A Study to Evaluate HMPL-306 in Patients With IDH1or IDH2-mutated Acute Myeloid Leukemia

Inclusion Criteria:

1. Have signed the ICF;
2. Be able to follow the requirements of study protocol;
3. Age ≥18 years;
4. Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0 to 2;
5. Cohort 1: Patients with R/R primary AML harboring IDH1-R132 site mutation \[WHO 2022 Classification Criteria for Myeloid Neoplasms and Acute Leukemia, with the exception of APL (AML-M3) and extramedullary recurrence of leukemia alone without bone marrow involvement\]; Cohort 2: Patients with R/R primary AML harboring IDH2-R140/R172 mutations \[WHO 2022 Classification Criteria for Myeloid Neoplasms and Acute Leukemia, with the exception of APL (AML-M3) and recurrence of extramedullary leukemia alone without bone marrow involvement\]. A patient with both IDH1 and IDH2 mutations will be included in Cohort 2 (IDH2 mutation group);
6. Agree to undergo bone marrow aspiration and/or biopsy before and during treatment;
7. Be willing to complete QoL assessments at specified time points during study treatment and after treatment discontinuation;
8. Female patients of childbearing potential must agree to use highly effective contraceptive methods during the study and within 30 days after discontinuation of the study drug (the time limit of contraception for the chemotherapy group needs to be extended to 6 months after the last dose) (see Appendix 9 (contraception requirements) for more information), and agree not to donate eggs (oocytes) for reproductive purposes during this period; patients must not be lactating and must have a negative pregnancy test (if of childbearing potential);
9. Male patients with female partners of childbearing potential must use condoms during intercourse and avoid donating or freezing sperm during the study and within 30 days after discontinuation of the study drug (the time limit of contraception for the chemotherapy group needs to be extended to 6 months after the last dose).
10. Predicted survival greater than 12 weeks as assessed by the investigator.

Exclusion Criteria:

Patients who meet any of the following criteria must be excluded:

1. Patients who received prior treatment with IDH1 inhibitors, IDH2 inhibitors, or IDH1/IDH2 dual target inhibitors;
2. Patients with known RAS or FLT3 hotspot mutations (patients who have test results definitely switched to negative at the time of enrollment can be enrolled);

   Hotspot mutations include:

   KRAS mutations: G12 or G13 (exon 2); Q61 (exon 3) NRAS mutations: G12 or G13 (exon 2); Q61 (exon 3) FLT3 mutations: ITD; TKD (D835 or I836)
3. Inadequate organ function, as defined below:

   * Serum total bilirubin (TBIL) higher than 1.5 times the upper limit of normal (ULN), excluding the following patients:

     \- Patients with Gilbert's disease, with normal alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and serum TBIL ≤ 3 × ULN.
   * AST or ALT \> 2.5 × ULN (if leukemia invades the liver, patients with AST and ALT levels ≤ 5 × ULN can be enrolled);
   * Estimated creatinine clearance by Cockcroft-Gault formula \< 50 mL/min or creatinine \> 1.5 × ULN;
4. International Normalized Ratio (INR) \> 1.5 × ULN or activated partial thromboplastin time (aPTT) \> 1.5 × ULN, except for patients who are receiving anticoagulant therapy;
5. Blood amylase \> 1.5 × ULN and assessed to be clinically significant by the investigator;
6. Current known history of liver disease, including cirrhosis, alcoholic liver disease, active infection with hepatitis B virus (HBV) or hepatitis C virus (HCV):

   * Patients who are positive for serum hepatitis B surface antigen (HBsAg) and/or hepatitis B core antibody (HBcAb) are required to undergo HBV deoxyribonucleic acid (DNA) testing, and patients with HBV DNA test results that are either negative or below the lower limit of normal at the site can be enrolled;
   * Patients with positive HCV serology may be enrolled only if the HCV ribonucleic acid (RNA) test is negative or below the lower limit of normal at the site;
7. Known human immunodeficiency virus (HIV) infection;
8. Meet any of the following cardiac function-related criteria:

