Does tyrosine kinase inhibitors dose reduction influence the outcomes of patients with in chronic myeloid leukemia?

This study aimed to investigate the effect of tyrosine kinase inhibitor (TKI) dose reduction in patients with chronic myeloid leukemia (CML) after achieving a major molecular response (MMR).  

This study concluded that the TKI dose reduction was safe and effective for the majority of these patients.  

Tyrosine kinase inhibitor (TKI) is a type of targeted therapy and works by blocking the growth of cancer cells. Targeted therapies have allowed a near-normal life expectancy for patients with chronic myeloid leukemia (CML). However, other medical conditions may increase the risk of side effects of this treatment. TKI dose reduction often occurs in patients, usually because of intolerance and the occurrence of side effects. 

A major molecular response (MMR) is when there is a very low level of the BCR-ABL gene in the blood. The BCR-ABL gene is found on CML cancer cells and is responsible for the growth and spread of cancer. Reaching and maintaining MMR is the goal of TKI therapy. It was unknown if TKI dose reduction has an effect on MMR in patients with CLL.  

This study involved 245 patients with CLL. All patients received a lower dose (LD) than standard doses of TKIs after achieving major molecular response (MMR) because of intolerable side effects. Patients were followed up for an average of 27.3 months. 

At follow-up, 91.9% of patients were still in MMR despite a dose reduction. 13 patients lost MMR at an average of 13.9 months after the dose reduction. 

In patients who received imatinib (Gleevec), 92.8% were alive and without loss of MMR after 2 years. In those treated with dasatinib (Sprycel), 94% did not lose MMR after 2 years. In the nilotinib (Tasigna) group, 91.6% did not lose MMR after 2 years. In the bosutinib (Bosulif) group, 96% were still in MMR after 2 years.

76 patients stopped TKI. The two-year treatment-free remission (TFR) rate in these patients was 74.1%.  

This study concluded that LD TKI is suitable for the majority of patients in MMR. The authors suggested that LD TKI does not prevent the achievement of TFR in this patient population. 

This study was based on medical records. Information might have been missing. This might influence the results.