The causal relationship between immune cells mediating FIT3L, CCL4, OSM, and skin-derived deteriorated tumors.

OBJECTIVE: Observational studies have identified a dual effect of circulating inflammatory proteins and immune cells on cancer progression. However, the specific mechanisms of action have not been clarified in the exacerbation of cutaneous-origin tumors. Therefore, this study aims to investigate whether the causal relationship between circulating inflammatory factors and basal cell carcinoma (BCC), cutaneous malignant melanoma (SKCM), and cutaneous squamous cell carcinoma (cSCC) is regulated by immune cells. METHODS: This study employed the Two-Sample Mendelian Randomization (TSMR) approach to investigate the causal relationships between 91 circulating inflammatory factors and three prevalent types of skin cancer from a genetic perspective. Bayesian Weighted Mendelian Randomization (BWMR) was also used to validate correlation and reverse MR to assess inverse relationships. Subsequent sensitivity analyses were conducted to limit the impact of heterogeneity and pleiotropy. Finally, the two-step Mendelian Randomization (two-step MR) method was utilized to ascertain the mediating effects of specific immune cell traits in the causal pathways linking circulating inflammatory factors with BCC, SKCM, and cSCC. RESULTS: The Inverse Variance Weighted (IVW) method and the Bayesian Weighted Algorithm collectively identified nine inflammatory factors causally associated with BCC, SKCM, and cSCC. The results from Cochran's Q test, mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO), and MR-Egger intercept were not statistically significant (p < 0.05). Additionally, the proportions mediated by CD4+ CD8dim T cell %leukocyte, CD4-CD8-Natural Killer T %T cell, and CD20 on IgD-CD38-B cell for FIt3L, CCL4, and OSM were 9.26%, 8.96%, and 10.16%, respectively. CONCLUSION: Immune cell levels potentially play a role in the modulation process between circulating inflammatory proteins and cutaneous-origin exacerbated tumors. This finding offers a new perspective for the in-depth exploration of cutaneous malignancies.

Causal association between skin cancer and immune cells: mendelian randomization (MR) study.

BACKGROUND: Numerous meta-analyses and clinical studies have shown that subtypes of immune cells are associated with the development of skin cancer, but it is not clear whether this association is causal or biased. Mendelian randomization (MR) analysis reduces the effect of confounding factors and improves the accuracy of the results when compared to traditional studies. Thus, in order to examine the causal relationship between various immune cell and skin cancer, this study employs two-sample MR. METHODS: This study assesses the causal association between 731 immune cell characteristics and skin cancer using a two-sample Mendel randomization (MR) methodology. Multiple MR methods were used to bias and to derive reliable estimates of causality between instrumental variables and outcomes. Comprehensive sensitivity analyses were used to validate the stability, heterogeneity and horizontal multiplicity of the results. RESULTS: We discovered that potential causal relationships between different types of immune cells and skin cancer disease. Specifically, one type of immune cell as potentially causal to malignant melanoma of skin (MM), eight different types of immune cells as potentially causal to basal cell carcinoma (BCC), four different types of immune cells as potentially causal to actinic keratosis (AK), and no different types of immune cells were found to have a potential causal association with squamous cell carcinoma(SCC), with stability in all of the results. CONCLUSION: This study demonstrates the close connection between immune cells and skin cancer disease by genetic means, which enriches the current knowledge about the role of immune cells in skin cancer and also contributes to the design of therapeutic strategies from an immunological perspective.

Tumor-Infiltrating T Cells in Skin Basal Cell Carcinomas and Squamous Cell Carcinomas: Global Th1 Preponderance with Th17 Enrichment-A Cross-Sectional Study.

Basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) are high-incidence, non-melanoma skin cancers (NMSCs). The success of immune-targeted therapies in advanced NMSCs led us to anticipate that NMSCs harbored significant populations of tumor-infiltrating lymphocytes with potential anti-tumor activity. The main aim of this study was to characterize T cells infiltrating NMSCs. Flow cytometry and immunohistochemistry were used to assess, respectively, the proportions and densities of T cell subpopulations in BCCs (n = 118), SCCs (n = 33), and normal skin (NS, n = 30). CD8+ T cells, CD4+ T cell subsets, namely, Th1, Th2, Th17, Th9, and regulatory T cells (Tregs), CD8+ and CD4+ memory T cells, and γδ T cells were compared between NMSCs and NS samples. Remarkably, both BCCs and SCCs featured a significantly higher Th1/Th2 ratio (~four-fold) and an enrichment for Th17 cells. NMSCs also showed a significant enrichment for IFN-γ-producing CD8+T cells, and a depletion of γδ T cells. Using immunohistochemistry, NMSCs featured denser T cell infiltrates (CD4+, CD8+, and Tregs) than NS. Overall, these data favor a Th1-predominant response in BCCs and SCCs, providing support for immune-based treatments in NMSCs. Th17-mediated inflammation may play a role in the progression of NMSCs and thus become a potential therapeutic target in NMSCs.

BerEP4-Negative Basal Cell Carcinoma: An Immunophenotype Not to Forget.

ABSTRACT: Basal cell carcinoma (BCC) is the most common cancer worldwide. Although not typically metastatic, BCC can be locally destructive. BerEP4 is an antibody against CD326, an epithelial cell adhesion molecule (EpCAM) that is expressed on epithelial progenitor cells and carcinomas. BerEP4 has been reported to have a 100% positive sensitivity in basal cell carcinomas, but a much lower sensitivity for a variety of other carcinomas, including clear cell renal cell carcinoma and metastatic renal cell carcinoma. A 74-year-old woman presented with a BerEP4-negative, but anti-renal cell antibody-positive BCC, and the stark clinical implications of misdiagnosis. This case stresses the importance of considering BerEP4-negative BCC, even when other abnormal features are present.

HLA-G, cytokines, and cytokine receptors in the non-aggressive basal cell carcinoma microenvironment.

Non-aggressive basal cell carcinoma (BCC) growth is slow and might be mediated by the immune system. This study analysed the human leukocyte antigen (HLA)-G expression and cytokine profile in non-aggressive BCC subtypes from distinct locations. HLA-G was evaluated via immunohistochemistry and cytokine expression was analysed by a quantitative real-time polymerase chain reaction in 26 primary BCC samples, including nodular BCC (nBCC, n = 16) and superficial BCC (n = 10) from cephalic (ceBCC, n = 12) and non-cephalic (n = 14) locations, and by bioinformatics analysis of public GEO databases. Inflammatory infiltrate was concentrated around the tumour nests. HLA-G-positive inflammatory cells (53.85%) were more abundant than HLA-G-positive tumour cells (21.54%, p < 0.001). HLA-G immunoreactivity was predominantly cytoplasmic in BCC cells and was primarily associated with lymphocytes and macrophages surrounding the tumour. nBCC showed a higher percentage of HLA-G-positive tumour cells (p = 0.04), and ceBCC showed stronger intensity (p = 0.04). IFN-gamma and IL-10 expression were 1.95 and 1.22-fold higher, respectively, relative to that in normal skin, with a positive correlation between them (r = 0.61; p = 0.002). IL-23 expression was higher in nBCC (p = 0.04) and positively correlated (r = 0.47; p = 0.05) with slight intensity of HLA-G-positive tumour cells. The up-regulation of IL23A and IL10RB and down-regulation of IFNGR1 and IL4R gene expression in BCC compared to levels in adjacent tissues were demonstrated in the GSE125285 dataset. The exhibited cytokine profile was consistent with the induction of HLA-G expression in non-aggressive BCC subtypes. HLA-G expression in tumour cells and inflammatory cells surrounding BCCs supports the generation of inhibitory signals on various immune cells that exert anti-tumour responses.

Expression of p53 up-regulated modulator of apoptosis (PUMA) in non-melanoma skin cancer of long-term immunosuppressed solid organ transplant recipients compared to immunocompetent patients.

