Molecular monitoring of imatinib in chronic myeloid leukemia patients in complete cytogenetic remission: does achievement of a stable major molecular response at any time point identify a privileged group of patients? A multicenter experience in Argentina and Uruguay

Response to imatinib therapy in adult patients with chronic myeloid leukemia in Saudi population: a single-center study

No study has been published yet in the Arab world regarding response and outcome of imatinib in patients with chronic myeloid leukemia (CML). This study evaluated a total of 122 patients with CML treated with imatinib between 2001 and 2012. Survival, hematologic, cytogenetic and molecular responses and adverse events were assessed. The 5-year overall survival (OS), event free survival (EFS) and progression-free survival (PFS) rates were: 95.4 ± 2.3%, 81.4 ± 4.6% and 90.8 ± 3.2%, respectively. Significant differences in OS (p = 0.001), EFS (p = 0.001) and PFS (p = 0.001) were noted when patients were stratified by cytogenetic response. Survival by Sokal risk groups was not significant (p = 0.293). Complete hematologic response was achieved in 94 patients (93.1%), cytogenetic response in 84 (83.2%), major molecular response in 62 (61.4%) and complete molecular response in 34 (33.7%). This article presents the first evidence on the effectiveness of imatinib in patients with CML from Saudi Arabia and highlights similarities and differences in response patterns in published studies.

Deep molecular response in chronic myeloid leukemia: the new goal of therapy?

Chronic myeloid leukemia (CML) is caused by formation of the BCR-ABL1 fusion protein. Tyrosine kinase inhibitors (TKI) that target BCR-ABL1 are now the standard of care for patients with CML. Molecular monitoring of residual BCR-ABL1 mRNA transcripts, typically performed using real-time quantitative PCR, has improved treatment management, particularly for patients with CML in chronic phase. Major molecular response (MMR; i.e., a ≥3-log reduction in BCR-ABL1 transcript levels) is used in current treatment guidelines to assess prognosis. Recent evidence suggests that deeper molecular responses (≥4-log reductions in BCR-ABL1 transcript levels), particularly when attained early during treatment, may have even better correlation with long-term outcomes, including survival and disease progression. Furthermore, achieving deep molecular response is a requirement for entering trials evaluating treatment-free remission (TFR). In this review, we discuss the evolving definition of minimal residual disease and the various levels of molecular response under evaluation in current clinical studies. In addition, the available clinical data on achieving MMR and deeper levels of molecular response with TKI therapy, the prognostic value of deep molecular response, and factors that may predict a patient's ability to achieve and sustain a deep molecular response on TKI therapy are also discussed. Available data from TFR studies are addressed. We discuss current knowledge of the ideal conditions for attempting treatment discontinuation, factors predictive of molecular relapse, when TKI therapy should be restarted, and which therapeutic strategies (when administered in the first-line setting and beyond) are expected to best enable successful TFR.