Merkel Cell Carcinoma: Epidemiology, Target, and Therapy

Merkel cell carcinoma in Taiwan: a subset is chronic arsenicism-related, and the Merkel cell polyomavirus-negative cases are pathologically distinct from virus-related cases with a poorer outcome

Merkel cell carcinoma (MCC) is a rare primary neuroendocrine carcinoma of the skin, more frequent in the West than in the East. The pathogenesis is complex, with Merkel cell polyomavirus (MCPyV) and ultraviolet (UV) light being reported to play important roles. In this retrospective study of MCC cases from Taiwan, we analysed the prognostic significance of pathological features and the status of MCPyV and retinoblastoma (Rb) expression. We retrospectively collected MCC cases from five hospitals in Taiwan from 1994 to 2022. We examined the clinical and pathological features, performed immunohistochemical studies for the large T antigen of MCPyV and Rb, and reviewed medical records from electronic data. Disease-specific survival was estimated by using the Kaplan-Meier estimate and compared between subgroups using log-rank test. The clinical and pathological features and the immunohistochemical profiles between subgroups were compared using the Fisher exact test for categorical variables. The 38 patients were mostly (71%) males, with a median age of 79. In 22 (58%) patients, the tumours occurred in sun-exposed areas. Clinically, five (13%) patients had chronic arsenicism. Histopathologically, 11 (29%) cases showed combined tumours (MCC with squamous cell carcinoma or Bowen disease/squamous carcinoma in situ). Seventeen (45%) cases were positive for MCPyV, whereas all combined tumours were negative. MCPyV-negative MCC displayed distinctive pathological features, including epidermal changes, presence of an intraepidermal MCC component, linear or single-file growth pattern, and pleomorphic nuclei. Immunohistochemically, 59% (22/37) MCC cases showed complete loss of Rb protein expression, more frequent in MCPyV-unrelated (p<0.001) and combined (p=0.014) cases, ​but without statistical significance among patients with chronic arsenicism, sun exposure, or disease-specific survival. MCPyV-negative cases exhibited a shorter disease-specific survival than MCPyV-positive cases (median overall survival 13 months vs not reached; p=0.041). MCPyV-negative or combined MCCs were associated with a higher disease-specific mortality and poorer prognosis. MCCs occurring in sun-shielded sites, MCPyV-negativity, and combined tumours correlated with a higher disease-specific mortality and a poorer prognosis by multivariable Cox proportional hazard model. The occurrence of MCCs with arsenic exposure was also identified. Our study showed that MCPyV-negative MCC cases in Taiwan exhibited distinctive pathological features and a poorer outcome than MCPyV-related cases. We also confirmed an association of chronic arsenicism with MCC, which might be considered as the third pathogenetic factor after MCPyV and UV light. Further studies including epidemiological and genetic investigations are warranted to elucidate the pathogenesis of MCC in Taiwan, particularly the significance of chronic arsenicism.

Advancing Treatment Options for Merkel Cell Carcinoma: A Review of Tumor-Targeted Therapies

Although rare, Merkel cell carcinoma (MCC) is a highly aggressive and increasingly prevalent neuroendocrine cancer of the skin. While current interventions, including surgical resection, radiation, and immunotherapy have been employed in treating many patients, those who remain unresponsive to treatment are met with sparse alternatives and a grim prognosis. For this reason, it is of interest to expand the repertoire of available therapies for MCC patients who remain resistant to current primary interventions. Recently, our improved mechanistic understanding of aberrant cell signaling observed in both MCPyV-positive and -negative MCC has facilitated exploration into several small molecules and inhibitors, among them receptor tyrosine kinase inhibitors (TKIs) and somatostatin analogs (SSAs), both of which have positively improved response rates and reduced tumor volumes upon application to treatment of MCC. The introduction of such targeted therapies into treatment protocols holds promise for more personalized care tailored towards patients of diverse subtypes, thereby improving outcomes and mitigating tumor burden, especially for treatment-resistant individuals. In this review, we characterize recent findings surrounding targeted treatments that have been applied to MCC and provide an overview of emerging perspectives on translatable options that can be further developed to offer additional therapeutic avenues for patients with the disease.

Biomaterial-Mediated Genetic Reprogramming of Merkel Cell Carcinoma and Melanoma Leads to Targeted Cancer Cell Killing In Vitro and In Vivo

Tumor immunotherapy is a promising anticancer strategy; however, tumor cells may employ resistance mechanisms, including downregulation of major histocompatibility complex (MHC) molecules to avoid immune recognition. Here, we investigate reprogramming nanoparticles (NPs) that deliver immunostimulatory genes to enhance immunotherapy and address defective antigen presentation in skin cancer in vitro and in vivo. We use a modular poly(beta-amino ester) (PBAE)-based NP to deliver DNA encoding 4-1BBL, IL-12, and IFNγ to reprogram human Merkel cell carcinoma (MCC) cells in vitro and mouse melanoma tumors in vivo to drive adaptive antitumor immune responses. Optimized NP formulations delivering 4-1BBL/IL-12 or 4-1BBL/IL-12/IFNγ DNA successfully transfect MCC and melanoma cells in vitro and in vivo, respectively, resulting in IFNγ-driven upregulation of MHC class I and II molecules on cancer cells. These NPs reprogram the tumor immune microenvironment (TIME) and elicit strong T-cell-driven immune responses, leading to cancer cell killing and T-cell proliferation in vitro and slowing tumor growth and improving survival rates in vivo. Based on expected changes to the tumor immune microenvironment, particularly the importance of IFNγ to the immune response and driving both T-cell function and exhaustion, next-generation NPs codelivering IFNγ were designed. These offered mixed benefits, exchanging improved polyfunctionality for increased T-cell exhaustion and demonstrating higher systemic toxicity in vivo. Further profiling of the immune response with these NPs provides insight into T-cell exhaustion and polyfunctionality induced by different formulations, providing a greater understanding of this immunotherapeutic strategy.

A review of Merkel cell carcinoma

ABSTRACT

Merkel cell carcinoma (MCC) is a rare and aggressive type of metastatic, nonmelanoma skin cancer derived from Merkel cells in the epidermis. MCC can be induced by sun exposure or via Merkel cell polyomavirus (MCV) gene expression. MCV is found in most patients with MCC and is associated with a lower recurrence rate of MCC. MCC has a wide range of clinical presentations that make diagnosis challenging. Histologic examination is performed using unique markers to differentiate it from other diagnoses. This article reviews the pathogenesis, clinical presentation, histopathology, differential diagnosis, and treatment of MCC.

