Efficacy and Safety of First-line Avelumab Treatment in Patients With Stage IV Metastatic Merkel Cell Carcinoma: A Preplanned Interim Analysis of a Clinical Trial

A landscape of checkpoint blockade resistance in cancer: underlying mechanisms and current strategies to overcome resistance

The discovery of immune checkpoints and the development of immune checkpoint inhibitors (ICI) have achieved a durable response in advanced-stage cancer patients. However, there is still a high proportion of patients who do not benefit from ICI therapy due to a lack of response when first treated (primary resistance) or detection of disease progression months after objective response is observed (acquired resistance). Here, we review the current FDA-approved ICI for the treatment of certain solid malignancies, evaluate the contrasting responses to checkpoint blockade in different cancer types, explore the known mechanisms associated with checkpoint blockade resistance (CBR), and assess current strategies in the field that seek to overcome these mechanisms. In order to improve current therapies and develop new ones, the immunotherapy field still has an unmet need in identifying other molecules that act as immune checkpoints, and uncovering other mechanisms that promote CBR.

Merkel cell carcinoma: updates in tumor biology, emerging therapies, and preclinical models

Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma thought to arise via either viral (Merkel cell polyomavirus) or ultraviolet-associated pathways. Surgery and radiotherapy have historically been mainstays of management, and immunotherapy has improved outcomes for advanced disease. However, there remains a lack of effective therapy for those patients who fail to respond to these established approaches, underscoring a critical need to better understand MCC biology for more effective prognosis and treatment. Here, we review the fundamental aspects of MCC biology and the recent advances which have had profound impact on management. The first genetically-engineered mouse models for MCC tumorigenesis provide opportunities to understand the potential MCC cell of origin and may prove useful for preclinical investigation of novel therapeutics. The MCC cell of origin debate has also been advanced by recent observations of MCC arising in association with a clonally related hair follicle tumor or squamous cell carcinoma in situ. These studies also suggested a role for epigenetics in the origin of MCC, highlighting a potential utility for this therapeutic avenue in MCC. These and other therapeutic targets form the basis for a wealth of ongoing clinical trials to improve MCC management. Here, we review these recent advances in the context of the existing literature and implications for future investigations.

Profound ctDNA and radiological responses after 2 cycles of avelumab in a metastatic Merkel cell carcinoma of the head and neck

BACKGROUND

Merkel cell carcinoma (MCC) is an uncommon skin cancer that in more than 90 % of cases develops within the head and neck region. MCC is an aggressive disease with a dismal prognosis before the advent of immunotherapy. Avelumab, an anti-PDL1 agent is approved since 2017 for the treatment of advanced MCC after demonstrating a high response rate and favorable impact in survival.

METHODS

Next generation sequencing (NGS) of the primary tumor biopsy from initial diagnosis (Foundation One CDx, Roche Diagnostics) as well as from plasma samples (Foundation One Liquid, Roche Diagnostics) obtained before and during treatment with avelumab were performed.

RESULTS

We present the case of a patient with a metastatic MCC developing in the left parotid gland / pre-auricular area in an 80-year-old male with a long-lasting history of high UV exposure. After two cycles of avelumab 10 mg/kg/q2wk a near complete metabolic response and a major radiological response occurred in parallel to a brisk reduction in the ctDNA tumor fraction as well as variant-allele frequencies (VAFs) of all the mutations detected before the start of avelumab.

CONCLUSION

Avelumab may achieve rapid and major responses in metastatic MCC. Our study demonstrates that ctDNA mirrors radiological responses and may serve as an ideal companion for diagnosis and disease monitoring in MCC.

Immunotherapy in Neuroendocrine Neoplasms: A Diamond to Cut

A raise in the incidence of NENs is expected. Therefore, the identification of new therapeutic strategies, such as immunotherapy, remains crucial. To date, immune checkpoint inhibitors as monotherapy have shown modest activity in unselected NENs. Although immunotherapy combos (plus another immune agents or chemotherapy, among others) are potentially more active than single agents, this has not been uniformly confirmed, even in high-grade NENs. Other immunotherapeutic strategies under development include bispecific antibodies, targeting specific tumor antigens like DLL3, and cell therapy. Currently, no predictive immune biomarkers are available to guide clinical decisions. A comprehensive tumor molecular profiling approach needs to be developed for the selection of patients with NEN who could potentially benefit from immunotherapy. Ideally, clinical trials should incorporate this tumor molecular profiling to identify predictive biomarkers and improve efficacy. Achieving this goal requires an international collaborative effort.

Lack of Clinically Significant Relationships of Age or Body Mass Index with Merkel Cell Carcinoma Immunotherapy Outcomes

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer with a high risk of metastasis. The development of anti-PD-1/PD-L1 immunotherapy has improved outcomes for advanced MCC, yet about 50% of such patients do not achieve durable responses. This study analyzed the effects of age and body mass index (BMI) on immunotherapy response in 183 advanced MCC patients from a single-center longitudinal database. Using Fine-Gray or Cox regression models, treatment response, progression-free survival (PFS), MCC-specific survival, and overall survival (OS) were evaluated. Age showed a significant non-linear relationship with treatment response (p = 0.04), with patients much older or younger than 70 years less likely to respond. However, age was not significantly associated with PFS (p = 0.21), MCC-specific survival (p = 0.72), or OS (p = 0.36). Similarly, BMI was not significantly correlated with treatment response (p = 0.41), PFS (p = 0.52), MCC-specific survival (p = 0.78), or OS (p = 0.71). Unlike previous studies suggesting that obesity and advanced age improve outcomes in other cancers, these associations were not observed in MCC. These findings suggest that age and BMI should not influence eligibility for immunotherapy in MCC patients, emphasizing the importance of unbiased patient selection for this treatment.

Merkel Cell Carcinoma: Integrating Epidemiology, Immunology, and Therapeutic Updates

Merkel cell carcinoma (MCC) is a rare skin cancer characterized by neuroendocrine differentiation. Its carcinogenesis is based either on the integration of the Merkel cell polyomavirus or on ultraviolet (UV) mutagenesis, both of which lead to high immunogenicity either through the expression of viral proteins or neoantigens. Despite this immunogenicity resulting from viral or UV-associated carcinogenesis, it exhibits highly aggressive behavior. However, owing to the rarity of MCC and the lack of epidemiologic registries with detailed clinical data, there is some uncertainty regarding the spontaneous course of the disease. Historically, advanced MCC patients were treated with conventional cytotoxic chemotherapy yielding a median response duration of only 3 months. Starting in 2017, four programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) immune checkpoint inhibitors-avelumab, pembrolizumab, nivolumab (utilized in both neoadjuvant and adjuvant settings), and retifanlimab-have demonstrated efficacy in treating patients with disseminated MCC on the basis of prospective clinical trials. However, generating clinical evidence for rare cancers, such as MCC, is challenging owing to difficulties in conducting large-scale trials, resulting in small sample sizes and therefore lacking statistical power. Thus, to comprehensively understand the available clinical evidence on various immunotherapy approaches for MCC, we also delve into the epidemiology and immune biology of this cancer. Nevertheless, while randomized studies directly comparing immune checkpoint inhibitors and chemotherapy in MCC are lacking, immunotherapy shows response rates comparable to those previously reported with chemotherapy but with more enduring responses. Notably, adjuvant nivolumab has proven superiority to the standard-of-care therapy (observation) in the adjuvant setting.

