PD-L1 Expression is Increased in Metastasizing Squamous Cell Carcinomas and Their Metastases

Relationship Between PD-L1, PD-1, CD8 and Clinicopathological Factors in Primary SCCs

INTRODUCTION

Squamous cell carcinoma of the skin (SCCs) is the second most common skin cancer, with continuously increasing incidence. Programmed cell death ligand 1 (PD-L1), programmed cell death 1 receptor (PD-1), and CD8 expression in primary SCCs have not been described in many studies.

OBJECTIVE

We investigated the association between PD-L1, PD-1, CD8, and clinicopathological prognostic factors for recurrence, metastasis, and mortality of SCCs.

PATIENTS AND METHODS

Immunohistochemically stained sections of 100 primary SCCs divided into two groups according to diameter of the tumors (<20 mm and >20 mm) were assessed. Recombinant rabbit anti-PD-L1 antibody [SP142] - C-terminal, rabbit monoclonal anti-PD1 antibody [NAT105], and FLEX Mono Mo A-Hu CD8, cl C8/144B, RTU were used.

RESULTS

We did not establish statistically significant differences between PD-L1, PD-1, CD8 expression, and high-risk clinicopathological features - tumor size >20 mm, depth >6 mm, poor tumor cell differentiation, perineural/lymphovascular invasion, low/absent lymphocyte stromal reaction.

CONCLUSIONS

In primary SCCs, the expression of PD-L1, PD-1, and CD8 are not associated with high-risk clinicopathological factors. We suggest that these immunohistochemical markers are more significant in advanced cases and metastatic tissues.

The pleiotropic enhancer enh9 promotes cell proliferation and migration in non-small cell lung cancer via ERMP1 and PD-L1

Enhancers, cis-acting DNA elements for transcriptional regulation, are important regulators of cell identity and disease. However, of the hundreds of thousands of enhancers annotated in the human genome, only a few have been studied for their regulatory mechanisms and functions in cancer progression and therapeutic resistance. Here, we report the pleiotropy of one enhancer (named enh9) in both cell proliferation and migration in non-small cell lung cancer (NSCLC) cells. By integrating multi-genomic data, ERMP1 and PD-L1 were screened out as potential targets of enh9. CUT&Tag sequencing demonstrated that enh9 was involved in the genomic interactions between the transcription factor RELA and the promoters of ERMP1 and PD-L1. In addition, ERMP1 and PD-L1 were validated to be involved in cell proliferation and migration, respectively. Our study fully elucidated the function and transcriptional regulation mechanisms of enh9 in NSCLC. The exploration on enhancers is promising to provide new insights for cancer diagnosis and therapy.

Differential Immunoexpression of Inhibitory Immune Checkpoint Molecules and Clinicopathological Correlates in Keratoacanthoma, Primary Cutaneous Squamous Cell Carcinoma and Metastases

Beyond established anti-programmed cell death protein 1/programmed cell death ligand 1 immunotherapy, T-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibition motif domain (TIGIT) and its ligand CD155 are promising novel inhibitory immune checkpoint targets in human malignancies. Yet, in cutaneous squamous cell carcinoma, evidence on the collective expression patterns of these inhibitory immune checkpoints is scarce. Complete tumour sections of 36 cutaneous squamous cell carcinoma, 5 cutaneous metastases and 9 keratoacanthomas, a highly-differentiated, squamoproliferative tumour, with disparately benign biologic behaviour, were evaluated by immunohistochemistry for expression of programmed cell death ligand 1 (Tumor Proportion Score, Immune Cell Score), TIGIT, CD155 and CD8+ immune infiltrates. Unlike keratoacanthomas, cutaneous squamous cell carcinoma displayed a strong positive correlation of programmed cell death ligand 1 Tumor Proportion Score and CD115 expression (p < 0.001) with significantly higher programmed cell death ligand 1 Tumor Proportion Score (p < 0.001) and CD155 expression (p < 0.01) in poorly differentiated G3-cutaneous squamous cell carcinoma compared with keratoacanthomas. TIGIT+ infiltrates were significantly increased in programmed cell death ligand 1 Immune Cell Score positive primary tumours (p = 0.05). Yet, a strong positive correlation of TIGIT expression with CD8+ infiltrates was only detected in cutaneous squamous cell carcinoma (p < 0.01), but not keratoacanthomas. Providing a comprehensive overview on the collective landscape of inhibitory immune checkpoint expression, this study reveals associations of novel inhibitory immune checkpoint with CD8+ immune infiltrates and tumour differentiation and highlights the TIGIT/CD155 axis as a potential new target for cutaneous squamous cell carcinoma immunotherapy.

