Eligible patients include adults (&ge;18 years) with relapsed/refractory ALL, AML, or MPAL (WHO 2016, CD71+ &ge;20% blasts), controlled blast count (<20,000/mm ³), adequate organ function, and ECOG 0-2. Exclusions cover APL, prior anti-TfR therapy, recent transplant, CNS disease, uncontrolled cardiac/liver disease, active infection, pregnancy, and major surgery within 4 weeks.

INA03 will be administered IV on Day 1, Day 14 of 28-day cycles. The administration of INA03 will begin at 0.02 mg/kg. Study Part I is a titration study to determine the dose for the first INA03 infusion. Patients will be enrolled in sequential cohorts of 2 patients to receive ascending starting doses of INA03, starting from the lowest starting dose (0.02 mg/kg), and followed by subsequent administrations of INA03 (D14 and beyond) at a fixed dose of 0.1 mg/kg. The starting dose will be increased every cohort of 2 patients until evidence of absence of marrow residual erythroblasts by D14 myelogram. This dose is referred to as the MEID and will be selected as the D1 dose for the study Part 2. Patient accumulation in Part I of the study will continue until no evidence of non-hematological DLT within 28 days post dosing

Safety is evaluated via NCI-CTCAE v5.0-graded adverse events. Pharmacokinetic analysis includes Cmax, AUC, and half-life (t½) from dosing to Day 42, while pharmacodynamics tracks erythroblast/blast reduction via bone marrow aspirates. Anti-INA03 antibodies are measured, and preliminary efficacy is assessed per ELN 2017 criteria for up to 182 days.