Cutaneous Squamous Cell Carcinoma in the Age of Immunotherapy

The hidden Australian skin cancer epidemic, high-risk cutaneous squamous cell carcinoma: a narrative review

Deaths from non-melanoma skin cancers (NMSCs) have almost doubled in Australia in recent years. Cutaneous squamous cell carcinoma (cSCC) constitutes approximately 20% of NMSCs, but is responsible for most of the deaths. Most skin cancers are easy to diagnose and treat and therefore cSCC are often trivialised; however, there is a high-risk subgroup of cSCC (HRcSCC) that is associated with a high risk of metastasis and death. The definition of early HRcSCC and our ability to identify them is evolving. Many significant prognostic factors have been identified, but a universally accepted prognostic index does not exist. Guidelines for workup, treatment, and follow-up leave many important decisions open to broad interpretation by the treating physician or multidisciplinary team. Some of the treatments used for metastatic cSCC are not supported by robust evidence and the prognosis of metastatic cSCC is guarded. In this review, we highlight the rapid rise in NMSC deaths and discuss some of the deficiencies in our knowledge of how to define, diagnose, stage, and manage HRcSCC.

Competing-risks analysis for evaluating the prognosis of patients with microinvasive cutaneous squamous cell carcinoma based on the SEER database

BACKGROUND

Utilizing the traditional Cox regression model to identify the factors affecting the risk of mortality due to microinvasive cutaneous squamous cell carcinoma (micSCC) may produce skewed results. Since cause-specific mortality can guide clinical decision-making, this study employed the Fine-Gray model based on the Surveillance, Epidemiology, and End Results (SEER) database to identify significant predictive variables for the risk of micSCC-related mortality.

METHODS

This study used the information of patients with micSCC who were listed in the SEER database during 2000-2015. Cox regression and Fine-Gray models were utilized for the multivariable analysis, and Gray's test and the cumulative incidence function were used for the univariable analyses.

RESULTS

There were 100 patients who died from other reasons and 38 who died from micSCC among the 1259 qualified patients with micSCC. Most were female, white, married, had localized metastasis, etc. According to the univariable Gray's test (P < 0.05), the cumulative incidence rate for events of interest was strongly associated with age, sex, marital status, American Joint Committee on Cancer staging, radiation status, summary stage, chemotherapy status, surgery status, and tumor size. Multivariable Cox regression analysis and multivariable competing-risks analysis indicated that age, tumor size, and income were independent risk variables for the prognosis of patients with micSCC. In both age and tumor size variables, the competing-risks model showed a slight decrease in the hazard ratio and a slight narrowing of the 95% confidence interval compared with the Cox regression model. However, this pattern is not evident in the income variable.

CONCLUSIONS

This study established a Fine-Gray model for identifying the independent risk factors that influence the risk of mortality among patients with micSCC. This study uncovers that, in the context of competing risks, age, tumor size, and income serve as independent risk factors influencing the risk of mortality due to micSCC among patients. Our findings have the potential to provide more accurate risk assessments for patient outcomes and contribute to the development of individualized treatment plans.

Health-Related Quality of Life with Pembrolizumab in Patients with Locally Advanced or Recurrent or Metastatic Cutaneous Squamous Cell Carcinoma: KEYNOTE-629

INTRODUCTION

At first interim analysis of KEYNOTE-629, health-related quality of life (HRQoL) with pembrolizumab was stable or improved over 48 weeks in recurrent or metastatic (R/M) cutaneous squamous cell carcinoma (cSCC). HRQoL results from the second interim analysis in R/M or locally advanced (LA) cSCC are presented.

METHODS

Patients received pembrolizumab 200 mg every 3 weeks for ≤ 2 years. Change in EORTC Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and EQ-5D-5L scores were exploratory end points. Primary analysis was performed at week 12 to ensure adequate completion/compliance. Descriptive analyses were also conducted through weeks 48 and 75 for the LA and R/M cohorts, respectively.

RESULTS

At data cutoff (29 July 2020), mean scores in the LA cohort (n = 47) were stable from baseline to week 12 for EORTC QLQ-C30 global health status (GHS)/quality of life (QoL) (-0.27 points [95% confidence interval (CI) -10.93 to 10.39]), physical functioning (-1.29 points [95% CI  -8.77 to 6.19]), and EQ-5D-5L visual analog scale (2.06 [95% CI -7.70 to 11.82]). HRQoL remained stable through week 48 in the LA cohort; 76.6% and 74.5% of patients had improved or stable GHS/QoL and physical functioning scores, respectively. HRQoL continued to show stability or improvement through week 75 in the R/M cohort (n = 99); 71.7% and 64.6% of patients had improved or stable GHS/QoL and physical functioning scores, respectively.

