Gender, Age and TP53 Aberrations in Context of Complex Karyotypes in Chronic Lymphocytic Leukemia Patients in the Era of Chemo +/- Immunotherapy

Chronic lymphocytic leukemia (CLL) is the most common adult leukemia characterized by a heterogeneous course of the disease. Determination of prognosis of patients (pts) is based on clinical and laboratory parameters, where cytogenetic examination plays a significant role. According to recent studies the complex karyotype (CK) shows to have adverse prognostic value and occurrence of CK is reported in 15-20% of untreated pts. Multiple diverse chromosomal translocations, deletions, duplications, numerical changes or dicentric chromosomes arise within complex karyotypes.

Our aims were to determine the CK frequency in our cohort of untreated CLL pts, to verify its prognostic significance and to validate whether TP53 disruptions or ATM deletions involved in CK affect survival of pts. Moreover we aimed to investigate types of chromosomal aberrations implied within the CK in detail and to identify their possible adverse prognostic impact.

A total of 644 untreated CLL pts (diagnosed according to iwCLL criteria) were examined at Department of Hemato-Oncology, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, Olomouc, Czech Republic (in years 1996-2017). Peripheral blood or bone marrow samples were examined by classical and molecular cytogenetic and molecular genetic methods (G-banding, FISH, mFISH, arrayCGH, PCR, sequencing, NGS - Illumina, MiSeq) using standard protocols.

CK was detected in 79 pts (12.3%, 57 men and 22 women), median of age at diagnosis was 64 years (34-87 years). The most frequently detected recurrent changes in pts with CK were deletions of 13q14 (68%), 11q22 (43%), 17p13 (33%) and duplication of 8q24 (27%). Chromosomes mostly included in CK were chromosomes 13, 11, 17, 2, 8 and 6, respectively. Sixty pts (76%) had unmutated IGHV status and 6 pts (8%) mutated IGHV3-21 . TP53 gene mutations were detected in 25 pts out of 71 examined pts

with CK (35%), 19 of pts (27%) had both deletion and TP53 mutation.

Statistical analysis has shown a lower overall survival (OS) rate of CK pts compared to pts without CK (77 months vs. 115 months, p<0.0001). We also observed influence of gender and age on the OS of CK pts. More adverse outcome has been seen in women with CK compared to women without CK (37 months vs. 154 months, p<0.0001; men with CK vs. men without CK 84 months vs. 106 months, p = 0.0049) and also in pts with CK with age over 60 years (pts with CK over 60 vs. pts with CK under 60: 68 months vs. 123 months, p=0.0075). The effect of presence of translocations, numerical changes and dicentric chromosomes as part of the CK on patient´s survival has not been demonstrated (p=0.5; p=0.35; p=0.62). The deletions of TP53 and ATM genes have not occurred simultaneously in our CK cohort and the survival of these pts has not been worse. Nevertheless we could see a trend to worse survival in pts with CK and TP53 deletion/mutation (p=0.076). However, pts without CK with the occurrence of ATM or TP5 3 deletions have had a comparable negative prognostic impact just as the pts with CK (p=0.37/p=0.78).

In accordance with other authors we proved that pts with CK occurring before treatment had significantly shorter survival compared to pts without CK. Importantly, the occurrence of CK in CLL has the worst impact on OS of pts older than 60 years. Moreover OS has shortened the most significantly in women with CK compared to women without CK in our single center experience. To our best knowledge these findings was not reported by other authors so far. To explain this phenomenon it would be necessary to extend studied cohort of pts with CK. Using of standard cytogenetic methods completed with modern molecular genetic analyses remains essential for risk stratification of CLL pts. Finally, not only pts with TP53 aberrations, but also pts with CK could be possible candidates for new treatment approaches.

This work was supported by grants: VES16-32339A, IGA_LF_2017_007.