Merkel cell carcinoma: correlation of KIT expression with survival and evaluation of KIT gene mutational status

Current status of Merkel cell carcinoma: Epidemiology, pathogenesis and prognostic factors

Merkel cell carcinoma (MCC) is an extremely rare cutaneous neuroendocrine cancer, with an incidence approximately 40 times lower than that of malignant melanoma; however, its significantly inferior survival rate compared to melanoma establishes MCC as the most lethal form of skin cancer. In recent years, a substantial body of literature has demonstrated a gradual increase in the incidence of MCC. Although the two factors that contribute to MCC, ultraviolet radiation and Merkel cell polyomavirus infection, have been well established, the specific pathogenesis of this disease remains unclear. Additionally, considering the high lethality and recurrence rates of MCC, as well as the absence of specific antitumor drugs, it is crucial to elucidate the factors that can accurately predict patients' outcomes. In this review, we summarized the significant advancements in the epidemiological characteristics, pathogenesis, and the factors that influence patient prognosis of MCC to enhance clinical practices and public health efforts.

MicroRNA dysregulations in Merkel cell carcinoma: Molecular mechanisms and clinical applications

Merkel cell carcinoma (MCC) is an aggressive skin malignancy with two distinct etiologies. The first, which accounts for the highest proportion, is caused by Merkel cell polyomavirus (MCPyV), a DNA tumor virus. A second, UV-induced, MCC form has also been identified. Few MCC diagnostic, prognostic, and therapeutic options are available. MicroRNAs (miRNAs) are small noncoding RNA molecules, which play a key role in regulating various physiologic cellular functions including cell cycling, proliferation, differentiation, and apoptosis. Numerous miRNAs are dysregulated in cancer, by acting as either tumor suppressors or oncomiRs. The aim of this review is to collect, summarize, and discuss recent findings on miRNAs whose dysregulation has been assumed to play a role in MCC. The potential clinical application of miRNAs as diagnostic and prognostic biomarkers in MCC is also described. In the future, miRNAs will potentially gain clinical significance for the improvement of MCC diagnostic, prognostic, and therapeutic options.

Intron 4-5 hTERT DNA Hypermethylation in Merkel Cell Carcinoma: Frequency, Association with Other Clinico-pathological Features and Prognostic Relevance

Merkel cell carcinoma (MCC) is an aggressive skin tumor with neuroendocrine differentiation, mainly affecting elderly population or immunocompromised individuals. As methylation of the human telomerase reverse transcriptase (mhTERT) has been shown to be a prognostic factor in different tumors, we investigated its role in MCC, in particular in intron 4-5 where rs10069690 has been mapped and recognized as a cancer susceptibility locus. DNA methylation analysis of hTERT gene was assessed retrospectively in a cohort of 69 MCC patients from the University of Bologna, University of Turin and University of Insubria. Overall mortality was evaluated with Kaplan-Meier curves and multivariable Royston-Parmar models. High levels of mhTERT (mhTERT_high) (HR = 2.500, p = 0.015) and p63 (HR = 2.659, p = 0.016) were the only two clinico-pathological features significantly associated with a higher overall mortality at the multivariate analysis. We did not find different levels of mhTERT between MCPyV (+) and (-) cases (21 vs 14, p = 0.554); furthermore, mhTERT_high was strongly associated with older age (80.5 vs 72 years, p = 0.026), no angioinvasion (40.7% vs 71.0%, p = 0.015), lower Ki67 (50 vs 70%, p = 0.005), and PD-L1 expressions in both tumor (0 vs 3%, p = 0.021) and immune cells (0 vs 10%, p = 0.002). mhTERT is a frequently involved epigenetic mechanism and a relevant prognostic factor in MCC. In addition, it belongs to the shared oncogenic pathways of MCC (MCPyV and UV-radiations) and it could be crucial, together with other epigenetic and genetic mechanisms as gene amplification, in determining the final levels of hTERT mRNA and telomerase activity in these patients.

