Advanced cutaneous squamous cell carcinoma: how is it defined and what new therapeutic approaches are available?

Cemiplimab for metastatic squamous cell carcinoma of the orbit, periocular adnexa, and thigh

The current case presentation highlights the potential of cemiplimab, a programmed cell death protein-1 (PD-1) inhibitor, as first-line treatment for periocular metastatic cutaneous squamous cell carcinoma (SCC) without requiring curative surgery or radiotherapy. A 64-year-old male presented with a progressing 4.5 × 3.0 cm left upper eyelid lesion initially diagnosed as psoriasis. Work-up revealed cutaneous SCC with tumor invasion into extraconal fat and lacrimal gland, and metastasis to the left parotid lymph node. The patient also presented with a suspicious lesion on his left medial thigh found to be a second primary on pathology. To avoid orbital exenteration and treat the multifocal disease, the patient was started on intravenous cemiplimab immunotherapy. Following six doses, repeated FGD-PET-CT revealed a complete response of the left eyelid lesion and residual low-grade hypermetabolic activity of the left medial thigh lesion. Biopsy confirmed chronic inflammation and fibrosis with no signs of malignancy. This unique case with dual primary cutaneous SCC provides support for cemiplimab in treating locally invasive periocular SCC, and potentially abrogating the need for highly morbid exenteration procedures to preserve binocular vision.

The crucial roles of m6A RNA modifications in cutaneous cancers: Implications in pathogenesis, metastasis, drug resistance, and targeted therapies

N6-methyladenosine (m6A) is the most abundant internal modification on RNA. It is a dynamical and reversible process, which is regulated by m6A methyltransferase and m6A demethylase. The m6A modified RNA can be specifically recognized by the m6A reader, leading to RNA splicing, maturation, degradation or translation. The abnormality of m6A RNA modification is closely related to a variety of biological processes, especially the occurrence and development of tumors. Recent studies have shown that m6A RNA modification is involved in the pathogenesis of skin cancers. However, the precise molecular mechanisms of m6A-mediated cutaneous tumorigenesis have not been fully elucidated. Therefore, this review will summarize the biological characteristics of m6A modification, its regulatory role and mechanism in skin cancers, and the recent research progress of m6A-related molecular drugs, aiming to provide new ideas for clinical diagnosis and targeted therapy of cutaneous cancers.

Sex as a Predictor of Response to Immunotherapy in Advanced Cutaneous Squamous Cell Carcinoma

Approximately 3-5% of patients with cutaneous squamous cell carcinoma (CSCC) develop advanced disease, accounting for roughly 1% of all cancer deaths in Australia. Immunotherapy has demonstrated significant clinical benefit in advanced CSCC in several key phase II studies; however, there are limited data for patients treated outside of clinical trials. This is particularly relevant in advanced CSCC, which is most often seen in elderly patients with significant comorbidities. Thus, we aim to describe our experience with immunotherapy in a cohort of patients with advanced CSCC in Australia. We retrospectively reviewed all advanced CSCC patients treated with immunotherapy within the Illawarra and Shoalhaven Local Health District. Among the 51 patients treated with immunotherapy, there was an objective response rate (ORR) of 53% and disease control rate (DCR) of 67%. Our most significant predictor of response was sex, with male patients more likely to have better responses compared to female patients (DCR 85% vs. 41%, p < 0.0001), as well as improved progression-free survival (HR 4.6, 95%CI 1.9-10.8, p = 0.0007) and overall survival (HR 3.0, 95%CI 1.3-7.1, p = 0.006). Differential expression analysis of 770 immune-related genes demonstrated an impaired CD8 T-cell response in female patients. Our observed ORR of 53% is similar to that described in current literature with durable responses seen in the majority of patients.

