Patterns of Immunoreactivity with TTF-1 Antibodies 8G7G3/1 and SPT24 Suggest Distinct Immunoprofiles Between Most Pulmonary and Nonpulmonary Small Cell Carcinomas

Introduction. Small cell carcinoma can arise from various sites. Herein, we analyze the ability of 2 thyroid transcription factor-1 (TTF-1) antibodies (SPT24 and 8G7G3/1) to separate pulmonary from nonpulmonary small cell carcinoma. Materials and Methods. We analyzed 26 pulmonary and 83 nonpulmonary small cell carcinomas, and 14 Merkel cell carcinomas. Each tumor was stained with SPT24 and 8G7G3/1. Extent of nuclear staining was scored as diffuse (>50%), focal (11%-50%), rare (1%-10%), or negative (<1%). Results. All pulmonary small cell carcinomas were positive for SPT24 and 8G7G3/1. Four Merkel cell carcinomas (29%) were positive for SPT24 (ranging from rare-to-diffuse), while 2 (14%) showed rare expression with 8G7G3/1. For nonpulmonary small cell carcinomas, 69 (83%) were positive for SPT24 and 40 (48%) were positive for 8G7G3/1. For SPT24 positive tumors, the extent of 8G7G3/1 expression was equal in 17 (25%) and less in 52 tumors (75%), including 29 (42%) that were negative for 8G7G3/1. No nonpulmonary small cell carcinoma had more staining with 8G7G3/1 compared to SPT24. The differences in staining between 8G7G3/1 and SPT24 in the nonpulmonary cohort were statistically significant (P < 0.0001) with no significant difference between primary and metastatic lesions for 8G7G3/1 (P  =  0.66) or SPT24 (P  =  0.77). Conclusion. Most pulmonary small cell carcinomas are diffusely positive for both SPT24 and 8G7G3/1, whereas most nonpulmonary small cell carcinomas exhibit focal-to-no staining with 8G7G3/1 and significantly less staining with 8G7G3/1 compared to SPT24. However, these trends are not absolute and should be interpreted in conjunction with clinical and radiological findings.

Tumor reactive γδ T cells contribute to a complete response to PD-1 blockade in a Merkel cell carcinoma patient

Immunotherapies targeting PD-1/PD-L1 are now widely used in the clinic to treat a variety of malignancies. While most of the research on T cell exhaustion and PD-1 blockade has been focused on conventional αβ T cells, the contribution of innate-like T cells such as γδ T cells to anti-PD-1/PD-L1 mediated therapy is limited. Here we show that tumor reactive γδ T cells respond to PD-1 blockade in a Merkel cell carcinoma (MCC) patient experiencing a complete response to therapy. We find clonally expanded γδ T cells in the blood and tumor after pembrolizumab treatment, and this Vγ2Vδ1 clonotype recognizes Merkel cancer cells in a TCR-dependent manner. Notably, the intra-tumoral γδ T cells in the MCC patient are characterized by higher expression of PD-1 and TIGIT, relative to conventional CD4 and CD8 T cells. Our results demonstrate that innate-like T cells could also contribute to an anti-tumor response after PD-1 blockade.

Moderne Diagnostik und Therapie des Merkelzellkarzinoms

Das Merkelzellkarzinom (MCC) ist ein seltener, aggressiver Hauttumor mit epithelialer und neuroendokriner Differenzierung, dessen Inzidenz in den letzten Jahrzehnten deutlich zugenommen hat. Risikofaktoren sind fortgeschrittenes Lebensalter, heller Hauttyp, UV‐Exposition und Immunsuppression. Pathogenetisch wird ein durch das Merkelzell‐Polyomavirus (MCPyV) hervorgerufener Typ von einem UV‐induzierten Typ mit hoher Tumormutationslast unterschieden.

Klinisch präsentiert sich das MCC als meist schmerzloser, schnell wachsender, rötlich‐violetter Tumor mit glänzender Oberfläche, der bevorzugt im Kopf‐Hals‐Bereich und an den distalen Extremitäten lokalisiert ist. Eine sichere Diagnose kann nur anhand histologischer und immunhistochemischer Merkmale gestellt werden. Bei Erstdiagnose weisen 20%–26% der Patienten lokoregionäre Metastasen und 8%–14% Fernmetastasen auf, weshalb eine Ausbreitungsdiagnostik unabdingbar ist. Bei fehlenden klinischen Hinweisen auf Metastasen wird eine Sentinel‐Lymphknotenbiopsie empfohlen.

Wesentliche Säulen der Therapie sind die Operation, die adjuvante oder palliative Strahlentherapie und in fortgeschrittenen inoperablen Stadien die medikamentöse Tumortherapie. Die Einführung von Immuncheckpoint‐Inhibitoren führte zu einem Paradigmenwechsel, da sich hiermit ein wesentlich langfristigeres Ansprechen und bessere Überlebensraten als mit Chemotherapie erreichen lassen. Zur Therapie des metastasierten MCC ist in Deutschland der PD‐L1‐Inhibitor Avelumab zugelassen, aber auch die PD‐1‐Antikörper Pembrolizumab und Nivolumab werden mit Erfolg eingesetzt. Adjuvante und neoadjuvante Therapiekonzepte, Immunkombinationstherapien und zielgerichtete Therapien als Monotherapie oder in Kombination mit Immuncheckpoint‐Inhibitoren befinden sich in klinischer Prüfung.

