Study of Carfilzomib in Combination With Induction Chemotherapy in Children With Relapsed or Refractory Acute Lymphoblastic Leukemia

Phase 1b Key Inclusion Criteria:

• Age 21 years or younger at the time of initial ALL diagnosis and age > 1 year at the time of study treatment initiation.
• Subjects must have a diagnosis of relapsed or refractory ALL with ≥ 5% blasts in the bone marrow (M2 or M3 disease), with or without extramedullary disease.

-To be eligible, subjects must have had 1 or more prior therapeutic attempts, defined as:

• Early first relapse ( 1.5 × ULN, the subject must have a calculated creatinine clearance or radioisotope glomerular filtration rate (GFR) ≥ 70 mL/min/1.73 m2.
• Adequate liver function, defined as both of the following:
• Total bilirubin ≤ 1.5 × institutional ULN except in the presence of Gilbert Syndrome
• Alanine aminotransferase (ALT) ≤ 5 × institutional ULN
• Performance status: Karnofsky or Lansky scores ≥ 50 for subjects > 16 years old or ≤ 16 years old, respectively.

Phase 2 Inclusion Criteria:

• Subject's legally acceptable representative has provided informed consent when the subject is legally too young to provide informed consent and the subject has provided written assent based on local regulations and/or guidelines prior to any study-specific activities/procedures being initiated, except for standard of care local testing as permitted per protocol.
• Age greater than or equal to 1 month to less than 21 years. Subjects greater than or equal to 18 years must have had their original diagnosis at less than 18 years of age.
• Subjects must be diagnosed with relapsed or refractory relapsed ALL.
• Subjects must have a documented first remission, less than 5% blasts in the bone marrow (M1 bone marrow) and no evidence of extramedullary disease.
• T-cell ALL with bone marrow relapse (defined as greater than or equal to 5% leukemia blasts in bone marrow) or refractory relapse with or without extramedullary disease.

OR B-cell ALL bone marrow relapse or refractory relapse (defined as greater than or equal to 5% leukemia blasts in bone marrow) after having received a targeted B-cell immune therapy (eg, blinatumomab, inotuzumab or a CAR-T therapy) with or without extramedullary disease..

• Adequate liver function: bilirubin less than or equal to 1.5 x upper limit of normal (ULN), alanine aminotransferase (ALT) less than or equal to 5 x ULN.
• Adequate renal function: serum creatinine less than or equal to 1.5 x ULN or glomerular filtration rate (GFR) greater than or equal to 70 mL/min/1.73 m^2; or for children less than 2 years of age, greater than or equal to 50 mL/min/1.73 m^2.
• Adequate cardiac function: shortening fraction greater than or equal to 30% or ejection fraction greater than or equal to 50%.
• Karnofsky (subjects greater than or equal to 16 years of age) or Lansky (subjects 12 months to less than 16 years of age) performance status greater than or equal to 50%.
• Subjects must have fully recovered from the acute toxic effects of all previous chemotherapy, immunotherapy, or radiotherapy treatment before enrollment (for example: recovery from gastrointestinal toxicity may occur more rapidly than less reversible organ toxicities such as sinusoidal obstruction syndrome or non-infectious pneumonitis, for serious prior toxicities recommended discussion with Amgen medical monitor).
• Life expectancy of greater than 6 weeks per investigator's judgement at time of screening.

Phase 1b Key Exclusion Criteria:

• Known allergy to any of the drugs used in the study (Subjects who have had a previous allergy to PEG-asparaginase and if able, may receive Erwinia asparaginase at the investigator's discretion)
• Known allergy to Captisol (a cyclodextrin derivative used to solubilize carfilzomib)
• Left ventricular fractional shortening < 30%
• History of ≥ Grade 2 pancreatitis
• Active graft-versus-host disease requiring systemic treatment
• Positive culture for or other clinical evidence of infection with bacteria or fungus within 14 days of the initiation of study treatment
• Down Syndrome
• Prior th