Cytogenetics of 125 Untreated Patients with Binet Stages B or C B-CLL. Preliminary Results of a Multicentric Study from the French Cooperative Study Group on CLL.

Numerous cytogenetic and Fluorescence In Situ Hybridization (F) data have been previously published with the aim of defining prognosis subgroups of B-CLL patients. These studies included heterogeneous series of patients (treated or not, and at various stages of the disease). We have studied with conventional cytogenetic and F analyses an homogeneous cohort of 125 untreated Binet stages B or C B-CLL patients enrolled in a prospective trial on the basis of biological and morphological criteria, with a Matutes score 4/5. Karyotype (K) was systematically performed and F analysis carried out using four probes CEP12, 13q14, 11q22 (ATM), 17p13 (TP53) on metaphases and interphase nuclei. Out of 104 successful K, 65 (63%) showed abnormalities. Among them, 32% exhibited complex K, 25% balanced translocations and 35% unbalanced translocations. The most frequent abnormalities were 11q– (13%), +12 (13%), 13q– (10%), 6q– (8%), 17p– (5%), 14q32 rearrangement (5%), X or Y loss (4%), +19 (4%). Two translocations not previously reported involving the 14q32 locus were observed. F analyses were performed on 116 patients, 108 with the four probes, 8 with only 1–3 probes. 82 out of the 108 patients (76%) analyzed with 4 probes showed one or more abnormalities. Deletions of 13q were observed in 52%, ATM in 26%, TP53 in 10%, and trisomy 12 was present in 13%. Abnormal F patterns were observed in 51% of patients with normal K with at least one of the 4 probes, versus 92% of patients with abnormal K. Among abnormal K, F analyses detected additional cryptic deletions in 6/19 cases for ATM (31%), 29/39 for 13q14 (74%), and 4/9 for TP53 (45%). TP53 deletion was never detected among normal K, but in 15% of abnormal K. Among them, there were more TP53 deletion in complex K (24% vs 2%, p=0.005). Additional karyotypic abnormalities were found with a single F anomaly in 6/7 (86%) cases with del ATM, 12/17 (71%) with del13q, 4/6 (67%) with +12, 1/2 with del TP53. In the group of patients with normal F pattern, 81% had a normal K whereas 19% had an abnormal one (p<0.0001). A preliminary correlation with the immunoglobulin heavy chain variable regions (IgVH) mutational status was performed for 54 patients. The unmutated status (41/54, 76%) was more frequently associated with abnormal K (deletions 11q, ATM, and TP53, unbalanced translocations, and complex K), than mutated status. There were more del13q alone (25% vs 3%, p=0.01) and trisomy 12 in mutated patients when compared with unmutated ones. This preliminary study underscores the interest of performing both conventional cytogenetic (classically stimulated) and systematic F analysis in advanced stage CLL. Results are complementary and, as previously reported, display a better prognostic significance than F alone. Furthermore, the systematic use of the 6q21, 14q32 and CEP19 probes in F analyses should be recommended when the K is normal. Comparison with other relevant biological parameters (ZAP70, sCD23, CD38) is ongoing.