Merkel Cell Carcinoma from Molecular Pathology to Novel Therapies

Merkel cell carcinoma (MCC) is an uncommon and highly aggressive skin cancer. It develops mostly within chronically sun-exposed areas of the skin. MCPyV is detected in 60-80% of MCC cases as integrated within the genome and is considered a major risk factor for MCC. Viral negative MCCs have a high mutation burden with a UV damage signature. Aberrations occur in RB1, TP53, and NOTCH genes as well as in the PI3K-AKT-mTOR pathway. MCC is highly immunogenic, but MCC cells are known to evade the host's immune response. Despite the characteristic immunohistological profile of MCC, the diagnosis is challenging, and it should be confirmed by an experienced pathologist. Sentinel lymph node biopsy is considered the most reliable staging tool to identify subclinical nodal disease. Subclinical node metastases are present in about 30-50% of patients with primary MCC. The basis of MCC treatment is surgical excision. MCC is highly radiosensitive. It becomes chemoresistant within a few months. MCC is prone to recurrence. The outcomes in patients with metastatic disease are poor, with a historical 5-year survival of 13.5%. The median progression-free survival is 3-5 months, and the median overall survival is ten months. Currently, immunotherapy has become a standard of care first-line therapy for advanced MCC.

Virus-positive Merkel Cell Carcinoma Is an Independent Prognostic Group with Distinct Predictive Biomarkers

PURPOSE

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma that can be divided into two classes: virus-positive (VP) MCC, associated with oncogenic Merkel cell polyomavirus (MCPyV); and virus-negative (VN) MCC, associated with photodamage.

EXPERIMENTAL DESIGN

We classified 346 MCC tumors from 300 patients for MCPyV using a combination of IHC, ISH, and qPCR assays. In a subset of tumors, we profiled mutation status and expression of cancer-relevant genes. MCPyV and molecular profiling results were correlated with disease-specific outcomes. Potential prognostic biomarkers were further validated by IHC.

RESULTS

A total of 177 tumors were classified as VP-MCC, 151 tumors were VN-MCC, and 17 tumors were indeterminate. MCPyV positivity in primary tumors was associated with longer disease-specific and recurrence-free survival in univariate analysis, and in multivariate analysis incorporating age, sex, immune status, and stage at presentation. Prioritized oncogene or tumor suppressor mutations were frequent in VN-MCC but rare in VP-MCC. TP53 mutation developed with recurrence in one VP-MCC case. Importantly, for the first time we find that VP-MCC and VN-MCC display distinct sets of prognostic molecular biomarkers. For VP-MCC, shorter survival was associated with decreased expression of immune markers including granzyme and IDO1. For VN-MCC, shorter survival correlated with high expression of several genes including UBE2C.

CONCLUSIONS

MCPyV status is an independent prognostic factor for MCC. Features of the tumor genome, transcriptome, and microenvironment may modify prognosis in a manner specific to viral status. MCPyV status has clinicopathologic significance and allows for identification of additional prognostic subgroups.

Molecular Profiling of Merkel Cell Polyomavirus-Associated Merkel Cell Carcinoma and Cutaneous Melanoma

Merkel cell carcinoma (MCC) is a rare, high-grade, aggressive cutaneous neuroendocrine malignancy most commonly associated with sun-exposed areas of older individuals. A relatively newly identified human virus, the Merkel cell polyomavirus (MCPyV) has been implicated in the pathogenesis of MCC. Our study aimed to examine nine MCC cases and randomly selected 60 melanoma cases to identify MCPyV status and to elucidate genetic differences between virus-positive and -negative cases. Altogether, seven MCPyV-positive MCC samples and four melanoma samples were analyzed. In MCPyV-positive MCC RB1, TP53, FBXW7, CTNNB1, and HNF1A pathogenic variants were identified, while in virus-negative cases only benign variants were found. In MCPyV-positive melanoma cases, besides BRAF mutations the following genes were also affected: PIK3CA, STK11, CDKN2A, SMAD4, and APC. In contrast to studies found in the literature, a higher tumor burden was detected in virus-associated MCC compared to MCPyV-negative cases. No association was identified between virus infection and tumor burden in melanoma samples. We concluded that analyzing the key morphologic and immunohistological features of MCC is critical to avoid confusion with other cutaneous malignancies. Molecular genetic investigations such as next-generation sequencing (NGS) enable molecular stratification, which may have future clinical impact.

Feline and canine Merkel cell carcinoma: A case series and discussion on cellular origin

Merkel cell carcinoma (MCC) is in humans and cats a malignant cutaneous neuroendocrine carcinoma, whereas in dogs it possibly has a more benign behaviour. It may be cytologically confused with round cell tumours such as lymphoma because of its striking cytomorphologic similarity. Although MCC is considered to arise from Merkel cells, recent findings indicated that primitive (epi‐)dermal stem cells, early B‐cells or dermal fibroblasts were the origin of human MCC. The aim of our study was to evaluate a possible lymphoid origin in feline and canine MCCs. Specific analysis of CD3, PAX‐5, KIT and PARR assay were performed in 3 feline and 3 canine MCCs. All MCCs (6/6) were negative for CD3 and PAX‐5. KIT was expressed in all MCCs (6/6). Assessment of clonality by PARR assay exhibited a polyclonal B‐ and T‐cell receptor rearrangement in all five cases tested. In conclusion, a lymphoid origin of feline and canine MCCs could not be demonstrated. This is in contrast with human MCCs, that often express early B‐cell lineage markers.