Cemiplimab-induced cytokine-release syndrome: second case reported and review of the literature

Cemiplimab, a human monoclonal antibody directed against PD-1, has provided more options in the treatment of locally advanced or metastatic cutaneous squamous-cell carcinoma at an unresectable state. Immune checkpoint inhibitors can induce several unfavorable reactions generally referred to as immune-related adverse effects. Cytokine-release syndrome is an immune-related adverse event that is infrequent and not well known. Diagnosis is difficult because of the unspecific symptoms (e.g., fever, hypotension) but it can also be life threatening. The authors report the case of a 62-year-old treated by cemiplimab for a cutaneous squamous-cell carcinoma of the diaper fold with iliac and inguinal lymph node extension. He presented with severe cytokine-release syndrome, concluding with the discontinuation of cemiplimab.

PD-L1 Biomolecules Associated with Clinical Features in Non-Melanoma Skin Cancer

Background

Increasing evidence has indicated that several B7 family members play critical roles in the progress of many cancers. However, the clinical significance of the B7 family in cutaneous squamous cell carcinoma (cSCC) is still elusive. The purpose of this study is to investigate the potential role of B7-H1 biomolecules (PD-L1) in regulating the tumorigenesis and progression of cSCC, the most common non-melanoma skin cancer.

Methods

We collected transcriptome data of cSCC patients from TCGA databases (n = 496) and subjected the transcription data to bioinformatical analysis. Differential expression of B7-H1 genes with a grade-dependent pattern was identified. We collected paraffin sections of skin squamous carcinoma and analyzed by immunohistochemical staining. We further examined the PD-L1 levels of CD14+ cells in peripheral blood of each cSCC patient and normal subjects by flow cytometry.

Results

It was found that higher expression of PD-L1 was associated with poor prognosis of cSCC patients and shorter overall survival. These observations were further verified in the clinical paraffin sections and in peripheral blood T cells.

Conclusion

Our study reveals that PD-L1 is a potential prognostic marker in clinical prognosis for cSCC patients and could be valuable for cSCC treatment.

Recent Advances in Immunotherapy for Patients with Head and Neck Cutaneous Squamous Cell Carcinoma

Simple Summary

Cutaneous squamous cell cancer is a form of skin cancer, which is typically found in older fair-skinned individuals with frequent sun exposure. Most patients present with limited disease and can be treated with a combination of surgery and/or radiation with favorable outcomes. A small percentage of patients present with more aggressive, widespread disease. Immunotherapy has dramatically improved outcomes and has become the preferred treatment option for these patients. In this review article, the rationale for using immunotherapy in patients with squamous cell skin cancer is discussed. A summary of the new treatment options currently being explored is also provided.

Abstract

Cutaneous squamous cell carcinoma (CSCC) is the second most common non-melanoma skin cancer. A majority of patients present with localized disease, but some can present with locally advanced or metastatic disease. Most of these advanced cases occur in the anatomical head and neck region and are associated with more aggressive disease, necessitating prompt and effective treatment. Prior to the emergence of immunotherapy, systemic treatment options were limited to platinum-based chemotherapy and salvaged with targeted epidermal growth factor therapy. These therapies were associated with poor efficacy and increased toxicity in an often frail, older population. Immunotherapy has dramatically improved outcomes in this patient population due to its favorable side effect profile, durable treatment response, and improved overall outcomes. In this review, an overview of the recent advances of immunotherapy in the management of CSCC in the anatomical head and neck region is provided, with a focus on advanced presentations.

Anti-PD-1 for the treatment of advanced cutaneous squamous cell carcinoma in elderly patients: a French multicenter retrospective survey

Background

Anti-PD1 agents are currently recommended as first-line treatment in advanced cutaneous squamous cell carcinoma (acSCC) by updated European guidelines. Although acSCC frequently affects elderly patients with multiple comorbidities, this subset of patients is often excluded of registration clinical trials.

Purpose

To assess anti-PD-1 efficacy and safety in elderly acSCC patients in real-life conditions and describe this specific population with oncogeriatric evaluation tools.

Methods

A multicenter retrospective study including acSCC patients at least 70 years old treated with PD-1 inhibitors was conducted in French referral centers. The primary endpoint was the overall response rate (ORR). Secondary endpoints included safety data, time to response (TTR), duration of response (DOR), overall survival (OS), and progression-free survival (PFS).

