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Background: The phase III KEYNOTE-913 study was conducted to evaluate the efficacy and safety of pembrolizumab as first-line therapy in patients with advanced Merkel cell carcinoma (MCC)., Objective: The aim was to report results from the primary analysis of KEYNOTE-913., Patients and Methods: Patients with recurrent locally advanced or metastatic MCC received pembrolizumab 200 mg intravenously every 3 weeks for up to 35 treatments (~ 2 years). The primary end point was objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors, version 1.1 (RECIST v1.1) by blinded independent central review (BICR). Secondary end points were duration of response (DOR) and progression-free survival (PFS) per RECIST v1.1 by BICR, overall survival (OS), and safety and tolerability., Results: Fifty-five patients were treated with pembrolizumab. The median time from first dose to data cutoff (February 15, 2024) was 50.3 months (range 38.7-59.4). The ORR was 49% (95% confidence interval [CI] 35-63), with 12 complete responses and 15 partial responses. The median DOR was 39.8 months (range 4.8-52.5+), and the 24-month DOR rate was 69%. The median PFS was 9.3 months (95% CI 3-26), and the 24-month PFS rate was 39%. The median OS was 24.3 months (95% CI 12.4 to not reached), and the 24-month OS rate was 51%. Any-grade treatment-related adverse events (AEs) occurred in 38 patients (69%); 13 patients (24%) experienced grade 3-5 AEs. The most common treatment-related AEs were fatigue (n = 12 [22%]), pruritus (n = 12 [22%]), and lipase increase (n = 10 [18%]). One patient died of treatment-related Guillain-Barré syndrome., Conclusions: Pembrolizumab provided durable antitumor activity and promising survival and had a manageable safety profile in patients with recurrent locally advanced or metastatic MCC, supporting its use in this population., Trial Registration: Clinicaltrials.gov, NCT03783078., (© 2024. The Author(s).)

Background: Merkel cell carcinoma (MCC) is a rare and highly aggressive form of skin cancer. However, there is limited research on the clinicopathological features of early-onset MCC (EOMCC) and the differences between EOMCC and late-onset MCC (LOMCC). Our objective was to evaluate the clinicopathological features and cancer-specific survival (CSS) of EOMCC., Methods: Our cohort study analyzed data from the Surveillance, Epidemiology, and End Results (SEER) database from January 1, 2018, to December 31, 2020. Data from 1941 patients who were diagnosed with primary cutaneous MCC were included. We then divided the patients with MCC into two groups: those with EOMCC (526 patients) and those with LOMCC (1415 patients). CSS is used as the primary outcome., Results: The EOMCC group exhibited trends toward advanced tumor progression, an expanded surgical scope, increased lymph node retrieval, intensified radiotherapy, greater utilization of systemic therapy, and a better prognosis. Multivariate analysis revealed that LOMCC (HR 3.305 [2.002-5.456], P < 0.001), advanced T stage (HR 1.430 [1.139-1.797], P = 0.002), advanced N stage (HR 1.522 [1.221-1.897], P < 0.001), M1 stage (HR 2.587 [1.480-4.521], P < 0.001), and radiation (HR 0.586 [0.410-0.837], P = 0.003) were significantly associated with CSS. Among these factors, EOMCC/LOMCC was most strongly associated with CSS, indicating that LOMCC is an independent risk factor for CSS. Interestingly, we found that regional EOMCC and localized or in situ LOMCC had almost completely overlapping survival curves (P log-rank  = 0.620). Additionally, we observed that the TNM staging + age model was a more accurate predictor of CSS among MCC patients than using TNM staging alone., Conclusions: We found that EOMCC has distinct clinicopathological features compared to LOMCC. EOMCC is associated with better CSS. The combination of TNM staging and age was more accurate for predicting patient outcomes than TNM staging alone., (© 2024 the International Society of Dermatology.)

Purpose/objective(s): Merkel cell carcinoma (MCC) radiation treatment has historically consisted of standard 1.8-2 Gy fractions treated daily over 4-6 weeks. Hypofractionated treatment regimens have demonstrated tumor control and toxicity equivalence to standard fractionation regimens for common cutaneous malignancies such as basal cell and squamous cell carcinomas. Herein we report the outcomes of hypofractionated versus standard fractionation radiotherapy for MCC at our institution., Materials/methods: The study involved a retrospective review of MCC patients treated with radiotherapy. Treatment characteristics and patient outcomes, including acute toxicities, disease recurrence and survival data were collected. The cumulative incidence of local and distant failures was estimated, with death as a competing risk., Results: A total of 29 treatment courses for 24 patients were included, of which 13 involved standard fractionation with curative intent, 10 involved hypofractionated radiotherapy with curative intent, and 6 involved single fraction (8 Gy) palliative radiation. Half the patients were treated to a head/neck site. A subset of patients treated adjuvantly with curative intent included 8 standard fractionation and 8 hypofractionated radiotherapy patients. No statistically significant differences in local and/or distant failure or overall survival was observed between the patient groups., Conclusion: Hypofractionated radiotherapy for MCC was associated with similar treatment outcomes relative to standard fractionation. In our limited patient sample, hypofractionated radiation treatment achieved similar results with similar toxicity and fewer treatments. Further analysis of a larger patient population with longer follow up is needed to confirm treatment tolerability and efficacy., (© 2024. The Author(s).)

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine tumor of the skin. Risk factors include extensive sun damage, infection with Merkel cell polyomavirus, and an immunocompromised state. PRAME, also known as preferentially expressed antigen in melanoma, is a cancer-testis antigen recently found to be a useful diagnostic tool in the workup of melanocytic neoplasms. However, the expression pattern of PRAME in Merkel cell carcinoma is unknown. In this study, we examine PRAME expression in Merkel cell carcinoma and explore its prognostic implications. The institutional archives at the University of Virginia were used to search for tumors classified as Merkel cell carcinoma from 2004 to 2022. All potential cases were reviewed to confirm the diagnosis, and electronic medical records were searched for clinical and demographic data. Tumors were subsequently immunostained for PRAME and Merkel cell polyomavirus. Cox proportional hazards regression models were used to estimate relative (all-cause) survival of PRAME positivity and MCPyV positivity in our study as well as MCC-specific survival of PRAME positivity. Univariate and multivariable models were created for each outcome related to all-cause survival. A total of 39 cases were included in the study. Twenty-eight percent (11 cases) demonstrated strong PRAME expression, and 27% of cases were positive for Merkel cell polyomavirus. There was no statistically significant correlation between PRAME expression and virus positivity. With respect to PRAME, the adjusted all-cause mortality hazard ratio was 11.4 (95% CI: 1.8, 70.8). The unadjusted MCC-specific hazard ratio was 4.6 (95% CI: 0.8, 27.5). The adjusted hazard ratio pertaining to Merkel cell polyomavirus infection was 0.25 (95% CI: 0.02, 2.96). In this limited cohort, PRAME expression appears to correlate with worse outcomes in Merkel cell carcinoma., Competing Interests: Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Competing Interests: Conflicts of interest None disclosed.

