Linda C. Wang

Improved detection suggests all Merkel cell carcinomas harbor Merkel polyomavirus

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

Tumor-Specific T Cells in Human Merkel Cell Carcinomas: A Possible Role for Tregs and T-Cell Exhaustion in Reducing T-Cell Responses

Merkel cell carcinomas (MCC) are rare but highly malignant skin cancers associated with a novel polyomavirus. MCC tumors were infiltrated by T cells, including effector, central memory and regulatory T cells. Infiltrating T cells showed markedly reduced activation as evidenced by reduced expression of CD69 and CD25. Treatment of MCC tumors in vitro with IL-2 and IL-15 led to T cell activation, proliferation, enhanced cytokine production and loss of viable tumor cells from cultures. Expanded tumor-infiltrating lymphocytes showed TCR repertoire skewing and upregulation of CD137. MCC tumors implanted into immunodeficient mice failed to grow unless human T cells in the tumor grafts were depleted with denileukin diftitox, suggesting tumor-specific T cells capable of controlling tumor growth were present in MCC. Both CD4+ and CD8+ FOXP3+ regulatory T cells were frequent in MCC. 50% of non-activated T cells in MCC expressed PD-1, a marker of T-cell exhaustion, and PD-L1 and PD-L2 were expressed by a subset of tumor dendritic cells and macrophages. In summary, we observed tumor-specific T cells with suppressed activity in MCC tumors. Agents that stimulate T cell activity, block Treg function or inhibit PD-1 signaling may be effective in the treatment of this highly malignant skin cancer.

Positron emission tomography/computed tomography imaging in Merkel cell carcinoma: A study of 270 scans in 97 patients at the Dana-Farber/Brigham and Women's Cancer Center

BACKGROUND Merkel cell carcinoma (MCC) is a rare and lethal cutaneous neuroendocrine carcinoma. Imaging is crucial for accurate staging, which remains a strong predictor of survival, as well as earlier detection of recurrence and progression, which are common despite aggressive management. There is no consensus on the role of initial and subsequent imaging for MCC. OBJECTIVE We sought to evaluate the use of 2-fluoro-[(18)F]-deoxy-2-D-glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) in the management of MCC. METHODS In all, 270 FDG-PET/CT studies were performed in 97 patients with pathology-proven MCC at the Dana-Farber/Brigham and Womens Cancer Center, Boston, Mass, from August 2003 to December 2010. RESULTS FDG-PET/CT scans were obtained as part of the initial (61 scans in 61 patients) and subsequent (209 scans in 79 patients) treatment strategies. MCCs were FDG-avid with a mean maximum standardized uptake value of primary lesions of 6.5 (range 1.3-12.9) and a mean maximum standardized uptake value of regional and distant metastases of 7.2 (range 1.5-9.9). FDG-PET/CT upstaged 16% of patients who underwent baseline scans. FDG-PET/CT studies showed that bone and bone-marrow metastases were more common than previously reported, and were often undetected by CT. LIMITATIONS Our study is limited by its retrospective design, and potential referral bias associated with a tertiary care center. CONCLUSIONS FDG-PET/CT performed as part of the initial management strategy tended to upstage patients with more advanced disease. FDG-PET/CT performed as part of the subsequent treatment strategy identified metastatic disease, particularly in bone/bone marrow, which was not seen on CT. FDG-PET/CT imaging is a valuable staging and restaging tool in MCC management.

