Effect of Time to Major Molecular Response on Survival: Testing in Community Practice

Imatinib has revolutionized the treatment of chronic myeloid leukemia (CML), allowing prolonged remissions in patients with chronic-phase disease. However, a substantial number of patients develop resistance and require alternative treatment. Consistent monitoring of bcr-abl transcript levels during treatment is important in the management of CML. The prognostic value of achieving a major molecular response at 12 months is increasingly recognized. Additionally, rising bcr-abl transcript levels provide an early indication of a potential loss of response to treatment. Quantitative reverse-transcriptase polymerase chain reaction is the most sensitive method for detecting changes in the overall disease burden of CML. The recommendations of the National Comprehensive Cancer Network suggest measuring transcript levels every 3 months in patients who respond to treatment with imatinib when a complete cytogenetic response is achieved. Dasatinib and nilotinib are alternative tyrosine kinase inhibitor therapies approved for the treatment of patients with CML who fail initial imatinib therapy. This review discusses the role of molecular monitoring in the management of CML, the methodology used, and molecular responses reported for the available treatments.