Tumor-stroma ratio (TSR) has been recognized as a valuable prognostic indicator in various solid tumors. This study aimed to examine the clinicopathologic relevance of TSR in Merkel cell carcinoma (MCC) using artificial intelligence (AI)-based parameterization of the stromal landscape and validate TSR scores generated by our AI model against those assessed by humans. One hundred twelve MCC cases with whole-slide images were collected from 4 different institutions. Whole-slide images were first partitioned into 128 × 128-pixel "mini-patches," then classified using a novel framework, termed pre-tumor and stroma (Pre-TOAST) and TOAST, whose output equaled the probability of the minipatch representing tumor cells rather than stroma. Hierarchical random samplings of 50 minipatches per region were performed throughout 50 regions per slide. TSR and tumor-stroma landscape (TSL) parameters were estimated using the maximum-likelihood algorithm. Receiver operating characteristic curves showed that the area under the curve value of Pre-TOAST in discriminating classes of interest including tumor cells, collagenous stroma, and lymphocytes from nonclasses of interest including hemorrhage, space, and necrosis was 1.00. The area under the curve value of TOAST in differentiating tumor cells from related stroma was 0.93. MCC stroma was categorized into TSR high (TSR ≥ 50%) and TSR low (TSR < 50%) using both AI- and human pathology-based methods. The AI-based TSR-high subgroup exhibited notably shorter metastasis-free survival (MFS) with a statistical significance of P = .029. Interestingly, pathologist-determined TSR subgroups lacked statistical significance in recurrence-free survival, MFS, and overall survival (P > .05). Density-based spatial clustering of applications with noise analysis identified the following 2 distinct TSL clusters: TSL1 and TSL2. TSL2 showed significantly shorter recurrence-free survival (P = .045) and markedly reduced MFS (P < .001) compared with TSL1. TSL classification appears to offer better prognostic discrimination than traditional TSR evaluation in MCC. TSL can be reliably calculated using an AI-based classification framework and predict various prognostic features of MCC., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Aim: Avelumab has been approved worldwide for treatment of metastatic Merkel cell carcinoma (mMCC), a rare and aggressive skin cancer. This study evaluated outcomes in patients with mMCC in France who received avelumab as second-line or later (2L+) treatment in routine clinical practice., Methods: This retrospective, noninterventional study evaluated all patients diagnosed with mMCC using two databases: CARADERM (French national database of rare dermatological cancers) and SNDS (national healthcare database), identified via probabilistic linkage. Eligible patients initiated avelumab as 2L+ treatment between August 2016 and December 2019 and were followed for 24 months. The primary endpoint was overall survival (OS) at 24 months., Results: Overall, 180 patients who received 2L+ avelumab were identified (112 from CARADERM, 68 after SNDS linkage). Median age at diagnosis was 74.0 years and 177 (98.3 %) had received chemotherapy alone as first-line treatment. Median follow-up was 13.1 months. Median OS from start of avelumab was 14.6 months (95 % CI, 9.9-21.3) in the overall population, 15.9 months (95 % CI, 8.6-28.3) in CARADERM patients, and 13.3 months (95 % CI, 6.7-19.1) in non-CARADERM patients. OS rates at 12 and 24 months were 53.8 % (95 % CI, 46.2 %-60.8 %) and 40.5 % (95 % CI, 33.2 %-47.6 %), respectively. In evaluable patients (CARADERM database), median progression-free survival was 3.6 months (95 % CI, 2.7-7.5) and the objective response rate was 55.3 % (95 % CI, 45.3-65.4), including complete response in 31.9 %., Conclusions: Real-world outcomes with 2L+ avelumab treatment for mMCC are consistent with clinical trial findings, supporting the recommendation of avelumab as a standard of care., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objective: Previous research has primarily focused on the incidence and mortality rates of Merkel cell carcinoma (MCC), neglecting the examination of cardiovascular mortality (CVM) risk among survivors, particularly older patients. This study aims to assess the risk of CVM in older individuals diagnosed with MCC., Methods: Data pertaining to older MCC patients were obtained from the Surveillance, Epidemiology, and End Results database (SEER). CVM risk was measured using standardized mortality ratio (SMR) and cumulative mortality. Multivariate Fine-Gray's competing risk model was utilized to evaluate the risk factors contributing to CVM., Results: Among the study population of 2,899 MCC patients, 465 (16.0%) experienced CVM during the follow-up period. With the prolongation of the follow-up duration, the cumulative mortality rate for CVM reached 27.36%, indicating that cardiovascular disease (CVD) became the second most common cause of death. MCC patients exhibited a higher CVM risk compared to the general population (SMR: 1.69; 95% CI: 1.54-1.86, p < 0.05). Notably, the SMR for other diseases of arteries, arterioles, and capillaries displayed the most significant elevation (SMR: 2.69; 95% CI: 1.16-5.29, p < 0.05). Furthermore, age at diagnosis and disease stage were identified as primary risk factors for CVM, whereas undergoing chemotherapy or radiation demonstrated a protective effect., Conclusion: This study emphasizes the significance of CVM as a competing cause of death in older individuals with MCC. MCC patients face a heightened risk of CVM compared to the general population. It is crucial to prioritize cardiovascular health starting from the time of diagnosis and implement personalized CVD monitoring and supportive interventions for MCC patients at high risk. These measures are essential for enhancing survival outcomes., (© 2024. The Author(s).)

Background: Merkel cell carcinoma (MCC) is an aggressive cancer with often poor outcomes. Limited biomarkers exist for predicting clinical outcomes. The Merkel cell polyomavirus (MCPyV) serum antibody test (AMERK) has shown potential for indicating better recurrence-free survival in a single-institution study. The study aimed to evaluate the link between initial AMERK serostatus and survival. Secondary objectives included examining the relationship between initial AMERK titer levels and tumor burden., Methods: A retrospective cohort study across two institutions analyzed patients tested with AMERK within 90 days of MCC diagnosis. Regression models assessed the association of survival outcomes with serostatus, considering various factors. The relationship between AMERK titer and tumor burden indicators was evaluated using ANOVA. Significance testing was exploratory, without a fixed significance level., Results: Of 261 MCC patients tested, 49.4% were initially seropositive (titer ≥75). Multivariable analysis showed that seropositivity improved recurrence, event-free, overall, and MCC-specific survival rates. Strong associations were found between initial AMERK titer and clinical, tumor, and nodal stages, tumor size, and disease extent. Notably, improved survival with seropositivity was observed only in patients with localized disease at initial presentation., Conclusion: Circulating antibodies to MCPyV oncoproteins, as indicated by the AMERK test, are linked with better survival in MCC patients with localized disease at presentation. This could enhance patient risk profiling and treatment personalization. The study's retrospective nature and exploratory analysis are key limitations., Plain Language Summary: Merkel cell carcinoma (MCC) is a potentially aggressive skin cancer, and tools to predict patient outcomes are limited. A blood test called anti-Merkel cell panel (AMERK), which checks for specific antibodies related to this cancer, might give us some clues. In this study, we looked at 261 MCC patients who took the AMERK test within 90 days of diagnosis. We found that patients with an initial positive AMERK result tended to have better outcomes, especially if their cancer was in the early stages. However, it is important to note that this study has limitations, including using retrospective data and exploratory analyses., (© 2024 American Cancer Society.)

Objectives: Immune checkpoint inhibitors are a promising new therapy for advanced Merkel Cell Carcinoma (MCC). We investigated real-world utilization and survival outcomes of first-line immunotherapies in a contemporary cohort., Methods: Using the National Cancer Database (NCDB), we identified 759 patients with MCC between 2015 and 2020 with stage IV disease and known status of first-line systemic therapy. Univariable and multivariable analyses were used to determine predictors of immunotherapy usage. Overall survival (OS) was compared for patients receiving immunotherapy, chemotherapy, or no systemic therapies., Results: We identified 759 patients meeting our inclusion criteria: 329 patients received immunotherapy, 161 received chemotherapy, and 269 received no systemic therapy. Adjusting for demographic, clinical, and facility factors, high facility volume significantly predicted first-line immunotherapy use (OR 1.99; P =0.017). Median OS was 16.2, 12.3, and 8.7 months, among patients who received immunotherapy, chemotherapy, or no systemic therapy, respectively ( P <0.001). On Cox multivariable survival analysis, first-line immunotherapy treatment (HR=0.79, P =0.041) and treatment at high-volume centers (HR=0.58, P =0.004) were associated with improved OS., Conclusions: Consistent with clinical trial results, first-line immunotherapy associated with improvement in median overall survival for patients with stage IV MCC, significantly outperforming chemotherapy in this real-world cohort. Treatment at high-volume centers associated with first-line immunotherapy utilization suggesting that familiarity with this rare disease is important to achieving optimal outcomes for metastatic MCC., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Objectives: To evaluate the therapeutic effect of post-operative radiotherapy (PORT) with respect to nodal status among patients with head and neck Merkel cell carcinoma (HNMCC)., Methods: In this retrospective study, we queried Surveillance, Epidemiology, and End Results (SEER) dataset from 2000 through 2019. We included all adult patients who received primary surgical resection for histologically confirmed treatment naive HNMCC. Entropy balancing was used to reweight observations such that there was covariate balance between patients who received PORT and patients who received surgical resection alone. Doubly robust estimation was achieved by incorporating weights into a multivariable cox proportional hazards model. Planned post hoc subgroup analysis was performed to evaluate the impact of PORT by pathological node status., Results: Among 752 patients (mean age, 73.3 years [SD 10.8]; 64.2% male; 91.2% White; 41.9% node-positive), 60.4% received PORT. Among node-positive patients, we found that PORT was associated with improved overall survival (OS) (aHR, 0.55; 95% CI, 0.37-0.81; p = 0.003) and improved disease-specific survival (DSS) (aHR, 0.57; 95% CI, 0.35-0.92; p = 0.022). Among node-negative patients, we found that PORT was not associated with OS and was associated with worse DSS (aHR, 2.34; 95% CI, 1.30-4.23; p = 0.005)., Conclusions: We found that PORT was associated with improved OS and DSS for node-positive patients and worse DSS for node-negative patients. For HNMCC treated with primary surgical resection, these data confirm the value of PORT for pathologically node-positive patients and support the use of single modality surgical therapy for pathologically node-negative patients without other adverse risk factors., Level of Evidence: 4 Laryngoscope, 134:3587-3594, 2024., (© 2024 The American Laryngological, Rhinological and Otological Society, Inc.)

