Persistence of pre-leukemic clones during first remission and risk of relapse in acute myeloid leukemia

Some patients with acute myeloid leukemia (AML) who are in complete remission after induction chemotherapy harbor persisting pre-leukemic clones, carrying a subset of leukemia-associated somatic mutations. There is conflicting evidence on the prognostic relevance of these clones for AML relapse. Here, we characterized paired pre-treatment and remission samples from 126 AML patients for mutations in 68 leukemia-associated genes. Fifty patients (40%) retained ≥1 mutation during remission at a VAF of ≥2%. Mutation persistence was most frequent in DNMT3A (65% of patients with mutations at diagnosis), SRSF2 (64%), TET2 (55%), and ASXL1 (46%), and significantly associated with older age (p < 0.0001) and, in multivariate analyses adjusting for age, genetic risk, and allogeneic transplantation, with inferior relapse-free survival (hazard ratio (HR), 2.34; p = 0.0039) and overall survival (HR, 2.14; p = 0.036). Patients with persisting mutations had a higher cumulative incidence of relapse before, but not after allogeneic stem cell transplantation. Our work underlines the relevance of mutation persistence during first remission as a novel risk factor in AML. Persistence of pre-leukemic clones may contribute to the inferior outcome of elderly AML patients. Allogeneic transplantation abrogated the increased relapse risk associated with persisting pre-leukemic clones, suggesting that mutation persistence may guide post-remission treatment.

Genetics of acute myeloid leukemia in the elderly: mutation spectrum and clinical impact in intensively treated patients aged 75 years or older

A cute myeloid leukemia is a disease of the elderly (median age at diagnosis, 65-70 years). The prognosis of older acute myeloid leukemia patients is generally poor. While genetic markers have become important tools for risk stratification and treatment selection in young and middle-aged patients, their applicability in very old patients is less clear. We sought to validate existing genetic risk classification systems and identify additional factors associated with outcomes in intensively treated patients aged ≥75 years. In 151 patients who received induction chemotherapy in the AMLCG-1999 trial, we investigated recurrently mutated genes using a targeted sequencing assay covering 64 genes. The median number of mutated genes per patient was four. The most commonly mutated genes were TET2 (42%), DNMT3A (35%), NPM1 (32%), SRSF2 (25%) and ASXL1 (21%). The complete remission rate was 44% and the 3-year survival was 21% for the entire cohort. While adverse-risk cytogenetics (MRC classification) were associated with shorter overall survival (P=0.001), NPM1 and FLT3-ITD mutations (present in 18%) did not have a significant impact on overall survival. Notably, none of the 13 IDH1-mutated patients (9%) reached complete remission. Consequently, the overall survival of this subgroup was significantly shorter than that of IDH1-wildtype patients (P<0.001). In summary, even among very old, intensively treated, acute myeloid leukemia patients, adverse-risk cytogenetics predict inferior survival. The spectrum and relevance of driver gene mutations in elderly patients differs from that in younger patients. Our data implicate IDH1 mutations as a novel marker for chemorefractory disease and inferior prognosis. (AMLCG-1999 trial: clinicaltrials.gov identifier, NCT00266136).

Multimodality therapy in subclassified stage IIIA-N2 non-small cell lung cancer patients according to the Robinson classification: heterogeneity and management

Background

Non-small cell lung cancer (NSCLC) with mediastinal lymph node involvement (N2) is a heterogeneous entity. The objective of this analysis is to investigate the results of treatment strategies for N2-positive patients.

Methods

Retrospective study (2009-2014) of 104 consecutive patients with stage IIIA-N2 NSCLC classified according to the Robinson classification (IIIA1-IIIA4) and treated within a multimodality treatment regime.

