French-American-British M4 Research Articles

RNA expression-based risk stratification of de novo acute myeloid leukemia.

e18503 Background: Prognostication of acute myeloid leukemia (AML) at initial diagnosis relies on the identification of certain underlying genetic abnormalities as proposed by the European LeukemiaNet (ELN) risk classification. However, AML is highly heterogenous at the molecular level and standard guidelines are often not straightforwardly applicable. In this study, we explored gene expression-based risk stratification strategies and found that FLT3 and NPM1 transcript level profiles can predict overall survival in de novo AML. Methods: The Cancer Genome Atlas AML (TCGA-LAML) project’s normalized RNA-Seq transcriptome profile (n=158) published in 2013 was analyzed with MATLAB software. "High” or “low” level of each gene was determined by the median RPKM of the cohort used as cutoff. P-values were obtained from Cox proportional hazards regression model. Results: The low-FLT3 level group was associated with superior median OS (mOS) compared to high-FLT3 group (24 vs. 16 months; p = 0.02), whereas high-NPM1 level group was associated with superior mOS compared to low-NPM1 group (26 vs. 12 months; p = 0.03). The mOS for high-FLT3/low-NPM1 and low-FLT3/high-NPM1 groups were 9 months and 27 months, respectively (p = 0.001). In high-FLT3/low-NPM1 and low-FLT3/high-NPM1 groups, composition of Cancer and Leukemia Group B (CALGB) cytogenetic risk category [favorable, intermediate, adverse] was [9%, 73%, 18%] and [32%, 49%, 19%], respectively; composition of French-American-British (FAB) classification [M0, M1, M2, M3, M4, M5, M6, M7] was [15%, 27%, 3%, 6%, 24%, 24%, 0%, 0%] and [3%, 14%, 41%, 19%, 22%, 0%, 0%, 3%], respectively; composition of FLT3/NPM1c mutations [ wt/wt, mut/wt, wt/mut, mut/mut, NOS] was [45%, 18%, 18%, 18%, 0%] and [61%, 14%, 7%, 14%, 2%], respectively. Conclusions: We demonstrate a de novo AML risk categorization method solely based on FLT3 and NPM1 RNA-Seq transcript levels. The mOS of high-FLT3/low-NPM1 group resembled that of ELN "adverse" risk group, whereas the mOS of low-FLT3/high-NPM1 group resembled that of ELN "favorable" risk group. High-FLT3/low-NPM1 group was composed of fewer "favorable” but more “intermediate” CALGB risk categories compared to low-FLT3/high-NPM1 group. Notably, considerably more FAB M0, M1 and M5 but fewer M2 and M3 classes were enriched in high-FLT3/low-NPM1 group compared to low-FLT3/high-NPM1 group. We also note approximately half of the cases analyzed were FLT3 and NPM1 wild-types and speculate FLT3 and NPM1 transcript profiles may represent a global oncogenic state regardless of the underlying FLT3 or NPM1 mutations. This is also supported by the previously reported FLT3 mutation-like transcriptomic profiles observed in FLT3 wild-type AML cases1). Reference: 1) Mosquera Orgueira A, et al. Gene expression profiling identifies FLT3 mutation-like cases in wild-type FLT3 acute myeloid leukemia. PLoS One. 2021 Feb 16;16(2):e0247093

Myelomonocytic and monocytic acute myeloid leukemia demonstrate comparable poor outcomes with venetoclax-based treatment: a monocentric real-world study.

Venetoclax (VEN), a BCL-2 inhibitor, has transformed treatment strategies for elderly and unfit acute myeloid leukemia (AML) patients by significantly improving response rates and survival. However, the predictive factors for VEN efficacy differ from traditional chemotherapy. The clinical relevance of the FAB (French-American-British) monocytic subtype, including M4 and M5, has been debated as a marker for VEN resistance. This real-world study examined 162 newly diagnosed (ND) and 85 relapsed/refractory (R/R) AML patients who received VEN-based therapy at West China Hospital, Sichuan University, from January 2019 to January 2023. We retrospectively collected clinical and treatment data from electronic medical records. The median age of the cohort was 55.5years (range: 16.5-83.5). The composite complete remission (cCR) rate in the entire cohort was 60.7%. Specifically, among newly diagnosed (ND) patients, FAB monocytic subtypes exhibited lower cCR compared to non-monocytic subtypes (55.1% vs. 76.3%, P = 0.007). Additionally, there were no significant differences observed between M4 and M5 subtypes, both in the ND group (61.7% vs. 40.9%, p = 0.17) and the R/R group (38.2% vs. 40%, p > 0.9). Furthermore, the median follow-up was 238 (range: 7-1120) days. ND patients with monocytic subtypes had shorter overall survival compared to non-monocytic subtypes (295days vs. not reached, p = 0.0017). Conversely, R/R patients showed no such difference (204 vs. 266days, p = 0.72). In summary, our study suggests that the FAB monocytic subtype can predict VEN resistance and shorter survival in ND AML patients. Moreover, there is no significant distinction between M4 and M5 subtypes.