The risk of UV radiation (UVR)-induced non-melanoma skin cancer (NMSC) is dramatically increased in immunosuppressed organ transplant recipients compared to immunocompetent patients. In the skin, p53 up-regulated modulator of apoptosis (PUMA) is a central regulator of apoptosis in response to UVR damage and immune response regulation. Data on the expression of PUMA in patients with NMSC relative to immune status is limited To study differences in the expression and distribution of PUMA in cutaneous SCC and BCC by immunohistochemistry between immunocompetent patients and organ transplant recipients, and the effect of CsA-containing immunosuppressive maintenance regimens on this expression. PUMA expression in SCC (n = 34) and BCC (n = 20) was analysed comparatively by immunohistochemical staining in matched cohorts of 27 immunocompetent patients and 27 organ transplant recipients SCC and BCC showed unequivocal positive PUMA expression, however, there was no significant difference in NMSC between organ transplant recipients and immunocompetent patients. A 17% reduction in staining score for PUMA in SCC, but not in BCC, of organ transplant recipients treated with a cyclosporin (CsA)-containing regimen was noted compared to organ transplant recipients without chronic CsA intake (p = 0.0381) PUMA expression in SCC, but not BCC, is significantly reduced by CsA-containing therapy, suggesting a disturbance of apoptosis by iatrogenic immunosuppression with a divergent impact on SCC and BCC.

Immune checkpoint inhibitors for advanced or metastatic basal cell carcinoma: how much evidence do we need?

Basal cell carcinoma (BCC) is one of the most frequent and most curable tumors at its early stages. BCC rarely metastasizes and its treatment in this setting is still challenging. Hedgehog inhibitors showed an activity in advanced or metastatic disease. However, there is an unmet need for new agents. Immune checkpoint inhibitors have been assessed in melanoma and other cutaneous tumors, and very recently an anti-PD1 was approved for advanced BCC. In this paper, available data are reviewed on experimental and preclinical studies evaluating immunotherapy in BCC, as well as on the clinical evidence supporting the efficacy and safety of immune checkpoint inhibitors for advanced or metastatic BCC based on case reports, case series and clinical trials.

Genetic and functional interaction network analysis reveals global enrichment of regulatory T cell genes influencing basal cell carcinoma susceptibility.

BACKGROUND: Basal cell carcinoma (BCC) of the skin is the most common form of human cancer, with more than 90% of tumours presenting with clear genetic activation of the Hedgehog pathway. However, polygenic risk factors affecting mechanisms such as DNA repair and cell cycle checkpoints or which modulate the tumour microenvironment or host immune system play significant roles in determining whether genetic mutations culminate in BCC development. We set out to define background genetic factors that play a role in influencing BCC susceptibility via promoting or suppressing the effects of oncogenic drivers of BCC. METHODS: We performed genome-wide association studies (GWAS) on 17,416 cases and 375,455 controls. We subsequently performed statistical analysis by integrating data from population-based genetic studies of multi-omics data, including blood- and skin-specific expression quantitative trait loci and methylation quantitative trait loci, thereby defining a list of functionally relevant candidate BCC susceptibility genes from our GWAS loci. We also constructed a local GWAS functional interaction network (consisting of GWAS nearest genes) and another functional interaction network, consisting specifically of candidate BCC susceptibility genes. RESULTS: A total of 71 GWAS loci and 46 functional candidate BCC susceptibility genes were identified. Increased risk of BCC was associated with the decreased expression of 26 susceptibility genes and increased expression of 20 susceptibility genes. Pathway analysis of the functional candidate gene regulatory network revealed strong enrichment for cell cycle, cell death, and immune regulation processes, with a global enrichment of genes and proteins linked to TReg cell biology. CONCLUSIONS: Our genome-wide association analyses and functional interaction network analysis reveal an enrichment of risk variants that function in an immunosuppressive regulatory network, likely hindering cancer immune surveillance and effective antitumour immunity.

Epidermal activation of Hedgehog signaling establishes an immunosuppressive microenvironment in basal cell carcinoma by modulating skin immunity.

