No abstract

Diagnostic karyotype provides the framework for risk-stratification schemes in acute myeloid leukemia (AML); however, the prognostic significance of many rare recurring cytogenetic abnormalities remains uncertain. We studied the outcomes of 5876 patients (16-59 years of age) who were classified into 54 cytogenetic subgroups and treated in the Medical Research Council trials. In multivariable analysis, t(15;17)(q22;q21), t(8;21)(q22;q22), and inv(16)(p13q22)/t(16;16)(p13;q22) were the only abnormalities found to predict a relatively favorable prognosis (P < .001). In patients with t(15;17) treated with extended all-trans retinoic acid and anthracyclinebased chemotherapy, additional cytogenetic changes did not have an impact on prognosis. Similarly, additional abnormalities did not have a significant adverse effect in t(8;21) AML; whereas in patients with inv(16), the presence of additional changes, particularly ؉22, predicted a better outcome (P ‫؍‬ .004). In multivariable analyses, various abnormalities predicted a significantly poorer outcome, namely abn(3q) (excluding t(3;5)(q25;q34)), inv(3)(q21q26)/ t(3;3)(q21;q26), add(5q)/del(5q), ؊5, ؊7, add(7q)/del(7q), t(6;11)(q27;q23), t(10; 11)(p11ϳ13;q23), other t(11q23) (excluding t(9;11)(p21ϳ22;q23) and t(11;19)(q23;p13)), t(9;22)(q34;q11), ؊17, and abn(17p). Patients lacking the aforementioned favorable or adverse aberrations but with 4 or more unrelated abnormalities also exhibited a significantly poorer prognosis (designated "complex" karyotype group). These data allow more reliable prediction of outcome for patients with rarer abnormalities and may facilitate the development of consensus in reporting of karyotypic information in clinical trials involving younger adults with AML. This study is registered at http://www.isrctn.org as ISRCTN55678797 and ISRCTN17161961. (Blood. 2010;116(3): 354-365)

Measurable residual disease (MRD; previously termed minimal residual disease) is an independent, postdiagnosis, prognostic indicator in acute myeloid leukemia (AML) that is important for risk stratification and treatment planning, in conjunction with other well-established clinical, cytogenetic, and molecular data assessed at diagnosis. MRD can be evaluated using a variety of multiparameter flow cytometry and molecular protocols, but, to date, these approaches have not been qualitatively or quantitatively standardized, making their use in clinical practice challenging. The objective of this work was to identify key clinical and scientific issues in the measurement and application of MRD in AML, to achieve consensus on these issues, and to provide guidelines for the current and future use of MRD in clinical practice. The work was accomplished over 2 years, during 4 meetings by a specially designated MRD Working Party of the European LeukemiaNet. The group included 24 faculty with expertise in AML hematopathology, molecular diagnostics, clinical trials, and clinical medicine, from 19 institutions in Europe and the United States.

BACKGROUNDDespite the molecular heterogeneity of standard-risk acute myeloid leukemia (AML), treatment decisions are based on a limited number of molecular genetic markers and morphology-based assessment of remission. Sensitive detection of a leukemia-specific marker (e.g., a mutation in the gene encoding nucleophosmin [NPM1]) could improve prognostication by identifying submicroscopic disease during remission. METHODSWe used a reverse-transcriptase quantitative polymerase-chain-reaction assay to detect minimal residual disease in 2569 samples obtained from 346 patients with NPM1-mutated AML who had undergone intensive treatment in the National Cancer Research Institute AML17 trial. We used a custom 51-gene panel to perform targeted sequencing of 223 samples obtained at the time of diagnosis and 49 samples obtained at the time of relapse. Mutations associated with preleukemic clones were tracked by means of digital polymerase chain reaction. RESULTSMolecular profiling highlighted the complexity of NPM1-mutated AML, with segregation of patients into more than 150 subgroups, thus precluding reliable outcome prediction. The determination of minimal-residual-disease status was more informative. Persistence of NPM1-mutated transcripts in blood was present in 15% of the patients after the second chemotherapy cycle and was associated with a greater risk of relapse after 3 years of follow-up than was an absence of such transcripts (82% vs. 30%; hazard ratio, 4.80; 95% confidence interval [CI], 2.95 to 7.80; P<0.001) and a lower rate of survival (24% vs. 75%; hazard ratio for death, 4.38; 95% CI, 2.57 to 7.47; P<0.001). The presence of minimal residual disease was the only independent prognostic factor for death in multivariate analysis (hazard ratio, 4.84; 95% CI, 2.57 to 9.15; P<0.001). These results were validated in an independent cohort. On sequential monitoring of minimal residual disease, relapse was reliably predicted by a rising level of NPM1-mutated transcripts. Although mutations associated with preleukemic clones remained detectable during ongoing remission after chemotherapy, NPM1 mutations were detected in 69 of 70 patients at the time of relapse and provided a better marker of disease status. CONCLUSIONSThe presence of minimal residual disease, as determined by quantitation of NPM1-mutated transcripts, provided powerful prognostic information independent of other risk factors.

An internal tandem duplication in the fms-like tyrosine kinase 3 gene (FLT3/ITD) is associated with poor prognosis in acute myeloid leukemia (AML), but the impact of mutant level, size, and interaction with nucleophosmin 1 (NPM1) mutations remains controversial. We evaluated these characteristics in a large cohort of young adult AML patients. There was a highly significant trend for worsening in relapse risk (RR) and overall survival (OS) with increasing FLT3/ITD mutant level (P < .001 for both), and even in the low level mutant group (1%-24% of total FLT3 alleles), RR was significantly worse than in the FLT3 wild-type (WT) group (P < .001). In multivariate analysis, mutant level was the most powerful prognostic factor for RR. Mutant size and number had no significant impact on outcome. The beneficial impact of an NPM1 mutation on RR and OS was seen in FLT3/ITD(+) as well as FLT3/WT patients; both markers were highly significant independent predictors of outcome (P < .001). Stratification using both markers identified 3 prognostic groups: good (FLT3/ITD(-)NPM1(+)), intermediate (FLT3/ITD(-)NPM1(-) or FLT3/ITD(+)NPM1(+)), and poor (FLT3/ITD(+)NPM1(-)). Patients with high FLT3/ITD mutant level (greater than 50%) or FLT3/ITD(+) in the absence of an NPM1 mutation may be good candidates for more experimental therapeutic approaches.