The purpose of this Chinese bridging study is to evaluate the efficacy, safety, tolerability and pharmacokinetics of asciminib versus best available therapy in Chinese patients with Chronic Myelogenous Leukemia in chronic phase, previously treated with 2 or more tyrosine kinase inhibitors to support related indication registration in China.

The primary objective of the study is to evaluate the Major Molecular Response (MMR) rate of asciminib treatment at 24 weeks.

The purpose of this Chinese bridging study is to evaluate the efficacy, safety, tolerability and pharmacokinetics (PK) of asciminib versus best available therapy (BAT) in Chinese patients with Chronic Myelogenous Leukemia in chronic phase (CML-CP), previously treated with 2 or more tyrosine kinase inhibitors (TKIs) to support related indication registration in China.

This study will enroll the participants 1) who failed their most recent TKI therapy by meeting the definition of treatment failure as per the 2013 European Leukemia Net (ELN) guidelines, or 2) who were intolerant to the most recent TKI therapy and must have BCR-ABL1 ratio > 0.1% IS at screening.

Eligible participants will be randomized into asciminib arm or the BAT arm on a 2:1 ratio, to receive asciminib treatment (continuous 40 mg BID) or BAT from Day 1 until the end of study treatment period defined as 96 weeks after the last participant receives the first dose.

Inclusion Criteria:

Diagnosed as CML-CP:

1. Participants must meet all of the following laboratory values at the screening visit:

   < 15% blasts in peripheral blood and bone marrow < 30% blasts plus promyelocytes in peripheral blood and bone marrow < 20% basophils in the peripheral blood

   • 50 x 10^9/ L (≥ 50,000/mm3) platelets Transient prior therapy related thrombocytopenia (< 50,000/mm3 for ≤ 30 days prior to screening) is acceptable No evidence of extramedullary leukemic involvement, with the exception of hepatosplenomegaly

2. Prior treatment with a minimum of 2 prior ATP-competitive TKIs.

3. Failure (adapted from the 2013 European Leukemia Net (ELN) Guidelines) or intolerance to the most recent TKI therapy at the time of screening.

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

Exclusion Criteria:

1. Known presence of the T315I mutation at any time prior to study entry

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

3. Previous treatment with a hematopoietic stem cell transplantation

4. Participants planning to undergo allogeneic hematopoietic stem cell transplantation

5. Cardiac or cardiac repolarization abnormality, including any of the following:

   History within 6 months prior to starting study treatment of myocardial infarction, angina pectoris, coronary artery bypass graft Clinically significant cardiac arrhythmias , complete left bundle branch block, high-grade AV block QTcF at screening ≥450 msec (male participants), ≥460 msec (female participants)

   Long QT syndrome, family history of idiopathic sudden death or congenital long QT syndrome, or any of the following:

   Risk factors for Torsades de Pointes including uncorrected hypokalemia or hypomagnesemia, history of cardiac failure, or history of clinically significant/symptomatic bradycardia Concomitant medication(s) with a "Known risk of Torsades de Pointes" that cannot be discontinued or replaced 7 days prior to starting study drug by safe alternative medication.

   Inability to determine the QTcF interval

6. History of acute pancreatitis within 1 year of study entry or past medical history of chronic pancreatitis

Other protocol-defined inclusion/exclusion criteria may apply.

Novartis is committed to sharing with qualified external researchers, access to patient-level data and supporting clinical documents from eligible studies. These requests are reviewed and approved by an independent review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations.

This trial data availability is according to the criteria and process described on www.clinicalstudydatarequest.com