BY002 IIT Study in R/R Acute Leukemia

Inclusion Criteria: * Age ≥16 years. * Confirmed diagnosis of AML, ALL, or MPAL per WHO 2022 criteria. * Relapsed or refractory disease after ≥1 prior therapy. * Presence of KMT2A rearrangement or NPM1 mutation (preferred, but not exclusive). * ECOG performance status 0-2. * Adequate organ function: * ANC ≥1.0 × 10⁹/L (unless cytopenia due to leukemia) * Platelets ≥50 × 10⁹/L (unless due to leukemia) * ALT/AST ≤2.5 × ULN, bilirubin ≤1.5 × ULN * Creatinine clearance ≥50 mL/min * Negative pregnancy test for women of childbearing potential. * Willing to use effective contraception during study and 90 days after last dose. * Signed informed consent. Exclusion Criteria: * Active central nervous system (CNS) leukemia. (Prior CNS involvement allowed if treated and controlled; CNS prophylaxis permitted.) * History of significant liver disease, including viral hepatitis or cirrhosis: * HBsAg positive must have negative HBV DNA. * HCV antibody positive must have negative HCV RNA. * Known HIV infection. * Pregnant or breastfeeding women. * Significant cardiac disease: * Congenital long QT syndrome or QTcF \>450 msec. * Acute myocardial infarction, unstable angina, or coronary artery bypass within 6 months. * Congestive heart failure ≥ NYHA class II. * History of another malignancy within 5 years, except adequately treated basal cell carcinoma of the skin, in-situ breast cancer, or in-situ cervical cancer. * Autologous HSCT or CAR-T therapy within 60 days, or unresolved toxicities from ASCT/CAR-T. * Allogeneic HSCT within 100 days, or active GVHD, or requiring ongoing immunosuppressive therapy. * Anti-leukemia therapy within 2 weeks before study entry (hydroxyurea permitted). * Prior investigational drug use: \<2 weeks or \<5 half-lives for small molecules; \<4 weeks or \<5 half-lives for biologics (whichever is shorter). * Unresolved toxicities \> grade 1 from prior anti-leukemia therapy (except alopecia). * Uncontrolled active infection: * Mild infections manageable with oral/topical treatment are allowed. * Serious infections requiring hospitalization/IV antibiotics within 14 days excluded, unless resolved. * Febrile neutropenia without infection evidence may be eligible if afebrile \>72 h without antipyretics. * Active tuberculosis excluded. * Conditions impairing oral intake or absorption (e.g., swallowing difficulty, short bowel syndrome, gastroparesis). * Known severe allergy to Menin inhibitors or any component of BY002. * Investigator judges poor compliance or inability to complete study. * Any other serious disease, abnormality, or condition that may increase risk, interfere with study drug, confound results, or expected survival ≤6 months.