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

Background: Patients 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. Methods: Medical records of 100 patients with CML who were in MR ^4.5 and discontinued their TKI outside clinical trials were reviewed. Results: After a median follow-up of 30 months (range, 5-112 months) after discontinuation, 35% and 17% lost MR ^4.5 and major molecular response (MMR), respectively. Only six patients lost MMR 12 months or more after discontinuation. Loss of MR ^4.5 was observed in 29% and 7% of patients with sustained MR ^4.5 duration of more than 2 and 6 years before discontinuation, respectively. By univariate analysis, there was a higher risk of loss of MR ^4.5 for patients who were treated for less than 87 months, received second or subsequent line TKI, never received interferon, or those with sustained MR ^4.5 for less than 6 years. By multivariate analysis, sustained MR ^4.5 for 6 years or more was the only significant predictor for durable response. Overall, 30% of patients who discontinued while in MR ^4.5 were retreated with 93% regaining MR ^4.5 at a median of 5 months. Conclusion: These results demonstrate that under proper conditions, treatment discontinuation is feasible outside of clinical trial setting. MR ^4.5 duration of 6 years or more before discontinuation is associated with very low risk of loss of MR ^4.5 .