Drug monitoring of imatinib levels in patients undergoing therapy for chronic myeloid leukaemia: comparing plasma levels of responders and non-responders.

PURPOSE: Imatinib mesylate is used as first line therapy in the treatment of chronic myeloid leukaemia. This study was designed to study the correlation of plasma levels of imatinib with response to the therapy.

METHODS

A total of 40 chronic myeloid leukaemia patients in the chronic phase of the disease were recruited and placed into two groups of 20 patients: imatinib responders and imatinib non-responders, respectively. Each blood sample was taken 24 h after and immediately prior to taking a 400 mg oral dose of imatinib. Drug levels were detected by high-performance liquid chromatography.

RESULTS

The mean plasma imatinib levels in the imatinib non-responders were significantly lower than those in the imatinib responders (0.70 vs. 2.34 microM, respectively; p = 0.002).

CONCLUSIONS

Plasma levels of imatinib were correlated with response to the therapy, so routine monitoring of the therapeutic levels of the drug should be carried out specifically in treatment-resistant cases for determining dose escalation.