Monitoring of remission status by fluorescence in situ hybridisation in chronic myeloid leukaemia patients treated with interferon-alpha

Interferon-alpha (IFN-alpha) can be considered as treatment of choice for p atients with chronic myeloid leukaemia (CML) in chronic phase. With this tr eatment major cytogenetic responses can be achieved in 30% to 50% of patien ts. Regular monitoring of cytogenetic response is essential for the therape utic management of these patients As conventional cytogenetics is not alway s successful, especially under IFN-alpha treatment, molecular cytogenetic m ethods have been established for the examination of interphase nuclei for t he presence of the BCR-ABL fusion gene, the molecular counterpart of the Ph iladelphia chromosome. To demonstrate the value of these new methods we hav e analysed interphase nuclei from sequentially cultured bone marrow cells f rom 14 CML patients who were treated with IFN-alpha and whose bone marrow w as investigated regularly during therapy. Dual-colour FISH with a breakpoin t spanning BCR-YAC and a flanking cosmid from the ABL region was applied. W hen compared with conventional cytogenetics the results achieved by FISH we re favourable. The most evident advantage of FISH analysis is that in case of failure of conventional cytogenetics a reliable determination of the rem ission status can be done. Together with other recent studies our results i llustrate the advantages and limitations of the interphase FISH method for monitoring CML patients.