint blockade cancer immunotherapy targets tumour-specific mutant antigens.

The immune system influences the fate of developing cancers by not only functioning as a tumour promoter that facilitates cellular transformation, promotes tumour growth and sculpts tumour cell immunogenicity, but also as an extrinsic tumour suppressor that either destroys developing tumours or restrains their expansion. Yet, clinically apparent cancers still arise in immunocompetent individuals in part as a consequence of cancer-induced immunosuppression. In many individuals, immunosuppression is mediated by cytotoxic T-lymphocyte associated antigen-4 (CTLA-4) and programmed death-1 (PD-1), two immunomodulatory receptors expressed on T cells. Monoclonal-antibody-based therapies targeting CTLA-4 and/or PD-1 (checkpoint blockade) have yielded significant clinical benefits-including durable responses--to patients with different malignancies. However, little is known about the identity of the tumour antigens that function as the targets of T cells activated by checkpoint blockade immunotherapy and whether these antigens can be used to generate vaccines that are highly tumour-specific. Here we use genomics and bioinformatics approaches to identify tumour-specific mutant proteins as a major class of T-cell rejection antigens following anti-PD-1 and/or anti-CTLA-4 therapy of mice bearing progressively growing sarcomas, and we show that therapeutic synthetic long-peptide vaccines incorporating these mutant epitopes induce tumour rejection comparably to checkpoint blockade immunotherapy. Although mutant tumour-antigen-specific T cells are present in progressively growing tumours, they are reactivated following treatment with anti-PD-1 and/or anti-CTLA-4 and display some overlapping but mostly treatment-specific transcriptional profiles, rendering them capable of mediating tumour rejection. These results reveal that tumour-specific mutant antigens are not only important targets of checkpoint blockade therapy, but they can also be used to develop personalized cancer-specific vaccines and to probe the mechanistic underpinnings of different checkpoint blockade treatments.

Getting Under the Skin: Targeting Cutaneous Autoimmune Disease.

Autoimmune diseases of the skin occur when the immune system attacks normal skin. The immune system can be broadly divided into an effector arm responsible for fighting infections and cancer and a regulatory arm that reduces autoreactivity and maintains immune homeostasis. Cutaneous autoimmunity develops when the equilibrium between the effector arm and regulatory arm of the immune system is disrupted. Recent insights into the inflammatory pathways that are overactive in some cutaneous autoimmune diseases have led to therapies targeting the effector arm of the immune system with greater treatment efficacy than previously used broad immunosuppressants. The current paradigm of inhibiting excessive immune activation for treating cutaneous autoimmunity will be discussed including cytokine blockade, cellular depletion, intracellular signaling blockade and costimulatory blockade. Despite the success of this approach many cutaneous autoimmune diseases lack a clearly delineated pathway to target and therefore new strategies are needed. An emerging therapeutic strategy targeting the regulatory arm of the immune system to induce tolerance and disease remission provides new hope for treating cutaneous autoimmunity. Such an approach includes cellular therapy with regulatory T cells and chimeric autoantibody receptor T cells, cytokine therapy with low-dose interleukin-2, immune checkpoint stimulation, tolerogenic vaccines and microbiome biotherapy. This mini-review will discuss the current and emerging therapeutic strategies for cutaneous autoimmune diseases and provide an organizational framework for understanding distinct mechanisms of action.

Cutaneous Lupus Erythematosus: Current and Future Pathogenesis-Directed Therapies.

Cutaneous lupus erythematosus (CLE) is an autoimmune disease of the skin with significant morbidity. Current treatments are often inadequate to control disease and there are no Food and Drug Administration (FDA)-approved therapies for this potentially debilitating disease, underscoring an unmet medical need. Recent insights into disease pathogenesis have implicated innate and adaptive immune components, including type I and type III interferons in the development of CLE. Promising clinical trials based on these insights are now underway. However, the full spectrum of immune cells, cytokines, and environmental triggers contributing to disease remain to be elucidated. In this review, we will highlight the current understanding of CLE immunopathogenesis, the ongoing clinical trial landscape, and provide a framework for designing future therapeutic strategies for CLE based on new insights into disease pathogenesis.

Cancer exome analysis reveals a T-cell-dependent mechanism of cancer immunoediting.

