AZD6738 for Patients With Progressive MDS or CMML

Inclusion Criteria Patients must have a diagnosis of recurrent, persistent, or progressive myelodysplastic syndrome (MDS) or chronic myelomonocytic leukemia (CMML) according to WHO 2016 diagnostic criteria: * For patients with higher-risk MDS (Intermediate, High, or Very High by IPSS-R, score \>3.5), they must have been unresponsive to 4 cycles of decitabine or 6 cycles of azacitidine, progressed on any prior HMA, or intolerant of prior treatment with either azacitidine or decitabine (HMA) chemotherapy. * For patients with CMML, they must have received prior HMA chemotherapy and have been unresponsive to, progressed on, or be intolerant of this therapy; or those who decline or are not felt to be candidates for HMA chemotherapy. * Patients with MDS or CMML that has recurred after prior allogeneic stem cell transplantation. * For patients with lower-risk MDS (Low or Intermediate by IPSS-R, score ≤ 3.5, or any score post-HMA), they must be transfusion-dependent according to IWG criteria and must either be unresponsive to/progressed after prior ESA therapy or have an erythropoietin level \> 500 U/L, who are not felt to be candidates for or lack other treatment options. * Female and male patients aged ≥ 18 years. * ECOG performance status ≤2. * All participants must have adequate organ and marrow function as defined below within 21 days prior to study enrollment: * Total bilirubin \< 1.5 mg/dL unless due to Gilbert's (\<3.0 mg/dL) * AST(SGOT)/ALT(SGPT) ≤ 2.5 × institutional uppe…