Low-risk Acute Myeloid Leukemia Research Articles

High expression of microRNA-500 is associated with poor prognosis in patients with acute myeloid leukemia receiving allogeneic hematopoietic stem cell transplantation.

MicroRNA-500 (miR-500) is a potential prognostic biomarker in a number of different types of cancer, such as prostate cancer and hepatocellular carcinoma. This study aimed to explore the clinical implications of miR-500 expression status in patients with acute myeloid leukemia (AML) that had received allogeneic hematopoietic stem cell transplantation (allo-HSCT). miR-500 expression status and clinical data were obtained from 74 patients with AML in the The Cancer Genome Atlas database receiving allo-HSCT. Patients with low expression level of miR-500 (miR-500low) were significantly more likely to present with a French-American-British classification M2 subtype (P=0.003), and less likely to have the M5 subtype (P=0.040) compared with patients with high expression levels (miR-500high). miR-500low patients were associated with low-risk AML (P=0.003) and core-binding factor subunit b-myosin heavy chain 11 translocation mutation (P=0.021). There was a significant difference in nucleophosmin 1 (P=0.009), NRAS proto-oncogene GTPase/KRAS proto-oncogene GTPase (P=0.047) and PHD finger protein 6 (P=0.040) expression levels between the two groups. miR-500high patients had a decreased overall survival (OS) time compared with the low expression group (P=0.035). Multivariate analysis revealed that miR-500 expression significantly affected OS time independent of other classical prognostic factors, such as age and common mutations. The analysis of survival curves further substantiated this result. The results obtained in the current study suggested that miR-500 may be a suitable prognostic marker for patients with AML receiving allo-HSCT.

Microtransplantation: clinical applications and mechanisms.

Microtransplantation (MST) has been successfully used to manage patients with hematological malignancies, especially older patients with acute myeloid leukemia (AML). Recent clinical applications and mechanistic studies of MST are reviewed. MST improves complete remission rates which have no significant difference among age groups in older patients with AML. Sufficient courses of postremission therapy lead to prolonged overall survival and reduced relapse rate. MST also benefits young patients with low-risk or intermediate-risk AML who lack a human leukocyte antigen-identical donor and shows therapeutic potential extending to other malignancies. Both donor and recipient-derived T cells contribute to the antileukemic effect. Novel methods to monitor donor microchimerism and donor-recipient immune cell interaction may further unveil mechanisms of MST. MST shows therapeutic efficacy to several hematological malignancies, whereas mechanistic studies still need to be promoted, and its combination with other targeted therapies is warranted to further reduce relapse rate.

Four versus five chemotherapy courses in patients with low risk acute myeloid leukemia: A Children’s Oncology Group report.

10515 Background: For pediatric patients with low risk (LR) acute myeloid leukemia (AML), the Children’s Oncology Group (COG) trial AAML1031 used a 4-course chemotherapy backbone consisting of two induction courses of cytarabine/daunorubicin/etoposide, a third course of cytarabine/etoposide and a fourth course of cytarabine/mitoxantrone. The prior COG trial, AAML0531, included the same four courses plus a fifth course of high dose cytarabine. Removal of course 5 from AAML1031 was based in part on prior studies that suggested no benefit from a fifth course. Methods: We compared overall survival (OS), disease free survival (DFS), and relapse risk (RR) for LR patients receiving four versus five chemotherapy courses in a pooled analysis of comparable patients treated on AAML0531 and AAML1031. LR was defined as the presence of inv(16)/t(16;16) or t(8;21) cytogenetic features, NPM1 or CEBPA mutations, or MRD < 0.1% post-Induction I in those with no high risk features. AAML0531 patients assigned to gemotuzumab were excluded. Follow-up for outcomes began at the start of course 4. Cox (OS and EFS) and risk (RR) regressions were used to estimate unadjusted hazard ratios (HR) comparing outcomes for patients who received only four versus five chemotherapy courses. Start of a fifth chemotherapy course was assessed as a time-varying exposure in all analyses to avoid exposure misclassification. Results: A total of 921 LR patients (225 from AAML0531, 696 from AAML1031) were included; 191 (21%) received a fifth course. There were no significant differences in distributions of sex, age, race, or ethnicity between patients treated with four or five courses. Median times to absolute neutrophil count and platelet count recovery after course 4 were also comparable. Patients who received only four courses had significantly lower OS (HR = 1.83, 95% CI: 1.22-2.74, p = 0.003), DSF (HR = 1.49, 95% CI: 1.13-1.97, p = 0.005), and higher RR (HR = 1.42, 95% CI: 1.08-1.88, p = 0.013) compared to those who received five courses. Conclusions: Removal of a fifth cytarabine-containing course appears to result in worse OS, DFS, and RR in pediatric patients with LR AML. Multivariable analyses to further refine the estimates are ongoing.