Results

63 patients were included. ORR was 57.1% (95% CI 44.0–69.5), median TTR and DOR were 3 and 5.5 months respectively. Median OS was not reached (95% CI 12.5 months-not reached) at data cut-off after a median follow-up of 8 months while median PFS was 8 months. (95% CI 5 months-not reached). Grade 3–5 adverse effects occurred in 47.6% of patients. 41.3% of patients experienced degradation of ECOG performance status during anti-PD-1 treatment. Nutritional state worsened in 27% of patients and 57.1% lost weight during treatment.

Conclusion

In this particular subset of acSCC patients PD-1 inhibitors obtain results similar to those obtained in younger populations included in pivotal clinical trials, with acceptable safety. A specific oncogeriatric evaluation at treatment initiation and during follow-up appears important in this setting most notably to help manage toxicity.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00432-022-04246-0.

Immunotherapy for the Treatment of Squamous Cell Carcinoma: Potential Benefits and Challenges

Melanoma and nonmelanoma skin cancers (NMSCs) are recognized as among the most common neoplasms, mostly in white people, with an increasing incidence rate. Among the NMSCs, squamous cell carcinoma (SCC) is the most prevalent malignancy known to affect people with a fair complexion who are exposed to extreme ultraviolet radiation (UVR), have a hereditary predisposition, or are immunosuppressed. There are several extrinsic and intrinsic determinants that contribute to the pathophysiology of the SCC. The therapeutic modalities depend on the SCC stages, from actinic keratosis to late-stage multiple metastases. Standard treatments include surgical excision, radiotherapy, and chemotherapy. As SCC represents a favorable tumor microenvironment with high tumor mutational burden, infiltration of immune cells, and expression of immune checkpoints, the SCC tumors are highly responsive to immunotherapies. Until now, there are three checkpoint inhibitors, cemiplimab, pembrolizumab, and nivolumab, that are approved for the treatment of advanced, recurrent, or metastatic SCC patients in the United States. Immunotherapy possesses significant therapeutic benefits for patients with metastatic or locally advanced tumors not eligible for surgery or radiotherapy to avoid the potential toxicity caused by the chemotherapies. Despite the high tolerability and efficiency, the existence of some challenges has been revealed such as, resistance to immunotherapy, less availability of the biomarkers, and difficulty in appropriate patient selection. This review aims to accumulate evidence regarding the genetic alterations related to SCC, the factors that contribute to the potential benefits of immunotherapy, and the challenges to follow this treatment regime.

Infrequent liver injury from cemiplimab in patients with advanced cutaneous squamous cell carcinoma

Aim: To describe the incidence and outcomes of liver injury in patients with advanced cutaneous squamous cell carcinoma (cSCC) receiving cemiplimab. Methods: Charts of cSCC patients receiving cemiplimab between 28 September 2018 and 14 July 2020 were reviewed. Liver injury was determined using laboratory criteria, and causality assessment was completed. Results: Of 39 cemiplimab-treated patients, four (10.3%) developed liver injury. Two cases of hepatotoxicity were attributed to immune-mediated liver injury caused by cemiplimab and the two other cases were attributed to other causes. The four patients with liver injury had tumor responses and survival similar to those of the patients without liver injury. Conclusion: Liver injury arising during cemiplimab therapy is mild and infrequent in cSCC patients. Due to its favorable safety profile, cemiplimab should be considered in patients with cSCC and pre-existing liver disease.

Lidocaine represses proliferation and cisplatin resistance in cutaneous squamous cell carcinoma via miR-30c/SIRT1 regulation

