A Study of ASTX030 (Cedazuridine in Combination With Azacitidine) in MDS, CMML, or AML

Inclusion Criteria:

Phase 2:

1. Has Confirmed MDS, CMML, MDS/MPN or AML diagnosis who are candidates to receive andbenefit from single agent azacitidine and as applicable according to local countryapprovals and/or local institution standard practice.

Phase 3:

1. Has confirmed MDS or CMML and is a candidate to receive and benefit from singleagent azacitidine as applicable according to local country approvals and/or localinstitution standard practice: a) French-American-British myelodysplastic syndrome subtypes: refractory anemia (RA)or refractory anemia with ringed sideroblasts (if accompanied by neutropenia orthrombocytopenia or requiring transfusions), refractory anemia with excess blasts (RAEB), refractory anemia with excess blasts in transformation (RAEB-T), and CMML orMDS with intermediate-2 or high risk MDS according to the International PrognosticScoring System (IPSS).

2. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1.

3. Participants with adequate organ function.

4. For participants with prior allogeneic stem cell transplant, no evidence ofgraft-versus-host disease (GVHD).

5. Participants with no major surgery within 3 weeks before first study treatment.

6. Participants with no cytotoxic chemotherapy (excluding hydroxyurea) within 4 weeksbefore first study treatment.

7. Participants with projected life expectancy of at least 12 weeks.

Exclusion Criteria:

Phase 2 and 3:

1. Has an active uncontrolled gastric or duodenal ulcer.

2. Has poor medical risk because of other conditions.

3. Has known human immunodeficiency virus (HIV) infection.

4. Is known to be positive for Hepatitis B or C infection.

5. Has a life-threatening illness.

6. Has a history of other malignancies prior to study entry, with the exception ofadequately treated in situ carcinoma of the breast or cervix uteri; localized basalcell carcinoma or squamous cell carcinoma of the skin; previous malignancy confinedand surgically resected or adequately treated and controlled with other modalities;and any early stage malignancy for which no definitive therapy is required.

7. Participants with MDS/MPN including CMML who have clinical extramedullary diseaseincluding clinically palpable hepatomegaly or splenomegaly.

8. Has previous treatment with more than 1 cycle of decitabine, azacitidine, orguadecitabine (Phases 2 and 3 only).

9. Has been treated with any investigational drug or therapy within 2 weeks, or 5half-lives, whichever is longer, before the protocol-defined first dose of studytreatment, or ongoing clinically significant adverse events from previous treatmentwith investigational drug or therapy.

10. Has a known or suspected hypersensitivity to cedazuridine or azacitidine or any oftheir excipients.