Survival In Acute Myelogenous Leukemia Research Articles

Platelet Factor 4 Binds to Low-Density Lipoprotein Receptor to Block Leukemic Stem Cell Expansion and Recurrence

Healthy hematopoietic stem cells (HSCs) reside in highly specialized microenvironments within the bone marrow, commonly referred to as niches. HSC activity is tightly regulated by various cellular and molecular niche constituents that ensure healthy hematopoiesis. However, through the accumulation of mutations, hematopoietic stem and progenitor cells can give rise to leukemia-initiating cells or leukemic stem cells (LSCs), which play a vital role in the onset, progression, and treatment outcome of acute myelogenous leukemia (AML). In AML, the expansion of the leukemic clone is associated with impaired healthy hematopoiesis, resulting in severe anemia, thrombocytopenia, and immunodeficiency, which can lead to severe morbidity. Current therapeutic options mainly eliminate the bulk of leukemic cells but do not efficiently target LSCs, leading to the high rates of relapse seen in AML patients. Recent studies suggest that LSCs hijack and alter the healthy bone marrow niche to better support their maintenance and proliferation. Understanding how LSCs interact with the bone marrow microenvironment is crucial for eradicating LSCs and preventing AML relapse. Our previous work showed that platelet factor 4 (PF4), a chemokine stored in platelet alpha-granules and secreted by bone marrow megakaryocytes, can induce quiescence in healthy myeloid-biased HSCs ( Nature Medicine 2014; Developmental Cell 2018). Here, we investigate the regulation of malignant LSCs by PF4 using mouse and human AML models. In an aggressive mouse AML model, MLL-AF9, our results show that recombinant PF4 blocks the proliferation of phenotypic LSCs (Lineage − IL7Rα − Sca1 − MLL-AF9-GFP + c-Kit high CD34 + FcγRII/III high) in vitro (70% reduction; P=0.0279). Strikingly, cell cycle analyses revealed that in vivo, both LSCs and bulk AML proliferation are significantly inhibited 24 hours post-PF4 (80 mg/kg) injection, resulting in a significantly lower leukemic burden. By contrast, Pf4 -/- mice exhibited rapid AML disease progression via increased LSC proliferation. Furthermore, using a genetic mouse model ( Pf4-Cre; iDTR) where PF4-secreting megakaryocyte cells can be depleted in vivo in leukemic mice, our results revealed that megakaryocyte depletion led to poor AML survival due to accelerated disease progression (Log-rank P<0.0017). These results demonstrate that megakaryocyte-derived PF4 can directly regulate the proliferation of leukemia cells. Interestingly, our results indicate that AML drives striking alterations in bone marrow megakaryocytes, including a lower frequency, reduced cell maturation, and reduced secretion of PF4 (~80% reduction, P<0.0001) compared to healthy controls. Accordingly, PF4 levels are reduced in the serum of myelodysplastic syndrome patients where hyperproliferative malignant cells are found alongside dysplastic megakaryocytes. To assess whether recombinant PF4 can alter the course of AML relapse in a preclinical experimental setting, we treated moribund leukemic mice with the chemotherapeutic drug Cytarabine followed by 3 daily I.V. injections of PF4 (80 mg/kg) or saline. Strikingly, this short treatment with PF4 preferentially reduced the frequency of LSCs in vivo during the relapse phase of AML (75% reduction; P=0.05). Furthermore, mice transplanted with MLL-AF9 AML cells that were pre-treated with Cytarabine and PF4 in vitro had prolonged overall survival (Log-rank P<0.0132) compared to Cytarabine alone. Importantly, two of six mice had no detectable AML up to 150 days post-transplantation. Finally, single-cell RNA sequencing experiments revealed that PF4 signals through Low-Density Lipoprotein Receptor (LDLR) on LSCs, whose expression is significantly upregulated upon Cytarabine treatment, during the relapse phase. Functional studies with fluorescently labeled low-density lipoprotein (LDL) confirmed that PF4 limits LSC uptake of LDL via LDLR to block LSC proliferation ( P=0.0044), suggesting an important role for PF4 in AML metabolism. Altogether, our studies reveal an unknown function for PF4 in AML and highlight PF4's potential as an effective adjuvant therapy in preventing AML relapse by inhibiting the recurrence of chemotherapeutic-resistant LSCs.

Center Effects on Outcomes in the Treatment of Acute Myelogenous Leukemia (AML): A Multilevel, Community-Based, Case-Controlled Study

Background As with other complex therapies, treatment of AML varies among centers (ctrs) due to differences in patients (pts), infrastructure and care delivery models. Variation in ctrs practices, experience and resources may influence pt outcomes. Few studies have examined the association of ctr characteristics and survival in AML. Previous research offers conflicting results regarding outcomes of AML pts treated in National Cancer Institute Comprehensive Cancer Centers (NCICCC) versus community settings; neither study investigated ctr-level differences other than volume. We sought to compare AML outcomes in any of the HCA Healthcare (HCA) network of 131 community hospitals from 2011-18 with those reported in the Surveillance, Epidemiology, and End Results (SEER) database. We then examined pt, disease and center-related characteristics influencing outcomes in HCA hospitals. Methods We identified pts with AML (excluding APL) > 18 yrs treated between 10/31/11 and 10/31/18 in an HCA hospital (N = 4,882) and obtained pt level data from electronic medical records. A comparative population treated was developed from the most recent SEER database (2011-15; N = 19,349). We used coarsened exact matching to control for as many potential biases as possible. We compared mortality at 30, 90 and 120-days and overall survival curves between HCA and SEER . A Cox regression model was used to investigate differences in hazard rates among HCA facilities while simultaneously assessing the impact of patient characteristics and facility characteristics. Of the HCA patients, 1339 were treated in 6 hospitals that meet defined metrics of infrastructure, staffing, processes and volume as part of certification to participate in the Sarah Cannon Blood Cancer Network (SCBCN). Results Matching for age, gender and race, HCA pts were found to have significantly lower mortality than SEER at 30, 90 and 120 days (p<.001) as well as significantly better survival (p<0.001; fig.1). We next investigated how pt and facility characteristics interact to predict outcomes for HCA patients (table 1). Elevated White Count at diagnosis (HR=1.3), Charlson index (HR=1.1), older age (HR= 1.04), and receiving treatment at a hospital with larger bed count (HR=1.26) were associated with significantly worse survival. Commission on Cancer (COC) accreditation status, Socio-economic status (SES), distance to facility, and gender did not significantly impact risk. Being treated in the SCBCN (HR=0.68) and African American race (HR= 0.66) were associated with improved survival Conclusions Previous research utilizing registry data demonstrated better survival for pts with AML treated in higher volume centers but provides conflicting information about survival for pts treated in a NCICCC versus a community setting. Neither study examined center characteristics beyond NCI designation. This report examines a large pt cohort treated in community hospitals across the US. Pts treated in these hospitals had significantly better survival than a matched cohort from the SEER database. We validate the importance of age, acuity and Charlson index as adverse factors. Analysis of facility characteristics demonstrated that qualification as a member of SCBCN was associated with improved survival underscoring the importance of infrastructure, quality systems and volume in achieving improved outcomes. Disclosures Lemaistre: HCA: Employment. Chao:HCA: Employment. Cruz:1. Daiichi Sankyo advisory board: Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Speakers Bureau. Eghtedar:Verastem Oncology: Consultancy; Novartis: Consultancy, Honoraria, Speakers Bureau; Jazz: Consultancy, Honoraria, Speakers Bureau; Celgene: Honoraria, Speakers Bureau; Takeda: Honoraria, Speakers Bureau. Holder:Sarah Cannon: Employment. Malik:Kite Pharma: Honoraria. Rotta:Kadmon Corporation, LLC: Consultancy; Jazz: Speakers Bureau.

