Outcome of Imatinib Treatment in Yemeni Patients With Chronic Myeloid Leukemia and the Influence of Nonadherence to Treatment and Duration of Previous Hydroxyurea Therapy.

In a developing country like Yemen, data are limited regarding the outcome of imatinib treatment of chronic myeloid leukemia and the effect of nonadherence to imatinib treatment and previous duration of hydroxyurea treatment. A longitudinal cohort study, which included 164 Yemeni patients, was performed. Data regarding the disease characteristics, adherence to treatment (the medication possession ratio) and outcome were analyzed. After a median follow-up of 60 months and a median duration of imatinib treatment of 46 months, 79 (48.2%) patients were adherent to treatment. In adherent patients, the overall survival and progression-free survival (PFS) were 78 (98.7%) and 73 patients (92.4%), respectively and major molecular response (MMR) rates at 12 months and at 46 months were 32 (41.0%) and 45 patients (57.0%), respectively, compared with 67 (78.8%), 51 (60%), 5 (6.9%), and 2 patients (2.4%), respectively, in nonadherent patients (P < .001 for all parameters). Nonadherence to imatinib treatment and duration of hydroxyurea treatment of more than 12 months before starting imatinib were found to adversely affect PFS in univariate (hazard ratio [HR], 7.5 and 9.7, respectively and P < .001 for both) and multivariate (HR, 5.6 and 9.3; P = .001 and P < .001, respectively) analysis. High risk Sokal score was found to adversely affect PFS in univariate analysis (HR of high to low risk, 2.8; P < .022) but not in multivariate analysis. Yemeni patients who were adherent to imatinib therapy achieved response rates similar to that of international standards. Nonadherence to imatinib treatment and previous duration of hydroxyurea treatment for more than 12 months, as a proxy of long interval between diagnosis and starting imatinib treatment, reduced the optimal response to imatinib therapy.