European consensus-based interdisciplinary guideline for invasive cutaneous squamous cell carcinoma. Part 1: Diagnostics and prevention-Update 2023

Invasive cutaneous squamous cell carcinoma (cSCC) is one of the most common cancers in white populations, accounting for 20% of all cutaneous malignancies. Overall, cSCC mostly has very good prognosis after treatment, with 5-year cure rates greater than 90%. Despite the overall favourable prognosis and the proportionally rare deaths, cSCC is associated with a high total number of deaths due to its high incidence. A collaboration of multidisciplinary experts from the European Association of Dermato-Oncology (EADO), the European Dermatology Forum (EDF), the European Society for Radiotherapy and Oncology (ESTRO), the European Union of Medical Specialists (UEMS), the European Academy of Dermatology and Venereology (EADV) and the European Organization of Research and Treatment of Cancer (EORTC), was formed to update recommendations on cSCC, based on current literature and expert consensus. Part 1 of the guidelines addresses the updates on classification, epidemiology, diagnosis, risk stratification, staging and prevention in immunocompetent as well as immunosuppressed patients.

The Current Treatment Landscape of Cutaneous Squamous Cell Carcinoma

Non-melanoma skin cancers (NMSCs) are the most common form of skin cancer worldwide. The global incidence of cutaneous squamous cell carcinoma (CSCC) is rising, with an estimated 2.4 million cases diagnosed in 2019. Chronic exposure to ultraviolet (UV) radiation is a major risk factor for developing CSCC. Most early-stage CSCCs are treated successfully with surgery or radiotherapy; however, locally advanced or metastatic disease can be associated with significant morbidity or mortality. Recently, the treatment paradigm for advanced CSCC has been revolutionised by the introduction of immunotherapy, which can achieve a response rate of approximately 50% with durable cancer control, and significant improvement in quality of life. With the regulatory approval of programmed death-1 (PD-1)-targeting drugs since 2018, immunotherapy is now recognised as the standard of care for first-line systemic therapy in advanced or metastatic CSCC.

Combined response of advanced cutaneous squamous cell carcinoma and renal cell carcinoma to immunotherapy: a case report

Immune checkpoint inhibitors have significantly improved the therapeutic scenario of many different advanced malignancies and could be an effective treatment strategy in synchronous or metachronous tumors. The authors describe the clinical case of a patient who experienced a long-lasting response of his metastatic renal cell carcinoma and an optimal response of his locally advanced cutaneous squamous cell carcinoma to immunotherapy. The systemic treatment was chosen based on a literature review of several clinical reports, since there was no prospective study on anti-PD-1 blockade activity in cutaneous squamous cell carcinoma when the patient started the treatment. This clinical case supports the growing evidence for immunotherapy as a valid treatment option across different types of advanced tumors.

Case report: A case of heterogeneity of the antitumor response to immune checkpoint inhibitors in a patient with relapsed hepatocellular carcinoma

The existence of tumor heterogeneity is widely recognized; however, heterogeneity of the antitumor response in multiple tumor nodules in the same patient has not been reported. Sintilimab, a monoclonal antiprogrammed cell death receptor-1 (PD-1) antibody, was used to treat patients with unresectable hepatocellular carcinoma (HCC). In the present study, we report a case of therapeutic heterogeneity in relapsed HCC with lung metastases. A 57-year-old female patient was diagnosed with HCC and underwent radical hepatectomy. One and a half years later, imaging scans found multiple metastatic tumors in the lung, which were accompanied by an increased α-fetoprotein (AFP) level. The patient then started to receive sintilimab. In the first 6 months after sintilimab treatment, all the metastatic nodules regressed gradually and ultimately disappeared, except for one nodule, which remained stable in the following 3 months. Finally, the patient underwent pulmonary lobectomy to remove the remaining nodule. Thereafter, follow-up visits showed the AFP level decreased to normal and imaging scans showed no signs of recurrence, confirming that the patient exhibited a clinically complete response. Pathological assessments showed that in the primary tumor site, the tumor comprised moderately differentiated HCC with a few infiltrated cytotoxic T cells and negative PD-L1 expression. While in the metastatic site, the nodule was composed of poorly differentiated HCC with cytotoxic T-cell infiltration with few cells inside the tumor and expressed PD-L1 in some areas of the tumor. There were dynamic alterations of PD-L1 expression and cytotoxic T-cell infiltration in the primary and relapsed HCC lesions after anti-PD-1 treatment. This case presented the heterogeneities of both the tumor microenvironment and the following antitumor response among the metastatic nodules in the same patient and revealed the importance of comprehensive therapy in cancer treatment.

Identifying Candidates for Immunotherapy among Patients with Non-Melanoma Skin Cancer: A Review of the Potential Predictors of Response

BACKGROUND

Non-melanoma skin cancer (NMSC) stands as an umbrella term for common cutaneous malignancies, including basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), together with rarer cutaneous cancers, such as Merkel cell carcinoma (MCC) and other forms of adnexal cancers. The majority of NMSCs can be successfully treated with surgery or radiotherapy, but advanced and metastatic stages may require systemic approaches such as immunotherapy with immune checkpoint inhibitors (ICIs).

SUMMARY

Since immunotherapy is not effective in all patients and can potentially lead to severe adverse effects, an important clinical question is how to properly identify those who could be suitable candidates for this therapeutic choice. In this paper, we review the potential features and biomarkers used to predict the outcome of ICIs therapy for NMSCs. Moreover, we analyze the role of immunotherapy in special populations, such as the elderly, immunocompromised patients, organ transplant recipients, and subjects suffering from autoimmune conditions.