High Mitochondrial Protein Expression as a Potential Predictor of Relapse Risk in Acute Myeloid Leukemia Patients with the Monocytic FAB Subtypes M4 and M5.

AML is a highly aggressive and heterogeneous form of hematological cancer. Proteomics-based stratification of patients into more refined subgroups may contribute to a more precise characterization of the patient-derived AML cells. Here, we reanalyzed liquid chromatography-tandem mass spectrometry (LC-MS/MS) generated proteomic and phosphoproteomic data from 26 FAB-M4/M5 patients. The patients achieved complete hematological remission after induction therapy. Twelve of them later developed chemoresistant relapse (RELAPSE), and 14 patients were relapse-free (REL_FREE) long-term survivors. We considered not only the RELAPSE and REL_FREE characteristics but also integrated the French-American-British (FAB) classification, along with considering the presence of nucleophosmin 1 (NPM1) mutation and cytogenetically normal AML. We found a significant number of differentially enriched proteins (911) and phosphoproteins (257) between the various FAB subtypes in RELAPSE patients. Patients with the myeloblastic M1/M2 subtype showed higher levels of RNA processing-related routes and lower levels of signaling related to terms like translation and degranulation when compared with the M4/M5 subtype. Moreover, we found that a high abundance of proteins associated with mitochondrial translation and oxidative phosphorylation, particularly observed in the RELAPSE M4/M5 NPM1 mutated subgroup, distinguishes relapsing from non-relapsing AML patient cells with the FAB subtype M4/M5. Thus, the discovery of subtype-specific biomarkers through proteomic profiling may complement the existing classification system for AML and potentially aid in selecting personalized treatment strategies for individual patients.

Analysis of FLT3-Activating Mutations in Patients With Acute Myelogenous Leukemia in Jordan: Association With FAB Subtypes and Identification of Subgroups With Poor Prognosis

BackgroundFLT3 mutations are common in acute myeloid leukemia (AML), particularly in French–American–British M2 subtype AML and in cytogenetically normal (CN) AML; however, its incidence in Jordan is poorly studied. An FLT3 mutation implies poor prognosis in AML patients. We aimed to assess the incidence and prognostic value of FLT3 mutations in AML in Jordan. Patients and MethodsOne hundred thirty-two newly diagnosed unselected AML patients were included. Patient data were collected, including demographics as well as morphologic, cytogenetic, and molecular testing results. FLT3 mutations were detected by real-time reverse transcriptase PCR, next-generation sequencing, or both. Survival analysis and comparisons of incidence, remission rate, relapse, and survival outcomes between FLT3-mutated and wild-type groups were done and prognostic factors identified. ResultsFLT3 mutation was detected in 40% of AML patients. The highest incidence was associated with M2 subtype AML (47%) and CN-AML (50%). There was a significant negative association between FLT3 mutations and overall survival (OS), as well as a trend toward improved relapse-free survival, with 3-year OS being 19.17% vs 34.16% (P < .0001) and 33.6% vs 71.0% (P = .085), respectively. Patients with FLT3 mutation had a significantly better complete remission rate after induction (67.9% vs 63.3%, P = .001). Also, OS improved in patients with complete remission (P = .0015) and who then continued to allogeneic hematopoietic cell transplantation compared to FLT3 wild-type patients (P < .001). ConclusionFLT3 mutation is common in Jordanian AML patients, with the highest incidence occurring in patients with M2 or CN disease. It implies a poor prognosis, with poor OS and relapse-free survival, which may be abrogated by early allogeneic transplantation and/or peritransplantation provision of FLT3 inhibitors.

