An analysis has confirmed that 2013 European LeukaemiaNet (ELN) response categories can reliably predict patient long-term outcomes. In addition, the response categories are universally applicable across all commonly used tyrosine kinase inhibitor (TKI) modalities in patients with chronic myeloid leukemia (CML).1

Investigators assessed the relevance of 2013 European ELN response categories on patients treated with common frontline TKIs in CML in chronic phase (CML-CP).

In this analysis, there were 487 patients treated with imatinib (at various doses), dasatinib, or nilotinib. In the intention to treat analysis, the investigators found that the proportion of patients falling into optimal category was 89% at 3 months.

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The proportion falling into the warning category was 6%, and 6% fell into the failure ELN category. At 6 months, the study showed 78% were in the optimal category, 17% in the warning category, and 6% in the failure category. The numbers changed at 12 months with 75% in the optimal category, and 13% in both the warning and failure categories.

“We conducted the study because these recommendations, although sensible and logical, had not been validated fully. It is particularly difficult to assess what the intermediate category warning means,” said study investigator Jorge Cortes, MD, who is professor and deputy chairman of the Department of Leukemia at The University of Texas MD Anderson Cancer Center in Houston.

The investigators found that patients who had an optimal ELN response tended to have the best long-term outcomes. In addition, the study demonstrated that patients who received imatinib 800, dasatinib, or nilotinib had a higher probability of achieving optimal response at the various time points.

The study confirmed that patients who fall into the failure category tended to have poor outcomes whether assessed at 3, 6, or at 12 months. However, the outcomes for those falling into the warning category criteria at 6 or 12 months appeared to have better outcomes than those who fell into this category at 3 months.

Dr Cortes said the analysis showed that those patients falling into the warning category have a disease course that is similar to patients in the failure category when analyzed at the 3-month time point. However, the outcomes of these patients are more similar to those of patients with optimal response at 6 months and 12 months.

“The main finding is that the warning category is heterogeneous in many ways. First, because having a warning based on response at 3 months is not the same as having a warning at 6 months. Patients in the warning category at 3 months look more like patients with failure, whereas those in the warning category at 6 months look more like those with optimal response. But second, the heterogeneity extends beyond the time,” Dr Cortes told Cancer Therapy Advisor.

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“Even within the 3-month warning category, the event-free survival is poor, but few patients transform and the overall survival is still similar to that of patients with optimal response. In terms of survival, only patients with true failure as defined by the ELN have an inferior survival.”