Ropeginterferon Alfa-2b for the Treatment of Myelodysplastic Syndrome/Myeloproliferative Neoplasm Overlap Syndromes and Chronic Myelomonocytic Leukemia

Inclusion Criteria: * Male or female ≥ 18 years of age at time of consent * Documentation of a diagnosis of MDS/MPN overlap syndrome based on World Health Organization (WHO) 2022 classification, including CMML, MDS/MPN with neutrophilia, myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), or MDS/MPN, not otherwise specified, by local pathology review, and deemed to potentially benefit from study participation by the investigator * Written informed consent obtained from participant or participant's legal representative and ability for participant to comply with the requirements of the study * Blast =\< 10% by marrow immunohistochemistry stain * Platelet count of \> 50,000/uL * Absolute neutrophils count (ANC) of \> 1000/uL * Eastern Cooperative Oncology Group (ECOG) performance status (PS) =\< 2 * Serum creatinine =\< 2.5 mg/dL * Serum direct bilirubin \< 2.0 mg/dL * Serum transaminase \< 2.5 times the upper limit of the normal range (ULN) or \< 5 times ULN if the transaminase elevation was deemed related to the MDS/MPN Exclusion Criteria: * Prior therapy with interferon or pegylated interferon product, or azacitidine * Spleen overtly enlarged by physical exam (eg. greater than 5 fingerbreadth below costal margin) * Other standard (including erythropoietin-stimulating agents \[ESA\] or luspatercept) or experimental therapy for MDS/MPN within 28 days of starting study therapy with the exception of hydroxyurea, which is allowe…