Analysis of Karyotype Aberrations in Children and Adolescents with Post-Transplantation Relapses of Acute Leukemia

Aim. To analyze the karyotype aberrations at the relapse after allogeneic HSCT (alloHSCT) in children and adolescents with acute leukemias, in order to evaluate their relation with disease-free survival and overall survival (OS) rates after the relapse and to identify prognostic groups of patients based on clinical and cytogenetic characteristic of a tumor. Methods. Cytogenetic investigations were performed in 30 children and 15 adolescents (26 males and 19 females aged from 1.2 to 21 years; median age 10 years) with a post-transplant relapse (PTR) of acute myeloid leukemia (n = 29) and acute lymphoblastic leukemia (n = 16). The analysis of aberrating chromosomal abnormalities was performed by comparison of the karyotypes in relapse with those before the alloHSCT. Results. Karyotype aberrations in PTR were observed in 29 (64 %) patients. 2 and more abnormal cytogenetic clones were observed in 10 (34 %) patients with PTR. Additional chromosomal aberrations acquired in PTR were related primarily to chromosomes 1, 11 and 19. OS after the relapse was higher in patients with alloHSCT performed during the remission and with one abnormal cytogenetic clone in PTR. Based on this, we formed three prognostic groups: the first group consisted of 8 (18 %) patients with 2 adverse factors and median 40-day OS after relapse; the second group included 20 (44 %) patients with 1 adverse factor and median OS after PTR equal to 152 days, and the 4-year survival was 16 %; the third group included 17 (38 %) patients without the above negative factors and median OS after relapse equal to 549 days, and the 4-year survival was 31 %. The multivariate analysis showed that the number of abnormal cytogenetic clones in leukemic population is an independent predictor of OS after PTR. Conclusion. The presence of leukemic population of ³ 2 abnormal cytogenetic clones is the most important prognostic factor affecting the OS in PTR patients. Since the clonal evolution of the karyotype may be associated with the use of cytotoxic drugs in the therapy of acute leukemia in children and adolescents with indications for alloHSCT, the latter should be done as soon as possible and non-myeloablative conditioning regimen should be preferred.