Cellular drug resistance profiles in childhood acute myeloid leukemia: differences between FAB types and comparison with acute lymphoblastic leukemia

AbstractDetermining in vitro drug resistance may reveal clinically relevant information in childhood leukemia. Using the methyl-thiazol-tetrazolium assay, the resistance of untreated leukemic cells to 21 drugs was compared in 128 children with acute myeloid leukemia (AML) and 536 children with acute lymphoblastic leukemia (ALL). The differences between 3 French-American-British (FAB) types (M1/M2, M4, and M5) were also compared. AML was significantly more resistant than ALL to the following drugs, as noted by the median resistance: glucocorticoids (greater than 85-fold), vincristine (4.4-fold), l-asparaginase (6.9-fold), anthracyclines (1.8- to 3.4-fold), mitoxantrone (2.6-fold), etoposide (4.9-fold), platinum analogues (2.4- to 3.4-fold), ifosfamide (3.5-fold), and thiotepa (3.9-fold). For cytarabine and thiopurines, the median LC50 values (the drug concentration that kills 5% of the cells) were equal. Also, busulfan, amsacrine, teniposide, and vindesine showed no significant differences, but the numbers were smaller, and the median LC50 values were 1.3- to 5.2-fold higher in AML. None of the drugs demonstrated greater cytotoxicity in AML. FAB M5 was significantly more sensitive than FAB M4 to most drugs frequently used in AML, as indicated by the following ratios of median sensitivities: the anthracyclines (2.6- to 3.2-fold), mitoxantrone (12.5-fold), etoposide (8.7-fold), and cytarabine (2.9-fold). For etoposide and cytarabine (5.4- and 3.4-fold, respectively) FAB M5 was also significantly more sensitive than FAB M1/M2. FAB M5 was equally sensitive tol-asparaginase and vincristine as ALL. Only 15% of the AML samples were “intermediately” sensitive to glucocorticoids, mainly in FAB M1/M2. The poorer prognosis of childhood AML is related to resistance to a large number of drugs. Within AML, FAB M5 had a distinct resistance pattern. These resistance profiles may be helpful in the rational design of further treatment protocols.

FLT3 internal tandem duplication in 234 children with acute myeloid leukemia: prognostic significance and relation to cellular drug resistance

AbstractFLT3 is a receptor tyrosine kinase involved in the proliferation and differentiation of hematopoietic stem cells. FLT3 internal tandem duplications (FLT3/ITDs) are reported in acute myeloid leukemia (AML) and predict poor clinical outcome. We found FLT3/ITDs in 11.5% of 234 children with de novo AML. FLT3/ITD-positive patients were significantly older and had higher percentages of normal cytogenetic findings or French-American-British (FAB) classification M1/M2 and lower percentages of 11q23 abnormalities or FAB M5. FLT3/ITD-positive patients had lower remission induction rates (70% vs 88%; P = .01) and lower 5-year probability rates of event-free survival (pEF) (29% vs 46%; P = .0046) and overall survival (32% vs 58%; P = .037). Patients with high ratios (higher than the median) between mutant and wild-type FLT3 had significantly worse 2-year EFS rates than FLT3/ITD-negative patients (pEFS 20% vs 61%; P = .037), whereas patients with ratios lower than the median did not (pEFS 44% vs 61%; P = .26). FLT3/ITD was the strongest independent predictor for pEFS, with an increase in relative risk for an event of 1.92 (P = .01). Using an MTT (methyl-thiazol-tetrazolium)-based assay, we studied cellular drug resistance on 15 FLT3/ITD-positive and 125 FLT3/ITD-negative AML samples, but we found no differences in cellular drug resistance that could explain the poor outcomes in FLT3/ITD-positive patients. We conclude that FLT3/ITD is less common in pediatric than in adult AML. FLT3/ITD is a strong and independent adverse prognostic factor, and high ratios between mutant and WT-FLT3 further compromise prognosis. However, poor outcomes in FLT3/ITD-positive patients could not be attributed to increased in vitro cellular drug resistance. (Blood. 2003;102:2387-2394)

Impact of Leukemia Stem Cells Phenotype Expression on Response to Induction Therapy in Acute Myeloid Leukemia Patients.

Laboratory data suggest that acute myeloid leukemia AML originates from a rare population of cells, termed Leukemic Stem Cells (LSCs) or leukemia-initiating cells, which are capable of self-renewal, proliferation and differentiation into malignant blasts. There is a universal agreement that LSCs lie within the CD34+ compartment of hemopoietic cells and most of leukemic stem cells express the interleukin-3 alpha chain receptor, CD123 and lack CD38. This study aimed to estimate the expression of LSC phenotype in AML patients and to correlate it with response to induction therapy. A cohort of 41 patients older than 15 years with newly diagnosed de novo AML were enrolled in this study. They were obtained from the National center of hematology in Baghdad and Baghdad teaching hospital between February and July 2013. The expression of CD34, CD38 and CD123 was assessed by multi-color flow cytometry. LSC positive (LSC+) samples must express CD34 and CD123 and lack the expression of CD38 in >1% of cells. French American British (FAB) classification system was used in this study. After four weeks of induction therapy; three groups were found: those who reached the Complete morphological Remission (CR), those who failed to reach CR and those who died before the assessment of morphological remission. The last two groups were merged for statistical purposes. After the course of induction therapy, 41.46% of patients had complete morphological remission while 58.54% of the studied patients failed to reach complete remission. The Complete Remission (CR) rate was higher (53.33%) in patients who were negative for LSC phenotype than patients who were positive for LSC phenotype (34.61%). LSCs were expressed in 63.41% of AML cases and were in approximate distribution in FAB M3 and non-M3 patients. The expression of LSC phenotype was associated with poor response to induction therapy in AML patients.

