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In 2004, we reported the short-term results of a multicentric, phase 2 study of imatinib 400 mg daily and pegylated interferon-alpha in the treatment of 76 early chronic phase Philadelphia-positive chronic myeloid leukemia patients. In this report, we update the results with an observation time of five years. After two years of treatment, all but 10 patients (13%) had discontinued pegylated interferon-alpha. The complete cytogenetic response rate at five years was 87%, and 94% of complete cytogenetic responders maintained the complete cytogenetic response after five years. All but one complete cytogenetic response also achieved a major molecular response. These data confirm the excellent response to imatinib front-line and the stability of the complete cytogenetic response. Any possible additional benefit of the combination with interferon-alpha remains uncertain, due to low patient compliance.

Additional chromosomal abnormalities (ACAs) in Philadelphia-positive cells have been reported in ∼ 5% of patients with newly diagnosed chronic myeloid leukemia (CML) in chronic phase (CP). Few studies addressing the prognostic significance of baseline ACAs in patients treated with imatinib have been published previously. The European LeukemiaNet recommendations suggest that the presence of ACAs at diagnosis is a “warning” for patients in early CP, but there is not much information about their outcome after therapy with tyrosine kinase inhibitors. To investigate the role of ACAs in early CP CML patients treated with imatinib mesylate, we performed an analysis in a large series of 559 patients enrolled in 3 prospective trials of the Gruppo Italiano Malattie Ematologiche dell'Adulto Working Party on CML: 378 patients were evaluable and ACAs occurred in 21 patients (5.6%). The overall cytogenetic and molecular response rates were significantly lower and the time to response was significantly longer in patients with ACAs. The long-term outcome of patients with ACAs was inferior, but the differences were not significant. The prognostic significance of each specific cytogenetic abnormality was not assessable. Therefore, we confirm that ACAs constitute an adverse prognostic factor in CML patients treated with imatinib as frontline therapy. This study was registered with clinicaltrials.gov as NCT00514488 and NCT00510926.

Purpose Imatinib mesylate (IM) has rapidly become the front-line treatment of Philadelphia-positive (Ph-pos) chronic myeloid leukemia, but the number of patients who were treated and are being treated with IM second-line is still substantial. Patients and Methods We have monitored and analyzed the cytogenetic and molecular response to IM 400 mg/d in a cohort of 277 late chronic phase (LCP) patients who were resistant or intolerant to interferon-α and were observed for 48 to 79 months (median, 72 months). Results One hundred fifty-three patients (55%) achieved a complete cytogenetic response (CCgR). Seventy-seven percent of them were still in CCgR after 5 years. The rate of response loss did not increase over time. The 6-year progression-free survival and overall survival of these 153 complete cytogenetic responders were 90% and 91%, respectively. Molecular response was less than major in 21%, major in 78%, and complete in one patient only. Conclusion These data confirm that, in LCP the CCgR rate to IM is 50% to 60%, and show that CCgR is stable and is associated with a prolonged survival, even if leukemia continues to be molecularly detectable.

CML patients who obtain a complete cytogenetic response (CCgR) may harbor different degrees of molecular disease, which are associated with different progression-free survival. We have compared the pattern and the magnitude of the molecular response (MolR) of 54 early chronic phase (ECP) and of 115 late CP patients who achieved a stable CCgR with IM 400 mg/daily. ECP patients obtained earlier, higher and more sustained MMolR.