Clonal evolution in chronic lymphocytic leukemia studied by interphase fluorescence in-situ hybridization.

The results of repeated interphase fluorescence in-situ hybridization (I-FISH, FISH) examination of 97 CLL patients and correlation of these findings with IgVH hypermutation status, ZAP-70 and CD38 expression are presented. The appearance of new, FISH-detectable, genomic aberrations during disease course, described as clonal evolution (CE), was observed in 26% of patients. The most frequent newly acquired cytogenetic abnormality was 13q deletion in 64% (16/25). In contrast to earlier studies, there was no correlation found between CE and either one of single negative prognostic factors (unmutated IgVH; CD38 positivity; ZAP-70 positivity). However, the combination of all three negative factors correlated with CE highly significantly (p=0.005) and moreover, also with a shift from lower to higher FISH risk category (p=0.010). As the prognostic data were known in all patients, this study represents the complete insight on the association of CE and other risk parameters in CLL.