This study aimed to determine the effects of lidocaine on cell proliferation and cisplatin resistance in A431 human cutaneous squamous cell carcinoma (cSCC) cells and elucidate the underlying mechanism. Cell proliferation, colony numbers, and cisplatin resistance were determined in A431 or cisplatin-resistant A431 (A431-R) cells that were first transfected with miR-30c-inhibitor or miR-30c-mimic, respectively, and then treated with different concentrations of lidocaine, cisplatin, or both. The expression levels of miR-30c and Sirtuin 1 (SIRT1) in A431 and A431-R cells were determined by quantitative real-time polymerase chain reaction and Western blotting. Lidocaine suppressed A431 cell proliferation and cisplatin resistance in a dose- and time-dependent manner via the miR-30c/SIRT1 pathway. MiR-30c overexpression also suppressed cell proliferation and cisplatin resistance in A431 cells by directly targeting and downregulating SIRT1, thus enhancing the protective effects of lidocaine. Conversely, SIRT1 upregulation or miR-30c inhibition antagonized the inhibitory effects of lidocaine. Our results suggest that lidocaine may suppress the progression of cSCC by activating the miR-30c/SIRT1 pathway, indicating its promising potential as a treatment strategy for cSCC.

Identifying candidates for immunotherapy with cemiplimab to treat advanced cutaneous squamous cell carcinoma: an expert opinion

Cutaneous squamous cell carcinoma (CSCC) is the second most common skin malignancy in white-skinned populations. Only a minority of patients (<5%) develop advanced disease, but this is often difficult to treat and characterised by a poor prognosis. Cemiplimab, a fully human IgG4 monoclonal antibody against programmed cell death-1 receptor, is indicated for advanced (i.e. locally advanced or metastatic) CSCC. Although the definition of metastatic CSCC is clear, there is currently no agreed definition of locally advanced CSCC. In recent guidelines, locally advanced CSCC was described as non-metastatic CSCC that is unlikely to be cured with surgery, radiotherapy or combination treatment. A multi-disciplinary advisory group of Italian CSCC experts was convened to develop criteria to assist in identifying appropriate candidates for cemiplimab therapy in advanced CSCC, based on the literature and clinical experience. In locally advanced CSCC, absolute, or mandatory, criteria for the use of cemiplimab are deep invasion, multiple lesions without defined margins, inadequate surgical excision margins and multiple recurrences, whereas relative criteria include large lesions, in critical or functionally significant areas and that are surgically complex. In addition, physicians should consider patient willingness/preferences (an absolute criterion), and their age and health status/comorbidities (relative criteria). It is hoped that these proposed absolute and relative criteria will help guide rational identification of patients who will receive maximum benefit from immunotherapy, while more clinical data accumulate.

Current Surgical Therapy of Locally Advanced cSCC: From Patient Selection to Microsurgical Tissue Transplant. Review

Among the non-melanoma skin cancers (NMSC) the squamous cell carcinoma (SCC) is one of the most challenging for the surgeon. Local aggressiveness and a tendency to metastasize to regional lymph nodes characterize the biologic behavior. The variants locally advanced and metastatic require wide excision and node dissection. Such procedures can be extremely detrimental for patients. The limit of the surgery can be safely pushed forward with a multidisciplinary approach. The concept of skin oncoplastic surgery, the ablative procedures and the reconstructive options (skin graft, pedicled flap, microsurgical free flap) are discussed together with a literature review.

Update of advanced cutaneous squamous cell carcinoma

The incidence of cutaneous squamous cell carcinoma (cSCC) is rapidly increasing. A growing part of this patient group is formed by immunocompromised patients, for example organ-transplant recipients (OTR). Although over 90% of the cSCC show a relatively harmless clinical behaviour, there is also a chance of developing advanced cSCC and metastases. Locally advanced cSCC are defined as cSCC that have locally advanced progression and are no longer amenable to surgery or radiation therapy. Better understanding of the clinical behaviour of cSCC is essential to discriminate between low- and high-risk cSCC. Staging systems are important and have recently been improved. Genetic characterisation of SCC will likely become an important tool to help distinguish low and high-risk cSCC with an increased potential to metastasise in the near future. Available treatments for high-risk and advanced cSCC include surgery, radiotherapy, chemotherapy and targeted therapy with epidermal growth factor receptors inhibitors. Anti-PD-1 antibodies show promising results with response rates of up to 50% in both locally advanced and metastatic cSCC but, in its present form, is not suitable for OTR.

Real world data of cemiplimab in locally advanced and metastatic cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) has an overall favourable outcome, except for patients with an advanced stage disease. The programmed death protein-1 (PD-1) inhibitor cemiplimab has been approved for use in advanced cSCC. We report clinical outcomes from the named patient programme-compassionate use of cemiplimab for patients with advanced cSCC in Italy.