High-Risk Non-Melanoma Skin Cancers: Biological and Therapeutic Advances

Nonmelanoma skin cancers (NMSCs) are the most common cancers, with high-risk NMSCs sharing features such as poor histologic differentiation, invasion into deeper layers, and anatomic location. NMSC includes basal cell carcinoma, cutaneous squamous cell carcinoma, and Merkel cell carcinoma. Herein, the authors describe advances in understanding the genetic mechanisms of malignant transformation and the composition of tumor microenvironment for these cancers. They summarize recent therapeutic advances, including targeted therapy and immunotherapy for NMSCs. Effective skin protection against ultraviolet radiation-induced carcinogenesis remains an urgent unmet need for NMSC prevention. The authors highlight immune-based interventions as novel strategies to address this need.

Different prognosis in cutaneous early-onset and late-onset Merkel cell carcinoma: a population-based retrospective study

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 (Plog-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.

Patterns of initial distant metastases in 151 patients undergoing surveillance for treated Merkel cell carcinoma

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.

[Periocular Merkel Cell Carcinoma - an overview of clinical aspects and current therapeutic options]

Merkel cell carcinoma (MCC) is a rare but highly aggressive and rapidly expanding malignant skin tumor. It affects the periocular region in approximately 10% of cases. The current treatment recommendation for resectable non-metastatic MCC comprises total surgical excision; however, lymph node or distant metastases are often already present by the time of the diagnosis. Since an immune checkpoint inhibitor therapy with avelumab was first approved for MCC in 2016, there has been considerable improvement in mean survival compared to cytostatic therapy; at the same time, there has been a reduction in serious treatment-associated adverse events. Other immune checkpoint inhibitors are currently still in clinical trials, with very promising initial results. Because of the complexity of the diagnosis, treatment, and prognosis, it is essential that MCC patients receive interdisciplinary care in a specialized center including consultation with a tumor review board.

Emerging Treatment Options for Neuroendocrine Neoplasms of Unknown Primary Origin: Current Evidence and Future Perspectives

Among neuroendocrine neoplasms (NENs), a non-negligible proportion (9-22%) is represented by sufferers of NENs of unknown primary origin (UPO), a poor prognostic group with largely unmet clinical needs. In the absence of standard therapeutic algorithms, current guidelines suggest that the treatment of UPO-NENs should be based on tumor clinical-pathological characteristics, disease burden, and patient conditions. Chemotherapy represents the backbone for the treatment of high-grade poorly differentiated UPO-NENs, usually providing deep but short-lasting responses. Conversely, the spectrum of available systemic therapy options for well-differentiated UPO-NENs may range from somatostatin analogs in indolent low-grade tumors, to peptide receptor radioligand therapy, tyrosine kinase inhibitors (TKIs), or chemotherapy for more aggressive tumors or in case of high disease burden. In recent years, molecular profiling has provided deep insights into the molecular landscape of UPO-NENs, with both diagnostic and therapeutic implications. Although preliminary, interesting activity data have been provided about upfront chemoimmunotherapy, the use of immune checkpoint inhibitors (ICIs), and the combination of ICIs plus TKIs in this setting. Here, we review the literature from the last 30 years to examine the available evidence about the treatment of UPO-NENs, with a particular focus on future perspectives, including the expanding scenario of targeted agents in this setting.

Regulatory mechanisms of PD-1/PD-L1 in cancers

Immune evasion contributes to cancer growth and progression. Cancer cells have the ability to activate different immune checkpoint pathways that harbor immunosuppressive functions. The programmed death protein 1 (PD-1) and programmed cell death ligands (PD-Ls) are considered to be the major immune checkpoint molecules. The interaction of PD-1 and PD-L1 negatively regulates adaptive immune response mainly by inhibiting the activity of effector T cells while enhancing the function of immunosuppressive regulatory T cells (Tregs), largely contributing to the maintenance of immune homeostasis that prevents dysregulated immunity and harmful immune responses. However, cancer cells exploit the PD-1/PD-L1 axis to cause immune escape in cancer development and progression. Blockade of PD-1/PD-L1 by neutralizing antibodies restores T cells activity and enhances anti-tumor immunity, achieving remarkable success in cancer therapy. Therefore, the regulatory mechanisms of PD-1/PD-L1 in cancers have attracted an increasing attention. This article aims to provide a comprehensive review of the roles of the PD-1/PD-L1 signaling in human autoimmune diseases and cancers. We summarize all aspects of regulatory mechanisms underlying the expression and activity of PD-1 and PD-L1 in cancers, including genetic, epigenetic, post-transcriptional and post-translational regulatory mechanisms. In addition, we further summarize the progress in clinical research on the antitumor effects of targeting PD-1/PD-L1 antibodies alone and in combination with other therapeutic approaches, providing new strategies for finding new tumor markers and developing combined therapeutic approaches.

Merkel Cell Carcinoma Metastases To Caruncle With Orbital Extension: Report and Literature Review

Merkel cell carcinoma (MCC) is an uncommon and aggressive skin cancer of neuroendocrine origin. The tumor usually presents with a locoregional spread and most frequently metastasizes to the skin, liver, bone, lung, and brain. Despite the orbit being a relatively common site of metastases, it has rarely been reported in patients with MCC. The authors present a case of biopsy-proven orbital metastatic MCC in an 86-year-old male who presented with a rapidly enlarging right caruncle/subconjunctival mass with orbital extension and a history of forearm MCC excision 3 years prior. There are only 3 reported cases of distant metastatic MCC to the orbit, all presenting as a mass originating from extraocular muscles; and no cases of caruncle involvement.

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.

Safety and effectiveness of avelumab in patients with Merkel cell carcinoma in general clinical practice in Japan: Post-marketing surveillance

Avelumab, a programmed cell death ligand 1 blocking antibody, was approved for its first indication in Japan in September 2017 to treat unresectable Merkel cell carcinoma (MCC). Given that the pivotal JAVELIN Merkel 200 study only included a few Japanese patients, this post-marketing surveillance (PMS) evaluated the safety and effectiveness outcomes of patients with MCC who received avelumab in general clinical practice in Japan. This prospective, non-comparative, multicenter PMS included data from all patients with unresectable MCC who received avelumab between November 22, 2017 (avelumab launch date) and October 31, 2019. The primary objective was to evaluate avelumab safety (i.e., adverse events [AEs], adverse drug reactions [ADRs], and ADRs of safety specifications). The secondary objective was to evaluate avelumab effectiveness (i.e., objective response rate and overall survival [OS] rate). Seventy-five evaluable patients were included, of whom 81.3% experienced AEs of any grade (57.3% experienced AEs of grade ≥ 3; 41.3% experienced AEs of grade 5) and 61.3% experienced ADRs (14.7% experienced ADRs of grade ≥ 3; no grade 5 ADRs were observed). The most common ADRs were pyrexia (18.7%), infusion related reaction (10.7%), and chills (6.7%). The most common ADRs of safety specifications were infusion reactions (any grade: n = 21 [28.0%]; grade 3 or 4: n = 3 [4.0%]), thyroid dysfunction (n = 7 [9.3%]), and hepatic function disorders (n = 4 [5.3%]). The median observation period was 51 weeks. An objective response was achieved by 34/75 patients (45.3%; complete response, 24.0%; partial response, 21.3%) and 6- and 12-month OS rates were 77.7% and 59.6%, respectively. This PMS confirmed the clinical tolerability and effectiveness of avelumab in patients with MCC, with no new safety concerns. The risk-benefit profile of avelumab was comparable with that observed in clinical trials and remains favorable for use in general clinical practice in Japan.

