Objectives: To evaluate the efficacy and safety of imatinib mesylate (imatinib) for patients with Philadelphia chromosome-positive (Ph+ ) chronic myeloid leukemia (CML) in accelerated and blastic phase.
Methods: Seventy-five Ph+ CML patients in accelerated phase and 49 in blastic phase were treated with 400 mg or 600 mg of imatinib once daily.
Results: For patients in accelerated phase, the cumulative hematological response (HR) rate was 93.3%, including complete HR (CHR) rate 85.3%, and returning to chronic phase (RCP) rate 8% in a median follow-up of 23.0 (1.0 -64.0 ) months. Cumulative major cytogenetic response (MCyR) rate was 33.0%, and complete cytogenetic response (CCyR) rate 28.0%. For patients with CCyR, the major molecular response (MMoR) rate was 47.6%. The estimated 4-year progression-free survival (PFS) rate and overall survival (OS) rate were 48.2% and 52.2% in patients with HR, respectively. Severe leukocytopenia, anemia and thrombocytopenia occurred in 37.3%, 34.6% and 45.3% of all patients, respectively. For patients in blastic phase, the cumulative HR rate was 63.3%, including CHR rate 44.9%, and RCP rate 18.4% in a median follow-up of 4.5 (0.3 -63.0) months. Cumulative MCyR rate and CCyR rate were both 12.2%. For patients with CCyR, the MMoR rate was 33.3%. For patients with HR, the estimated 1-year/2-year PFS and OS rates were 32.8%/15.8% and 46.0%/ 21.0% respectively. Severe leukocytopenia, anemia and thrombocytopenia occurred in 75.5%, 71.4% and 73.5% of all patients, respectively.
Conclusions: The efficiency of imatinib was decreasing, and severer hematological toxicities increasing with the disease progressing in patients with Ph+ CML. Imatinib improves progression-free survival significantly in most patients in accelerated phase, particularly in those with continuous CCyR or MMoR. The response duration in majority of blastic phase patients is short, and the relapse rate is high.