Abstract Background Most patients with chronic myeloid leukemia (CML) treated with tyrosine kinase inhibitors (TKIs) will relapse if treatment is withdrawn, but various trials have recently demonstrated that a significant proportion of patients who achieved a stable and deep molecular response (DMR) can stop therapy without relapsing. However, most information on treatment cessation was obtained from clinical trials with strict recruiting criteria. Methods We evaluated the outcome of 25 patients with CML that discontinued TKI therapy in our institute in real-world clinical practice. Results Of the 25 patients, 76% discontinued therapy in sustained deep molecular response (SDMR) and 24% were in unsustained DMR (UDMR). Discontinuation of therapy due to adverse effects was observed in 5 and 50% of the patients in the SDMR and UDMR groups, respectively. After TKI discontinuation, patients were followed for a median of 24 months. At the time of this analysis, 56% patients had a molecular relapse after a median of 4 months. SDMR and longer treatment duration were associated with lower probability of molecular relapse: 25% in SDMR patients with TKI treatment > 96 months and 85% in UDMR patients with TKI treatment ≤96 months. All relapsed patients promptly resumed TKI therapy and regained at least major molecular response (MMR). Conclusions Our results suggest that TKI discontinuation is safe outside clinical trials and particularly effective in CML patients who are in SDMR with longer TKI treatment duration.