Dissecting the tumour immune microenvironment in merkel cell carcinoma based on a machine learning framework

Merkel cell carcinoma (MCC) is a primary cutaneous neoplasm of neuroendocrine carcinoma of the skin, which is characterized by molecular heterogeneity with diverse tumour microenvironment (TME). However, we are still lack knowledge of the cellular states and ecosystems in MCC. Here, we systematically identified and characterized the landscape of cellular states and ecotypes in MCC based on a machine learning framework. We obtained 30 distinct cellular states from 9 immune cell types and investigated the B cell, CD8 T cell, fibroblast, and monocytes/macrophage cellular states in detail. The functional profiling of cellular states were investigated and found the genes highly expressed in cellular states were significantly enriched in immune- and cancer hallmark-related pathways. In addition, four ecotypes were further identified which were with different patient compositions. Transcriptional regulation analysis revealed the critical transcription factors (i.e. E2F1, E2F3 and E2F7), which play important roles in regulating the TME of MCC. In summary, the findings of this study may provide rich 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.

Cutaneous Neuroendocrine Mucinous Carcinomas Are Low-grade But May Be Associated With Other Cancers

Primary cutaneous mucinous sweat gland carcinoma is said to be prognostically stratifiable by neuroendocrine differentiation, however, this assertion is based on historical data and older staining techniques. We aimed to evaluate the percentage of mucinous and nonmucinous adnexal tumors expressing the newer, more sensitive neuroendocrine marker insulinoma-associated protein 1 (INSM1), and to assess clinicopathologic features in patients cohorted by this phenotype. Of 12 available adnexal/cutaneous adenocarcinomas, 9 were mucinous, 3/9 of which were INSM1-negative, and 2/3 with nodal metastases. Of 3 nonmucinous cases, all were INSM1-negative, 1/3 with nodal metastasis, and 2/3 with lymphovascular invasion. In contrast, of 6 mucinous INSM1-positive cases, no cases had LVI or metastasis, however, 3 patients died during follow-up, 2 from breast or urothelial cancer. A fourth patient developed breast carcinoma. INSM1-positive tumors, from cheek (3), scalp (2), and chin (1) were estrogen receptor and progesterone receptor positive. No cases of apocrine adenoma or hidrocystoma, basal cell, or sebaceous carcinoma labeled with INSM1. While most primary cutaneous mucinous carcinomas are of the neuroendocrine type, our study confirms the presence of occasional non-neuroendocrine mucinous carcinomas. We validate the association of such tumors and nonmucinous non-neuroendocrine adnexal carcinoma with intermediate-grade behavior, including lymph node metastases, but not death. Conversely, neuroendocrine expressing primary cutaneous mucinous carcinoma may represent the well-differentiated neuroendocrine neoplasm/neuroendocrine tumor primary to skin, with low-grade behavior, but attendant risk of germline susceptibility to other aggressive extracutaneous tumors. Routine assessment of cutaneous adnexal carcinoma with INSM1 and longer term follow-up and cancer screening of patients with positive staining is recommended.

Somatostatin receptor expression in Merkel cell carcinoma: correlation with clinical data

BACKGROUND

Merkel cell carcinoma (MCC) is a rare, high-grade neuroendocrine neoplasm (NEN) of the skin. Somatostatin receptors (SSTRs) are G protein-linked receptors that regulate cell proliferation and growth. SSTRs are expressed in many NENs; however, scant information is available on their expression in MCCs or their association with clinical parameters and patient outcomes.

MATERIAL AND METHODS

This retrospective study was conducted at Helsinki University Hospital and the University of Helsinki. Using a tissue microarray, we investigated SSTR1-5 expression by immunohistochemistry in 99 MCC tissue samples. Samples were collected between 1983 and 2017 and coupled with the patients' clinical data.

RESULTS

SSTR2-SSTR5 were detected in 69%, 6%, 4%, and 1% of the tumours, respectively. However, SSTR1 expression was not observed. Cytoplasmic SSTR2 positivity was associated with metastatic disease at the time of diagnosis (p = 0.009), but it did not correlate with disease-specificity or overall survival.

CONCLUSION

SSTR2-5 expression was observed in MCCs. In particular, SSTR2 expression is clinically valid because it is associated with metastatic disease at the time of diagnosis and can thus serve as a prognostic marker. Moreover, SSTR2 overexpression provides a molecular basis for tumour imaging and treatment with somatostatin analogues.

LAMP1 targeting of the large T antigen of Merkel cell polyomavirus results in potent CD4 T cell responses and tumor inhibition

Introduction

Most cases of Merkel cell carcinoma (MCC), a rare and highly aggressive type of neuroendocrine skin cancer, are associated with Merkel cell polyomavirus (MCPyV) infection. MCPyV integrates into the host genome, resulting in expression of oncoproteins including a truncated form of the viral large T antigen (LT) in infected cells. These oncoproteins are an attractive target for a therapeutic cancer vaccine.

Methods

We designed a cancer vaccine that promotes potent, antigen-specific CD4 T cell responses to MCPyV-LT. To activate antigen-specific CD4 T cells in vivo, we utilized our nucleic acid platform, UNITE™ (UNiversal Intracellular Targeted Expression), which fuses a tumor-associated antigen with lysosomal-associated membrane protein 1 (LAMP1). This lysosomal targeting technology results in enhanced antigen presentation and potent antigen-specific T cell responses. LTS220A, encoding a mutated form of MCPyV-LT that diminishes its pro-oncogenic properties, was introduced into the UNITE™ platform.

