1. ¹Department of Immunology and Transfusion Medicine, University Hospital of Northern Norway, University of Tromsø, Tromsø, Norway
2. ²Biochemistry Department, Institute of Medical Biology, University of Tromsø, Tromsø, Norway
3. ³Department of Pharmacology, Institute of Pharmacy, University of Tromsø, Tromsø, Norway
4. ⁴Section of Hematology, Medical Department, Rikshospitalet University Hospital, Oslo, Norway
5. ⁵Section of Hematology, Medical Department, St Olavs University Hospital, Trondheim, Norway

Correspondence: Dr FXE Gruber, Department of Immunology and Transfusion Medicine, University Hospital of Northern Norway, Breivika, Tromsø 9038, Norway. Fax: +47 776 26304; E-mail: franz.gruber@unn.no

Received 17 June 2005; Accepted 14 September 2005; Published online 13 October 2005.

Abstract

Resistance to imatinib during the treatment of chronic myeloid leukaemia (CML) is frequently associated with point mutations in the ABL gene encoding the ATP binding region likely to cause disease relapse. Early diagnosis and monitoring of these mutations may be important in order to prevent rapid expansion of resistant clones. We describe a quantitative mutation-specific PCR assay based on the readily available Taqman platform. Selectivity for the mutated target is conferred by mutation-specific primers destabilised by additional mismatches. The assay can be carried out in parallel to standard BCR-ABL quantification and is therefore more quickly compared to standard sequencing procedures. The sensitivity of the assay reaches 0.1%. It also allows for quantitative assessment of mutated clones. By analysing sequential samples of resistant subjects, we show how mutated clones were selected, maintained or deselected depending on the individual treatment setting. The high sensitivity and practical merits of this method makes it a good candidate for prospective molecular surveillance of patients at high risk for imatinib resistance.