Merkel Cell Carcinoma in an Elderly Male With Extensive Local Disease

Merkel cell carcinoma (MCC) is a rare, highly aggressive neuroendocrine carcinoma of the skin. It is often found in the sun-exposed skin areas of elderly individuals of Caucasian descent. MCC has a tendency for local recurrence and the potential to invade nearby lymph nodes and spread to distant sites in the body. Here, we present the case of an 83-year-old male with a history of multiple comorbidities, including congestive heart failure, obesity, hypertension, benign prostatic hyperplasia, and sarcoidosis, who presented with a slow-growing, fungating lesion on his left lower leg. Histopathological examination revealed MCC with extensive necrosis and involved resection margins. Additional skin lesions on the left knee were confirmed to be MCC. Follow-up CT scans showed lymphadenopathy and a femoral lesion. The patient was deemed a poor candidate for resection and placed on immunotherapy treatment. The low incidence rate and indistinct clinical manifestations of MCC make a conclusive diagnosis dependent on examining histological features and immunohistochemical markers through a lesioned biopsy or resection. Due to the aggressive nature of MCC and the tendency for asymptomatic and painless lesions to escape notice, it is important to raise awareness about this condition. This will lead to earlier detection and intervention, potentially enhancing patient survival rates.

Combined Merkel Cell Carcinoma with Nodal Presentation: Report of a Case Diagnosed with Excisional but Not Incisional Biopsy and Literature Review

Merkel cell carcinoma (MCC) is a rare primary neuroendocrine carcinoma (NEC) of the skin. As compared to pure MCCs, combined MCCs are aggressive and exhibit a higher probability of metastasis. A correct diagnosis might be missed, especially when the biopsy sample is too small or too superficial. We report a 79-year-old Taiwanese male who presented with lymphadenopathy suspicious for lymphoma. A nodal biopsy showed metastatic NEC. A skin tumor in the lower back was identified, and an incisional biopsy showed only squamous cell carcinoma (SCC). A subsequent excisional biopsy was performed based on the advice of the senior pathologist because of the presence of metastatic nodal NEC. Finally, a diagnosis of combined MCC and SCC was confirmed. Our literature review identified 13 cases of combined MCC with nodal metastasis as initial presentations, all with an aggressive clinical course. Both the MCC and non-MCC components could be present in the metastatic nodes. Metastases of pure MCC cells were observed in three combined MCCs in sun-protected areas, probably pointing to a distinct pathogenesis. Excision or punch biopsy to include the deep dermal NEC component is recommended as timely diagnosis is mandatory for appropriate management of patients with this rare skin cancer.

Multimodality imaging findings of infection-induced tumors

Several infections can predispose to certain malignancies in different body parts. These infections include viral, bacterial, and fungal pathogens. Imaging plays a vital role in the diagnosis, staging, and management of these neoplastic conditions. Furthermore, it can help in differentiating infection-related non-neoplastic processes that can mimic malignancies. Both radiologists and clinicians should be familiar with these conditions. This review discusses the epidemiology, pathogenesis, and imaging features of infection-related tumors.

Real-world clinical outcomes with avelumab in patients with Merkel cell carcinoma treated in the USA: a multicenter chart review study

Background

Merkel cell carcinoma (MCC) is a rare, aggressive, cutaneous neuroendocrine neoplasm with annual incidence rates of 0.13–1.6 cases/100,000/year worldwide as of 2018. Chemotherapy for metastatic MCC (mMCC) has high objective response rates (ORRs), but responses are not durable and overall survival (OS) is poor. Avelumab (anti-programmed death-ligand 1) has demonstrated meaningful survival benefit and durable responses in clinical trials for mMCC. This study investigated real-world clinical outcomes in avelumab-treated patients with advanced (stage IIIB/IV) MCC in US academic medical centers.

Methods

We conducted a retrospective chart review of patients with advanced MCC who initiated avelumab between March 1, 2017, and July 31, 2019, at six US academic centers. Data were requested for eligible patients from index date through December 31, 2020. Descriptive analyses were conducted to assess demographic and clinical characteristics, real-world ORR (rwORR), real-world duration of response, real-world progression-free survival (rwPFS), and OS.

Results

Ninety patients with advanced MCC (82%, stage IV; 18%, stage IIIB) received avelumab. Median follow-up was 20.8 months (95% CI: 19.1 to 24.2). Median age was 68 years (range, 48–83), and the majority of patients were men (58%) and white (93%). The primary tumor was most commonly located on the lower limb (38%), with metastases mostly located in lymph nodes (68%), lung (52%), and viscera (52%). Approximately 42% and 26% of patients had an Eastern Cooperative Oncology Group performance status of 2 and 3, respectively. Seventy-three patients (81%) received avelumab as first-line treatment of advanced MCC, while 17 (19%) received avelumab as second-line or later treatment. The median duration of avelumab treatment was 13.5 months (95% CI: 6.4 to 30.6), with 42% of patients still receiving avelumab by the end of follow-up. Patients with avelumab treatment had an rwORR of 73% (95% CI: 64 to 83), median rwPFS of 24.4 months (95% CI: 8.31 to not estimable (NE)), and median OS of 30.7 months (95% CI: 11.2 to NE).

Conclusions

This real-world study of patients with advanced MCC demonstrated that avelumab treatment resulted in a high response rate with durable responses and prolonged survival. The study findings validate the results demonstrated in prospective clinical trials and other observational studies.

Circulating microRNA biomarkers in melanoma and non-melanoma skin cancer

INTRODUCTION

Skin cancer is the most common type of cancer and is classified in melanoma and non-melanoma cancers, which include basal cell, squamous cell and Merkel cell carcinoma. Specific microRNAs are dysregulated in each skin cancer type. MicroRNAs act as oncogene or tumor suppressor gene regulators and are actively released from tumor cells in the circulation. Cell-free microRNAs serve many, and possibly yet unexplored, functional roles, but their presence and abundance in the blood has been investigated as disease biomarker. Indeed, specific microRNAs can be isolated and quantified in the blood, usually in serum or plasma fractions, where they are uncommonly stable. MicroRNA levels reflect underlying conditions and have been associated with skin cancer presence, stage, evolution, or therapy efficacy.

AREAS COVERED

In this review, we summarize the state of the art on circulating microRNAs detectable in skin cancer patients including all the studies that performed microRNA identification and quantification in the circulation using appropriate sample size and statistics and providing detailed methodology, with a specific focus on diagnostic and prognostic biomarkers.

EXPERT OPINION

Circulating microRNAs display a relevant biomarker potential. We expect the development of methodological guidelines and standardized protocols for circulating miRNA quantification in clinical settings.

Is miRNA Regulation the Key to Controlling Non-Melanoma Skin Cancer Evolution?

Non melanoma skin cancer (NMSC) is one of the most common types of skin cancer. It has a number of subtypes, which include basal cell carcinoma, cutaneous squamous cell carcinoma and Merkel cell carcinoma. MicroRNAs are short, non-coding RNA (ribonucleic acid) molecules, capable of regulating gene expression at a post transcriptional level. They play a pivotal role in a variety of physiologic cellular functions and pathologies, including malignant diseases. The development of miRNAs represents an important study field, which has been extensively exploited in melanoma for almost a decade with promising results, therefore we consider it a stepstone for further research projects also in non-melanoma skin cancers. The aim of our study was to explore the current literature in order to present the role of the different miRNAs in some of the most frequent types of NMSC pertaining to oncogenesis, evolution and therapy. The most relevant and accurate available data from the literature were evaluated. Our study concluded that there are almost 100 miRNAs which can be upregulated or downregulated and can play a role in oncogenesis. They can be easily identified in circulation, are stable and they can be important diagnosis/prognosis and therapy monitoring markers.