Intensified induction therapy with reduced total anthracycline exposure in pediatric low-risk acute myeloid leukemia.

10533 Background: Despite advances in risk stratification and therapy, the post-induction disease free survival (DFS) and overall survival (OS) for children with low-risk acute myeloid leukemia (LR-AML) remain low with DFS and OS of 50% and 68%, respectively, on the standard arm of the recent Children’s Oncology Group (COG) trial, AAML1031. Additionally, current therapy for pediatric LR-AML contains anthracycline doses exceeding thresholds known to increase the risk of adverse cardiac effects. In an effort to decrease exposure to cardiotoxic therapy, the Aflac Cancer and Blood Disorders Center adopted an institutional practice to treat LR-AML patients with a regimen of intensified induction therapy with decreased anthracycline exposure (Aflac-AML consisting of ADE10, Mitox/HiDAC, HiDAC/VP, Capizzi II). The aim of this study is to describe the associated toxicities and outcomes of this regimen in pediatric LR-AML. Methods: We retrospectively reviewed medical records of patients diagnosed with de novo LR-AML and treated per the Aflac-AML regimen from 2011-2014. Charts were reviewed for cardiac outcomes, ICU admissions, and the rate of infectious toxicities. DFS and OS were determined using Kaplan-Meier survival analysis. Results: We identified 11 LR-AML patients treated with Aflac-AML therapy. Patients received a planned 317 mg/m2 cumulative anthracycline dose vs 442 mg/m2for those treated on AAML1031. There was no decrease in LVEF with a mean change of +2.17% for Aflac-AML patients from the time of diagnosis to therapy completion (p = 0.23). The primary infectious toxicities observed were febrile neutropenia and bacterial infections with a median of 36.4±6% documented bacterial infections per cycle. Fungal and viral infections were rare as were ICU admissions – median 4.5±4% per cycle – and there were no toxic mortalities. The 3-year DFS and OS from end of induction I for Aflac-AML patients were 72.7% and 90.9%, respectively. Conclusions: The Aflac-AML regimen resulted in short-term toxicities and outcomes comparable to current chemotherapy regimens for pediatric LR-AML but with reduced anthracycline exposure. These data support use of this regimen for pediatric LR-AML patients.