METHODS

This is a retrospective, observational, multicentre study. We analysed medical records of patients with advanced cSCC treated with cemiplimab between May 2019 and February 2020 in 17 referral Italian centres. We assessed the safety profile according to the Common Terminology Criteria for Adverse Events, version 5.0 (CTCAE v 5.0), the clinical activity in terms of response rate, clinical benefit and duration of response and baseline clinical-pathologic characteristics associated with response.

RESULTS

131 patients were included, with a median age of 79 years. Of them, 9.2% had a concurrent chronic lymphoproliferative disease and 8.5% a concomitant autoimmune disease. Some 42.7% of the total patients had at least one treatment-related adverse events (AEs); out of above, 9.2% had grade 3-4 adverse events, and there were two fatal adverse events. The overall response rate (ORR) was 58%, and the disease control rate (DCR) was 71.7%. Cutaneous squamous cell carcinomas (cSCCs) arising on the head and neck area (p = 0.007) and haemoglobin values in normal range (p = 0.034) were significantly associated with a better response, while cSCCs on the genitalia (p = 0.041), treatment with any systemic antibiotic within 1 month of cemiplimab initiation (p = 0.012), performance status ≥1 (p = 0.012), chronic corticosteroids therapy (p = 0.038), previous radiation therapy to lymph nodes (p = 0.052) and previous chemotherapy (p = 0.0020) were significantly associated with a worse response.

CONCLUSIONS

Our real-world study showed safety and effectiveness results comparable to those obtained in clinical trials. We identified some clinical and biochemical factors potentially associated with response to cemiplimab.

Immunotherapy for the Treatment of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (CSCC) accounts for approximately 20% of all keratinocytic tumors. In most cases, the diagnosis and treatments are made on small, low-risk lesions. However, in about 5% of cases, CSCC may present as either locally advanced or metastatic (i.e. with locoregional lymph nodes metastases or distant localizations). Prior to the introduction of immunotherapy in clinical practice, the standard treatment of advanced CSCC was not clearly defined, and up to 60% of patients received no systemic therapy. Thanks to a strong pre-clinical rationale, clinical trials led to the FDA (Food and Drug Administration) and EMA (European Medicines Agency) registration of cemiplimab, a PD-1 inhibitor that achieved encouraging results in terms of objective response, overall survival, and quality of life. Subsequently, the anti-PD-1 pembrolizumab received the approval for the treatment of advanced CSCC by the FDA only. In this review, we will focus on the definition of advanced CSCC and on the current and future therapeutic options, with a particular regard for immunotherapy.

Adjuvant therapy for high-risk cutaneous squamous cell carcinoma: 10-year review

Standard of care for high-risk cutaneous squamous cell carcinoma (cSCC) is surgical excision of the primary lesion with clear margins when possible, and additional resection of positive margins when feasible. Even with negative margins, certain high-risk factors warrant consideration of adjuvant therapy. However, which patients might benefit from adjuvant therapy is unclear, and supporting evidence is conflicting and limited to mostly small retrospective cohorts. Here, we review literature from the last decade regarding adjuvant radiation therapy and systemic therapy in high-risk cSCC, including recent and current trials and the role of immune checkpoint inhibitors. We demonstrate evidence gaps in adjuvant therapy for high-risk cSCC and the need for prognostic tools, such as gene expression profiling, to guide patient selection. More large-cohort clinical studies are needed for collecting high-quality, evidence-based data for determining which patients with high-risk cSCC may benefit from adjuvant therapy and which therapy is most appropriate for patient management.

Local Chemotherapy as an Adjuvant Treatment in Unresectable Squamous Cell Carcinoma: What Do We Know So Far?