Clinical Outcomes, Costs, and Healthcare Resource Utilization in Patients with Metastatic Merkel Cell Carcinoma Treated with Immune Checkpoint Inhibitors vs Chemotherapy

Purpose

Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer with poor prognosis. This study compared patient characteristics, comorbidities, adverse events (AEs), treatment persistence, healthcare resource utilization (HRU) and costs in patients with metastatic MCC (mMCC) treated with immune checkpoint inhibitors (ICIs) or recommended chemotherapy per 2018 National Comprehensive Cancer Network (NCCN) Guidelines.

Patients and Methods

A retrospective, observational study was conducted using data from 3/1/2015 through 12/31/2017 from the Premier Healthcare Database, a US hospital discharge database. The study included patients aged ≥12 years with International Classification of Diseases Codes for MCC and metastasis, categorized by their first treatment (index) during the study period (ICI or NCCN-recommended chemotherapy [chemotherapy]). Patient, hospital, and visit characteristics were assessed at the index date and Charlson Comorbidity Index (CCI) score and comorbidities during a 6-month look-back period. Clinical outcomes, including AEs and treatment persistence were assessed over 90 days and HRU and costs over 180 days post-index.

Results

Of 75 patients with mMCC receiving ICIs (n=37) or chemotherapy (n=38), mean age was ≈73 years, and 21.3% had a history of immune-related (IR) conditions. Overall, ICI- and chemotherapy-treated patients were similar in most baseline characteristics, IR comorbidities, and CCI score. However, more ICI patients (46%) than chemotherapy patients (26%) persisted on treatment over 90-day follow-up, odds ratio (95% CI): 2.04 (0.93, 4.47), P=0.07. Over 180-day follow-up, 33% of patients had an inpatient admission with mean length of stay (LOS) ≈2 days shorter for ICI vs chemotherapy (not statistically significant). Total costs, primarily driven by pharmacy costs, were higher for ICIs than chemotherapy; other departmental costs were similar between treatment groups.

Conclusion

In a real-world setting, patients with mMCC receiving ICIs had higher treatment persistence over 90 days, shorter inpatient LOS and similar departmental cost (excluding pharmacy cost) than those receiving chemotherapy.

Surgical Management of Merkel Cell Carcinoma

The incidence of Merkel cell carcinoma (MCC) continues to increase. Understanding of MCC biology has advanced rapidly, with current staging providing valuable prognostic information. MCC treatment often is multidisciplinary. Surgery remains an important component in the staging and treatment, most commonly involving wide excision of the cancer and sentinel lymph node biopsy. Lymphadenectomy is used to treat nodal disease. Radiotherapy enhances locoregional control and possibly survival. Systemic therapies, in particular novel immunotherapies, may be promising in the treatment of advanced or recurrent and metastatic disease.

Avelumab treatment in Italian patients with metastatic Merkel cell carcinoma: experience from an expanded access program

Background

The incidence of Merkel cell carcinoma (MCC), a rare form of skin cancer with a poor prognosis, has increased in Italy in recent decades. Avelumab, an anti-programmed death ligand 1 monoclonal antibody, is approved for the treatment of metastatic MCC (mMCC) based on the results of the phase 2 JAVELIN Merkel 200 trial. The global avelumab expanded access program (EAP) was designed to provide compassionate use of avelumab prior to approval for patients with mMCC who had limited treatment options. We report findings from a subgroup of Italian patients enrolled in the avelumab EAP.

Methods

Eligible patients had mMCC and progressive disease following ≥ 1 prior line of chemotherapy or were ineligible for chemotherapy or clinical trial participation. Patients received avelumab 10 mg/kg intravenously every 2 weeks. Treating physicians were provided with an initial 3-month supply of avelumab; resupply was permitted if the patient achieved a complete response, partial response, stable disease, or other clinical benefit per physician assessment. Safety and efficacy data for the EAP were reported at the treating physician’s discretion.

Results

Between April 1, 2016, and September 14, 2018, 109 requests for avelumab were received from Italy, and 102 were approved. All but 1 of the approved patients had received ≥ 1 prior line of therapy. At data cutoff (March 22, 2019), 95 patients had been supplied with avelumab and response data were available for 55 patients. The objective response rate in response-evaluable patients was 29.1%, including 6 patients (10.9%) who achieved a complete response and 10 patients (18.2%) who achieved a partial response; in the total population supplied with avelumab (n = 95), the proportion who had an objective response was 16.8%. The median duration of treatment in responding patients was 9.7 months (range, 3.5–41.7 months). The most frequently reported treatment-related adverse events were infusion-related reaction (single preferred term; n = 3 [3.2%]) and pyrexia (n = 2 [2.1%]).

Conclusions

Results from Italian patients enrolled in the avelumab EAP are consistent with the findings of the JAVELIN Merkel 200 trial and confirm the efficacy and safety of avelumab treatment in this population.

Anti-EGFR Antibody Plus Chemotherapy Treatment in a Patient with Synchronous Merkel Cell Carcinoma and Colorectal Cancer

Merkel cell carcinoma (MCC) is a rare neuroendocrine cutaneous malignancy. During early stages, surgery is the primary treatment followed by radiotherapy in patients at high risk of recurrence. Definitive radiation therapy is an alternative for patients who are not surgical candidates, reserving chemotherapy for metastatic disease. We present a case of a male patient diagnosed with MCC and stage IV colorectal cancer and we focus on the skin tumor shrinkage after specific colorectal cancer treatment.

Primary Treatment Selection for Clinically Node-Negative Merkel Cell Carcinoma of the Head and Neck

OBJECTIVE

Merkel cell carcinoma practice guidelines recommend sentinel lymph node biopsy after wide local excision for the initial management of clinically node-negative disease without distant metastases (cN0M0). Despite guideline publication, treatment selection remains variable. We hypothesized that receipt of guideline-recommended care would be more common in patients evaluated at academic centers and institutions with high melanoma case volumes and that such therapy would be associated with improved overall survival.

STUDY DESIGN

Retrospective cohort analysis.

SETTING

The National Cancer Database from 2004 to 2015.

METHODS

A total of 3500 patients were included. We utilized Kaplan-Meier analysis and logistic and Cox proportional hazard regressions. Survival analysis was performed on inverse probability-weighted cohorts.

RESULTS

There has been a trend toward evaluation at academic programs at a rate of 1.58% of patients per year (95% CI, 1.06%-2.11%) since 2004. However, the percentage of patients receiving guideline-compliant primary tumor excision and lymph node evaluation has plateaued at approximately 50% since 2012. Guideline-compliant surgical management was more commonly provided to patients evaluated at academic programs than nonacademic programs but only when those institutions had a high melanoma case volume (odds ratio, 2.01; 95% CI, 1.62-2.48). Receipt of guideline-compliant primary tumor excision and lymph node evaluation was associated with improved overall survival (hazard ratio, 0.70; 95% CI, 0.64-0.76).

