[Secondary treatment-free remission in chronic myeloid leukemia in the chronic phase: a case series and literature review].

Data and guidelines for a second attempt at treatment-free remission (TFR) in patients with chronic myeloid leukemia in the chronic phase (CML-CP) are limited. We retrospectively analyzed the clinical data of six patients with CML-CP who attempted a second discontinuation of tyrosine kinase inhibitors (TKIs) for TFR at Peking University People's Hospital from October 2006 to October 2024. Before the first TKI discontinuation, all six patients had received imatinib treatment for a median of 82.5 months (range, 40-87 months) and maintained a sustained deep molecular response, specifically MR(4.5), for a median of 34.5 months (range, 24-62 months). They lost major molecular response (MMR) at a median of 3 months (range, 2-4 months) after discontinuing imatinib treatment. All six patients resumed TKI treatment within 4 weeks following failure of the first TFR (TFR1). After a median of 4.5 months (range, 3-7 months) on TKI, they achieved MR(4.5) again and voluntarily attempted a second TKI discontinuation at 93, 84, 76, 76, 33, and 44 months, respectively, after resuming therapy. Four out of six patients maintained TFR, with sustained TFR durations of 42, 23, 21, and 58 months, respectively. All four patients who had resumed TKI treatment for >6 years and maintained MR(4.5) for >5 years achieved a sustained second TFR of ≥21 months; among these, three had received second-generation TKI for >1 year during the resumption of TKI treatment. The other two patients lost MMR at 4 and 3 months, respectively, after the second TKI discontinuation but regained MR(4.5) at 2 and 3 months, respectively, after resuming TKI treatment again.