Merkel Cell Polyomavirus Exhibits Dominant Control of the Tumor Genome and Transcriptome in Virus-Associated Merkel Cell Carcinoma

ABSTRACT Merkel cell polyomavirus is the primary etiological agent of the aggressive skin cancer Merkel cell carcinoma (MCC). Recent studies have revealed that UV radiation is the primary mechanism for somatic mutagenesis in nonviral forms of MCC. Here, we analyze the whole transcriptomes and genomes of primary MCC tumors. Our study reveals that virus-associated tumors have minimally altered genomes compared to non-virus-associated tumors, which are dominated by UV-mediated mutations. Although virus-associated tumors contain relatively small mutation burdens, they exhibit a distinct mutation signature with observable transcriptionally biased kataegic events. In addition, viral integration sites overlap focal genome amplifications in virus-associated tumors, suggesting a potential mechanism for these events. Collectively, our studies indicate that Merkel cell polyomavirus is capable of hijacking cellular processes and driving tumorigenesis to the same severity as tens of thousands of somatic genome alterations. IMPORTANCE A variety of mutagenic processes that shape the evolution of tumors are critical determinants of disease outcome. Here, we sequenced the entire genome of virus-positive and virus-negative primary Merkel cell carcinomas (MCCs), revealing distinct mutation spectra and corresponding expression profiles. Our studies highlight the strong effect that Merkel cell polyomavirus has on the divergent development of viral MCC compared to the somatic alterations that typically drive nonviral tumorigenesis. A more comprehensive understanding of the distinct mutagenic processes operative in viral and nonviral MCCs has implications for the effective treatment of these tumors. A variety of mutagenic processes that shape the evolution of tumors are critical determinants of disease outcome. Here, we sequenced the entire genome of virus-positive and virus-negative primary Merkel cell carcinomas (MCCs), revealing distinct mutation spectra and corresponding expression profiles. Our studies highlight the strong effect that Merkel cell polyomavirus has on the divergent development of viral MCC compared to the somatic alterations that typically drive nonviral tumorigenesis. A more comprehensive understanding of the distinct mutagenic processes operative in viral and nonviral MCCs has implications for the effective treatment of these tumors.

Treatment of Cutaneous Metastases of Merkel Cell Carcinoma With Surface-Mold Computer-Optimized High-Dose-Rate Brachytherapy

e19010 Background: Merkel cell carcinoma (MCC) is an aggressive cutaneous neuroendocrine carcinoma with great propensity for locoregional recurrence and distant metastases. Despite surgery and radiation therapy, lower extremity in-transit (and retrograde) cutaneous metastases are unfortunately common and present a therapeutic challenge. The often diffuse nature of lower extremity metastases renders negative margin excision unfeasible. Response to chemotherapy is limited and rarely durable. Although MCC is radiosensitive, radiation therapy is technically difficult for multifocal disease over the complex anatomic curvatures of the lower extremities. Methods: The Dana-Farber/Brigham and Womens Cancer Center has overcome these limitations with surface-mold computer-optimized high-dose rate brachytherapy (SMBT). Moldable applicators composed of a thermoplastic material and HDR treatment catheters are created for 3D conformal image-guided brachytherapy, which allows for the efficient and accurate targeting of ...