Merkel Cell Carcinoma is a rare and aggressive cutaneous carcinoma with a propensity for metastasis and death. Our study describes the prevalence, sociodemographics and inpatient mortality of Merkel Cell Carcinoma related hospitalizations in the United States from 2011 to 2020. We conducted an observational study using the Nationwide Inpatient Sample database, which captures a 20% sample of all hospitalizations in the United States. We utilized the International Classification of Disease Clinical Modification codes from the ninth and tenth revision to identify Merkel Cell Carcinoma and demographic factors. There was a total of 28,809 cases of Merkel Cell Carcinoma in the United States from 2011 to 2020. Merkel Cell Carcinoma was associated with white race (11.4 per 100,000) and disposition of death (26.8 per 100,000). It was most prevalent in the highest quartile income (12.5 per 100,000) and Medicare as primary payer (13.0 per 100,000). Hospitalization was lowest in nonwhite races, particularly NH-Blacks and NH-Others. Inpatient mortality was significantly associated with NH-Others (odds ratio 2.18, 95% confidence interval = 1.38-3.45) and self-pay patients (odds ratio = 2.93, 95% confidence interval 1.84-4.67).This study contributes to reported socio-demographic factors related to Merkel Cell Carcinomas and brings awareness to factors associated with increased hospitalization and inpatient mortality., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Merkel cell carcinoma (MCC) is associated with high rates of recurrence and distant metastatic progression. Current guidelines for surveillance imaging are not evidence based. Better characterization of the pattern of distant metastatic spread will better inform surveillance and facilitate earlier detection of metastases., Objectives: This retrospective study aimed to assess potential relationships between primary tumour site and site of initial distant metastasis, time to distant metastasis, overall survival (OS) and MCC-specific death (MSD)., Methods: Patients with local or regional (Stage I-III) disease who were treated with curative intent and progressed to Stage IV were included in this study (n = 151). Fisher's exact test was used to assess differences in patterns of initial distant metastases based on primary tumour site. Time to initial distant metastasis was calculated from date of MCC diagnosis. OS and MSD were calculated from date of initial distant metastasis to date of death from any or MCC-related causes, respectively., Results: Of 151 patients included in analysis, 89 (58.9%) had a single initial distant metastatic site, and 62 (41.1%) had multiple sites. Patients with upper limb primary tumours were significantly less likely to develop distant lymph node or liver metastases (p = 0.02 and 0.04, respectively). Median time to distant metastasis was 11 months (IQR 6.7-17.9 months). Median OS was 15.3 months, and was shorter for patients with liver (7.0 months, p = 0.0004) or bone metastases (8.9 months, p < 0.0001). Using skin/soft tissue metastasis as a reference group, patients with multiple metastatic sites had significantly higher hazards of MSD (HR = 3.46 univariate, 3.77 multivariate analysis). Time to distant metastasis, OS and MSD did not differ by viral status., Conclusion: Sites of initial distant metastasis are related to primary tumour sites and survival outcomes. Because patients often have multiple initial metastases, full-body cross-sectional rather than region-specific imaging may facilitate earlier detection of metastatic disease., (© 2024 European Academy of Dermatology and Venereology.)

Purpose: Merkel cell carcinoma of the eyelid (MCCE) is a rare yet aggressive neuroendocrine tumour associated with significant morbidity and mortality. This study aimed to investigate survival trends and demographic factors related to MCCE, 2000-2019, using the Surveillance, Epidemiology, and End Results (SEER) Program., Methods: Cases were analysed by demographic parameters, disease properties, and survival. Statistical analyses were performed via a dedicated computerized software package., Results: A total 349 cases of MCCE were identified, accounting for 2% of all MCC cases in the United States during that time. Of note, the incidence of MCCE remained stable over the study period ( p  = .35). Female patients accounted for 56% of the cases, and males for 44%. White patients accounted for 90.8% of the the cases, and Black patients for 2.9%. MCCE incidence increased with age, with the majority of patients age 85+ ( p  < .05). Incidence was greatest in metropolitan areas and among those with median incomes >$75,000/year. Income correlated with likelihood of MCCE diagnosis ( p  < .05). Analysis of 5-year survival data showed 20% of the patients died due to MCCE within 5 years of diagnosis. Of these, the majority died within one year of diagnosis., Conclusions: Consistent with previous reports, most patients were white, female, and age 85+.Incidence correlated with metropolitan environments and median income. While most patients did not die from MCCE, majority of recorded deaths occurred within one year of diagnosis.

Background: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer that most commonly occurs in ultraviolet-exposed body sites. The epidemiology of MCC in different geographies and populations is not well characterized., Objectives: The objective of this systematic review is to summarize evidence on the incidence, mortality and survival rates of MCC from population-based studies., Methods: We searched MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from database inception to 6 June 2023. No geographic, age or date exclusions were applied. We included population-based studies of MCC that reported the incidence, survival or mortality rate, and also considered systematic reviews. A data-charting form was created and validated to identify variables to extract. Two reviewers then independently charted the data for each included study with patient characteristics, and estimates of incidence rate, mortality rate, and survival rate and assessed the quality of included studies using the Joanna Briggs Institute Checklist for Prevalence studies, Newcastle-Ottawa Scale and Assessment of Multiple Systematic Reviews. We abstracted age-, sex-, stage- and race-stratified outcomes, and synthesized comparisons between strata narratively and using vote counting. We assessed the certainty of evidence for those comparisons using the Grading of Recommendations, Assessments, Developments and Evaluations framework., Results: We identified 11 472 citations, of which 52 studies from 24 countries met our inclusion criteria. Stage I and the head and neck were the most frequently reported stage and location at diagnosis. The incidence of MCC is increasing over time (high certainty), with the highest reported incidences reported in southern hemisphere countries [Australia (2.5 per 100 000); New Zealand (0.96 per 100 000) (high certainty)]. Male patients generally had higher incidence rates compared with female patients (high certainty), although there were some variations over time periods. Survival rates varied, with lower survival and/or higher mortality associated with male sex (moderate certainty), higher stage at diagnosis (moderate-to-high certainty), older age (moderate certainty), and immunosuppression (low-to-moderate certainty)., Conclusions: MCC is increasing in incidence and may increase further given the ageing population of many countries. The prognosis of MCC is poor, particularly for male patients, those who are immunosuppressed, and patients diagnosed at higher stages or at an older age., Competing Interests: Conflicts of interest A.M.D. has received compensation from the British Journal of Dermatology (Section Editor), American Academy of Dermatology (guidelines writer), National Eczema Association (grant reviewer) and Canadian Agency for Drugs and Technologies in Health (consultant). A.M.D. has received research grants to his institution from the National Eczema Association, Eczema Society of Canada, Canadian Dermatology Foundation, Canadian Institutes for Health Research, National Institutes of Health and Physicians Services Incorporated Foundation. J.J.L. is a consultant for Feldan Bio, Inc., (© The Author(s) 2023. Published by Oxford University Press on behalf of British Association of Dermatologists.)

Background and Purpose: Clinically localized Merkel cell carcinoma (MCC) has been associated with high rates of disease relapse. This study examines how primary tumor anatomic site drives patterns of care and outcomes in a large cohort treated in the contemporary era., Materials and Methods: Patterns of care and associated outcomes were evaluated for clinically Stage I-II MCC patients treated at our institution with adjuvant radiation therapy (RT) to the primary site and/or regional nodal basin as a component of their curative intent therapy between 2014-2021., Results: Of 80 patients who met inclusion criteria, the primary tumor anatomic site was head and neck (HN) for 42 (53%) and non-head and neck (NHN) for 38 (47%). Primary tumor risk factors were similar between cohorts. Fewer patients with HN tumors had wide local excision (WLE; HN-81% vs. NHN-100% p < 0.01). Of those undergoing WLE, patients with HN tumors received higher dose adjuvant RT (>50 Gy: HN-70% vs. NHN-8%; p < 0.01). Patients with HN tumors were less likely to undergo sentinel lymph node biopsy (HN-62%vs. NHN-100%; p < 0.01) and more likely to have elective nodal RT (HN-48% vs. NHN-0%). Despite varying management strategies, there was no significant difference in local recurrence-free survival (3-yr LRFS HN-94% vs. NHN-94%; p = 0.97), nodal recurrence-free survival (3-yr NRFS HN-89% vs. NHN-85%; p = 0.71) or overall recurrence-free survival (3-yr RFS 73% HN vs. 80% NHN; p = 0.44)., Conclusions: Among patients with primary MCC who had RT as a component of their initial treatment strategy, anatomically-driven heterogeneous treatment approaches were associated with equally excellent locoregional disease control., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Merkel cell carcinoma (MCC) is a rare primary cutaneous neuroendocrine tumour. While dermally invasive MCC is known to have a five-year survival of only 30-40%, the prognosis and management of MCC in situ (MCCis) is not widely reported., Objective: We present a systematic review to elucidate the prognosis and management of MCCis., Methods: We performed a systematic review, searching three databases to 01 June 2021. Case reports, cohort studies, clinical trials and literature reviews were considered for inclusion., Results: We identified 26 cases of MCCis published in the literature with a median age of 74 years and involving 19 males and 7 females. Most cases were on the face and neck (n = 17), followed by upper limb (n = 8) and lower limb (n = 1). Sentinel lymph node biopsy was performed in three patients, and all were negative. One subject underwent adjuvant radiotherapy. No MCCis-associated deaths were reported., Conclusion: This review suggests that MCCis has an excellent prognosis with minimal, if any, risk of mortality and a very low risk of dermal invasion and recurrence when treated with wide local excision alone. Sentinel lymph node biopsy is unlikely to be useful for MCCis., (© 2021 The Australasian College of Dermatologists.)

