Oral Azacitidine for the Treatment of Relapsed or Refractory T-cell Large Granular Lymphocytic Leukemia

Inclusion Criteria: * Age 18 or older * Diagnosis of T-LGLL defined as: CD3+CD8+ cell population \> 650/mm\^3 and the presence of a clonal T-cell receptor (within 1 month of diagnosis). This also includes patients with rare T-LGLL variants include CD4+ T-LGLL, and gamma/delta T-LGLL which can be CD4- and CD8, though patients still must have an LGL cell population \>500 cells/mm3 and the presence of a clonal T-cell receptor within 1 month of diagnosis or relapse. Note: patients with myelodysplastic syndrome (MDS)-like T-LGLL may be included with principal investigator (PI) approval even if CD3+CD8+ cell population is \< 650/mm\^3, though +TCR is required. Natural-killer (NK) large granular lymphocytic leukemia (LGL) is also permitted, provided there is a clonal NK-cell population noted with \> 500 cells/mm\^3 * Failed at least one line of frontline therapy; off treatment for at least 14 days or 5 half-lives, whichever is longer * Require Treatment for T-LGLL (One or more required) * Symptomatic anemia with hemoglobin \< 10 g/dL * Transfusion-dependent anemia * Neutropenia with absolute neutrophil count (ANC) \< 500/mm\^3 * Neutropenia with ANC \< 1500/mm\^3 with recurrent infections * Platelet count \>= 50 x 10\^9/L * Serum creatinine =\< 2 x the upper limit of normal (ULN) * Total bilirubin =\< 1.5 x ULN (patients with Gilbert's syndrome with a bilirubin \> 1.5 x ULN permitted) * Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) =\< 1.5 x ULN * Eas…