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.

TdT Expression Is a Marker of Better Survival in Merkel Cell Carcinoma, and Expression of B-Cell Markers Is Associated With Merkel Cell Polyomavirus

OBJECTIVES

Merkel cell carcinoma is a rare but very aggressive cutaneous tumor. We evaluated the prognostic potential of B-cell markers (terminal deoxynucleotidyl transferase [TdT], PAX5, CD117), follicular stem cell markers (CK15, CK19), p63, p53, RB, and Merkel cell polyomavirus (MCPyV; CM2B4) in 136 primary cutaneous Merkel cell carcinomas.

METHODS

Clinical, histopathologic, and immunohistochemical analyses were performed. The results were correlated with patient outcomes by Fisher exact test, log-rank tests, and Cox multivariate models.

RESULTS

By Fisher exact test, although TdT significantly correlated with both lack of progression (P = .0087) and alive status (P = .0056), MCPyV status correlated only with alive status (P = .031). In univariate analyses, TdT, MCPyV, and RB significantly correlated with improved overall survival, whereas p63 and CK15 correlated with worse overall survival. However, in multivariate analyses, only TdT expression remained as an independent predictor of improved overall survival, Merkel cell carcinoma-specific survival, and progression-free survival. By linear regression analyses, significant correlations between MCPyV vs TdT, PAX5, and CD117 were observed.

CONCLUSIONS

TdT expression is a potential marker of better survival in Merkel cell carcinoma. Expression of B-cell markers is associated with MCPyV, suggesting that clonal viral integration might play a role in the expression of these markers.

Danger is only skin deep: aggressive epidermal carcinomas. An overview of the diagnosis, demographics, molecular-genetics, staging, prognostic biomarkers, and therapeutic advances in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a high grade primary cutaneous neuroendocrine carcinoma and is among the most aggressive cutaneous malignancies. The rising incidence of MCC, together with its often rapidly aggressive course, underscore a critical need to recognize the histopathologic and the immunohistochemical features that inform its accurate diagnosis. In the current review, we summarize the current state of knowledge regarding the accurate diagnosis of MCC and the exclusion of other entities in the differential diagnosis. We provide a comprehensive review of genomic studies that identified the molecular-genetic drivers of MCC as well as a summary of studies identifying prognostic biomarkers that can facilitate risk stratification. Importantly, Merkel cell polyomavirus (MCPyV) appears to be causative in most cases of MCC and represents both a diagnostic and prognostic marker. Finally, as staging of MCC has undergone critical refinements with the introduction of the 8th Edition of the American Joint Committee on Cancer staging system, we provide an update on MCC staging. In particular, the prognostic significance of the sentinel lymph node (SLN) in MCC necessitates a systematic approach to its evaluation and diagnosis to ensure accurate and consistent risk stratification for patients, and we therefore provide a comprehensive overview of SLN evaluation in MCC. Finally, the intimate relationship between MCC and the integrity of the host immune system has led to paradigm-shifting therapeutic advances with the successful application of immune checkpoint blockade to treat patients with advanced disease, and we therefore summarize those studies and the correlative studies in which predictive biomarkers have been identified.

The biology and treatment of Merkel cell carcinoma: current understanding and research priorities

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer associated with advanced age and immunosuppression. Over the past decade, an association has been discovered between MCC and either integration of the Merkel cell polyomavirus, which likely drives tumorigenesis, or somatic mutations owing to ultraviolet-induced DNA damage. Both virus-positive and virus-negative MCCs are immunogenic, and inhibition of the programmed cell death protein 1 (PD-1)–programmed cell death 1 ligand 1 (PD-L1) immune checkpoint has proved to be highly effective in treating patients with metastatic MCC; however, not all patients have a durable response to immunotherapy. Despite these rapid advances in the understanding and management of patients with MCC, many basic, translational and clinical research questions remain unanswered. In March 2018, an International Workshop on Merkel Cell Carcinoma Research was held at the US National Cancer Institute, at which academic, government and industry experts met to identify the highest-priority research questions. Here, we review the biology and treatment of MCC and report the consensus-based recommendations agreed upon during the workshop.