CONCLUSIONS

Pembrolizumab has demonstrated antitumor activity and manageable safety. The current analysis shows pembrolizumab treatment preserved HRQoL. Collectively, these results support pembrolizumab as standard of care for LA or R/M cSCC.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03284424-September 15, 2017.

A chlorin e6 derivative-mediated photodynamic therapy inhibits cutaneous squamous cell carcinoma cell proliferation via Akt/mTOR signaling pathway

BACKGROUND AND OBJECTIVES

Although most cutaneous squamous cell carcinoma (cSCC) cases are generally nonlethal and manageable with surgical excision, there ares till significant hazards for patients who are ineligible for surgical resection. We sought to find a suitable and effective treatment for cSCC.

METHODS

We modified chlorin e6 by adding a hydrogen chain with a six-carbon ring to the benzene ring and named this new photosensitizer as STBF. We first investigated the fluorescence characteristics, cellular uptake of STBF and subcellular localization. Next, cell viability was detected by CCK-8 assay and the TUNEL staining was performed. Akt/mTOR-related proteins were examined by western blot.

RESULTS

STBF-photodynamic therapy (PDT) inhibits cSCC cells viability in a light dose dependent manner. The antitumor mechanism of STBF-PDT might be due to the suppression of the Akt/mTOR signaling pathway. Further animal investigation determined that STBF-PDT led to a marked reduction in tumor growth.

CONCLUSIONS

Our results suggest that STBF-PDT exerts significant therapeutic effects in cSCC. Thus, STBF-PDT is expected to be a promising method for the treatment of cSCC and the photosensitizer STBF may be destined for a wider range of applications in photodynamic therapy.

Proline-rich 11 (PRR11) promotes the progression of cutaneous squamous cell carcinoma by activating the EGFR signaling pathway

Cutaneous squamous cell carcinoma (cSCC) is one of the most common skin malignancies, and its incidence rate is increasing worldwide. Proline-rich 11 (PRR11) has been reported to be involved in the occurrence and development of various tumors. However, the role of PRR11 in cSCC remains unknown. In the present study, we observed upregulated expression of PRR11 in cSCC tissues and cell lines. Knockdown of PRR11 in the cSCC cell lines A431 and SCL-1 inhibited cell proliferation by inducing cell cycle arrest during the G1/S phase transition, promoted cell apoptosis, and reduced cell migration and invasion in vitro. Conversely, overexpression of PRR11 promoted cell proliferation, decreased cell apoptosis, and enhanced cell migration and invasion. PRR11 knockdown also inhibited cSCC tumor growth in a mouse xenograft model. Mechanistic investigations by RNA sequencing revealed that 891 genes were differentially expressed genes between cells with PRR11 knockdown and control cells. Enrichment analysis of different genes showed that the epidermal growth factor receptor (EGFR) signaling pathway was the top enriched pathway. We further validated that PRR11 induced EGFR pathway activity, which contributed to cSCC progression. These data suggest that PRR11 may serve as a novel therapeutic target in cSCC.

NPTX2 Promotes Epithelial-Mesenchymal Transition in Cutaneous Squamous Cell Carcinoma through METTL3-Mediated N6-Methyladenosine Methylation of SNAIL

Cutaneous squamous cell carcinoma (cSCC) is the second most common type of skin cancer. NPTX2, a member of the neuronal pentraxin family, is reported to play inconsistent roles in different cancers. The role and mechanism of NPTX2 in cSCC remain unclear. In this study, we found that NPTX2 was overexpressed in both skin lesions and cell lines of cSCC. In vitro studies showed that NPTX2 facilitated cell proliferation, migration, invasion, colony formation, and epithelial‒mesenchymal translation in A431 and SCL-1 cells. NPTX2 interacted with METTL3, increased METTL3 expression, and improved N6-methyladenosine modification in cSCC cell lines. Mechanistically, NPTX2 facilitated epithelial‒mesenchymal translation by promoting METTL3-mediated N6-methyladenosine of SNAIL. METTL3 knockdown and N6-methyladenosine inhibition reversed the impacts of NPTX2 overexpression on cSCC cells. In vivo studies verified the role of NPTX2 as an oncogene in cSCC. Therefore, NPTX2 may be a potential therapeutic target for cSCC.

Squamous Cell Carcinoma Arising from Chronic Osteomyelitis in the Extremities: Treatment Approach and Oncological Outcomes-A Systematic Review of the Literature

Aims

In chronic osteomyelitis-derived squamous cell carcinoma, what are the demographic and clinical variables, risk factors associated with worse outcomes, and results of treatment modalities used?

Methods

A systematic review was performed using PubMed and EMBASE. Articles were evaluated for inclusion and exclusion criteria, and for quality analysis. PRISMA guidelines were applied. Demographic and clinical data and therapeutic approaches were presented narratively and in descriptive statistics registered at PROSPERO.

