Patients with chronic-phase chronic myeloid leukemia (CP-CML) who respond to first-line tyrosine kinase inhibitor (TKI) treatment may have better responses than those who switch to a second-line treatment within 3 years, according to research published in the European Journal of Haematology.

Researchers examined data from the SIMPLICITY trial ( Identifier: NCT01244750), an ongoing observational trial in 7 countries for patients with CP-CML receiving first-line TKI treatment. The authors used data from 370 patients in the European cohort who were followed for at least 3 years to understand how switching TKI treatment may affect outcomes.

Patients who stayed on first-line TKI therapy had better treatment-related responses compared with patients who switched treatment within the 3-year observation period. Of the patients who switched TKI therapy within 3 years, 87.5% had a complete cytogenetic response compared with 91.7% of patients who did not switch therapy; 82.4% of patients who switched therapy within 3 years experienced a major molecular response compared with 91.7% of patients who did not switch.

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Patients were more likely to switch therapy within the first year than in later years. In the study, 58 patients switched in the first year, 26 in the second year, and 10 in the third year. Intolerance was the most common reason for switching, followed by primary resistance and acquired resistance. Resistance increased in the second and third years, but intolerance remained the most common reason for discontinuing or switching treatment.

Despite differences in response, the 3-year survival was high for both groups (96.4% for non-switchers vs 95.3% for switchers). The authors suggested that this could mean response is an indicator of long-term survival, but more follow up will be needed to confirm.

The authors suggested that clinical response monitoring should be ongoing for CP-CML patients and begin early in the treatment process. In the cohort, 87% of patients received monitoring with either a cytogenetic response or molecular response test within the first 6 months. The authors argued that infrequent monitoring may be a confounding factor in clinical practice.

Patients who remain on first-line TKI treatment have better clinical responses than those who switch treatment. Clinical response monitoring and careful first-line treatment selection can help maximize tolerability and address intolerance early for successful CP-CML management.

Disclosures: Some authors have declared affiliations with or received grant support from the pharmaceutical industry. Please refer to the original study for a full list of disclosures.


Gambacorti-Passerini C, Chen C, Davis C, et al. Treatment patterns and clinical outcomes of tyrosine-kinase inhibitors in chronic-phase CML in clinical practice: 3-year European SIMPLICITY data. Eur J Haematol. Published online September 28, 2020. doi:10.1111/ejh.13524