Merkel cell carcinoma (MCC) is a rare and aggressive form of nonmelanoma skin cancer. The availability of immune checkpoint inhibition has improved the outcomes of a subset of patients with MCC, although many unmet needs continue to exist. In this Consensus Statement, the authors summarize developments in our understanding of MCC while also providing consensus recommendations for future research.

Treatment patterns, comorbidities, healthcare resource use, and associated costs by line of chemotherapy and level of comorbidity in patients with newly-diagnosed Merkel cell carcinoma in the United States

AIMS

To examine the characteristics of patients with newly-diagnosed Merkel cell carcinoma (MCC), analyze their treatment patterns and comorbidities after diagnosis, and evaluate the economic burden on the MCC patient population in the US.

MATERIALS AND METHODS

This observational, non-interventional cohort study identified patients with MCC that were newly-diagnosed between January 1, 2010 through December 31, 2014, and whose data were either in the MarketScan Commercial Claims and Encounters (CCAE) or Medicare Supplemental and Coordination of Benefits databases. Standard descriptive statistics were used to describe patient demographics, clinical characteristics, treatment regimens, and healthcare resource use (HRU) and cost.

RESULTS

Following MCC diagnosis, most patients in the study population (n = 2,177) received only surgery (34.5%) or surgery and radiotherapy without chemotherapy (22.0%), while 14.5% of patients received none of these treatments; 27.5% of patients received at least one line of chemotherapy as part of their treatment. Mean total healthcare costs per patient per year (PPPY), as well as mean inpatient, outpatient, and pharmacy costs, were significantly greater for patients who received chemotherapy compared with those who received other or no treatments. Higher HRU and mean costs were associated with increasing patient comorbidity burden, ranging from $62,401 PPPY in Deyo Charlson Comorbidity Index level 1 to $109,690 in level ≥3.

LIMITATIONS

The study used claims databases that were limited to patients who are covered by large employer-sponsored insurance and/or Medicare and did not provide information regarding the rationale for treatment choice or resource use.

CONCLUSIONS

The choice of treatment is a major factor in determining healthcare costs associated with MCC, with the highest costs in patients receiving chemotherapy. Patients with MCC often exhibit comorbidities, and both HRU and healthcare costs increase significantly with each comorbidity level.

Update on Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma. Incidence of MCC continues to rise, and risk factors include advanced age, pale skin, chronic sun exposure, and immune suppression. Diagnosing MCC utilizes a combination of morphology and immunohistochemistry. Merkel cell polyomavirus (MCPyV) is present in approximately 70-80% of MCCs and represents a key pathogenic driver in those MCCs. In contrast, MCPyV-negative MCCs arise through progressive accumulation of ultraviolet-light induced somatic mutations. Staging of MCC proceeds according to the American Joint Commission on Cancer (AJCC) 8th Edition, which utilizes features of the primary tumor together with regional lymph node(s) (clinically and/or pathologically detected) and/or distant metastases. Many potentially useful biomarkers have been studied to refine risk stratification in MCC. In recent years, the host immune infiltrate has been leveraged as immune checkpoint blockade has emerged as an efficacious mode of treatment for patients with advanced MCC.

EUS-FNA of the Merkel cell carcinoma metastasis to the pancreas: Cytomorphology and immunocytochemistry on direct cytological smears

OBJECTIVE

To report two cases of Merkel cell carcinoma (MCC) metastatic to the pancreas diagnosed with endoscopic ultrasound-guided-fine needle aspiration (EUS-FNA) and to add the case of concomitant chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) and MCC to the literature. The aim is to alert the cytopathologists once more to the problems of differential diagnosis of pancreatic metastasis of MCC and to describe the possibilities of ancillary methods performed on direct cytological smears.

METHODS

EUS-FNA procedures were performed according to standard institution protocol, using 22-G needles with cytopathologist on-site. Based on rapid on-site evaluation (ROSE), additional passes were made for immunocytochemistry (ICC). A mini panel of antibodies was used to aid the differential diagnosis.

RESULTS

Smears revealed a dispersed pattern of small round cells with scant cytoplasm, round nuclei with inconspicuous nucleoli and occasional nuclear moulding, suspicious of small cell carcinoma. Results of ICC applied to the direct cytological smears were as follows: LCA negative, Cytokeratin (clone MNF116) positive, TTF-1 negative, CD 56 positive, NSE weakly positive, Chromogranin A weakly positive and CK20 positive, in one case in a dot-like perinuclear pattern. The diagnosis of MCC was made.

