Study in Pediatrics With Relapsed or Refractory Pediatric Acute Lymphoblastic Leukemia (pALL) or Lymphoblastic Lymphoma

Exclusion Criteria

• •1. Concurrent enrollment in another clinical study for cancer treatment, unless the subject is in the follow-up period from a previous study.
• •2. Isolated testicular or CNS ALL
• •3. Participants with mixed-lineage leukemia (MLL) gene rearrangement
• •4. Inadequate Hepatic function
• •5. Inadequate Renal function
• •6. Radiologically-detected CNS lymphoma
• •7. Participants with clear laboratory or clinical evidence of disseminated intravascular coagulation (DIC)
• •8. Hyperleukocytosis or rapidly progressive disease that would compromise ability to complete study therapy
• •9. QT interval corrected using Fridericia's formula (QTcF) greater than or equal to a Grade 2, confirmed by 2 additional seperate electrocardiographs (ECG's) within 28 days prior to starting study drug. The initial screening ECG need not be repeated for confirmation if the QTcF interval is \<481 milliseconds.
• •10. Pregnant or breast-feeding females
• •11. Prior treatment with CAT-3888 (BL22), moxetumomab pasudotox, or any pseudomonas-exotoxin-containing compound
• •12. Prior treatment with any anticancer biologic therapy within 2 weeks prior to starting study drug, including but not limited to therapeutic monoclonal antibodies or antibody-drug conjugates
• •13. Systemic chemotherapy ≤ 2 weeks (6 weeks for nitrosoureas) and radiation therapy ≤ 3 weeks prior to starting study drug
• •14. Clinically significant ophthalmologic findings (evidence of retinal damage or injury) during the screening
• •15. Presence of a second invasive malignancy
• •16. Uncontrolled pulmonary infection, presence of pulmonary edema
• •17. Serum albumin \< 2 gram per deciliter (g/dL). Albumin infusions for correction of hypoalbuminemia are allowed, but cannot have administered within 7 days prior to start of study drug
• •18. Radioimmunotherapy within 2 years prior to study start of study drug
• •19. Participants with prior history of thrombotic microangiopathy or hemolytic uremic syndrome (HUS)
• •20. T-cell ALL or T-cell lymphoblastic lymphoma
• •21. Participants currently receiving high-dose estrogen therapy defined as \>0.625 milligram per day (mg/day) of an estrogen compound or within 2 weeks prior to starting study drug.