Results

The Robinson subgroups were: IIIA1 (n=27), IIIA3 (n=60) and IIIA4 (n=17). We had no stage IIIA2 samples because we did not perform an intraoperative frozen section of lymph nodes. Surgical resection with systematic lymph node dissection was performed in all patients with stage IIIA1 (n=27). After chemotherapy or chemo-/radiotherapy, 53.3% of patients in stage IIIA3 (n=32) and 11.7% of patients in stage IIIA4 (n=2) underwent surgery with curative intention. R0 was achieved in 92.6% in stage IIIA1, 93.8% in stage IIIA3 and 100% in stage IIIA4. The 30-day mortality was 3.2%. The overall median survival was 31.7 months (5-year survival was 30.5%). There were no significant differences (P=0.583) in survival regarding the Robinson subgroups. Patients who underwent tumour resection had significantly better median survival (39.8 vs. 19.6 months; P=0.014) compared to patients treated conservatively. Deviation from the interdisciplinary recommended therapy (12%) led to a reduced median survival (11.4 vs. 31.8 months; P=0.137).

Conclusions

N2-patients should be subclassified according to the Robinson classification and discussed in the tumour board. Surgical resection should be recommended in specific cases of N2-disease (non-bulky, sensitivity to systemic treatment).

Persistence of pre-leukemic clones during first remission and risk of relapse in acute myeloid leukemia

Some patients with acute myeloid leukemia (AML) who are in complete remission after induction chemotherapy harbor persisting pre-leukemic clones, carrying a subset of leukemia-associated somatic mutations. There is conflicting evidence on the prognostic relevance of these clones for AML relapse. Here, we characterized paired pre-treatment and remission samples from 126 AML patients for mutations in 68 leukemia-associated genes. Fifty patients (40%) retained ⩾1 mutation during remission at a variant allele frequency of ⩾2%. Mutation persistence was most frequent in DNMT3A (65% of patients with mutations at diagnosis), SRSF2 (64%), TET2 (55%), and ASXL1 (46%), and significantly associated with older age (P<0.0001) and, in multivariate analyses adjusting for age, genetic risk, and allogeneic transplantation, with inferior relapse-free survival (hazard ratio, 2.34; P=0039) and overall survival (hazard ratio, 2.14; P=036). Patients with persisting mutations had a higher cumulative incidence of relapse before, but not after allogeneic stem cell transplantation. Our work underlines the relevance of mutation persistence during first remission as a novel risk factor in AML. Persistence of pre-leukemic clones may contribute to the inferior outcome of elderly AML patients. Allogeneic transplantation abrogated the increased relapse risk associated with persisting pre-leukemic clones, suggesting that mutation persistence may guide postremission treatment.Leukemia accepted article preview online, 18 December 2017. doi:10.1038/leu.2017.350.

A 29-gene and cytogenetic score for the prediction of resistance to induction treatment in acute myeloid leukemia

Primary therapy resistance is a major problem in acute myeloid leukemia treatment. We set out to develop a powerful and robust predictor for therapy resistance for intensively treated adult patients. We used two large gene expression data sets (n=856) to develop a predictor of therapy resistance, which was validated in an independent cohort analyzed by RNA sequencing (n=250). In addition to gene expression markers, standard clinical and laboratory variables as well as the mutation status of 68 genes were considered during construction of the model. The final predictor (PS29MRC) consisted of 29 gene expression markers and a cytogenetic risk classification. A continuous predictor is calculated as a weighted linear sum of the individual variables. In addition, a cut off was defined to divide patients into a high-risk and a low-risk group for resistant disease. PS29MRC was highly significant in the validation set, both as a continuous score (OR=2.39, P=8.63·10⁻⁹, AUC=0.76) and as a dichotomous classifier (OR=8.03, P=4.29·10⁻⁹); accuracy was 77%. In multivariable models, only TP53 mutation, age and PS29MRC (continuous: OR=1.75, P=0.0011; dichotomous: OR=4.44, P=0.00021) were left as significant variables. PS29MRC dominated all models when compared with currently used predictors, and also predicted overall survival independently of established markers. When integrated into the European LeukemiaNet (ELN) 2017 genetic risk stratification, four groups (median survival of 8, 18, 41 months, and not reached) could be defined (P=4.01·10⁻¹⁰). PS29MRC will make it possible to design trials which stratify induction treatment according to the probability of response, and refines the ELN 2017 classification.