Prognostic Impact of ABCA3 Expression in Pediatric Acute Myeloid Leukemia

Abstract Background. Despite progress in the molecular and genetic classification of pediatric acute myeloid leukemia (AML), the prognosis remains heterogeneous. The ATP-binding cassette transporter A3 (ABCA3) seems specifically involved in the resistance of pediatric AML to intensive chemotherapy. However, studies having investigated the prognostic impact of ABCA3 expression have yielded conflicting results with respect to patient outcomes while the small sample size of these studies precluded the use of multivariate analysis. Here we investigated the prognostic impact of ABCA3 expression in a representative series of homogeneously treated pediatric AML. Methods. Samples derived from 233 patients with available high-quality RNA and enrolled in the ELAM2 protocol (NCT00149162). qRTPCR amplification of 2 conserved ABCA3 mRNA sequences was performed with GUS and ABL as reference genes. Primer sets were complementary to exons 6-7 and exons 19-20 junctions. Patients were classified according to their standardized cytogenetic and molecular (NPM1 mutations, FLT3-ITD, CEBPA double mutations) risk subgroups (Rubnitz JE, Blood 2012;119:5980-5988, Creutzig U, Blood 2012;120:3187-3205). Treatment consisted of 1 induction course (AraC and mitoxantrone) and 3 consolidation courses (course 1 and 3 with high dose AraC); all children with either intermediate or high-risk disease were candidates for hematopoietic stem cell transplant (HSCT) in complete remission (CR) after 1 to 2 consolidation courses. Results. The discovery cohort included 120 patients. Median age, median WBC, CR rate, relapse rate, median follow-up, 5-years EFS, DFS, and OS were 9.4 years, 19.3 G/L, 95%, 29%, 60 months, 58±6%, 61±6%, and 71±5 months, respectively. The two primer sets yielded consistent results (R=0.9, p<10-4, Spearman Rank Correlation). Lower ABCA3 expression was positively associated with CBFB-MYH11 AML (p=0.002) and thereby with favorable cytogenetics (p=0.036) and low-risk AML (p=0.027). Higher ABCA3 expression was associated with higher relapse rate (p=0.006), shorter EFS (5-years, 34±9 vs 61±6 % p=0.0005), DFS (36±9 vs 62±6% p=0.0028), and OS (49±12 vs 79.5±5% p=0.0007). Multivariate analyses identified age, WBC, risk group, and ABCA3 expression as independent prognostic factors for EFS, DFS, and OS (Table 1). The validation cohort included 113 patients in whom the proportions of AML1-ETO- and MLL-positive AML were significantly higher than in the discovery cohort: 26,5% vs 6,7% (p<10-4) and 24.8 vs 14.2% (p=0.03). There was no significant difference in patients' outcome between the 2 cohorts. Using the same cutoff value in the validation cohort, higher ABCA3 expression remained significantly associated with shorter 5-years EFS: 63±7% vs 43±9% (p=0.025) with a trend for shorter DFS: 45±9 vs 53±11% (p=0.065). Multivariate analyses identified ABCA3 expression as an independent negative prognostic factor for EFS and DFS (Table 1). In the entire patients population, ABCA3 expression independently predicted EFS, DFS, and OS (not shown). In the low- (n=74) and adverse-risk (n=59) groups, higher ABCA3 expression remained associated with shorter 5-years EFS (low: 46±12 vs 75±7%, p=0.006; adverse: 12±10 vs 44±16%, p=0.018), DFS (low: 49±13 vs 75±7%; high: 12±11 vs 45±16%, p=0.016), and OS (low: 76±10 vs 94±4%; adverse: 32±14 vs 57±18%, p=0.046). Conclusion. ABCA3 expression represents an independent prognostic factor in pediatric AML. As they indicate that the level of ABCA3 expression is significantly associated with survival for currently accepted cytogenetic and molecular prognostic categories, our findings suggest that assessing ABCA3 expression will permit a better assessment of disease risk. Finally our results suggest that inhibiting ABCA3 expression, such as with indomethacin, could be beneficial in order to overcome drug resistance in pediatric AML. Disclosures No relevant conflicts of interest to declare.

Two or More Chemotherapy Consolidation Courses, Followed By Autologous Bone Marrow Transplantation, and MRD Negativity, Give Long Term Overall Survival in Acute Myeloid Leukemia Patients