CONCLUSION

Facility factors affect rates of receipt of guideline-compliant initial surgical management for patients with node-negative Merkel cell carcinoma. Given the survival benefit of such treatment, patients may benefit from care at hospitals with high melanoma case volumes.

Demographic features and changing incidence and presentation of Merkel cell carcinoma in a retrospective single-center case series

Merkel cell carcinoma (MCC) is an uncommon aggressive cutaneous neuroendocrine tumor with high mortality. The purpose of this study is to describe the clinical correlates of MCC and identify changing trends over time using a retrospective chart review of 113 cases in a single tertiary center pathology database from 1997 to 2015. MCC occurred mostly in the elderly (median age 77 years), more often in males (n = 60, 53%), was most commonly located on the head and neck region (n = 63, 56%), and most commonly presented on the left side of the body (n = 59, 52%). Overall, there was an increase in MCC diagnoses per year from 1997 to 2015, with 2.3 times more cases diagnosed in the last 3 years of the study period than in the first 3 years. Furthermore, cases diagnosed after 2008 were more likely to occur in younger patients, less than or equal to 77 years of age (OR 2.32, 95% CI 1.08, 4.97, p = 0.04). The median age of diagnosis among females was 76 years and among males was 74 years. There was no change in the overall age of diagnosis among men and a decrease in age of diagnosis among females during the study. There was an overall increase in the MCC cases diagnosed among women, and a slight increase in the proportion of females affected by MCC throughout the course of the study. This retrospective case series elucidates MCC epidemiologic characteristics and describes how incidence, sex, and age at diagnosis have changed over the course of the study.

Real-world outcomes among US Merkel cell carcinoma patients initiating immune checkpoint inhibitors or chemotherapy

Aim: Retrospectively assessed treatment patterns and clinical and economic outcomes in Merkel cell carcinoma (MCC) patients receiving recommended first-line regimens. Materials & methods: MCC patients newly treated with either immune checkpoint inhibitors (ICIs) or chemotherapies (CTs) were selected from the Veterans Health Administration database (2013-2018); 74 patients (ICIs: 20 and CTs: 54) were selected. Results: Median duration of therapy was 300 days for ICIs and 91 days for CTs. Time to next treatment was 245 and 184 days, respectively. Mean total (per patient per month) costs were $15,306 (ICIs) and $10,957 (CTs), of which 51% and 86%, respectively, were non-MCC therapy-related costs. Conclusion: Despite higher costs, utilization of ICIs in first-line MCC shows clinical advantages over CTs in the real world.

Gene expression profile identifies distinct molecular subtypes and potential therapeutic genes in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare primary cutaneous neoplasm of neuroendocrine carcinoma of the skin. About 80% of the MCC occurs due to Merkel cell polyomavirus (MCPyV) and 20% of the tumors usually occur due to severe UV exposure which is a more aggressive type of MCC. It tends to have an increased incidence rate among elderly and immunosuppressed individuals. On therapeutic level, sub-classification of MCC through molecular subtyping has emerged as a promising technique for MCC prognosis. In current study, two consistent distinct molecular subtypes of MCCs were identified using gene expression profiling data. Subtypes I MCCs were associated with spliceosome, DNA replication and cellular pathways. On the other hand, genes overexpressed in subtype II were found active in TNF signalling pathway and MAPK signalling pathway. We proposed different therapeutic targets based on subtype specificity, such as PTCH1, CDKN2A, AURKA in case of subtype I and MCL1, FGFR2 for subtype II. Such findings may provide fruitful knowledge to understand the intrinsic subtypes of MCCs and the pathways involved in distinct subtype oncogenesis, and will further advance the knowledge in developing a specific therapeutic strategy for these MCC subtypes.

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Merkel cell carcinoma (MCC) a rare and highly aggressive neuroendocrine carcinoma of the skin

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Sub-classification of MCC through molecular subtyping

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Identification of two distinct molecular subtypes of MCCs using gene expression profiling data

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Classification of different therapeutic targets based on subtype specificity

The Role of Anti-PD-1/PD-L1 in the Treatment of Skin Cancer

Skin cancers remain the most common group of cancers globally, and the incidence continues to rise. Although localized skin cancers tend to have excellent outcomes following surgical excisions, the less common cases that become surgically unresectable or metastatic have been associated with poor prognosis and suboptimal treatment responses to cytotoxic chemotherapy. Development of monoclonal antibodies to programmed cell death-1 receptor and its ligand (PD-1/PD-L1) have transformed the management of metastatic melanoma, squamous cell carcinoma, and Merkel cell carcinoma. These agents, as monotherapies, are associated with response rates of approximately 40-60%, many of which persist durably. Further efficacy is observed with combination immunotherapy in advanced melanoma. Early reports suggest similar activity in locally advanced or metastatic basal cell carcinoma. In this review, we describe common molecular features of skin cancers that may render them particularly susceptible to anti-PD-1/PD-L1 and detail results from key clinical trials of these agents across skin cancers. Overall, the superior response rates of skin cancer to anti-PD-1/PD-L1 compared with other solid tumor types are likely due, at least in part, to a high mutational burden and, in Merkel cell carcinoma, viral etiology. Although melanoma has been rigorously studied in the setting of anti-PD-1/PD-L1 treatment, more research is needed for the other skin cancer types to establish toxicity profiles, responses, and quality-of-life outcomes.

Current concepts and approaches to merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive and rare cutaneous cancer of the mechanoreceptor unit of the skin with a neuroendocrine origin. MCC incidence has been on the rise over the past two decades. Risk factors include old age, chronic UV exposure, and immunosuppression. Although MCC is a cutaneous malignancy that is often misdiagnosed as a benign nodule at the time of diagnosis, it has an aggressive disease course due to its high recurrence and metastatic potential. The PD-1/PD-L1 checkpoint blockade has recently shown promising results in the management of advanced MCC. Avelumab and pembrolizumab are considered the new standard of care for metastatic MCC. Despite advances in the field, studies are needed to elucidate the role of immunotherapy for patients who are resistant to treatment. Most ongoing clinical trials aim to assess the efficacy of checkpoint inhibitor combination therapies. This article reviews the most current literature on the surgical and medical management of MCC.

The association between facility volume and overall survival in patients with Merkel cell carcinoma

BACKGROUND

Merkel cell carcinoma is an uncommon malignancy often requiring multidisciplinary management. The purpose of this study was to determine whether high-volume facilities have improved outcomes in patients with Merkel cell carcinoma relative to lower-volume facilities.

METHODS

A total of 5304 patients from the National Cancer Database with stage I-III Merkel cell carcinoma undergoing surgery were analyzed. High-volume facilities were the top 1% by case volume. Multivariable Cox regression and propensity score-matching were performed to account for imbalances between groups.