High-volume facilities are significantly more likely to use guideline-adherent systemic immunotherapy for metastatic Merkel cell carcinoma: implications for cancer care regionalization

Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a high rate of mortality. While still relatively rare, the incidence of MCC has been rapidly rising in the US and around the world. Since 2017, two immunotherapeutic drugs, avelumab and pembrolizumab, have been FDA-approved for the treatment of metastatic MCC and have revolutionized outcomes for MCC. However, real-world outcomes can differ from clinical trial data, and the adoption of novel therapeutics can be gradual. We aimed to characterize the treatment practices and outcomes of patients with metastatic MCC across the US. A retrospective cohort study of adult cases of MCC in the National Cancer Database diagnosed from 2004 to 2019 was performed. Multivariable logistic regressions to determine the association of a variety of patient, tumor, and system factors with likelihood of receipt of systemic therapies were performed. Univariate Kaplan-Meier and multivariable Cox survival regressions were performed. We identified 1017 cases of metastatic MCC. From 2017 to 2019, 54.2% of patients received immunotherapy. This increased from 45.1% in 2017 to 63.0% in 2019. High-volume centers were significantly more likely to use immunotherapy (odds ratio 3.235, p = 0.002). On univariate analysis, patients receiving systemic immunotherapy had significantly improved overall survival (p < 0.001). One-, 3-, and 5-year survival was 47.2% (standard error [SE] 1.8%), 21.8% (SE 1.5%), and 16.5% (SE 1.4%), respectively, for patients who did not receive immunotherapy versus 62.7% (SE 3.5%), 34.4% (SE 3.9%), and 23.6% (SE 4.4%), respectively, for those who did (Fig. 1). In our multivariable survival regression, receipt of immunotherapy was associated with an approximately 35% reduction in hazard of death (hazard ratio 0.665, p < 0.001; 95% CI 0.548-0.808). Our results demonstrate that the real-world survival advantage of immunotherapy for metastatic MCC is similar to clinical trial data. However, many patients with metastatic disease did not receive this guideline-recommended therapy in our most recent study year, and use of immunotherapy is higher at high-volume centers. This suggests that regionalization of care to high-volume centers or dissemination of their practices, may ultimately improve patient survival.

Avelumab to treat Merkel cell carcinoma: real-life experience in a dedicated oncology center

The arrival of immunotherapy has revolutioned the management of patients with metastatic Merkel cell carcinoma (MCC). We conducted an observational, retrospective study of 14 cases treated with avelumab. The response rate was 57%: complete response was reached in 29% of patients, and partial responses in 29%. The drug proved effective in 83% (5/6) of the patients with a single metastatic site. However, the disease progressed in 75% (3/4) of the patients with bone metastases. PD1-L expression, MCC polyomavirus (MCPyV) positivity, and an impaired neutrophil-to-lypmhocyte ratio (NLR) could not be associated with responses to the therapy. Avelumab is an effective and safe drug for the management of advanced MCC, and its effectiveness appears to be impacted by the number and location of metastases.

T antigen-specific CD8+ T cells associate with PD-1 blockade response in virus-positive Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a highly immunogenic skin cancer primarily induced by Merkel cell polyomavirus, which is driven by the expression of the oncogenic T antigens (T-Ags). Blockade of the programmed cell death protein-1 (PD-1) pathway has shown remarkable response rates, but evidence for therapy-associated T-Ag-specific immune response and therapeutic strategies for the nonresponding fraction are both limited. We tracked T-Ag-reactive CD8+ T cells in peripheral blood of 26 MCC patients under anti-PD1 therapy, using DNA-barcoded pMHC multimers, displaying all peptides from the predicted HLA ligandome of the oncoproteins, covering 33 class I haplotypes. We observed a broad T cell recognition of T-Ags, including identification of 20 T-Ag-derived epitopes we believe to be novel. Broadening of the T-Ag recognition profile and increased T cell frequencies during therapy were strongly associated with clinical response and prolonged progression-free survival. T-Ag-specific T cells could be further boosted and expanded directly from peripheral blood using artificial antigen-presenting scaffolds, even in patients with no detectable T-Ag-specific T cells. These T cells provided strong tumor-rejection capacity while retaining a favorable phenotype for adoptive cell transfer. These findings demonstrate that T-Ag-specific T cells are associated with the clinical outcome to PD-1 blockade and that Ag-presenting scaffolds can be used to boost such responses.

An Updated Review of the Biomarkers of Response to Immune Checkpoint Inhibitors in Merkel Cell Carcinoma: Merkel Cell Carcinoma and Immunotherapy

Merkel cell carcinoma (MCC) is primarily a disease of the elderly Caucasian, with most cases occurring in individuals over 50. Immune checkpoint inhibitors (ICI) treatment has shown promising results in MCC patients. Although ~34% of MCC patients are expected to exhibit at least one of the predictive biomarkers (PD-L1, high tumor mutational burden/TMB-H/, and microsatellite instability), their clinical significance in MCC is not fully understood. PD-L1 expression has been variably described in MCC, but its predictive value has not been established yet. Our literature survey indicates conflicting results regarding the predictive value of TMB in ICI therapy for MCC. Avelumab therapy has shown promising results in Merkel cell polyomavirus (MCPyV)-negative MCC patients with TMB-H, while pembrolizumab therapy has shown better response in patients with low TMB. A study evaluating neoadjuvant nivolumab therapy found no significant difference in treatment response between the tumor etiologies and TMB levels. In addition to ICI therapy, other treatments that induce apoptosis, such as milademetan, have demonstrated positive responses in MCPyV-positive MCC, with few somatic mutations and wild-type TP53. This review summarizes current knowledge and discusses emerging and potentially predictive biomarkers for MCC therapy with ICI.

Review of Merkel cell carcinoma with solitary pancreatic metastases mimicking primary neuroendocrine tumor of the pancreas

OBJECTIVE/BACKGROUND

Merkel cell carcinoma (MCC) but metastases to the pancreas are very rare. There are only a few cases of isolated metastases of MCC to the pancreas. Because of this rarity, it can be wrongly diagnosed as a neuroendocrine tumor of the pancreas(pNET), especially the poorly differentiated neuroendocrine carcinoma (PNEC) subtype, in which the treatment is vastly different than that of MCC with isolated metastases of the pancreas.

METHODS

An electronic search of the PubMed and google scholar databases was performed to obtain the literature on MCC with pancreatic metastases, using the following search terms: Merkel cell carcinoma, pancreas, and metastases. Results are limited to the following available article types: case reports and case series. We identified 45 cases of MCC with pancreatic metastases from the PubMed and Google Scholar database search and examined their potential relevance. Only 22 cases with isolated pancreatic metastases were taken for review including one case that we encountered.

RESULTS

The results from our review of cases of isolated pancreatic metastases of MCC were compared to the characteristics of the poorly differentiated pancreatic neuroendocrine tumor (PNEC). We found the following: (a) MCC with isolated pancreatic metastases occurred at an older age than PNEC and with male gender predominance (b) Most of the metastases occurred within 2 years of initial diagnosis of MCC (c) Resection of pancreatic mass was the first line treatment in case of resectable PNECs whereas resection of metastases was infrequently performed in MCC with pancreatic metastases.