Background: Bibliometric studies provide a quantitative statistical analysis of the published literature within a field of interest and allow for easy identification of the major contributing authors, funding sources, and publication trends within the field. To date, no bibliometric studies have been performed pertaining to Merkel cell carcinoma (MCC)., Objective: To identify the 100 most frequently cited articles in MCC through a bibliometric analysis of the literature., Methods: Web of science was queried to determine the 100 most frequently cited MCC publications published between the years 1970 and 2019. Articles were listed by title, authors and their affiliated institutions, journal title and type, year of publication, country of origin, funding sources, and citation frequency., Results: Among the 100 most frequently cited MCC publications, articles were cited between 67 and 589 times with a mean of 136.3 times. Articles were cited between 2.0 and 98.2 times per year since publication with a mean of 11.3 times per year. 67% of the articles were published in oncology journals; 33% and 10% of the articles in dermatology and surgery journals, respectively. The most represented journal was Cancer (12%). Paul Nghiem was the most frequently identified author (18%). 36% of the top 100 articles were published out of the University of Washington. The most frequent funding agency was the National Institutes of Health (77%)., Conclusion: Through this bibliometric analysis, researchers can easily identify key publications pertaining to MCC, which may in turn enhance their approach to understanding and practicing evidence-based medicine regarding MCC., (Copyright © 2021 by the American Society for Dermatologic Surgery, Inc. Published by Wolters Kluwer Health, Inc. All rights reserved.)

Objective: To investigate whether surgery improves prognosis in elderly patients with Merkel cell carcinoma (MCC)., Materials/methods: Data of all patients with MCC diagnosed between 2004 and 2015 were extracted from the Surveillance, Epidemiology, and End Results (SEER) database. Differences in baseline characteristics were analyzed among the age groups (75-80, 80-85, and ≥85 years). Multivariate Cox proportional hazards analysis was used to assess the effects of each variable on patient outcomes. The Kaplan-Meier curves were employed to evaluate MCC overall survival (OS) and MCC-specific survival (MSS)., Results: A total of 1156 of patients with MCC met the inclusion and exclusion criteria. The surgery rate decreased with age (75-80, 80-85, and ≥85 years were 93.3%, 91.1%, and 88.7%, respectively; p = 0.082). Multivariate Cox proportional hazards analysis showed that the OS of patients in the 80-85 years group (hazard ratio [HR] = 1.39; 95% confidence interval [CI] = 1.14-1.70; p = 0.001) and the ≥85 years group (HR = 2.18; 95% CI = 1.80-2.63; p < 0.0001) was worse than that in the 75-80 years group. Compared with the non-surgery groups, the HR for the surgery group was 0.75 for OS (95% CI = 0.56-1.00; p = 0.048) and 0.73 for MSS (95% CI = 0.48-1.10; p = 0.130). Subgroup analyses showed that patients aged ≥85 years undergoing surgery had better OS (HR = 0.65; 95% CI = 0.45-0.95; p = 0.024)., Conclusions: MCC patients aged 75 years and older would benefit from surgical resection. However, surgical resection should be performed cautiously, and larger prospective clinical trials are needed to further verify these findings., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Based on its viral-associated or UV-associated carcinogenesis, Merkel cell carcinoma (MCC) is a highly immunogenic skin cancer. Thus, clinically evident MCC occurs either in immuno-compromised patients or based on tumor-intrinsic immune escape mechanisms. This notion may explain that although advanced MCC can be effectively restrained by treatment with PD-1/PD-L1 immune checkpoint inhibitors (ICIs), a considerable percentage of patients does not benefit from ICI therapy. Biomarkers predicting ICI treatment response are currently not available., Methods: The present multicenter retrospective study investigated clinical and molecular characteristics in 114 patients with unresectable MCC at baseline before treatment with ICI for their association with therapy response (best overall response, BOR). In a subset of 21 patients, pretreatment tumor tissue was analyzed for activation, differentiation and spatial distribution of tumor infiltrating lymphocytes (TIL)., Results: Of the 114 patients, n=74 (65%) achieved disease control (BOR=complete response/partial response/stable disease) on ICI. A Bayesian cumulative ordinal regression model revealed absence of immunosuppression and a limited number of tumor-involved organ systems was highly associated with a favorable therapy response. Unimpaired overall performance status, high age, normal serum lactate dehydrogenase and normal serum C reactive protein were moderately associated with disease control. While neither tumor Merkel cell polyomavirus nor tumor PD-L1 status showed a correlation with therapy response, treatment with anti-PD-1 antibodies was associated with a higher probability of disease control than treatment with anti-PD-L1 antibodies. Multiplexed immunohistochemistry demonstrated the predominance of CD8 + effector and central memory T cells (T CM ) in close proximity to tumor cells in patients with a favorable therapy response., Conclusions: Our findings indicate the absence of immunosuppression, a limited number of tumor-affected organs, and a predominance of CD8 + T CM among TIL, as baseline parameters associated with a favorable response to PD-1/PD-L1 ICI therapy of advanced MCC. These factors should be considered when making treatment decisions in MCC patients., Competing Interests: Competing interests: SU declares research support from Bristol Myers Squibb and Merck Serono; speakers and advisory board honoraria from Bristol Myers Squibb, Merck Sharp & Dohme, Merck Serono, Novartis and Roche, and travel support from Bristol Myers Squibb, and Merck Sharp & Dohme. LZ served as consultant and/or has received honoraria from Roche, Bristol-Myers Squibb, Merck Sharp & Dohme, Novartis, Pierre-Fabre, and Sanofi; Research funding to institution: Novartis; travel support from Merck Sharp & Dohme, Bristol-Myers Squibb, Amgen, Pierre-Fabre, and Novartis, outside the submitted work. PT declares invited speaker's honoraria from Bristol-Myers Squibb, Novartis, MSD, Pierre-Fabre, CureVac, Roche, Kyowa Kirin, Biofrontera, advisory board honoraria from Bristol-Myers Squibb, Novartis, Pierre-Fabre, Merck Serono, Sanofi, Roche, Kyowa Kirin, and travel support from Bristol-Myers Squibb, and Pierre-Fabre. UL declares advisory board honoraria from MSD, Roche, Sanofi, Novartis, Sun Pharma, Almirall Hermal. TE declares consulting fees from BMS, Novartis, Roche, Pierre Fabre, Sanofi; board membership and payment for lectures in speakers bureau from Pierre Fabre, MSD, Roche, BMS, Novartis and Sanofi. CL reports advisory board honoraria from MSD, BMS, Roche, Pierre Fabre, Novartis, Sun Pharma, Sanofi, Kyowa Kirin, Almiral Hermal, Biontech, Merc; speakers fee from MSD, BMS, Roche, Pierre Fabre, Novartis, Sun Pharma, Sanofi, Merck; travel reimbusment from MSD, BMS, Roche, Pierre Fabre, Novartis, Sun Pharma, Sanofi, Kyowa Kirin, Almiral Hermal, Biontech and Merck. JCH declares research support from Bristol Myers Squibb; advisory board honoraria from Pierre Fabre, Sanofi, Sun Pharma and Merck Sharp & Dome; speakers honoraria from Bristol Myers Squibb, Merck Sharp & Dohme, Novartis, Roche, Sanofi and Almirall and travel support from Pierre Fabre. TG reports receiving speakers and/or advisory board honoraria from BMS, Sanofi-Grenzyme, MSD, Novartis Pharma, Roche, Abbvie, Almirall, Janssen Lilly, Pfizer, Pierre Fabre; speakers and/or advisory board honoraria from BMS, Sanofi-Grenzyme, MSD, Novartis, Pharma, Roche, Abbvie, Almirall, Janssen Lillly, Pfizer, Pierre Fabre. SH declares advisory boards honoraria from Pierre Fabre, MSD, BMS, Novartis, Sanofi. PM reports board membership and payment for lectures in speakers bureau from Pierre Fabre, GSK, MSD, Merck Germany, Roche, BMS, Novartis, Sanofi. P. Mohr reports research support (to institution): Bristol-MyersSquibb, Novartis, MSD. Honoraria for lectures (personally): Pierre Fabre, GSK, MSD, Merck Germany, Roche, BMS, Novartis, Sanofi, Amgen, SUN-Pharma, Roche Pharma, Bristol-MyersSquibb, Novartis, MSD, Almirall-Hermal, Amgen, Merck-Serono, Bayer, Pierre-Fabre, Sanofi. Honoraria for advisory boards: Pierre Fabre, GSK, MSD, Merck Germany, Roche, BMS, Novartis, Sanofi, Beiersdorf, Almiral-Hermal, AmgenBayersdorf, Roche Pharma, Bristol-MyersSquibb, Novartis, MSD, Almirall-Hermal, Amgen, Pierre-Fabre, Merck-Serono, SUN-Pharma, SUN, Merck-Serono, Sanofi. CP received honoraria (speaker honoraria or honoraria as a consultant) and travel support from Novartis, BMS, Roche, Merck Serono, MSD, Celgene, AbbVie, AMGEN, SUNPHARMA, Allergy Therapeutics and LEO. LMH served as consultant and/or has received honoraria from Amgen, BMS, Curevac, MSD, Novartis, Pierre-Fabre, Roche, Sanofi and Sun Pharma, outside the submitted work. Research funding to institution: Novartis. R. Gutzmer reports research support from Pfizer, Johnson & Johnson, Novartis, Amgen, MerckSerono, SUN Pharma; honoraria for lectures from Roche Pharma, Bristol-MyersSquibb, Novartis, MSD, Almirall-Hermal, Amgen, Merck-Serono, SUN, Pierre-Fabre, Sanofi, SUN Pharma, Bayer; honoraria for advice from Roche Pharma, Bristol-MyersSquibb, Novartis, MSD, Almirall-Hermal, Amgen, Pierre-Fabre, Merck-Serono, 4SC, Incyte, SUN Pharma, Sanofi, Pfizer. JSU is on the advisory board or has received honoraria and travel support from Amgen, Bristol Myers Squibb, GSK, LeoPharma, Merck Sharp and Dohme, Novartis, Pierre Fabre, Roche, Sanofi outside the submitted work. H-US is an employee of Targos Molecular Pathology Inc. and reports research support from Novartis Oncology and received honoraria from MSD, BMS, Roche Pharma, Novartis Oncology, AstraZeneca, Eisai, Takeda, Molecular Health, outside of the submitted work. DS reports personal fees from Amgen, GSK, BMS, Novartis, Roche, Merck, Astra Zeneca, Merck-Serono, Pfizer, Incyte, Array Pierre Fabre, Sanofi Genzyme, Regeneron, 4Sc, InFlaRx, Neracare, Ultimovacs, SunPharma, Philogen, Immunocore, Sandoz-Hexal outside the submitted work. JCB is receiving speaker's bureau honoraria from Amgen, Pfizer, MerckSerono, Recordati and Sanofi; is a paid consultant/advisory board member/DSMB member for Almirall, Boehringer Ingelheim, InProTher, ICON, MerckSerono, Pfizer, 4SC, and Sanofi/Regeneron. His group receives research grants from Bristol-Myers Squibb, Merck Serono, HTG, IQVIA, and Alcedis., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine malignancy of the skin. The cell of origin of MCC is thus far unknown and proposed cells of origin include Merkel cells, pro-/pre- or pre-B cells, epithelial stem cells, and dermal stem cells. In this study, we aimed to shed further light on the possibility that a subset of MCC tumors arise from epithelial stem cells of the skin by examining the expression of hair follicle and epidermal stem cell markers in MCC and normal human skin. We also aimed to elucidate any correlation between the expression of these markers and tumor Merkel cell polyomavirus (MCPyV) status or other clinicopathological characteristics or patient survival. Expression of CK19, SOX9, LGR5, and LRIG1 in MCC and normal human skin was studied by immunohistochemistry, and the staining patterns or intensities were statistically correlated with patient, tumor, MCPyV, and survival parameters. In a cohort of 137 cases of MCC, we observed dot-like immunoexpression of CK19 in 30 cases (22.1%) and homogeneous expression in 103 cases (75.7%). We also observed positive immunoexpression of SOX9 in 21 cases (15.3%), LGR5 in 118 cases (86.1%), and LRIG1 in 117 cases (86.0%). Immunoexpression of LRIG1 was found to correlate with better overall and MCC-specific survival. We observed frequent immunoexpression of several hair follicle and epidermal stem cell markers in MCC and found LRIG1 to be a positive prognostic marker in MCC., (© 2021. The Author(s).)