A fluorescence in situ hybridization-based screen allows rapid detection of adverse cytogenetic alterations in patients with acute myeloid leukemia

In adult acute myeloid leukemia (AML), the karyotype of the leukemic cell is among the strongest prognostic factors. The Medical Research Council (MRC) and the European LeukemiaNet (ELN) classifications distinguish between favorable, intermediate and adverse cytogenetic risk patients who differ in their treatment response and overall survival. Conventional cytogenetic analyses are a mandatory component of AML diagnostics but they are time-consuming; therefore, therapeutic decisions in elderly patients are often delayed. We investigated whether a screening approach using a panel of seven fluorescence in situ hybridization (FISH) probes would allow rapid identification of adverse chromosomal changes. In a cohort of 334 AML patients, our targeted FISH screening approach identified 80% of adverse risk AML patients with a specificity of 99%. Incorporating FISH screening into diagnostic workup has the potential to accelerate risk stratification and treatment selection, particularly in older patients. This approach may allow therapeutic decisions more quickly, which benefits both patients and physicians and might save costs.

Prospective, multi-center study of 5-fluorouracil (5-FU) therapeutic drug management (TDM) in metastatic colorectal cancer (mCRC) patients treated in routine clinical practice

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Background: Studies have demonstrated that body surface area (BSA)-based dosing of chemotherapy drugs leads to significant individual exposure variability with a substantial risk of under- or overdosing. This study was initiated to validate use of TDM to personalize 5-FU dosing in mCRC patients treated in routine clinical practice. Methods: 75 mCRC patients from 8 German medical centers received up to 6 administrations of infusional 5-FU according to either the AIO (n = 16), FOLFOX6 (n = 26) or FUFOX (n = 33) regimen. Initial infusional 5-FU dosing for all patients was based on BSA. Individual 5-FU exposure (AUC) was measured by an immunoassay using a blood sample drawn during each infusion. To achieve target AUC of 20 to 30 mg•h/L, subsequent infusional 5-FU doses were adjusted according to the previous cycle 5-FU AUC. Tumor markers CEA and CA19-9 were also measured before, during and after treatment. Primary objective was to confirm TDM of infusional 5-FU resulted in an increased proportion of patients in the target AUC range at the 4th versus the 1st administration. Secondary objective was to determine whether 5-FU TDM reduced treatment-related toxicities compared to historical data. Results: Average 5-FU AUC at 1st administration was 18 + 6 mg•h/L, with 64%, 33% and 3% of the patients below, within or above target AUC range, respectively. By the 4th administration average 5-FU AUC was 25 + 7 mg•h/L (p < 0.001), with 54% patients within the target 5-FU AUC range (p = 0.0294). Compared to baseline levels, CEA and CA19-9 remained stable or decreased at the end of treatment in 82% and 84% of the patients, respectively. 5-FU-related grade 3-4 diarrhea (4.6%), nausea (3.4%), fatigue (0.0%) and mucositis (0.2%) were reduced compared to historical data inspite of 55% of patients having their doses increased. Conclusions: Personalization of 5-FU dosing via TDM in routine clinical practice resulted in significantly improved 5-FU exposure and suggested lower 5-FU-related toxicities. Clinical trial information: 2011-003553-26.

[Acute myeloid Leukemia]

Acute myeloid leukemia (AML) has been genetically characterized extensively and can now be subdivided into 9 to 11 pathogenetically different subtypes according to their profile of driver mutations. In clinical practice karyotyping and molecular analysis of NPM1, cEBPa and FLT3-ITD are required for treatment stratification and potentially genotype specific treatment. Some markers such as NPM1 not only offer prognostic information but can also serve as markers of minimal residual disease and thus have the potential to guide therapy in the future.The basis of curative treatment is intensive combination chemotherapy comprizing cytarabine and an anthracycline ("7 + 3" regimen). The prolonged duration of aplasia can be reduced significantly by accelerated therapy ("S-HAM" regimen). Following achievement of a complete remission patients with a low risk of relapse - based on genetic and clinical features - receive chemotherapy based consolidation therapy whereas high risk patients - and potentially also those with an intermediate risk - receive an allogeneic stem cell transplantation. Whereas adding the rather unspecific tyrosinekinase inhibitor sorafenib to standard treatment in unselected AML patients has not improved overall survival (OS), the addition of midostaurin to standard therapy in the selected group FLT3 mutated patients has resulted in a moderate but significant OS benefit.Real world data show that in patients below 50 years a cure rate of ca. 50 % can be achieved. However less than 10 % of patients above the age of 70 will be alive after five years even after intensive treatment. Therefore when curative and intensive treatment is deemed impossible the therapeutic standard in elderly and unfit patients used to be low-dose cytarabine with an average OS of 4 months. This has now been replaced by a new standard of care of hypomethylating agents - azacytidine and decitabine - which both achieve higher remission rates and show strong trends towards a prolonged OS of between 8 and 10 months.The paradigm for genotype-specific therapy is acute promyelocytic leukemia (APL - or AML M3 in the former FAB classification). This entity used to be a problematic AML subgroup because of its frequent coagulation disturbances and potentially fatal bleeding problems. Today patients with APL can be treated with a chemotherapy free combination of ATRA - a differentiating agent - and Arsenic Trioxide - an apoptosis inducing agent. In patients with a leukocyte count < 10 000 / µl a cure rate of > 90 % can now be achieved.

