Dose Escalation - Determine the maximum tolerated dose (MTD), if possible, or minimum optimal biologic dose (OBD), and evaluate the safety and tolerability of VIP943 in subjects with advanced CD123+ hematologic malignancies

Relapsed or refractory AML, MDS, or B-ALL subjects who are CD123 positive. Subjects must have exhausted all available standard therapies or be deemed ineligible for potential available therapies.

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.