A Study of Treatment-free Remission in Chronic Phase Chronic Myeloid Leukemia

Inclusion Criteria: 1. 19 year or older 2. CP-CML patients who are taking current TKIs (imatinib, nilotinib or dasatinib) for 5 years or more 3. Patients who have failed maintaining MR3.0 after 1 or more cessation trial of TKIs. 4. Patients who regained MR3.0 or deeper molecular response by TKIs retrial after TKI cessation failure at the time of screening 5. Taking TKIs over 12 weeks for the retrial of TKIs after TKI cessation failure 6. Patients who agree with stopping asciminib and TKIs after maintaining 23 year-duration of MR4.5 7. Adequate end organ function as defined by: * Total bilirubin (TBL) \< 3 x upper limit of normal (ULN); patients with Gilbert's syndrome may only be included if TBL ≤ 3.0 x ULN or direct bilirubin ≤ 1.5 x ULN * Creatinine clearance (ClCr) ≥ 30 mL/min as calculated using Cockcroft-Gault formula * Serum lipase ≤ 1.5 x ULN. For serum lipase \> ULN - ≤ 1.5 x ULN, value must be considered not clinically significant and not associated with risk factors for acute pancreatitis 8. Patients who can sign the informed consent of their own free will Exclusion Criteria: 1. Patients who experienced grade 3 or higher adverse events with TKIs (imatinib, dasatinib, and nilotinib). 2. Patients who are receiving any other investigational agents. 3. Patients who currently have uncontrolled infections 4. Patients who previously received Chimeric antigen receptor T-cell (CAR-T cell) therapy, allogeneic hematopoietic stem cell transplantation (allo-HSCT) or biologic therapy. 5. Patients with clinically significant cardiovascular disease or gastrointestinal dysfunction. 6. Patients who have a history of thromboembolic episodes within 3 months prior to the study enrollment. 7. Patients with active hepatitis B or C with uncontrolled disease activity. 8. Patients who have active malignancies requiring treatment other than CML. 9. Patients with any severe and/or uncontrolled medical conditions or other conditions that could adversely impact on patients' ability to participate in the study. 10. Patients with psychiatric illness/social situations that would limit compliance with study requirements. 11. Pregnant women are excluded from this study Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with asciminib and TKIs, breastfeeding should be discontinued if the mother is treated with asciminib and TKIs.