ASTX727 & Retifanlimab-dlwr for Advanced Merkel Cell After Progression on Anti-PD-(L)1

Inclusion Criteria: * Individuals age ≥ 18 years at the time of consent * ECOG Performance Status of 0-2 * Histological or cytological evidence/confirmation of Merkel cell carcinoma (MCC) * Must have unresectable stage III/IV MCC per American Joint Committee on Cancer (AJCC) 8th edition. Participants must be considered unresectable based on the judgment of the treating physician * Participants must have progressed on prior programmed cell death protein-1 (PD-1) or programmed death-ligand 1(PD-L1) inhibitor-based therapy. Participants must have received at least 2 doses of anti-PD-1 or anti-PD-L1 inhibitor. Relapsed/refractory disease from prior adjuvant PD-1 or PD-L1 inhibitor is permitted. Prior treatment with retifanlimab is permitted. * Demonstrate adequate organ and marrow function; all screening labs to be obtained within 28 days prior to registration Exclusion Criteria: * Prior treatment with a hypomethylating agent (HMA) (e.g., azacitidine, decitabine, guadecitabine) * History of clinically significant intolerance, hypersensitivity, or treatment discontinuation of an anti-PD-1 or anti-PD-L1 inhibitor due to grade 3 or greater immune-related adverse events (irAEs). Participants who are able to be successfully rechallenged with anti-PD-(L)1 inhibitor without recurrence of grade 3 or greater irAEs are permitted on study. Participants with irreversible toxicity that is not reasonably expected to be exacerbated by study drug(s) may be included (e.g. hearing loss, hypothy…