Background: Squamous cell carcinoma (SCC) is one of the most common cancers involving skin and oral mucosa. Although this condition's gold-standard treatment is the surgical removal of the lesions, the physician must propose alternative treatments in some cases due to the patient's ineligibility for surgery. Among the available alternative therapies, local chemotherapy may represent an initial treatment in combination with radiotherapy or systemic chemotherapy due to the low frequency of side-effects and the lack of necessity for expensive devices. Methods: In this paper, we review all available literature in various databases (PubMed, Scopus-Embase, Web of Science), proposing local chemotherapy as a treatment for cutaneous and oral SCC. Exclusion criteria included ocular lesions (where topical treatments are common), non-English language, and non-human studies. Results: We included 14 studies in this review. The majority were case reports and case series describing the treatment of non-resectable localized SCC with either imiquimod or 5-fluorouracil. We also analyzed small studies proposing combination treatments. Almost all studies reported an excellent clinical outcome, with a low risk of relapses in time. Conclusions: Resection of the lesion remains the gold-standard treatment for SCC. When this approach is not feasible, local chemotherapy may represent a treatment alternative, and it may also be associated with radiotherapy or systemic chemotherapy.

Grape Seed Proanthocyanidins (GSPs) Inhibit the Development of Cutaneous Squamous Cell Carcinoma by Regulating the hsa_circ_0070934/miR-136-5p/PRAF2 Axis

Background

Grape seed proanthocyanidins (GSPs) have been shown to inhibit the progression of many cancers, including cutaneous squamous cell carcinoma (CSCC). Circular RNA (circRNA) is a key regulator for cancer progression. However, it is unclear whether GSPs can mediate the progression of CSCC by regulating circRNA.

Methods

Quantitative real-time PCR was conducted to determine the expression of hsa_circ_0070934, microRNA (miR)-136-5p and prenylated Rab acceptor family 2 (PRAF2). MTT assay and colony formation assay were used to assess cell proliferation. Cell cycle process and apoptosis were detected by flow cytometry, and cell migration and invasion were measured by transwell assay. Western blot analysis was utilized to examine protein expression. In addition, dual-luciferase reporter assay and RIP assay were used to evaluate the interaction between miR-136-5p and hsa_circ_0070934 or PRAF2. Subcutaneous xenograft models were constructed to explore the function of GSPs on CSCC tumor growth in vivo.

Results

GSPs could reduce hsa_circ_0070934 expression and inhibit CSCC cell proliferation, cell cycle process, migration, invasion, while promote apoptosis. Overexpressed hsa_circ_0070934 could reverse the suppressive effect of GSPs on CSCC cell progression. MiR-136-5p could be sponged by hsa_circ_0070934, and its overexpression also abolished the positively regulation of hsa_circ_0070934 on the progression of GSPs-induced CSCC cells. PRAF2 was a target of miR-136-5p, and its expression could be decreased by GSPs and increased by hsa_circ_0070934. The inhibitory effect of miR-136-5p on CSCC cell progression could be reversed by PRAF2 overexpression. Additionally, GSPs also could inhibit CSCC tumor growth in vivo.

Conclusion

Our data showed that GSPs regulated the hsa_circ_0070934/miR-136-5p/PRAF2 axis to restrain CSCC progression.

Topical arginase inhibition decreases growth of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinomas (cSCC) are among the most commonly diagnosed malignancies, causing significant morbidity and mortality. Tumor-associated macrophage (TAM) expression of arginase is implicated in tumor progression, and therapeutic use of arginase inhibitors has been studied in various cancers. However, investigating potential cSCC immunotherapies including arginase inhibition in pre-clinical models is hampered by the lack of appropriate tumor models in immunocompetent mice. PDV is a cSCC cell line derived from chemical carcinogenesis of mouse keratinocytes. PDVC57 cells were derived from a PDV tumor in C57BL/6 (B6) mice. Unlike PDV, PDVC57 tumors grow consistently in B6 mice, and have increased TAMs, decreased dendritic and T cell intra-tumor infiltration. Arginase inhibition in cSCC tumors using Nω-hydroxy-nor-arginine (nor-NOHA) reduced tumor growth in B6 mice but not immunodeficient Rag1-deficient mice. nor-NOHA administration increased dendritic and T cell tumor-infiltration and PD-1 expression. The combination of nor-NOHA and anti-PD-1 therapy with nivolumab enhanced anti-PD-1 therapeutic efficacy. This study demonstrates the therapeutic potential of transcutaneous arginase inhibition in cSCC. A competent immune microenvironment is required for tumor growth inhibition using this arginase inhibitor. Synergistic co-inhibition of tumor growth in these results, supports further examination of transcutaneous arginase inhibition as a therapeutic modality for cSCC.

