Molecular and immune targets in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer and often confers a good prognosis. Though surgery is the gold standard of treatment, unresectable or metastatic disease can necessitate systemic therapy. Of systemic agents, there is increasing interest in the use of immunotherapies and targeted therapy. Further study into the driver mutations in cSCC has identified opportunities for targeted therapy. In this review, we discuss both current and investigational immune and molecular targets of therapy for cSCC.     

Management of Merkel cell carcinoma

Merkel cell carcinoma is an uncommon cutaneous malignancy. Although it is rare, Merkel cell carcinoma has been described as the most malignant primary skin tumor. It is therefore important that once diagnosed, Merkel cell carcinoma is treated appropriately. The aim of this short review is to provide a summary of the available literature to guide clinicians in the future management of such patients. Inevitably in such a rare disease, there are no randomized trials of therapy. The treatment of individual patients will rely on opinion as much as the ‘evidence’.     

Polyomavirus-driven Merkel cell carcinoma: Prospects for therapeutic vaccine development

Great strides have been made in cancer immunotherapy including the breakthrough successes of anti-PD-(L)1 checkpoint inhibitors. In Merkel cell carcinoma (MCC), a rare and aggressive skin cancer, PD-(L)1 blockade is highly effective. Yet, ~50% of patients either do not respond to therapy or develop PD-(L)1 refractory disease and, thus, do not experience long-term benefit. For these patients, additional or combination therapies are needed to augment immune responses that target and eliminate cancer cells. Therapeutic vaccines targeting tumor-associated antigens, mutated self-antigens, or immunogenic viral oncoproteins are currently being developed to augment T-cell responses. Approximately 80% of MCC cases in the United States are driven by the ongoing expression of viral T-antigen (T-Ag) oncoproteins from genomically integrated Merkel cell polyomavirus (MCPyV). Since T-Ag elicits specific B- and T-cell immune responses in most persons with virus-positive MCC (VP-MCC), and ongoing T-Ag expression is required to drive VP-MCC cell proliferation, therapeutic vaccination with T-Ag is a rational potential component of immunotherapy. Failure of the endogenous T-cell response to clear VP-MCC (allowing clinically evident tumors to arise) implies that therapeutic vaccination will need to be potent anśd synergize with other mechanisms to enhance T-cell activity against tumor cells. Here, we review the relevant underlying biology of VP-MCC, potentially applicable therapeutic vaccine platforms, and antigen delivery formats. We also describe early successes in the field of therapeutic cancer vaccines and address several clinical scenarios in which VP-MCC patients could potentially benefit from a therapeutic vaccine.     

Prokineticins and Merkel cell polyomavirus infection in Merkel cell carcinoma

Background:

Prokineticin-1 (PROK1) and prokineticin-2 (PROK2) are chemokine-like proteins that may influence cancer growth by regulating host defence and angiogenesis. Their significance in viral infection-associated cancer is incompletely understood. We studied prokineticins in Merkel cell carcinoma (MCC), a skin cancer linked with Merkel cell polyomavirus (MCPyV) infection.

Methods:

Carcinoma cell expression of PROK1 and PROK2 and their receptors (PROKR1 and PROKR2) was investigated with immunohistochemistry, and tumour PROK1 and PROK2 mRNA content with quantitative PCR from 98 MCCs. Subsets of tumour infiltrating leukocytes were identified using immunohistochemistry.

Results:

Merkel cell polyomavirus-positive MCCs had higher than the median PROK2 mRNA content, whereas MCPyV-negative MCCs contained frequently PROK1 mRNA. Cancers with high tumour PROK2 mRNA content had high counts of tumour infiltrating macrophages (CD68+ and CD163+ cells). Patients with higher than the median PROK2 mRNA content had 44.9% 5-year survival compared with 23.5% among those with a smaller content (hazard ratio (HR): 0.53; 95% confidence interval (CI): 0.34–0.84; P=0.005), whereas the presence of PROK1 mRNA in tumour was associated with unfavourable survival (P=0.052).

Conclusions:

The results suggest that prokineticins are associated with MCPyV infection and participate in regulation of the immune response in MCC, and may influence outcome of MCC patients.     

