Open-label Study of IMGN779 in Adult Patients With Relapsed/Refractory CD33-positive Acute Myeloid Leukemia

Inclusion Criteria: * Dose Escalation: Patients with relapsed or refractory AML * Dose Expansion: Patients with relapsed AML or patients who refuse, or are not suitable candidates for induction therapy Exclusion Criteria: * Dose Escalation: Acute Promyelocytic Leukemia * Any concurrent anti-cancer therapy including chemotherapy, immunotherapy, radiotherapy, biologic or any investigational agents (with the exception of hydroxyurea or leukapheresis for control of hyperleukocytosis) within 14 days or five half-lives of drugs, whichever is shorter, prior to Cycle 1 Day 1 * AML patients with known, active leptomeningeal/central nervous system (CNS) involvement * Prior treatment with IMGN779 * Women who are pregnant or breast feeding