Hypomethylating Agent Maintenance Therapy after Allogeneic Stem Cell Transplant Improves Transplant Outcome in High Risk Acute Myelogenous Leukemia

Background: Allogeneic hematopoietic stem cell transplant (HSCT) is the only potential curative modality for high risk acute myelogenous leukemia (AML). However, relapse disease remains to be the main reason of failure of allogeneic HSCT. Salvage therapy for relapse AML after allogeneic HSCT is limited and rarely successful. Prognosis is poor with a 2-year survival rate of less than 20%. As majority of relapses occur within first 6 months after transplant, effective preventive intervention given early post allogeneic HSCT may be crucial. An ideal drug for pharmacologic maintenance is difficult to achieve as it should have activity against the disease without excessive myelosuppression or eradication of donor cells, and has minimal or low risk of exacerbation of graft-versus-host disease or additional toxicity. Azacitidine and decitabine are hypomethylating agents (HMAs), which work epigenetically to modulate various genes, including tumor suppressor genes. They have been shown to have benefits in improvement of event free survival and overall survival in relapse AML. Similar benefits have also been reported when low dose azacitadine was given after allogeneic stem cell transplant as a maintenance therapy. Method: This is a single institutional study carried out at the Bone Marrow Transplant Program at the University of Oklahoma Health Science Center. It was started as a case control study in June 2014 when post-transplant azacitadine protocol was initiated, and continues on as a prospective study. Subjects over 18 years old with high risk AML based on cytogenetic and molecular mutation undergoing allogeneic HSCT were enrolled from September 2013 to July 2018. The study is to compare outcome in patients received post-transplant low dose azacitidine at 32mg/m2 on days 1-5 every 28 days for 4 cycles initiating between 6-8 weeks post-transplant versus post-transplant observation. Multivariable cox proportional hazards model was derived to adjust for covariates that differ between the two treatment arms and was used to analyze time to relapse and overall survival in both arms; then our results were graphed using Kaplan Meier Plot. Results: This study included 49 patients undergoing allogeneic HSCT for high risk AML. They were divided into 2 groups with 31 patients received post-transplant azacitidine, and 18 patients did not (prior to initiation of post-transplant azacitadine protocol, control). Our Analysis concluded a greater proportion of deaths among the control group (88.89%) compared to the azacitidine group (25.81%). Majority of deaths in the control group was due to relapse (12 of 16 deaths). Relapse rate was higher in the control group (66.67%) as compared to azacitidine group (25.81%) with statistically significant improvement in time to relapse in the azacitidine group (not reach (NR)) versus 4.1 months in the control arm (log-rank p-value <0.0001) which was described in Figure (1). Median Overall survival was 7.6 months in control arm versus 27.4 months in the 8 patients who relapsed in azacitidine arm (log-rank p-value<0.0001). (Figure 2) Among the 29 subjects from both arms who were relapse-free, overall survival differed between the two treatment groups (log-rank p-value 0.003). Median survival time among those in the control group was 9.8 months. For the azacitidine arm, only 2 events occurred among the 23 relapse-free subjects while the remaining 21 subjects were censored (Figure 3). Among other transplant-related factors, disease status was not differed among the two groups (p=0.411), but conditioning regimen was (p=0.019) with a greater proportion of reduced intensity conditioning (RIC) in the control group (55.56%) than azacitadine group (22.58) (Table 1). After adjusting for conditioning regimen, hazard of relapse was 5.26 (1.99,13.93) times greater (p value<0.001) and death was 5.41 (1.99,13.93) times greater (p value<0.001) in the control group than azacitadine group. In our analysis, cause of death was not statistically significantly different among the two arms (p-value 0.325). Use of azacitidine post-HSCT did not increase the risk of GVHD or infections (table 2). Implications: Low dose azacitidine maintenance therapy after allogeneic stem cell transplant in high risk acute myelogenous leukemia decreases relapse rate, time to relapse and improved overall survival without increasing adverse events and no increased risk of graft-versus-host disease or infections. Disclosures No relevant conflicts of interest to declare.

The Impact of Cytogenetics on the Outcome of Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Relapsed/Refractory Acute Myeloid Leukemia: A Survey from the Acute Leukemia Working Party (ALWP) of EBMT