KEY MESSAGES

Many clinical, serum, histopathological, and genetic features have been investigated as potential predictors of response in NMSCs treated with ICIs. Although this field of research is very promising, definitive, cost-effective, and reproducible biomarkers are still lacking and further efforts are needed to validate the suggested predictors in larger cohorts.

Investigating Cutaneous Squamous Cell Carcinoma in vitro and in vivo: Novel 3D Tools and Animal Models

Cutaneous Squamous Cell Carcinoma (cSCC) represents the second most common type of skin cancer, which incidence is continuously increasing worldwide. Given its high frequency, cSCC represents a major public health problem. Therefore, to provide the best patients’ care, it is necessary having a detailed understanding of the molecular processes underlying cSCC development, progression, and invasion. Extensive efforts have been made in developing new models allowing to study the molecular pathogenesis of solid tumors, including cSCC tumors. Traditionally, in vitro studies were performed with cells grown in a two-dimensional context, which, however, does not represent the complexity of tumor in vivo. In the recent years, new in vitro models have been developed aiming to mimic the three-dimensionality (3D) of the tumor, allowing the evaluation of tumor cell-cell and tumor-microenvironment interaction in an in vivo-like setting. These models include spheroids, organotypic cultures, skin reconstructs and organoids. Although 3D models demonstrate high potential to enhance the overall knowledge in cancer research, they lack systemic components which may be solved only by using animal models. Zebrafish is emerging as an alternative xenotransplant model in cancer research, offering a high-throughput approach for drug screening and real-time in vivo imaging to study cell invasion. Moreover, several categories of mouse models were developed for pre-clinical purpose, including xeno- and syngeneic transplantation models, autochthonous models of chemically or UV-induced skin squamous carcinogenesis, and genetically engineered mouse models (GEMMs) of cSCC. These models have been instrumental in examining the molecular mechanisms of cSCC and drug response in an in vivo setting. The present review proposes an overview of in vitro, particularly 3D, and in vivo models and their application in cutaneous SCC research.

Emerging precision diagnostics in advanced cutaneous squamous cell carcinoma

Advanced cutaneous squamous cell carcinoma (cSCC) encompasses unresectable and metastatic disease. Although immune checkpoint inhibition has been approved for this entity recently, a considerable proportion of cases is associated with significant morbidity and mortality. Clinical, histopathological, and radiological criteria are used for current diagnostics, classification, and therapeutic decision-making. The identification of complex molecular biomarkers to accurately stratify patients is a not yet accomplished requirement to further shift current diagnostics and care to a personalized precision medicine. This article highlights new insights into the mutational profile of cSCC, summarizes current diagnostic and therapeutic standards, and discusses emerging diagnostic approaches with emphasis on liquid biopsy and tumor tissue-based analyses.

Evidence-Based Consensus Recommendations for the Evolving Treatment of Patients with High-Risk and Advanced Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma is the second most common skin cancer in the United States. Currently, there is no standardized management approach for patients with cutaneous squamous cell carcinoma who develop metastatic or locally advanced disease and are not candidates for curative surgery or curative radiation. To address this issue, the Expert Cutaneous Squamous Cell Carcinoma Leadership program convened an expert steering committee to develop evidence-based consensus recommendations on the basis of a large, structured literature review. Consensus was achieved through modified Delphi methodology. The steering committee included five dermatologists, three medical oncologists, two head and neck surgeons, one radiation oncologist, and a patient advocacy group representative. The steering committee aligned on the following clinical topics: diagnosis and identification of patients considered not candidates for surgery; staging systems and risk stratification in cutaneous squamous cell carcinoma; the role of radiation therapy, surgery, and systemic therapy in the management of advanced disease, with a focus on immunotherapy; referral patterns; survivorship care; and inclusion of the patient's perspective. Consensus was achieved on 34 recommendations addressing 12 key clinical questions. The Expert Cutaneous Squamous Cell Carcinoma Leadership steering committee's evidence-based consensus recommendations may provide healthcare professionals with practically oriented guidance to help optimize outcomes for patients with advanced cutaneous squamous cell carcinoma.

Programmed Cell Death Protein 1/Programmed Cell Death Ligand-1 Axis activates Intracellular ERK Signaling in Tumor Cells to Mediate Poor Prognosis in T-cell Lymphoma

Purpose: To investigate the prognostic significance of programmed cell death ligand-1 (PD-L1) and phosphorylated ERK (p-ERK) and their interactions in T-cell lymphoma (TCL). Methods: The mRNA levels of PD-L1 and ERK in TCL samples were analyzed. Formalin-fixed paraffin-embedded tissues from 69 TCL patients were collected to detect the expression of PD-L1 and p-ERK by multiplexed immunofluorescence staining. The total PD-L1 and p-ERK was measured by western blotting, and membrane PD-L1 was determined using flow cytometry. Results: PD-L1 and ERK mRNA levels were significantly upregulated in TCL. The expression rates of PD-L1 and p-ERK were 52.2% and 27.5%, respectively. PD-L1 expression correlated with stage (R=0.304, P=0.011) and IPI score (R=0.313, P=0.009), and p-ERK expression correlated with stage (R=0.330, P=0.006) and IPI score (R=0.376, P=0.002). PD-L1 expression positively correlated with p-ERK expression (R=0.355, P=0.003). Patients with co-expression of PD-L1 and p-ERK had the worst overall survival (P=0.007). In three TCL cell lines with PD-L1 expression, we demonstrated that the expression of p-ERK was upregulated after stimulation with PD-1, suggesting that ERK signaling was activated. Conclusions: The PD-1/PD-L1 axis activates intracellular ERK signaling in tumor cells and that PD-L1, p-ERK or their combination are potential biomarkers for predicting the prognosis in TCL patients.

