How complete is “complete” molecular response in imatinib-treated chronic myeloid leukemia?
Authors: David M. Ross a; Timothy P. Hughes Elsewhere in this issue of the journal Verma and colleagues 1 report a case in which a complete molecular response (CMR) induced by imatinib treatment was sustained for at least 2 years after cessation of imatinib. Imatinib mesylate is a highly effective treatment for chronic phase chronic myeloid leukemia. With increasing duration of imatinib therapy there is a progressive reduction in BCR-ABL levels measured by real-time reverse transcriptase Q-PCR. Some patients will have undetectable BCR-ABL using sensitive reverse transcriptase PCR methods. Sustained undetectable BCR-ABL using RT-PCR with a sensitivity of at least 4.5-log below the pre-treatment BCR-ABL level is often referred to as CMR. The probability of CMR on imatinib therapy is very low in the first 2-3 years of treatment, but thereafter there is ongoing recruitment of patients to CMR so that around 40-50% of first-line imatinib-treated patients will have undetectable BCR-ABL mRNA a
