Frequency and prognosis of Clonal Chromosomal Abnormalities Following Stem Cell Transplantation (SCT) in Acute Myeloid Leukemia (AML)

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

Patients and methods. From February 2000 to March 2008, 74 patients were studied. Karyotypes were analysed by G-banded chromosomes obtained from 24 hours bone marrow cultures, and were described according to ISCN 2005.

Results. Clonal abnormalities were observed in 17/74 patients (23%). Median follow-up was 11 months (range 5–47). Initial diagnosis: AML2 (6 cases), AML5a (3), AML6 (3), AML with inv(16)(p13;q22) (1), AML with multilineage dysplasia (1), AML5b (1), AML1 (1) and AML0 (1). Treatment before SCT: idarubicin, cytarabine and etoposide (16), FLAG-ida (1). All patients presented a normal karyotype at the time of SCT. SCT type: autologous (12 patients), allogeneic (3), allogeneic of reduced intensity (2). Conditioning regimen: TBI and cyclophosphamide (14 cases), busulfan and cyclophosphamide (1), fludarabine and busulfan (2). The median time between SCT and the appearance of clonal abnormalities was 8 months (range 3–36). At the time of clonal abnormality detection, 16 patients were in cytological and/or clinical relapse and 1 in complete remission. In 4 cases the initial clone reappeared, 1 showed the initial abnormalities with an acquired abnormality and 12 presented de novo clonal abnormalities. The median survival from the appearance of clonal abnormalities was 2 months (range 1–40). At the time of the analysis all patients had died.

Conclusions.

1. The appearance of clonal abnormalities following SCT in patients with AML is frequent.

2. Time between SCT and the appearance of clonal abnormalities is short.

3. The majority of patients presented de novo clonal abnormalities with cytological and/or clinical relapse and poor prognosis.