Histopathologic PD-L1 Tumor Expression and Prognostic Significance in Nonmelanoma Skin Cancers: A Systematic Review

ABSTRACT

PD-L1 and PD-1 inhibitors are being increasingly used to treat a variety of nonmelanoma skin cancers (NMSCs). This systematic review summarizes PD-L1 expression in NMSCs and determines its use for prognosis using targeted immunotherapy. A primary search of peer-reviewed English-language medical literature was conducted for studies on PD-L1 tumor expression in biopsied or excised NMSCs. Fifty-nine articles met criteria for inclusion. PD-L1 expression in advanced NMSCs ranged from 22%-89% for basal cell carcinomas, 42%-50% for Merkel cell carcinomas, and 26%-100% for squamous cell carcinomas. Study limitations included clone heterogeneity across studies, complicating comparison of PD-L1 expression. Differences were also noted in the selection of tumor reactivity threshold. We conclude that there is insufficient evidence to determine the prognostic significance of PD-L1 expression in NMSCs as a whole, but this remains a promising area. More investigation into the role of tumor PD-L1 as a biomarker for predicting clinical response to PD-L1 and PD-1 inhibitors in NMSCs is needed.

Mutually exclusive lymphangiogenesis or perineural infiltration in human skin squamous-cell carcinoma

Although tumor-associated lymphangiogenesis correlates with metastasis and poor prognosis in several cancers, it also supports T cell infiltration into the tumor and predicts favorable outcome to immunotherapy. The role of lymphatic vessels in skin squamous-cell carcinoma (sSCC), the second most common form of skin cancer, remains mostly unknown. Although anti-PD-1 therapy is beneficial for some patients with advanced sSCC, a greater understanding of disease mechanisms is still needed to develop better therapies.

Using quantitative multiplex immunohistochemistry, we analyzed sSCC sections from 36 patients. CD8+ T cell infiltration showed great differences between patients, whereby these cells were mainly excluded from the tumor mass. Similar to our data in melanoma, sSCC with high density of lymphatic endothelial cells showed increased CD8+ T cell density in tumor areas. An entirely new observation is that sSCC with perineural infiltration but without metastasis was characterized by low lymphatic endothelial cell density. Since both, metastasis and perineural infiltration are known to affect tumor progression and patients’ prognosis, it is important to identify the molecular drivers, opening future options for therapeutic targeting. Our data suggest that the mechanisms underlying perineural infiltration may be linked with the biology of lymphatic vessels and thus stroma.

Differential Molecular Expression Patterns Associated with Metastasis in Cutaneous Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

The majority of cutaneous squamous cell carcinomas are treated by surgical removal; however, approximately 4% of tumors will metastasize. Molecular expression testing may improve accuracy in estimating the prognosis and defining the mechanisms important in the disease progression, which may impact response to therapy. Using PubMed (MEDLINE) and EMBASE, a systematic review was performed to evaluate studies published from January 2005 to August 2019 reporting tumor protein or RNA expression along with either outcomes (metastasis or death) or a comparison of primary with metastatic tumor samples. Inclusion criteria were met by 45 studies containing 81 comparisons of 44 distinct proteins and 25 microRNAs. On meta-analysis of studies analyzing primary tumor samples in terms of later outcomes, high primary tumor expression of PD-L1 (OR = 2.34, 95% confidence interval = 1.09-5.02, P = 0.030), EGFR (OR = 2.57, 95% confidence interval = 1.24-5.33, P = 0.011), and podoplanin (OR = 2.33, 95% confidence interval = 1.00-5.41, P = 0.049) conferred increased odds for metastasis. In comparison, metastatic tissue was more likely to have a high expression of PD-L1 than primary tissue (OR = 3.13, 95% confidence interval = 1.00-9.75, P = 0.049). Further studies are needed to confirm whether testing for PD-L1, EGFR, and podoplanin expression aids in cutaneous squamous cell carcinomas prognostic estimation of metastasis or death or predicts response to therapy.