Patients with Acute Myeloid Leukemia Admitted to Intensive Care Units: Outcome Analysis and Risk Prediction

Background

This retrospective, multicenter study aimed to reveal risk predictors for mortality in the intensive care unit (ICU) as well as survival after ICU discharge in patients with acute myeloid leukemia (AML) requiring treatment in the ICU.

Methods and Results

Multivariate analysis of data for 187 adults with AML treated in the ICU in one institution revealed the following as independent prognostic factors for death in the ICU: arterial oxygen partial pressure below 72 mmHg, active AML and systemic inflammatory response syndrome upon ICU admission, and need for hemodialysis and mechanical ventilation in the ICU. Based on these variables, we developed an ICU mortality score and validated the score in an independent cohort of 264 patients treated in the ICU in three additional tertiary hospitals. Compared with the Simplified Acute Physiology Score (SAPS) II, the Logistic Organ Dysfunction (LOD) score, and the Sequential Organ Failure Assessment (SOFA) score, our score yielded a better prediction of ICU mortality in the receiver operator characteristics (ROC) analysis (AUC = 0.913 vs. AUC = 0.710 [SAPS II], AUC = 0.708 [LOD], and 0.770 [SOFA] in the training cohort; AUC = 0.841 for the developed score vs. AUC = 0.730 [SAPSII], AUC = 0.773 [LOD], and 0.783 [SOFA] in the validation cohort). Factors predicting decreased survival after ICU discharge were as follows: relapse or refractory disease, previous allogeneic stem cell transplantation, time between hospital admission and ICU admission, time spent in ICU, impaired diuresis, Glasgow Coma Scale <8 and hematocrit of ≥25% at ICU admission. Based on these factors, an ICU survival score was created and used for risk stratification into three risk groups. This stratification discriminated distinct survival rates after ICU discharge.

Conclusions

Our data emphasize that although individual risks differ widely depending on the patient and disease status, a substantial portion of critically ill patients with AML benefit from intensive care.

The NPM1 mutation type has no impact on survival in cytogenetically normal AML

NPM1 mutations represent frequent genetic alterations in patients with acute myeloid leukemia (AML) associated with a favorable prognosis. Different types of NPM1 mutations have been described. The purpose of our study was to evaluate the relevance of different NPM1 mutation types with regard to clinical outcome. Our analyses were based on 349 NPM1-mutated AML patients treated in the AMLCG99 trial. Complete remission rates, overall survival and relapse-free survival were not significantly different between patients with NPM1 type A or rare type mutations. The NPM1 mutation type does not seem to play a role in risk stratification of cytogenetically normal AML.

Long-term follow-up of cytogenetically normal CEBPA-mutated AML

Background

The aim of this study was to analyze the long-term survival of AML patients with CEBPA mutations.

Patients and methods

We investigated 88 AML patients with a median age of 61 years and (1) cytogenetically normal AML (CN-AML), (2) monoallelic (moCEBPA) or biallelic (biCEBPA) CEBPA mutation, and (3) intensive induction treatment. 60/88 patients have been described previously with a shorter follow-up.

