Clinical Significance of Clonal Cytogenetic Heterogeneity (CCH) at Diagnosis in Adult Patients with Acute Lymphoblastic Leukemia (ALL)

• Published in: Blood 2018-11, Vol.132 (Supplement 1), p.2820-2820
• Main Authors: Shimizu, Hiroaki, Hatsumi, Nahoko, Takada, Satoru, Ishizaki, Takuma, Yokohama, Akihiko, Saitoh, Takayuki, Sakura, Toru, Handa, Hiroshi
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2018-99-118462

Background:Although cytogenetic abnormalities at diagnosis are recognized as one of the most potent prognostic factors in acute leukemia patients, CCH acquisition at diagnosis, which are considered as a result of clonal evolution of leukemia cells, is not taken into account in prognostic classifications. Recent studies reported that CCH acquisition was observed in 24 - 32% of adult AML patients with abnormal karyotype, was more likely to occur in patients with older age and complex karyotype, and showed adverse prognostic impact. However, the clinical significance of CCH acquisition has not been investigated in adult ALL patients to date. Patients and methods: Of the 238 adult ALL patients diagnosed between 1990 and 2016, 120 patients with abnormal karyotype at diagnosis, who underwent intensive chemotherapy, were included in this study. CCH was defined as presence of two or more cytogenetically abnormal clones. A defined ancestral clonal evolution included either mother-daughter and/or branched patterns. In the mother-daughter pattern, a daughter clone showed all cytogenetic abnormalities of a mother clone plus additional abnormality(s), which define a distinct subclone. In a branch pattern, all subclones possessed common cytogenetic abnormalities suggesting presence of a common ancestry, but each subclone acquires unique additional abnormality(s), which define them as distinctive subclones. Both patterns of cytogenetic clonal evolution were sometimes seen in a patient. Composite karyotypes were applied to patients where a common ancestry could not be clearly determined because of too complicated cytogenetic findings. Fisher's exact test was used to compare binary variables. The logistic regression model was used for multivariate analysis of predisposing factors. Overall survival (OS) was estimated with the Kaplan-Meier method and compared using the log-rank test. The Cox proportional hazard model was used for multivariate analysis of prognostic factors. Values of p < 0.05 were considered to indicate statistical significance. Results:Of the 120 patients included in this study, 64 patients were male, and 56 were female. The median age was 50 years (range, 16-79 years). Karyotypes at diagnosis were Philadelphia chromosome (Ph) in 56 patients, complex in 15, and t(8;14) in seven. According to the definition described above, 47 patients (39%) showed CCH at diagnosis, and two (4%) among them were categorized as composite karyotype. Of the 45 patients harboring