Antitumor Effects of Ursolic Acid through Mediating the Inhibition of STAT3/PD-L1 Signaling in Non-Small Cell Lung Cancer Cells

Targeted therapy based on natural compounds is one of the best approaches against non-small cell lung cancer. Ursolic acid (UA), a pentacyclic triterpenoid derived from medicinal herbs, has anticancer activity. Studies on the molecular mechanism underlying UA’s anticancer activity are ongoing. Here, we demonstrated UA’s anticancer activity and the underlying signaling mechanisms. We used Western blotting and real-time quantitative polymerase chain reaction for molecular signaling analysis. We also used in vitro angiogenesis, wound healing, and invasion assays to study UA’s anticancer activity. In addition, we used tumorsphere formation and chromatin immunoprecipitation assays for binding studies. The results showed that UA inhibited the proliferation of A549 and H460 cells in a concentration-dependent manner. UA exerted anticancer effects by inducing G0/G1 cell cycle arrest and apoptosis. It also inhibited tumor angiogenesis, migration, invasion, and tumorsphere formation. The molecular mechanism underlying UA activity involves UA’s binding to epidermal growth factor receptor (EGFR), reducing the level of phospho-EGFR, and thus inhibiting the downstream JAK2/STAT3 pathway. Furthermore, UA reduced the expressions of vascular endothelial growth factor (VEGF), metalloproteinases (MMPs) and programmed death ligand-1 (PD-L1), as well as the formation of STAT3/MMP2 and STAT3/PD-L1 complexes. Altogether, UA exhibits anticancer activities by inhibiting MMP2 and PD-L1 expression through EGFR/JAK2/STAT3 signaling.

Immune Checkpoint Blockade in Advanced Cutaneous Squamous Cell Carcinoma: What Do We Currently Know in 2020?

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer that predominantly arises in chronically sun-damaged skin. Immunosuppression, genetic disorders such as xeroderma pigmentosum (XP), exposure to certain drugs and environmental noxae have been identified as major risk factors. Surgical removal of cSCC is the therapy of choice and mostly curative in early stages. However, a minority of patients develop locally advanced tumors or distant metastases that are still challenging to treat. Immune checkpoint blockade (ICB) targeting CTLA-4, PD-L1 and PD-1 has tremendously changed the field of oncological therapy and especially the treatment of skin cancers as tumors with a high mutational burden. In this review, we focus on the differences between cSCC and cutaneous melanoma (CM) and their implications on therapy, summarize the current evidence on ICB for the treatment of advanced cSCC and discuss the chances and pitfalls of this therapy option for this cancer entity. Furthermore, we focus on special subgroups of interest such as organ transplant recipients, patients with hematologic malignancies, XP and field cancerization.

B7-H3 immune checkpoint expression is a poor prognostic factor in colorectal carcinoma

Although PD-1/PD-L1 immunotherapy has been used successfully in treating many cancers, metastatic colorectal cancer (CRC) patients are not as responsive. B7-H3 is a promising target for immunotherapy and we found it to have the highest expression among B7-CD28 family members in CRC. Thus, the aim of the present study was to investigate B7-H3 expression in a large CRC cohort. B7-H3, B7-H4, and PD-L1 protein levels and differential lymphocyte infiltration were evaluated in tissue microarrays from 805 primary tumors and matched metastases. The relationships between immune markers, patient characteristics, and survival outcomes were determined. B7-H3 (50.9%) was detected in more primary tumors than B7-H4 (29.1%) or PD-L1 (29.2%), and elevated B7-H3 expression was associated with advanced overall stage. Co-expression of B7-H3 only with B7-H4 or PD-L1 was infrequent in primary tumors (6.3%, 5.7%, respectively). Moreover, B7-H3 in primary tumors was positively correlated with their respective expression at metastatic sites (ρ = 0.631; p < 0.001). No significant relationships between B7-H4 and PD-L1 and survival were observed; however, B7-H3 overexpression in primary tumors was significantly related to decreased disease-free survival. A positive relationship between B7-H3 expression and high density CD45RO T cell was observed in primary tumors, whereas B7-H4 and PD-L1 overexpression were related to CD3 T-cell infiltration. In conclusion, compared with B7-H4 and PD-L1, B7-H3 expression exhibited a higher prevalence and was significantly related to aggressiveness, worse prognosis and CD45RO T-cell infiltration in primary tumors. Further exploration of this potential target of immunotherapy in CRC patients is warranted.

PD-L1 Influences Cell Spreading, Migration and Invasion in Head and Neck Cancer Cells

The programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) axis blockade has been implemented in advanced-stage tumor therapy for various entities, including head and neck squamous cell carcinoma (HNSCC). Despite a promising tumor response in a subgroup of HNSCC patients, the majority suffer from disease progression. PD-L1 is known to influence several intrinsic mechanisms in cancer cells, such as proliferation, apoptosis, migration and invasion. Here, we modulated PD-L1 expression in three HNSCC cell lines with differential intrinsic PD-L1 expression. In addition to an alteration in the epithelial-to-mesenchymal transition (EMT) marker expression, we observed PD-L1-dependent cell spreading, migration and invasion in a spheroid spreading assay on four different coatings (poly-L-lysine, collagen type I, fibronectin and Matrigel^®) and a chemotactic transwell migration/invasion assay. Furthermore, the overexpression of PD-L1 led to increased gene expression and small interfering ribonucleic acid (siRNA) knockdown and decreased gene expression of Rho-GTPases and related proteins in a RT² Profiler™ PCR Array. Rac1 and Rho-GTPase pulldown assays revealed a change in the activation state concordantly with PD-L1 expression. In summary, our results suggest a major role for PD-L1 in favoring cell motility, including cell spreading, migration and invasion. This is presumably caused by altered N-cadherin expression and changes in the activation states of small Rho-GTPases Rho and Rac1.

