Tyrosine kinase inhibitor discontinuation in patients with chronic myeloid leukemia: a single-institution experience

BackgroundPatients with CML treated with TKI can have a life expectancy comparable to that of the general population. Due to the extended duration of TKI administration, treatment discontinuation has been increasingly sought.MethodsMedical records of 100 patients with CML who were in MR4.5 and discontinued their TKI outside clinical trials were reviewed.ResultsAfter a median follow-up of 30months (range, 5-112months) after discontinuation, 35% and 17% lost MR4.5 and major molecular response (MMR), respectively. Only six patients lost MMR 12months or more after discontinuation. Loss of MR4.5 was observed in 29% and 7% of patients with sustained MR4.5 duration of more than 2 and 6years before discontinuation, respectively. By univariate analysis, there was a higher risk of loss of MR4.5 for patients who were treated for less than 87months, received second or subsequent line TKI, never received interferon, or those with sustained MR4.5 for less than 6years. By multivariate analysis, sustained MR4.5 for 6years or more was the only significant predictor for durable response. Overall, 30% of patients who discontinued while in MR4.5 were retreated with 93% regaining MR4.5 at a median of 5months.ConclusionThese results demonstrate that under proper conditions, treatment discontinuation is feasible outside of clinical trial setting. MR4.5 duration of 6years or more before discontinuation is associated with very low risk of loss of MR4.5.