Inclusion Criteria:  The patient signs the informed consent form Age over 18, male or female The patient was diagnosed as chronic phase of CML. ECoG score 0-2 Receive TKI treatment for at least 4 years and continuously obtain MR4 or mr4.5 for at least 3 years. The subjects fully understand and comply with the requirements of the research scheme and are willing to complete the research as planned.  Exclusion Criteria:  NA