The only current curative treatment for chronic myeloid leukemia (CML) is allogeneic stem cell transplantation (SCT). However, relapses occur in 10-30% of patients transplanted in chronic phase and even more frequently in patients transplanted in later phases of CML.
As relapses can appear after long-term molecular remissions detected by nested RT-PCR for BCR-ABL transcript, the question arises of what isthe origin of cells whose activation results in a relapse. A rational explanation seems to be the persistence of cells with an unexpressed BCR-ABL gene.
The question of existence of such transcriptionally silent BCR-ABL cells was addressed by several authors with contradictory conclusions.