Exosomal Circular RNA RNA-seq Profiling and the Carcinogenic Role of Exosomal circ-CYP24A1 in Cutaneous Squamous Cell Carcinoma

Objective: Aberrantly expressed exosomal circular RNAs (circRNAs) have been reported in various human cancers. Nevertheless, it remains elusive in cutaneous squamous cell carcinoma (cSCC). Herein, based on RNA-seq, we systematically uncovered the expression and implication of exosomal circRNAs in cSCC.

Methods: Plasma exosomes derived from cSCC and healthy subjects were characterized by nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), and western blot. Differentially expressed exosomal circular RNAs (circRNAs) were screened by RNA-seq analysis, which were validated by RT-qPCR. Among them, the biological structure of circ-CYP24A1 was validated by Sanger sequencing and RNase R digestion. Si-circ-CYP24A1 was transfected into exosomes, followed by incubation with A431 and SCL-1 cells. Then, viability, apoptosis, migration, and invasion were evaluated by CCK-8, TUNEL staining and migration assays.

Results: This study identified 25 up- and 76 down-regulated exosomal circRNAs in cSCC than healthy subjects. Among them, circulating circ-CYP24A1 was confirmed to be up-regulated in cSCC. Circ-CYP24A1 had a covalently closed circular structure and was not sensitive to RNase R digestion. After incubation with si-circ-CYP24A1-transfected exosomes, proliferation, migration, and invasion were lowered while apoptosis was enhanced in A431 and SCL-1 cells. Meanwhile, si-circ-CYP24A1-transfected exosomes significantly decreased the expression of downstream targets CDS2, MAVS, and SOGA in cSCC cells.

Conclusion: Collectively, our study identified that targeting exosomal circ-CYP24A1 could suppress cSCC progression by weakening tumor malignant behaviors, which might provide a promising therapeutic target and non-invasive diagnostic biomarker for cSCC.

Identifying an lncRNA-Related ceRNA Network to Reveal Novel Targets for a Cutaneous Squamous Cell Carcinoma

Simple Summary

The exact functions and molecular mechanism of lncRNAs, acting as competitive endogenous RNAs in a cutaneous squamous cell carcinoma, remain unexplored. The present study was conducted to identify the differentially expressed lncRNAs and mRNAs and establish the lncRNA-related competing endogenous RNA networks associated with a cutaneous squamous cell carcinoma. A competing endogenous RNA network consisting of 137 miRNA-lncRNA and 221 miRNA-mRNA pairs was constructed. As for the functional analysis of the mRNAs in the network, a FoxO signaling pathway, an autophagy and cellular senescence were the top enrichment terms based on the Kyoto Encyclopedia of Genes and Genomes analysis. We identified five core mRNAs and built a core mRNA-associated competing endogenous RNA network. Finally, one lncRNA HLA-F-AS1 and three mRNAs named AGO4, E2F1 and CCND1 in the core mRNA-associated competing endogenous RNA network were validated with the same expression patterns. The core mRNAs and their associated lncRNAs may provide potential therapeutic targets for cutaneous squamous cell carcinomas.

