Seven-year response to imatinib as initial treatment versus re-treatment in Chinese patients with chronic myelogenous leukemia in the chronic phase.

The purpose of our study is to compare the 7-year response to imatinib monotherapy as an initial treatment and re-treatment in Chinese patients with chronic myelogenous leukemia-chronic phase (CML-CP) patients in a single center in Beijing. A retrospective study of 171 CML-CP patients receiving imatinib monotherapy was done with 73 in the initial treatment group (disease course ≤ 6 months) and 98 in the re-treatment group (disease course > 6 months). Cumulative rates of complete cytogenetic response (CCyR) at 6, 12, and 36 months after imatinib treatment in the initial and re-treatment groups were 75%, 89%, and 96%, and 48%, 77% and 84% (p = 0.0002), respectively. The median time to CCyR in the initial and re-treatment groups was 6 months (95% CI, 3.3-8.3) and 9 months (95% CI, 6.4-11.6), respectively (p = 0.0002). Cumulative rates of major molecular responses at 9, 12, and 18 months after imatinib treatment in the initial and re-treatment groups were 31%, 48%, and 60%, and 15%, 25% and 37% (p = 0.017), respectively. The median time to the major molecular response in the initial and re-treatment groups was 15 months (95% CI, 12.3-17.7) and 36 months (95% CI, 25.9-46.0), respectively (p = 0.017). Progression-free survival at 84 months in the initial and re-treatment groups was 97% and 85%, respectively (p = 0.09). Event-free survival at 84 months in the initial and re-treatment groups was 92% and 70%, respectively (p = 0.049). Only two of the 171 patients discontinued imatinib therapy for grade 3/4 adverse events. Our study revealed that CML-CP patients would benefit from early treatment with imatinib.