Merkel cell carcinoma: an update

Merkel cell carcinoma (MCC) is an uncommon primary cutaneous neuroendocrine carcinoma associated with an adverse prognosis. In recent years, our understanding of MCC biology has markedly progressed. Since the discovery of the Merkel cell polyomavirus, it has become clear that MCC represents an ontogenetically dichotomous group of neoplasms with overlapping histopathology. Specifically, most MCCs arise secondary to viral oncogenesis, while a smaller subset is the direct result of UV-associated mutations. The distinction of these groups bears relevance in their immunohistochemical and molecular characterization, as well as in disease prognosis. Further recent developments relate to the landmark utilization of immunotherapeutics in MCC, providing optimistic options for the management of this aggressive disease. In this review, we discuss both fundamental and emerging concepts in MCC, with a particular focus on topics of practical relevance to the surgical or dermatopathologist.

ExoPD-L1: an assistant for tumor progression and potential diagnostic marker

The proliferation and function of immune cells are often inhibited by the binding of programmed cell-death ligand 1 (PD-L1) to programmed cell-death 1 (PD-1). So far, many studies have shown that this combination poses significant difficulties for cancer treatment. Fortunately, PD-L1/PD-1 blocking therapy has achieved satisfactory results. Exosomes are tiny extracellular vesicle particles with a diameter of 40~160 nm, formed by cells through endocytosis. The exosomes are a natural shelter for many molecules and an important medium for information transmission. The contents of exosomes are composed of DNA, RNA, proteins and lipids etc. They are crucial to antigen presentation, tumor invasion, cell differentiation and migration. In addition to being present on the surface of tumor cells or in soluble form, PD-L1 is carried into the extracellular environment by tumor derived exosomes (TEX). At this time, the exosomes serve as a medium for communication between tumor cells and other cells or tissues and organs. In this review, we will cover the immunosuppressive role of exosomal PD-L1 (ExoPD-L1), ExoPD-L1 regulatory factors and emerging approaches for quantifying and detecting ExoPD-L1. More importantly, we will discuss how targeted ExoPD-L1 and combination therapy can be used to treat cancer more effectively.

The Evolving Treatment Landscape of Merkel Cell Carcinoma

OPINION STATEMENT

Merkel cell carcinoma (MCC) has a high risk of recurrence and requires unique treatment relative to other skin cancers. The patient population is generally older, with comorbidities. Multidisciplinary and personalized care is therefore paramount, based on patient preferences regarding risks and benefits. Positron emission tomography and computed tomography (PET-CT) is the most sensitive staging modality and reveals clinically occult disease in ~ 16% of patients. Discovery of occult disease spread markedly alters management. Newly diagnosed, localized disease is often managed with sentinel lymph node biopsy (SLNB), local excision, primary wound closure, and post-operative radiation therapy (PORT). In contrast, metastatic disease is usually treated systemically with an immune checkpoint inhibitor (ICI). However, one or more of these approaches may not be indicated. Criteria for such exceptions and alternative approaches will be discussed. Because MCC recurs in 40% of patients and early detection/treatment of advanced disease is advantageous, close surveillance is recommended. Given that over 90% of initial recurrences arise within 3 years, surveillance frequency can be rapidly decreased after this high-risk period. Patient-specific assessment of risk is important because recurrence risk varies widely (15 to > 80%: Merkelcell.org/recur) depending on baseline patient characteristics and time since treatment. Blood-based surveillance tests are now available (Merkel cell polyomavirus (MCPyV) antibodies and circulating tumor DNA (ctDNA)) with excellent sensitivity that can spare patients from contrast dye, radioactivity, and travel to a cancer imaging facility. If recurrent disease is locoregional, management with surgery and/or RT is typically indicated. ICIs are now the first line for systemic/advanced MCC, with objective response rates (ORRs) exceeding 50%. Cytotoxic chemotherapy is sometimes used for debulking disease or in patients who cannot tolerate ICI. ICI-refractory disease is the major problem faced by this field. Fortunately, numerous promising therapies are on the horizon to address this clinical need.

Brief Communication: Lambert-Eaton Myasthenic Paraneoplastic Syndrome Associated With Merkel Cell Carcinoma Successfully Treated by Immune Checkpoint Inhibitors: 2 Cases

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine cutaneous tumor with high metastatic potential. In rare cases, it can be associated with paraneoplastic syndromes (PNS), which result from an antitumor immunity against antigens produced by the tumor itself. Lambert-Eaton Myasthenic Syndrome (LEMS) is a neurological autoimmune PNS characterized by an impairment of the neuromuscular junction, leading to proximal muscle weakness and fatigability. Although the development of immune checkpoint inhibitors (ICI) is a breakthrough in the management of many cancers, onset or worsen of immune diseases has been described. Thereby, in patients with previous neurological PNS like LEMS, the ICI therapy for cancer may aggravate neurological symptoms and lead to irreversible impairment. We report here 2 cases of patients with metastatic MCC associated with a LEMS at the diagnosis. Both successfully received ICI therapies (anti-PDL1 avelumab and anti-PD1 pembrolizumab) without worsening of LEMS and any major immune-related adverse effects. Their neurological condition improved and disappeared concomitantly with the efficacy of immunotherapy, and we did not observe relapse of both MCC and LEMS after treatment discontinuation. Finally, we performed a complete review of the literature, which confirmed that ICI treatment could be discussed for patients with paraneoplastic LEMS, and emphasized the need for multidisciplinary management.

Expression of Genes Associated With Epithelial-Mesenchymal Transition in Merkel Cell Polyomavirus-Negative Merkel Cell Carcinoma

Two accepted possible pathways for Merkel cell carcinoma (MCC) pathogenesis include the clonal integration of the Merkel cell polyomavirus (MCPyV) into the neoplastic cells and by UV irradiation. We hypothesize that, in UV etiology, the expression of genes associated with epithelial-mesenchymal transition (EMT) would be higher in MCPyV-negative MCCs. We compared RNA expression in 16 MCPyV-negative with that in 14 MCPyV-positive MCCs in 30 patients using NanoString panel of 760 gene targets as an exploratory method. Subsequently, we confirmed the findings with a publicly available RNA sequencing data set. The NanoString method showed that 29 of 760 genes exhibited significant deregulation. Ten genes (CD44, COL6A3, COL11A1, CXCL8, INHBA, MMP1, NID2, SPP1, THBS1, and THY1) were part of the EMT pathway. The expression of CDH1/E-cadherin, a key EMT gene, and TWIST1, regulator gene of EMT, was higher in MCPyV-negative tumors. To further investigate the expression of EMT genes in MCPyV-negative MCCs, we analyzed publicly available RNA sequencing data of 111 primary MCCs. Differential expression and gene set enrichment analysis of 35 MCPyV-negative versus 76 MCPyV-positive MCCs demonstrated significantly higher expression of EMT-related genes and associated pathways such as Notch signaling, TGF-β signaling, and Hedgehog signaling, and UV response pathway in MCPyV-negative MCCs. The significance of the EMT pathway in MCPyV-negative MCCs was confirmed independently by a coexpression module analysis. One of the modules (M3) was specifically activated in MCPyV-negative MCCs and showed significant enrichment for genes involved in EMT. A network analysis of module M3 revealed that CDH1/E-cadherin was among the most connected genes (hubs). E-cadherin and LEF1 immunostains demonstrated significantly more frequent expression in MCPvV-negative versus MCPyV-positive tumors (P < .0001). In summary, our study showed that the expression of EMT-associated genes is higher in MCPyV-negative MCC. Because EMT-related proteins can be targeted, the identification of EMT pathways in MCPyV-negative MCCs is of potential therapeutic relevance.