Results

Vaccination with LTS220A-UNITE™ DNA vaccine (ITI-3000) induced antigen-specific CD4 T cell responses and a strong humoral response that were sufficient to delay tumor growth of a B16F10 melanoma line expressing LTS220A. This effect was dependent on the CD4 T cells' ability to produce IFNγ. Moreover, ITI-3000 induced a favorable tumor microenvironment (TME), including Th1-type cytokines and significantly enhanced numbers of CD4 and CD8 T cells as well as NK and NKT cells. Additionally, ITI-3000 synergized with an α-PD-1 immune checkpoint inhibitor to further slow tumor growth and enhance survival.

Conclusions

These findings strongly suggest that in pre-clinical studies, DNA vaccination with ITI-3000, using the UNITE™ platform, enhances CD4 T cell responses to MCPyV-LT that result in significant anti-tumor immune responses. These data support the initiation of a first-in-human (FIH) Phase 1 open-label study to evaluate the safety, tolerability, and immunogenicity of ITI-3000 in patients with polyomavirus-positive MCC (NCT05422781).

Risk of Nonkeratinocyte Skin Cancers in People Living with HIV during the Era of Antiretroviral Therapy

Antiretroviral therapy may alter susceptibility to nonkeratinocyte skin cancers (NKSCs) by improving immunity in people living with HIV. Using linked data from HIV and cancer registries in 12 states/regions in the United States during the antiretroviral therapy era (1996‒2018), we calculated standardized incidence ratios for 27 NKSCs, comparing incidence with that of the general population. Risk factors for NKSCs were evaluated using Poisson regression. There were 2,743 NKSCs diagnosed in 585,706 people living with HIV followed for 4,575,794 person-years. Kaposi sarcoma was the most common cancer (82%), followed by melanoma (12%) and cutaneous lymphoma (2.6%). Incidence was elevated for virus-related NKSCs: Kaposi sarcoma (standardized incidence ratio = 147, 95% confidence interval = 141‒153), diffuse large B-cell lymphoma (standardized incidence ratio = 5.19, 95% confidence interval = 3.13‒8.11), and Merkel cell carcinoma (standardized incidence ratio = 3.15, 95% confidence interval = 1.93‒4.87); elevated incidence for diffuse large B-cell lymphoma and Merkel cell carcinoma was observed only among people living with HIV with a previously acquired immunodeficiency syndrome diagnosis. Kaposi sarcoma risk was highest among men who have sex with men. Incidence was not increased for melanoma, adnexal carcinomas, and sarcomas. Melanoma and Merkel cell carcinoma arose disproportionately on sun-exposed skin, supporting a role for UVR in their development. In conclusion, risk for most NKSCs was similar to that of the general population during the antiretroviral therapy era, suggesting that people living with HIV without NKSC risk factors may not require intensive skin surveillance.

Prognostic significance of tumour budding in Merkel cell carcinoma

Prognostic factors in Merkel cell carcinoma (MCC) are scarce. Tumour budding (TB) has been shown to have a prognostic role in different cancers but has not been explored in MCC. We aimed to determine if TB influences survival in MCC. We performed a retrospective evaluation of 45 cases of MCC in a cancer centre. This included a survival analysis involving TB in patients with MCC, and we searched for variables associated with TB. The mean age of the patients was 69 years. Histologically, the average Breslow was 11.36 mm, and the mean mitotic rate was 31.9 mitoses/mm2. The diagnosis was made in clinical stages I and II in 40% of cases, 22.2% in stage III, and 37.8% in stage IV. Tumour budding was low ( 10 buds/0.785 mm2) in 24.4%. There were no clinical or pathological features associated with high TB. Among the prognostic factors for 5-year survival, we found that tumour size and clinical stage were statistically associated with survival (p = 0.031 and 0.021), but TB was not. No clinical or pathological characteristics of MCC are associated with any degree of TB. Tumour budding does not influence overall survival.

Merkel cell polyomavirus small T antigen is a viral transcription activator that is essential for viral genome maintenance

Merkel cell polyomavirus (MCV) is a small DNA tumor virus that persists in human skin and causes Merkel cell carcinoma (MCC) in immunocompromised individuals. The multi-functional protein MCV small T (sT) activates viral DNA replication by stabilizing large T (LT) and promotes cell transformation through the LT stabilization domain (LTSD). Using MCVΔsT, a mutant MCV clone that ablates sT, we investigated the role of sT in MCV genome maintenance. sT was dispensable for initiation of viral DNA replication, but essential for maintenance of the MCV genome and activation of viral early and late gene expression for progression of the viral lifecycle. Furthermore, in phenotype rescue studies, exogenous sT activated viral DNA replication and mRNA expression in MCVΔsT through the LTSD. While exogenous LT expression, which mimics LT stabilization, increased viral DNA replication, it did not activate viral mRNA expression. After cataloging transcriptional regulator proteins by proximity-based MCV sT-host protein interaction analysis, we validated LTSD-dependent sT interaction with four transcriptional regulators: Cux1, c-Jun, BRD9, and CBP. Functional studies revealed Cux1 and c-Jun as negative regulators, and CBP and BRD9 as positive regulators of MCV transcription. CBP inhibitor A-485 suppressed sT-induced viral gene activation in replicating MCVΔsT and inhibited early gene expression in MCV-integrated MCC cells. These results suggest that sT promotes viral lifecycle progression by activating mRNA expression and capsid protein production through interaction with the transcriptional regulators. This activity is essential for MCV genome maintenance, suggesting a critical role of sT in MCV persistence and MCC carcinogenesis.

