Dose Modifications and Interruptions of Imatinib and Cytarabine and Required Evaluations

High-dose imatinib versus high-dose imatinib in combination with intermediate-dose cytarabine in patients with first chronic phase myeloid leukemia: a randomized phase III trial of the Dutch-Belgian HOVON study group

Noortje Thielen,1 Bronno van der Holt,2 Gregor E.G. Verhoef,3 Rianne A.H.M. Ammerlaan,2 Pieter Sonneveld,4 Jeroen J.W.M. Janssen,1 Wendy Deenik,5 J.H. Frederik Falkenburg,6 Marie José Kersten,7 Harm A.M. Sinnige,8 Martin Schipperus,9 Anton Schattenberg,10 Rien van Marwijk Kooy,11 Willem M. Smit,12 Isabel W.T. Chu,4 Peter J.M. Valk,4 Gert J.Ossenkoppele,1 and Jan J. Cornelissen4

1 Department of Hematology, VU University Medical Center, Amsterdam, the Netherlands; 2 HOVON Data Center, Erasmus University Medical Center-Daniel den Hoed, Rotterdam, the Netherlands; 3 Department of Hematology, University Hospital Gasthuisberg, Leuven, Belgium; 4 Department of Hematology, Erasmus University Medical Center, Rotterdam, the Netherlands; 5 Department of Internal Medicine, Tergooiziekenhuizen, Hilversum, the Netherlands; 6 Department of Hematology, Leiden University Medical Center, Leiden, the Netherlands; 7 Department of Hematology, Academic Medical Center, Amsterdam, the Netherlands; 8 Department of Hematology, Jeroen Bosch Hospital, ’s Hertogenbosch, the Netherlands; 9 Department of Hematology, Haga Hospital, The Hague, the Netherlands; 10 Department of Hematology, Radboud University Nijmegen Medical Center, Nijmegen, the Netherlands; 11 Department of Internal Medicine, Isala Klinieken, Zwolle, the Netherlands and 12 Department of Internal Medicine, Medisch Spectrum Twente, Enschede, the Netherlands

Correspondence: Noortje Thielen, Department of Hematology, VU University Medical Center, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; tel: 0031-20-4442604; fax: 0031-20-4442601, e-mail:

BCR-ABL PCR

Molecular responses were locally assessed in the molecular laboratories of the various HOVON centers. A laboratory-specific conversion factor to the international scale (IS) was acquired via EUTOS for CML [1].The quality of the BCR-ABL real-time quantitative PCR quantification was monitored by the Dutch Network for Molecular Diagnostics of Hematologic malignancies (MODHEM) by means of annual quality control rounds. Recommended protocols for determination of the type of t(9;22) chromosomal breakpoint detection, RQ-PCR and criteria for reliable BCR-ABL quantification are available on the MODHEM website ( RQ-PCR analyses were only carried out by laboratories qualified according to the quality standards as defined by MODHEM. As described in the MODHEM guidelines positive controls (K562, BV173 and TOM1 cell lines) were included in all RQ-PCR assays. For routine analyses local serial dilutions of the positive controls were included to quantify and determine the sensitivity of the assay. Because not all laboratories had the IS conversion factor, two calibrators were used by those participating laboratories, which were included in each BCR-ABL RQ-PCR assay performed within the HOVON 78 study. An undiluted K562 sample (calibrated to a BCR-ABL mRNA level of a CML patient at diagnosis) was used to calculate the relative BCR-ABL levels. The BCR-ABL levels were expressed relative to the undiluted K562 calibrator to exclude inter-laboratory variation. A second calibrator, i.e., a 1/10000 (10-4) dilution of K562 in HL60, was included to determine the sensitivity of the BCR-ABL RQ-PCR assay. All RQ-PCR amplifications reached a sensitivity of at least 10−4 (K562/HL60) in duplicate and an efficiency of at least 93%.

References

1. Hughes T, Deininger M, Hochhaus A, Branford S, Radich J, Kaeda J et al (2006) MonitoringCML patients responding to treatment with tyrosine kinase inhibitors: review and recommendations for harmonizing current methodology for detecting BCR-ABL transcripts and kinase domain mutations and for expressing results. Blood 108:28-37