Study To Evaluate The Safety, Tolerability And Immunogenicity Of 4 mg Of ITI-3000 In Patients With Polyomavirus-Positive Merkel Cell Carcinoma (MCC)

Inclusion Criteria: * Evidence of Merkel cell polyomavirus (MCPyV) in the tumor at initial presentation (pre-therapy) can be provided by a positive anti-MCPyV oncoprotein antibody AMERK Test. * Eligible participants have to be both be diagnosed and have completed SOC surgical and/or radiation therapy at least 1 year prior to enrollment in the study and have no evidence of active disease (NEAD). * Participants who were previously diagnosed with MCC and had recurrence and also exhibited no evidence of active disease (NEAD) for more than 2 years prior to enrollment in the study. * Age ≥ 18 years. * Karnofsky performance status (PS) ≥ 70 or ECOG PS 0-1. * Participant has a predicted life expectancy ≥ 3 months. * Participant provided signed and dated informed consent prior to initiation of any study procedures. * Participant has adequate renal function (creatinine ≤ 1.5 times the upper limit of normal \[ULN\]) or a glomerular filtration rate (GFR) of ≥ 50 mL/min/1.73 m2). * Participant has adequate hepatic function, as evidenced by a total bilirubin ≤ 1.5 times the ULN, aspartate transaminase (AST), and/or alanine transaminase (ALT) ≤ 3 times the ULN. * Participant has adequate bone marrow function, as evidenced by hemoglobin ≥ 9.0 g/dL in the absence of transfusion within the previous 72 hours, platelet count ≥ 100×109cells/L, and absolute neutrophil count (ANC) ≥ 1.5×109 cells/L. * Participant and his/her partner agree to use adequate contraception after providing written infor…