Predictors of immunotherapy benefit in Merkel cell carcinoma

Merkel cell carcinoma is a rare cancer for which immune checkpoint blockade is standard-of-care for recurrent/metastatic disease. However, not all patients benefit from immunotherapy. A greater understanding of molecular mechanisms and predictive biomarkers are unmet needs. We retrospectively analyzed electronic health records and next-generation sequencing data of 45 patients treated at our institution from 2013 to 2020 to understand clinical and genomic correlates of benefit from immunotherapy. Our cohort predominantly included individuals with stage III disease at primary disease diagnosis and individuals with stage IV disease at recurrent/metastatic disease diagnosis. Most received immunotherapy as first-line treatment. 43% experienced objective response (median duration of response 24.2 months, 95% confidence interval 8.8-not reached). Median overall survival was 15.5 months (95% confidence interval 9.0–28.7) (median follow-up 25.2 months). Less advanced stage at primary disease diagnosis and shorter disease-free interval between completion of initial treatment and recurrence were each associated with greater odds of response (odds ratio of 0.06, p = 0.04 for stage; odds ratio 0.75, p = 0.05 for disease-free interval). Single-nucleotide variants in ARID2 and NTRK1 were associated with response (p = 0.05, without Bonferroni correction), while none of Merkel cell polyomavirus status, total mutational burden, ultraviolet mutational signatures, and copy-number alterations predicted outcomes. Patients with shorter disease-free interval may be particularly suitable immunotherapy candidates. Our molecular findings point to ARID2 and NTRK1 as potential predictive markers and/or therapeutic targets (e.g., with Trk inhibitors), although this association needs to be confirmed in a larger sample.     

PD-L1 blockade with avelumab: A new paradigm for treating Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare and aggressive neuroendocrine skin cancer. Until recently, no durable treatment options were available for patients with advanced disease. As an immunogenic cancer, MCC was hypothesized to be a candidate for PD-L1/PD-1 targeted therapy. On March 23, 2017 the US Food and Drug Administration granted accelerated approval for avelumab, an anti-PD-L1 monoclonal antibody, for the treatment of metastatic MCC on the basis of the JAVELIN Merkel 200 trial. Here we examine the results and implications of this pivotal study, published in Lancet Oncology by Kaufman et al., as well as current developments in the use of immune-checkpoint therapies for treating patients with MCC.     

Cardiac metastasis from Merkel cell skin carcinoma

A 54-year-old woman presented with cardiac metastasis of a Merkel cell carcinoma. Chemotherapy was not effective for the metastasis sites; therefore, radiotherapy was performed for the metastatic cardiac tumors, and it reduced the volume of the cardiac tumors. Cardiac metastasis from Merkel cell carcinoma is rare. Radiotherapy for metastatic cardiac tumors from Merkel cell carcinoma is useful as palliative treatment when the response to chemotherapy is poor.     

Avelumab: a new standard for treating metastatic Merkel cell carcinoma

Introduction: Merkel cell carcinoma (MCC) is a rare and aggressive skin cancer. Although MCC is chemosensitive, responses to traditional chemotherapeutic agents are not durable. Avelumab, a novel anti-PD-L1 immune checkpoint inhibitor, recently became the first FDA-approved agent for the treatment of metastatic MCC and represents a new option to improve patient survival.

Areas covered: This article presents an overview of MCC and summarizes the development of avelumab in the treatment of metastatic MCC. Preclinical studies, phase 1 and phase 2 clinical trials, and the safety profile of avelumab are reviewed. Future perspectives and ongoing studies are also discussed.

Expert commentary: Avelumab demonstrated rapid and durable responses and a manageable safety profile in the treatment of metastatic MCC. Patient outcomes are favorable when compared to historical responses to standard chemotherapy. Ongoing clinical trials will continue to characterize avelumab and its optimal use in MCC therapy.     