Desensitization Protocol for Cemiplimab-Related Infusion Reaction in Cutaneous Squamous Cell Carcinoma: A Case Report and Literature Review

BACKGROUND

The landscape of systemic therapies for advanced non-melanoma skin cancers has been revolutionized by the advent of immunotherapy. Cemiplimab is the only immune checkpoint inhibitor (ICI) approved by the European Medicine Agency for recurrent/metastatic cutaneous squamous cell carcinoma (cSCC). Its excellent efficacy outcomes are achieved due to its good tolerability profile. The drug-related hypersensitivity reaction (HSR) is a well-known issue in oncology, but it is rarely reported in respect to immune checkpoint inhibitors. Cemiplimab is among the agents with the best infusion tolerability profiles. Clinical practice guidelines in this field are lacking.

RESULTS

We report on the successful management of a severe infusion reaction induced by Cemiplimab in a patient with cSCC based on a desensitization protocol, which led to adequate treatment delivery and prolonged clinical benefit. A review of the available literature on HSR rates and its management with ICIs, and on drug desensitization (DD) protocols and their efficacy, was conducted to highlight the limited knowledge on this topic and its importance.

CONCLUSION

Our experience highlights the need for a DD protocol in order to improve the treatment of HSRs, particularly when elicited by an immunotherapy agent, preventing treatment discontinuation and preserving its efficacy.

BRCA1/2 Pathogenic Variants Are Not Common in Merkel Cell Carcinoma: Comprehensive Molecular Study of 30 Cases and Meta-Analysis of the Literature

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous neuroendocrine cancer. Management of advanced MCC is mainly based on immune-checkpoint inhibitors. The high failure rate warrants an investigation of new therapeutic targets. The recent identification of BRCA1 or BRCA2 (BRCA1/2) mutations in some MCC raises the issue of the use of poly-(ADP-Ribose)-polymerase inhibitors in selected advanced cases. The main objective of our study is to determine the accurate frequency of BRCA1/2 pathogenic variants. We studied a series of 30 MCC and performed a meta-analysis of BRCA1/2 variants of published cases in the literature. In our series, we detected only one BRCA2 pathogenic variant. The low frequency of BRCA1/2 pathogenic variants in our series of MCC (3%) was confirmed by the meta-analysis of BRCA1/2 variants in the literature. Among the 915 MCC from 13 published series studied for molecular alterations of BRCA1/2, only 12 BRCA1/2 pathogenic mutations were identified (1-2% of MCC), whereas many other BRCA1/2 variants were variants of unknown significance or benign. BRCA1/2 pathogenic variants are uncommon in MCC. However, in BRCA-mutated MCC, poly-(ADP-Ribose)-polymerase inhibitors might be a valuable therapeutic option requiring validation by clinical trials.

Immune Checkpoint Inhibitors in Solid Organ Transplant Recipients With Advanced Skin Cancers-Emerging Strategies for Clinical Management

Use of immune checkpoint inhibitors (ICIs) in solid organ transplant recipients (SOTRs) with advanced skin cancers presents a significant clinical management dilemma. SOTRs and other immunosuppressed patients have been routinely excluded from ICI clinical trials with good reason: immune checkpoints play an important role in self- and allograft-tolerance and risk of acute allograft rejection reported in retrospective studies affects 10% to 65% of cases. These reports also confirm that cutaneous squamous cell carcinoma and melanoma respond to ICI therapy, although response rates are generally lower than those observed in immunocompetent populations. Prospective trials are now of critical importance in further establishing ICI efficacy and safety. However, based on current knowledge, we recommend that ICIs should be offered to kidney transplant recipients with advanced cutaneous squamous cell carcinoma, melanoma, or Merkel cell carcinoma if surgery and/or radiotherapy have failed. For kidney transplant recipients, this should be first line ahead of chemotherapy and targeted therapies. In SOTRs, the use of ICIs should be carefully considered with the benefits of ICIs versus risks of allograft rejection weighed up on a case-by-case basis as part of shared decision-making with patients. In all cases, parallel management of immunosuppression may be key to ICI responsiveness. We recommend maintaining immunosuppression before ICI initiation with a dual immunosuppressive regimen combining mammalian target of rapamycin inhibitors and either corticosteroids or calcineurin inhibitors. Such modification of immunosuppression must be considered in the context of allograft risk (both rejection and also its subsequent treatment) and risk of tumor progression. Ultimately, a multidisciplinary approach should underpin all clinical decision-making in this challenging scenario.

A Phase II Study of Epacadostat and Pembrolizumab in Patients with Advanced Sarcoma

PURPOSE

Epacadostat, an indole 2,3 dioxygenase 1 (IDO1) inhibitor, proposed to shift the tumor microenvironment toward an immune-stimulated state, showed early promise in melanoma but has not been studied in sarcoma. This study combined epacadostat with pembrolizumab, which has modest activity in select sarcoma subtypes.

PATIENTS AND METHODS

This phase II study enrolled patients with advanced sarcoma into five cohorts including (i) undifferentiated pleomorphic sarcoma (UPS)/myxofibrosarcoma, (ii) liposarcoma (LPS), (iii) leiomyosarcoma (LMS), (iv) vascular sarcoma, including angiosarcoma and epithelioid hemangioendothelioma (EHE), and (v) other subtypes. Patients received epacadostat 100 mg twice daily plus pembrolizumab at 200 mg/dose every 3 weeks. The primary endpoint was best objective response rate (ORR), defined as complete response (CR) and partial response (PR), at 24 weeks by RECIST v.1.1.

RESULTS

Thirty patients were enrolled [60% male; median age 54 years (range, 24-78)]. The best ORR at 24 weeks was 3.3% [PR, n = 1 (leiomyosarcoma); two-sided 95% CI, 0.1%-17.2%]. The median PFS was 7.6 weeks (two-sided 95% CI, 6.9-26.7). Treatment was well tolerated. Grade 3 treatment-related adverse events occurred in 23% (n = 7) of patients. In paired pre- and post-treatment tumor samples, no association was found between treatment and PD-L1 or IDO1 tumor expression or IDO-pathway-related gene expression by RNA sequencing. No significant changes in serum tryptophan or kynurenine levels were observed after baseline.

CONCLUSIONS

Combination epacadostat and pembrolizumab was well tolerated and showed limited antitumor activity in sarcoma. Correlative analyses suggested that inadequate IDO1 inhibition was achieved.

Insights into anti-tumor immunity via the polyomavirus shared across human Merkel cell carcinomas

Understanding and augmenting cancer-specific immunity is impeded by the fact that most tumors are driven by patient-specific mutations that encode unique antigenic epitopes. The shared antigens in virus-driven tumors can help overcome this limitation. Merkel cell carcinoma (MCC) is a particularly interesting tumor immunity model because (1) 80% of cases are driven by Merkel cell polyomavirus (MCPyV) oncoproteins that must be continually expressed for tumor survival; (2) MCPyV oncoproteins are only ~400 amino acids in length and are essentially invariant between tumors; (3) MCPyV-specific T cell responses are robust and strongly linked to patient outcomes; (4) anti-MCPyV antibodies reliably increase with MCC recurrence, forming the basis of a standard clinical surveillance test; and (5) MCC has one of the highest response rates to PD-1 pathway blockade among all solid cancers. Leveraging these well-defined viral oncoproteins, a set of tools that includes over 20 peptide-MHC class I tetramers has been developed to facilitate the study of anti-tumor immunity across MCC patients. Additionally, the highly immunogenic nature of MCPyV oncoproteins forces MCC tumors to develop robust immune evasion mechanisms to survive. Indeed, several immune evasion mechanisms are active in MCC, including transcriptional downregulation of MHC expression by tumor cells and upregulation of inhibitory molecules including PD-L1 and immunosuppressive cytokines. About half of patients with advanced MCC do not persistently benefit from PD-1 pathway blockade. Herein, we (1) summarize the lessons learned from studying the anti-tumor T cell response to virus-positive MCC; (2) review immune evasion mechanisms in MCC; (3) review mechanisms of resistance to immune-based therapies in MCC and other cancers; and (4) discuss how recently developed tools can be used to address open questions in cancer immunotherapy. We believe detailed investigation of this model cancer will provide insight into tumor immunity that will likely also be applicable to more common cancers without shared tumor antigens.

