title: Kinetics of BCR-ABL fusion transcript levels in chronic myeloid leukemia patients treated with STI571 measured by quantitative real-time polymerase chain reaction.
abstract: The activated tyrosine kinase, which arises as a result of the balanced t(9,22) translocation in chronic myeloid leukemia (CML), is thought to be essential for the development of the leukemic phenotype. Recently, designer drugs have been introduced which specifically inhibit such specific kinases. Among these, STI571 (Glivec) has entered clinical trials and shown promising activities in chronic phase (CP), accelerated phase (AP) and blast crisis (BC) as evidenced by significant hematological and cytogenetic responses in CML patients. To evaluate the effect of STI571 at the molecular level we have employed quantitative real-time PCR (RQ-PCR) to measure the amount of BCR-ABL fusion transcript in a series of 19 patients treated with STI571, either in CP(11) or in (AP)(8) of the disease for 3--9 months (median 6 months). Employing this method, which is able to detect at least one BCR-ABL+ cell in 500,000, in serial blood and bone marrow specimens we found decreases in transcript levels in 10/11 CP patients, but only in 1/8 of the AP patients. When present such decreases were gradual and became evident only after 3 months of STI571 treatment, and their kinetics in blood closely mirrored those seen in parallel marrow samples. Moreover, decreases were between 10- and 100-fold in 11/13 patients, with only two patients reaching residual disease levels below 10(-2) (a 900-fold decrease). Thus, no patient reached PCR negativity. We conclude that the RQ-PCR method is a highly suitable tool for following the effect of STI571 in CML and that further validation of the method, performed in a prospective manner, will contribute significantly to the elucidation of the proper role of STI571 in CML.
authors.affiliation: Department of Hematology, Arhus University Hospital, Arhus, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Stentoft
authors.forename: N
authors.initials: N
authors.lastname: Pallisgaard
authors.forename: E
authors.initials: E
authors.lastname: Kjeldsen
authors.forename: M S
authors.initials: MS
authors.lastname: Holm
authors.forename: J L
authors.initials: JL
authors.lastname: Nielsen
authors.forename: P
authors.initials: P
authors.lastname: Hokland
mesh_terms: D000328:Adult; D000368:Aged; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D001549:Benzamides; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors / Q000627:therapeutic use*; D005260:Female; D016044:Fusion Proteins, bcr-abl / Q000097:blood / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D000068877:Imatinib Mesylate; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000097:blood / Q000188:drug therapy* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011743:Pyrimidines / Q000627:therapeutic use*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D014158:Transcription, Genetic
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D014408:Biomarkers, Tumor; D004791:Enzyme Inhibitors; D010879:Piperazines; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D011505:Protein-Tyrosine Kinases; D016044:Fusion Proteins, bcr-abl