Merkel cell carcinoma subgroups by Merkel cell polyomavirus DNA relative abundance and oncogene expression

Merkel cell polyomavirus (MCPyV) was recently discovered in Merkel cell carcinoma (MCC), a clinically and pathologically heterogeneous malignancy of dermal neuroendocrine cells. To investigate this heterogeneity, we developed a tissue microarray (TMA) to characterize immunohistochemical staining of candidate tumor cell proteins and a quantitative PCR assay to detect MCPyV and measure viral loads. MCPyV was detected in 19 of 23 (74%) primary MCC tumors, but 8 of these had less than 1 viral copy per 300 cells. Viral abundance of 0.06–1.2 viral copies/cell was directly related to presence of retinoblastoma gene product (pRb) and terminal deoxyribonucleotidyl transferase (TdT) by immunohistochemical staining (p ≤ 0.003). Higher viral abundance tumors tended to be associated with less p53 expression, younger age at diagnosis and longer survival (p ≤ 0.08). These data suggest that MCC may arise through different oncogenic pathways, including ones independent of pRb and MCPyV.     

An unusual pattern of metastases from Merkel cell carcinoma

An unusual case of Merkel cell carcinoma is presented in which the time course to development of nodal and haematogenous metastases was protracted and the predominant site of metastatic disease was small bowel.     

The Merkel cell carcinoma challenge

Merkel cell carcinoma (MCC) is a highly aggressive neuroendocrine carcinoma of the skin that occurs primarily in elderly or immunocompromised patients. For this report, the authors reviewed the diagnostic challenges associated with MCC encountered on their fine‐needle aspiration (FNA) service and also conducted an in‐depth review of the literature on MCC. A computer search for patients who were diagnosed with MCC by FNA at the authors' institution from 2006 to 2010 was conducted, and 5 patients were selected for cytologic and immunochemical analyses based on their varied and diagnostically challenging clinical presentations. The 5 selected patients had clinical findings commonly associated with MCC, including advanced age (4 of the 5 patients were ages 75‐85 years) and a history of previous malignancies (3 of the 5 patients had a history of previous malignancy), and 1 patient was diagnosed with a concomitant low‐grade lymphoma. The patients and their disease illustrated the protean clinical presentation of MCC and the clinical and cytologic challenges associated with this neoplasm. The current findings indicate the need for cytopathologists to be aware of the deceptive presentation of this neoplasm and its cytologic and immunochemical features to correctly diagnose this insidious neoplasm. Cancer (Cancer Cytopathol) 2013;121:179–188. © 2012 American Cancer Society.     

Current status of studies on targeted therapy for renal cell carcinoma

Renal cell carcinoma (RCC) is regarded as one of the most refractory malignancies. A further study of the molecular mechanism of RCC formation has led to a series of successful examples for treatment of patients with advanced RCC. Over the past 20 years, a nonspecific immunotherapy, with cytokines, has been employed as the gold standard for therapy of metastatic RCC. However, with scientific development and clinical testing of new drugs, targeted molecular cancer therapy has become a focus of interest. At the same time, with a better understanding of RCC,the treatment method has converged on anti-vascular endothelial growth factor (VEGF) and related molecular-targeted pathways.A large amount of research and numerous clinical trials have demonstrated the clinical efficacy of the targeted molecular therapies in patients with metastatic RCC. For example sorafenib and sunitinib were approved, in 2005 and 2006 respectively, by the U.S. FDA for treating advanced RCC. In this report, issues such as the importance of VEGF in RCC and the studies of bevacizumab,sunitinib and sorafenib in treating metastatic RCC etc., are reviewed.     