Results

Median follow-up time was 9.8 years (95% CI: 9.4-10.1 years) compared to 3.2 and 5.2 years in our former analyses. Patients with biCEBPA mutations survived significantly longer compared to those with moCEBPA (median overall survival (OS) 9.6 years vs. 1.7 years, p = 0.008). Patients ≤ 60 years and biCEBPA mutations showed a favorable prognosis with a 10-year OS rate of 81%.

Both, bi- and moCEBPA-mutated groups had a low early death (d60) rate of 7% and 9%, respectively. Complete remission (CR) rates for biCEBPA- and moCEBPA-mutated patients were 82% vs. 70% (p = 0.17). biCEBPA-mutated patients showed a longer relapse free survival (RFS) (median RFS 9.4 years vs. 1.5 years, p = 0.021) and a lower cumulative incidence of relapse (CIR) compared to moCEBPA-mutated patients. These differences in OS and RFS were confirmed after adjustment for known clinical and molecular prognostic factors.

Conclusions

In this long-term observation we confirmed the favorable prognostic outcome of patients with biCEBPA mutations compared to moCEBPA-mutated CN-AML. The high probability of OS (81%) in younger patients is helpful to guide intensity of postremission therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-014-0055-7) contains supplementary material, which is available to authorized users.

Molecular response assessment by quantitative real-time polymerase chain reaction after induction therapy in NPM1-mutated patients identifies those at high risk of relapse

Monitoring minimal residual disease is an important way to identify patients with acute myeloid leukemia at high risk of relapse. In this study we investigated the prognostic potential of minimal residual disease monitoring by quantitative real-time polymerase chain reaction analysis of NPM1 mutations in patients treated in the AMLCG 1999, 2004 and 2008 trials. Minimal residual disease was monitored - in aplasia, after induction therapy, after consolidation therapy, and during follow-up - in 588 samples from 158 patients positive for NPM1 mutations A, B and D (with a sensitivity of 10(-6)). One hundred and twenty-seven patients (80.4%) achieved complete remission after induction therapy and, of these, 56 patients (44.1%) relapsed. At each checkpoint, minimal residual disease cut-offs were calculated. After induction therapy a cut-off NPM1 mutation ratio of 0.01 was associated with a high hazard ratio of 4.26 and the highest sensitivity of 76% for the prediction of relapse. This was reflected in a cumulative incidence of relapse after 2 years of 77.8% for patients with ratios above the cut-off versus 26.4% for those with ratios below the cut-off. In the favorable subgroup according to European LeukemiaNet, the cut-off after induction therapy also separated the cohort into two prognostic groups with a cumulative incidence of relapse of 76% versus 6% after 2 years. Our data demonstrate that in addition to pre-therapeutic factors, the course of minimal residual disease in an individual is an important prognostic factor and could be included in clinical trials for the guidance of post-remission therapy. The trials from which data were obtained were registered at www.clinicaltrials.gov (#NCT01382147, #NCT00266136) and at the European Leukemia Trial Registry (#LN_AMLINT2004_230).

Combined molecular and clinical prognostic index for relapse and survival in cytogenetically normal acute myeloid leukemia

PURPOSE

Cytogenetically normal (CN) acute myeloid leukemia (AML) is the largest and most heterogeneous cytogenetic AML subgroup. For the practicing clinician, it is difficult to summarize the prognostic information of the growing number of clinical and molecular markers. Our purpose was to develop a widely applicable prognostic model by combining well-established pretreatment patient and disease characteristics.

PATIENTS AND METHODS

Two prognostic indices for CN-AML (PINA), one regarding overall survival (OS; PINAOS) and the other regarding relapse-free survival (RFS; PINARFS), were derived from data of 572 patients with CN-AML treated within the AML Cooperative Group 99 study (www.aml-score.org).

RESULTS

On the basis of age (median, 60 years; range, 17 to 85 years), performance status, WBC count, and mutation status of NPM1, CEBPA, and FLT3-internal tandem duplication, patients were classified into the following three risk groups according to PINAOS and PINARFS: 29% of all patients and 32% of 381 responding patients had low-risk disease (5-year OS, 74%; 5-year RFS, 55%); 56% of all patients and 39% of responding patients had intermediate-risk disease (5-year OS, 28%; 5-year RFS, 27%), and 15% of all patients and 29% of responding patients had high-risk disease (5-year OS, 3%; 5-year RFS, 5%), respectively. PINAOS and PINARFS stratified outcome within European LeukemiaNet genetic groups. Both indices were confirmed on independent data from Cancer and Leukemia Group B/Alliance trials.

