Treatment Cessation in Chronic Myeloid Leukemia: Evidence and Uncertainties

Testing to discontinue imatinib already started some years after the advent of this new CML therapy. Since that time, despite many trials and studies in this field, there are still significant gaps, and many fundamental questions remain unanswered. Probably the most intriguing is the persistence of minimal residual disease, which does not lead to disease recurrence in all patients. Nevertheless, today's understanding enables TKI to be safely discontinued in eligible patients outside clinical trials. Notwithstanding, TKI cessation still has to be considered and indicated with caution, taking into account several important viewpoints, like: (i) why stop the therapy in a particular patient, and are all the eligible patients willing to cease the treatment? (ii) Will all the TKI-related side effects relieve upon stopping? (iii) are there any side effects after discontinuing treatment? This review covers extensively all aspects of treatment cessation, like history, theoretical background, eligible patients, monitoring after treatment discontinuation, trigger for retreatment, therapy restart, predictive factors for successful therapy cessation, immunological aspects, potential complications of TKI withdrawal, late molecular relapses, blast crisis development, kinetics of preexisting TKI-related side effects and laboratory values, and quality of life upon treatment cessation. The art of treatment cessation is to select the best candidate based on many diverse facts and information, and follow the patient in the most rational way with smartly anticipating the potential risks and side effects.