Results

Most patients were male (40/49), trauma was the most common etiology (27/36), and about half of all SCC were in the tibia (25/48). Amputation was the main definitive treatment (42/47). Adjuvant treatments were not analyzed. Well-differentiated SCC accounted for 58.3% (21/36) of all tumors. Bone invasion was described in 82.8% (24/29); recurrence, in 7.7% (3/39); and metastasis, in 7.7% (3/39). Recurrence and metastasis occurred more frequently when bone invasion was present (p = 0.578 and p = 0.646, respectively). SCC with lymph node involvement showed a higher tendency to metastasize (p = 0.377). Compared with limb salvage, amputation was associated with a tendency for less recurrence (p = 0.312) and longer survival (p = 0.219).

Conclusions

COM-derived SCC mostly occurs after trauma and is usually located in the tibia. Bone invasion is common, and patients predominantly undergo amputation. This treatment is associated with a trend toward higher survival, compared to limb salvage.

Features and clinical significance of tertiary lymphoid structure in cutaneous squamous cell carcinoma

BACKGROUND

Tertiary lymphoid structure (TLS) plays an important role in anti-tumor immunity, largely reflecting the prognosis. However, its clinical implication in cutaneous squamous cell carcinoma (cSCC) remains unknown.

OBJECTIVES

To explore the features of TLS in cSCC and its association with clinicopathological characteristics.

METHODS

Two independent RNA-seq data of cSCC were used to investigate the tumor immune microenvironment, as well as TLS-related chemokines and cytokines. The density and location of TLSs were assessed in a total of 82 cSCC patients, and the clinicopathologic association was examined.

RESULTS

Bioinformatics analysis showed that a large amount of immune cell infiltration and significant up-regulation of TLS-related chemokines were observed in cSCC. Histologically, TLSs appeared as highly organized structures in 72 (87.8%) cases with different levels of density and maturation, among which 14 cases were in low-density group and 58 cases were in high-density group. Clinically, the presence of TLS was prominently associated with better degree of histopathological grades and higher level of sun exposure. Furthermore, the presence of intratumoral TLS was associated with lower lymphovascular invasion.

CONCLUSIONS

TLS is highly organized in cSCC, and the presence of TLS is a positive prognostic factor for cSCC, which will provide a theoretical basis for the future diagnostic and therapeutic value in cSCC.

A tEMTing target? Clinical and experimental evidence for epithelial-mesenchymal transition in the progression of cutaneous squamous cell carcinoma (a scoping systematic review)

Cutaneous squamous cell carcinoma (cSCC) is a disease with globally rising incidence and poor prognosis for patients with advanced or metastatic disease. Epithelial-mesenchymal transition (EMT) is a driver of metastasis in many carcinomas, and cSCC is no exception. We aimed to provide a systematic overview of the clinical and experimental evidence for EMT in cSCC, with critical appraisal of type and quality of the methodology used. We then used this information as rationale for potential drug targets against advanced and metastatic cSCC. All primary literature encompassing clinical and cell-based or xenograft experimental studies reporting on the role of EMT markers or related signalling pathways in the progression of cSCC were considered. A screen of 3443 search results yielded 86 eligible studies comprising 44 experimental studies, 22 clinical studies, and 20 studies integrating both. From the clinical studies a timeline illustrating the alteration of EMT markers and related signalling was evident based on clinical progression of the disease. The experimental studies reveal connections of EMT with a multitude of factors such as genetic disorders, cancer-associated fibroblasts, and matrix remodelling via matrix metalloproteinases and urokinase plasminogen activator. Additionally, EMT was found to be closely tied to environmental factors as well as to stemness in cSCC via NFκB and β-catenin. We conclude that the canonical EGFR, canonical TGF-βR, PI3K/AKT and NFκB signalling are the four signalling pillars that induce EMT in cSCC and could be valuable therapeutic targets. Despite the complexity, EMT markers and pathways are desirable biomarkers and drug targets for the treatment of advanced or metastatic cSCC.

Ultrastructural Features of Keratoacanthoma—Clinical Implications

Over the years, keratoacanthomas have been described as some of the most common skin lesions with the potential for malignant transformation, thus constituting an important risk factor for the development of squamous cell carcinoma. The quantification of the risk of malignant transformation is conditioned by the clinical–morphological and etiopathogenic variability of these lesions, with a negative impact on diagnostic and therapeutic management. In this sense, the main objective of this research is to characterize from an ultrastructural perspective the specific tumour microenvironment, by using a technique with a higher resolution power than photon microscopy. Keratoacanthoma lesions from 25 patients were excised from healthy tissue and then processed by classical electron microscopy and examined with the Philips CM100 microscope. The electron microscopic study revealed structural details suggestive of malignant transformation, capturing changes at both cytoplasmic and membranous levels. The identification and description of the ultrastructural morphological substrate favouring the evolution and progression of the studied lesions correlates directly with the improvement of the prognosis and quality of life of these patients.