Genetic activation of hedgehog/glioma-associated oncogene homolog (HH/GLI) signaling causes basal cell carcinoma (BCC), a very frequent nonmelanoma skin cancer. Small molecule targeting of the essential HH effector Smoothened (SMO) has proven an effective therapy of BCC, though the frequent development of drug resistance poses major challenges to anti-HH treatments. In light of recent breakthroughs in cancer immunotherapy, we analyzed the possible immunosuppressive mechanisms in HH/GLI-induced BCC in detail. Using a genetic mouse model of BCC, we identified profound differences in the infiltration of BCC lesions with cells of the adaptive and innate immune system. Epidermal activation of Hh/Gli signaling led to an accumulation of immunosuppressive regulatory T cells, and to an increased expression of immune checkpoint molecules including programmed death (PD)-1/PD-ligand 1. Anti-PD-1 monotherapy, however, did not reduce tumor growth, presumably due to the lack of immunogenic mutations in common BCC mouse models, as shown by whole-exome sequencing. BCC lesions also displayed a marked infiltration with neutrophils, the depletion of which unexpectedly promoted BCC growth. The study provides a comprehensive survey of and novel insights into the immune status of murine BCC and serves as a basis for the design of efficacious rational combination treatments. This study also underlines the need for predictive immunogenic mouse models of BCC to evaluate the efficacy of immunotherapeutic strategies in vivo.

Risk of Non-Melanoma Skin Cancer in Connective Tissue Disease and The Impact of Immunosuppressive Therapy.

The risk of skin cancer in connective tissue disease and the impact of immunosuppressive therapy on this risk has not been well studied. The objective of this study is to investigate the risk of non-melanoma skin cancer in patients with connective tissue disease and to assess the impact of immunosuppressive therapy on this risk. This is a retrospective case control cohort study of 8281 patients with connective tissue disease (systemic lupus erythematosus, Sjogren’s disease and scleroderma) and 8281 age, race, and gender matched controls followed for a 5-year period between 2002-2012, who obtained their care from a large integrated multispecialty group practice in Northern California. The odds ratio for developing squamous cell skin cancer among patients with connective tissue disease was 1.47 (95% CI, 1.14-1.90) (P=0.003) while the odds ratio for developing all non-melanoma skin cancer was 1.26 (95% CI, 1.08-1.49) (P=0.005). Patients on immunosuppressive medication for at least one year had an OR of 1.69 (95% CI, 1.16-2.45) of developing non-melanoma skin cancer (P=0.006) when controlled for age, race, gender, type of connective tissue disease, smoking status, and health care utilization. Our study shows an increased risk of non-melanoma skin cancer among patients with connective tissue disease. We also note that patients on immunosuppressive therapy for at least one year had an increased incidence of non-melanoma skin cancer. Further studies are needed to confirm these findings. J Drugs Dermatol. 2020;19(5):  doi:10.36849/JDD.2020.4781.

Density of Langerhans Cells in Nonmelanoma Skin Cancers: A Systematic Review.

Langerhans cells (LCs) are bone marrow-derived dendritic cells (DCs) that represent 2-3% of the entire cell population of the human skin, known to have an ability to present antigens to T lymphocytes. Moreover, there is evidence that LCs are probably capable of inducing the local cytotoxic type T-cell-mediated response against the tumour-associated antigens. In the past two decades, a dramatic increase has been noted in the incidence of basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). The purpose of this study was to critically assess the results of available studies quantitatively assessing the LCs in nonmelanoma skin cancers and try to establish a conclusion of its possible impact on their future treatment. The PubMed, EMBASE, and the Web of Science databases were searched, which returned 948 citations. After a thorough analysis of full article texts, 30 studies have been chosen, including 11 of the BCC, 12 of the SCC specimens, and 7 analysing both tumour types. There was an overall trend towards slightly higher numbers of LCs in BCC than in SCC; however, these tendencies were discrepant between the studies. We presume that such differences could be caused by various staining techniques with a broad spectrum of specificity, including anti-S100, anti-CD1a, and ATPase activity staining used for LCs identification. We hypothesise that as there is a high inconsistency between the results of the studies, as far as the densities of LCs observed in the specimens are concerned, it seems that the mechanism of the influence of LCs on the antitumoural immune response is complicated. Finally, as at present, there is a paucity of available risk scores for the recurrence or progression of BCC or SCC, the creation of classification stratifying that risk including the density of LCs could bring additional information both for the physician and the patient.

