Rationale and design of a prospective, multicentre, stop tyrosine kinase inhibitor trial of paediatric patients with chronic myeloid Leukaemia with sustained complete molecular response (STKI-14)

Chronic myeloid leukaemia (CML) is a relatively rare disease in children, accounting for 2-3% of all paediatric leukaemia cases. Generally, children with CML can avoid hematopoietic stem cell transplantation and achieve molecular responses with tyrosine kinase inhibitors (TKI). However, CML stem cells are thought to survive in many patients, even after TKI treatment. Many aspects of the toxic effects of prolonged exposure to TKIs during childhood remain unclear, particularly those regarding growth impairment. This lack of clarity underscores the importance of the present clinical trial, which aims to clarify the feasibility of treatment-free remission (TFR) in children following TKI treatment. We aim to examine the long-term outcomes and complications of TKIs before and after cessation to better understand the unknown complications that could arise in adulthood. This trial targets patients who were diagnosed with CML at an age younger than 20 years, were in the chronic or accelerated phase at initial diagnosis and remained in complete molecular remission for at least 2 years after TKI administration. We will examine the utility of TKI cessation and assess the treatment results of patients who resumed TKI therapy after losing a major molecular response. We will also investigate factors related to the feasibility of a TFR after TKI cessation.