Molecular Mechanisms of Cutaneous Squamous Cell Carcinoma

Non-melanoma skin cancers are cutaneous malignancies representing the most common form of cancer in the United States. They are comprised predominantly of basal cell carcinomas and squamous cell carcinomas (cSCC). The incidence of cSCC is increasing, resulting in substantial morbidity and ever higher treatment costs; currently in excess of one billion dollars, per annum. Here, we review research defining the molecular basis and development of cSCC that aims to provide new insights into pathogenesis and drive the development of novel, cost and morbidity saving therapies.

Elevated Levels of Soluble CTLA-4, PD-1, PD-L1, LAG-3 and TIM-3 and Systemic Inflammatory Stress as Potential Contributors to Immune Suppression and Generalized Tumorigenesis in a Cohort of South African Xeroderma Pigmentosum Patients

Xeroderma Pigmentosum (XP), an autosomal recessive disorder characterized by ultraviolet radiation-induced abnormalities of DNA excision and repair pathways is associated with early development of cutaneous cancers. Intracellular oxidative stress has also been proposed as a contributor to the occurrence of skin cancers. However, little is known about the possible augmentative contributions of chronic inflammation, immune suppression and oxidative stress to the pathogenesis of malignancies associated with other subtypes of XP. This has been addressed in the current study, focused on the measurement of systemic biomarkers of inflammation, immune dysfunction and oxidative damage in XP patients, consisting of XP-C, XP-D and XP-E cases, including those XP-C cases who had already developed multiple skin malignancies. The inflammatory biomarker profile measured in XP patients and healthy control subjects included the cytokines, interleukins (ILs)-2, -4, -6, -10, interferon-γ (IFN- γ) and tumor-necrosis factor-α (TNF-α), the acute phase reactant, C-reactive protein (CRP), and cotinine (as an objective indicator of smoking status). Immune suppression was detected according to the levels of five soluble inhibitory immune checkpoint proteins (CTLA-4, PD-1, PD-L1, LAG-3 and TIM-3), as well as those of vitamin D, while oxidative stress was determined according to the circulating levels of the DNA adduct, 8-hydroxy-2-deoxyguanosine (8-OH-dG). These various biomarkers were measured in plasma using immunofluorimetric, nephelometric and ELISA procedures. Significant elevations in IL-6 (P<0.01) and TNF-α (P<0.0001), but none of the other cytokines, as well as increased levels of all five soluble inhibitory immune checkpoints (P=0.032-P=0.0001) were detected in the plasma of the XP patients. C-reactive protein and vitamin D were increased and decreased, respectively (both P<0.0001), while only one participant had an elevated level of plasma cotinine. Surprisingly, the levels of 8-OH-dG were significantly (P=0.0001) lower in the group of XP patients relative to a group of healthy control subjects. The findings of increased levels of pro-inflammatory cytokines and, in particular, those of the soluble immune checkpoints, in the setting of decreased vitamin D and moderately elevated levels of CRP in XP patients suggest a possible secondary role of ongoing, inflammatory stress and immune suppression in the pathogenesis of XP-associated malignancies.

Integrin αE(CD103)β7 in Epithelial Cancer

Interactions of both the innate and the adaptive immune system with tumors are complex and often influence courses and therapeutic treatments in unanticipated ways. Based on the concept that CD8+T cells can mediate important antitumor effects, several therapies now aim to amplify their specific activity. A subpopulation of CD8+ tissue-resident T lymphocytes that express the αE(CD103)β7 integrin has raised particular interest. This receptor presumably contributes to the recruitment and retention of tumor-infiltrating immune cells through interaction with its ligand, E-cadherin. It appears to have regulatory functions and is thought to be a component of some immunological synapses. In TGF-rich environments, the αE(CD103)β7/E-cadherin-interaction enhances the binding strength between tumor cells and infiltrating T lymphocytes. This activity facilitates the release of lytic granule contents and cytokines as well as further immune responses and the killing of target cells. Expression of αE(CD103)β7 in some tumors is associated with a rather favorable prognosis, perhaps with the notable exception of squamous cell carcinoma of the skin. Although epithelial skin tumors are by far the most common tumors of fair-skinned people, there have been very few studies on the distribution of αE(CD103)β7 expressing cells in these neoplasms. Given this background, we describe here that αE(CD103)β7 is scarcely present in basal cell carcinomas, but much more abundant in squamous cell carcinomas with heterogeneous distribution. Notwithstanding a substantial number of studies, the role of αE(CD103)β7 in the tumor context is still far from clear. Here, we summarize the essential current knowledge on αE(CD103)β7 and outline that it is worthwhile to further explore this intriguing receptor with regard to the pathophysiology, therapy, and prognosis of solid tumors.

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.