CONCLUSION

Increasing incidence of MCC warrants the inclusion of MCC in the differential diagnosis of tumours of small round blue cell morphology even in unusual sites. The cytomorphological features coupled with an ICC panel are usually enough to make a confident diagnosis of MCC. EUS-FNA is a minimally invasive technique which enables sampling adequate tissue for all the ancillary methods eventually needed to support the diagnosis.

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.

Molecular characteristics and potential therapeutic targets in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine skin tumour occurring preferentially in elderly and immunosuppressed individuals. Multiple studies have provided insight into the molecular alterations of MCC, leading to the design of several ongoing clinical trials testing chemotherapy, targeted therapy and immunotherapy in patients with recurrent or metastatic disease. The results of some of these studies are available, whereas others are eagerly awaited and will likely shed light on the understanding of MCC biology and potentially improve the clinical outcomes of patients with this rare disease.

Merkel Cell Carcinoma Analysis of Outcomes: A 30-Year Experience

BACKGROUND

Merkel cell carcinoma (MCC) is an aggressive cutaneous malignancy with poor prognosis. Limited data exists to guide treatment decisions. Here we report on our institutional experience and outcomes treating patients with MCC.

METHODS

A database search (1984-2014) of patients treated at the University of Wisconsin Hospital and Clinics was used to identify patients with histologically confirmed MCC. Patient, tumor, and treatment characteristics were examined via review of medical records. Statistical analyses were performed to assess outcomes and associated prognostic factors.

RESULTS

A total of 87 patients with MCC were identified with a median follow-up of 17 months (mean: 38, range: 0-210 months). Two and five-year overall survival rates were 53.9% and 32.8%, respectively. Recurrence was documented in 31.0% of patients (85.2% locoregional, 48.1% distant and 33.3% both). Patients with a history of immunosuppression exhibited significantly worse survival (hazard ratio, 2.01; 95% CI, 1.1-3.7) when compared to immune-competent individuals. The head and neck region was the most common location of primary lesion (N=49) followed by the extremities (N=31). Upper extremity primaries predicted significantly better overall survival (hazard ratio, 0.48; 95% CI, 0.23-0.99) while lower extremity primaries did not have significantly better results (hazard ratio, 0.5; 95% CI, 0.21-1.2) in comparison to head and neck site of primary. Nodal involvement (hazard ratio, 2.95; 95% CI, 1.5-5.79) was also a negative prognostic factor associated with poor overall survival when compared with clinically node negative patients. Primary tumor size > 2 cm (hazard ratio, 1.76; 95% CI, 0.91-3.4) was not associated with survival.

CONCLUSIONS

This study highlights the role of various factors in determining prognosis of Merkel cell carcinoma; history of immunosuppression, nodal involvement, and head/neck primary predicted worse overall survival. These findings suggest that improvements in both distant and locoregionally directed therapies might play an important role in control of MCC and identify areas for future study.

Pure versus combined Merkel cell carcinomas: immunohistochemical evaluation of cellular proteins (p53, Bcl-2, and c-kit) reveals significant overexpression of p53 in combined tumors

Merkel cell polyomavirus is of oncogenic significance in approximately 80% of Merkel cell carcinomas. Morphological subcategories of the tumor differ in regard to viral status, the rare combined type being uniformly virus negative and the predominant pure type being mainly virus positive. Indications that different biological subsets of the tumor exist led us to explore this diversity. In an Eastern Canadian cohort of cases (75 patients; mean age, 76 years [range, 43-91]; male/female ratio, 43:32; 51 [68%] pure and 24 [34%] combined tumors), we semiquantitatively compared the immunohistochemical expression of 3 cellular proteins (p53, Bcl-2, and c-kit) in pure versus combined groups. Viral status was known in a subset of cases. The significant overexpression of p53 in the combined group (mean [SD], 153.8 [117.8] versus 121.6 [77.9]; P = .01) and the increased epidermal expression of this protein (p53 patches) in the same group lend credence to a primary etiologic role for sun damage in these cases. Expression of Bcl-2 and c-kit did not differ significantly between the 2 morphological groups. A relative increase in c-kit expression was significantly associated with a virus-negative status (median [interquartile range], 100 [60-115] versus 70 [0-100]; P = .03). Emerging data reveal divergent biological pathways in Merkel cell carcinoma, each with a characteristic immunohistochemical profile. Virus-positive tumors (all pure) exhibit high retinoblastoma protein and low p53 expression, whereas virus-negative cases (few pure and all combined) show high p53 and relatively high c-kit expression. The potential biological implications of this dichotomy call for consistent stratification of these tumors in future studies.

