Imatinib mesylate therapy in chronic myeloid leukemia patients in stable complete cytogenic response after interferon-alpha results in a very high complete molecular response rate

Abstract To determine the impact on minimal residual disease by switching to imatinib chronic phase chronic myeloid leukaemia (CP-CML) patients responsive to interferon-alpha (IFNα), in stable complete cytogenetic response (CCR) but with persistent PCR positivity. Twenty-six Philadelphia positive (Ph+) CML patients in stable CCR after IFNα but persistently positive at PCR analysis during this treatment, were given imatinib mesylate at standard dose. At enrolment into the study, median IFN treatment and CCR duration were 88 months (range 15–202) and 73 months (range 10–148), respectively. Imatinib treatment resulted in a progressive and consistent decline of the residual disease as measured by quantitative PCR (RQ-PCR) in all but one of the 26 patients; at the end of follow-up, after a median of 32 months (range 21–49) of treatment, a major molecular response (BCR/ABL levels p These results indicate that patients induced into CCR by IFN treatment represent a subset with very favourable prognosis, which can significantly improve molecular response with imatinib and further support investigative treatment schedules combining these two drugs.