Discontinuation of Tyrosine Kinase Inhibitor Therapy and Treatment Free Remission (TFR) in Chronic Myeloid Leukemia: Successful Achievement of TFR in More Than Two-Third of Patients in a Real-World Practice

Background: Discontinuation of TKI therapy and treatment-free remission (TFR) have become new goals for chronic- phase chronic myeloid leukemia (CP-CML). The aim of this study was to estimate the TFR post discontinuation of TKI therapy at 3 tertiary-care centers. Patients and Methods: CP-CML patients aged >= 16 years who had an attempt to discontinue TKI therapy till June 2022, were eligible. The collected data included patients' demographics, prognostic score, type and duration of TKI therapy, response dates, relapse dates, response to re-initiation of TKI therapy, and risk factors for relapse. Results: Fifty-five patients (35, 63.6% females) with a median age of 40 (range 16-74) years at diagnosis discontinued therapy. Forty-eight (87.3%) patients received imatinib as first line therapy. Twenty-nine (52.7%) patients were receiving imatinib at the time of TKI-discontinuation. Median time from diagnosis to TKI discontinuation was 86 months (IQR 60;132) and median duration of TKI therapy after achieving DMR was 66 months (IQR 47;114). After a median follow up of 34 (IQR 12;68) months, 15 (27.3%) patients relapsed. Median time to relapse was 5 months (range 2-38). Most of the relapses occurred during the first 6 months except 3 (20%) patients. All the relapsed patients achieved MMR after a median of 3 (range 2-6) months after restarting TKI therapy. None of the patients progressed to advanced-phase. Conclusion: Our experience confirms that discontinuation of TKI therapy in CP-CML patients is feasible and safe in routine clinical practice, and can achieve TFR in more than two-third of carefully selected patients.