Study to Determine the Dose and Safety of Asciminib in Pediatric Patients With Chronic Myeloid Leukemia

Inclusion Criteria:

• Male or female participants: Pediatric formulation group: ≥ 1 and less than 18 years of age at study entry. Adult formulation group: ≥ 14 and less than 18 years of age and body weight of ≥ 40 kg at study entry.

• Participants with Ph+ CML-CP must meet all of the following laboratory values at thescreening visit. In the case where bone marrow blast and promyelocyte counts areavailable, these will be accepted if done within 56 days prior to the screeningvisit, to avoid unnecessary repetition of this test.

1. < 15% blasts in peripheral blood and bone marrow

2. < 30% combined blasts plus promyelocytes in peripheral blood and bone marrow

3. < 20% basophils in the peripheral blood

4. Neutrophils ≥ 1.5 x 10^9/L (or WBC ≥ 3 x 10^9/L if neutrophils are notavailable) and platelet count ≥ 100 x 10^9/L

5. No evidence of extramedullary leukemic involvement, with the exception ofhepatosplenomegaly

• Prior treatment with a minimum of one TKI

• Failure (adapted from the 2020 European Leukemia Net (ELN) Guidelines Hochhaus et al 2020 and 2013 ELN Guidelines Baccarani et al 2013) or intolerance to the most recentTKI therapy at the time of screening.

• Performance status: Karnofsky ≥ 50% for patients ≥ 16 years of age, and Lansky ≥ 50for patients < 16 years of age at the time of screening

• Participants must have adequate renal, hepatic, pancreatic and cardiac function

• Participants must have electrolyte values within normal limits or corrected to bewithin normal limits with supplements prior to first dose of study medication:

• Evidence of typical BCR-ABL1 transcript [e14a2 and/or e13a2] at the time ofscreening which are amenable to standardized RQ-PCR quantification.

Exclusion Criteria:

• Known presence of the T315I mutation prior to study entry or a BCR::ABL mutationwith known resistance to study treatment any time prior to study entry.

• Known second chronic phase of CML after previous progression to AP/BC.

• Previous treatment with a hematopoietic stem-cell transplantation.

• Patient planning to undergo allogeneic hematopoietic stem cell transplantation.

• Cardiac or cardiac repolarization abnormality

• Severe and/or uncontrolled concurrent medical disease that in the opinion of theInvestigator could cause unacceptable safety risks or compromise compliance with theprotocol

• History of acute pancreatitis within 1 year of study entry or past medical historyof chronic pancreatitis.

• History of acute or chronic liver disease.

• Impairment of gastrointestinal (GI) function or GI disease that may significantlyalter the absorption of study drug

• Pregnant or nursing (lactating) females.

Other protocol-defined inclusion/exclusion may apply.