Study of ORM-1153 in Acute Myeloid Leukemia (AML) With CD123 Expression

The goal of this Phase 1 clinical trial is to understand whether a new experimental treatment, called ORM-1153, will be a safe and possibly effective treatment option for participants with blood cancers such as Acute Myeloid Leukemia (AML) which have a particular protein (called Cluster of Differentiation 123 or CD123) on the cancer cell's surface. Phase 1 studies are designed to find a safe and effective dose. Participants will be receiving ORM-1153 at the defined study frequency as an infusion into the vein. They will need to visit the clinic frequently during the first few months of treatment.

Inclusion Criteria: * Adults ≥18 years of age (or ≥19 years of age according to local regulatory guidelines) at the time of signature of the informed consent form. * Documented diagnosis of relapsed or refractory AML with any detectable level of CD123 as evaluated by local assessment. * Eastern Cooperative Oncology Group (ECOG) performance status ≤2 * Adequate organ and coagulation function. Exclusion Criteria: * Diagnosed with Acute Promyelocytic Leukemia. * Systemic antineoplastic agent therapy given within 14 days or 5 half-lives prior to the first dose of ORM-1153 (whichever is shorter). * Hematopoietic Stem Cell Transplantation within 3 months of the first dose of ORM-1153. * Total White Blood Cell count \>25,000/µL.