Aim: There is a need to evaluate current treatments for stages I-III of Merkel cell carcinoma (MCC). Materials & methods: A systematic literature review was conducted to understand how patients with stage I-III MCC are treated and assess efficacy, safety, health-related quality of life and economic impact of current therapies. Embase was searched using the following inclusion criteria: publications from 2014 to 2019, in English, with adult patients (≥18 years) with early-stage MCC (i.e., stages I-III) and any interventions/comparators. Publications were excluded if they included only patients with stage IV MCC, had no distinction between early and advanced or metastatic MCC or had no extractable data. Results:  A total of 18 retrospective studies were included. Few studies had evidence that surgery plus adjuvant radiotherapy significantly increased survival versus surgery alone in early MCC. Limited safety data were reported in three studies. None of the studies reported data on health-related quality of life or economic impact of treatment in patients with early-stage MCC. Conclusion: Although surgery plus adjuvant radiotherapy was a common treatment, no clear standard of care exists for stages I-III MCC and treatment outcomes need to be improved. All studies were retrospective with a high variability in sample sizes; hence, findings should be interpreted with caution.

Background: Merkel cell carcinoma (MCC) is a rare but highly aggressive neuroendocrine carcinoma of the skin. In this study, we aimed to evaluate the clinicopathologic characteristics, treatment outcomes, and survival of MCC cases in Turkey., Materials and Methods: The patients diagnosed with MCC between 1999 and 2018 at twenty different centers in Turkey were included in the study. Patient and tumor characteristics and adjuvant and metastatis treatment outcomes were analyzed retrospectively., Results: The median age of totally 89 patients was 70 (26-93). The most common primary location was lower limbs (n = 29, 32.5%). Immunohistochemically, CK20 positivity was present in 59 patients (66.3%). Only two patients had secondary malignancy. The majority of the patients (n = 76, 85.4%) were diagnosed at the localized stage. Surgery was performed for all patients in the early stage, and adjuvant radiotherapy or/and chemotherapy was applied to 52.6% (n = 40) of nonmetastatic patients. The median follow-up was 29 months. Recurrence developed in 21 (27.6%) of the 76 patients who presented with local or regional disease. Two-year disease-free survival (DFS) was 68.1% and 5-year DFS was 62.0% for localized stage. The 5-year DFS was similar for patients receiving adjuvant treatment (chemotherapy, radiotherapy, or sequential chemoradiotherapy) and without adjuvant therapy (P > 0.05). Two-year overall survival in patients who presented with localized disease was 71.3% and 18.5% in metastatic patients (P < 0.001). In the metastatic stage, platinum/etoposide combination was the most preferred combination regimen. Median progression-free survival (PFS) in first-line chemotherapy was 7 months (95% confidence interval: 3.5-10.5 months; standart error: 1.78)., Conclusions: Although MCC is rare in Turkey, the incidence is increasing. Gender, CK20 status, tumor size, lymph node involvement, and adjuvant treatment were not associated with recurrence., Competing Interests: None

Background: Postoperative radiation therapy (RT) for early-stage Merkel Cell Carcinoma (MCC) decreases the risk of locoregional recurrence and improve overall survival. However, concordance with RT guidelines is unknown., Materials and Methods: The National Cancer Database was queried for stage I/II MCC patients receiving surgical intervention from 2006-2017. The cohort was stratified by patients who had and did not have indication(s) for adjuvant RT of the primary tumor site based on National Comprehensive Cancer Network guidelines. We captured the use of RT, patient demographics, socioeconomic characteristics, and clinical characteristics. Logistic regression, Kaplan-Meier method, and propensity score weighted Cox proportional hazards model examined associations and survival benefits of RT., Results: 2,330 stage I/II MCC patients underwent surgical intervention. 1,858 (79.7%) met National Comprehensive Cancer Network criteria for RT of the primary tumor site, of which 1,062 (57.2%) received RT. 472 (20.3%) did not meet criteria for RT, of which 203 (43.0%) received RT. Five-year overall survival advantage was identified for patients who received RT when it was indicated (P < 0.003). There was no evidence of overall survival advantage when patients received guideline-discordant RT (P = 0.478)., Conclusions: Surgical resection with adjuvant RT of the primary tumor site has an overall survival benefit for local MCC when patients meet criteria for RT. This study found a group who received guideline-discordant RT with no survival advantage. Further investigation is warranted to identify the socio-demographic and oncologic reasons for guideline discordance in the treatment of MCC for both under- and over-treatment., (Copyright © 2021. Published by Elsevier Inc.)

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., (© 2021. The Author(s).)

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.

Merkel cell carcinomas (MCC) are immunogenic skin cancers associated with viral infection or UV mutagenesis. To study T-cell infiltrates in MCC, we analyzed 58 MCC lesions from 39 patients using multiplex-IHC/immunofluorescence (m-IHC/IF). CD4 + or CD8 + T cells comprised the majority of infiltrating T lymphocytes in most tumors. However, almost half of the tumors harbored prominent CD4/CD8 double-negative (DN) T-cell infiltrates (>20% DN T cells), and in 12% of cases, DN T cells represented the majority of T cells. Flow cytometric analysis of single-cell suspensions from fresh tumors identified DN T cells as predominantly Vδ2 - γδ T cells. In the context of γδ T-cell inflammation, these cells expressed PD-1 and LAG3, which is consistent with a suppressed or exhausted phenotype, and CD103, which indicates tissue residency. Furthermore, single-cell RNA sequencing (scRNA-seq) identified a transcriptional profile of γδ T cells suggestive of proinflammatory potential. T-cell receptor (TCR) analysis confirmed clonal expansion of Vδ1 and Vδ3 clonotypes, and functional studies using cloned γδ TCRs demonstrated restriction of these for CD1c and MR1 antigen-presenting molecules. On the basis of a 13-gene γδ T-cell signature derived from scRNA-seq analysis, gene-set enrichment on bulk RNA-seq data showed a positive correlation between enrichment scores and DN T-cell infiltrates. An improved disease-specific survival was evident for patients with high enrichment scores, and complete responses to anti-PD-1/PD-L1 treatment were observed in three of four cases with high enrichment scores. Thus, γδ T-cell infiltration may serve as a prognostic biomarker and should be explored for therapeutic interventions. See related Spotlight on p. 600 ., (©2021 American Association for Cancer Research.)