Morphological patterns of metastases from combined Merkel cell carcinomas: study of an eastern Canadian cohort of cases

Combined Merkel cell carcinomas are hybrid tumors composed of neuroendocrine and other phenotypic (usually squamous) elements. They form a minority of Merkel cell carcinomas (MCCs) as a whole, are usually Merkel cell polyomavirus-negative, and have rarely been segregated for specific study. Sporadic reports have indicated that metastases from these tumors can show a combined phenotype. We retrospectively studied 38 cases (24 men [63%], 14 women [37%], mean age 78 years [range, 46-99 years]) of combined MCC. Metastases occurred in 20 patients (53%) (at presentation and/or in follow-up [mean 38 months (range, 0.6-185 months)]). Those from 17 individuals (45%) were examined microscopically. These were mainly nodal in distribution. In 12 patients (71%), the secondary deposits were of pure neuroendocrine type, whereas in 5 (29%), combined deposits were identified. Squamous elements were the most common divergent component, in the primary and secondary tumors. The combined metastases varied from obvious squamous nests in a neuroendocrine background to scattered bizarre tumor giant cells expressing CK5/6 on immunohistochemistry. In one case, individual nodes within a single basin displayed purely squamous or purely neuroendocrine deposits. The mean overall survival in the cohort was 48 months (range, 30-67 months) and the mortality was 82%. Our work sheds light on the frequency and patterns of metastases in combined MCCs. In concert with the poor outcome data documented by others, it also raises a question as to the potential prognostic significance of a combined phenotype per se, independent of a virus-negative status and other variables. This issue deserves further study.

Current In Vitro and In Vivo Models to Study MCPyV-Associated MCC

Merkel cell polyomavirus (MCPyV) is the only human polyomavirus currently known to cause human cancer. MCPyV is believed to be an etiological factor in at least 80% of cases of the rare but aggressive skin malignancy Merkel cell carcinoma (MCC). In these MCPyV+ MCC tumors, clonal integration of the viral genome results in the continued expression of two viral proteins: the viral small T antigen (ST) and a truncated form of the viral large T antigen. The oncogenic potential of MCPyV and the functional properties of the viral T antigens that contribute to neoplasia are becoming increasingly well-characterized with the recent development of model systems that recapitulate the biology of MCPyV+ MCC. In this review, we summarize our understanding of MCPyV and its role in MCC, followed by the current state of both in vitro and in vivo model systems used to study MCPyV and its contribution to carcinogenesis. We also highlight the remaining challenges within the field and the major considerations related to the ongoing development of in vitro and in vivo models of MCPyV+ MCC.

Comparison of Quantitative Real-Time PCR and Digital PCR to Detect the Polyomavirus in Merkel Cell Carcinoma

Merkel cell polyomavirus (MCPyV) prevalence in Merkel cell carcinoma (MCC) cases is controversial. The detection and quantification of MCPyV DNA is mainly performed by PCR techniques using formalin-fixed, paraffin-embedded (FFPE) tissues. The aim of this study is to compare the performance of two different molecular techniques, specifically the quantitative Real-Time PCR (qPCR) and digital PCR (dPCR). Samples from 31 cases of MCC excisional surgical biopsies were analyzed. DNA extraction and purification from clinical samples were performed using the QIAcube Qiagen automated nucleic acid extractor. After the extraction, MCPyV was detected by qPCR and dPCR using specially designed primers and probes. Of the 31 MCC samples under study, the MCPyV genome was detected in 11 samples (35%) by qPCR compared with 20 samples (65%) detected by dPCR. Notably, 65% of primary tumors were positive for MCPyV (15/23). The viral genome was detected in 75% of tumors located at UV-exposed sites (6/8), 55% of tumors at partially UV-protected sites (5/9), and 67% of tumors at UV-protected sites (4/6). Our results showed a better sensitivity of dPCR in detecting the MCPyV genome in MCC samples compared with traditional qPCR techniques.

Merkel cell polyomavirus large T antigen binding to pRb promotes skin hyperplasia and tumor development

Clear evidence supports a causal link between Merkel cell polyomavirus (MCPyV) and the highly aggressive human skin cancer called Merkel cell carcinoma (MCC). Integration of viral DNA into the human genome facilitates continued expression of the MCPyV small tumor (ST) and large tumor (LT) antigens in virus-positive MCCs. In MCC tumors, MCPyV LT is truncated in a manner that renders the virus unable to replicate yet preserves the LXCXE motif that facilitates its binding to and inactivation of the retinoblastoma tumor suppressor protein (pRb). We previously developed a MCPyV transgenic mouse model in which MCC tumor-derived ST and truncated LT expression were targeted to the stratified epithelium of the skin, causing epithelial hyperplasia, increased proliferation, and spontaneous tumorigenesis. We sought to determine if any of these phenotypes required the association between the truncated MCPyV LT and pRb. Mice were generated in which K14-driven MCPyV ST/LT were expressed in the context of a homozygous RbΔLXCXE knock-in allele that attenuates LT-pRb interactions through LT's LXCXE motif. We found that many of the phenotypes including tumorigenesis that develop in the K14-driven MCPyV transgenic mice were dependent upon LT's LXCXE-dependent interaction with pRb. These findings highlight the importance of the MCPyV LT-pRb interaction in an in vivo model for MCPyV-induced tumorigenesis.

