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Improved outcomes for myeloid leukemia of Down syndrome: a report from the Children's Oncology Group AAML0431 trial.

ABSTRACT: Patients with myeloid leukemia of Down syndrome (ML-DS) have favorable event-free survival (EFS), but experience significant treatment-related morbidity and mortality. ML-DS blast cells ex vivo have increased sensitivity to cytarabine (araC) and daunorubicin, suggesting that optimizing drug dosing may improve outcomes while reducing toxicity. The Children's Oncology Group (COG) AAML0431 trial consisted of 4 cycles of induction and 2 cycles of intensification therapy based on the treatment schema of the previous COG A2971 trial with several modifications. High-dose araC (HD-araC) was used in the second induction cycle instead of the intensification cycle, and 1 of 4 daunorubicin-containing induction cycles was eliminated. For 204 eligible patients, 5-year EFS was 89.9% and overall survival (OS) was 93.0%. The 5-year OS for 17 patients with refractory/relapsed leukemia was 34.3%. We determined the clinical significance of minimal residual disease (MRD) levels as measured by flow cytometry on day 28 of induction I. MRD measurements, available for 146 of the 204 patients, were highly predictive of treatment outcome; 5-year disease-free survival for MRD-negative patients (n = 125) was 92.7% vs 76.2% for MRD-positive patients (n = 21) (log-rank P = .011). Our results indicated that earlier use of HD-araC led to better EFS and OS in AAML0431 than in past COG studies. A 25% reduction in the cumulative daunorubicin dose did not impact outcome. MRD, identified as a new prognostic factor for ML-DS patients, can be used for risk stratification in future clinical trials. This trial was registered at www.clinicaltrials.gov as #NCT00369317.

SUBMITTER: Taub JW

PROVIDER: S-EPMC5482102 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Context.—Detailed diagnostic features of acute myeloid leukemia in Down syndrome are lacking, leading to potential misdiagnoses as standard acute myeloid leukemia occurring in patients with Down syndrome.Objective.—To evaluate diagnostic features of acute myeloid leukemia and myelodysplastic syndrome in patients with Down syndrome.Design.—Diagnostic bone marrow samples from 163 patients enrolled in the Children's Oncology Group study AAML0431 were evaluated by using central morphologic review and institutional immunophenotyping. Results were compared to overall survival, event-free survival, GATA1 mutation status, cytogenetics, and minimal residual disease results.Results.—Sixty myelodysplastic syndrome and 103 acute myeloid leukemia samples were reviewed. Both had distinctive features compared to those of patients without Down syndrome. They showed megakaryocytic and erythroid but little myeloid dysplasia, and marked megakaryocytic hyperplasia with unusual megakaryocyte morphology. In acute myeloid leukemia cases, megakaryoblastic differentiation of blasts was most common (54 of 103, 52%); other cases showed erythroblastic (11 of 103, 11%), mixed erythroid/megakaryoblastic (20 of 103, 19%), or no differentiation (10 of 103, 10%). Myelodysplastic syndrome and acute myeloid leukemia cases had similar event-free survival and overall survival. Leukemic subgroups showed interesting, but not statistically significant, trends for survival and minimal residual disease. Cases with institutional diagnoses of French American British M1-5 morphology showed typical features of Down syndrome disease, with survival approaching that of other cases.Conclusions.—Myelodysplastic syndrome and acute myeloid leukemia in Down syndrome display features that allow discrimination from standard cases of disease. These distinctions are important for treatment decisions, and for understanding disease pathogenesis. We propose specific diagnostic criteria for Down syndrome-related subtypes of acute myeloid leukemia and myelodysplastic syndrome.

Project description:The US Food and Drug Administration recently announced reapproval of gemtuzumab ozogamicin (GO) for treatment of CD33-positive acute myeloid leukemia (AML), thus opening up opportunities to develop strategies for effective use of GO. In light of our recent report showing prognostic significance of CD33 splicing single nucleotide polymorphisms (SNPs), the objective of this study was to comprehensively evaluate CD33 SNPs for accurate prediction of patients with AML who are more or less likely to respond to GO. We investigated the five new CD33 SNPs (rs2455069, rs35112940, rs61736475, rs1803254, and rs201074739) for association with CD33 leukemic cell surface expression and clinical response in pediatric patients with AML enrolled in the Children's Oncology Group AAML0531 trial. We further developed a composite CD33 pharmacogenetics (PGx) score using six CD33 SNPs (CD33_PGx6_score) for association with clinical outcome. Four CD33 SNPs were associated with cell surface CD33 levels and clinical response in the GO versus no-GO arms. Therefore, the CD33_PGx6_score was built using directional genotype scores for the previously reported splicing SNP and five new SNPs. Patients with a CD33_PGx6_score of 0 or higher had higher CD33 expression levels compared with patients with a score of less than 0 (P < .001). In addition, patients with a score of 0 or higher demonstrated an improved disease-free survival in the GO versus no-GO arms (62.5% ± 7.8% v 46.8% ± 8.3%, respectively; P = .008) and a reduced risk of relapse (28.3% ± 7.2% v 49.9% ± 8.4%, respectively; P < .001). No improvement from GO was observed in patients with a CD33-PGx6_score of less than 0. Consistent results were observed across the risk groups. In this study, we report a composite CD33_PGx6_score using directional genotype scores of CD33 SNPs. Once validated, our findings hold promise for use of the CD33_PGx6_score to guide efficient use of GO in patients with AML. In addition, because the CD33_PGx6_score considers SNPs with varying abundance in different ethnic groups, it has potential for global application.

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Improved outcomes for myeloid leukemia of Down syndrome: a report from the Children's Oncology Group AAML0431 trial.

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