Merkel cell carcinoma (MCC) is a rare skin cancer with only limited therapeutic options for advanced disease. We previously showed that oncogene ALK is frequently expressed at the RNA level in MCC and further that ALK positivity by immunohistochemistry is frequent and correlates strongly with Merkel cell polyomavirus (MCPyV) positivity. In this study, we investigated whether ALK receptor is active in MCC tumor samples and MCC cell lines, and whether ALK would be a prospective treatment target in MCC. We utilized tissue microarrays constructed from 136 primary MCC tumor samples as well as nine previously established MCC cell lines to determine the presence of ALK and phosphorylated ALK (p-ALK) via immunohistochemistry. Almost half of the analyzed MCC tumors displayed ALK phosphorylation (47.8%). Analysis of MCC tumor samples revealed that the presence of p-ALK correlated to MCPyV positivity, younger age, nonexistence of metastases at diagnosis and ultimately to better MCC-specific survival. In contrast to MCC tumor samples only two out of nine MCC cell lines showed only low ALK phosphorylation by immunohistochemistry. Our study reveals clear disparity in ALK activity between patient derived tumors and cell line samples and therefore, more advanced disease models such as xenografts are necessary to resolve whether ALK is a useful treatment target in MCC., Competing Interests: The authors have declared that no competing interests exist.

The association of immune markers and clinicopathologic features and patient outcome has not been extensively studied in Merkel cell carcinoma (MCC). We correlated tumoral PD-L1 and IDO1 expression, and intratumoral CD8+ and FoxP3+ lymphocytes count with clinicopathologic variables, Merkel cell polyomavirus (MCPyV) status, and patient outcomes in a series of 132 MCC. By univariate analyses, tumoral PD-L1 expression >1% and combined tumoral PD-L1 >1% and high intratumoral FoxP3+ lymphocyte count correlated with improved overall survival (OS) ( p = 0.016, 0.0072), MCC-specific survival (MSS) ( p = 0.019, 0.017), and progression-free survival (PFS) ( p = 0.043, 0.004, respectively). High intratumoral CD8+ and FoxP3+ lymphocyte count correlated with longer MSS ( p = 0.036) and improved PFS ( p = 0.047), respectively. Ulceration correlated with worse OS and worse MSS. Age, male gender, and higher stage (3 and 4) significantly correlated with worse survival. MCPyV positivity correlated with immune response. By multivariate analyses, only ulceration and age remained as independent predictors of worse OS; gender and stage remained for shorter PFS. Tumoral PD-L1 expression and increased density of intratumoral CD8+ lymphocytes and FoxP+ lymphocytes may represent favorable prognosticators in a subset of MCCs. Tumoral PD-L1 expression correlated with intratumoral CD8+ and FoxP3+ lymphocytes, which is supportive of an adaptive immune response.

Purpose: Early stage Merkel cell carcinoma (MCC) is a rare and aggressive primary skin cancer. The standard of care for MCC is broad excision and adjuvant external beam radiation therapy (EBRT). However, for some patients, anesthesia is contraindicated, while others run the risk of serious aesthetic sequelae. In such cases, exclusive radiotherapy is an interesting alternative to surgery. Though limited data is available, this study evaluates exclusive radiotherapy for MCC, using data from the largest retrospective study to date., Methods: All patients who were followed in our center between 1989 and 2019 for histologically proven early stage MCC were included in the study. They were treated either by surgery with a 2-cm clear margin followed by adjuvant radiotherapy (RT) or by exclusive RT. Survival rates with adjuvant and exclusive EBRT were analyzed using Cox model and Fine and Gray model depending on the type of survival. p value < 0.05 was considered significant., Results: Eighty-four patients treated for MCC were included. Fifty-three of them (63.1%) were treated by exclusive RT, and 31 (36.9%) had surgical excision followed by adjuvant RT. Local relapse rate was 13.7% (95% CI 8.0-43.7) in the RT monotherapy group (group A) and 25.8% (95% CI 10.3-56.2) in the surgery + RT group (group B) (p = 0.42). No statistical difference was found for nodal relapse (p = 0.81), metastatic relapse (p = 0.10), disease free survival (p = 0.83) or overall survival (p = 0.98)., Conclusion: Our study suggests that exclusive radiotherapy for early Merkel cell carcinoma leads to a similar oncological outcome as combined treatment, with fewer aesthetic sequelae. The approach is interesting for elderly patients with comorbidities or patients for whom surgery would cause significant functional or aesthetic sequelae.

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., (©2021 American Association for Cancer Research.)

Importance: Current recommendations regarding the size of local excision (LE) margins for Merkel cell carcinoma (MCC) have not been well established., Objective: To assess whether larger clinical LE margins and receipt of adjuvant radiotherapy are associated with improvements in overall survival (OS) among patients with localized MCC., Design, Setting, and Participants: This large multicenter retrospective cohort study used records from the National Cancer Database to identify adult patients with localized stage I or stage II MCC who underwent LE between January 1, 2004, and December 31, 2015. Data were analyzed from August 1, 2020, to January 25, 2021., Exposures: Local excision margin size and adjuvant radiotherapy., Main Outcomes and Measures: Overall and net survival were assessed using Cox multivariable regression analysis., Results: A total of 6156 patients with localized MCC (median age at diagnosis, 77 years [range, 27-90 years]; 2500 women [40.6%]). In the multivariable regression analysis, LE clinical margins larger than 1.0 cm were associated with improvements in OS (HR, 0.88; 95% CI, 0.81-0.95; P < .001) compared with margins of 1.0 cm or smaller, regardless of tumor subsite. At 5 years after surgery, LE margins of 1.0 cm or smaller were associated with a net survival of 76.7%, while LE margins larger than 1.0 cm were associated with a net survival of 89.8% (P < .001). Stratification of LE margins into 3 subgroups indicated that LE margins of 1.1 to 2.0 cm (HR, 0.87; 95% CI, 0.76-0.99; P = .047) and larger than 2.0 cm (HR, 0.84; 95% CI, 0.72-0.98; P = .03) were associated with improvements in OS compared with margins of 1.0 cm or smaller. In patients with less aggressive disease (ie, those who were immunocompetent and had tumors ≤1.0 cm, no lymphovascular invasion, and negative pathologic margins), LE margins larger than 1.0 cm were also associated with improvements in OS (HR, 0.87; 95% CI, 0.78-0.97; P = .01). Among patients who received adjuvant radiotherapy, larger LE margins were associated with improvements in OS (HR, 0.87; 95% CI, 0.76-0.98; P = .03). Receipt of adjuvant radiotherapy was also associated with improvements in OS within the 3 LE margin subgroups. Patients who received adjuvant radiotherapy and had LE margins of 1.0 cm or smaller (HR, 0.81; 95% CI, 0.74-0.89; P < .001) experienced OS that was comparable to that in patients who did not receive adjuvant radiotherapy and had LE margins larger than 1.0 cm (HR, 0.80; 95% CI, 0.71-0.89; P = .87)., Conclusions and Relevance: In this study, LE clinical margins larger than 1.0 cm were associated with improvements in OS, and these improvements were independent of tumor subsite, receipt of adjuvant radiotherapy, positive pathologic margins, or adverse pathologic features for stage I to stage II MCC. Patients with LE margins of 1.0 cm or smaller who received adjuvant radiotherapy experienced OS that was similar to that of patients with larger LE margins who did not receive radiotherapy. The combination of LE clinical margins larger than 1.0 cm and adjuvant radiotherapy was associated with the highest OS.

Background: Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine tumor that primarily affects elderly patients. Despite aggressive treatment, overall survival (OS) remains low., Methods: This study is a multi-institutional, retrospective review of 102 patients with MCC. We evaluated OS, disease-specific survival (DSS), and risk factors for recurrence., Results: Median age of patients was 71.46% of patients recurred. Patients with stage I disease had median 5-year OS of 59.3%, compared to 68.1% DSS. For stage III, median 5-year OS was 46.0% vs 58.2% DSS. Disease stage and advanced age were risk factors for recurrence and decreased OS. Immunocompromised status and disease stage were the strongest predictors of DSS., Conclusions: DSS is significantly better than OS for patients with MCC. Many elderly patients with newly diagnosed MCC have low remaining life expectancy, regardless of their MCC diagnosis. Patient age and overall health status should be considered to personalize care plans for patients with MCC., (Published by Elsevier Inc.)

