Safety and Efficacy of Asciminib in Pediatrics and Young Adults With Relapse/Refractory (r/r) Philadelphia Positive (Ph+) or ABL-class Ph-like Acute Lymphoblastic Leukemia (ALL)

This is a single arm phase I/II multicenter study to assess the safety and efficacy of asciminib at the RP2D in combination with low intensity chemotherapy (debulking induction) followed by asciminib plus blinatumomab (consolidation) in pediatric and young adult participants with r/r Ph+ ALL (inclusive of participants with T315I mutation).

The aim of the study design is to explore a novel treatment regimen which is expected to be more tolerable than the high intensity chemotherapy backbone-based regimens.

This study will consist of a 2-part design:

Part 1 dose escalation using a Bayesian Optimal Interval (BOIN) statistical design, and after determination of RP2D Part 2 dose expansion.

Participants will only enroll in either Part 1 or Part 2, and not both.

Both Part 1 and Part 2 (dose escalation and dose expansion) will have the following phases:

• Core Study Treatment Phase
• Survival Follow up Phase

Participants with known T315I mutation will not participate in Part 1 or Part 2. They will be part of a separate cohort.

The core study treatment phase will consist of 3 cycles of therapy: cycle 1 asciminib with low intensity chemotherapy (debulking induction), followed by cycle 2 (blinatumomab-block 1 with asciminib) and cycle 3 (blinatumomab-block 2 with asciminib).

Inclusion criteria

• Evidence of Ph+ ALL or ABL1 or ABL2 fusion Ph-like ALL, inclusive of participants with ABL1 T315I mutation
• Participants with CNS1, CNS2, CNS3a, or CNS3b at screening
• Active B-Cell ALL at screening defined by MFC or IG/TCR PCR of ALL blasts >0.01% in participants with either:

• Primary refractory disease (>0.01% ALL blasts present at the end of consolidation) OR
• Relapsed ALL with evidence of involvement of BM with ALL (MFC or IG/TCR PCR >0.01%) after at least one line of therapy
• Documented history of CD19 expressing B-cell ALL (in peripheral blood or bone marrow by flow cytometry).

a) For participants who received anti-CD19 targeted therapy (e.g CD19 CAR T cells or blinatumomab), CD19 expressing B-cell ALL must be documented after anti-CD19 therapy completion prior to cycle 1 day 1

• Adequate hepatic and renal function (local laboratory analysis) as defined:

• ALT ≤ 5x upper limit of normal (ULN) for age
• Total bilirubin (sum of conjugated + unconjugated) ≤ 1.5 x ULN) for age, except for participants with Gilbert's syndrome who may only be included if total bilirubin ≤ 3.0 x ULN or direct bilirubin ≤ 1.5 x ULN
• Estimated glomerular filtration rate (eGFR) using the Cockcroft-Gault formula in participants ≥ 18 years, OR radioisotope GFR ≥50 mL/min/1.73 m^2, OR creatinine based on age and sex for participants < 18 years old
• Adequate cardiac function defined as shortening fraction ≥27% by echocardiogram (ECHO) OR left ventricular ejection fraction of ≥50% by ECHO

Exclusion criteria

• Participants with >3 relapses of ALL
• Extramedullary disease (non-CNS and/or isolated CNS disease)
• Participants with CNS3c (Clinical signs of CNS leukemia (such as facial nerve palsy, brain/eye involvement or hypothalamic syndrome))
• Cardiac or cardiac repolarization abnormality, including but not limited to clinically significant cardiac arrhythmias, long QT syndrome, family history of idiopathic sudden death or congenital long QT syndrome or other clinically significant heart disease (e.g., congestive heart failure, etc.)
• Severe and/or uncontrolled concurrent medical disease that in the opinion of the investigator could cause unacceptable safety risks or compromise compliance with the protocol.

Other protocol defined inclusion/exclusion criteria may apply.