Study of AZD0466 Monotherapy or in Combination in Patients With Advanced Haematological Malignancies

Inclusion Criteria: * Diagnosis of acute myeloid leukaemia (AML) or acute lymphoblastic leukaemia (ALL), or intermediate or higher risk myelodysplastic syndrome (MDS; Part A only), which is histologically proven based on criteria established by the World Health Organization (WHO) as documented by medical records. for which there are limited treatment options known to provide clinical benefit. * Eastern cooperative oncology group performance status ≤2. Performance status must not have deteriorated by ≥2 levels within 2 weeks after providing informed consent. * Predicted life expectancy ≥8 weeks. * Adequate organ function at screening as per the protocol defined criteria. * Adequate cardiac function as demonstrated by LVEF \> 50% on screening cardiac multigated acquisition, magnetic resonance image or echocardiogram. * Willing and able to participate in all required study evaluations and procedures including receiving IV administration of study treatment and admission to the hospital, when required, for administration of study treatment and monitoring. * For inclusion in the genetic component of the study, participants must fulfil protocol defined criteria. * White blood cell count must be \<10 x 10\^9/L prior to the first dose in Cycle 1, Day 1. Treatment with hydroxyurea during screening and Cycle 1 to control white blood cell count is permitted. * Women of childbearing potential and men should use protocol defined contraceptive measures. Exclusion Criteria: * Unresolved t…