Abstract Introduction: Diagnostic karyotype is one of the most important determinants of initial response to treatment, remission duration and overall survival in Acute Myelogenous Leukemia (AML). Moreover, risk stratification of AML based on cytogenetic abnormalities is a key parameter for the success rate and outcome of allogeneic stem cell transplantation (allo-SCT) in AML. However, while the prognostic significance of chromosomal abnormalities is well established during frontline therapy, its influence at time of salvage therapy in Primary Refractory (Ref) and Relapsed (Rel) AML and the role of allo-SCT in this subset, remains uncertain. Patients and methods: This was a survey from the EBMT registry which included adult AML patients undergoing allo-SCT for Ref/Rel AML from HLA-matched related or 9/10 - 10/10 unrelated donor (UD) between 2000 and 2017. Patients were stratified according to cytogenetic risk as defined by Grimwade et al. (Blood 2010). Primary endpoint was Leukemia-Free Survival (LFS). Secondary endpoints were relapse cumulative incidence (RI), non-relapse mortality (NRM), overall survival (OS), acute and chronic GVHD and GVHD-relapse-free Survival (GRFS). Results: 2089 patients with Ref AML (n=972) and Rel AML (n=1117) were analyzed: 154 patients had a favorable risk, 1283 were in intermediate risk and 652 had an adverse cytogenetic risk. Median follow-up was 49 months. Patients and transplant characteristics are summarized in table 1. Patients in the favorable risk group were younger and transplanted more frequently in first or second relapse. Patients in the adverse risk group received more frequently transplants from 9/10 UD. FLT3-ITD mutation was present in 18%, 43% and 16% of the favorable, intermediate and adverse risk groups, respectively (p<10-3). The 3 groups were not significantly different in terms of Karnosfky score, patient and CMV serology status and conditioning intensity (myeloablative or reduced). Outcome correlated with cytogenetic category, with a percentage of complete remission within 100 days after transplant of 79%, 69% and 61% (p<10-3), RI at 2 years were 42%, 51% and 61% (p<10-5), LFS and OS rates were 34%, 27%, 18% and 41%, 33%, 22% in favorable, intermediate and adverse risk group (p<10-5 for both LFS and OS), respectively. Non-relapse mortality, on the contrary, did not differ among the three groups (24%, 21% and 21%, respectively; p=NS). We performed a multivariate analysis adjusting for all factors differing between risk groups and factors known as influencing outcome of AML patients after allograft. Compared to the favorable risk group, intermediate risk group was associated with a higher RI (HR=1.58; 95% CI: 1.17-2.14; p=0.003), lower LFS (HR=1.39; 95% CI: 1.09-1.77; p=0.008), lower OS (HR=1;47; 95% CI: 1.14-1.90; p=0.003) and lower GRFS (HR=1;29; 95% CI: 1.03-1.61; p=0.03). The adverse risk group was associated with a higher RI (HR=2.27; 95% CI: 1.65-3.10; p<10-5), lower LFS (HR=1.86; 95% CI: 1.44-2.40; p<10-5), lower OS (HR=1.89; 95% CI: 1.44-2.47; p<10-5) and lower GRFS (HR=1.62; 95% CI: 1.28-2.06; p<10-4; Figure1). In a subgroup analysis of patients in intermediate or adverse risk groups with available information on FLT3-ITD status, adverse cytogenetics remained an important prognostic factor for RI (HR=1.55; 95% CI: 1.22-1.97; p=0.0004), LFS (HR=1.37; 95% CI: 1.12-1.68; p=0.002), OS (HR=1.38; 95% CI: 1.11-1.70; p=0.003) and GRFS (HR=1.31; 95% CI: 1.08-1.59; p=0.006) compared to the intermediate risk group. Other poor prognostic factors in this population were presence of FLT3-ITD mutation, Rel vs Ref status at transplant, Karnofsky score <80%, use of bone marrow as stem cell source and patient CMV serology positivity. In vivo T cell depletion was associated with a lower risk of acute and chronic GVHD and a better GRFS. Conclusion: In Rel and Ref AML karyotype remains an important prognostic factor for those patients undergoing allo-SCT in active disease phase, allowing to separate patients into different risk groups. Moreover, FLT3-ITD mutation remains a negative prognostic factor in this population. Disclosures Beelen: Medac: Consultancy, Other: Travel Support. Tischer:Jazz Pharmaceuticals: Other: Jazz Advisory Board. Finke:Novartis: Consultancy, Honoraria, Other: travel grants, Research Funding; Medac: Consultancy, Honoraria, Other: travel grants, Research Funding; Neovii: Consultancy, Honoraria, Other: travel grants, Research Funding; Riemser: Consultancy, Honoraria, Research Funding. Ganser:Novartis: Membership on an entity's Board of Directors or advisory committees. Mohty:MaaT Pharma: Consultancy, Honoraria.

Addition of Gemtuzumab Ozogamicin (GO) to Fludarabine, Cytarabine and G-CSF (FLAG) Based Induction Regimen Results in Better Early Molecular Response and Relapse Free Survival Compared to Idarubicin (FLAG-Ida) in Newly Diagnosed Core Binding Factor Leukemia

Addition of Gemtuzumab Ozogamicin (GO) to Fludarabine, Cytarabine and G-CSF (FLAG) Based Induction Regimen Results in Better Early Molecular Response and Relapse Free Survival Compared to Idarubicin (FLAG-Ida) in Newly Diagnosed Core Binding Factor Leukemia

Molecular and Immunophenotypic Characteristics of Adult Acute Leukemias of Ambiguous Lineage

