Comparison of Cytogenetic Clonal Evolution Patterns following Allogeneic Hematopoietic Transplantation versus Conventional Treatment in Patients at Relapse of AML

Relapse of acute myelogenous leukemia has been associated with clonal cytogenetic evolution but no study focused specifically on relapse after allogeneic hematopoietic stem cell transplantation (HSCT) We compared karyotypes in 160 patients at both diagnosis and relapse either after allo-HSCT (n = 26) or standard chemotherapy (n = 134) using chromosome banding analysis combined with fluorescein in situ hybridization There were 71 females and 89 males (19 7-80 6 years) At diagnosis aberrant karyotypes were more frequent in the HSCT than in the chemotherapy cohort (16 of 26 61 5% versus 63 of 134 47 0%) This was most obvious in patients with unfavorable cytogenetics (8 of 26 30 8% versus 19 of 134 14 2% P = 032) Differences in the karyotypes between diagnosis and relapse were more frequent in the allo-cohort (14 of 26 538% versus 49 of 134 366%) than in the conventional cohort (n s) mainly because of newly emerging cytogenetic alterations Appearance of new clonal alterations was more frequent in the allo cohort (6 of 12 50 0% with clonal evolution versus 5 of 41 12 2% P = 005) The mean number of cytogenetic alterations per patient was increasing Irom 20 at diagnosis to 40 at relapse in the allo-cohort in the con ventionally treated patients from 09 to I 3 (both P < 001) Thus higher frequencies of clonal evolution and increasing cytogenetic complexity were observed in the stem cell recipients probably related to the more unfavorable cytogenetic profiles already depicted at diagnosis