Mutational analysis of merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine malignancy that is associated with a poor prognosis. The pathogenesis of MCC is not well understood, and despite a recent plethora of mutational analyses, we have yet to find a set of signature mutations implicated in the majority of cases. Mutations, including TP53, Retinoblastoma and PIK3CA, have been documented in subsets of patients. Other mechanisms are also likely at play, including infection with the Merkel cell polyomavirus in a subset of patients, dysregulated immune surveillance, epigenetic alterations, aberrant protein expression, posttranslational modifications and microRNAs. In this review, we summarize what is known about MCC genetic mutations and chromosomal abnormalities, and their clinical significance. We also examine aberrant protein function and microRNA expression, and discuss the therapeutic and prognostic implications of these findings. Multiple clinical trials designed to selectively target overexpressed oncogenes in MCC are currently underway, though most are still in early phases. As we accumulate more molecular data on MCC, we will be better able to understand its pathogenic mechanisms, develop libraries of targeted therapies, and define molecular prognostic signatures to enhance our clinicopathologic knowledge.

Molecular pathology of skin neoplasms of the head and neck

CONTEXT

Skin neoplasms include the most common malignancies affecting humans. Many show an ultraviolet (UV)-induced pathogenesis and often affect the head and neck region.

OBJECTIVE

To review literature on cutaneous neoplasms that show a predilection for the head and neck region and that are associated with molecular alterations.

DATA SOURCES

Literature review.

CONCLUSIONS

Common nonmelanoma skin cancers, such as basal and squamous cell carcinomas, show a UV-induced pathogenesis. Basal cell carcinomas are characterized by molecular alterations of the Hedgehog pathway, affecting patched and smoothened genes. While squamous cell carcinomas show UV-induced mutations in several genes, driver mutations are only beginning to be identified. In addition, certain adnexal neoplasms also predominantly affect the head and neck region and show interesting, recently discovered molecular abnormalities, or are associated with hereditary conditions whose molecular genetic pathogenesis is well understood. Furthermore, recent advances have led to an increased understanding of the molecular pathogenesis of melanoma. Certain melanoma subtypes, such as lentigo maligna melanoma and desmoplastic melanoma, which are more often seen on the chronically sun-damaged skin of the head and neck, show differences in their molecular signature when compared to the other more common subtypes, such as superficial spreading melanoma, which are more prone to occur at sites with acute intermittent sun damage. In summary, molecular alterations in cutaneous neoplasms of the head and neck are often related to UV exposure. Their molecular footprint often reflects the histologic tumor type, and familiarity with these changes will be increasingly necessary for diagnostic and therapeutic considerations.

Prognostic value of CD117 in cancer: a meta-analysis

BACKGROUND

The prognostic value of CD117 expression in cancers has been evaluated for several years while the results remain controversial. We thus performed a systematic review and meta-analysis of studies assessing the impact of CD117 expression on overall survival (OS) and disease-free survival (DFS) to clarify this issue.

METHODS

We searched Pubmed, Embase and Web of Science to identify studies on the prognostic impact of CD117 expression in cancers. A total of 4,458 patients from 39 eligible studies were included in the analysis. Pooled risk ratios (RRs) with 95% confidence interval (95% CI) were calculated to estimate the effect using random-effects model.

RESULTS

The analysis indicated that CD117 had significant association with poor OS of osteosarcoma (OR=1.36, 95% CI=1.03-1.79, I2=0%, fixed model) and renal carcinoma (OR=4.86, 95% CI=2.72-8.67, I2=0%, fixed model).However, no significant association between CD117 and DFS was found in overall studies.

CONCLUSIONS

CD117 expression might be a predictive factor of poor prognosis in some surgically treated cancers, particularly in renal carcinoma.

Gene expression differences predict treatment outcome of merkel cell carcinoma patients

Due to the rarity of Merkel cell carcinoma (MCC), prospective clinical trials have not been practical. This study aimed to identify biomarkers with prognostic significance. While sixty-two patients were identified who were treated for MCC at our institution, only seventeen patients had adequate formalin-fixed paraffin-embedded archival tissue and followup to be included in the study. Patients were stratified into good, moderate, or poor prognosis. Laser capture microdissection was used to isolate tumor cells for subsequent RNA isolation and gene expression analysis with Affymetrix GeneChip Human Exon 1.0 ST arrays. Among the 191 genes demonstrating significant differential expression between prognostic groups, keratin 20 and neurofilament protein have previously been identified in studies of MCC and were significantly upregulated in tumors from patients with a poor prognosis. Immunohistochemistry further established that keratin 20 was overexpressed in the poor prognosis tumors. In addition, novel genes of interest such as phospholipase A2 group X, kinesin family member 3A, tumor protein D52, mucin 1, and KIT were upregulated in specimens from patients with poor prognosis. Our pilot study identified several gene expression differences which could be used in the future as prognostic biomarkers in MCC patients.

