Characterization of Immune Evasion in Merkel Cell Carcinoma

Merkel cell carcinoma (MCC) is a rare, neuroendocrine skin carcinoma that is caused by the Merkel cell polyomavirus (MCPyV) in 80% of cases and by ultraviolet (UV) damage in 20% of cases. MCC should theoretically elicit a strong cytotoxic T cell response due to the high neoantigen and viral antigen burden in MCPyV- and MCPyV+ MCC, respectively. However, MCC often escapes immune recognition and is associated with very poor prognosis at advanced stages. To systemically identify mechanisms of immune evasion in MCC, we established 11 robust MCC lines from either primary tumors or patient-derived xenografts (7 MCPyV+ and 4 MCPyV-). We then characterized these tumors and cell lines by whole exome sequencing (WES), RNA-sequencing, scRNA-sequencing, ATAC-seq, and whole genome bisulfite sequencing (WGBS). We also studied MCC transcriptional subtypes, utilizing bulk and scRNA-sequencing datasets of patient-derived tumors and cell lines to investigate profiles of neuroendocrine gene expression. The genes linked below define either a neuroendocrine or a non-neuroendocrine phenotype presence within MCC tumors. ]]>
This study included patients diagnosed with Merkel cell carcinoma (MCC) that were enrolled in the tissue collection protocol Merkel Cell Carcinoma Tissue and Data Repository (IRB Protocol 09-156). Through this protocol, we were able to collect MCC biopsy specimens (excess surgical specimens along with matched blood and sera) from patients treated at the Dana-Farber/Brigham and Women's Cancer Center Merkel Cell Carcinoma Center of Excellence.]]>