Background: Several clinical trials in chronic phase (CP) chronic myeloid leukemia (CML) showed that early response to tyrosine kinase inhibitor (TKI) treatment results in an improved long-term survival and progression-free survival. This study assessed whether patients achieving early treatment response (ETR; partial cytogenetic response or BCR-ABL1 mRNA ≤10% at 3 months) in daily practice also have a long-term survival benefit.
Methods: The Retrospective Evaluation of Early response in CML for long-term Treatment outcome (R-EFECT), a multicenter, retrospective chart review, documented patients with newly diagnosed CML-CP starting first-line TKI therapy in routine clinical practice. The primary aim was to assess the 5‑year overall survival rate.
Results: Of the 211 patients from 12 centers across Austria (January 2004-May 2010), 176 (median age, 56 years) were included in the analysis. All patients received first-line therapy with imatinib. Overall, 136 patients (77.3%) achieved ETR (ETR+ group), whereas 40 (22.7%) did not reach ETR (ETR- group). The ETR+ group had higher 5‑year overall survival (92.5% vs. 77.5%, P = 0.018) and progression-free survival (95.6% vs. 87.5%, P = 0.06) rates compared with the ETR- group. As expected, more patients in the ETR- group were switched to another TKI. At the last contact, 120 patients were still on imatinib and 44 had switched to another TKI (25 to nilotinib, 15 to dasatinib, and 4 to bosutinib).
Conclusion: The data are in line with randomized trials demonstrating that ETR is associated with improved survival and thus confirmed these results in patients treated in daily clinical routine.
Keywords: Chronic myeloiud leukemia; Chronic phase; Clinical routine; Retrospective evaluation; Tyrosine kinase inhibitors.