Acute undifferentiated leukemia (AUL) and mixed phenotype acute leukemia (MPAL) are acute leukemias of ambiguous lineage representing less than 5% of all adult leukemias. Ontogenetically, they are thought to be caused by precursor lesions in early pluripotent hematopoietic progenitor cells having the ability to differentiate into both lymphoid and myeloid lineages. In contrast, common lymphoid and myeloid leukemias are likely derived from precursor lesions in committed progenitor cells. The molecular characteristics of the cell of origin of these leukemias have not been fully characterized.Given the ambiguous classification of these disorders, we used NGS to evaluate the molecular profiles of this unique subset of leukemias. Our panel tested for the 60 most commonly mutated genes in myeloid malignancies (MM), which can be used to further elucidate driver mutations that play a role in the pathogenesis of this unique entity. Molecular data was available for 18 of 35 patients (pts) (51%), of whom 8 were T/myeloid, 7 were B/myeloid, and 3 were AUL. 14 pts out of the 18 had samples at the time of initial diagnosis, 3 AUL cases harbored mutations commonly seen in MM, including one patient with DNMT3A and a germ line JAK3 mutation, another with U2AF1 and PHF6 mutations, and one pt with SF3B1 and MECOM mutations. Of the 5 B/myeloid cases, 4 had only one mutation detected by the sequencing panel, including TET2, PTPN11, KDM6A, and PHF6, and one had no mutations, but did have complex cytogenetics. Of interest, we identified four patients with T/myeloid MPAL that harbored a FLT3-ITD mutation. Notably, one of these cases had additional DNMT3A and TET2 mutations while another case had a WT1 mutation. We assert that the mutational data for MPAL supports that T-myeloid MPAL encompasses a borderland between early T precursor (ETP)-ALL/AML in addition to more typical cases of T-ALL/AML given its similar immunophenotype to ETP ALL (CD117, CD13 and CD33 positive). The overlap between these two entities is illustrated in the figure below. With this immunophenotyping and molecular profiling we propose a new provisional entity, ETP-myeloid MPAL in addition to already existing ETP ALL.Of 1250 pts with acute leukemia diagnosed from 1997-2016 at Cleveland Clinic, 35 had immunophenotypic characteristics of ambiguous leukemia based on WHO criteria. The median age at diagnosis was 50 years, and 22 (63%) were male. There were 31 MPAL (16 T/myeloid, 15 B/myeloid) and 4 AUL cases. Among the 31 MPAL patients, 2 were mixed lineage chimera (subclones), and 29 had true biphenotypic features. 48% of the cohort had normal cytogenetics at diagnosis, 23% had other cytogenetic abnormalities, 14% had complex karyotype, 9% had MLL gene rearrangement, and 6% had t(9;22). 62% of pts were treated with acute lymphoblastic leukemia (ALL) directed induction chemotherapy (IC), while 38% were treated with acute myelogenous leukemia (AML) directed IC. Rates of complete remission (CR) were significantly higher in pats treated with ALL-IC regimen (82%) versus AML-IC regimen (23%) (p=.003). In our study, two cases with the recurrent lymphoid mutations WT1 and KDM6A, that achieved CR with upfront ALL-IC, while one case with FLT3-ITD, DNMT3A, and TET2 mutations achieved CR with AML-IC treatment. Pts <40 yrs of age had significantly better median OS (41 months) than patients over 40 yrs old (16 months) (p=0.03). MPAL pts with normal cytogenetics had worse median OS (16 months) compared to any other cytogenetic group (25 months) (p=.05).In conclusion, clinical evaluations of ambiguous leukemias demonstrate that those with normal karyotype have the worst outcome of all pts diagnosed with MPAL. This can be partly explained by mutations that are detected at the time of diagnosis such as FLT3-ITD and DNMT3A, which have been associated with poor survival in AML with normal karyotype. Identification of actionable targets like FLT3-ITD can improve clinical outcomes for this subset of patients prior to BMT or for those ineligible for BMT. The existence of a unique subset of pts with immunophenotypic overlap between ETP-ALL/AML, that were classified in routine practice as T/myeloid leukemia, are important to recognize due to their unique actionable phenotype. Molecular profiling of these cases identified gene mutations more akin to MM. We propose that sequencing may play an important role in optimizing the therapeutic approach for patients with ambiguous lineage leukemia. [Display omitted] DisclosuresCarraway:Novartis: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Incyte: Membership on an entity's Board of Directors or advisory committees; Baxalta: Speakers Bureau; Celgene: Research Funding, Speakers Bureau.

Ribosomal Protein L22 Loss Predisposes Stem Cells to Transformation By Altering Metabolism

While mutations in ribosomal proteins (RP) have long been associated with increased cancer risk, the molecular basis for this association remains unclear. The prevailing view is that mutations in RP increase cancer risk either by impairing the biogenesis or function of the ribosome. Here, we report that loss of the RP, Rpl22, is frequently observed in human myelodysplastic syndrome (MDS) and is associated with reduced survival in acute myelogenous leukemia (AML). The link between Rpl22 loss and aggressiveness of myeloid disease is causal, since it is replicated in mice lacking Rpl22. Importantly, the development of an MDS-like syndrome in Rpl22-deficient mice and the accelerated development of myeloid leukemia are not caused by reduced protein synthesis in hematopoietic stem cells (HSC). Instead, whole transcriptome analysis of HSC reveals that Rpl22 loss alters the expression of genes controlling cell metabolism and results in an increase in fatty acid oxidation. Moreover, the increased fatty acid oxidation is required for the increased self-renewal and reduced differentiation displayed by Rpl22-deficient HSC, as well as the survival of Rpl22-deficient myeloid leukemia cells. Together, these findings indicate that RP are capable of suppressing transformation potential in ways that do not involve effects on global protein synthesis. Indeed, Rpl22 suppresses transformation by suppressing lipid oxidation, suggesting that MDS and AML patients with reduced Rpl22 expression might benefit from pharmacologic interventions targeting lipid oxidation. DisclosuresNo relevant conflicts of interest to declare.

Redirecting Specificity of T cells Using the Sleeping Beauty System to Express Chimeric Antigen Receptors by Mix-and-Matching of VL and VH Domains Targeting CD123+ Tumors.

Adoptive immunotherapy infusing T cells with engineered specificity for CD19 expressed on B- cell malignancies is generating enthusiasm to extend this approach to other hematological malignancies, such as acute myelogenous leukemia (AML). CD123, or interleukin 3 receptor alpha, is overexpressed on most AML and some lymphoid malignancies, such as acute lymphocytic leukemia (ALL), and has been an effective target for T cells expressing chimeric antigen receptors (CARs). The prototypical CAR encodes a VH and VL from one monoclonal antibody (mAb), coupled to a transmembrane domain and one or more cytoplasmic signaling domains. Previous studies showed that treatment of an experimental AML model with CD123-specific CAR T cells was therapeutic, but at the cost of impaired myelopoiesis, highlighting the need for systems to define the antigen threshold for CAR recognition. Here, we show that CARs can be engineered using VH and VL chains derived from different CD123-specific mAbs to generate a panel of CAR+ T cells. While all CARs exhibited specificity to CD123, one VH and VL combination had reduced lysis of normal hematopoietic stem cells. This CAR’s in vivo anti-tumor activity was similar whether signaling occurred via chimeric CD28 or CD137, prolonging survival in both AML and ALL models. Co-expression of inducible caspase 9 eliminated CAR+ T cells. These data help support the use of CD123-specific CARs for treatment of CD123+ hematologic malignancies.

