This study is designed to evaluate the safety, tolerability, and preliminary estimate of antitumor activity of SGN-CD123A. The study will be conducted in 2 parts:~Part A is the dose-escalation portion of the trial, designed to identify the maximum tolerated dose (MTD) of SGN-CD123A~Part B is the dose-expansion portion of the trial, designed to evaluate SGN-CD123A in patients with differing CD123 expression levels~Dose-escalation in Part A will be conducted using a 3+3 study design. Patients with CD123-detectable AML will be enrolled in cohorts at escalating doses of study drug and will receive up to 2 induction cycles of SGN-CD123A treatment at an assigned dose level in 3-week cycles.~After completion of dose-escalation, patients will be enrolled in Part B of the study. Patients enrolled in Part B will receive up to 2 induction cycles of SGN-CD123A treatment at a dose level and frequency determined by results in Part A.~For both Part A and Part B, a third induction cycle may be permitted with the approval of the study medical monitor. If a patient achieves a complete remission or complete remission with incomplete hematologic recovery, optional post-remission cycles of SGN-CD123A may be administered.
The study will examine the safety profile of SGN-CD123A. The study will test increasing doses of SGN-CD123A given every 3 weeks to patients.