This study is designed to confirm the efficacy of dasatinib 100mg once daily in producing a complete molecular response and to prove a possibility of "Operational Cure" in CMR patients.

This study also examines kinetics of complete molecular responses using new highly sensitive PCR based technology, digital PCR, which is reported to have a sensitivity down to 6 log reduction.

Inclusion Criteria:

• Patients must have Ph+ CML in CP
• newly diagnosed chronic phase CML, except hydroxyurea, anagrelide and within 7 days imatinib treatment
• Subjects must be enrolled in this study within approximately 3 months (90 days) after the date of first being diagnosed with CML. Subjects are allowed to have clonal chromosomal abnormalities in addition to the Philadelphia chromosome and remain eligible
• 0-2 ECOG Performance Status (PS) Score
• Adequate hepatic function test
• Adequate renal function test
• Adequate other organ functions
• Women of childbearing potential (WOCBP) must be using an adequate method of contraception to avoid pregnancy
• WOCBP must have a negative serum or urine pregnancy test (minimum sensitivity 25 IU/L or equivalent units of HCG) within 72 hours prior to the start of investigational product.
• Subjects agree to sign informed consent

Exclusion Criteria:

• WOCBP who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period and for at least one month (4 weeks) before and for at least 1 month (4 weeks) after the last dose of study medication.
• WOCBP using a prohibited contraceptive method (Not applicable for this study).
• Women who are pregnant or breastfeeding.
• Women with a positive pregnancy test at enrollment or prior to administration of study medication.
• Men whose sexual partners are WOCBP, who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study period and for at least one month (4 weeks) after completion of study medication.
• A serious uncontrolled medical disorder or active infection that would impair the ability of the subject to receive protocol therapy.
• Known pleural effusion at baseline.
• Uncontrolled or significant cardiovascular disease
• History of significant bleeding disorder unrelated to CML
• Prior chemotherapy for peripheral stem cell mobilization. (Prior collection of un-mobilized peripheral blood stem cells is permitted).
• Prior or concurrent malignancy
• Evidence of digestive dysfunction that would prevent administration of study therapy by mouth
• Uncontrolled diabetes

Newly diagnosed, CP-CML patients ≥ 18 years of age. Use of dasatinib for less than three weeks prior to study entry is allowed.

Adult patients with a molecularly confirmed diagnosis of BCR-ABL positive CML in new CP who have not been treated with any myeloablative or interferon alpha therapy.