Molecular prediction of metastasis in cutaneous squamous cell carcinoma

PURPOSE OF REVIEW

Cutaneous squamous cell carcinoma (cSCC) is a highly prevalent malignancy frequently occurring on body surfaces chronically exposed to ultraviolet radiation. While a large majority of tumors remain localized to the skin and immediate subcutaneous tissue and are cured with surgical excision, a small subset of patients with cSCC will develop metastatic disease. Risk stratification for cSCC is performed using clinical staging systems, but given a high mutational burden and advances in targeted and immunotherapy, there is growing interest in molecular predictors of high-risk disease.

RECENT FINDINGS

Recent literature on the risk for metastasis in cSCC includes notable findings in genes involved in cell-cycle regulation, tumor suppression, tissue invasion and microenvironment, interactions with the host-immune system, and epigenetic regulation.

SUMMARY

cSCC is a highly mutated tumor with complex carcinogenesis. Regulators of tumor growth and local invasion are numerous and increasingly well-understood but drivers of metastasis are less established. Areas of importance include central system regulators (NOTCH, miRNAs), proteins involved in tissue invasion (podoplanin, E-cadherin), and targets of existing and emerging therapeutics (PD-1, epidermal growth factor receptor). Given the complexity of cSCC carcinogenesis, the use of machine learning algorithms and computational genomics may provide ultimate insight and prospective studies are needed to verify clinical relevance.

Programmed cell death ligand-1 and cytotoxic T cell infiltrates in metastatic cutaneous squamous cell carcinoma of the head and neck

BACKGROUND

Metastatic cutaneous squamous cell carcinoma (cSCC) carries a poor prognosis. Increased numbers of CD8+ cytotoxic T cells are associated with a favorable prognosis and programmed cell death receptor-1 is a suppressor of the CD8+ cytotoxic T cell response. We aim to define their expression in metastatic cutaneous squamous cell carcinoma.

METHODS

Cytotoxic T cell infiltrates and tumoral PD-L1 expression in lymph node metastases from patients with cSCC of the head and neck were analyzed.

RESULTS

High tumoral PD-L1 expression, intratumoral and peritumoral CD8+ cell density in metastases were significantly associated with poor primary tumor differentiation. Low PD-L1 expression, intratumoral and peritumoral CD8+ density were associated with lower grade primary tumor differentiation. Low PD-L1 expression correlated with disease progression.

CONCLUSIONS

Increased expression of PD-L1 correlates with increased CD8+ cell density. Increased expression of PD-L1 in poorly differentiated tumors may be more likely to benefit from anti PD-1/PD-L1 therapy.

A review of terms used to define cutaneous squamous cell carcinoma with a poor prognosis

Cutaneous squamous cell carcinoma (cSCC) is the second most common cancer in humans and its incidence is both underestimated and on the rise. cSCC is referred to in the literature as high-risk cSCC, locally advanced cSCC, metastatic cSCC, advanced cSCC, and aggressive cSCC. These terms can give rise to confusion and are not always well defined. In this review, we aim to clarify the concepts underlying these terms with a view to standardizing the description of this tumor, something we believe is necessary in light of the new drugs that have been approved or are in development for cSCC.

Cutaneous Squamous Cell Carcinoma: From Biology to Therapy

Cutaneous squamous cell carcinoma (CSCC) is the second most frequent cancer in humans and its incidence continues to rise. Although CSCC usually display a benign clinical behavior, it can be both locally invasive and metastatic. The signaling pathways involved in CSCC development have given rise to targetable molecules in recent decades. In addition, the high mutational burden and increased risk of CSCC in patients under immunosuppression were part of the rationale for developing the immunotherapy for CSCC that has changed the therapeutic landscape. This review focuses on the molecular basis of CSCC and the current biology-based approaches of targeted therapies and immune checkpoint inhibitors. Another purpose of this review is to explore the landscape of drugs that may induce or contribute to the development of CSCC. Beginning with the pathogenetic basis of these drug-induced CSCCs, we move on to consider potential therapeutic opportunities for overcoming this adverse effect.

European interdisciplinary guideline on invasive squamous cell carcinoma of the skin: Part 1. epidemiology, diagnostics and prevention

Invasive cutaneous squamous cell carcinoma (cSCC) is one of the most common cancers in the white populations, accounting for 20% of all cutaneous malignancies. Factors implicated in cSCC etiopathogenesis include ultraviolet radiation exposure and chronic photoaging, age, male sex, immunosuppression, smoking and genetic factors. A collaboration of multidisciplinary experts from the European Dermatology Forum (EDF), the European Association of Dermato-Oncology (EADO) and the European Organisation of Research and Treatment of Cancer (EORTC) was formed to update recommendations on cSCC classification, diagnosis, risk stratification, staging and prevention, based on current literature, staging systems and expert consensus. Common cSCCs are typically indolent tumors, and most have a good prognosis with 5-year cure rates of greater than 90%, and a low rate of metastases (<4%). Further risk stratification into low-risk or high-risk common primary cSCC is recommended based on proposed high-risk factors. Advanced cSCC is classified as locally advanced (lacSCC), and metastatic (mcSCC) including locoregional metastatic or distant metastatic cSCC. Current systems used for staging include the American Joint Committee on Cancer (AJCC) 8th edition, the Union for International Cancer Control (UICC) 8th edition, and Brigham and Women's Hospital (BWH) system. Physical examination for all cSCCs should include total body skin examination and clinical palpation of lymph nodes, especially of the draining basins. Radiologic imaging such as ultrasound of the regional lymph nodes, magnetic resonance imaging (MRI), computed tomography (CT), positron emission tomography-computed tomography (PET-CT) scans are recommended for staging of high-risk cSCC. Sentinel lymph node biopsy is currently not recommended. Nicotinamide, oral retinoids, and topical 5-FU have been used for the chemoprevention of subsequent cSCCs in high-risk patients but are not routinely recommended. Education about sun protection measures including reducing sun exposure, use of protective clothing, regular use of sunscreens and avoidance of artificial tanning, is recommended.

