ELN 2013 response status criteria: relevance for de novo imatinib chronic phase chronic myeloid leukemia patients?

The response definitions proposed by the European Leukemia Net (ELN) have been recently modified. We evaluated the new criteria for de novo imatinib (400 mg/d) chronic phase chronic myeloid leukemia (CP-CML) patients. Response status according to the 2009 and 2013 criteria were determined in 180 unselected patients. Outcome of the subgroups of patients were then compared. The 180 patients were classified as optimal responders (OR2009; n = 113, 62.7%), suboptimal responders (SOR2009; n = 47, 26.1%) and failures (FAIL2009; n = 20, 11.1%) according to the 2009 ELN criteria and optimal responders (OR2013; n = 77, 42.7%), warnings (WAR2013; n = 59, 32.7%), and failures (FAIL2013; n = 44, 24.4%) according to the 2013 ELN criteria. No difference in terms of outcome was observed between OR2009 patients who became WAR2013 when compared with OR2013 patients. When compared with FAIL2009 patients, SOR2009 patients who became WAR2013 had better EFS, FFS, PFS, and OS. No difference was observed in PFS or OS in SOR2009 patients who became FAIL2013. The 2013 ELN response status criteria have improved patients classification in terms of response status. However, in our patient population this improvement is related to a better definition of failure rather than that of optimal response for CP-CML patients treated with IM frontline therapy.

Achieving deeper molecular response is associated with a better clinical outcome in chronic myeloid leukemia patients on imatinib front-line therapy.

Sustained imatinib treatment in chronic myeloid leukemia patients can result in complete molecular response allowing discontinuation without relapse. We set out to evaluate the frequency of complete molecular response in imatinib de novo chronic phase chronic myeloid leukemia patients, to identify base-line and under-treatment predictive factors of complete molecular response in patients achieving complete cytogenetic response, and to assess if complete molecular response is associated with a better outcome. A random selection of patients on front-line imatinib therapy (n=266) were considered for inclusion. Complete molecular response was confirmed and defined as MR 4.5 with undetectable BCR-ABL transcript levels. Median follow up was 4.43 years (range 0.79-10.8 years). Sixty-five patients (24%) achieved complete molecular response within a median time of 32.7 months. Absence of spleen enlargement at diagnosis, achieving complete cytogenetic response before 12 months of therapy, and major molecular response during the year following complete cytogenetic response was predictive of achieving further complete molecular response. Patients who achieved complete molecular response had better event-free and failure-free survivals than those with complete cytogenetic response irrespective of major molecular response status (95.2% vs. 64.7% vs. 27.7%, P=0.00124; 98.4% vs. 82.3% vs. 56%, P=0.0335), respectively. Overall survival was identical in the 3 groups. In addition to complete cytogenetic response and major molecular response, further deeper molecular response is associated with better event-free and failure-free survivals, and complete molecular response confers the best outcome.