The texture of collagen in the microenvironments of Merkel cell carcinoma

ABSTRACT

Solid tumors typically contain high levels of fibrillar collagen. The increased stromal collagen deposition usually promotes cancer progression since biochemical and biophysical cues from tumor-associated collagen fibers stimulate neoplastic cells. Few studies have investigated the relationship between Merkel cell carcinoma (MCC) and the extracellular matrix (ECM), but there are no works evaluating collagen.This is an observational, analytical, retrospective study including 11 patients with MCC. Primary tumor-stained sections were evaluated by second harmonic generation microscopy and texture analysis.Peritumoral texture features (area fraction, mean gray value, entropy, and contrast) showed much lower values than normal skin (P < .0001) revealing extensively altered structure of peritumoral collagen fibers. These differences were not significant between tumors with unfavorable and favorable known prognostic factors.Profound changes in collagen fibers present in the stroma accompanying primary MCC may contribute to the aggressive behavior of this tumor. Our results indicate that whatever MCC histological subtype, size or anatomical location, MCC promotes the same type of ECM for its development. As an outlook, therapies using ECM macromolecules or fibroblasts (the architects of ECM remodeling) as target could be useful in the treatment of MCC.

Merkel cell carcinoma of the head and neck in the south-east of England

Merkel cell carcinoma (MCC) is a rare and highly aggressive neuroendocrine malignancy of the skin. Its incidence is increasing with half of cases involving the head and neck. To the best of our knowledge, few large studies have been published in the UK, and to date this is the largest reported series of head and neck MCC. We retrospectively reviewed the outcomes of patients with MCC in three hospitals in the south-east of England over a 12-year period (2008-2019). Diagnosis was based on histological data following biopsy. Overall survival and disease-specific survival were calculated using Kaplan-Meier and log-rank tests. Fifty-eight patients met the inclusion criteria (24 stage I, 22 stage II, 9 stage III, and 3 unclassified). Median disease-free survival was 36 months (95% CI 0 to 77.2) and median overall survival 50 months (95% CI 29.9 to 70). Overall five-year survival was 34.4% (95% CI 17% to 52%) with two-year survival at 62% (95% CI 48% to 76%). Five-year disease-free survival was 26.7% (95% CI 17 to 52%) with two-year disease-free survival at 54% (95% CI 40% to 68%). To date, this is the largest UK based study reporting overall and disease-free survival associated with MCC of the head and neck. Half the patients presented late, and surgery was the mainstay of treatment, augmented by adjuvant radiotherapy. There is a need to better stratify patients at risk of developing metastatic disease, with the use of sentinel lymph node biopsy and positron-emission tomography-computed tomography (PET-CT), as immunotherapy and targeted agents are now available to treat advanced disease.

Efficacy of Electrochemotherapy in the Treatment of Cutaneous Melanoma Metastases and Rare Non-melanoma Skin Cancer

BACKGROUND

We aimed to verify the clinical efficacy and safety of the electrochemotherapy in melanoma metastases and in cases of rare non-melanoma tumors that were difficult to treat for the specific anatomical site or for patient comorbidities.

PATIENTS AND METHODS

We treated 68 patients (699 cutaneous nodules), 44 patients with metastatic melanomas and 24 patients with non-melanoma tumors, at the Melanoma & Skin Cancer Unit, Florence, Italy.

RESULTS

We obtained an objective response of 89.7% (88.6% in melanomas and 91.7% in non-melanoma tumors), complete response 54.4% and partial response 35.3%.

CONCLUSION

This study showed that electrochemotherapy is effective in the treatment of melanoma metastases and in rare types of non-melanoma tumors. In particular, we successfully treated rare tumors as angiosarcoma, pleomorphic sarcoma, myxofibrosarcoma, sarcoma di Kaposi, porocarcinoma, sebaceous carcinoma, Merkel cell carcinoma, malignant blue nevus, undifferentiated epitheliomorphic cell neoplasia and metastases from thyroid carcinoma. No serious adverse events were observed.

Impact of Tumor-Infiltrating Lymphocytes on Overall Survival in Merkel Cell Carcinoma

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine carcinoma of the skin. As the clinical course can be variable, prognostic markers are needed to better stratify patients. Prior literature, composed of small series with limited sample size, has demonstrated that tumor-infiltrating lymphocytes (TILs) are an important prognostic marker in MCC. To validate these findings on a population level, we sought to analyze and report the prognostic value of TILs in a large national data set.

MATERIALS AND METHODS

A retrospective observational cohort study was conducted of patients with nonmetastatic MCC from 2010 to 2015 using the National Cancer Database. Individual variables trending toward significance using a univariable analysis were included in a multivariable Cox proportional hazards model to assess their independent effect on overall survival (OS). TILs were subclassified into none, nonbrisk, and brisk and the survival analysis was performed. Propensity score-weighted multivariable analysis (PS MVA) was performed to adjust for additional confounding.

RESULTS

A total of 2,182 patients met inclusion criteria: 611 (28.0%) were identified as having TILs present, and 1,571 (72.0%) had TILs absent in the tumor. On MVA, subdivision of TIL status into nonbrisk (hazard ratio [HR], 0.750; 95% confidence interval [CI], 0.602-0.933) and brisk (HR, 0.499; 95% CI, 0.338-0.735) was associated with incrementally improved OS compared with no TILs. The association of nonbrisk and brisk TILs with improved OS was retained on PS MVA (Nonbrisk: HR, 0.720; 95% CI, 0.550-0.944; Brisk: HR, 0.483; 95% CI, 0.286-0.814).

CONCLUSION

The presence of nonbrisk and brisk TILs is associated with incrementally improved OS in patients with nonmetastatic MCC in a large national data set. This pathologic feature can aid with risk stratification, estimation of prognosis, and, importantly, decision-making with respect to treatment intensification in high-risk patients.

IMPLICATIONS FOR PRACTICE

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cutaneous malignancy with variable clinical course. Prognostic markers are needed to better risk stratify patients. We present the largest retrospective observational cohort study of patients with nonmetastatic MCC using the National Cancer Database. Our analysis demonstrates an association between increasing degrees of tumor-infiltrating lymphocytes and incrementally improved survival. These conclusions improve pathologic risk stratification, and decision-making with respect to treatment intensification. Intensification may include adjuvant radiation therapy to the primary site after wide excision despite small tumor size, to the nodal basin in sentinel lymph node-negative patients, or offering closer follow-up.

