An Open Label, Randomized (2:1) Phase IIb Study of Dasatinib Versus Imatinib in Patients With Chronic Phase Chronic Myeloid Leukemia Who Have Not Achieved an Optimal Response to 3 Months of Therapy With 400 mg Imatinib

Inclusion Criteria:

- CP-CML Philadelphia chromosome positive (Ph+) patients with CHR but with BCR-ABL
level > 10% IS after 3 months of Imatinib 400 mg treatment. Imatinib monotherapy must
have been started within 3 months of CP-CML diagnosis

- Currently tolerating Imatinib 400 mg QD

- Eastern Co-Operative Group (ECOG) performance status = 0 - 2

- Adequate renal function defined as serum creatinine ≤ 3 times the institutional upper
limit of normal (ULN)

- Adequate hepatic function defined as:

- Total Bilirubin ≤ 2.0 times institutional ULN

- Alanine Aminotransferase (ALT) ≤ 2.5 times the institutional ULN

- Aspartate Aminotransferase (AST) ≤ 2.5 times the institutional ULN

- Serum Na, K, Mg, and total serum Ca or ionized Ca levels must be greater than or
equal to the institutional lower limit of normal

Exclusion Criteria:

- Accelerated Phase (AP)/ blast crisis (BP) diagnosis

- Not in Complete Hematologic Response (CHR) by 3 month

- Documented T315I mutation

- Prior Chronic Myeloid Leukemia (CML) treatment other than Imatinib

- Serious, uncontrolled Medical condition