Metastatic Eccrine Porocarcinoma After Mohs Micrographic Surgery: A Case Report

Case Report A 59-year-old Hispanic woman presented with a 3-year history of a growing nodule on the left ventral forearm, which bled with minor trauma. Physical examination revealed a 2.5-cm pink to violaceous pedunculated nodule with hemorrhagic crusting on a 1.5-cm base (Fig 1). Skin biopsy showed a lobular infiltrative tumor composed of small cuboidal cells forming duct-like lumina that extended into the reticular dermis (Figs 2A to 2C). Higher magnification showed comedonecrosis, nuclear and cytoplasmic pleomorphism, and atypical mitotic figures (Figs 2D to 2F). There was no definitive lymphovascular or perineural invasion. A diagnosis of invasive eccrine porocarcinoma (EPC), a rare malignancy of the eccrine sweat glands, was made. Mohs micrographic surgery (MMS) with negative microscopic margins determined by frozen sections was performed. Two years later, the patient noted a firm nodule in the left axilla. Ultrasound revealed a 3.8 3.8 3.6 cm solid mass and an adjacent 2.1 1.8 1.4 cm hypoechoic mass. Fine needle aspiration core biopsy revealed a poorly differentiated carcinoma morphologically similar to her previous EPC (Figs 3A to 3D). Chest, abdomen, and pelvic computed tomography demonstrated 5.7 4.6 3.7 cm and 2.1 2.0 cm left axillary masses. Positron emission tomography/computed tomography revealed an intensely [F]fluorodeoxyglucose-avid 5.0 4.6 cm left axillary mass with multiple satellite lymph nodes ranging in size from 0.8 to 1.0 cm without distant metastatic involvement (Fig 4). The patient was diagnosed with recurrent regional EPC. The patient underwent a radical left axillary lymphadenectomy. Pathology revealed a poorly differentiated carcinoma with squamous features and extensive tumor necrosis (Figs 5A to 5E) without lymphovascular or perineural invasion, consistent with metastasis from the patient’s known EPC. Immunostaining for estrogen and progesterone receptors was negative. One of 12 additional left axillary lymph nodes was positive for metastatic involvement (Fig 5F). Despite negative surgical margins, the patient underwent postoperative radiation therapy, receiving 54 Gy in 2-Gy fractions. The patient has no evidence of disease clinically or radiographically 6 months after completion of treatment.

Palliative treatment for in-transit cutaneous metastases of Merkel cell carcinoma using surface-mold computer-optimized high-dose-rate brachytherapy.

PurposeThe objective of this study was to evaluate the palliative treatment benefit of surface-mold computer-optimized high-dose-rate brachytherapy (SMBT) for in-transit cutaneous metastases of Merkel cell carcinoma (MCC). MethodsTen patients with in-transit cutaneous MCC metastases were treated with SMBT at the Dana-Farber/Brigham & Women’s Cancer Center between 2006 and 2012. ResultsThe median age at diagnosis was 76 years (range, 63–87 years). Seven patients had in-transit metastases on the lower extremities (70%), 2 patients on the head and neck (20%), and 1 patient on an upper extremity (10%). A total of 152 metastatic MCC lesions were treated with SMBT. All SMBT-treated lesions resolved clinically within a few weeks of therapy. The median follow-up was 34 months (range, 22–85 months). Two of 152 treated lesions recurred during the study period for a local control rate of 99%. Eight patients (80%) developed additional in-transit metastases outside the original SMBT fields. Five of these 8 patients underwent additional SMBT. At study conclusion, 3 patients (30%) are alive without disease, 3 patients (30%) are alive with disease, and 4 patients (40%) died of MCC. DiscussionSurface-mold computer-optimized high-dose-rate brachytherapy offers effective and durable palliation for cutaneous metastases of MCC, although it does not appear to alter disease course.

Merkel cell carcinoma expresses vasculogenic mimicry: demonstration in patients and experimental manipulation in xenografts

Merkel cell carcinoma (MCC) is a highly virulent cutaneous neoplasm that, like melanoma, is a frequent cause of patient morbidity and mortality. The cellular mechanisms responsible for the aggressive behavior of MCC remain unknown. Vasculogenic mimicry (VM) is a phenomenon associated with cancer virulence, including in melanoma, whereby anastomosing laminin networks form in association with tumor cells that express certain endothelial genes. To determine whether VM is a factor in MCC, we employed a relevant xenograft model using two independent human MCC lines. Experimentally induced tumors were remarkably similar histologically to patient MCC, and both contained laminin networks associated with vascular endothelial-cadherin (CD144) and vascular endothelial growth factor receptor 1, as well as Nodal expression typical of VM in melanoma. Moreover, two established chemotherapeutic agents utilized for human MCC, etoposide and carboplatin, induced necrosis in xenografts on systemic administration while enriching for laminin networks in apparently resistant viable tumor regions that persisted. These findings for the first time establish VM-like laminin networks as a biomarker in MCC, demonstrate the experimental utility of the MCC xenograft model, and suggest that VM-rich regions of MCC may be refractory to conventional chemotherapeutic agents.