Prognostic relevance of monosomy at the 13q14 locus detected by fluorescence in situ hybridization in B-cell chronic lymphocytic leukemia

Deletion of the chromosome band 13q14, which contains the putative deleted in B-cell malignancy (DBM) gene, and trisomy 12 have been demonstrated by f luorescence in situ hybridization (FISH) techniques in malignant B-cells fr om patients with B cell chronic lymphocytic leukemia (B-CLL). However, the prognostic relevance of 13q14 abnormalities as detected by FISH is unknown. We prospectively studied malignant blood cells from 54 consecutive, untrea ted B-CLL patients using FISH probes to the RBI locus and DBM (markers D13S 25 and D13S319) for band 13q14, as well as probes to chromosome 12. The cel ls from all cases were CD5+ CD20+, expressed clonally restricted surface im munoglobulin light chain, and had typical features for B-CLL on careful blo od smear morphologic evaluation. Patients were followed for a mean of 3.9 y ears and treatment-free survival (TFS) was used in the prognostic factor an alysis. Twenty-four (44%) patients were observed to have monosomy of the RB I locus and 26 (48%) monosomy of D13S25 and D13S319. The 26 patients who ha d a deletion at at least one of these loci had a 48.4 month (mol median TFS vs 31.1 mo for those without evidence of deletion at any 13q14 locus (p = 0.07). The seven patients found to have trisomy 12 had a median TFS of 6.9 mo vs 39.3 mo for those diploid for chromosome 12 (p < 0.01). When these se ven patients with trisomy 12 were excluded from the analysis, patients who had a deletion at 13q14 tended to have a longer median TFS (50.1 vs 36.2 mo s), but this was not statistically significant Ip = 0.2). This study confir ms the prevalence of 13q14 deletions in B-CLL and suggests that patients wi th this abnormality have a better TFS than those with trisomy 12. (C) Elsev ier Science Inc., 1999. All rights reserved.