RESULTS

Treatment at high-volume facilities (hazard ratio: 0.74; 95% confidence interval: 0.65-0.84, P < .001) was independently associated with improved overall survival (OS) in multivariable analyses. In propensity score-matched cohorts, 5-year OS was 62.3% at high-volume facilities vs 56.8% at lower-volume facilities (P < .001). Median OS was 111 months at high-volume facilities vs 79 months at lower-volume facilities.

CONCLUSION

Treatment at high-volume facilities is associated with improved OS in Merkel cell carcinoma. Given the impracticality of referring all elderly patients with Merkel cell carcinoma to a small number of facilities, methods to mitigate this disparity should be explored.

Landscape of current and future therapies of Merkel cell carcinoma

Merkel cell carcinoma is rare and aggressive skin cancer, which occurrence is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus. In recent years, significant progress in understanding the mechanism of Merkel cell carcinoma pathogenesis has been observed. This neoplasm often expresses PD-L1, and MCPyV-specific T cells can express PD-1 thus PD-1/PD-L1 checkpoint therapies seem to be remarkably interesting treatment options. Many clinical trials are currently being conducted to confirm their effectiveness and safety for this group of patients. However, only about half of advanced Merkel cell carcinoma patients could achieve remission or disease stabilization through PD-1/PD-L1 checkpoint therapies thus innovative treatments are still needed. In this article, we have presented current and future directions in the development of Merkel cell carcinoma therapy.

Angiosarcoma in Collision With a Merkel Cell Carcinoma: Case Report and Literature Review

Merkel cell carcinoma (MCC) is a rare entity that most commonly arises from the skin. Angiosarcoma (AS) is a rare malignancy with a predilection for elderly males, has endothelial differentiation and a notoriously poor prognosis despite aggressive therapy. Herein, we report an angiosarcoma colliding with a MCC, in a patient with a past medical history of squamous cell carcinoma, status-post radiation therapy. More specifically, our case represents a collision tumor, a rare entity composed of two histologically distinct neoplasms which coincide together at the same location. This case represents the first documented report of such a presentation. With that being said, its clinical course, prognosis, pathogenesis, and molecular profile, currently remains unclear. Importantly, neoplasms are increasingly being found to be associated with radiation therapy, of which our patient had received. Ultimately, however, with the lack of c-MYC immunohistochemical staining, and a short duration between radiation exposure and presentation, the AS in our case was likely coincidental.

Monoclonal Antibodies in Dermatooncology-State of the Art and Future Perspectives

Monoclonal antibodies (mAbs) targeting specific proteins are currently the most popular form of immunotherapy used in the treatment of cancer and other non-malignant diseases. Since the first approval of anti-CD20 mAb rituximab in 1997 for the treatment of B-cell malignancies, the market is continuously booming and the clinically used mAbs have undergone a remarkable evolution. Novel molecular targets are constantly emerging and the development of genetic engineering have facilitated the introduction of modified mAbs with improved safety and increased capabilities to activate the effector mechanisms of the immune system. Next to their remarkable success in hematooncology, mAbs have also an already established role in the treatment of solid malignancies. The recent development of mAbs targeting the immune checkpoints has opened new avenues for the use of this form of immunotherapy, also in the immune-rich milieu of the skin. In this review we aim at presenting a comprehensive view of mAbs' application in the modern treatment of skin cancer. We present the characteristics and efficacy of mAbs currently used in dermatooncology and summarize the recent clinical trials in the field. We discuss the side effects and strategies for their managing.

Combined radio-immunotherapy leads to complete clinical regression of stage IV Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive neuroendocrine tumour of the skin. While localised disease carries an overall favourable prognosis, metastatic disease is associated with poor clincal outcomes. Most cases of metastatic MCC are managed with systemic chemotherapy or immunotherapy, though 5-year survival for these patients remains a dismal 17%. Here, we present the case of a 79-year-old man with MCC of the right ear with metastases to regional lymph nodes, ipsilateral parotid gland and thoracic spine. He was treated with a combination of first-line radiotherapy and concurrent immune checkpoint inhibition (avelumab), which led to complete clinical regression of disease with minimal adverse effects. This observation suggests that combined radio-immunotherapy warrants larger-scale investigation for use in patients with unresectable MCC.

Cancer-testis antigens as biomarkers for Merkel cell carcinoma: Pitfalls and opportunities

BACKGROUND

The prognosis and treatment options for metastatic Merkel cell carcinoma (MCC) are poor. The immune-privileged status of cancer-testis (CT) antigens imparts tumor specificity, making them ideal candidates for targeted immunotherapy. We investigate the usefulness of the CT antigens SPA17 (sperm protein-17 [SP-17]), IGF2BP3 (insulin-like growth factor-II mRNA-binding protein 3 [IMP-3]), and transmembrane protein with epidermal growth factor (EGF)-like and two follistatin-like domains 1 (TMEFF1) as potential MCC biomarkers and evaluate their possible utility in immunotherapy and molecularly targeted image-guided treatment.

METHODS

The CT antigens SP-17, IMP-3, and TMEFF1 were selected using transcriptome profiling to identify CT antigens expressed in MCC tumors. Antibodies directed against these CT antigens were stained. Twelve normal skin tissue samples were used as a control. The average percentage of positive cells in each tumor was computed.

RESULTS

Twelve of 14 (86%) MCC cases showed crisp nuclear staining for SP-17, with 2.06% of cells staining positive. IMP-3 showed crisp, perinuclear staining in all 14 MCC cases, with 52.93% MCC cells staining positive. TMEFF1 showed perinuclear staining in all 14 MCC cases, with 96.51% of tumor cells staining positive.

CONCLUSIONS

CT antigens were found to be expressed in both MCC and some control tissues. SP-17 was the most specific yet the least sensitive. IMP-3 and TMEFF1 were both sensitive but not specific. CT antigens may represent valuable treatment targets in MCC.

Budget impact model of avelumab in patients with metastatic merkel cell carcinoma in the US

Objective: To estimate the budget impact of avelumab as a treatment option for patients with treatment-naïve first-line (1L) and previously treated second-line or later (2L+) metastatic Merkel cell carcinoma (mMCC) in the US.

Methods: A budget impact model was developed to evaluate the addition of avelumab for the treatment of mMCC patients using a hypothetical 30 million-member US health plan over a 3-year time horizon (2019–2021). The comparator treatments included in the analysis were pembrolizumab and nivolumab (other immuno-oncology agents); and the chemotherapies routinely used in the eligible mMCC population. Model inputs included market share uptake of avelumab and other comparators, duration of treatments, and costs (drugs, health care resource utilization, adverse events). The model was evaluated from a commercial payer perspective. Sensitivity analyses were conducted to test uncertainties arising from the input values used in the model.