[MERKEL CELL CARCINOMA: A RETROSPECTIVE STUDY]

BACKGROUND

Merkel Cell Carcinoma (MCC) is an aggressive neuroendocrine skin cancer. Though rare, in recent decades its prevalence has increased, and its incidence has tripled.

OBJECTIVES

To describe a cohort of MCC patients treated at a referral center in northern Israel, and to compare their characteristics and course of illness to cases reported in the literature.

METHODS

A retrospective review of 18 MCC patients treated in the Plastic Surgery Department at the Rambam Health Care Campus between the years 2011-2016. Patient demographics, medical history, histological findings, systemic involvement, adjuvant therapy, recurrence and survival rates parameters were collected and analyzed.

RESULTS

Study group patients were predominantly elderly, mostly men, and mainly Caucasian. A few were immunocompromised. Melanoma and MCC are known to be linked, and indeed, about a quarter of the patients suffered previously from melanoma. Diabetes, although not described as an MCC risk factor, has accounted for about 50% of cases, more than 5 times its prevalence in the general population. Tumor and metastases distribution were similar to the literature. Metastases were found in about 20% of cases at diagnosis. In one third of the patients, lymph nodes were already involved during surgery, with recurrence rates of 50%, and 40% mortality in five years.

CONCLUSIONS

Study results, for the first time, imply that there might be an association between diabetes and MCC. A link that could explain the rise of MCC incidence in recent decades. In addition, treatment guidelines were defined for metastatic disease which include the novel immunotherapy as a central component in treatment; hopefully, to improve patients' prognosis in this life-threatening disease.

Merkel cell carcinoma with squamous differentiation - case report

We report a case of 81-year old female with Merkel cell carcinoma of skin with squamous differentiation and aberrant immunohistochemical profile. Primary skin tumor of left preauricular area was incompletely removed 6 months ago and diagnosed as poorly differentiated squamous cell carcinoma. After 6 months patient returns with relapse and new biopsy is made. Microscopically, mostly solid structures of poorly differentiated neoplasia with focal squamous differentiated are found. Neoplastic cells were small, polygonal, with scant cytoplasm and irregular oval dark nuclei with high mitotic activity. Immunohistochemically, tumor cells showed positivity for AE1/AE3, p63, CD56, chromogranin A, synaptophysin and in squamous parts p40. CK20 and other markers examined were negative. Merkel cell carcinoma is rare and highly aggressive skin tumor with characteristic expression of epithelial and neuroendocrine markers. In this report we want to point out that caution should be taken in excluding diagnosis of Merkel cell carcinoma from differential diagnosis based on atypical histological and immunohistochemical findings, especially the risk of confusion with less aggressive skin tumors.

Recent advances in Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer that has been historically associated with limited treatment options and poor prognosis. In the past 10 years, research in MCC has progressed significantly, demonstrating improved outcomes when treating with immunotherapy, particularly PD-1/PD-L1 inhibitors, when compared with conventional chemotherapy. There is also increasing evidence of the abscopal effect, a phenomenon describing the regression of untreated, distant MCC tumors following local radiation therapy. Additionally, antibodies to Merkel cell polyomavirus oncoproteins have been found to correlate with disease burden in a subset of patients, providing a useful tool for surveillance after treatment. Guidelines for the management of MCC will likely continue to change as research on surveillance and treatment of MCC continues.

A pilot study of alternative TrkAIII splicing in Merkel cell carcinoma: a potential oncogenic mechanism and novel therapeutic target

BACKGROUND

Merkel cell carcinomas (MCCs) are rare, aggressive, therapeutically-challenging skin tumours that are increasing in incidence and have poor survival rates. The majority are caused by genomic Merkel cell polyomavirus (MCPyV) integration and MCPyV T-antigen expression. Recently, a potential oncogenic role for the tropomyosin-related tyrosine kinase A receptor (TrkA) has been proposed in MCC. Alternative TrkAIII splicing is a TrkA oncogenic activation mechanism that can be promoted by SV40 large T-antigen, an analogue of MCPyV large T-antigen. In this pilot study, therefore, we have evaluated TrkAIII splicing as a novel potential oncogenic mechanism and therapeutic target in MCPyV positive MCC.

METHODS

Formalin-fixed paraffin-embedded MCC tissues, consisting of 10 stage IV, 1 stage IIIB, 1 stage IIB, 4 stage IIA and 2 stage I tumours, from patients diagnosed and treated from September 2006 to March, 2019, at the University of L'Aquila, L'Aquila, Italy, were compared to 3 primary basal cell carcinomas (BCCs), 3 primary squamous cell carcinomas (SCCs) and 2 normal skin samples by RT-PCR for MCPyV large T-antigen, small T-antigen, VP-1 expression and alternative TrkAIII splicing and by indirect IF for evidence of intracellular TrkA isoform expression and activation.

