Background and importance Currently, one of the most burning issues regarding the specific treatment of chronic myeloid leukaemia (CML) with interleukin-2 inducible T cell kinases (ITK) is whether in some patients who meet specific requirements treatment interruption could be attempted and molecular relapse free survival maintained without restarting treatment. This would mean a reduction in the side effects related to the medication and a progressive increase in the quality of life for patients.

Aim and objectives To analyse molecular relapse free survival after suspension of imatinib, nilotinib or dasatinib, which achieved and maintained a major molecular response (MMR) ≥4.5 log for at least 36 months.

Material and methods This was a prospective observational study of patients with chronic phase Ph+CML (CP-CML). Inclusion criteria were minimum ITK treatment time of 5 years, no resistance to a previous ITK, no accelerated phase diagnosis or blast crisis and those who had achieved and maintained MMR ≥ 4.5 log for at least 36 months prior to treatment interruption. These patients were candidates for discontinuation of ITK. Molecular monitoring of bcr-abl oncogene levels was performed using the real time reverse polymerase chain technique with the GeneXpert automated system with a sensitivity of 5 log.

Results Thirty patients with CP-CML were discontinued: 13 discontinued imatinib treatment, 3 discontinued dasatinib treatment and 14 discontinued nilotinib treatment. The preliminary rates of molecular relapse free survival and treatment free remission were consistent with those obtained in clinical trials, and no progression to advanced stages of the disease was reported. With a median follow-up of 15 months, 78% remained without specific treatment with ITK and had not lost MMR. Relapse occurred before 6 months of discontinued treatment with a median of 4 months. Four patients lost MMR, recovering all MMR 4.5 and 5.0 at 3 months after restarting ITK treatment.

Conclusion and relevance The results contribute towards reassurance of the safety of TKI treatment discontinuation in real life clinical practice, under close molecular monitoring. Resolution of TKI related toxicity might translate to clinical benefit for patients with CP-CML with a potential improvement in quality of life.

References and/or acknowledgements No conflict of interest.