Support for p63 expression as an adverse prognostic marker in Merkel cell carcinoma: report on a Canadian cohort

Recent evidence has invoked immunohistochemical expression of p63 in Merkel cell carcinoma as an adverse prognostic factor. Conflicting data led us to evaluate this. An Eastern Canadian cohort diagnosed between 1990 and 2012 was studied. Demographic and clinical data were obtained from pathology records and Provincial Cancer Registries. Pathological features were evaluated by the investigators. Merkel cell polyomavirus status was known in a subset of cases. Clinicopathological features were correlated with overall survival. The cohort consisted of 83 patients (mean age, 75.8 ± 11.7 years) with a male/female ratio of 1.24:1. In a mean follow-up period of 175 weeks (±177), 51 patients died (61.4%). Of several parameters examined, 6 showed significant adverse associations with survival on univariate analysis: age (hazard ratio [HR], 1.05 [1.02-1.08]), clinical stage (III/IV versus I/II; HR, 2.24 [1.18-4.27]), tumor size (HR, 1.16 [1.05-1.28]), combined versus pure morphology (HR, 1.82 [1.04-3.18]), minimal tumor-infiltrating lymphocytes (HR, 2.23 [1.04-4.78]), and expression of p63 (positive in 49.4%; HR, 1.93 [1.09-3.43]). In the stage I/II subgroup, p63 expression was associated with a trend toward poor survival. On multivariate analysis, p63 expression was not significantly associated with reduced survival. Our data support existing evidence that p63 expression in Merkel cell carcinoma carries adverse implications for survival. That it was not an independent prognostic factor may be due to study size and/or its potential as a confounding variable with clinical stage. Of clinical importance is its association with a trend toward a poor outcome in early stage disease.

Specific analysis of KIT and PDGFR-alpha expression and mutational status in Merkel cell carcinoma

BACKGROUND

The purpose of this study was to explore the immunohistochemical and mutational status of the tyrosine kinases KIT and platelet derived growth receptor-alpha (PDGFRA) in Merkel cell carcinoma (MCC). Specifically, we examined the mutated exons in gastrointestinal stromal cell tumors that may confer a treatment response to imatinib mesylate.

METHODS

We evaluated KIT and PDGFRA immunostaining in 23 examples of MCC utilizing laser capture microdissection to obtain pure samples of tumor genomic DNA from 18 of 23 examples of MCC. PCR amplification and sequencing of KIT exons 9, 11, 13 and 17, and PDGFRA exons 10, 12, 14 and 18 for mutations was performed.

RESULTS

Fifteen of 23 tumors (65%) demonstrated CD117 expression and 22 of 23 tumors (95%) demonstrated PDGFRA expression. A single heterozygous KIT exon 11 base change resulting in an E583K mutation was discovered in 12 of 18 (66%) examples of MCC. In addition, a single nucleotide polymorphism was detected in eight of 18 tumors (44%) in exon 18 of PDGFRA (codon 824; GTC > GTT).

CONCLUSIONS

We discovered a novel somatic KIT exon 11 E583K mutation in 66% of tumors. This mutation has been previously described in a human with piebaldism and appears to represent an inactivating mutation. Therefore, despite expression of CD117 and PDGFRA, the absence of activating mutations in these tyrosine kinases makes KIT and PDGFRA unlikely candidates of MCC oncogenesis.

Improved detection suggests all Merkel cell carcinomas harbor Merkel polyomavirus

A human polyomavirus was recently discovered in Merkel cell carcinoma (MCC) specimens. The Merkel cell polyomavirus (MCPyV) genome undergoes clonal integration into the host cell chromosomes of MCC tumors and expresses small T antigen and truncated large T antigen. Previous studies have consistently reported that MCPyV can be detected in approximately 80% of all MCC tumors. We sought to increase the sensitivity of detection of MCPyV in MCC by developing antibodies capable of detecting large T antigen by immunohistochemistry. In addition, we expanded the repertoire of quantitative PCR primers specific for MCPyV to improve the detection of viral DNA in MCC. Here we report that a novel monoclonal antibody detected MCPyV large T antigen expression in 56 of 58 (97%) unique MCC tumors. PCR analysis specifically detected viral DNA in all 60 unique MCC tumors tested. We also detected inactivating point substitution mutations of TP53 in the two MCC specimens that lacked large T antigen expression and in only 1 of 56 tumors positive for large T antigen. These results indicate that MCPyV is present in MCC tumors more frequently than previously reported and that mutations in TP53 tend to occur in MCC tumors that fail to express MCPyV large T antigen.

