Phase II Study Testing the Tolerability and the Efficacy of Bosutinib in Chronic Phase CML Patients

Patients will start with dose-level 1 (300 mg once daily) Bosutinib. If patients do not experience any toxicity or only G1 toxicity, they will be dose-increased first to dose-level 2 (400 mg once daily ) and then to dose-level 3 (500 mg once daily). Dose will not be escalated above 500 mg which is the dose recommended by the summary of product information. If patients experience G2 toxicity, the study drug will be further continued at the same dose-level. In patients with G3 or G4 toxicities, therapy will be withheld until toxicity resolved to \<G2.