A Study of XY0206 Tablets in Patients With Relapsed / Refractory Acute Myeloid Leukemia

1. To evaluate the safety and tolerability of xy0206 as single drug in the treatment of relapsed / refractory AML; 2. Evaluate the dose limited toxicity (DLT) and maximum tolerable dose (MTD) of xy0206 as single drug in the treatment of relapsed / refractory AML subjects. 3. To evaluate the pharmacokinetic (PK), pharmacokinetic (PD) characteristics and PK / PD correlation of xy0206 as single drug treatment in relapsed / refractory AML subjects; 4. To evaluate the primary efficacy of xy0206 as single drug in the treatment of relapsed / refractory AML patients; 5. To evaluate biomarkers of xy0206 as single drug treatment for relapsed / refractory AML subjects.