BCR-ABL1 mutation development during first-line treatment with dasatinib or imatinib for chronic myeloid leukemia in...

Area of Science:

• Hematology
• Oncology
• Molecular Biology

Background:

• BCR-ABL1 mutations are a primary resistance mechanism to imatinib in chronic myeloid leukemia.
• Understanding mutation development with newer tyrosine kinase inhibitors like dasatinib and nilotinib is crucial due to their increased use and higher response rates.

Purpose of the Study:

• To characterize BCR-ABL1 mutation development in patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP) treated with dasatinib versus imatinib.
• To compare the spectrum and types of mutations that arise during first-line therapy with these agents.

Main Methods:

• Retrospective analysis of patients from the DASISION trial (n=519) with a minimum 3-year follow-up.
• Mutation screening was performed on patients who discontinued treatment or experienced on-treatment events indicating resistance.
• Analysis included patients treated with either dasatinib (n=259) or imatinib (n=260).

Main Results:

• A small number of patients developed mutations (17 on dasatinib, 18 on imatinib).
• Dasatinib treatment was associated with a narrower spectrum of BCR-ABL1 mutations (4 sites) compared to imatinib (12 sites).
• Fewer phosphate-binding loop and multiple mutations were observed with dasatinib; however, T315I mutations were more frequent (11 vs 0 patients).

Conclusions:

• First-line dasatinib therapy in CML-CP is associated with a distinct pattern of BCR-ABL1 mutation development compared to imatinib.
• The observed differences in mutation spectrum, including the higher incidence of T315I with dasatinib, warrant further investigation.
• These findings contribute to understanding resistance mechanisms in CML and inform treatment strategies.