Cytogenetic and molecular monitoring of residual disease in chronic myeloid leukaemia

For patients with chronic myeloid leukaemia, methods for monitoring response to treatment have changed considerably in recent years. In the 1980s, the principal approach was repeated examination of bone marrow metaphases for the presence of the Ph chromosome in patients treated by interferon-alpha (IFN-alpha) or allogeneic stem cell transplantation. The use of fluorescence in situ hybridisation (FISH) techniques to detect the BCR-ABL fusion gene in Ph-positive leukaemia cells increased the sensitivity of cytogenetic studies to some degree. In the last 10 years, the reverse-transcriptase polymerase chain reaction (RT-PCR) has proved extremely valuable for assessing and monitoring minimal residual disease in patients who achieve Ph negativity after treatment with IFN-alpha or with the new Abl tyrosine kinase inhibitor imatinib mesylate or after allogeneic stem cell transplantation (SCT). Results are consistent with the notion that the majority of long-term survivors after allogeneic SCT are probably 'cured'; for other patients monitored serially in complete cytogenetic remission, rising numbers of BCR-ABL transcripts detected by RT-PCR can indicate the need for further therap