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Cytogenetic Evolution of Myeloid Neoplasms at Relapse after Allogeneic Hematopoietic Cell Transplantation
Methods: We performed a retrospective review of all patients who relapsed following an allogeneic HCT for a myeloid malignancy. Cytogenetic findings at diagnosis and at relapse were compared. Cytogenetic studies were performed according to conventional methods.
Results: Of 212 patients transplanted for a myeloid malignancy between 03/2004-01/2013, 43 relapsed (34AML, 1CML, 4MDS and 4MPN) at a median time of 113 days (range 22-820 days). Cytogenetic findings at relapse were different from diagnosis in 14/43 patients (32.5%). The mean number of cytogenetic alterations/patient increased from 1.09 at diagnosis to 1.51 at relapse. The majority (10/14) represented clonal evolution defined as acquisition of more complex abnormalities. This group includes 3 patients with normal karyotype at diagnosis and 7 patients who originally showed one, two, or complex abnormalities. All of these 10 patients developed complex abnormalities (defined as >3 abnormalities). Other than clonal evolution, new-onset chromosomal abnormalities unrelated to diagnosis were seen in three patients, two of which acquired a more favorable cytogenetic profile than at diagnosis (inverted chromosome 16 and a single abnormality in a patient with complex karyotype at diagnosis, respectively). One patient with normal karyotype AML acquired a donor-derived del(20q) abnormality.
Conclusions: Cytogenetic change is common at relapse of myeloid neoplasms after HCT and is associated with an increasing cytogenetic complexity. The acquisition of more unfavorable cytogenetic profiles likely contributes to poor outcomes. Exceptions to this trend are patients that acquire more favorable cytogenetic features than at diagnosis, resulting in potentially better response to therapy and longer survival. The significance of donor-cell-derived del(20q), a rare recurrent cytogenetic abnormality in the post-transplant setting, is not clear.