Molecular Study of FLT3 gene mutations in Acute Myeloid Leukemia from Pakistan : Correlation with clinicopathological parameters.

Introduction: FLT3 mutations are common genetic changes reported to have prognostic significance in acute myeloid leukemia (AML). Bone marrow/peripheral blood samples of 63 AML Pakistani patients were collected and DNA was isolated.Materials and Methods: The FLT3 internal tandem duplication (ITD) and the D835 activating mutation in the tyrosine kinase domain (TKD) were analyzed by polymerase chain reaction (PCR).Results: Among 63 AML patients, 42 were males and 21 were females with male to female ratio 2.1:1. The age ranged between 15 to 75 years with a median age of 32 years. AML-M2 was the predominant French-American-British (FAB) subtype (32%) followed by M3 (27%), M4 (19%), M5 (6.3%) and M1 (6.3%). The incidence of FLT3/ITD and TKD was 22% and 6.3% respectively. Majority of the FLT3/ITD mutation were detected in AML-M4 (38%) patients while D835 mutation was common in both FAB M1, M2. Presence of mutation was significantly associated with age but significance was not achieved for hyperleukocytosis.Conclusion: This study constitutes the first report from Pakistan reporting significant presence of FLT3/ITD mutations in our adult AML patients with different FAB subtypes Molecular mutation analysis in different cytogenetic groups with follow-up is required to understand the pathogenesis of leukemias and their role as a valuable prognostic marker in our patients.

GATA2 zinc finger 1 mutations are associated with distinct clinico-biological features and outcomes different from GATA2 zinc finger 2 mutations in adult acute myeloid leukemia

Mutations of the GATA binding protein 2 (GATA2) gene in myeloid malignancies usually cluster in the zinc finger 1 (ZF1) and the ZF2 domains. Mutations in different locations of GATA2 may have distinct impact on clinico-biological features and outcomes in AML patients, but little is known in this aspect. In this study, we explored GATA2 mutations in 693 de novo non-M3 AML patients and identified 44 GATA2 mutations in 43 (6.2%) patients, including 31 in ZF1, 10 in ZF2, and three outside the two domains. Different from GATA2 ZF2 mutations, ZF1 mutations were closely associated with French-American-British (FAB) M1 subtype, CEBPA double mutations (CEBPAdouble-mut), but inversely correlated with FAB M4 subtype, NPM1 mutations, and FLT3-ITD. ZF1-mutated AML patients had a significantly longer overall survival (OS) than GATA2-wild patients and ZF2-mutated patients in total cohort as well as in those with intermediate-risk cytogenetics and normal karyotype. ZF1 mutations also predicted better disease-free survival and a trend of better OS in CEBPAdouble-mut patients. Sequential analysis showed GATA2 mutations could be acquired at relapse. In conclusion, GATA2 ZF1 mutations are associated with distinct clinico-biological features and predict better prognosis, different from ZF2 mutations, in AML patients.

Clinical and biological implications of mutational spectrum in acute myeloid leukemia of FAB subtypes M4 and M5.

The mutational spectrum and molecular characteristics of acute myelomonocytic lineage leukemia, namely acute myeloid leukemia (AML) French-American-British (FAB) subtypes M4 and M5, are largely unknown. In order to explore the mutational spectrum and prognostic factors of FAB-M4 and -M5, next-generation sequencing (NGS) was performed to screen for mutated genes and fusion genes relevant to the pathogenesis of AML. Of the 63 patients enrolled in the study, 60% had more than three mutated genes. NPM1 had the highest mutation frequency, followed by DNMT3A, FLT3, NRAS, RUNX1, and TET2. Univariate analysis suggested that age ≥60 years was an independent factor for both poor event-free survival (EFS) and overall survival (OS, P = 0.009, 0.002, respectively), MYH11-CBFβ was associated with better EFS and OS (P = 0.029, 0.016, respectively). However, multivariate analysis was not able to identify any independent risk factor for survival in the cohort of FAB-M4 and -M5 patients, including peripheral white blood cell count, bone marrow blast percentage, MYH11-CBFβ, FLT3-ITD, mutations in NPM1 and DNMT3A, and allogeneic hematopoietic stem cell transplantation (allo-HSCT). Our study provided new insight into the mutational spectrum and molecular characteristics of FAB-M4 and -M5. The clinical implications of the genetic signature of FAB-M4 and -M5 need to be further elucidated by larger studies.