4-[(5-Methyl-1H-pyrazol-3-yl)amino]-2H-phenyl-1-phthalazinone Inhibits MCPyV T Antigen Expression in Merkel Cell Carcinoma Independent of Aurora Kinase A

Merkel cell carcinoma (MCC) is frequently caused by the Merkel cell polyomavirus (MCPyV), and MCPyV-positive tumor cells depend on expression of the virus-encoded T antigens (TA). Here, we identify 4-[(5-methyl-1H-pyrazol-3-yl)amino]-2H-phenyl-1-phthalazinone (PHT)-a reported inhibitor of Aurora kinase A-as a compound inhibiting growth of MCC cells by repressing noncoding control region (NCCR)-controlled TA transcription. Surprisingly, we find that TA repression is not caused by inhibition of Aurora kinase A. However, we demonstrate that β-catenin-a transcription factor repressed by active glycogen synthase kinase 3 (GSK3)-is activated by PHT, suggesting that PHT bears a hitherto unreported inhibitory activity against GSK3, a kinase known to function in promoting TA transcription. Indeed, applying an in vitro kinase assay, we demonstrate that PHT directly targets GSK3. Finally, we demonstrate that PHT exhibits in vivo antitumor activity in an MCC xenograft mouse model, suggesting a potential use in future therapeutic settings for MCC.

Characterization of the Impact of Merkel Cell Polyomavirus-Induced Interferon Signaling on Viral Infection

Merkel cell polyomavirus (MCPyV) has been associated with approximately 80% of Merkel cell carcinoma (MCC), an aggressive and increasingly incident skin cancer. The link between host innate immunity, viral load control, and carcinogenesis has been established but poorly characterized. We previously established the importance of the STING and NF-κB pathways in the host innate immune response to viral infection. In this study, we further discovered that MCPyV infection of human dermal fibroblasts (HDFs) induces the expression of type I and III interferons (IFNs), which in turn stimulate robust expression of IFN-stimulated genes (ISGs). Blocking type I IFN downstream signaling using an IFN-β antibody, JAK inhibitors, and CRISPR knockout of the receptor dramatically repressed MCPyV infection-induced ISG expression but did not significantly restore viral replication activities. These findings suggest that IFN-mediated induction of ISGs in response to MCPyV infection is not crucial to viral control. Instead, we found that type I IFN exerts a more direct effect on MCPyV infection postentry by repressing early viral transcription. We further demonstrated that growth factors normally upregulated in wounded or UV-irradiated human skin can significantly stimulate MCPyV gene expression and replication. Together, these data suggest that in healthy individuals, host antiviral responses, such as IFN production induced by viral activity, may restrict viral propagation to reduce MCPyV burden. Meanwhile, growth factors induced by skin abrasion or UV irradiation may stimulate infected dermal fibroblasts to promote MCPyV propagation. A delicate balance of these mutually antagonizing factors provides a mechanism to support persistent MCPyV infection. IMPORTANCE Merkel cell carcinoma is an aggressive skin cancer that is particularly lethal to immunocompromised individuals. Though rare, MCC incidence has increased significantly in recent years. There are no lasting and effective treatments for metastatic disease, highlighting the need for additional treatment and prevention strategies. By investigating how the host innate immune system interfaces with Merkel cell polyomavirus, the etiological agent of most of these cancers, our studies identified key factors necessary for viral control, as well as conditions that support viral propagation. These studies provide new insights for understanding how the virus balances the effects of the host immune defenses and of growth factor stimulation to achieve persistent infection. Since virus-positive MCC requires the expression of viral oncogenes to survive, our observation that type I IFN can repress viral oncogene transcription indicates that these cytokines could be explored as a viable therapeutic option for treating patients with virus-positive MCC.

Avelumab for the treatment of locally advanced or metastatic Merkel cell carcinoma-A multicenter real-world experience in Israel

BACKGROUND

Merkel cell carcinoma (MCC) is a rare and aggressive malignancy of the skin, affecting predominantly the fair-skinned older population exposed to high levels of ultraviolet light. Immune suppression is considered a significant risk factor. With the recent advances in the field of immunotherapy, the treatment paradigm for advanced MCC, traditionally based on chemotherapy, has largely shifted to anti-PD-L1 and PD-1 agents such as avelumab and pembrolizumab, respectively. However, real-world data remain sparse. The aim of this study was to assess real-world evidence of the effectiveness of avelumab in a diverse group of patients with MCC in Israel.

METHODS

The electronic databases of five university hospitals in Israel were searched for all consecutive patients with MCC treated with at least one dose of avelumab in 2018-2022. Data on baseline, disease-related, treatment-related, and outcome parameters were collected and analyzed.

RESULTS

The cohort included 62 patients of whom 22% were immune-suppressed. The overall response rate to avelumab was 59%. The median progression-free survival was 8.1 months, and the median overall survival, 23.5 months, with no differences between immune-competent and immune-suppressed patients. Treatment was well tolerated; any-grade toxicity developed in 34% of patients, and grade 3-4 toxicity, in 14%.

CONCLUSIONS

Avelumab was found to be effective and safe for the treatment of advanced MCC in a diverse group of patients, including some with immune suppression. Further studies are warranted to evaluate the optimal sequence and duration of treatment and to assess the potential role of avelumab for earlier stages of MCC.

Merkel cell carcinoma: epidemiology, clinical features, diagnosis and treatment of a rare disease

Merkel cell carcinoma is a rare skin cancer with neuroendocrine differentiation. The risk factors include sun exposure, advanced age, immunosuppression (such as transplant recipients, patients with lymphoproliferative neoplasms, or patients with HIV), and Merkel cell polyomavirus infection. Clinically, Merkel cell carcinoma appears as a cutaneous or subcutaneous plaque or nodule, but this tumor diagnosis is rarely made clinically. Therefore, histopathology and immunohistochemistry are usually necessary. Primary tumors without evidence of metastases are treated with complete surgical excision and appropriate surgical margins. The presence of occult metastasis in a lymph node is frequent and a sentinel lymph node biopsy should be performed. Postoperative adjuvant radiotherapy increases local tumor control. Recently, agents that block the PD-1/PD-L1 pathway have shown objective and durable tumor regression in patients with advanced solid malignancies. The first anti-PD-L1 antibody used in patients with Merkel cell carcinoma was avelumab, but pembrolizumab and nivolumab have also shown efficacy. This article describes the current state of knowledge of the epidemiology, diagnosis, and staging of Merkel cell carcinoma, as well as new strategies for its systemic treatment.