RESULTS

9 of 10 Recurrent stage IV MCCs were from patients (P.1-3) treated with surgery plus loco-regional Melphalan chemotherapy and remaining MMCs, including 1 stage IV tumour, were from patients treated with surgery alone (P. 4-11). All MCPyV positive MCCs exhibiting MCPyV large T-antigen expression (17 of 18MCCs, 90%) exhibited alternative TrkAIII mRNA splicing (100%), which was exclusive in a significant number and predominant (> 50%) in all stage IV MCCs and the majority of stage 1-III MCCs. MCCs with higher TrkAIII to 18S rRNA expression ratios also exhibited strong or intermediate immunoreactivity to anti-TrkA antibodies, consistent with cytoplasmic TrkAIII expression and activation. In contrast, the MCPyV negative MCC, BCCs, SCCs and normal skin tissues all exhibited exclusive fully-spliced TrkA mRNA expression, associated with variable immunoreactivity for non-phosphorylated but not phosphorylated TrkA.

CONCLUSIONS

MCPyV positive MCCs but not MCPyV negative MCC, BCCs and SCCs exhibit predominant alternative TrkAIII splicing, with evidence of intracellular TrkAIII activation. This establishes a new potential MCC subset, unveils a novel potential MCPyV oncogenic mechanism and identifies TrkAIII as a novel potential therapeutic target in MCPyV positive MCC.

Psychometric Properties of EQ-5D-5L Scoring Algorithms for the United Kingdom in Metastatic Merkel Cell Carcinoma

BACKGROUND

Currently, there are 4 EQ-5D-5L scoring algorithms available for the United Kingdom that can be used to derive a utility score.

OBJECTIVES

To perform a psychometric validation of the EQ-5D utility score in patients with metastatic Merkel cell carcinoma (mMCC) and to compare 4 EQ-5D-5L value sets currently available for the United Kingdom.

METHODS

Data collected in the phase 2 trial JAVELIN Merkel 200 were analyzed, in which 88 patients with mMCC were treated with avelumab. Utility scores were calculated using the EQ-5D-5L valuation set by Devlin et al and 3 further algorithms that are based on EQ-5D-3L valuations. Criterion validity was assessed by Pearson correlations between utility and other HRQoL scales. Responsiveness was assessed by correlating change in utility scores with change in HRQoL scales and percentage change in tumor size. Effect sizes for change from baseline in utility were calculated in subgroups of patients with improving and deteriorating health based on clinically relevant changes in various external anchors.

RESULTS

Devlin utilities were up to 0.10 points higher than utilities calculated from EQ-5D-3L valuations. Large correlations (0.45-0.72; P < .01) between utility and the EuroQol Visual Analogue Scale and FACT-G total, physical, and functional scores were found for all 4 algorithms. Large correlations between these measures were also found for change from baseline scores. In patients with health improvements, effect sizes were larger for the 3 EQ-5D-3L-based algorithms, whereas the Devlin utilities had larger effect sizes for health deteriorations, probably because of different levels of baseline utility.

CONCLUSIONS

The English National Institute for Health and Care Excellence currently recommends use of the 3L valuation sets. Our analyses show that all 4 scoring algorithms have good and similar psychometric properties in patients with mMCC.

Discovery of a new human polyomavirus associated with trichodysplasia spinulosa in an immunocompromized patient

The Polyomaviridae constitute a family of small DNA viruses infecting a variety of hosts. In humans, polyomaviruses can cause infections of the central nervous system, urinary tract, skin, and possibly the respiratory tract. Here we report the identification of a new human polyomavirus in plucked facial spines of a heart transplant patient with trichodysplasia spinulosa, a rare skin disease exclusively seen in immunocompromized patients. The trichodysplasia spinulosa-associated polyomavirus (TSV) genome was amplified through rolling-circle amplification and consists of a 5232-nucleotide circular DNA organized similarly to known polyomaviruses. Two putative “early” (small and large T antigen) and three putative “late” (VP1, VP2, VP3) genes were identified. The TSV large T antigen contains several domains (e.g. J-domain) and motifs (e.g. HPDKGG, pRb family-binding, zinc finger) described for other polyomaviruses and potentially involved in cellular transformation. Phylogenetic analysis revealed a close relationship of TSV with the Bornean orangutan polyomavirus and, more distantly, the Merkel cell polyomavirus that is found integrated in Merkel cell carcinomas of the skin. The presence of TSV in the affected patient's skin was confirmed by newly designed quantitative TSV-specific PCR, indicative of a viral load of 10⁵ copies per cell. After topical cidofovir treatment, the lesions largely resolved coinciding with a reduction in TSV load. PCR screening demonstrated a 4% prevalence of TSV in an unrelated group of immunosuppressed transplant recipients without apparent disease. In conclusion, a new human polyomavirus was discovered and identified as the possible cause of trichodysplasia spinulosa in immunocompromized patients. The presence of TSV also in clinically unaffected individuals suggests frequent virus transmission causing subclinical, probably latent infections. Further studies have to reveal the impact of TSV infection in relation to other populations and diseases.

Diseases that occur exclusively in immunocompromized patients are often of an infectious nature. Trichodysplasia spinulosa (TS) is such a disease characterized by development of papules, spines and alopecia in the face. Fortunately this disease is rare, because facial features can change dramatically, as in the case of an adolescent TS patient who was on immunosuppressive drugs because of heart-transplantation. A viral cause of TS was suspected already for some time because virus particles had been seen in TS lesions. In pursuit of this unknown virus, we isolated DNA from collected TS spines and could detect a unique small circular DNA suggestive of a polyomavirus genome. Additional experiments confirmed the presence in these samples of a new polyomavirus that we tentatively called TS-associated polyomavirus (TSPyV or TSV). TSV shares several properties with other polyomaviruses, such as genome organization and proteome composition, association with disease in immunosuppressed patients and occurence in individuals without overt disease. The latter indicates that TSV circulates in the human population. Future studies have to show how this newly identified polyomavirus spreads, how it causes disease and if it is related to other (skin) conditions as well.

