Detection of the blastic crisis cell clone in chronic myeloid leukaemia

Three patients with Ph1 positive chronic myeloid leukaemia (CML) were followed until the occurrence of blastic transformation by means of cytogenetic analysis of whole marrow or blood cells, of blast cell enriched fractions from marrow or blood and of colonies grown from these cell fractions in two culture systems. Karyotypic evolution was used to indicate the development of new clones from pre-existing cell lines either as transient phenomena during the chronic phase or as the ultimate indicators of a blastic crisis (BC). The clones which were to lead to a BC were detected some months before the clinical diagnosis of the BC. At a time before overt BC had become clinically manifest, the BC clone outgrew the other ones in culture and thus also in vitro showed specific proliferative advantages over the cell lines characteristic of the chronic phase of CML.