Abstract

A cutaneous squamous cell carcinoma (cSCC) derived from keratinocytes is the second most common cause of non-melanoma skin cancer. The accumulation of the mutational burden of genes and cellular DNA damage caused by the risk factors (e.g., exposure to ultraviolet radiation) contribute to the aberrant proliferation of keratinocytes and the formation of a cSCC. A cSCC encompasses a spectrum of diseases that range from recursor actinic keratosis (AK) and squamous cell carcinoma (SCC) in situ (SCCIS) to invasive cSCCs and further metastatic SCCs. Emerging evidence has revealed that lncRNAs are involved in the biological process of a cSCC. According to the ceRNA regulatory theory, lncRNAs act as natural miRNA sponges and interact with miRNA response elements, thereby regulating the mRNA expression of their down-stream targets. This study was designed to search for the potential lncRNAs that may become potential therapeutic targets or biomarkers of a cSCC. Considering the spirit of the study to be adequately justified, we collected microarray-based datasets of 19 cSCC tissues and 12 normal skin samples from the GEO database (GSE42677 and GSE45164). After screening the differentially expressed genes via a limma package, we identified 24 differentially expressed lncRNAs (DElncRNAs) and 3221 differentially expressed mRNAs (DEmRNAs). The miRcode, miRTarBase, miRDB and TargetScan databases were used to predict miRNAs that could interact with DElncRNAs and DEmRNAs. A total of 137 miRNA-lncRNA and 221 miRNA-mRNA pairs were retained in the ceRNA network, consisting of 31 miRNAs, 11 DElncRNAs and 155 DEmRNAs. For the functional analysis, the top enriched biological process was enhancer sequence-specific DNA binding in Gene Ontology (GO) terms. The FoxO signaling pathway, autophagy and cellular senescence were the top enrichment terms based on a Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The combination of a STRING tool and Cytoscape software (plug-in MCODE) identified five core mRNAs and built a core mRNA-associated ceRNA network. The expression for five identified core mRNAs and their related nine lncRNAs was validated using the external dataset GSE7553. Finally, one lncRNA HLA-F-AS1 and three mRNAs named AGO4, E2F1 and CCND1 were validated with the same expression patterns. We speculate that lncRNA HLA-F-AS1 may sponge miR-17-5p or miR-20b-5p to regulate the expression of CCND1 and E2F1 in the cSCC. The present study may provide potential diagnostic and therapeutic targets for cSCC patients.

Cemiplimab for locally advanced cutaneous squamous cell carcinoma: safety, efficacy, and position in therapy panel

INTRODUCTION

Locally advanced cutaneous squamous cell carcinoma (lacSCC) is rare. Approximately one-fourth of the cases are observed among immunocompromised patients, in particular in solid organ transplant recipients (OTRs). LacSCC has a very poor prognosis. Surgery with or without radiotherapy remains the golden standard of treatment for cSCC. However, in advanced cases, there is a medical need for alternative treatment options. Classic systemic treatments include chemotherapy and/or EGFR inhibitors. Recently the effectiveness of programmed cell death protein-1 (PD-1) inhibitors has been demonstrated for lacSCC. Cemiplimab is a recombinant IgG4 human monoclonal antibody against the PD-1 protein for the intravenous treatment of lacSCC.

AREAS COVERED

The principal studies evaluating the efficacy and safety of cemiplimab for lacSCC are presented.

EXPERT OPINION

Cemiplimab is the first anti-PD-1 antibody that was FDA (2018) and EMA (2019) approved as a systemic treatment for lacSCC and/or metastatic cSCC when curative surgery or radiotherapy is no longer amenable. For this situation, experts currently recommend cemiplimab as a first-line systemic alternative. As cemiplimab therapy is potentially associated with a risk of organ graft rejection, pros and cons should be evaluated for every individual OTR patient with lacSCC.

Challenges and new perspectives in the treatment of advanced cutaneous squamous cell carcinoma

Despite the overall excellent survival rates in patients affected by early cutaneous squamous cell carcinoma (CSCC), advanced forms of CSCC are associated with high patient mortality. To date, only limited therapeutic modalities have been implemented, including chemotherapy and radiotherapy. Systemic therapy was enriched by the addition of epidermal growth factor receptor inhibitors (EGFRi) in the last years. Unfortunately, the overall outcome of all these therapeutic strategies remains poor, therefore important unmet clinical needs persist. Thanks to a better understanding of the biology of advanced CSCC, new treatment options are now available. This article presents the current definition of advanced CSCC along with actual therapeutic options and discusses the strengths and limitations of a new promising systemic approach, which involves the use of immune checkpoint inhibitors.