A DLT is defined as any of the following events, except those that are clearly due to underlying disease or extraneous causes: A hematologic DLT is defined as: * CTCAE Grade 3 or 4 febrile neutropenia or neutropenic infection. * CTCAE Grade 4 neutropenia lasting \>7 days. * CTCAE Grade 4 thrombocytopenia. * CTCAE Grade 3 thrombocytopenia with clinically significant bleeding, or Grade 3 thrombocytopenia requiring a platelet transfusion. * CTCAE Grade 4 anemia. A non-hematologic DLT is defined as: * CTCAE Grade 4 tumor lysis syndrome (TLS). Grade 3 TLS will not constitute DLT unless it leads to irreversible end-organ damage. * CTCAE Grade 3 or higher AE (including nausea, vomiting, diarrhea, and electrolyte imbalances lasting more than 48 hours despite optimal therapy; excluding all grades of alopecia). * CTCAE Grade 3 or higher hypersensitivity reaction (regardless of premedication). * CTCAE Grade 2 or higher skin ulceration.

The recommended dose was established by the dose escalation steering committee and based on safety findings during Part 1 of the study.

An adverse event (AE) is defined as any untoward medical occurrence in a participants enrolled into this study regardless of its causal relationship to study drug. A TEAE is defined as any event not present before exposure to study drug or any event already present that worsens in either intensity or frequency after exposure to study drug.

An adverse event (AE) is defined as any untoward medical occurrence in a participant enrolled into this study regardless of its causal relationship to study drug. A treatment emergent AE (TEAE) is defined as any event not present before exposure to study drug or any event already present that worsens in either intensity or frequency after exposure to study drug. An SAE is defined as any event that results in death, is immediately life-threatening, requires inpatient hospitalization or prolongation of existing hospitalization, results in persistent or significant disability/incapacity, or is a congenital anomaly/birth defect.