Current treatments and emerging therapies of human polyomavirus-associated skin diseases: a comprehensive review

Since Merkel cell polyomavirus (MCPyV) was linked as the predominant etiology of Merkel cell carcinoma (MCC) in 2008, three additional human polyomaviruses (HPyV) have been definitively linked to cutaneous diseases-trichodysplasia spinulosa virus (TSPyV) and human polyomavirus 6 and 7 (HPyV6, HPyV7). TSPyV contributes to the development of trichodysplasia spinulosa (TS), and HPyV6/7 is associated closely with the eruption of pruritic and dyskeratotic dermatoses (PDD). Clinically, MCC is treated with surgical excision and radiation with adjuvant chemotherapy, although newer treatment options include immune checkpoint inhibition. These novel immunotherapies hold promise for the treatment of metastatic MCC, but resistance and side effects prevent a significant proportion of patients from realizing their benefits. Based on previous case reports, the standard of care for the less deadly but disfiguring cutaneous disease TS include immunosuppressant (IS) reduction, the use of antivirals such as cidofovir (CDV) or valganciclovir (VGCV), or a combination of these treatments. Similar treatments were attempted for PDD, but oral acitretin was found to be most effective. As MCC, TS, and PDD are rare diseases, further research is required for effective treatments. In this review, we summarize clinical trials, preclinical studies, and case reports that present outcomes and side effects of current and emerging treatments for HPyV-associated cutaneous diseases, offering a comprehensive resource for clinical application and prospective clinical trials.

Targets of Immune Escape Mechanisms in Cancer: Basis for Development and Evolution of Cancer Immune Checkpoint Inhibitors

Immune checkpoint blockade (ICB) has emerged as a novel therapeutic tool for cancer therapy in the last decade. Unfortunately, a small number of patients benefit from approved immune checkpoint inhibitors (ICIs). Therefore, multiple studies are being conducted to find new ICIs and combination strategies to improve the current ICIs. In this review, we discuss some approved immune checkpoints, such as PD-L1, PD-1, and CTLA-4, and also highlight newer emerging ICIs. For instance, HLA-E, overexpressed by tumor cells, represents an immune-suppressive feature by binding CD94/NKG2A, on NK and T cells. NKG2A blockade recruits CD8+ T cells and activates NK cells to decrease the tumor burden. NKG2D acts as an NK cell activating receptor that can also be a potential ICI. The adenosine A2A and A2B receptors, CD47-SIRPα, TIM-3, LAG-3, TIGIT, and VISTA are targets that also contribute to cancer immunoresistance and have been considered for clinical trials. Their antitumor immunosuppressive functions can be used to develop blocking antibodies. PARPs, mARTs, and B7-H3 are also other potential targets for immunosuppression. Additionally, miRNA, mRNA, and CRISPR-Cas9-mediated immunotherapeutic approaches are being investigated with great interest. Pre-clinical and clinical studies project these targets as potential immunotherapeutic candidates in different cancer types for their robust antitumor modulation.

Prognostic Biomarker SLCO4A1 Is Correlated with Tumor Immune Infiltration in Colon Adenocarcinoma

Background

Solute carrier organic anion transporter family member 4A1 (SLCO4A1), a member of solute carrier organic anion family, is a key gene regulating bile metabolism, organic anion transport, and ABC transport. However, the association of SLCO4A1 with prognosis and tumor immune infiltration in colon adenocarcinoma (COAD) remains indistinct.

Methods

Firstly, we explored the expression level of SLCO4A1 in COAD via GEPIA, Oncomine, and UALCAN databases. Secondly, we used the Kaplan-Meier plotter and PrognoScan databases to investigate the effect of SLCO4A1 on prognosis in COAD patients. In addition, the correlation between SLCO4A1 and tumor immune infiltration was studied by using TIMER and TISIDB databases.

Results

Our results showed that SLCO4A1 was overexpressed in COAD tissues. At the same time, our study showed that high expression of SLCO4A1 was associated with poor overall survival, disease-free survival, and disease-specific survival in COAD patients. The expression level of SLCO4A1 was negatively linked to the infiltrating levels of B cells, CD8+ T cells, and dendritic cells in COAD. Moreover, the expression of SLCO4A1 was significantly correlated with numerous immune markers in COAD.

Conclusions

These results indicated that SLCO4A1 could be associated with the prognosis of COAD patients and the levels of tumor immune infiltration. Our study suggested that SLCO4A1 could be a valuable biomarker for evaluating prognosis and tumor immune infiltration in COAD patients.

Periocular Merkel Cell Carcinoma - An Overview of Clinical Aspects and Current Treatment Options

Merkel cell carcinoma (MCC) is a rare but highly aggressive and rapidly expanding malignant skin tumor. It affects the periocular region in approximately 10% of cases. The current treatment recommendation for resectable non-metastatic MCC comprises total surgical excision; however, lymph node or distant metastases are often already present by the time of the diagnosis. Since an immune checkpoint inhibitor therapy with avelumab was first approved for MCC in 2016, there has been considerable improvement in mean survival compared to cytostatic therapy; at the same time, there has been a reduction in serious treatment-associated adverse events. Other immune checkpoint inhibitors are currently still in clinical trials, with very promising initial results. Because of the complexity of the diagnosis, treatment, and prognosis, it is essential that MCC patients receive interdisciplinary care in a specialized center including consultation with a tumor review board.

Body mass index and baseline platelet count as predictive factors in Merkel cell carcinoma patients treated with avelumab

Background

Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer, associated with a worse prognosis. The Immune Checkpoint Inhibitors (ICIs) avelumab and pembrolizumab have been recently approved as first-line treatment in metastatic MCC (mMCC). The clinical observation of improved outcomes in obese patients following treatment with ICIs, known as the "obesity paradox", has been studied across many types of tumors. Probably due to the rarity of this tumor, data on mMMC patients are lacking.

Patients and methods

This is an observational, hospital-based, study to investigate the role of Body Mass Index (BMI) as predictive biomarker of ICI response in mMCC patients treated with avelumab as first-line treatment. The study population included the patients treated from February 2019 to October 2022 in an Italian referral center for rare tumors. Clinico-pathological characteristics, BMI, laboratory parameters (NLR and platelet count), and response to avelumab were analyzed from a MCC System database prospectively collected.

Results

Thirty-two (32) patients were included. Notably, the presence of pre-treatment BMI ≥ 30 was significantly associated with longer PFS [BMI < 30 Group: median PFS, 4 months (95% CI: 2.5-5.4); BMI ≥ 30 Group: median PFS, not reached; p<0.001)[. Additionally, the median PFS was significantly higher in patients with higher PLT (median PFS: 10 months in the "low PLT" Group (95% CI: 4.9, 16.1) vs 33 months (95% CI: 24.3, 43.2) in the "high PLT" Group (p=0.006). The multivariable Cox regression model confirmed these results.

Conclusion

To our knowledge, this is the first study that investigates the predictive role of BMI in MCC patients. Our data were consistent with the clinical observation of improved outcomes in obese patients across other tumor types. Thus, advanced age, a weakened immune system, and the obesity-associated "inflammaging", are key factors that could impact the cancer immune responses of mMCC patients.

Dietary Considerations for Inflammatory Bowel Disease Are Useful for Treatment of Checkpoint Inhibitor-Induced Colitis

Checkpoint molecules are cell surface receptors on immune cells that mitigate excessive immune responses, but they have increased expression levels in cancer to facilitate immune escape. Checkpoint blockade therapies (e.g., anti-PD-1, anti-CTLA-4, and anti-LAG-3 therapy, among others) have been developed for multiple cancers. Colitis associated with checkpoint blockade therapy has pathophysiological similarities to inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis. Current therapeutic guidelines for checkpoint blockade-induced colitis include corticosteroids and, if the patient is refractory to steroids, immunomodulating antibodies, such as anti-TNF and anti-integrin agents. Interestingly, immunomodulatory molecules, such as TNFα, are upregulated in both IBD and checkpoint-mediated colitis. The inflammatory colitis toxicity symptoms from checkpoint blockade are similar to clinical symptoms experienced by patients with IBD. The pathophysiologic, dietary, and genetic factors associated with IBD will be reviewed. We will then explain how the principles developed for the treatment of IBD can be applied to patients experiencing inflammatory bowel toxicity secondary to checkpoint blockade.