AXIN2 and SNAIL expression predict the risk of recurrence in cutaneous squamous cell carcinoma after Mohs micrographic surgery

Recurrence is a common complication observed during cutaneous squamous cell carcinoma (cSCC) treatment; however, biomarkers for predicting recurrence in cSCC remain unknown. The present study aimed to investigate the predictive value of axis inhibition protein 2 (AXIN2) and SNAIL expression in cSCC recurrence. AXIN2 and SNAIL expression was evaluated using immunohistochemistry in 111 cSCC tissue samples obtained from 18 patients who presented recurrence (recurrence interval, 1–91 months) and 93 patients who did not experience recurrence following Mohs micrographic surgery (MMS) during the follow-up period (156 months). Nomogram construction was performed using patients' clinicopathological characteristics and AXIN2 and SNAIL protein expression. The results demonstrated that high AXIN2 (histoscore >100) and SNAIL (histoscore >100) expression was detected in 35 and 44 cSCC tissues, respectively. Furthermore, the expression levels of AXIN2 and SNAIL were significantly associated in patients with cSCC (P=0.001). AXIN2 and SNAIL expression levels were significantly associated with tumor size (P=0.021 and P=0.044, respectively) and recurrence of cSCC (P=0.017 and P=0.042, respectively). In addition, the results of the Kaplan-Meier curve analysis revealed that recurrence-free survival was significantly associated with tumor size (P=0.025), differentiation status (P<0.001), AXIN2 expression (P=0.001) and SNAIL expression (P=0.001). Furthermore, the results of the multivariate analysis demonstrated that age (P=0.043), AXIN2 expression (P=0.001) and SNAIL expression (P=0.045) were independent risk factors for cSCC recurrence in the present cohort. A nomogram for predicting the 1-, 2-, 3-, and 5-year recurrence-free survival was developed for patients with cSCC by including independent risk factors with a concordance index of 0.75. The results suggested that high AXIN2 and SNAIL expression may be considered as potential risk factors for cSCC recurrence. This nomogram may therefore be useful to assess the probability of recurrence in patients with cSCC following MMS.

Driving innovation for rare skin cancers: utilizing common tumours and machine learning to predict immune checkpoint inhibitor response

Metastatic Merkel cell carcinoma (MCC) and cutaneous squamous cell carcinoma (cSCC) are rare and both show impressive responses to immune checkpoint inhibitor treatment. However, at least 40% of patients do not respond to these expensive and potentially toxic drugs. Development of predictive biomarkers of response and rational, effective combination treatment strategies in these rare, often frail patient populations is challenging. This review discusses the pathophysiology and treatment of MCC and cSCC, with a particular focus on potential biomarkers of response to immunotherapy, and discusses how transfer learning using big data collected from patients with common tumours can be used in combination with deep phenotyping of rare tumours to develop predictive biomarkers and elucidate novel treatment targets.

•

Metastatic Merkel cell carcinoma and cutaneous squamous cell carcinoma are rare tumours.

•

Immunotherapy gives impressive responses but most patients do not survive long term.

•

Small patient numbers prevent extensive biomarker research in clinical trials.

•

Pooled data from common and rare tumours can be used to train neural networks.

•

In rare cancers, neural networks can help identify biomarkers and novel treatment targets.

PD-L1/PD1 Expression, Composition of Tumor-Associated Immune Infiltrate, and HPV Status in Conjunctival Squamous Cell Carcinoma

Purpose

Conjunctival squamous cell carcinoma (SCC), a type of ocular surface neoplasia, is primarily treated by surgical resection and topical immuno- or chemotherapy. Metastatic disease may be treated with systemic chemo- or immunotherapy, albeit with variable response. The purpose of this study was to determine whether immune checkpoint blockade might be considered in the management of conjunctival SCC.

Methods

In this retrospective study, we evaluated tumor programmed death-ligand 1 (PD-L1) expression, high-risk human papillomavirus (HPV) status, and immunohistochemical expression of cluster of differentiation 3 (CD3), cluster of differentiation 8 (CD8), and programmed death 1 (PD1) in tumor-associated immune infiltrate in a series of 31 conjunctival SCCs.