Prospective study of Merkel cell polyomavirus and risk of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is a rare type of skin cancer that has a characteristically increased incidence among immunosuppressed subjects. The DNA of Merkel cell polyomavirus (MCV) is regularly found in most MCC tumors. We investigated whether Merkel cell polyomavirus (MCV) infection increases the risk for future MCC. Two large biobank cohorts (Southern Sweden Microbiology Biobank and the Janus Biobank), containing samples from 856,000 healthy donors, were linked to the Cancer Registries in Sweden and Norway to identify cases of MCC occurring up to 30 years after donation of a serum sample. For each of the 22 cases (nine males and 13 females), four matched controls were included. The serum samples were analyzed with an MCV neutralization assay and for IgG antibodies to MCV pseudovirions, using JC polyomavirus and cutaneous human papillomaviruses as control antigens. An increased risk for future MCC was associated both with high levels of MCV antibodies [OR 4.4, 95% CI 1.3–17.4] and with MCV neutralizing activity (OR 5.3, 95% CI 1.3–32.3). In males, MCV seropositivity was not associated to MCC risk, whereas the risk was strongly increased in females, both for high levels of MCV antibodies (OR 7.0, 95% CI 1.6–42.8) and for MCV neutralizing activity (OR 14.3, 95% CI 1.7–677). In conclusion, we found prospective evidence that MCV infection is associated with an increased risk for future MCC, in particular among females.     

Neurologic complications of Merkel cell carcinoma

We describe a 61-year-old man with a multiple neurologic complication of Merkel cell carcinoma, a rare skin cancer. An enhancing brain mass, and cytologically proven leptomeningeal disease produced a succession of symptoms including seizures, bilateral radiculopathies, myoclonus, a cauda equina syndrome and altered mental status. Aggressive treatment prolonged his survival marginally.     

Recurrence after complete resection and selective use of adjuvant therapy for stage I through III Merkel cell carcinoma

BACKGROUND:

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine neoplasm whose natural history is poorly understood. Here, the authors describe their experience with a large cohort of patients who were treated at a single institution to describe patterns of recurrence after curative therapy.

METHODS:

Review of a prospective database was performed. Patient‐related, tumor‐related, and treatment‐related variables were recorded, and the site and timing of initial recurrence were recorded. Factors associated with receipt of adjuvant therapy and recurrence were determined.

RESULTS:

In total, 364 patients with stage I through III MCC who underwent complete resection were identified. Adjuvant local radiation therapy (RT), lymph node RT, and chemotherapy were received selectively by 23%, 23%, and 15% of patients, respectively. Factors associated with the receipt of adjuvant therapy included younger age, primary tumor features (larger size, lymphovascular invasion [LVI], positive margin excision), and increasing pathologic stage. With median follow‐up of 3.6 years, 108 patients (30%) developed a recurrence, including 11 local recurrences (3%), 12 in‐transit recurrences (3%), 43 lymph node recurrences (12%), and 42 distant recurrences (12%). Clinically involved lymph nodes, primary tumor LVI, and a history of leukemia/lymphoma were predictive of recurrence. The majority of recurrences (80%) occurred in patients who had clinically involved lymph nodes or patients who did not undergo pathologic lymph node evaluation.

CONCLUSIONS:

A low recurrence rate in patients with clinically lymph node‐negative MCC was achieved with adequate surgery (including sentinel lymph node biopsy) and the selective use of adjuvant RT for high‐risk tumors. In contrast, patients with clinically lymph node‐positive MCC had significantly higher rates of recurrence, especially distant recurrence. The authors concluded that contemporary natural history studies are critical in designing treatment pathways and clinical trials for MCC. Cancer 2011. © 2011 American Cancer Society.     

Solitary regional bony recurrence in Merkel cell carcinoma

This case report of recurrent Merkel cell carcinoma between radiotherapy fields for primary site and regional nodes supports the value of postoperative radiotherapy to the primary site, the intervening lymphatics and draining nodes.     

Human Merkel cell polyomavirus infection I. MCV T antigen expression in Merkel cell carcinoma,lymphoid tissues and lymphoid tumors

Merkel cell polyomavirus (MCV) is a recently discovered human virus closely related to African green monkey lymphotropic polyomavirus. MCV DNA is integrated in ～80% of Merkel cell carcinomas (MCC), a neuroendocrine skin cancer linked to lymphoid malignancies such as chronic lymphocytic leukemia (CLL). To assess MCV infection and its association with human diseases, we developed a monoclonal antibody that specifically recognizes endogenous and transfected MCV large T (LT) antigen. We show expression of MCV LT protein localized to nuclei of tumor cells from MCC having PCR quantified MCV genome at an average of 5.2 (range 0.8–14.3) T antigen DNA copies per cell. Expression of this putative viral oncoprotein in tumor cells provides the mechanistic underpinning supporting the notion that MCV causes a subset of MCC. In contrast, although 2.2% of 325 hematolymphoid malignancies surveyed also showed evidence for MCV infection by DNA PCR, none were positive at high viral copy numbers, and none of 173 lymphoid malignancies examined on tissue microarrays expressed MCV LT protein in tumor cells. As with some of the other human polyomaviruses, lymphocytes may serve as a tissue reservoir for MCV infection, but hematolymphoid malignancies associated with MCC are unlikely to be caused by MCV. © 2009 UICC     

