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).

A separate cohort on this study will enroll participants with r/r ABL-class Ph-like 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:

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

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).