Unfavourable Outcome and Heterogeneity of Partner Chromosomes in Chronic Lymphocytic Leukemia with 14q32/IGH Translocations.

Translocations of 14q32/IgH have a low incidence in CLL. Partner chromosomes and the prognostic significance are poorly defined. Four hundred thirty cases of CLL seen at the Hospitals of Ferrara, Salamanca and Siena between 1992 and 2006 were studied. Inclusion criteria were:

• diagnosis of CD5/CD19+ CLL with k/λ restriction,

• cytogenetic/FISH data,

• immunophenotypic data,

• complete hematological and clinical data. Lymphomas in leukemic phase were excluded.

FISH was performed for 17p13/TP53, 11q22.3/ATM, 6q21, chr 12 centromere, 13q14 and 14q32/IGH. Patients with no detectable aberration or isolated 13q− were included into a favourable cytogenetic group (group 1), those with +12, 6q− or 1–2 aberrations into an intermediate risk group (group 2) and those with 17p−, 11q−, ≥ 3 aberrations into an unfavourable group (group 3). Cases with 14q32/IGH translocation as primary chromosome change represented a specific category (group 4) and were studied with FISH probes for the detection of partners (BCL1, BCL2, BCL3, BCL6, c-MYC, BCL11A, PAX5, CCND3, CDK6). One hundred eighty-six cases were allocated into group 1; 158 into group 2; 64 into group 3, and 22 into group 4. Additional aberrations were found in a minority of cells in 8 patients in group 4. Being the aim of the study to assess whether the 14q32/IGH translocation represented an unfavourable parameter as compared with cases in the favourable or intermediate cytogenetic risk groups, cases within group 3 were excluded from the analysis and the data presented here will refer to 366 patients belonging to groups 1,2 and 4. Translocation partners of 14q32/IGH were identified in 9/22 cases: 2p13/BCL11A, (n 1); 6p21/CCND3 (n 1); 7q21/CDK6 (n 1); 18q21/BCL2 (n 6). Thirteen cases did not show involvement of the loci studied. Cases with 14q32/IGH translocations were characterized by typical morphology and classical immunophenotype (score 4–5 in 92% of the cases). Unmutated IGVH genes were found in 11/18 cases tested (61%); ZAP-70 was positive in 3/5 cases tested. Median age was 63.5 years (range 18–97), male:female ratio 240/126; 345 patients were in Rai stage 0-II, 21 were in stage 3–4; CD38 was positive in 137/366 cases. There was no difference between groups 1,2 and 4 for age, stage, male:female ratio, hematological parameters at diagnosis, IGVH mutations and ZAP70. CD38 was more positive in group 4 than in group 1 (p=0.028). There was no difference in survival and treatment free interval (TFI) when comparing cases in group 4 with and without additional aberrations. Cases in group 4 had a shorter TFI and a shorter survival when compared with group 1 (p=0.02) and group 2 (p=0.02). The difference maintained its statistical significance at multivariate analysis for TFI (p=0.02) along with stage (p<0.0001) and CD38 positivity (p<0.0001) and for survival (p=0.02) along with sex (p=0.006) and stage (p=0.0001). In conclusion, the 14q32/IGH translocation in CLL shows heterogeneity of partner chromosomes and it represents a cytogenetic marker predicting for an evolutive form of CLL.