TKI Use and Treatment-Free Remission in Chronic Myeloid Leukemia: Evidence from a Regional Cohort Study in the Canary Islands

<b>Background/Objectives</b>: The advent of tyrosine kinase inhibitors (TKIs) revolutionized the management of chronic myeloid leukemia (CML), achieving survival rates near those of the general population. Despite this success, prolonged therapy presents challenges, including physical, emotional, and financial burdens. Treatment-free remission (TFR), defined as sustained deep molecular response (DMR) after discontinuing TKIs, has emerged as a viable clinical goal. This study evaluates real-world data from the Canary Islands Registry of CML (RCLMC) to explore outcomes, predictors, and the feasibility of TFR. <b>Methods</b>: This retrospective observational study included 393 patients diagnosed with CML-CP between 2007 and 2023. Molecular response was monitored according to international guidelines. Survival probabilities were estimated using the Kaplan-Meier method. Logistic regression analysis was performed to identify predictors of molecular relapses after TKI discontinuation. <b>Results</b>: Of the 383 patients who received TKI treatment, 58.3% achieved molecular response grade 2 (MR2) (BCR-ABL1 ≤ 1%), 95.05% achieved MR2, and 50.5% reached MR4 within the first year. Of the 107 patients attempting TFR, 73.2% maintained remission at 36 months. Relapses occurred in 24 patients, all regaining molecular response upon reintroduction of TKIs. No cases of disease progression were observed. <b>Conclusions</b>: Our findings support the feasibility and safety of TFR in a real-world clinical setting for well-selected patients, with outcomes consistent with international studies. The study underscores the importance of molecular monitoring and patient-specific strategies to optimize outcomes.