In patients with chronic myeloid leukemia in chronic phase (CML-CP), prolonged treatment with imatinib helps to achieve a deeper molecular response over 5 years, a study published in the journal Clinical Lymphoma, Myeloma & Leukemia has shown.1

Complete cytogenetic response in patients with CML-CP treated with first-line imatinib therapy is associated with improved clinical outcome; however, the effect of obtaining a molecular response and the depth of the response on outcomes remains unclear. Therefore, researchers sought to determine the frequency of complete molecular response during long-term follow-up and assess how complete molecular response impacts outcomes and survival.

For the study, investigators analyzed data from 131 patients with CML-CP receiving imatinib. Complete molecular response was defined as undetectable BCR-ABL transcripts by real-time quantitative polymerase chain reaction with a sensitivity level of 10–4 or greater on 2 consecutive analyses at least 3 months apart. 

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During a median follow-up of 65 months, results showed that 67% of patients achieved a complete molecular response. Researchers found that patients who achieved a complete cytogenetic response at 12 months and a major molecular response at 18 months were more likely to achieve a complete molecular response, suggesting that achieving deeper molecular response helps patients to maintain the cytogenetic and molecular response.

The study further demonstrated that fewer events were reported in patients who achieved a complete molecular response vs those who achieved a major molecular response (26.1% vs 50.0%), meaning a deeper molecular response may reduce the risk for transformation to accelerated and/or blast phase.

There was no significant difference in overall survival between those who had a complete molecular response and those who had a major molecular response; however, a complete molecular response was associated with a borderline significant improvement in progression-free survival.


1. Atagunduz IK, Toptas T, Deniz R, et al. Effects of deeper molecular responses on outcomes in chronic myeloid leukemia patients in chronic phase treated with imatinib mesylate. Clin Lymphoma Myeloma Leuk. 2016 Sep 16. doi: 10.1016/j.clml.2016.09.006. [Epub ahead of print]