Imatinib Mesylate Dose Adjustment Based on Body Surface Area for CML Chronic Phase Patients Intolerant to Standard...

Chronic myelogenous leukemia (CML) chronic phase (CP) patients cannot tolerate a standard dose (400 mg/day) of imatinib mesylate (IM), sometimes needing a reduced dose. This study aimed to find convenient clinical indexes, rather than plasma trough levels of IM, to define the appropriate IM dosage.

Seventy CML CP patients who experienced an IM dose reduction, or a temporary cessation, were enrolled from 2002 to 2010. The IM treatment was resumed and maintained at either ≥400 mg in 25 patients (35.7%; group ≥400 mg) or at ≤300 mg in 45 patients (64.3%; group ≤300 mg). The various clinical characteristics of these patients were evaluated. The plasma trough level of IM was monitored in 20 patients from group ≤300 mg.

Via multivariate analysis, the IM dosage divided by the body surface area (BSA) was an important index, presupposing a complete cytogenetic response at 12 months (CCyR12). Patients with IM/BSA >206.7 mg/m2 showed a higher probability of CCyR12 than others. The IM/BSA (221.7 mg/m2) in group ≤300 mg was higher than in group ≥400 mg (207.6 mg/m2). The sustained response and survival rate of group ≤300 mg was comparable to that of group ≥400 mg. The plasma trough level of IM was significantly correlated with the IM/BSA.

Our study suggests that IM dose adjustments, based on IM/BSA, could improve the clinical outcomes in CML CP patients.