Introduction. Autologous Bone Marrow Transplantation (Auto-BMT) is currently rarely used in the treatment of Acute Myeloid Leukemia (AML). However, it may represent a good therapeutic option in a specific subset of patients, mainly in consolidation of both low risk (LR) and MRD negative AML without an available HLA matched donor.Aims. To review our database of AML patients who received Auto-BMT from 2005 to 2014 and who were referred to Bologna Institution, in order to assess the efficacy of the procedure in terms of Overall Survival (OS) and Disease Free Survival (DFS).Patients and methods: From 2005 to 2014, 98 AML patients underwent Auto-BMT in several Italian Institutions. 89/98 patients are evaluable for survival and outcome data. The 89 patients considered (42 female, 47 male), had a median age of 49 years (range 15-70). Cytogenetics was performed in all patients by conventional karyotype (22 patients were also analyzed by Single Nucleotide Polymorphisms Array); molecular analysis (FLT3 TKD and ITD, and NPM1 mutational analysis) was available for 51/89 patients. Molecular monitoring by specific fusion transcripts (CBF-MYH11 and AML1-ETO) was performed in CBF positive leukemias (inv(16) and t(8;21)) at the time of diagnosis, after induction, consolidation courses, and every 3 months in the first 2 years of follow-up. Based on this data, and according to ELN guidelines, a risk stratification identified 41 patients with a LR AML (t(8:21), inv(16) or NPM1+/FLT3- with normal karyotype), 4 patients with a high risk (HR) AML (complex karyotype or FLT3 ITD mutated or inv(3) or t(6;9)) and 44 patients with a standard risk (SR) AML (normal karyotype, other alterations).Results. All the patients received an induction chemotherapy treatment, as follows: a "3+7-like" course in 48 cases, a Fludarabine-based regimen in 20 patients and a Gemtuzumab-ozogamicin (GO)-based regimen in 21. 83/89 (93.3%) patients received a median of 2 consolidation courses of chemotherapy (range 1-4) before proceeding to Auto-BMT, performed in 1st CR. 6/89 (6.7%) patients received Auto-BMT in first relapse.41 patients relapsed after auto-BMT and were treated with a re-induction chemotherapy, or were enrolled in clinical trials. 24 patients reached a 2nd complete remission, and 12 patients underwent an allogeneic BMT in 2nd CR.With a median follow up of 6 years, the median Overall Survival (OS) of the entire population was 64.3 months (range 5.8-294.2 months); the 1 year OS and the 5 years OS were, 97.1%, and 67.9%, respectively. The median Disease Free Survival (DFS) of the 83 patients treated with Auto-BMT in 1st CR was 36 months (range 1.3-293 months). The 1-year DFS and the 5-years DFS were 85% and 56.7%, respectively. Transplant related mortality (TRM, death in 100 days after BMT) was 1.2% for auto-BMT and 6.5% for allogeneic BMT.First, to assess the role of the number of consolidation courses we compared patients who received none or 1 consolidation course with patients who received 2 or more cycles, who showed a better OS (p= 0.0061, Figure 1). There was no statistical difference in terms of OS between young and elderly patients (cut off=65 years).Second, we compared patients who achieved a negative minimal residual disease status before auto-BMT (n=37) with patients who did not (n=9). MRD negativity offered a significantly better outcome in terms of 5-years OS (83.4% and 50% respectively); the median OS of MRD neg was not yet reached; the median OS of MRD pos was 27 months (p= 0.0130) (Figure 2).Conclusions: Auto-BMT offers a chance to achieve long-term DFS and OS if used as a consolidation therapy both in patients with LR and SR AML. The major role could be played in MRD negative patients, offering the best chances to achieve a long-term OS. Auto-BMT can be also a good choice as consolidation therapy for elderly patients, in which allo-BMT could induce high morbidity and mortality rates. The small patients cohort and the retrospective analysis don't allow us to define the best induction therapy to be used before auto-BMT. However, based on our findings we suggest a therapy schedule including two or more consolidation courses in patients who obtain a first CR, and to proceed then to auto-BMT.Acknowledgments: work supported by ELN, AIL, AIRC, Progetto Regione-Università 2010-12 (L.Bolondi), Fondazione del Monte di Bologna e Ravenna, FP7 NGS-PTL project. [Display omitted] [Display omitted] DisclosuresSoverini:Novartis, Briston-Myers Squibb, ARIAD: Consultancy. Rodeghiero:Celgene Corporation: Honoraria, Research Funding. Cavo:Janssen-Cilag, Celgene, Amgen, BMS: Honoraria. Martinelli:AMGEN: Consultancy; Novartis: Consultancy, Speakers Bureau; Ariad: Consultancy; BMS: Consultancy, Speakers Bureau; ROCHE: Consultancy; Pfizer: Consultancy; MSD: Consultancy.

Effect of chronic graft versus host disease on relapse and survival in patients with acute myeloid leukemia

目的探讨慢性移植物抗宿主病(cGVHD)对造血干细胞移植(HSCT)后急性髓系白血病(AML)患者复发及生存的影响。方法回顾性分析接受异基因外周血HSCT的55例发生cGVHD及未发生cGVHD的AML患者复发及生存情况。结果cGVHD组移植后2年内的AML复发率显著低于未发生cGVHD组（8.7%对38.6%，P=0.019），而2年后远期复发率与对照组比较差异无统计学意义（22.8%对5.9%，P=0.217）；移植后2年内的生存率差异无统计学意义（78.3%、61.0%，P=0.155），远期生存率cGVHD组明显降低（63.7%对100%，P=0.011）。在难治复发的高危AML患者中，cGVHD组与未发生cGVHD组比较，移植后2年内AML复发率低（8.3%对46.2%，P=0.044），生存率高（83.3%对47.2%，P=0.045）；在中低危AML患者中，有或无cGVHD其复发率及生存率均无显著变化(P=0.266，P =0.289）。局限型及广泛型cGVHD患者中，移植后复发率分别为27.3%和31.3%，较未发生cGVHD患者复发率(42.2%)均下降；但广泛型cGVHD患者远期生存率降低（53.3%，P=0.001）。结论cGVHD降低AML复发的保护作用主要发生在移植后早期（2年），尤其使得难治复发的高危AML患者受益；而在移植晚期，cGVHD尤其广泛型cGVHD与移植相关死亡率相关，明显降低远期生存率。

