Effects of Reduced Dose of Imatinib to Korean Chrionic Myeloid Leukemia in Chronic Phase.

Some patients of CML in chronic phase receive reduced doses of imatinib due to some adverse effects. Recently, the efficacy of reduced dose of imatinib for the patients with small BSA was reported by our group and Japanese group, recently. This study was tried to verify the hypothesis of which BSA of CML patients might be an important factor to predict the effect of reduced dose imatinib.

Fifty-six patients having record of BSA from the Korea University Medical Center who were treated with imatinib were retrospectively analyzed.

All of the patients started the imatinib therapy with 400mg/day dose. 20 patients (35.7%) among them were reduced dose to 300mg and 4 of them were further reduced to 200mg/day. The main reasons for dose reduction were severe neutropenia or thrombocytopenia (grade 3 or 4) (89.4%). Following the dose reduction, the rate of toxicity was reduced and treatment was resumed and the dose was gradually increased until 9 patients tolerated a maintenance dose of 400mg/day and remainder had been taken the reduced dose. The cumulative CCR at 12 months was similar in both group (P = 0.89, 70.0% in reduced dose vs 72.7% in standard dose). The mean imatinib dose/BSA was significantly lower in patients receiving the reduced dose compared with those receiving the standard dose (P < 0.001)(183.4 ± 26.9 vs 230.5 ± 21.4), although the mean BSA didn't show the difference according to reduction of dose (P = 0.079)(1.62 ± 0.20 vs 1.75 ± 0.13). After median follow-up period of 37.3 months (6.0-76.1 months), 15 patients (75.0%) have sustained CCR in patients receiving reduced dose of imatinib.

From this study, we could find that the reduced dose of imatinib in CML patients might assure the relatively satisfactory response with low intolerable adverse effects. But we could not verify that BSA was the main factor to predict the effect of reduced dose of imatinib. So, further studies including though level of imatinib will be needed to clarify the effect of reduced dose of imatinib.

No relevant conflicts of interest to declare.