High-Sensitivity Genomic Minimal Residual Disease Detection Reveals Multiclonal Hematopoiesis and Is Associated with Survival in Adult AML

▪Introduction: Minimal residual disease (MRD) measurement is emerging as a prognostic marker of relapse-free survival (RFS) and overall survival (OS) in acute myelogenous leukemia (AML). In order to improve the technical feasibility of MRD detection and to enable broad, ultra-sensitive mutational profiling of residual AML, we optimized a droplet-based digital PCR (ddPCR) approach capable of detecting mutated alleles in most recurrently mutated genes in AML in as few as 5 in 100,000 cells. We subsequently analyzed bone marrow specimens of AML patients in early complete remission (CR) and correlated MRD levels with outcome.Methods: Fifty-two consecutively enrolled patients with AML at a single center who had paired diagnostic and CR bone marrow specimens were studied. First, genomic DNA from FACS-purified leukemic cells of diagnostic samples underwent Sanger resequencing of NPM1, IDH1, IDH2, NRAS, KRAS, FLT3, TP53, DNMT3A, TET2, ASXL1, BCORL1, CEBPA, and RUNX1. For cases with <2 mutations identified, an additional 36 recurrently mutated genes in AML were sequenced using droplet-based library preparation and massively parallel sequencing. Second, allele-specific fluorescent oligonucleotide probes using minor groove-binding or locked nucleic acid chemistries were developed for each mutation and optimized for allele discrimination using quantitative PCR. ddPCR (RainDance Technologies) was then performed on replicate DNA samples extracted from Ficoll-enriched bone marrow aspirates obtained in CR (median time from induction: 36d) to determine variant allele frequency (VAF) for all mutations.Results: In CR bone marrow samples, we detected residual gene mutations in 88% of cases (46 of 52) using a detection threshold of 0.005% VAF. Notably, DNMT3A and TET2 mutations persisted at >1% VAF in 85% (11 of 13) (range 1.6-34.6%) and 50% (5 of 10) (range 2.3-15.1%) of cases, respectively, including in patients with subsequent durable remissions (>1000 days). Conversely, 94% (15 of 16) and 100% (5 of 5) of NPM1 and NRAS mutations, respectively, were reduced to <1% VAF, and 44% (7 of 16) of NPM1 mutations and 60% (3 of 5) of NRAS mutations were undetectable.In cases for which ≥2 mutations were measured (N=28), two distinct patterns of residual allele burden were identified. In 32% (9 of 28) of cases, the VAFs of all genes measured were concordant (<1 log difference in VAF), but importantly, in 68% (19 of 28) of cases one or more VAFs were discordant (≥1 log difference), indicative of separate residual clones. In discordant cases, DNMT3A was the most common mutated gene of highest VAF (10 of 19, 53%), while NPM1 was the most frequent gene mutation of lowest VAF (10 of 19, 53%).Kaplan-Meier analysis of all patients in first CR (N=48) was performed using a cutoff of 0.01% VAF to define MRDhigh (N=33) and MRDlow/neg (N=15) groups. Due to frequent high-level persistence, DNMT3A mutations were excluded from the analysis. In cases where ≥2 mutations were measured, the highest VAF was used to assign that case. MRD burden was associated with RFS (MRDhigh, median RFS 9.9 mo; MRDlow/neg, median RFS not reached; p <0.01) and OS (MRDhigh, median OS 17.8 mo; MRDlow/neg, median OS not reached; p <0.01). In the exploratory subset of patients who proceeded to allogeneic stem cell transplantation in first CR (N=13), all patients who were MRDlow/neg (N=5) remained in a long-term remission, while 75% of MRDhigh (6 of 8) patients relapsed (median RFS 14.8 mo; p =0.01).Conclusions: High sensitivity measurement of residual clonal hematopoiesis with digital PCR is feasible for the majority of recurrently mutated genes in AML. Most DNMT3A and some TET2 and IDH1 mutations persist at high levels in remission even in patients with subsequent durable clinical remissions, further refining the hierarchical acquisition model of gene mutations in AML and implying they are present in pre-leukemic or non-blast differentiated cell populations. Due to high MRD levels, mutations in DNMT3A and possibly TET2 and IDH1 may not be suitable for use in MRD-based prognostication. The majority of cases with multiple measured gene mutations demonstrate discordance in VAF suggesting the simultaneous persistence of chemosensitive, chemoresistant and pre-leukemic populations. Ongoing work aims at identifying which mutation-defined subclones are responsible for relapse. Finally, in this cohort mutation-based MRD measured at initial CR is associated with RFS and OS. DisclosuresMalek:Abbvie: Equity Ownership; Gilead Sciences: Equity Ownership; Janssen Pharmaceuticals: Research Funding.

Integrated Genomic Profiling, Therapy Response And Survival in Adult Acute Myelogenous Leukemia

Purpose: Recurrent gene mutations, chromosomal translocations, and acquired genomic copy number aberrations (aCNA) have been variously associated with acute myelogenous leukemia (AML) patient outcome. However, knowledge of the co-occurrence of such lesions and the relative influence of different types of genomic alterations on clinical outcomes in AML is still evolving. Experimental Design: We performed SNP 6.0 array-based genomic profiling of aCNA/copy neutral loss-of-heterozygosity (cnLOH) along with sequence analysis of 13 commonly mutated genes on purified leukemic blast DNA from 156 prospectively enrolled non-FAB-M3 AML patients across the clinical spectrum of de novo , secondary, and therapy-related AML. Results: TP53 and RUNX1 mutations are strongly associated with the presence of SNP-A–based aCNA/cnLOH, while FLT3 and NPM1 mutations are strongly associated with the absence of aCNA/cnLOH. The presence of mutations in RUNX1 , ASXL1 , and TP53 , elevated SNP-A–based genomic complexity, and specific recurrent aCNAs predicted failure to achieve a complete response to induction chemotherapy. The presence of ≥1 aCNA/cnLOH and higher thresholds predicted for poor long-term survival irrespective of TP53 status, and the presence of ≥1 aCNA/cnLOH added negative prognostic information to knowledge of mutations in TET2 , IDH1 , NPM1 , DNMT3A , and RUNX1 . Results of multivariate analyses support a dominant role for TP53 mutations and a role for elevated genomic complexity as predictors of short survival in AML. Conclusions: Integrated genomic profiling of a clinically relevant adult AML cohort identified genomic aberrations most associated with SNP-A–based genomic complexity, resistance to intensive induction therapies, and shortened overall survival. Identifying SNP-A–based lesions adds prognostic value to the status of several recurrently mutated genes. Clin Cancer Res; 1–12. ©2015 AACR.

EphB1 Suppression in Acute Myelogenous Leukemia: Regulating the DNA Damage Control System.

