Study of VIP943 in Subjects With Advanced CD123+ Hematologic Malignancies

Inclusion Criteria: * Histologically confirmed AML, B-ALL or MDS. Subjects must have exhausted all available standard therapies or be deemed ineligible for potential available therapies. * Evidence of ≥5% bone marrow or blood blasts (acute leukemia) or ≥5% bone marrow or blood myeloblasts (MDS) to allow for assessment of drug activity. * Evidence of CD123 expression from a local laboratory. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 Exclusion Criteria: * Known central nervous system (CNS) metastases and/or carcinomatous meningitis. * Clinically significant cardiac disease including congestive heart failure \> New York Heart Association (NYHA) Class II), evidence for coronary artery disease (eg, unstable angina (anginal symptoms at rest) or new-onset angina (within the last 6 months or myocardial infarction within the past 6 months before first dose.