Background: Wide local excision constitutes the standard of care for Merkel cell carcinoma, but the optimal margin width remains controversial., Objectives: To assess whether narrow margins (0.5-1 cm) were associated with outcome., Methods: Patients were recruited from a retrospective French multicentric cohort and included if they had had excision of primary tumor with minimum lateral margins of 0.5 cm. Factors associated with mortality and recurrence were assessed by multivariate regression., Results: Among the 214 patients included, 58 (27.1%) had undergone excision with narrow margins (0.5-1 cm) versus 156 (72.9%) with wide margins (>1 cm). During a median follow-up of 50.7 months, cancer-specific survival did not differ between groups (5-year specific survival rate 76.8% [95% confidence interval 61.7%-91.9%] and 76.2% [95% confidence interval 68.8%-83.6%], respectively). Overall survival, any recurrence-free survival, and local recurrence-free survival did not significantly differ between groups. Cancer-specific mortality was associated with age, male sex, American Joint Committee on Cancer stage III, and presence of positive margins., Limitations: Retrospective design, heterogenous baseline characteristics between groups., Conclusion: Excision with narrow margins was not associated with outcome in this cohort, in which most patients had clear margins and postoperative radiation therapy. Residual tumor, mostly found on deep surgical margins, was independently associated with prognosis., Competing Interests: Conflicts of interest Dr Dreno reports personal fees from Board Merck Pfizer, outside the submitted work. Dr Saiag reports personal fees from Novartis, Pierre Fabre, BMS, MSD, Merk Serono, and Pfizer; and grants from Pierre Fabre and MSD outside the submitted work. Drs Jaouen, Kervarrec, Caille, Le Corre, Esteve, Wierzbiecka-Hainault, Maillard, Dinulescu, Blom, and Samimi have no conflicts of interest to declare., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

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.

Background: Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with poor survival. Programmed cell death-1 (PD-1) pathway inhibitors have shown high rates of durable tumor regression compared with chemotherapy for MCC. The current study was undertaken to assess baseline and on-treatment factors associated with MCC regression and 3-year survival, and to explore the effects of salvage therapies in patients experiencing initial non-response or tumor progression after response or stable disease following first-line pembrolizumab therapy on Cancer Immunotherapy Trials Network-09/KEYNOTE-017., Methods: In this multicenter phase II trial, 50 patients with advanced unresectable MCC received pembrolizumab 2 mg/kg every 3 weeks for ≤2 years. Patients were followed for a median of 31.8 months., Results: Overall response rate to pembrolizumab was 58% (complete response 30%+partial response 28%; 95% CI 43.2 to 71.8). Among 29 responders, the median response duration was not reached (NR) at 3 years (range 1.0+ to 51.8+ months). Median progression-free survival (PFS) was 16.8 months (95% CI 4.6 to 43.4) and the 3-year PFS was 39.1%. Median OS was NR; the 3-year OS was 59.4% for all patients and 89.5% for responders. Baseline Eastern Cooperative Oncology Group performance status of 0, greater per cent tumor reduction, completion of 2 years of treatment and low neutrophil-to-lymphocyte ratio were associated with response and longer survival. Among patients with initial disease progression or those who developed progression after response or stable disease, some had extended survival with subsequent treatments including chemotherapies and immunotherapies., Conclusions: This study represents the longest available follow-up from any first-line anti-programmed death-(ligand) 1 (anti-PD-(L)1) therapy in MCC, confirming durable PFS and OS in a proportion of patients. After initial tumor progression or relapse following response, some patients receiving salvage therapies survived. Improving the management of anti-PD-(L)1-refractory MCC remains a challenge and a high priority., Trial Registration Number: NCT02267603., Competing Interests: Competing interests: PN reports grants from Bristol-Myers Squibb and EMD-Serono; advisory fees from EMD-Serono, Pfizer and Merck & Co.; travel expenses from Sanofi/Regeneron and Merck & Co. and has a pending patent related to high-affinity T-cell receptors that target the Merkel polyomavirus. SB reports personal fees from Bristol-Myers Squibb, EMD-Serono and personal fees and other from Sanofi-Genzyme; grants from Bristol-Myers Squibb, EMD-Serono, Merck & Co., NantKwest, Novartis, Immune Design, Oncosec, Exicure, Nektar; and personal fees from Castle Biosciences. EJ reports grants from Merck & Co., Bristol-Myers Squibb and Sanofi/Regeneron; personal fees from Bristol-Myers Squibb, Novartis, Array BioPharma, Macrogenics, Sanofi/Regeneron and Genentech. RK reports grants from Merck & Co., Bristol-Myers Squibb and Regeneron; advisory fees from Merck & Co., Bristol-Myers Squibb, Regeneron, Novartis and Array. ASB reports personal fees from Bayer, Deciphera and EMD Serono. BAH reports grants from Merck & Co., Tempest Therapeutics, Olatec Therapeutics, A*STAR Singapore, Sanofi, Leap Therapeutics, GSK and AstraZeneca; personal fees from Merck & Co., Novartis, G1 Therapeutics and CE Concepts; travel fees from ASCO and ASCI and patents related to dendritic cell vaccines, immunotherapy biomarkers and methods for augmenting anti-PD-1 therapy. CC reports a pending patent related to high-affinity T-cell receptors that target the Merkel polyomavirus. JT reports consulting/advisory fees from Merck & Co, Bristol-Myers Squibb, AstraZeneca and Compugen; and a grant from Bristol-Myers Squibb. EJ, MK and BHM are employees of Merck & Co. SPF reports research funding from Merck. MAC reports research funding from Merck & Co. SLT reports that she or an immediate family member has stock and other ownership interests in Aduro Biotech, DNAtrix, Dracen Pharmaceuticals, Dragonfly Therapeutics, Ervaxx, Five Prime Therapeutics, Potenza Therapeutics, RAPT, Tizona Therapeutics, Trieza Therapeutics and WindMIL; a consulting or advisory role in Amgen, DNAtrix, Dragonfly Therapeutics, Dynavax, Ervaxx, Five Prime Therapeutics, Immunocore, Immunomic Therapeutics, Janssen Pharmaceuticals, MedImmune/AstraZeneca, Merck & Co., RAPT and WindMIL; research grants from Bristol-Myers Squibb and Compugen; patents, royalties and/or other intellectual property with Aduro Biotech, Arbor Pharmaceuticals, Bristol-Myers Squibb, Immunomic Therapeutics, NexImmune and WindMIL and travel, accommodations, and expenses from Bristol-Myers Squibb, Dragonfly and Five Prime Therapeutics., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: There is no article that studies whether the regional lymph node (RLN) status affects the prognosis of Merkel cell carcinoma (MCC)., Methods: The survival and disease data of MCC patients were obtained from the Surveillance, Epidemiological, and End Results (SEER) database. The overall survival (OS) and cause-specific survival (CSS) rates were endpoints., Results: A total of 1822 patients were included, with a mean age of 72.5 years. The number of RLN-positive patients was 862 (47.3%), and the number of RLN-negative patients was 960 (52.7%). The regression analysis showed that primary site, sex, and tumor size were statistically significant and independent predictors of RLN status. The five-year OS and CSS of RLN-negative patients were 71.4% and 92.3%, respectively, which were much higher than those of RLN-positive patients (37.5% and 65.8%, respectively) (P <0.001). In univariate survival analysis, positive RLN significantly predicted deterioration of OS and MSS (P <0.001). In multivariate analysis, RLN status had no statistically significant effect on patient prognosis., Conclusion: The prognosis of patients with RLN metastasis is worse than that of patients without RLN metastasis, but RLN status is not an independent predictor of the prognosis of patients with MCC., Competing Interests: Declaration of Competing Interest All the authors declare they have no conflict of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Objective: Prognostic factors and optimal treatment approaches for Merkel cell carcinoma (MCC) remain uncertain. This study evaluated the influences of sentinel lymph node (SLN) biopsy and lymphovascular invasion (LVI) on treatment planning and prognosis., Study Design: Retrospective cohort study., Methods: Stage 1 to 3 MCC patients treated 2005 to 2018. Predictors of nodal radiation were tested using logistic regression. Predictors of recurrence-free, disease-specific, and overall survival were tested in Cox proportional hazard models., Results: Of 122 patients, 99 were without clinically apparent nodal metastases. Of these, 76 (77%) underwent excision and SLN biopsy; 29% had metastasis in SLNs, including 20% of MCCs 1 cm or less. Primary tumor diameter, site, patient age, gender, and immunosuppressed status were not significantly associated with an involved SLN. Among patients who underwent SLN biopsy, 13 of 21 (62%) MCCs with LVI had cancer in SLNs compared with 14 of 44 (25.5%) without LVI (P = .003). Although local radiation was common, nodal radiation was infrequently employed in SLN negative (pathologic N0) patients (21.8% vs. 76.2% for patients with SLN metastases, P = .0001). Survival of patients with positive SLNs was unfavorable, regardless of completion lymphadenectomy and/or adjuvant radiation. After accounting for tumor (T) and node (N) classification, age, immunosuppression, and primary site, a positive SLN and LVI were independently associated with worse survival (LVI/recurrence-free survival [RFS]: hazard ratio [HR] 2.3 (1.04-5, P = .04; LVI/disease-specific survival [DSS]: HR 5.2 (1.8-15, P = .007); N1a vs. pN0/RFS HR 3.6 (1.42-9.3, P = .007); DSS HR5.0 (1.3-19, P = .17)., Conclusion: SLN biopsy assists in risk stratification and radiation treatment planning in MCC. LVI and disease in SLNs, independently associated with worse survival, constitute markers of high-risk disease warranting consideration for investigational studies., Level of Evidence: III Laryngoscope, 131:E828-E835, 2021., (© 2020 The American Laryngological, Rhinological and Otological Society, Inc.)

Competing Interests: Conflicts of interest None disclosed.