Loss of ephrin receptor (EphB1) expression may associate with aggressive cancer phenotypes; however, the mechanism of action remains unclear. To gain detailed insight into EphB1 function in acute myelogenous leukemia (AML), comprehensive analysis of EphB1 transcriptional regulation was conducted. In AML cells, EphB1 transcript was inversely correlated with EphB1 promoter methylation. The presence of EphB1 allowed EfnB1 ligand-mediated p53 DNA binding, leading to restoration of the DNA damage response (DDR) cascade by the activation of ATR, Chk1, p53, p21, p38, CDK1(tyr15), and Bax, and downregulation of HSP27 and Bcl2. Comparatively, reintroduction of EphB1 expression in EphB1-methylated AML cells enhanced the same cascade of ATR, Chk1, p21, and CDK1(tyr15), which consequently enforced programmed cell death. Interestingly, in pediatric AML samples, EphB1 peptide phosphorylation and mRNA expression were actively suppressed as compared with normal bone marrow, and a significant percentage of the primary AML specimens had EphB1 promoter hypermethylation. Finally, EphB1 repression associated with a poor overall survival in pediatric AML. Combined, the contribution of EphB1 to the DDR system reveals a tumor-suppressor function for EphB1 in pediatric AML. The tumor-suppressor function of EphB1 is clinically relevant across many malignancies, suggesting that EphB1 is an important regulator of common cancer cell transforming pathways.

Integrated genomic profiling, therapy response, and survival in adult acute myelogenous leukemia.

Recurrent gene mutations, chromosomal translocations, and acquired genomic copy number aberrations (aCNA) have been variously associated with acute myelogenous leukemia (AML) patient outcome. However, knowledge of the co-occurrence of such lesions and the relative influence of different types of genomic alterations on clinical outcomes in AML is still evolving. We performed SNP 6.0 array-based genomic profiling of aCNA/copy neutral loss-of-heterozygosity (cnLOH) along with sequence analysis of 13 commonly mutated genes on purified leukemic blast DNA from 156 prospectively enrolled non-FAB-M3 AML patients across the clinical spectrum of de novo, secondary, and therapy-related AML. TP53 and RUNX1 mutations are strongly associated with the presence of SNP-A-based aCNA/cnLOH, while FLT3 and NPM1 mutations are strongly associated with the absence of aCNA/cnLOH. The presence of mutations in RUNX1, ASXL1, and TP53, elevated SNP-A-based genomic complexity, and specific recurrent aCNAs predicted failure to achieve a complete response to induction chemotherapy. The presence of ≥1 aCNA/cnLOH and higher thresholds predicted for poor long-term survival irrespective of TP53 status, and the presence of ≥1 aCNA/cnLOH added negative prognostic information to knowledge of mutations in TET2, IDH1, NPM1, DNMT3A, and RUNX1. Results of multivariate analyses support a dominant role for TP53 mutations and a role for elevated genomic complexity as predictors of short survival in AML. Integrated genomic profiling of a clinically relevant adult AML cohort identified genomic aberrations most associated with SNP-A-based genomic complexity, resistance to intensive induction therapies, and shortened overall survival. Identifying SNP-A-based lesions adds prognostic value to the status of several recurrently mutated genes.

A cytosine methylation signature that predicts overall survival in acute myelogenous leukemia (AML)

A cytosine methylation signature that predicts overall survival in acute myelogenous leukemia (AML)

Activation Of Akt Enhances Ribosomal RNA Synthesis In AML Cells Through a Novel Isoform Of TIF-1A and Inhibition Of Filamin A Cleavage

PI3Kinase/Akt signaling is frequently activated in acute myelogenous leukemia (AML) and inhibitors of this pathway have shown some promise in both pre-clinical and early clinical studies. In particular, much attention has been focused on components of the mTOR complex as downstream effectors of Akt activation that promote cell proliferation and survival in AML and other malignancies. We have discovered a direct effect of activated and phosphorylated Akt in increasing ribosomal RNA (rRNA) synthesis in both leukemic cell lines and primary AML cells by a novel pathway that is independent of mTOR. We have defined TIF-90 as a splice variant of TIF-1A, a molecule that tethers RNA Polymerase I to the ribosomal DNA promoter and is required for rRNA synthesis. TIF-90 is localized in the nucleolus and directly co-locates with Pol I in imaging, pull down, and rDNA promoter occupancy studies. Activation and phosphorylation of Akt correlates with high levels of TIF-90 expression and increased TIF-90 occupancy of the rDNA promoter in primary AML cells, while overexpression of constitutively activated Akt (Akt-Myr) increases rRNA synthesis in a TIF-90-dependent fashion in cell lines. Activation of Akt increases the expression of TIF-90 by inhibiting its ubiquitination and proteasomal degradation by the p53 ubiquitin ligase, Mdm2. Furthermore, activated Akt directly inhibits the cleavage of the actin-binding protein, Filamin A, into a 90 kDa fragment that interacts with TIF-90 and prevents it from occupying the rDNA promoter. Expression of the 90 kDa Filamin A cleavage fragment alone is sufficient to inhibit rRNA synthesis by binding to TIF-90. Thus, inhibition of Filamin A cleavage by Akt is associated with increased rRNA synthesis. The Akt inhibitor AZD8055, but not the mTORC1 inhibitor Rapamycin, promotes the cleavage of filamin A, decreasing both TIF-90 occupancy of the rDNA promoter and rRNA synthesis. Examination of 21 primary AML samples reveals an inverse correlation between the phosphorylation of Akt and the cleavage of Filamin A; conversely, AZD8055 inhibits both Akt phosphorylation and rRNA synthesis in these samples while promoting the cleavage of Filamin A. These data demonstrate a novel pathway by which Akt directly enhances rRNA synthesis. This pathway is active in primary AML cells and in cell lines that have high levels of phosphorylated Akt. Inhibition of rRNA synthesis has been shown to result in nucleolar disruption, cell cycle arrest, and ultimately cell death. Our data support an mTOR-independent effect of Akt activation on cell proliferation that would require direct targeting of PI3Kinase or activated Akt to have a major therapeutic effect in AML. Disclosures:No relevant conflicts of interest to declare.

