Switching from imatinib to dasatinib in the case of sub-optimal response in chronic myeloid leukemia

This study aimed to investigate the outcome of early switching from imatinib to dasatinib of patients with chronic-phase chronic myeloid leukemia with weak responses to imatinib treatment. 

The study concluded that this switch may offer clinical benefit in certain patients.

Imatinib (Gleevec) is a targeted therapy used to treat chronic myeloid leukemia (CML). ?Imatinib is often used as a first-line treatment for CML. Dasatinib (Sprycel) is a targeted therapy that can also be used to treat CML. 

Molecular response (MR) measures the amount of BCR-ABL gene in blood. The BCR-ABL gene is found in cancer cells. An early MR is associated with improved chances of deep MR (DMR) and better survival in patients with chronic phase CML (CP-CML).  33% of patients treated with imatinib as first-line treated do not achieve these outcomes. 

It was unknown if switching CP-CML patients from imatinib to dasatinib due to a weak response was safe and effective.  

This study involved 260 adult patients with CP-CML. 174 patients received dasatinib after not achieving optimal response with first-line imatinib. The other 86 patients continued on imatinib. They were followed up for 2 years or more. 

The rate of major MR (MMR) at 12 months was 29% for the dasatinib group compared to 13% for the imatinib group. The average time until MMR was 14 months in the dasatinib group compared to 20 months in the imatinib group.

After 2 years of follow up, 52% of patients who were in the imatinib group crossed over to the dasatinib treatment. Taking treatment crossover into account, the 2-year MMR rate was 64% for dasatinib and 41% for imatinib.  

This study concluded that early monitoring of CP-CML patients treated with first-line imatinib should be carried out, and switching to dasatinib in cases of weak response may offer better outcomes. 

Further follow-up is needed to assess the long-term clinical benefit of early switching. This study was funded by Bristol Myers Squibb, the manufacturer of dasatinib.