Relationship of serum imatinib trough level and response in CML patients: long term follow-up.

One hundred and three patients with Philadelphia chromosome or BCR-ABL positive chronic myeloid leukemia (CML) in chronic phase who were on oral imatinib were included in this study. The study aimed to assess the relationship between imatinib trough serum levels and clinical outcome (as determined by molecular response) in Jordanian CML patients who have been on imatinib therapy for at least 12 months. The mean trough imatinib serum level in the group with complete molecular response (CMR) was 2891±856 ng/ml, the group with major molecular response (MMR) was 2337±434 ng/ml, the group with complete cytogenetic response (CCyR) was 1817±563 ng/ml, and the group without CCyR was 1723±673 ng/ml. A receiver operating characteristic (ROC) curve was constructed after dividing patient sample into two groups, those with MMR or better and those without MMR, in order to estimate a threshold for imatinib level that correlates with a favorable response (the former group), and analysis yielded a value of 2158 ng/ml.