Results: In a hypothetical commercial health plan of 30 million members, 285 patients with mMCC were identified over 3 years; 43 patients received avelumab as a 1L treatment over 3 years. In a world without avelumab, the total health care costs of treating patients with mMCC over 3 years were estimated to be US$11,710,115 from a commercial health plan perspective. With avelumab, there were estimated savings of $2,643,173 considering the total costs related to the treatment of mMCC over 3 years (23% reduction in the budget). The incremental cost per member per month over 3 years was −$0.0025.

Conclusion: The model results indicate that the adoption of avelumab as a treatment option for mMCC would likely result in minimal budget impact from a US health plan perspective. Patients with mMCC, a rare condition with a poor prognosis and high unmet need, may benefit greatly from recently approved immunotherapies.

Molecular and immune targets for Merkel cell carcinoma therapy and prevention

Merkel cell carcinoma (MCC) is a rare neuroendocrine carcinoma of the skin, for which the exact mechanisms of carcinogenesis remain unknown. Therapeutic options for this highly aggressive malignancy have historically been limited in both their initial response and response durability. Recent improvements in our understanding of MCC tumor biology have expanded therapeutic options for these patients, namely through the use of immunotherapies such as immune checkpoint inhibitors. Further elucidation of the tumor mutational landscape has identified molecular targets for therapies, which have demonstrated success in other cancer types. In this review, we discuss both current and investigational immune and molecular targets of therapy for MCC.

Recent Therapeutic Advances and Change in Treatment Paradigm of Patients with Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare, aggressive, primary cutaneous neuroendocrine tumor that typically presents as an indurated nodule on sun-exposed areas of the head and neck in the white population. Major risk factors include immunosuppression, UV light exposure, and advanced age. Up to 80% of MCC are associated with Merkel cell polyomavirus. About 50% of patients present with localized disease, and surgical resection with or without adjuvant radiotherapy is generally indicated in this context. However, recurrence rates are high and overall prognosis rather poor, with mortality rates of 33%-46%. MCC is a chemosensitive disease, but responses in the advanced setting are seldom durable and not clearly associated with improved survival. Several recent trials with checkpoint inhibitors (pembrolizumab, avelumab, nivolumab) have shown very promising results with a favorable safety profile, in both chemonaïve and pretreated patients. In 2017, avelumab was approved by several regulatory agencies for the treatment of metastatic MCC, the first drug to be approved for this orphan disease. More recently, pembrolizumab has also been approved by the U.S. Food and Drug Administration in this setting. Immunotherapy has therefore become the new standard of care in advanced MCC. This article reviews current evidence and recommendations for the diagnosis and treatment of MCC and discusses recent therapeutic advances and their implications for care in patients with advanced disease. This consensus statement is the result of a collaboration between the Spanish Cooperative Group for Neuroendocrine Tumors, the Spanish Group of Treatment on Head and Neck Tumors, and the Spanish Melanoma Group. IMPLICATIONS FOR PRACTICE: Merkel cell carcinoma (MCC) is an uncommon aggressive skin cancer associated with advanced age, UV light exposure, and immunosuppression. Up to 80% are associated with Merkel cell polyomavirus. MCC is a chemosensitive disease, but tumor responses in the advanced setting are short-lived with no long-term survivors. Recent clinical trials with immune checkpoint inhibitors (i.e., pembrolizumab, avelumab, nivolumab) have shown promising results, with avelumab becoming the first drug to receive regulatory approval for this orphan indication. Further follow-up is needed, however, to define more adequately the long-term benefits of these drugs, and continued research is warranted to optimize immunotherapeutic strategies in this setting.

Neuroendocrine Key Regulator Gene Expression in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a highly aggressive non-melanoma skin cancer of the elderly which is associated with the Merkel cell polyomavirus (MCPyV). MCC reveals a trilinear differentiation characterized by neuroendocrine, epithelial and pre/pro B-cell lymphocytic gene expression disguising the cellular origin of MCC. Here we investigated the expression of the neuroendocrine key regulators RE1 silencing transcription factor (REST), neurogenic differentiation 1 (NeuroD1) and the Achaete-scute homolog 1 (ASCL1) in MCC. All MCCs were devoid of REST and were positive for NeuroD1 expression. Only one MCC tissue revealed focal ASCL1 expression. This was confirmed in MCPyV-positive MCC cell lines. Of interest, MCPyV-negative cell lines did express REST. The introduction of REST expression in REST-negative, MCPyV-positive MCC cells downregulated the neuroendocrine gene expression. The lack of the neuroendocrine master regulator ASCL1 in almost all tested MCCs points to an important role of the absence of the negative regulator REST towards the MCC neuroendocrine phenotype. This is underlined by the expression of the REST-regulated microRNAs miR-9/9* in REST-negative MCC cell lines. These data might provide the basis for the understanding of neuroendocrine gene expression profile which is expected to help to elucidate the cellular origin of MCC.

Recurrent Merkel cell carcinoma of the gluteal region: A case report

Merkel cell carcinoma (MCC) is a rare malignant tumor of the skin. The development of MCC on non-sun-exposed skin is extremely rare, with few cases reported in the literature. The present authors aimed to highlight the characteristic features and treatment options of this tumor. The present authors present a 50-year-old man who developed MCC on the left gluteal region (non-sun-exposed skin). After surgery with clear margins, adjuvant radiotherapy was given. Three months after radiotherapy, lymphatic recurrence was observed and he was treated with chemotherapy. On follow-up, systemic metastases were found and palliative treatment was planned.

Strategies for immune evasion by human tumor viruses

Immune evasion is a hallmark of viral persistence. For the seven human tumor viruses to establish lifelong infection in their hosts, they must successfully control the host response to them. Viral inhibition of immune responses occurs at many levels. While some viruses directly target the pattern recognition receptors (PRR) of the innate immune system, they may also antagonize downstream effectors of PRR signaling cascades or activation of transcription, which would otherwise induce a type I interferon (IFN) and/or pro-inflammatory cytokine response. Secretion of IFN activates the type I interferon receptor (IFNAR) signaling pathway, which is also prone to viral inhibition. To evade the adaptive host response, viruses also target various mechanisms including antigen processing and presentation.

Phosphatidylinositol 3-kinase p110δ expression in Merkel cell carcinoma

The prognosis of stage III/IV Merkel cell carcinoma (MCC) is very poor. The Phosphatidylinositol 3-kinase p110δ specific inhibitor idelalisib has recently been reported to induce complete clinical remission in a stage IV MCC patient. Here we assessed the expression of p110δ in primary MCC and MCC cell lines including its functionality. Immunofluorescence microscopy revealed a specific cytoplasmic p110δ expression in 71.4% of the tested MCCs and in all tested MCC cell lines. Compared to the B cell leukemia cell line REH all MCC cell lines, except MKL-1, revealed a lower response towards the treatment with idelalisib. MKL-1 showed a 10-fold higher IC₅₀ compared to REH which was accompanied by a significant decrease of Akt phosphorylation. However, treating the MCC cells with the specific PI3K p110α subunit inhibitor BYL719 led to a more effective decrease of the cell viability compared to idelalisib: WaGa cells 30-fold, PeTa cells 15-fold and all other MCC cell lines 3-fold. Although PI3K p110δ is expressed in the majority of MCCs and cell lines its inhibition by idelalisib alone does not suffice to effectively affect MCC cells viability.