The pp90rsk-CREB Signaling Pathway Regulates Apoptosis In Acute Myelogenous Leukemia

CREB (cAMP Response-Element Binding Protein) is a nuclear transcription factor critical for hematopoietic cell proliferation, differentiation, and survival. We previously demonstrated that 60% of patients with Acute Myelogenous Leukemia (AML) overexpress CREB in leukemic blasts, and CREB overexpression in these patients was associated with an increased risk of relapse and decreased event-free survival. Previous studies have suggested that CREB may play an important role in the regulation of apoptosis in a wide variety of cancers. Specifically, CREB has been shown to up-regulate members the anti-apoptotic protein family such as Bcl-2, Bcl-XL and Mcl-1, leading to chemotherapy resistance in vitro. CREB-mediated resistance to apoptosis may underlie the increased rate of relapse and poor survival of AML patients with CREB overexpression. Thus, we hypothesized that targeted inhibition of CREB in AML cells would promote AML cell apoptosis. To test this hypothesis, we developed a small-molecule inhibitor of CREB function, XX-650-23. This molecule disrupts the interaction between CREB and its binding partner CBP (CREB-Binding Protein), which is required for full activation of CREB-mediated gene transcription. Treatment of primary AML patient bone marrow samples with XX-650-23 induced apoptosis and cell death at a dose of 2 uM. The degree of apoptosis varied with the expression level of CREB in primary AML cells tested. Higher CREB levels correlated with higher sensitivity to XX-650-23. In non-leukemic primary patient bone marrow samples, CREB levels were very low, and XX-650-23 did not induce apoptosis in these cells. AML cell lines (KG-1 and HL-60) also underwent apoptosis following CREB inhibition, in proportion to CREB expression level. CREB knockdown or overexpression in KG-1 cells decreased and increased susceptibility to apoptosis, respectively. Mechanistically, the onset of apoptosis in AML cells occurred simultaneously with down-regulation of Bcl-2, a validated CREB-regulated gene. Inhibition of Bcl-2 function using the specific Bcl-2 inhibitor ABT-737 (100 nM) induced apoptosis similar to XX-650-23, indicating that Bcl-2 inhibition alone is sufficient to cause apoptosis. Thus, targeted inhibition of CREB results in Bcl-2 downregulation and is sufficient to induce apoptosis in AML cells. Proteomic analysis using Mass Cytometry-Time of Flight (CyTOF) revealed that one compensatory cellular response to CREB inhibition is increased phosphorylation of CREB. This phosphorylation decreased in the presence of BI-D1870, a specific inhibitor of the pp90RSK kinase (RSK), but not by pharmacologic inhibition of the p38 or ERK kinases, using SB202190 or U0126, respectively. We therefore examined the role of pp90RSK in the regulation of apoptosis in AML cells. Pharmacologic inhibition of RSK independently lead to AML cell apoptosis (BI-D1870, IC50=3.3 uM), in part due to blockade of CREB phosphorylation. In summary, our data provide the first evidence that inhibition of CREB, or its chief activator RSK, is sufficient to induce apoptosis in AML cells. Current work focuses on defining CREB target genes mediating XX-650-23 response using chromatin-immunoprecipitation with massively parallel DNA sequencing (ChIP-Seq), and defining the RSK kinome in AML cells using 2-dimensional gel phosphoprotein profiling. These studies will more fully define the role of the RSK-CREB signaling axis in AML proliferation, survival, and apoptosis. Disclosures:No relevant conflicts of interest to declare.

BCL-2 inhibition with ABT-737 prolongs survival in an NRAS/BCL-2 mouse model of AML by targeting primitive LSK and progenitor cells

AbstractMyelodysplastic syndrome (MDS) transforms into an acute myelogenous leukemia (AML) with associated increased bone marrow (BM) blast infiltration. Using a transgenic mouse model, MRP8[NRASD12/hBCL-2], in which the NRAS:BCL-2 complex at the mitochondria induces MDS progressing to AML with dysplastic features, we studied the therapeutic potential of a BCL-2 homology domain 3 mimetic inhibitor, ABT-737. Treatment significantly extended lifespan, increased survival of lethally irradiated secondary recipients transplanted with cells from treated mice compared with cells from untreated mice, with a reduction of BM blasts, Lin-/Sca-1+/c-Kit+, and progenitor populations by increased apoptosis of infiltrating blasts of diseased mice assessed in vivo by technicium-labeled annexin V single photon emission computed tomography and ex vivo by annexin V/7-amino actinomycin D flow cytometry, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling, caspase 3 cleavage, and re-localization of the NRAS:BCL-2 complex from mitochondria to plasma membrane. Phosphoprotein analysis showed restoration of wild-type (WT) AKT or protein kinase B, extracellular signal-regulated kinase 1/2 and mitogen-activated protein kinase patterns in spleen cells after treatment, which showed reduced mitochondrial membrane potential. Exon specific gene expression profiling corroborates the reduction of leukemic cells, with an increase in expression of genes coding for stem cell development and maintenance, myeloid differentiation, and apoptosis. Myelodysplastic features persist underscoring targeting of BCL-2-mediated effects on MDS–AML transformation and survival of leukemic cells.

Myelodysplasia: New Approaches

The myelodysplastic syndromes (MDS) are a group of clonal hematopoietic disorders characterized by bone marrow failure and a risk of progression to acute myelogenous leukemia (AML). A precise diagnosis is critical, because there is overlap between the clinical and laboratory findings of MDS and other malignant and nonmalignant hematologic disorders. Several prognostic scoring systems (IPSS, WPSS, LR-PSS, and IPSS-R) assess a patient's risk of progression to AML and overall survival. Many patients are elderly, so age and comorbidities are an important consideration. Patients with lower-risk disease are treated with growth factors (erythropoietin stimulating agents and/or G-CSF) and immunomodulatory agents (antithymocyte globulin and/or lenalidomide). Patients with higher-risk disease have a higher risk of progression to AML and are treated with hypomethylating agents (azacitidine or decitabine) and allogeneic stem cell transplantation if appropriate. Recent laboratory studies have increased our understanding of the pathophysiology of this disease. Mutations in genes effecting ribosomes, splicing of RNA and epigenetics have been discovered. It is likely that these breakthroughs will lead to newer classes of targeted therapies against this disease.

Notch activation inhibits AML growth and survival: a potential therapeutic approach

Although aberrant Notch activation contributes to leukemogenesis in T cells, its role in acute myelogenous leukemia (AML) remains unclear. Here, we report that human AML samples have robust expression of Notch receptors; however, Notch receptor activation and expression of downstream Notch targets are remarkably low, suggesting that Notch is present but not constitutively activated in human AML. The functional role of these Notch receptors in AML is not known. Induced activation through any of the Notch receptors (Notch1-4), or through the Notch target Hairy/Enhancer of Split 1 (HES1), consistently leads to AML growth arrest and caspase-dependent apoptosis, which are associated with B cell lymphoma 2 (BCL2) loss and enhanced p53/p21 expression. These effects were dependent on the HES1 repressor domain and were rescued through reexpression of BCL2. Importantly, activated Notch1, Notch2, and HES1 all led to inhibited AML growth in vivo, and Notch inhibition via dnMAML enhanced proliferation in vivo, thus revealing the physiological inhibition of AML growth in vivo in response to Notch signaling. As a novel therapeutic approach, we used a Notch agonist peptide that led to significant apoptosis in AML patient samples. In conclusion, we report consistent Notch-mediated growth arrest and apoptosis in human AML, and propose the development of Notch agonists as a potential therapeutic approach in AML.