IDH mutations in acute myeloid leukemia

Acute myeloid leukemia is a heterogeneous group of diseases. Mutations of the isocitrate dehydrogenase (IDH) genes represent a novel class of point mutations in acute myeloid leukemia. These mutations prevent oxidative decarboxylation of isocitrate to α-ketoglutarate and confer novel enzymatic activity, facilitating the reduction of α-ketoglutarate to d-2-hydroxyglutarate, a putative oncometabolite. IDH1/IDH2 mutations are heterozygous, and their combined frequency is approximately 17% in unselected acute myeloid leukemia cases, 27% in cytogenetically normal acute myeloid leukemia cases, and up to 67% in acute myeloid leukemia cases with cuplike nuclei. These mutations are largely mutually exclusive. Despite many similarities of IDH1 and IDH2 mutations, it is possible that they represent distinct molecular or clinical subgroups of acute myeloid leukemia. All known mutations involve arginine (R), in codon 132 of IDH1 or codon 140 or 172 of IDH2. IDH1(R132) and IDH2(R140) mutations are frequently accompanied by normal cytogenetics and NPM1 mutation, whereas IDH2(R172) is frequently the only mutation detected in acute myeloid leukemia. There is increasing evidence that the prognostic impact of IDH1/2 mutations varies according to the specific mutation and also depends on the context of concurrent mutations of other genes. IDH1(R132) mutation may predict poor outcome in a subset of patients with molecular low-risk acute myeloid leukemia, whereas IDH2(R172) mutations confer a poor prognosis in patients with acute myeloid leukemia. Expression of IDH1/2 mutants induces an increase in global DNA hypermethylation and inhibits TET2-induced cytosine 5-hydroxymethylation, DNA demethylation. These data suggest that IDH1/2 mutations constitute a distinct mutational class in acute myeloid leukemia, which affects the epigenetic state, an important consideration for the development of therapeutic agents.

Identification of Differential Methylation Markers Among Cytogenetic Risk Groups of Acute Myeloid Leukemia

Abstract 1464Aberrant DNA methylation has been shown as an important mechanism in the progression from myelodysplasia (MDS) to acute myeloid leukemia (AML), leading to use of the demethylating agents, 5-azacitidine and decitabine, for treatment of both disorders. While these drugs produce responses, the ability to distinguish potential responders from potential non-responders remains limited. The purpose of this work was to bring new technology to study this problem. Recent studies demonstrated that promoter DNA methylation is not randomly distributed in AML blasts but rather is highly organized and associated with biologically distinct AML subtypes. Because cytogenetics at presentation is the most important prognostic factors in predicting response to therapy, remission duration and overall survival in AML, we aimed to identify differentially methylated genomic regions (DMR) in cytogenetically defined risk groups of AML. Published literature suggested that the new comprehensive high-throughput array-based relative methylation analysis (CHARM) has the highest sensitivity and specificity among all the array-based genome profiling methods and should be the most accurate means to identify methylation markers. It is a customized NimbleGen HD2 array of tiled 50mer-probes typically separated by 30–40 bases covering approximately 4.6 million CpG sites across the genome. This assay is highly quantitative for approximately 100,000 independent CpG sites.We performed methylation profiling with CHARM on 15 age-matched patients divided into 3 groups (n=5 in each): (1) high-risk AML, defined as patients with a complex or monosomal karyotype, inv(3)/t(3;3), t(6;9), or FLT3-ITD; (2) intermediate-risk AML, defined as patients with normal karyotype, trisomy 8, t(9;11), or others; (3) low-risk AML, defined as patients with t(8;21) or inv(16). Five age-matched normal individuals served as control. Randomly fractionated DNA was divided into two equal portions with and without McrBC treatment, which cleaves methylated DNA, then size-fractionated, purified and subject to whole-genome amplification prior to hybridization with the CHARM array. Data analysis was performed with R and Bioconductor. AML patients showed a very strong hypermethylation signature as compared with the normal control blood. A unique set of DMRs was identified which distinguishes between any two risk groups. The number of DMRs and those with p -values < 0.01 are shown in Table 1. There were fewer methylation discriminators between low- and mid-risk groups than between high-risk and the other risk groups. Figure 1 shows the comparison between high-risk group and other risk groups highlighting the 12 top DMRs with lowest p -values. In silico validation of the DMRs identified by CHARM verified previously reported aberrant hypermethylation of tumor suppressor genes like p15CDKN2B, discriminating normal from AML patients, CDH1 promoter hypermethylation in high-risk AML compared with mid-risk AML, and HOXB3 hypomethylation in mid-risk AML compared with both low-risk and high-risk AML, etc. Technical validation using quantitative bisulfite pyrosequencing on 8 genes, including DCC, DUOX2, NEFL, and PITX1, demonstrated an 87.5% concordant rate with CHARM. Testing of additional AML samples with validated markers are underway to confirm the top DMRs identified, which may serve as useful biomarkers to predict response to azacitidine and decitabine.Table 1Number of DMRsNumber with p-value < 0.01Normal blood VS at risk3768311Low-risk VS mid-risk156530Low-risk VS high-risk247573Mid-risk VS high-risk2651107 [Display omitted] Disclosures:No relevant conflicts of interest to declare.