   * Any clinically significant rhythm or conduction abnormalities requiring clinical intervention;
   * Clinically significant cardiovascular diseases that require clinical intervention as judged by the investigator, including but not limited to: acute myocardial infarction, unstable angina pectoris, coronary artery bypass grafting within 6 months prior to randomization, New York Heart Association (NYHA) Class II (inclusive) or above congestive heart failure, left ventricular ejection fraction (LVEF) \< 45%, or uncontrolled hypertension after medication (systolic blood pressure \> 160 mmHg or diastolic blood pressure \> 100 mmHg);
   * Congenital long QT syndrome or QTcF \>470 msec in females/QTcF \>450 msec in males;
   * Use of drugs currently known to cause QT prolongation (Appendix 5); patients who have switched the medication by 5 half-lives of the drug prior to the dosing of the study drug or have their ECG to be regularly monitored during the study (QTcF is required to be regularly monitored if no medication is available for replacement) could be enrolled.
9. Patients with other primary malignancies within the last 5 years, except for patients who have been cured, and patients with the following non-invasive tumors who have been treated with definitive treatment:

   * Basal cell carcinoma of skin
   * Squamous cell carcinoma of skin and cervix
   * Carcinoma in situ of cervix
   * Breast cancer in situ
10. Pregnant (positive pregnancy test prior to treatment) or lactating women;
11. Patients with childbearing requirements;
12. History of stroke or intracranial hemorrhage within 6 months prior to randomization;
13. Patients who have undergone major surgery within 4 weeks prior to randomization;
14. Patients who have received any monoclonal antibody for anti-tumor therapy within 3 weeks or 2 half-lives prior to randomization, whichever is longer;
15. Patients who have received treatment with the investigational product or investigational device in a clinical study within 3 weeks prior to randomization;
16. Patients who have received anti-tumor treatment (chemotherapy, targeted therapy, immunotherapy, or anti-tumor vaccine, etc,) within 3 weeks prior to randomization or received radiotherapy within 3 months prior to randomization; patients who have received CAR-T therapy within 4 weeks prior to randomization; patients who have received HSCT within 60 days prior to randomization, or are receiving immunosuppressive therapy after HSCT at screening, or are accompanied by graft-versus-host disease (GVHD) requiring drug control; patients undergoing treatment for skin graft-versus-host disease (GVHD) with fixed oral doses of and/or topical corticosteroids may be enrolled only if they can benefit from the study treatment as assessed by the investigator; for patients receiving prophylactic intrathecal administration of chemotherapy drugs (cytarabine, dexamethasone and methotrexate) to prevent central leukemia, no washout is required;
17. Central nervous system leukemia: patients with clinical symptoms suggesting active central nervous system (CNS) leukemia or confirmed CNS leukemia invasion;
18. Patients who have received live vaccines within 4 weeks prior to randomization;
19. Use of traditional Chinese medicine with anti-tumor effect within 1 week prior to randomization;
20. Patients with uncontrolled active systemic fungal, bacterial, or viral infection (defined as persistent signs/symptoms related to the infection without improvement despite appropriate antibiotic or antiviral therapy and/or other treatments), or persistent unexplained pyrexia (\> 38.5℃) without improvement during the screening period (only patients with tumor fever as judged by the investigator can be enrolled);
21. Inability to take medications orally, past surgery history or severe gastrointestinal diseases including dysphagia, active gastric ulcer, etc., which may interfere with the absorption of study drug as judged by the investigator;
22. Insufficient compliance in participating in this clinical study as judged by the investigator;
23. Toxicities from previous anti-tumor treatments have not yet recovered to Grade ≤ 1 (excluding alopecia);
24. Patients with any other disease, metabolic abnormality, physical examination abnormality or clinically significant laboratory test abnormality, based on which the investigator has reason to suspect that the patient has certain disease or condition that is not suitable for treatment with the investigational product, or that will affect the interpretation of study results or will put the patient at high risk.