Background: Studies have observed that women have better outcomes than men in melanoma, but less is known about the influence of sex differences on outcomes for other aggressive cutaneous malignancies., Objective: To investigate whether women and men have disparate outcomes in Merkel cell carcinoma (MCC)., Methods: Patients with nonmetastatic MCC undergoing surgery and lymph node evaluation were identified from the National Cancer Database (NCDB) and the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier analysis and Cox proportional hazards regression models were used for overall survival, and competing-risks analysis and Fine-Gray models were used for cause-specific and other-cause mortality., Results: The NCDB cohort (n = 4178) included 1516 (36%) women. Women had a consistent survival advantage compared with men in propensity score-matched analysis (66.0% vs 56.8% at 5 years, P < .001) and multivariable Cox regression (hazard ratio, 0.68; 95% confidence interval, 0.61-0.75; P < .001). Similarly, women had a survival advantage in the SEER validation cohort (n = 1202) with 457 (38.0%) women, which was entirely due to differences in MCC-specific mortality (5-year cumulative incidence: 16.4% vs 26.7%, P = .002), with no difference in other-cause mortality (16.8% vs 17.8%, P = .43) observed in propensity score-matched patients., Limitations: Potential selection bias from a retrospective data set., Conclusion: In MCC, women have improved survival compared with men, driven by MCC-related mortality., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Current lymph node (LN) staging for Merkel cell carcinoma (MCC) does not account for the number of metastatic LNs, which is a primary driver of survival in multiple cancers., Objective: To determine the impact of the number of metastatic LNs on survival in MCC., Methods: Patients with MCC undergoing surgery were identified from the National Cancer Database (NCDB). The association between metastatic LN number and survival was modeled with restricted cubic splines. A novel nodal classification system was derived by using recursive partitioning analysis. MCC patients undergoing surgery in the Surveillance, Epidemiology, and End Results (SEER) Program were used as validation cohort., Results: Among 3670 patients in the NCDB, increasing metastatic LN number was associated with decreased survival (P < .001). Mortality risk increased continuously with each additional positive LN when using multivariable, nonlinear modeling. According to a novel staging system derived via recursive partitioning analysis, the hazard ratio for death in multivariable regression compared with patients without LN involvement was 1.24 (P = .049), 2.08 (P < .001), 3.24 (P < .001), and 6.13 (P < .001) for the proposed N1a (1-3 metastatic LNs with microscopic detection), N1b (1-3 metastatic LNs with macroscopic detection), N2 (4-8 metastatic LNs), and N3 (≥9 metastatic LNs), respectively. This system was validated in the SEER cohort and showed improved concordance compared with the American Joint Committee on Cancer, Eighth Edition., Limitations: Retrospective design., Conclusions: Number of metastatic LNs is the dominant nodal factor driving survival in patients with MCC., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Background: Merkel cell carcinoma (MCC) management typically includes surgery with or without adjuvant radiation therapy (aRT). Major challenges include determining surgical margin size and whether aRT is indicated., Objective: To assess the association of aRT, surgical margin size, and MCC local recurrence., Methods: Analysis of 188 MCC cases presenting without clinical nodal involvement., Results: aRT-treated patients tended to have higher-risk tumors (larger diameter, positive microscopic margins, immunosuppression) yet had fewer local recurrences (LRs) than patients treated with surgery only (1% vs 15%; P = .001). For patients who underwent surgery alone, 7 of 35 (20%) treated with narrow margins (defined as ≤1.0 cm) developed LR, whereas 0 of 13 patients treated with surgical margins greater than 1.0 cm developed LR (P = .049). For aRT-treated patients, local control was excellent regardless of surgical margin size; only 1% experienced recurrence in each group (1 of 70 with narrow margins ≤1 cm and 1 of 70 with margins >1 cm; P = .56)., Limitations: This was a retrospective study., Conclusions: Among patients treated with aRT, local control was superb even if significant risk factors were present and margins were narrow. We propose an algorithm for managing primary MCC that integrates risk factors and optimizes local control while minimizing morbidity., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Merkel cell carcinomas (MCCs) are rare, aggressive, cutaneous neuroendocrine tumours, approximately 80% of which are caused by the genomic integration of Merkel cell polyomavirus (MCPyV). MCPyV-positive MCCs carry poor prognosis in approximately 70% of cases, highlighting the need for greater understanding of the oncogenic mechanisms involved in pathogenesis, progression and post-therapeutic relapse, and translation into novel therapeutic strategies. In a previous pilot study, we reported a potential relationship between MCPyV gene expression and oncogenic alternative Δ exon 6-7 TrkAIII splicing in formalin-fixed paraffin-embedded (FFPE) MCC tissues from a 12-patient cohort of >90% MCPyV-positive MCCs, diagnosed at San Salvatore Hospital, L'Aquila, Italy, characterising a new MCC subgroup and unveiling a novel potential MCPyV oncogenic mechanism and therapeutic target. This, however, could not be fully verified due to poor RNA quality and difficulty in protein extraction from FFPE tissues. Here, therefore, we extend our previous observations to confirm the relationship between MCPyV and oncogenic alternative Δ exon 6-7 TrkAIII splicing in fresh, nonfixed, MCPyV-positive MCC metastasis by detecting sequence-verified RT-PCR products, including full-length Δ exon 6-7 TrkAIII, and by Western blot detection of a 100 kDa TrkA protein isoform of identical size to 100 kDa Δ exon 6-7 TrkAIII expressed by stable transfected SH-SY5Y cells. We also report that in three MCC patients submitted for multidisciplinary treatment, including locoregional chemotherapy, MCPyV large T-antigen mRNA expression, Δ exon 6-7 TrkAIII mRNA expression and intracellular indirect immunofluorescence (IF) TrkA and phosphorylation protein isoform(s) immunoreactivity in FFPE tissues were not reduced in postchemotherapeutic-relapsed MCCs compared to pretherapeutic MCCs, extending the possible roles of this novel potential MCPyV oncogenic mechanism from MCC pathogenesis to post-therapeutic relapse and progression. Detection of alternative Δ exon 6-7 TrkAIII splicing in MCC, therefore, not only characterises a new MCPyV-positive MCC subgroup and unveils a novel potential MCPyV oncogenic mechanism but also identifies patients who may benefit from inhibitors of MCPyV T-antigen and/or TrkAIII expression or clinically approved Trk kinase inhibitors such as larotrectinib or entrectinib, which are known to inhibit activated TrkA oncogenes and to elicit durable responses in TrkA-fusion oncogene-driven cancers, supporting the call for a large-scale multicentre clinical study.

Purpose: Immunosuppressed (IS) patients are at increased risk for developing Merkel cell carcinoma (MCC) with worsened outcomes compared to immunocompetent (IC) patients. We sought to determine the effects of immune status on the efficacy of adjuvant RT regarding OS for patients with stage I, II or III (localized) MCC of the head and neck., Methods/patients: The National Cancer Database was queried for patients with resected, localized MCC of the head and neck with known immune status. Kaplan-Meier methods were used to describe OS. Log-rank tests, multivariable Cox regression models and interaction effect testing were used to compare OS by subgroup categorized by patient and treatment factors including immune status and adjuvant RT receipt., Results: A total of 892 (89.6%) IC and 104 (10.4%) IS patients with MCC of the head and neck were included. Adjuvant RT was associated with improved 3-year OS rate for both IS patients (49.4% vs. 35.5%, p = 0.0467) and stage I/II IC patients (72.4% vs. 62.9%, p = 0.0092). Adjuvant RT was associated with decreased hazard of death (HR 0.77, 95% CI 0.62-0.95). Interaction effect testing did not demonstrate a difference in the efficacy of adjuvant RT on OS between IC and IS status (p = 0.157)., Conclusions: In this NCDB analysis, adjuvant RT was associated with decreased hazard of death for patients with localized MCC of the head and neck regardless of immune status and should be considered for both IS and IC patients.

The integrity of the immune system represents a pivotal risk factor and prognostic biomarker for Merkel cell carcinoma. A higher density of tumor-associated T cells correlates with improved Merkel cell carcinoma-specific survival, but the prognostic importance of the T-cell infiltrate reactivity is unknown. We evaluated the T-cell receptor repertoire associated with 72 primary Merkel cell carcinomas and correlated metrics of the T-cell receptor repertoire with clinicopathologic characteristics and patient outcomes. We showed that a high Simpson's Dominance index (SDom) was significantly associated with fewer metastases (P = 0.01), lower stage at presentation (P = 0.02), lower final stage at last follow-up (P = 0.05), and longer time to first lymph node metastasis (P = 0.04). These correlations were mostly preserved in the Merkel cell polyomavirus-negative subgroup. Combining SDom with CD3 + or CD8 + T-cell density revealed three distinct prognostic groups with respect to disease-specific survival. Patients with both high SDom and high CD3 + or CD8 + T-cell density had markedly improved disease-specific survival compared with patients with low SDom and low CD3 + or CD8 + T-cell density (P = 0.002 and P = 0.03, respectively). Patients with either high SDom or high CD3 + or CD8 + had intermediate disease-specific survival. Our findings demonstrate that the quality of the tumor-associated T-cell infiltrate informs patient prognosis in primary Merkel cell carcinoma beyond the T-cell density., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)