Prevalence and Clinical Implications of N-RAS Mutations in Childhood AML – A Report From the Children's Oncology Group.

Abstract 3115Poster Board III-52Mutations in the RAS proto-oncogenes are frequent in acute myeloid leukemia (AML) and serve as prototypic Class I lesions, initiating key downstream hyper-proliferative signal transduction pathways. N-RAS mutations (N-RASmut) are common in AML, occurring in 10-20% of adult and pediatric AML patients; however their prognostic significance in both adults and children remains disputed. Due to a frequent association with a normal karyotype, delineating the impact of these mutations on outcome may enable appropriate risk-adapted therapeutic approaches. Here, we report on the incidence and prognostic significance of N-RASmut in a cohort of 825 pediatric AML patients treated on 2 recent co-operative group studies, CCG-2961 and COG AAML03P1. In total, of the 825 children with de novo AML who underwent N-RAS mutational analysis, 86 (10%) were positive. Gender, age, race, presence of hepatosplenomegaly and FAB subtype were comparable between patients with and without N-RASmut. There was no statistically significant difference between those with and without N-RASmut with respect to specific chromosome class. FLT3/Internal tandem duplications (FLT3/ITD) were less common in those with N-RASmut (2% vs. 9%, p=0.03). In contrast, nucleophosmin (NPM) mutations were more common in those with N-RASmut (13% vs. 5%, p=0.02). Overall, N-RASmut showed a significant correlation with low risk AML (CBF, CEBPαa, or NPM, p=0.04) and an inverse relationship with high risk disease (-5/5q- or -7, FLT3/ITD/high allelic ratio, p=0.007). Patients with N-RASmut had similar complete remission (CR) rates following two courses of induction chemotherapy compared with non-mutated patients (79% vs. 79%, p=0.92). Those in CR had a similar relapse rate regardless of the presence of N-RASmut (RR 39% vs. 36%, p=0.97). Five year event free survival (EFS) and overall survival (OS) from study entry were also comparable, however N-RASmut patients demonstrated a marked increase in overall treatment related mortality (TRM) (21% vs. 14%, p=0.03), which was maintained when high and low risk patients were excluded (22% vs. 11%, p=0.05). Evaluation of TRM in CCG-2961 compared with COG AAML03P1 demonstrated that increased TRM in N-RASmut was only seen in patients treated on CCG-2961 and TRM was primarily due to invasive fungal and gram negative infections. Interestingly, for patients treated on CCG-2961, who received interval compressed intensive induction therapy, this increase in TRM correlated with a decrease in both OS and disease free survival from CR. Remission specimens from patients with N-RASmut were negative for the mutation, demonstrating that an increased infectious risk could not be attributed to a host polymorphism. We found N-RASmut did not contribute to increased disease recurrence in pediatric AML. Our findings indicate that N-RAS mutations do not identify a high risk population, however, as such mutations lead to downstream activation of signal transduction pathways, they may identify a target for directed therapy. DisclosuresNo relevant conflicts of interest to declare.