CONCLUSION

We have developed and validated, to our knowledge, the first prognostic indices specifically designed for adult patients of all ages with CN-AML that combine well-established molecular and clinical variables and that are easily applicable in routine clinical care. The integration of both clinical and molecular markers could provide a basis for individualized patient care through risk-adapted therapy of CN-AML.

Allogeneic transplantation versus chemotherapy as postremission therapy for acute myeloid leukemia: a prospective matched pairs analysis

PURPOSE

The majority of patients with acute myeloid leukemia (AML) who achieve complete remission (CR) relapse with conventional postremission chemotherapy. Allogeneic stem-cell transplantation (alloSCT) might improve survival at the expense of increased toxicity. It remains unknown for which patients alloSCT is preferable.

PATIENTS AND METHODS

We compared the outcome of 185 matched pairs of a large multicenter clinical trial (AMLCG99). Patients younger than 60 years who underwent alloSCT in first remission (CR1) were matched to patients who received conventional postremission therapy. The main matching criteria were AML type, cytogenetic risk group, patient age, and time in first CR.

RESULTS

In the overall pairwise compared AML population, the projected 7-year overall survival (OS) rate was 58% for the alloSCT and 46% for the conventional postremission treatment group (P = .037; log-rank test). Relapse-free survival (RFS) was 52% in the alloSCT group compared with 33% in the control group (P < .001). OS was significantly better for alloSCT in patient subgroups with nonfavorable chromosomal aberrations, patients older than 45 years, and patients with secondary AML or high-risk myelodysplastic syndrome. For the entire patient cohort, postremission therapy was an independent factor for OS (hazard ratio, 0.66; 95% CI, 0.49 to 0.89 for alloSCT v conventional chemotherapy), among age, cytogenetics, and bone marrow blasts after the first induction cycle.

CONCLUSION

AlloSCT is the most potent postremission therapy for AML and is particularly active for patients 45 to 59 years of age and/or those with high-risk cytogenetics.

Influence of molecular subgroups on outcome of acute myeloid leukemia with normal karyotype in 141 patients undergoing salvage allogeneic stem cell transplantation in primary induction failure or beyond first relapse

Based on molecular aberrations, in particular the NPM1 mutation (NPM1(mut)) and the FLT3 internal tandem duplication (Flt3-ITD), prognostic subgroups have been defined among patients with acute myeloid leukemia with normal karyotype. Whereas these subgroups are known to play an important role in outcome in first complete remission, and also in the indication for allogeneic stem cell transplantation, data are limited on their role after transplantation in advanced disease. To evaluate the role of molecular subgroups of acute myeloid leukemia with normal karyotype after allogeneic stem cell transplantation beyond first complete remission, we analyzed the data from 141 consecutive adults (median age: 51.0 years, range 18.4-69.3 years) who had received an allogeneic transplant either in primary induction failure or beyond first complete remission. A sequential regimen of cytoreductive chemotherapy (fludarabine, high-dose AraC, amsacrine) followed by reduced intensity conditioning (FLAMSA-RIC), was uniformly used for conditioning. After a median follow up of three years, overall survival from transplantation was 64 ± 4%, 53 ± 4% and 44 ± 5% at one, two and four years, respectively. Forty patients transplanted in primary induction failure achieved an encouraging 2-year survival of 69%. Among 101 patients transplanted beyond first complete remission, 2-year survival was 81% among patients with the NPM1(mut)/FLT3(wt) genotype in contrast to 43% in other genotypes. Higher numbers of transfused CD34(+) cells (hazard ratio 2.155, 95% confidence interval 0.263-0.964, P=0.039) and favorable genotype (hazard ratio 0.142, 95% confidence interval: 0.19-0.898, P=0.048) were associated with superior overall survival in multivariate analysis. In conclusion, patients with acute myeloid leukemia with normal karyotype can frequently be rescued after primary induction failure by allogeneic transplantation following FLAMSA-RIC. The prognostic role of NPM1(mut)/FLT3-ITD based subgroups was carried through after allogeneic stem cell transplantation beyond first complete remission.