ASXL1 mutations in GATA2-Deficiency Correlate with Leukemic Transformation

AbstractAbstract 405 Background:Recently, monoallelic mutations in the zinc-finger transcription factor GATA2 have been shown to be responsible for GATA2-deficiency, a syndrome characterized by opportunistic infections, frequently atypical mycobacterial infections or MAC, and a hypocellular myelodysplastic syndrome (MDS) that transforms into acute myelogenous leukemia (AML). GATA2-deficiency was previously known by several other names: MonoMAC (Monocytopenia and Atypical Mycobacterial Infection), DCML (Dendritic Cell Monocyte, Lymphoid Deficiency), Familial MDS/AML, or Emberger syndrome (lymphedema with monosomy 7). Heterogeneous genetic defects in GATA2 result in haploinsufficiency in both spontaneous and familial forms of the disease. Predicting the transformation from MDS to AML in GATA2-deficiency has clinical implications for both prognosis and the timing of hematopoietic stem cell transplantation. ASXL1, a gene related to the Drosophilia additional sex combs gene, encodes a chromatin binding/transcription repressor protein that is frequently mutated in MDS/AML. Mutations in ASXL1 are associated with reduced time to progression to AML and poor overall survival, independent of IPSS score. Methods:We sequenced the critical region of the ASXL1 gene in 20 patients with GATA2- deficiency to determine the frequency of ASXL1 mutations, and to correlate the presence of ASXL1 mutations with hematopoietic transformation. Since the ASXL1 mutations described in hematopoietic malignancies are located within the coding sequence of the two 3Õ-terminal exons (COSMIC: Catalogue of Somatic Mutations in Cancer), this ∼4.3kb region of ASLX1 was amplified by PCR and sequenced using five overlapping primer sets with substrate DNA isolated from mononuclear cell and granulocyte cell preparations from peripheral blood or bone marrow aspirates, or from extracts prepared from unfixed, unstained bone marrow aspirates. Mutations were confirmed with at least two independent PCR reactions with two unique primer sets. Results:Somatic ASXL1 mutations were detected in 8 of 20 patients with GATA2 mutations, 19/20 of whom had MDS. Five of these ASXL1 mutations have been previously associated with MDS/AML, including four independent cases of the most frequently described ASXL1 mutation (G646fs*12insG). The other four mutations were found once each; two of these were previously unreported (G652S(G>A) and L817fs*1delT). The patient cohort included two sisters with the same germline GATA2R398W mutation, but different somatic ASXL1 mutations (G464fs*12insG and R693X(C>T)). ASXL1 mutations were found in 4/5 GATA2- deficiency patients whose MDS had transformed into chronic myelomonocytic leukemia (CMML). Overall survival was lower for GATA2-deficiency patients with ASXL1 mutation (50% survival) compared to patients without ASXL1 mutation (83% survival), and was independent of IPSS score. [Display omitted] Conclusions:ASXL1 is frequently mutated in patients with GATA2-deficiency with at least 40% of patients having a mutation in ASXL1 compared to a 10–15% mutation rate reported for all MDS/AML patients. ASXL1 mutation correlates with the development of CMML and with poor overall survival, as reported previously for MDS/AML patients. There was no correlation between the presence and type of ASXL1 mutation and the specific GATA2 mutation: the eight different ASXL1 mutation events were found in six different GATA2 mutant backgrounds. These results are directly relevant to the prognosis and the timing of hematopoietic stem cell transplantation for GATA2-deficiency. Disclosures:No relevant conflicts of interest to declare.

Colony-stimulating factors for prevention and treatment of infectious complications in patients with acute myelogenous leukemia

Acute myelogenous leukemia (AML) is a fatal bone marrow cancer. Colony-stimulating factors (CSFs) are frequently administered during and after chemotherapy to reduce complications. However, their safety with regard to disease-related outcomes and survival in AML is unclear.Therefore, we performed a systematic review and meta-analysis to evaluate the impact of CSFs on patient outcomes, including survival. To assess the safety/efficacy of CSFs with regard to disease-related outcomes and survival in patients with AML. We conducted a comprehensive search strategy. We identified relevant randomized clinical trials by searching the Cochrane Central Register of Controlled Trials (The Cochrane Library 2010, Issue 7), MEDLINE (January 1966 to July 2010), LILACS (up to December 2009), databases of ongoing trials and relevant conference proceedings. Randomized controlled trials that compared the addition of CSFs during and following chemotherapy to chemotherapy alone in patients with AML. We excluded trials evaluating the role of CSFs administered for the purpose of stem cell collection and/or priming (e.g. before and/or only for the duration of chemotherapy). Two review authors appraised the quality of trials and extracted data. For each trial, we expressed results as relative risk (RR) with 95% confidence intervals (CI) for dichotomous data. We analyzed time-to-event outcomes as hazard ratios (HRs). The search yielded 19 trials including 5256 patients. The addition of CSFs to chemotherapy yielded no difference in all-cause mortality at 30 days and at the end of follow up (RR 0.97; 95% CI 0.80 to 1.18 andRR 1.01; 95% CI 0.98 to 1.05, respectively) or in overall survival (HR 1.00; 95% 0.93 to 1.08). There was no difference in complete remission rates (RR 1.03; 95% CI 0.99 to 1.07), relapse rates (RR 0.97; 95% CI 0.89 to 1.05) and disease-free survival (HR 1.00; 95% CI 0.90 to 1.13). CSFs did not decrease the occurrence of bacteremias (RR 0.96; 95% CI 0.82 to 1.12), nor the occurrence of invasive fungal infections (RR 1.40; 95% CI 0.90 to 2.19). CSFs marginally increased adverse events requiring discontinuation of CSFs as compared to the control arm (RR 1.33; 95% CI 1.00 to 1.56). In summary, colony-stimulating factors should not be given routinely to acute myelogenous leukemia patients post-chemotherapy since they do not affect overall survival or infectious parameters including the rate of bacteremias and invasive fungal infections.