Identifying an Optimal Adjuvant Radiotherapy Dose for Extremity and Trunk Merkel Cell Carcinoma Following Resection: An Analysis of the National Cancer Database

Importance

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine neoplasm with a high risk of recurrence following resection. Despite a rising incidence over the past 3 decades, there is a paucity of prospective data owing to the rarity of this disease.

Objective

To determine the optimal adjuvant radiation therapy (RT) dose following resection of localized MCC of the extremities or trunk.

Design, Setting, and Participants

Using the National Cancer Database, a large national database consisting of a heterogeneous population and treatment settings, we retrospectively analyzed a cohort of 2093 patients 18 years or older with stage I to III MCC of the extremities and/or trunk treated with definitive surgery and adjuvant RT between 1998 and 2011. Exclusion criteria included receiving treatment with palliative intent, preoperative RT, non-external-beam RT, and radiation dose of 30 Gy or lower or 70 Gy or higher. Cox proportional hazards regression model was used to compare overall survival (OS) between RT dose groups, accounting for age, sex, race, stage, surgery type, margin status, comorbidities, and use of chemotherapy.

Exposures

Radiation therapy dose was categorized into 4 groups: group 1 received the lowest dose (>30 to <40 Gy); group 2, the next lowest (40 to <50 Gy); group 3, the second highest dose (50 to 55 Gy); and group 4, the highest dose (>55 to 70 Gy).

Main Outcome and Measure

Overall survival.

Results

Data from 2093 patients were analyzed; there were 1293 men (61.8%) and 800 women (38.2%) (median age, 73 years). After a median follow-up of 37 months for the entire cohort, 904 deaths were reported. The 3-year OS rates for groups 1, 2, 3, and 4 were 41.8%, 69%, 69.2%, and 66%, respectively (omnibus P < .001). Compared with group 3 (50 to 55 Gy), equivalent OS was seen in group 2 (40 to <50 Gy; adjusted hazard ratio [AHR], 0.89; 95% CI, 0.63-1.27; P = .52) and group 4 (>55 to 70 Gy; AHR, 1.18; 95% CI, 0.93-1.48; P = .17), but worse OS was found in group 1 (>30 to <40 Gy; AHR, 2.63; 95% CI, 1.44-4.80; P < .001).

Conclusions and Relevance

Adjuvant RT dose from 40 to lower than 50 Gy appears adequate for extremities and/or trunk stage I to III MCC, with OS equivalent to that found at higher-dose regimens (>50 to 70 Gy).

Understanding the influence of patient demographics on disease severity, treatment strategy, and survival outcomes in merkel cell carcinoma: a surveillance, epidemiology, and end-results study

Objective

To identify trends in patient presentation and outcomes data that may guide the development of clinical algorithms on Merkel Cell Carcinoma (MCC).

Methods

We performed a retrospective cohort study searching in the National Cancer Institute's SEER registry for documented MCC cases from 1986-2013. No exclusion criteria were applied. We hereby identified 7,831 original MCC entries. Demographics, staging, and socioeconomic characteristics were identified and treatment modality likelihoods and survival data were calculated via logistic regression and Kaplan-Meier statistical modeling.

Results

Concerning tumor localization, 44.5% (n= 3,485) were located on the head and neck, and 47.8% were located on the trunk and extremities (n= 3,742). Male and younger patients are more likely to receive radiation than surgery with no differences seen among patient race. Caucasians and “Other” races both showed higher overall survival than African American patients. States with higher median household income levels demonstrated survival advantage. Income quartiles yielded no differences in surgical or radiotherapy interventions. Moreover, patients who forego radiotherapy had a poorer overall survival.

Limitations

Generalizability of SEER data, potential intrinsic coding inconsistencies, and limited information on patient comorbidities, sentinel lymph node and surgical margin status are major limitations. There is no information regarding medical intervention such as systemic chemotherapy or immunotherapy. Recoding efforts are inconclusive regarding variables such as tumor infiltrating lymphocytes, mutations, or immunosuppression status, which are well-documented for other cancers within the database.

Conclusion

MCC lesions of the head and neck region, lower income quartiles, and African American race are associated with higher mortality. MCC patients have a median household income that is significantly higher than national values with no significant difference in subsequent treatment modalities (surgery or radiotherapy) based on socioeconomic markers. A lack of radiotherapy is associated with higher mortality.

The Exceptional Oncogenicity of HTLV-1

Human T-cell leukemia virus-1 (HTLV-1) is the first pathogenic human retrovirus identified in 1979 by the Gallo group. HTLV-1 causes fatal T-cell leukemia (adult T cell leukemia) and a progressive myelopahy (HTLV-1-associated myelopathy/ tropical spastic paraparesis, HAM/TSP) and other disorders. Since the discovery of HTLV-1, several other microorganisms are demonstrated to cause cancer in humans. In this article, we investigated the oncogenic capacity of HTLV-1, in comparison with those of other oncoviruses and one oncobacterium (Helicobacter pylori, H. Pylori) based on published literature. We conclude here that HTLV-1 is one of the most and may be the most carcinogenic among them and arguably one of the most potent of the known human carcinogens. This fact has not been noted before and is particularly important to justify why we need to study HTLV-1 as an important model of human viral oncogenesis.

Merkel Cell Carcinoma of the Head and Neck: Recommendations for Diagnostics and Treatment

Background

Merkel cell carcinoma (MCC) is a rare, aggressive tumor that often occurs in the head and neck region. Because of these features, the classifications and diagnostic and treatment regimens are frequently modified. Especially in the anatomically complex head and neck region, it is crucial to be aware of the current recommendations for diagnostics and treatment of MCC to ensure appropriate treatment. This overview aims to summarize the currently available literature.

Methods

The authors reviewed the relevant literature and international guidelines for MCC from 2012 to 2017 with respect to epidemiology and prognosis, diagnostic procedures and imaging, surgery, radiation, systemic treatment, and aftercare. These results were compared with existing guidelines, some of them current, and recommendations were derived.

Results

Marked developments in imaging have resulted in an increased use of functional imaging. The surgical concepts have changed regarding safety margins and the use of sentinel node biopsies. In systemic treatment, a move from conventional agents toward immuno-oncology can be observed.

Conclusions

For staging, it is important to be as exact as possible using functional imaging (e.g., positron emission tomography/computed tomography scan), especially in the head and neck area with its complex lymph drainage. This often plays an especially important role in early stages of the tumor, when the resection margin can be reduced to preserve the organ. Aftercare also should include functional imaging. In an advanced, metastatic stage, immuno-oncology (PD-1, PD-L1, CTLA-4) is superior to the previous methods of systemic treatment.