Results

PD-L1 expression in ≥1% of tumor cells was noted in 14 conjunctival SCCs (47%) and was more prevalent in invasive than in situ SCC and among tumors with higher American Joint Committee on Cancer (AJCC) T category (≥T3 versus ≤T2). The density of CD3-positive T cells was higher in primary than recurrent tumors and higher in invasive than in situ tumors. Density of CD3-positive and CD8-positive T cells was higher in higher AJCC stage tumors. Density of CD8-positive T cells was higher in HPV-positive than HPV-negative tumors. PD-L1 expression correlated with a higher density of CD3-, CD8-, and PD1-positive cells in the tumor-associated immune infiltrate but not with HPV status.

Conclusions

Our findings demonstrate that PD-L1 is expressed in almost half of conjunctival SCCs. The density of tumor-associated immune cells correlated with invasive SCC, stage, and HPV status in conjunctival SCC. Our findings support further studies to establish the potential application of immune checkpoint blockade in the management of conjunctival SCC.

Heterogeneity of PD-L1 expression and CD8 tumor-infiltrating lymphocytes among subtypes of cutaneous adnexal carcinomas

BACKGROUND

Adnexal carcinomas are rare and heterogeneous skin tumors, for which no standard treatments exist for locally advanced or metastatic tumors.

AIM OF THE STUDY

To evaluate the expression of PD-L1 and CD8 in adnexal carcinomas, and to study the association between PD-L1 expression, intra-tumoral T cell CD8+ infiltrate, and metastatic evolution.

MATERIALS AND METHODS

Eighty-three adnexal carcinomas were included. Immunohistochemistry using anti-PD-L1 monoclonal antibodies (E1L3N and 22C3) and CD8 was performed. PD-L1 expression in tumor and immune cells, and CD8+ tumor-infiltrating lymphocyte (TIL) density were analyzed semi-quantitatively.

RESULTS

Among the 60 sweat gland, 18 sebaceous and 5 trichoblastic carcinomas, 11% expressed PD-L1 in ≥ 1% tumor cells, more frequently sweat gland carcinomas (13%, 8/60) including apocrine carcinoma (40%, 2/5) and invasive extramammary Paget disease (57%, 4/7). Immune cells expressed significantly more PD-L1 than tumor cells (p < 0.01). Dense CD8+ TILs were present in 60% trichoblastic, 43% sweat gland, and 39% sebaceous carcinomas. CD8+ TILs were associated with PD-L1 expression by tumor cells (p < 0.01). Thirteen patients out of 47 developed metastases (27%) with a median follow-up of 30.5 months (range 7-36). Expression of PD-L1 by tumor cells was associated with the development of metastasis in univariate analysis (HR 4.0, 95% CI 1.1-15, p = 0.0377) but not in multivariate analysis (HR 4.1, 95% CI 0.6-29, p = 0.15).

CONCLUSION

PD-L1 expression is highly heterogeneous among adnexal carcinoma subtypes, higher in apocrine carcinoma and invasive extramammary Paget disease, and associated with CD8+ TILs. Our data suggest the interest of evaluating anti-PD1 immunotherapy in advanced or metastatic cutaneous adnexal carcinoma.

The Role of the Immune System in Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer. In immunosuppressed populations it is a source of considerable morbidity and mortality due to its enhanced recurrence and metastatic potential. In common with many malignancies, leucocyte populations are both protective against cancer development and also play a role in 'sculpting' the nascent tumor, leading to loss of immunogenicity and tumor progression. UV radiation and chronic viral carriage may represent unique risk factors for cSCC development, and the immune system plays a key role in modulating the response to both. In this review, we discuss the lessons learned from animal and ex vivo human studies of the role of individual leucocyte subpopulations in the development of cutaneous SCC. We then discuss the insights into cSCC immunity gleaned from studies in humans, particularly in populations receiving pharmacological immunosuppression such as transplant recipients. Similar insights in other malignancies have led to exciting and novel immune therapies, which are beginning to emerge into the cSCC clinical arena.

Chromosome 3q arm gain linked to immunotherapy response in advanced cutaneous squamous cell carcinoma

AIMS

The activity that the immune checkpoint inhibitor (ICI) cemiplimab has recently demonstrated has led to a paradigm shift in the management of patients with advanced cutaneous squamous cell carcinoma (cSCC). To identify predictive biomarkers of response to ICIs in advanced cSCC, we studied 33 patients who received ICI therapy at the Dana-Farber/Harvard Cancer Center (DF/HCC) and analysed sequencing data for a subset of these patients.

METHODS

We collected clinical data using electronic health records and genomic data using the institutional OncoPanel platform of the DF/HCC. We compared tumour genomics with data from previously sequenced cSCC cohorts.

RESULTS

We observed high tumour mutational burden regardless of smoking status and response to ICI and longer median overall survival among those patients who achieved an ICI response. We compared the genetic data from our cohort with data from other cohorts that included fewer patients with distant metastatic disease. Although our cohort had a similar genetic landscape to those of comparator cohorts, mutations in PIK3C2B were more common in our study. In our cohort, copy number alterations (CNAs) in the 3q chromosomal arm appeared to predict response to ICI therapy.

CONCLUSION

CNAs in the 21-27 bands of chromosome arm 3q, a region that includes PIK3CA, ETV5 and BCL6, may represent predictors of response to ICI and may be candidates for drug targeting in combination or sequence with ICI agents.