Carcinoma metastasis to unexpected synchronous lymphoproliferative disorder: report of three cases and review of literature

Metastasis of one cancer to another cancer is rare. This report describes three cases in which low grade non-Hodgkin lymphomas were incidentally detected during the examination of lymph nodes removed as part of treatment of a previously diagnosed malignancy.

[Merkel cell carcinoma: descriptive study of 24 cases (1993-2001)]

INTRODUCTION

Merkel cell carcinoma (MCC) is a rare skin tumor with a highly malignant nature whose appropriate treatment is still debated. Wide surgery is the treatment of choice, but the question concerning protocols for adjuvant radiotherapy or chemotherapy remains open.

PATIENTS AND METHODS

A retrospective analysis of 24 cases of MCC collected over a period of 9 years was performed, focusing on clinical and histologic features, and response to treatment.

RESULTS

There were 17 women and 7 men with a mean age of 74.3 years. The median follow up was 34 months. The annual incidence per 100,000 habitants was 0.378. The head and neck localization was predominant (54%). Fifteen (68%) of patients presented with local disease (stage I), and 32% of patients presented with regional node (stage II) or distant metastases (stage III). Patients with stage I had a 5-years overall survival rate of 73,85%. Among them, five patients (33%) developed a local or nodal recurrence, although two patients were initially treated with surgery and local post-operative radiotherapy. Patients with stage II and III demonstrated a 5-year overall survival rate of 51,43%.

DISCUSSION

Our series illustrates the clinical characteristics of this tumor of the elderly, which is mainly located on head and neck and associated with a poor prognosis. Treatments are discussed.

Primary cutaneous neuroendocrine (Merkel cell) carcinoma in association with squamous- and basal-cell carcinoma

The co-existence of squamous-cell carcinoma (SCC) and neuroendocrine (Merkel cell) carcinoma (NEC) of the skin has been well documented in several patients. The concurrent development of NEC and basal-cell carcinoma (BCC) in the same cutaneous lesion, on the other hand, has not been reported. We describe a 68-year-old man presenting with NEC, SCC, and BCC arising at the same site in retroauricular skin. Cells of NEC and SCC showed an intermingled pattern of growth, whereas those of BCC were "embedded" among those of the other two tumors. Immunohistochemical stains were consistent with the histopathologic diagnosis. We believe that this is the first report of the association of NEC, SCC, and BCC in the same skin lesion.

Radiation sensitivity of Merkel cell carcinoma cell lines

PURPOSE

Merkel cell carcinoma (MCC), being a small cell carcinoma, would be expected to be sensitive to radiation. Clinical analysis of patients at our center, especially those with macroscopic disease, would suggest the response is quite variable. We have recently established a number of MCC cell lines from patients prior to radiotherapy, and for the first time are in a position to determine their sensitivity under controlled conditions.

METHODS AND MATERIALS

Some of the MCC lines grew as suspension cultures and could not be single cell cloned; therefore, it was not possible to use clonogenic survival for all cell lines. A tetrazolium based (MTT) assay was used for these lines, to estimate cell growth after gamma irradiation. Control experiments were conducted on lymphoblastoid cell lines (LCL) and the adherent MCC line, MCC13, to demonstrate that the two assays were comparable under the conditions used.

RESULTS

We have examined cell lines from MCC, small cell lung cancer (SCLC), malignant melanomas, Epstein Barr virus (EBV) transformed lymphocytes (LCL), and skin fibroblasts for their sensitivity to gamma irradiation using both clonogenic cell survival and MTT assays. The results show that the tumor cell lines have a range of sensitivities, with melanoma being more resistant (surviving fraction at 2 Gy (SF2) 0.57 and 0.56) than the small cell carcinoma lines, MCC (SF2 range 0.21-0.45, mean SF2 0.30, n = 8) and SCLC (SF2 0.31). Fibroblasts were the most sensitive (SF2 0.13-0.20, mean 0.16, n = 5). The MTT assay, when compared to clonogenic assay for the MCC13 adherent line and the LCL, gave comparable results under the conditions used.

CONCLUSION

Both assays gave a range of SF2 values for the MCC cell lines, suggesting that these cancers would give a heterogeneous response in vivo. The results with the two derivative clones of MCC14 (SF2 for MCC14/1 0.38, MCC14/2 0.45) would further suggest that some of them may develop resistance during clonogenic evolution.

Aspiration biopsy cytology of primary cutaneous tumors

Primary cutaneous neoplasms may undergo fine needle aspiration during the workup of patients with suspected metastatic disease. Such aspirates present a wide range of epithelial and nonepithelial proliferations that must be separated from more common metastatic deposits. The majority of primary cutaneous tumors are composed of squamous or basaloid cells that can be confused with metastatic squamous cell carcinoma. In addition, primary cutaneous lymphomas and mesenchymal tumors morphologically overlap their more common systemic or metastatic counterparts in appearance. Both clinical and cytologic features aid in the differentiation of pilomatrixomas, basal cell carcinomas, sebaceous carcinomas, primary squamous cell carcinomas, Merkel cell tumors and epidermal inclusion cysts from metastatic squamous cell carcinomas. The presence of small basaloid cells in an aspiration smear favors the diagnosis of a primary neoplasm, such as pilomatrixoma or basal cell carcinoma. Clinical findings and cell marker studies are important in the cytologic diagnosis of primary cutaneous lymphomas. Complex convolutions in the nuclei of neoplastic lymphoid cells favor a primary cutaneous origin. We report the cytologic features of 94 primary cutaneous tumors seen in a series of 558 aspirates of subcutaneous and cutaneous nodules.