Histological Features, p53, c-Kit, and Poliomavirus Status and Impact on Survival in Merkel Cell Carcinoma Patients

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive malignancy from neuroendocrine cells in the skin. Despite being one of the most life-threatening of skin cancers, little is known about the potential signaling mechanism that drives carcinogenesis in MCC. The purpose of this study is to assess the impact of Merkel cell polyomavirus (MCPyV), p53, and c-kit on the histological features and clinical prognosis of MCC treated in our regional hospitals.

METHOD

The design was a retrospective study. The specimens were taken between 1993 and 2013 in 2 referral hospitals of Southern Spain. Data were collected retrospectively and analyzed using SPSS software.

RESULTS

Thirteen lesions from 13 subjects were included in the study. Positivity for c-kit was associated with the absence of MCPyV viral DNA (P = 0.048) and positivity for p53 (P = 0.002). More rate of mitoses per high-power field was presented significantly in those specimens with: positivity for c-kit (P = 0.046), positivity for p53 (P = 0.05), lesions with infiltrative growth pattern (P = 0.008), and lymphovascular invasion (P = 0.034). We observed an inverse relationship between p53 expression and MCPyV infection (Pearson's coefficient: -0.524; P = 0.046) and between c-kit expression and MCPyV infection (Pearson's coefficient: -0.548; P = 0.05), whereas the relationship was positive between p53 expression and c-kit expression (Pearson's coefficient: 0.884; P < 0.001).

CONCLUSION

We conclude that presence of MCPyV DNA has no effect on overall survival. MCCs with p53 and c-kit expressions are associated with the absence of or low MCPyV DNA showing an inverse relationship. A multifactorial molecular pathogenesis where positivity for p53 and c-kit are associated with other mechanisms different than MCPyV (such as pro-mitotic factors) may lead to aggressive clinical behavior.

Shared Oncogenic Pathways Implicated in Both Virus-Positive and UV-Induced Merkel Cell Carcinomas

Merkel cell carcinoma (MCC) is a highly malignant neuroendocrine tumor of the skin whose molecular pathogenesis is not completely understood, despite the role that Merkel cell polyomavirus can play in 55-90% of cases. To study potential mechanisms driving this disease in clinically characterized cases, we searched for somatic mutations using whole-exome sequencing, and extrapolated our findings to study functional biomarkers reporting on the activity of the mutated pathways. Confirming previous results, Merkel cell polyomavirus-negative tumors had higher mutational loads with UV signatures and more frequent mutations in TP53 and RB compared with their Merkel cell polyomavirus-positive counterparts. Despite important genetic differences, the two Merkel cell carcinoma etiologies both exhibited nuclear accumulation of oncogenic transcription factors such as NFAT or nuclear factor of activated T cells (NFAT), P-CREB, and P-STAT3, indicating commonly deregulated pathogenic mechanisms with the potential to serve as targets for therapy. A multivariable analysis identified phosphorylated CRE-binding protein as an independent survival factor with respect to clinical variables and Merkel cell polyomavirus status in our cohort of Merkel cell carcinoma patients.

Dual mTOR inhibitor MLN0128 suppresses Merkel cell carcinoma (MCC) xenograft tumor growth

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin cancer. Pathologic activation of PI3K/mTOR pathway and elevated expression of c-Myc are frequently detected in MCC. Yet, there is no targeted therapy presently available for this lethal disease. Recently, MLN0128, a second-generation dual TORC1/2 inhibitor is shown to have therapeutic efficacy in preclinical studies. MLN0128 is currently in clinical trials as a potential therapy for advanced cancers. Here we characterize the therapeutic efficacy of MLN0128 in the preclinical setting of MCC and delineate downstream targets of mTORC1/2 in MCC cellular systems. MLN0128 significantly attenuates xenograft MCC tumor growth independent of Merkel cell polyomavirus. Moreover, MLN0128 markedly diminishes MCC cell proliferation and induces apoptosis. Further investigations indicate that senescence does not contribute to MLN0128-mediated repression of xenograft MCC tumor growth. Finally, we also observe robust antitumor effects of MLN0128 when administered as a dual therapy with JQ1, a bromodomain protein BRD4 inhibitor. These results suggest dual blockade of PI3K/mTOR pathway and c-Myc axis is effective in the control of MCC tumor growth. Our results demonstrate that MLN0128 is potent as monotherapy or as a member of combination therapy with JQ1 for advanced MCC.

Merkel cell carcinoma: Epidemiology, prognosis, therapy and unmet medical needs

Merkel cell carcinoma (MCC) is a rare skin cancer that is associated with Merkel cell polyomavirus infection in most cases. Incidence rates of MCC have increased in past decades. Risk factors for MCC include ultraviolet light exposure, immunosuppression and advanced age. MCC is an aggressive malignancy with frequent recurrences and a high mortality rate, although patient outcomes are generally more favourable if the patient is referred for treatment at an early stage. Although advances have been made recently in the MCC field, large gaps remain with regard to definitive biomarkers and prognostic indicators. Although MCC is chemosensitive, responses in advanced stages are mostly of short duration, and the associated clinical benefit on overall survival is unclear. Recent nonrandomised phase 2 clinical trials with anti-PD-L1/PD-1 antibodies have demonstrated safety and efficacy; however, there are still no approved treatments for patients with metastatic MCC. Patients with advanced disease are encouraged to participate in clinical trials for treatment, indicating the largely unmet need for durable, safe treatment within this population.

The use of dermatoscopy in diagnosis and therapy of nonmelanocytic skin cancer

Today, dermatoscopy is an integral part of every clinical skin examination, as it markedly enhances the early detection of melanocytic and nonmelanocytic skin cancer (NMSC) compared to naked-eye inspection. Besides its diagnostic use, this noninvasive method is increasingly important in the selection of as well as the response assessment to various therapies used for NMSC, including basal cell carcinoma, actinic keratoses, squamous cell carcinoma, and also rare tumors such as Merkel cell carcinoma, angiosarcoma, or dermatofibrosarcoma protuberans. Thus, dermatoscopy is a valid tool for the preoperative assessment of tumor margins in basal cell carcinoma, but also for follow-up of actinic keratoses after topical treatment. The present article presents an overview on the use of dermatoscopy in the diagnosis and therapy of various types of NMSC.

Merkel cell polyomavirus, a highly prevalent virus with tumorigenic potential

Merkel cell polyomavirus (MCPyV) is the only human polyomavirus known to be involved in tumorigenesis. Like other human polyomaviruses, MCPyV is highly prevalent in the healthy population, yet the MCPyV-associated Merkel cell carcinoma (MCC) is a very rare disease. Although in vitro and in vivo models have provided significant details regarding molecular functions of viral oncoproteins during cellular transformation, many open questions about the natural life cycle of the virus, its mechanisms of persistence and the precise role of MCPyV during MCC pathogenesis remain. This review will carve out the specifics of MCPyV biology and discuss unresolved issues to help the reader gain a better understanding of what may differentiate MCPyV from other polyomaviruses.