A Phase II multicenter, open-label, single-arm dose escalation study of Asciminib monotherapy in 2nd and 1st Line Chronic Phase – Chronic Myelogenous Leukemia (ASC2ESCALATE)

Key Inclusion Criteria: Participants eligible for inclusion in this study must meet the following criteria: Criteria #1-5 are common to both patient cohorts (2L and 1L): 1. Signed informed consent must be obtained prior to participation in the study 2. CML-CP, no previous AP or BC 3. ≥ 18 years of age 4. ECOG performance status of 0, 1 or 2 5. Adequate end organ function within 14 days before the first dose of asciminib treatment. Patients with mild to moderate renal and hepatic impairment are eligible if:
*  Total bilirubin ≤ 3.0 x ULN without AST/ALT increase
*  Aspartate transaminase (AST) ≤ 5.0 x ULN
*  Alanine transaminase (ALT) ≤ 5.0 x ULN
*  Serum lipase ≤ 1.5 x ULN. For serum lipase \> ULN and ≤ 1.5 x ULN, value should be considered not clinically significant and not associated with risk factors for acute pancreatitis
*  Alkaline phosphatase ≤ 2.5 x ULN
*  Creatinine clearance ≥ 30 mL/min as calculated using Cockcroft- Gault formula Criteria #6 and 7 are specific to the 2L patient cohort. These are meant to be either/or. It is not required to have both criteria satisfied. 6. Warning or failure (according to 2020 ELN Recommendations; Hochhaus et al) to 1L TKI therapy at the time of screening a. Warning is defined as: i. Six months after the initiation of treatment: BCR::ABL1IS \>1-10% ii. Twelve months after the initiation of treatment: BCR::ABL1IS \>0.1-1% b. Treatment failure/resistance to 1L TKI is defined as: i. BCR::ABL1IS \>10% if 1L treatment duration between 6 and 12 months ii. BCR::ABL1IS \>1% if 1L treatment longer than 12 months treatment iii. Beyond 12 months after initiation of treatment: loss of MMR 7. Treatment intolerance to 1L TKI, 1. BCR::ABL1IS \> 0.1% at screening 2. Intolerance is defined as: i. Non-hematologic intolerance: Patients with grade 3 or 4 toxicity while on therapy, or with persistent grade 2 toxicity, unresponsive to optimal management, including dose adjustments (unless dose reduction is not considered in the best interest of the patient if response is already suboptimal) ii. Hematologic intolerance: Patients with grade 3 or 4 toxicity (absolute neutrophil count \[ANC\] or platelets) while on therapy that is recurrent after dose reduction to the lowest doses recommended by manufacturer Criteria #8 is specific to the 1L patient cohort 8. Patients with newly diagnosed CML-CP (treatment with a prior TKI (imatinib, or nilotinib, or dasatinib or bosutinib) for ≤ 4 weeks is allowed)

Key Exclusion Criteria: 1. Previous treatment 1. With 2 or more ATP-binding site TKIs (for 2L patient cohort) 2. More than 4 weeks with 1-ATP-binding site TKIs (for 1L patient cohort) 2. Previous treatment with asciminib 3. Known presence of the T315I mutation at any time prior to study entry 4. Known second chronic phase of CML after previous progression to AP/BC 5. Previous treatment with a hematopoietic stem-cell transplantation 6. Patient planning to undergo allogeneic hematopoietic stem cell transplantation 7. Cardiac or cardiac repolarization abnormality, including any of the following:
*  History within 6 months prior to starting study treatment of myocardial infarction (MI), angina pectoris, coronary artery bypass graft (CABG)
*  Clinically significant cardiac arrhythmias (e.g., ventricular tachycardia), complete left bundle branch block, high-grade AV block (e.g., bifascicular block, Mobitz type II and third degree AV block)
*  QTcF at screening ≥450 msec (male patients), ≥450 msec (female patients)
*  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 (TdP) 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" per www.crediblemeds.org that cannot be discontinued or replaced 7 days prior to starting study drug by safe alternative medication
*  Inability to determine the QTcF interval 8. History of acute pancreatitis within 1 year of study entry or past medical history of chronic pancreatitis 9. Participation in a prior investigational study within 30 days prior to enrollment or within 5 half-lives of the investigational product, whichever is longer 10. Treatment with medications that meet one of the following criteria is not allowed and should be switched to an alternative at least one week prior to the start of treatment with study treatment:
*  Strong inducers of CYP3A for patients on the dose of 80 mg QD and 200mg QD
*  Strong inducers and inhibitors of CYP3A for patients on the dose of 200 mg BID 11. Pregnant or nursing (lactating) women 12. Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they are using highly effective methods of contraception. Highly effective contraception for women should be maintained throughout the study and for at least 7 days after the last dose. 13. Sexually active males unwilling to use a condom during intercourse while taking study treatment and for 7 days after stopping study (only for patients treated with asciminib). 14. 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 (e.g. uncontrolled diabetes, active or uncontrolled infection; uncontrolled arterial or pulmonary hypertension, uncontrolled clinically significant hyperlipidemia). 15. History of other active malignancy within 3 years prior to study entry with the exception of previous or concomitant basal cell skin cancer and previous carcinoma in situ treated curatively. 16. Known hypersensitivity to the study treatment.