Cancer immunoediting, the process by which the immune system controls tumour outgrowth and shapes tumour immunogenicity, is comprised of three phases: elimination, equilibrium and escape. Although many immune components that participate in this process are known, its underlying mechanisms remain poorly defined. A central tenet of cancer immunoediting is that T-cell recognition of tumour antigens drives the immunological destruction or sculpting of a developing cancer. However, our current understanding of tumour antigens comes largely from analyses of cancers that develop in immunocompetent hosts and thus may have already been edited. Little is known about the antigens expressed in nascent tumour cells, whether they are sufficient to induce protective antitumour immune responses or whether their expression is modulated by the immune system. Here, using massively parallel sequencing, we characterize expressed mutations in highly immunogenic methylcholanthrene-induced sarcomas derived from immunodeficient Rag2(-/-) mice that phenotypically resemble nascent primary tumour cells. Using class I prediction algorithms, we identify mutant spectrin-ß2 as a potential rejection antigen of the d42m1 sarcoma and validate this prediction by conventional antigen expression cloning and detection. We also demonstrate that cancer immunoediting of d42m1 occurs via a T-cell-dependent immunoselection process that promotes outgrowth of pre-existing tumour cell clones lacking highly antigenic mutant spectrin-ß2 and other potential strong antigens. These results demonstrate that the strong immunogenicity of an unedited tumour can be ascribed to expression of highly antigenic mutant proteins and show that outgrowth of tumour cells that lack these strong antigens via a T-cell-dependent immunoselection process represents one mechanism of cancer immunoediting.

Recurrent Coxsackievirus Infection in a Patient with Lamellar Ichthyosis.

We describe a case of coxsackievirus (CV) A6 infection in a patient with lamellar ichthyosis followed by subsequent CV A8 infection within the same year. Atypical cutaneous features characterized the infection. This observation, combined with the rapidity with which reinfection occurred, suggests that the natural history of CV infection may be altered in patients with underlying ichthyoses.

Immune Inhibitory Molecule PD-1 Homolog (VISTA) Colocalizes with CD11b Myeloid Cells in Melanoma and Is Associated with Poor Outcomes.

Tumors evade immunity through the overexpression of immune inhibitory molecules in the tumor microenvironment such as PD-L1/B7-H1. An immune inhibitory molecule named PD-1 homolog (also known as V-domain Ig-containing suppressor of T cell activation [VISTA]) functions to control both T cells and myeloid cells. Current clinical trials using anti-VISTA-blocking agents for treatment of cancer are ongoing. We sought to determine the extent of VISTA expression in primary cutaneous melanomas (n = 190), identify the critical cell types expressing VISTA, and correlate its expression with PD-L1 expression using multiplexed quantitative immunofluorescence. Within the tumor subcompartments, VISTA is most highly expressed on CD11b myeloid cells, and PD-L1 is most highly expressed on CD68 myeloid cells in our melanoma cohort. There is little correlation between VISTA and PD-L1 expression intensity, suggesting that individual tumors have distinct immunosuppressive tumor microenvironments. High levels of VISTA expression on CD11b myeloid cells but not PD-L1 expression were associated with greater melanoma recurrence and greater all-cause mortality. Our findings suggest that cell-specific VISTA expression may be a negative prognostic biomarker for melanoma and a future potential therapeutic target.

Spatial characterization of interface dermatitis in cutaneous lupus reveals novel chemokine ligand-receptor pairs that drive disease.

Chemokines play critical roles in the recruitment and activation of immune cells in both homeostatic and pathologic conditions. Here, we examined chemokine ligand-receptor pairs to better understand the immunopathogenesis of cutaneous lupus erythematosus (CLE), a complex autoimmune connective tissue disorder. We used suction blister biopsies to measure cellular infiltrates with spectral flow cytometry in the interface dermatitis reaction, as well as 184 protein analytes in interstitial skin fluid using Olink targeted proteomics. Flow and Olink data concordantly demonstrated significant increases in T cells and antigen presenting cells (APCs). We also performed spatial transcriptomics and spatial proteomics of punch biopsies using digital spatial profiling (DSP) technology on CLE skin and healthy margin controls to examine discreet locations within the tissue. Spatial and Olink data confirmed elevation of interferon (IFN) and IFN-inducible CXCR3 chemokine ligands. Comparing involved versus uninvolved keratinocytes in CLE samples revealed upregulation of essential inflammatory response genes in areas near interface dermatitis, including AIM2. Our Olink data confirmed upregulation of Caspase 8, IL-18 which is the final product of AIM2 activation, and induced chemokines including CCL8 and CXCL6 in CLE lesional samples. Chemotaxis assays using PBMCs from healthy and CLE donors revealed that T cells are equally poised to respond to CXCR3 ligands, whereas CD14+CD16+ APC populations are more sensitive to CXCL6 via CXCR1 and CD14+ are more sensitive to CCL8 via CCR2. Taken together, our data map a pathway from keratinocyte injury to lymphocyte recruitment in CLE via AIM2-Casp8-IL-18-CXCL6/CXCR1 and CCL8/CCR2, and IFNG/IFNL1-CXCL9/CXCL11-CXCR3.

