Frequency and Prognosis of Clonal Chromosomal Abnormalities Following Stem Cell Transplantation (SCT) in Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS)

To study the frequency, type and prognostic significance of clonal chromosomal abnormalities following SCT in patients with AML and MDS.

One hundred thirty patients were studied between 2000 and 2010. Karyotypes were analysed by G-banded chromosomes obtained from 24 hours bone marrow cultures, and were described according to ISCN 2009.

Clonal abnormalities were observed in 36/130 patients (28%) with a median follow-up was 11 months (range 3–131). Initial diagnosis (OMS 2008): AML with maduration (8 patients), acute erythroid leukaemia (4), acute monocytic leukaemia (3), AML with multilineage dysplasia (3), AML with myelodysplasia-related changes (3), AML with inv(16)(p13q22) (2), acute monoblastic leukaemia (2), AML with minimal differentation (2), AML without maduration (1), acute myelomonocytic leukaemia (1), refractory anaemia with excess blasts (4), chronic myelomonocytic leukaemia (2) and refractory cytopenia with multilineage dysplasia (1). Treatment before SCT: idarubicin, cytarabine, etoposide and mitoxantrone (25), idarubicin, cytarabine and etoposide (6), idarubicin, cytarabine, etoposide and gemtuzumab (2), FLAG-ida (2) and azacitidine (1). SCT type: autologous (23 patients), allogeneic of reduced intensity (7), allogenic (4), umbilical cord blood (1) and syngeneic transplant (1). Conditioning regimen: TBI and cyclophosphamide (24 cases), fludarabine and busulfan (7), busulfan and cyclophosphamide (4) and thymoglobulin, thiotepa, fludarabine and busulfan (1). The median time between SCT and the appearance of clonal abnormalities was 6.5 months (range 2–51). At the time of clonal abnormality detection, 32 patients were in cytological and/or clinical relapse and 4 in cytological remission. In 15 cases the initial clone reappeared, 2 showed the initial abnormalities with an acquired abnormality and 19 presented de novo clonal abnormalities (53%). The most frequent clonal chromosomal abnormalities observed were: complex karyotype (22%), estructural abnormalities with afection of chromosomes 1, 4, 6, 7, 10, 11, 12, 16 and 17 (22%), +21 (5%) and +11 (3%). The median survival from the appearance of clonal abnormalities was 2.5 months (range 1–100). There were no differences when we compared the survival of patients with de novo clonal abnormalities with that of patients with initial abnormalities (including those with acquired abnormality). Furtheremore there were no differences when we compared the median survival of relapsed patients with normal Karyotype with that of patients with clonal chromosomal abnormalities following SCT (2.5 months [range 1–25] and 2.5 months [range 1–100] respectively). At the time of the analysis only 1 patients are alive and in complete remission (100 months).

1. The appearance of clonal abnormalities following SCT in patients with AML and MDS is frequent and the majority of cases are detected at the time of relapse. Half of cases presented de novo clonal abnormalities and the majority were not related with prior irradiation exposition, alkylating agents neither topoisomerase II inhibitors. The prognosis of patients with acquired clonal abnormalities after SCT is poor.

No relevant conflicts of interest to declare.