Early detection of relapse after bone marrow transplantation in patients with chronic myelogenous leukaemia.

In patients with chronic myelogenous leukaemia (CML) treated by allogeneic bone marrow transplantation (BMT), detection of residual leukaemic cells carrying the characteristic bcr/abl rearrangement by highly sensitive techniques, such as qualitative polymerase chain reaction (PCR), is of limited value in predicting disease progression. We have therefore adapted the PCR for quantitative assessment of bcr/abl rearranged cells and applied this technique to the monitoring of residual disease in 28 CML patients during up to 106 months of follow-up after BMT. In 5 patients, quantitative PCR revealed increasing amounts of the pathological bcr/abl message, indicating the presence of a proliferating neoplastic clone, and all 5 had a subsequent relapse of disease. By contrast, the remaining 23 patients have been in maintenance-free complete remission for up to 106 months post-BMT. The monitoring by quantitative PCR of residual leukaemic cells during the post-transplant course of CML patients may allow early detection of relapse and provide a rationale for the timely initiation of treatment.