Should Hematopoietic Stem Cell Transplantation in First Complete Remission Be Restricted to High-Risk Patients in Childhood Acute Myeloid Leukemia?.

Hematopoietic stem cell transplantation (HSCT) has been used as an effective consolidation therapy for children with acute myeloid leukemia (AML) in first complete remission (CR). Although it is effective in relapse prevention, often it causes severe late sequelae, such as short stature and infertility. There is a recent trend to restrict the use of HSCT in first CR for high-risk patients. However, there is no study comparing which strategy is better, risk-adapted or general recommendation for HSCT in AML children in first CR. In our institutes, all such children in first CR were recommended either allogeneic or autologous HSCT until 1997. After 1998, patients were classified into three risk-groups. Low-risk patients (t(8;21) and inv(16)) were not recommended to undergo HSCT. High-risk patients (−7, 5q-, Ph1, t(16;21) and remission failure) were recommended to undergo HSCT. Intermediate-risk (other karyotypes) patients received HSCT in first CR if a suitable donor was available. In this study, we retrospectively compared the prognosis of 66 patients who were diagnosed with de novo AML between 1991 and 1997 (group A; n=37) and between 1998 and 2003 (group B; n=29). AML with Down syndrome and AML-M3 were excluded. The median (range) age was five (0–15) years. FAB classifications were M0 (n = 1), M1 (n = 10), M2 (n = 22), M4 (n = 6), M4E (n = 5), M5 (n = 14), M6 (n = 0), and M7 (n = 8). Chromosome analysis data were t(8;21) (n = 18), inv(16) (n = 4), 11q23 (n = 10), other abnormalities (n = 14), normal karyotype (n = 14), and unknown (n = 6). Induction chemotherapy comprised VP-16, cytarabine, and mitoxantrone. Sixty-three of 66 patients (95.5%) achieved CR. HSCT in first CR was done in 24 patients (64.9%) in group A and seven patients (24.1%) in group B (p = 0.0044). Age, sex, WBC count at diagnosis, FAB classification and chromosomal abnormalities did not differ between the two groups. Fourteen (five in group A and nine in group B) patients relapsed. Six (three in group A and three in group B) of them were salvaged by HSCT. Both 5-year event-free survival (EFS) and overall survival (OS) were statistically higher in group A than in group B (5-year EFS: 83.8 ± 6.1% versus 62.1 ± 9.0%, p = 0.0404; 5-year OS: 91.6 ± 4.7% versus 71.6 ± 8.5%, p = 0.0364). Although intensified chemotherapy without HSCT for low-risk AML patients is desirable to avoid the late complications of HSCT, our analysis showed that the introduction of risk-stratified treatment strategy significantly worsened the chances of EFS and OS. Our risk stratification based on chromosomal abnormalities only may be insufficient to identify low-risk AML children. Development of more sophisticated risk classification, including molecular markers, may be required to identify true low-risk patients who should avoid HSCT in first CR.

Consolidation therapy for adult acute myeloid leukemia: A systematic analysis according to evidence based medicine