Crusted Scabies Presenting as Erythroderma in a Patient With Iatrogenic Immunosuppression for Treatment of Granulomatosis With Polyangiitis.

The diagnosis of scabies can be difficult when the infection presents as erythroderma. Crusted scabies is a severe form of scabies caused by cutaneous ectoparasitic infection by the mite Sarcoptes scabiei var hominis. Crusted scabies most commonly occurs in patients with underlying immunosuppression from acquired infection or subsequent to solid organ or bone marrow transplantation. We present a rare case of a patient with granulomatosis with polyangiitis (GPA) who developed azathioprine-induced myelosuppression and subsequent erythrodermic crusted scabies. It is critical to maintain a broad differential when patients present with erythroderma, especially in the setting of medication-induced immunosuppression for the treatment of autoimmune disease.

HIF-1 regulates pathogenic cytotoxic T cells in lupus skin disease.

Cutaneous lupus erythematosus (CLE) is a disfiguring autoimmune skin disease characterized by an inflammatory infiltrate rich in T cells, which are strongly implicated in tissue damage. How these cells adapt to the skin environment and promote tissue inflammation and damage is not known. In lupus nephritis, we previously identified an inflammatory gene program in kidney-infiltrating T cells that is dependent on HIF-1, a transcription factor critical for the cellular and developmental response to hypoxia as well as inflammation-associated signals. In our present studies using a mouse model of lupus skin disease, we find that skin-infiltrating CD4+ and CD8+ T cells also express high levels of HIF-1. Skin-infiltrating T cells demonstrated a strong cytotoxic signature at the transcript and protein levels, and HIF-1 inhibition abrogated skin and systemic diseases in association with decreased T cell cytotoxic activity. We also demonstrate in human CLE tissue that the T cell-rich inflammatory infiltrate exhibited increased amounts of HIF-1 and a cytotoxic signature. Granzyme B-expressing T cells were concentrated at sites of skin tissue damage in CLE, suggesting relevance of this pathway to human disease.

Clinical and research updates on the VISTA immune checkpoint: immuno-oncology themes and highlights.

Immune checkpoints limit the activation of the immune system and serve an important homeostatic function but can also restrict immune responses against tumors. Inhibition of specific immune checkpoint proteins such as the B7:CD28 family members programmed cell death protein-1 (PD-1) and cytotoxic T-lymphocyte antigen-4 (CTLA-4) has transformed the treatment of various cancers by promoting the anti-tumor activation of immune cells. In contrast to these effects, the V-domain immunoglobulin suppressor of T-cell activation (VISTA) regulates the steady state of the resting immune system and promotes homeostasis by mechanisms distinct from PD-1 and CTLA-4. The effects of VISTA blockade have been shown to include a decrease in myeloid suppression coupled with proinflammatory changes by mechanisms that are separate and distinct from other immune checkpoint proteins; in some preclinical studies these immune effects appear synergistic. Given the potential benefits of VISTA blockade in the context of cancer therapy, the second Annual VISTA Symposium was convened virtually on September 23, 2022, to review new research from investigators and immuno-oncology experts. Discussions in the meeting extended the knowledge of VISTA biology and the effects of VISTA inhibition, particularly on cells of the myeloid lineage and resting T cells, as three candidate anti-VISTA antibodies are in, or nearing, clinical development.

Cancer Immunoediting in the Era of Immuno-oncology.

Basic science breakthroughs in T-cell biology and immune-tumor cell interactions ushered in a new era of cancer immunotherapy. Twenty years ago, cancer immunoediting was proposed as a framework to understand the dynamic process by which the immune system can both control and shape cancer and in its most complex form occurs through three phases termed elimination, equilibrium, and escape. During cancer progression through these phases, tumors undergo immunoediting, rendering them less immunogenic and more capable of establishing an immunosuppressive microenvironment. Therefore, cancer immunoediting integrates the complex immune-tumor cell interactions occurring in the tumor microenvironment and sculpts immunogenicity beyond shaping antigenicity. However, with the success of cancer immunotherapy resulting in durable clinical responses in the last decade and subsequent emergence of immuno-oncology as a clinical subspecialty, the phrase "cancer immunoediting" has recently, at times, been inappropriately restricted to describing neoantigen loss by immunoselection. This focus has obscured other mechanisms by which cancer immunoediting modifies tumor immunogenicity. Although establishment of the concept of cancer immunoediting and definitive experimental evidence supporting its existence was initially obtained from preclinical models in the absence of immunotherapy, cancer immunoediting is a continual process that also occurs during immunotherapy in human patients with cancer. Herein, we discuss the known mechanisms of cancer immunoediting obtained from preclinical and clinical data with an emphasis on how a greater understanding of cancer immunoediting may provide insights into immunotherapy resistance and how this resistance can be overcome.