皮肤Ｍｅｒｋｅｌ细胞癌的研究进展

Ｍｅｒｋｅｌ细胞癌（ＭＣＣ）是一种好发于皮肤的少见恶性神经内分泌瘤,预后较差,易局部复发和转移。ＭＣＣ的临床诊断可参考“ＡＥＩＯＵ”五元音法,但必须由组织病理学确诊。ＭＣＣ在高度紫外线暴露的地区较常见,且与免疫抑制密切相关。ＭＣＣ可能与Ｍｅｒｋｅｌ细胞多瘤病毒（ＭＣＰｙＶ）相关。目前ＭＣＣ尚无成熟的治疗方案,但首选手术治疗并常常辅助放疗或化疗。     

An intact retinoblastoma protein-binding site in Merkel cell polyomavirus large T antigen is required for promoting growth of Merkel cell carcinoma cells

Merkel cell carcinoma (MCC) is a highly aggressive skin cancer that frequently harbours Merkel cell polyomavirus (MCV) DNA integrated in the genome of the tumor cells. In our study, we elaborate our recent finding that MCV-positive MCC cell lines require the expression of the viral T antigens (TA). Indeed, in a xeno-transplantation model, we prove that TA expression is essential also in an in vivo situation, as knock down of TA leads to tumor regression. Moreover, rescuing TA short hairpin RNA (shRNA)-treated MCV-positive MCC cells by ectopic expression of shRNA-insensitive TAs clearly demonstrates that the observed effect is caused by TA knockdown. Notably, introduction of a mutation in the LTA protein interfering with LTA binding to the retinoblastoma protein (RB) ablated this rescue. The importance of this interaction was further confirmed as LTA-specific knockdown leads to explicit cell growth inhibition. In summary, the presented data demonstrate that established MCV-positive MCC tumors critically depend on TA expression, in particular the LTA and RB interaction, for sustained tumor growth. Consequently, interference with LTA/RB interaction appears as promising strategy to treat MCC.     

Detection of Merkel cell virus and correlation with histologic presence of Merkel cell carcinoma in sentinel lymph nodes

Background:

Adjuvant treatment can dramatically improve the survival of patients with metastatic Merkel cell carcinoma (MCC), making early, accurate detection of nodal disease critical. The purpose of this study was to correlate Merkel cell virus (MCV) detection with histopathologic disease in sentinel lymph nodes (SLNs) of MCC.

Methods:

Merkel cell carcinoma cases with SLN (n=25) were compared with negative controls (n=27). Viral load was obtained by quantitative polymerase chain reaction (PCR) for regions VP1 and LT3 of MCV. Histopathologic disease and viral load were correlated.

Results:

Merkel cell virus was detected in 16 out of 17 (94%) of primary MCC (mean viral load (MVL)=1.44 copies per genome). Viral load in the negative controls was <0.01 copies per genome. Merkel cell carcinoma was present in 5 out of 25 (20%) SLN by histopathology, and MCV was detected in 11 out of 25 (44%) MCC SLN (MVL=1.68 copies per genome). In all, 15 out of 25 (60%) SLN showed correlation between histologic and MCV results. In all, 2 out of 25 (8%) samples were histopathologically positive and PCR negative. Of note, 8 out of 25 (32%) samples had detectable MCV without microscopic disease.

Conclusion:

Patients with positive SLN for MCV even if negative by histopathology were identified. The application of molecular techniques to detect subhistologic disease in SLN of MCC patients may identify a subset of patients who would benefit from adjuvant nodal treatment.