Patients with chronic myeloid leukemia who maintain a complete molecular response after stopping imatinib treatment have evidence of persistent leukemia by DNA PCR

Standardized definitions of molecular response in chronic myeloid leukemia

“…17 Moreover, there are reports of disease relapse following achievement of CMR on TKI-based therapy. [18][19][20] Currently, the only treatment modality available to CML patients that is considered potentially curative is allogeneic stem cell transplantation, which may induce remission via elimination of CML stem cells through a graft vs leukemia effect. 21 Still, the morbidity and mortality rate following allogeneic stem cell transplantation remains prohibitively high, precluding allogeneic stem cell transplantation as a first-line or even second-line treatment option for most CML patients.…”

“…One possibility is the measurement of BCR-ABL fusion junctions from genomic DNA, an approach that is technically demanding and labor intensive because the genomic breakpoints need to be characterized for each patient and individual detection assays designed and validated. 20,30,31 Notwithstanding these technical hurdles, one study reported that all patients (n ¼ 10) who lost CMR after imatinib cessation had detectable levels of BCR-ABL on analysis of genomic DNA, and patients who maintained CMR displayed a stable level of BCR-ABL DNA. 20 These data may provide a rationale to use genomic DNA as a methodology to monitor residual disease, at least on a research basis.…”

“…20,30,31 Notwithstanding these technical hurdles, one study reported that all patients (n ¼ 10) who lost CMR after imatinib cessation had detectable levels of BCR-ABL on analysis of genomic DNA, and patients who maintained CMR displayed a stable level of BCR-ABL DNA. 20 These data may provide a rationale to use genomic DNA as a methodology to monitor residual disease, at least on a research basis.…”

Molecular monitoring to improve outcomes in patients with chronic myeloid leukemia in chronic phase: Importance of achieving treatment‐free remission

“…The definition of CMR as the complete absence of detectable BCR-ABL1 transcripts is limited by the sensitivity of the assay used for transcript measurement [24,25,27,28]. Thus, ELN recommends use of the term molecularly undetectable leukemia, together with the number of control gene transcripts, over the term CMR [11].…”

Technical Issues Behind Molecular Monitoring in Chronic Myeloid Leukemia

“…However, the need to retrieve the breakpoint of each patient affects the routine application of this practice. Recent studies [6] also argue that chronic myeloid leukemia patients (even those with undetectable levels of chimeric RNA) maintain evidence of the BCR-ABL1 DNA, implying its limitations as a prognostic marker. The procedure used to prove this claim consisted of a nested PCR on genomic DNA and a high number of replicates to enhance the chance of detecting the target sequence.…”