Treatment-free remission in chronic myeloid leukaemia patients with accelerated phase or tyrosine kinase inhibitor therapy failure.

We studied 60 chronic myeloid leukaemia (CML) patients with a prior history of accelerated phase (AP) including de novo AP (n = 19) and transformation to AP (n = 4), or tyrosine kinase inhibitor (TKI) therapy failure in the chronic phase (CP, n = 37), who discontinued TKI therapy. Median interval from diagnosis with AP or TKI therapy failure to achieving a deep molecular response (DMR) was 19 months (interquartile range [IQR], 9-30 months). Median TKI treatment and DMR duration were 108 months (IQR, 72-137 months) and 59 months (IQR, 39-87 months) respectively. At a median follow-up of 21 months (IQR, 11-36 months) after TKI discontinuation, 19 (31%) patients lost the major molecular response (MMR). The 3-year probability of a sustained MMR was 59% (95% confidence interval [CI], [45%, 78%]). In the multivariable analyses, age at discontinuation <32 years (hazard ratio [HR] = 4.1 [1.3, 12.7], p = 0.014) and BCR::ABL1 >0.1% at 12 months on TKI therapy (reference, ≤0.1%; HR = 3.9 [1.4, 11.5], p = 0.011) were significantly associated with a higher probability of MMR loss after TKI discontinuation. CML patients with a history of AP or TKI therapy failure may achieve successful treatment-free remission after an adequate TKI therapy duration and a sustained DMR.