Post-remission therapy in acute myeloid leukemia (AML) remains problematic. It has been demonstrated that younger patients can maintain longer complete remissions (CR) with aggressive post-remission therapies after induction treatment: allogeneic (allo), autologous (auto) stem cell transplantation (SCT), or intensive chemotherapy (ICC). The purpose of our study was to identify the most important randomized and controlled studies comparing these three therapeutic options, in order to draw conclusions and possible suggestions for post-remission therapy of AML, according to the evidence based medicine (EBM) rules. We performed an exhaustive analysis of the literature, searching either in electronic databases or among the references of the identified articles (hand searching). We searched the MEDLINE computer database for reports from 1985 through January 2005 and selected for analysis the clinical trials conducted over adults affected by newly diagnosed AML aged less than 65 years. The study design had to satisfy strict methodological criteria and must consider global mortality and/or disease free survival as primary outcomes. Overall we found 7750 papers; by using the limits “clinical trial” as publication type, “all adults 19+ years”, we were able to select 344 papers. Among these, a further selection was made, based on two main clinical queries: 1) is auto-SCT superior to ICC/no other therapy in improving DFS and/or OS in adult AML patients in first CR? 2) is allo-SCT superior to auto-SCT/other therapeutic options in improving DFS and/or OS in adult AML patients in first CR? Concerning the first query, a possible advantage of auto-SCT over ICC was not clearly supported by data from clinical trials; there is no evidence that auto-SCT is superior in terms of OS to chemotherapy. Nevertheless, the reported TRM has been significantly reduced within the past years. Thus, the percentage of patients suitable for auto-SCT in CR has increased. Moreover, the scarce data concerning the comparison between auto-SCT and chemotherapy in different subsets of patients are unable to suggest a differentiated approach in patients with high-risk, standard-risk or low-risk AML. Data from the literature show that patients with unfavorable risk disease are more often addressed to allo-SCT and patients with low-risk disease receive more often intensive consolidation chemotherapy. Concerning the second query, interpretation of data from the main prospective studies about the role of allo-SCT in previously untreated AML is not easy. The first problem is the lack of real randomized clinical trials; in fact, according to the reported studies, AML patients generally receive allo-SCT on the basis of donor availability (the so called “genetic randomization”). The second problem is the frequent absence of intention to treat analysis. Despite methodological limitations, it was possible to compare allo-SCT with auto-SCT on a donor versus no-donor analysis and within risk groups. No overall benefit of allo-grafting on survival was demonstrated by any trial. In conclusion, the EBM approach highlighted the limitations observed in the published studies concerning consolidation therapy in AML; some suggestions, emerging from non-randomized, as well as randomized studies, are adequate, but not conclusive. This point, coupled with the intrinsic complexity to study AML biological heterogeneity, is probably a major obstacle to draw conclusive evidences for consolidation therapy in AML. These observations should plan to address new randomized studies on AML therapy; however, due to the emergence of genetic subgroups and new drugs targeting specific abnormalities, these trials should probably be designed directly focusing on the single entities. In this way, the cure of AML could eventually become the cure of each specific AML subset with its peculiar biological, molecular and prognostic features.

CCAAT/Enhancer Binding Protein α (C/EBPα) and C/EBPα Myeloid Oncoproteins Induce Bcl-2 via Interaction of Their Basic Regions with Nuclear Factor-κB p50

The CEBPA gene is mutated in 10% of acute myeloid leukemia (AML) cases. We find that CEBPA and Bcl-2 RNA levels correlate highly in low-risk human AMLs, suggesting that inhibition of apoptosis via induction of bcl-2 by CCAAT/enhancer binding protein alpha (C/EBPalpha) or its mutant variants contributes to transformation. C/EBPalphap30, lacking a NH2-terminal transactivation domain, or C/EBPalphaLZ, carrying in-frame mutations in the leucine zipper that prevent DNA binding, induced bcl-2 in hematopoietic cell lines, and C/EBPalpha induced bcl-2 in normal murine myeloid progenitors and in the splenocytes of H2K-C/EBPalpha-Emu transgenic mice. C/EBPalpha protected Ba/F3 cells from apoptosis on interleukin-3 withdrawal but not if bcl-2 was knocked down. Remarkably, C/EBPalphaLZ oncoproteins activated the bcl-2 P2 promoter despite lack of DNA binding, and C/EBPalphap30 also activated the promoter. C/EBPalpha and the C/EBPalpha oncoproteins cooperated with nuclear factor-kappaB (NF-kappaB) p50, but not p65, to induce bcl-2 transcription. Endogenous C/EBPalpha preferentially coimmunoprecipitated with p50 versus p65 in myeloid cell extracts. Mutation of residues 297 to 302 in the C/EBPalpha basic region prevented induction of endogenous bcl-2 or the bcl-2 promoter and interaction with p50 but not p65. These findings suggest that C/EBPalpha or its mutant variants tether to a subset of NF-kappaB target genes, including Bcl-2, via p50 to facilitate gene activation and offer an explanation for preferential in-frame rather than out-of-frame mutation of the leucine zipper with sparing of the basic region in C/EBPalphaLZ oncoproteins. Targeting interaction between C/EBPalpha basic region and NF-kappaB p50 may contribute to the therapy of AML and other malignancies expressing C/EBPs.