Acute myeloid leukemia with t(8;21)(q22;q22) is characterized by considerable clinical and biological heterogeneity leading to relapse in up to 40% of patients. We sequenced coding regions or hotspot areas of 66 recurrently mutated genes in a cohort of 331 t(8;21) patients. At least 1 mutation, in addition to t(8;21), was identified in 95%, with a mean of 2.2 driver mutations per patient. Recurrent mutations occurred in genes related to RAS/RTK signaling (63.4%), epigenetic regulators (45%), cohesin complex (13.6%), MYC signaling (10.3%), and the spliceosome (7.9%). Our study identified mutations in previously unappreciated genes: GIGYF2, DHX15, and G2E3. Based on high mutant levels, pairwise precedence, and stability at relapse, epigenetic regulator mutations were likely to occur before signaling mutations. In 34% of RAS/RTKmutated patients, we identified multiple mutations in the same pathway. Deep sequencing (∼42 000×) of 126 mutations in 62 complete remission samples from 56 patients identified 16 persisting mutations in 12 patients, of whom 5 lacked RUNX1-RUNX1T1 in quantitative polymerase chain reaction analysis. KIThigh mutations defined by a mutant level ≥25% were associated with inferior relapse-free survival (hazard ratio, 1.96; 95% confidence interval, 1.22-3.15; P = .005). Together with age and white blood cell counts, JAK2, FLT3-internal tandem duplicationhigh, and KIThigh mutations were identified as significant prognostic factors for overall survival in multivariate analysis. Whole-exome sequencing was performed on 19 paired diagnosis, remission, and relapse trios. Exome-wide analysis showed an average of 16 mutations with signs of substantial clonal evolution. Based on the resemblance of diagnosis and relapse pairs, genetically stable (n = 13) and unstable (n = 6) subgroups could be identified.

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The clinical results in 107 patients receiving a peripheral blood stem cell (PBSC) graft mobilized by granulocyte colonystimulating factor (G-CSF) from HLA-A, -B, and -DR-compatible unrelated donors were compared to 107 matched controls receiving unrelated bone marrow (BM) transplants. Engraftment was achieved in 94% of the patients in both groups. The PBSC graft contained significantly more nucleated cells, CD34 ؉ , CD3 ؉ , and CD56 ؉ cells (P < .001), and resulted in a significantly shorter time-to-neutrophil (15 versus 19 days) and platelet engraftment (20 versus 27 days), compared to the BM control group (P < .001). Probabilities of acute graft-versus-host disease (GVHD) grades II to IV were 35% and 32% (not significant [NS]) and of chronic GVHD 61% and 76% (NS) in the PBSC and BM groups, respectively. There was no difference between the 2 groups in bacteremia, cytomegalovirus reactivation or disease, and fungal infection. The 3-year transplant-related mortality (TRM) rates were 42% in the PBSC group and 31% in the BM controls (P ‫؍‬ .7) and the survival rates were 46% and 51%, respectively. The probability of relapse was 25% and 31% in both groups (NS), resulting in diseasefree survival rates of 43% in the PBSC group and 46% in the BM controls (NS). In the multivariate analysis, early disease, acute GVHD grade 0 to I, and presence of chronic GVHD were independent factors associated with a better disease-free survival in this study. PBSC from HLAcompatible unrelated donors can be used safely as an alternative to BM for stem cell transplantation. (Blood. 2001;98: 1739-1745)