Current event-free survival after sequential tyrosine kinase inhibitor therapy for chronic myeloid leukemia

Background: Imatinib is an effective tyrosine kinase inhibitor (TKI) for patients with chronic myeloid leukemia (CML) in chronic phase (CP). Although some patients may fail on therapy with imatinib, effective salvage therapy is available with second-generation TKIs. Current measurement of efficacy for each therapy is judged by its individual impact on overall survival and event-free survival (EFS). Methods: In total, 586 patients with CML in CP who received imatinib were included in this analysis in 2 cohorts: imatinib as front-line therapy (n = 281) or after failure on interferon-α (IFN-α) (n = 305). By accounting for successful salvage treatment (ie, regain of complete cytogenetic response), the current EFS (CEFS) rate was calculated to obtain a more accurate impression of the outcome of patients with CML who received treatment with sequential TKIs. Results: For patients who received imatinib after failing on IFN-α, the 7-year EFS rate was 61%, whereas the CEFS rate was 69%. The 7-year EFS rate for patients who received imatinib as initial therapy was 81% compared with a 7-year CEFS rate of 88%. Conclusions: CEFS provided a more accurate representation of the outcome of patients with CML in CP. These patients may frequently be treated successfully with subsequent TKIs after experiencing failure on the first TKI.