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.
Authors: Nguyen-Khac Florence , Leporrier Nathalie , Radford-Weiss Isabelle , Lefebvre Christine , Bastard Christian , Hagemeijer Anne , Tigaud Isabelle , Debraekeleer Marc , Lessard Michel , Davi Frederic , Lesty Claude , Michel Leporrier , Merle-Beral Helene , Raynaud Sophie D. , Sutton Laurent 
Published: April 2020

Abstract
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&lt;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.