Treatment Optimization for Patients With Chronic Myeloid Leukemia (CML) With Treatment naïve Disease (1st Line) and Patients With Resistance or Intolerance Against Alternative Abl-Kinase Inhibitors (≥2nd Line)

Dasatinib is indicated in Europe for:

• Treatment of adult patients with newly diagnosed Philadelphia chromosome positive (Ph+) chronic myeloid leukemia (CML) in the chronic phase
• Chronic, accelerated or blast phase CML with resistance or intolerance to prior therapy including imatinib
• Ph+ acute lymphoblastic leukemia (ALL) and lymphoid blast CML with resistance or intolerance to prior therapy Compared to imatinib, dasatinib in CML achieves faster and better responses. Dasatinib is known for its selected toxicities (fluid retention, edema, pleural effusion, and hematological toxicity) requiring dose reductions or treatment interruptions; these toxicities are more frequent in the first two years of treatment. A randomized dose optimization trial for QD dosing vs. BID dosing has demonstrated non-inferiority with regards to efficacy with an improved toxicity profile. In a pilot study, analyzing patients with dasatinib toxicity, a fixed dasatinib weekend holiday allowed safe toxicity management without impairing efficacy. Furthermore the alternated schedule was also able to improve response parameters in patients that had never achieved an acceptable response prior to the onset of dasatinib holiday dosing schedule. The biological rationale for a holiday dosing schedule is that dasatinib has shown an improved cell death of CML cells even after short exposure times; this improved cell death exceeds the killing rate observed with imatinib in vitro. In summary, the reported preclinical and clinical evidence indicates that efficacy seems to require adequate dasatinib Cmax, while low Cmin (five half-lives between doses) does not impair efficacy nor induces drug resistance. It is speculated that a weekend holiday, allowing a better tolerability, would improve patients' drug adherence. The Investigators hypothesize that a dasatinib holiday schedule (5x100mg+2x0mg weekly) compared to a regular dose (7x100mg weekly) will reduce the rate of clinically significant toxicity (e.g., fluid retention, hematological toxicity, musculoskeletal pain) by 20% observed within the first two years of treatment. The Investigators also hypothesize that the dasatinib holiday schedule is non-inferior to dasatinib regular dose in achieving the European LeukemiaNet (ELN) recommended levels of response within the first 24 months.