A study to evaluate the efficacy of APG-2575 (Lisaftoclax) plus azacitidine (AZA) vs. placebo plus AZA in newly diagnosed adult subjects with higher risk myelodysplastic syndrome (Higher Risk-MDS).

Prior treatment

• Previous diagnosis of xxx

Other illness

• Second malignancies or previous malignancies with a disease-free interval of less than 1 year at the time of signing the informed consent (except for subjects with adequately resected cutaneous basal cell or squamous cell carcinoma or resected carcinoma in situ).
• Have history of HSCT.
• Other clinically significant uncontrolled symptoms, including but not limited to: uncontrolled active systemic infection (virus, bacteria or fungi), known clinically active hepatitis B or C, or HIV infection. (as determined by the study physician based on clinical examination assessments).
• Have malabsorption syndrome or other conditions and are not suitable for enteral drug administration.
• Have any other conditions or illnesses which, in the investigator's judgment, makes them unsuitable for participation in this study, , including but not limited to; • Women who are breast feeding or planning to donate eggs within 6 months after the end of the study treatment • History of hypersensitivity to compounds related to lisaftoclax or AZA or to any of their excipients • History of bleeding disorders or active uncontrolled coagulopathy.

Lab values

• Any of the following cardiac abnormalities (as determined by the study physician based on clinical examination assessments): - Any history of myocardial infarction within 6 months - Congestive heart failure (CHF) (New York Heart Association [NYHA] Class III or IV) or left ventricular ejection fraction (LVEF) < 40% - Symptomatic ventricular arrhythmia uncontrolled by medication - Any history of familial long QT syndrome - The mean QT interval calculated from 3 electrocardiogram (ECG) readings (1 to 3 minutes apart) is > 470 (Using Fridercia's correction: QTcF = QT/RR0.33)

• Aged ≥ 18 years old.
• Newly Diagnosed MDS is defined according to 2022 World Health Organization classification (5th Edition)
• Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2.
• Life expectancy ≥ 3 months.
• Able to receive oral medication.
• Adequate organ functions as defined below: - Creatinine clearance ≥ 30 ml/min (calculated with Cockcroft formula, as shown in Annex 3) - Total bilirubin < 1.5 × ULN (except Gilbert's syndrome, hyperbilirubinemia due to regular blood transfusions as assessed by the investigator) - Aspartate aminotransferase (ALT) and alanine aminotransferase (AST) ≤ 2.5 × ULN
• Negative urine or serum pregnancy test prior to dosing in women of childbearing potential. Women of childbearing potential (postmenopausal women must have been postmenopausal for at least 12 months to be considered of non-childbearing potential) and their partners are willing to use contraception as deemed effective by the investigator during treatment and for at least 6 months after the last dose of study drug.
• Subjects must have the ability to understand and voluntarily sign a written informed consent form that must be signed prior to performing any trial-specific study procedures.
• Subjects must be willing to participate in the study and are able to complete study procedures and follow-up examinations.