title: BCR-ABL1 doubling times more reliably assess the dynamics of CML relapse compared with the BCR-ABL1 fold rise: implications for monitoring and management.
abstract: Rising BCR-ABL1 transcripts indicate potential loss of imatinib response in CML. We determined whether the BCR-ABL1 doubling time could distinguish nonadherence from resistance as the cause of lost response. Distinct groups were examined: (1) acquired clinical resistance because of blast crisis and/or BCR-ABL1 mutations; and (2) documented imatinib discontinuation/interruption. Short doubling times occurred with blast crisis (median, 9.0 days; range, 6.1-17.6 days; n = 12 patients), relapse after imatinib discontinuation in complete molecular response (median, 9.0 days; range, 6.9-26.5 days; n = 17), and imatinib interruption during an entire measurement interval (median, 9.4 days; range, 4.2-17.6 days; n = 12; P = .72). Whereas these doubling times were consistently short and indicated rapid leukemic expansion, fold rises were highly variable: 71-, 9.5-, and 10.5-fold, respectively. The fold rise depended on the measurement interval, whereas the doubling time was independent of the interval. Longer doubling times occurred for patients with mutations who maintained chronic phase (CP: median, 48 days; range, 17.3-143 days; n = 29; P < .0001). Predicted short and long doubling times were validated on an independent cohort monitored elsewhere. The doubling time revealed major differences in kinetics according to clinical context. Long doubling times observed with mutations in CP allow time for intervention. A short doubling time for a patient in CP should raise the suspicion of nonadherence.
authors.affiliation: Department of Genetics and Molecular Pathology, Centre for Cancer Biology, SA Pathology, Adelaide, SA 5000, Australia. susan.branford@health.sa.gov.au
authors.forename: Susan
authors.initials: S
authors.lastname: Branford
authors.forename: David T
authors.initials: DT
authors.lastname: Yeung
authors.forename: Jodi A
authors.initials: JA
authors.lastname: Prime
authors.forename: Soo-Young
authors.initials: SY
authors.lastname: Choi
authors.forename: Ju-hee
authors.initials: JH
authors.lastname: Bang
authors.forename: Jin Eok
authors.initials: JE
authors.lastname: Park
authors.forename: Dong-Wook
authors.initials: DW
authors.lastname: Kim
authors.forename: David M
authors.initials: DM
authors.lastname: Ross
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Hughes
mesh_terms: D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D001549:Benzamides; D014408:Biomarkers, Tumor; D001752:Blast Crisis / Q000201:enzymology; D019468:Disease Management; D018450:Disease Progression; D004334:Drug Administration Schedule; D016903:Drug Monitoring; D019008:Drug Resistance, Neoplasm; D016044:Fusion Proteins, bcr-abl / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology*; D015466:Leukemia, Myeloid, Chronic-Phase / Q000188:drug therapy / Q000201:enzymology / Q000473:pathology; D055118:Medication Adherence; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011743:Pyrimidines / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012334:RNA, Neoplasm / Q000096:biosynthesis / Q000235:genetics; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D012008:Recurrence; D012189:Retrospective Studies; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D000068877:Imatinib Mesylate; D016044:Fusion Proteins, bcr-abl