Gene-Modified Immune Cells (FH-MCVA2TCR) in Treating Patients With Metastatic or Unresectable Merkel Cell Cancer

Inclusion Criteria: * EVALUATION: Metastatic or unresectable Merkel cell polyomavirus (MCPyV)-associated Merkel cell carcinoma (VP-MCC) that has progressed on or after prior treatment with a PD-1 axis immune checkpoint inhibitor. * EVALUATION: Individuals that may be consented to undergo evaluation to determine potential eligibility must have a history of metastatic or unresectable Merkel cell carcinoma (MCC) (as documented by medical record). * EVALUATION: Be 18 years of age or older. * EVALUATION: Be capable of understanding and providing informed consent. * Participants must have metastatic or unresectable, histologically confirmed virus-positive MCC. Confirmation of diagnosis must be or have been performed by internal pathology review of initial or subsequent biopsy or other pathologic material at Fred Hutch/Seattle Cancer Care Alliance (SCCA). * Approximately 80% of MCCs are caused by Merkel cell polyomavirus (MCPyV) T Antigens and the treatment is expected to only be effective in this population. Merkel cell polyomavirus positivity may be established through one of two means: positive Merkel cell polyomavirus T antigen serology (preferred) or immunohistochemistry of a primary or metastatic MCC tumor lesion (if T antigen seronegative). * MCPyV T Antigen serology will be performed with the anti-Merkel cell panel (AMERK) assay run through the University of Washington Medical Center Laboratory Medicine Clinical Immunology Laboratory. Positivity will be defined as a Merkel …