Superficial Basal Cell Cancers Demonstrate Higher Rates of Mixed Histology on High-Risk Anatomical Sites.

BACKGROUND: The Mohs Appropriate Use Criteria (MAUC) have come into question recently regarding the most appropriate treatment for superficial basal cell carcinoma (sBCC). At the heart of this debate is the limited body of evidence describing tumor behavior of sBCC based on clinical factors relevant to the MAUC. OBJECTIVE: To determine whether sBCC is more likely to harbor aggressive subtypes in high-risk anatomical locations and in immunocompromised patients. MATERIALS AND METHODS: A single institution retrospective review produced 133 evaluable Mohs cases performed on sBCC over a 10-year period. All slides from the respective cases were reviewed for the presence of histologic patterns other than known sBCC. Cases were then grouped by both MAUC anatomical zone (H, M, and L) and patient immune status for statistical analysis. RESULTS: A significantly higher rate of mixed histology (MH) was observed when comparing Zone H with Zone L across all patients, healthy patients, and immunocompromised patients. The same was true when comparing Zone M with Zone L for all patients and healthy patients (immunocompromised did not reach significance). CONCLUSION: The authors' data very clearly demonstrate a higher rate of MH in sBCC of the head and neck which provides strong support to the current MAUC scoring.

Clonal replacement of tumor-specific T cells following PD-1 blockade.

Immunotherapies that block inhibitory checkpoint receptors on T cells have transformed the clinical care of patients with cancer1. However, whether the T cell response to checkpoint blockade relies on reinvigoration of pre-existing tumor-infiltrating lymphocytes or on recruitment of novel T cells remains unclear2-4. Here we performed paired single-cell RNA and T cell receptor sequencing on 79,046 cells from site-matched tumors from patients with basal or squamous cell carcinoma before and after anti-PD-1 therapy. Tracking T cell receptor clones and transcriptional phenotypes revealed coupling of tumor recognition, clonal expansion and T cell dysfunction marked by clonal expansion of CD8+CD39+ T cells, which co-expressed markers of chronic T cell activation and exhaustion. However, the expansion of T cell clones did not derive from pre-existing tumor-infiltrating T lymphocytes; instead, the expanded clones consisted of novel clonotypes that had not previously been observed in the same tumor. Clonal replacement of T cells was preferentially observed in exhausted CD8+ T cells and evident in patients with basal or squamous cell carcinoma. These results demonstrate that pre-existing tumor-specific T cells may have limited reinvigoration capacity, and that the T cell response to checkpoint blockade derives from a distinct repertoire of T cell clones that may have just recently entered the tumor.

PD-L1 Detection-Pearls and Pitfalls Associated With Current Methodologies Focusing on Entities Relevant to Dermatopathology.

PD-L1 is a transmembrane glycoprotein with an extracellular as well as an intracellular cytoplasmic domain. Physiologically, it plays a pivotal role in regulating T-cell activation and tolerance. Many tumor cells have exploited this regulatory mechanism by overexpressing PD-L1 in an effort to escape immunologic surveillance. In this review, we parse the literature regarding the prognostic value of tumoral PD-L1 expression before discussing the various methodologies as well as the pearls and pitfalls associated with each for predicting response to anti-PD-1/PD-L1 therapies. Special attention is given to cutaneous entities in which PD-L1 expression has been documented with an emphasis on cutaneous malignancies that have seen the broadest applications of anti-PD-L1/PD-1 therapies. Currently, immunohistochemistry is the method that is most commonly used for detection of PD-L1. However, with the wide array of immunohistochemistry protocols and staining platforms available in the market, there seems to be different cutoffs not just for different entities but also for the same entity. This review is an attempt to address the need for standardization and validation of existing protocols for PD-L1 detection.