Potential new applications of immunotherapy for neuroendocrine neoplasms: immune landscape, current status and future perspectives

Neuroendocrine neoplasms (NENs) are a highly heterogeneous class of tumors arising from neuroendocrine cells and peptidergic neurons. After failure of first-line treatment, patients have poor prognosis and limited treatment options. Immune checkpoint inhibitors (ICIs) may be a powerful means of increasing therapeutic efficacy for such patients, but ICIs alone have low response rates and short disease control durations in most NENs and may be effective for only a portion of the population. ICIs combined with other immunotherapies, targeted therapies, or cytotoxic drugs have achieved some efficacy in patients with NENs and are worthy of further exploration to assess their benefits to the population. In addition, accumulating experimental and clinical evidence supports that the interaction between neuroendocrine and immune systems is essential to maintain homeostasis, and assessment of this broad neuroendocrine-immune correlation is essential for NEN treatment. In this review, we summarize the immune microenvironment characteristics, advances in immunotherapy, predictive biomarkers of ICI efficacy for NENs, and the effects of common endocrine hormones on the immune system, highlighting possible new application areas for this promising treatment in neglected NENs.

Expert Insights on Current Treatments for Hepatocellular Carcinoma: Clinical and Molecular Approaches and Bottlenecks to Progress

Hepatocellular carcinoma (HCC) is a primary liver tumor that typically occurs in the setting of chronic liver disease/cirrhosis. Treatment modalities for HCC have evolved and given the variety of treatment options, a multi-disciplinary approach requiring input from surgical, medical, and radiation oncology, hepatology, and interventional radiology is necessary. Multiple advances have been made over the last decade regarding treatment of HCC, especially advanced disease. Resection and transplantation remain as cornerstone curative-intent treatment options. For patients who are not candidates for curative-intent therapy, exciting progress has been made in molecular and cellular approaches to systemic therapy for HCC including immunotherapies and tyrosine kinase inhibitors. Although the prognosis for advanced HCC remains poor, the armamentarium of therapies has increased, and valuable years of life can be gained with these therapies. While the main therapeutic modality for early-stage disease remains resection, multimodal immunotherapy has emerged as first-line treatment for advanced disease. We herein review different clinical and molecular treatment modalities related to the treatment of HCC, as well as provide insights into future directions for HCC treatment. We highlight how research and progress are needed to move into a new era of molecular and cellular treatments.

Immune Checkpoint Inhibitor Therapy in Neuroendocrine Tumors

Neuroendocrine tumors (NETs) occur in various regions of the body and present with complex clinical and biochemical phenotypes. The molecular underpinnings that give rise to such varied manifestations have not been completely deciphered. The management of neuroendocrine tumors (NETs) involves surgery, locoregional therapy, and/or systemic therapy. Several forms of systemic therapy, including platinum-based chemotherapy, temozolomide/capecitabine, tyrosine kinase inhibitors, mTOR inhibitors, and peptide receptor radionuclide therapy have been extensively studied and implemented in the treatment of NETs. However, the potential of immune checkpoint inhibitor (ICI) therapy as an option in the management of NETs has only recently garnered attention. Till date, it is not clear whether ICI therapy holds any distinctive advantage in terms of efficacy or safety when compared to other available systemic therapies for NETs. Identifying the characteristics of NETs that would make them (better) respond to ICIs has been challenging. This review provides a summary of the current evidence on the value of ICI therapy in the management of ICIs and discusses the potential areas for future research.

Ipilimumab plus nivolumab in avelumab-refractory Merkel cell carcinoma: a multicenter study of the prospective skin cancer registry ADOREG

Merkel cell carcinoma is a rare, highly aggressive skin cancer with neuroendocrine differentiation. Immune checkpoint inhibition has significantly improved treatment outcomes in metastatic disease with response rates to programmed cell death protein 1/programmed cell death 1 ligand 1 (PD-1/PD-L1) inhibition of up to 62%. However, primary and secondary resistance to PD-1/PD-L1 inhibition remains a so far unsolved clinical challenge since effective and safe treatment options for these patients are lacking.Fourteen patients with advanced (non-resectable stage III or stage IV, Union international contre le cancer 2017) Merkel cell carcinoma with primary resistance to the PD-L1 inhibitor avelumab receiving subsequent therapy (second or later line) with ipilimumab plus nivolumab (IPI/NIVO) were identified in the prospective multicenter skin cancer registry ADOREG. Five of these 14 patients were reported previously and were included in this analysis with additional follow-up. Overall response rate, progression-free survival (PFS), overall survival (OS) and adverse events were analyzed.All 14 patients received avelumab as first-line treatment. Thereof, 12 patients had shown primary resistance with progressive disease in the first tumor assessment, while two patients had initially experienced a short-lived stabilization (stable disease). Six patients had at least one systemic treatment in between avelumab and IPI/NIVO. In total, 7 patients responded to IPI/NIVO (overall response rate 50%), and response was ongoing in 4 responders at last follow-up. After a median follow-up of 18.85 months, median PFS was 5.07 months (95% CI 2.43-not available (NA)), and median OS was not reached. PFS rates at 12 months and 24 months were 42.9% and 26.8 %, respectively. The OS rate at 36 months was 64.3%. Only 3 (21%) patients did not receive all 4 cycles of IPI/NIVO due to immune-related adverse events.In this multicenter evaluation, we observed high response rates, a durable benefit and promising OS rates after treatment with later-line combined IPI/NIVO. In conclusion, our patient cohort supports our prior findings with an encouraging activity of second-line or later-line IPI/NIVO in patients with anti-PD-L1-refractory Merkel cell carcinoma.

Management and Prognosis of Cardiac Metastatic Merkel Cell Carcinoma: A Case-Control Study and Literature Review

Merkel cell carcinoma (MCC), an aggressive neuroendocrine skin cancer, has a high rate (20%) of distant metastasis. Within a prospective registry of 582 patients with metastatic MCC (mMCC) diagnosed between 2003-2021, we identified 9 (1.5%) patients who developed cardiac metastatic MCC (mMCC). We compared overall survival (OS) between patients with cardiac and non-cardiac metastases in a matched case-control study. Cardiac metastasis was a late event (median 925 days from initial MCC diagnosis). The right heart was predominantly involved (8 of 9; 89%). Among 7 patients treated with immunotherapy, 6 achieved a complete or partial response of the cardiac lesion. Among these 6 responders, 5 received concurrent cardiac radiotherapy (median 20 Gray) with immunotherapy; 4 of 5 did not have local disease progression or recurrence in the treated cardiac lesion. One-year OS was 44%, which was not significantly different from non-cardiac mMCC patients (45%, p = 0.96). Though it occurs relatively late in the disease course, cardiac mMCC responded to immunotherapy and/or radiotherapy and was not associated with worse prognosis compared to mMCC at other anatomic sites. These results are timely as cardiac mMCC may be increasingly encountered in the era of immunotherapy as patients with metastatic MCC live longer.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.