RUNX1 mutations in cytogenetically normal acute myeloid leukemia are associated with a poor prognosis and up-regulation of lymphoid genes

BACKGROUND

The RUNX1 (AML1) gene is a frequent mutational target in myelodysplastic syndromes and acute myeloid leukemia. Previous studies suggested that RUNX1 mutations may have pathological and prognostic implications.

DESIGN AND METHODS

We screened 93 patients with cytogenetically normal acute myeloid leukemia for RUNX1 mutations by capillary sequencing of genomic DNA. Mutation status was then correlated with clinical data and gene expression profiles.

RESULTS

We found that 15 out of 93 (16.1%) patients with cytogenetically normal acute myeloid leukemia had RUNX1 mutations. Seventy-three patients were enrolled in the AMLCG-99 trial and carried ten RUNX1 mutations (13.7%). Among these 73 patients RUNX1 mutations were significantly associated with older age, male sex, absence of NPM1 mutations and presence of MLL-partial tandem duplications. Moreover, RUNX1-mutated patients had a lower complete remission rate (30% versus 73% P=0.01), lower relapse-free survival rate (3-year relapse-free survival 0% versus 30.4%; P=0.002) and lower overall survival rate (3-year overall survival 0% versus 34.4%; P<0.001) than patients with wild-type RUNX1. RUNX1 mutations remained associated with shorter overall survival in a multivariate model including age and the European Leukemia Net acute myeloid leukemia genetic classification as covariates. Patients with RUNX1 mutations showed a unique gene expression pattern with differential expression of 85 genes. The most prominently up-regulated genes in patients with RUNX1-mutated cytogenetically normal acute myeloid leukemia include lymphoid regulators such as HOP homeobox (HOPX), deoxynucleotidyltransferase (DNTT, terminal) and B-cell linker (BLNK), indicating lineage infidelity.

CONCLUSIONS

Our findings firmly establish that RUNX1 mutations are a marker of poor prognosis and provide insights into the pathogenesis of RUNX1 mutation-positive acute myeloid leukemia.

Nature and dynamics of nucleosome release from neoplastic and non-neoplastic cells

BACKGROUND

Circulating nucleosomes are elevated in the blood of patients with malignant and non-malignant diseases. Here, we investigated the nature and the dynamics of their release in functional cell studies.

MATERIALS AND METHODS

Leukemia blasts were exposed to the intrinsic inducers of apoptotic cell death, cytosine arabinoside (AraC; 10 μg/ml) and etoposide (50 μg/ml), and cell death markers lactate dehydrogenase (LDH) and the nucleosomes were measured in the supernatants at 0, 24, 48, 72, and 96 hours after drug application. In addition, HepG2 cells were exposed to extrinsic apoptosis-inducing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL; 0.5 and 1.0 ng/ml) and the nucleosomes were measured in the supernatants after 0, 24, 48, and 72 hours. Finally, neutrophils preactivated by phorbol myristate acetate (PMA) were co-incubated with platelet-rich plasma (PRP) in the presence of collagen (type I; 8 μg/ml) for 15 or 30 minutes at 37°C, and the nucleosome release into the supernatant was quantified.

RESULTS

During treatment with AraC, cell viability constantly decreased. LDH and nucleosome levels increased at 24 h and peaked at 48 h after exposure to AraC and etoposide. While LDH declined after 96 h, the nucleosomes' levels were still elevated. Similarly, nucleosomes increased dose-dependently 24 h after exposure to TRAIL and reached a peak at 48 h. After 72 h, the nucleosomes' levels decreased again. While there was only a minor release of nucleosomes from PMA-stimulated neutrophils, co-incubation with PRP resulted in a strongly increased nucleosome release after 30 minutes.

CONCLUSION

Nucleosomes are released from cells stimulated intrinsically or extrinsically to undergo apoptotic cell death in a time- and dose-dependent manner. Further mechanisms of release may be their active secretion from stimulated neutrophils when co-incubated with PRP, as may be observed during bacterial inflammation and thrombosis.