High KIT and PDGFRA are associated with shorter patients survival in gastroenteropancreatic neuroendocrine tumors, but mutations are a rare event

PURPOSE

(1) To test whether in genomewide expression profiling differentially expressed genes were also distinct on the protein level including KIT and PDGFRA (2) to correlate the expression with clinicopathological parameters (3) to identify activating mutations that might be eligible for tyrosine kinase inhibitor therapy by mutational analysis of tumors with high expression.

METHODS

Gastroenteropancreatic neuroendocrine tumors (GEP NETs) from 119 patients were analyzed for protein expression of ten biomarkers. Mutational analysis of KIT (exon 9, 13, 11 and 17) and PDGFRA (exons 12 and 18) was performed on those samples that showed high protein expression.

RESULTS

High KIT expression was observed in 13% of all specimens, PDGFRA in 33%, CK19 in 26%, CK7 in 2%, CK20 in 5%, S100 in 6%, CD56 in 25%, Chromogranin in 55%, and Synapthophysin in 80%. High expression of KIT and PDGFRA was significantly correlated with shorter disease-specific survival (P = 0.003, P = 0.018, respectively). In multivariate analysis expression of PDGFRA, radicality of surgical treatment and WHO grading influenced disease-specific 10-year survival independently (P = 0.032, P = 0.001 and P = 0.008, respectively). Mutational analysis of highly expressed specimens (n = 51) reveals a novel mutation of KIT in exon 11 (K558N_V559insP) in a well-differentiated metastatic pancreatic neuroendocrine tumor.

CONCLUSIONS

High expression of KIT and PDGFRA was significantly correlated with shorter patients survival and could serve as prognostic marker. Mutations of the KIT gene might open new avenues for tyrosine kinase inhibitor therapy in a subset of patients with advanced pancreatic neuroendocrine tumors.

Huntingtin-interacting protein 1: a Merkel cell carcinoma marker that interacts with c-Kit

Merkel cell carcinoma (MCC) is a neoplasm thought to originate from the neuroendocrine Merkel cells of the skin. Although the prevalence of MCC has been increasing, treatments for this disease remain limited because of a paucity of information regarding MCC biology. We have found that the endocytic oncoprotein Huntingtin-interacting protein 1 (HIP1) is expressed at high levels in ∼90% of MCC tumors and serves as a more reliable histological cytoplasmic stain than the gold standard, cytokeratin 20. Furthermore, high anti-HIP1 antibody reactivity in the sera of a cohort of MCC patients predicts the presence of metastases. Another protein that is frequently expressed at high levels in MCC tumors is the stem cell factor (SCF) receptor tyrosine kinase, c-Kit. In working toward an understanding of how HIP1 might contribute to MCC tumorigenesis, we have discovered that HIP1 interacts with SCF-activated c-Kit. These data not only identify HIP1 as a molecular marker for management of MCC patients but also show that HIP1 interacts with and slows the degradation of c-Kit.

A Review of Carcinomas Arising in the Head and Neck Region in HIV-Positive Patients

The majority of malignancies arising in the head and neck among patients with AIDS are Kaposi sarcoma and non-Hodgkin lymphoma. Patients with HIV/AIDS are also at increased risk of developing several carcinomas of the head and neck. This paper focuses on these less common, albeit important, carcinomas. An English language literature search identified numerous population-based studies evaluating carcinomas in the head and neck of HIV-positive patients. Published results indicate that patients with HIV/AIDS are at an increased risk of developing mucosal squamous cell carcinoma, nasopharyngeal carcinoma, lymphoepithelial carcinoma of the salivary gland, and Merkel cell carcinoma in this anatomic region. Data also suggest that HIV-positive patients with these cancers present at a younger age, with more aggressive disease and worse prognosis compared to HIV-negative patients. Treatment involves surgical resection with or without radiation therapy and chemotherapy for locally advanced and metastatic disease. AIDS patients, however, are more likely to suffer radiation treatment complications. Highly active antiretroviral therapy (HAART) has not altered the incidence of these malignancies.