Clinical and Biological Implications of Mutational Spectrum in Acute Myeloid Leukemia of FAB Subtypes M0 and M1

Background/Aims: Acute myeloid leukemia (AML) of French-American-British (FAB) subtypes M0 and M1 are both poorly differentiated AML, but their mutational spectrum and molecular characteristics remain unknown. This study aimed to explore the mutational spectrum and prognostic factors of AML-M0 and M1. Methods: Sixty-five AML patients derived from The Cancer Genome Atlas (TCGA) database were enrolled in this study. Whole-genome sequencing was performed to depict the mutational spectrum of each patient. Clinical characteristics at diagnosis, including peripheral blood (PB) white blood cell counts (WBC), blast percentages in PB and bone marrow (BM), FAB subtypes and the frequencies of known recurrent genetic mutations were described. Survival was estimated using the Kaplan-Meier methods and log-rank test. Univariate and multivariate Cox proportional hazard models were constructed for event-free survival (EFS) and overall survival (OS), using a limited backward elimination procedure. Results: Forty-six patients had more than five recurrent genetic mutations. FLT3 had the highest mutation frequency (n=20, 31%), followed by NPM1 (n=18, 28%), DNMT3A (n=16, 25%), IDH1 (n=14, 22%), IDH2 (n=12, 18%), RUNX1 (n=11, 17%) and TET2 (n=7, 11%). Univariate analysis showed that age ≥60 years and TP53 mutations had adverse effect on EFS (P=0.015, P=0.036, respectively) and OS (P=0.003, P=0.004, respectively), WBC count ≥50×10⁹/L and FLT3-ITD negatively affected EFS (P=0.003, P=0.034, respectively), whereas NPM1 mutations had favorable effect on OS (P=0.035) and allogeneic hematopoietic stem cell transplantation (allo-HSCT) on EFS and OS (all P< 0.001). Multivariate analysis suggested that allo-HSCT and NPM1 mutations were independent favorable prognostic factors for EFS and OS (all P< 0.05), WBC count ≥50×10⁹/L was an independent risk factor for EFS (P=0.002) and TP53 mutations for OS (P=0.043). Conclusions: Our study provided new insights into the mutational spectrum and molecular signatures of AML-M0 and M1. We proposed that FLT3-ITD, NPM1 and TP53 be identified as markers for risk stratification of AML-M0 and M1. Patients with AML-M0 and M1 would likely benefit from allo-HSCT.

Phosphoprotein DIGE profiles reflect blast differentiation, cytogenetic risk stratification, FLT3/NPM1 mutations and therapy response in acute myeloid leukaemia

Acute myeloid leukaemia (AML) is an aggressive blood cancer characterized by a distinct block in differentiation of myeloid progenitors, recurrent chromosomal translocations and gene mutations of which >50% involve signal transduction through dysregulated kinases and phosphatases. In search for novel protein biomarkers for disease stratification we investigated the phosphoproteome in leukaemic cells from 62 AML patients at time of diagnosis using immobilized metal-affinity chromatography, protein separation by two-dimensional differential gel electrophoresis (2D-DIGE) and mass spectrometry before validation by selected reaction monitoring (SRM). Unsupervised clustering found 27 phosphoproteins significantly discriminating patients according to leukaemic cell differentiation (French-American-British (FAB) classification), cytogenetic and mutational (FLT3, NPM1) status or response to chemotherapy. Monocytic differentiation (FAB M4–M5) correlated with enrichment of proteins involved in apoptosis (MOES, ANXA5 and EFHD2). TALDO, a protein associated with thrombocytopenia if down-regulated, was elevated in patients with wild type NPM1 compared to patients with NPM1 mutation. This study demonstrates the potential of quantitative proteomics in AML classification and risk stratification. Biological significancePatients diagnosed with AML are currently categorized according to cellular morphology, cytogenetic alterations and mutations, although the majority of these cellular and genetic alterations have no or unsolved impact on therapy selection or prognosis. We therefore explored the phosphoproteome for abundance changes associated with traditional classifiers to unravel patterns that could stratify patients at the protein level. MOES, ANXA5 and EFHD2 were confirmed by SRM to be correlated to monocytic differentiation, whilst TALDO was elevated in NPM1 wild type patients.

Outcome of Newly Diagnosed Acute Myeloid Leukemia with Hyperleukocytosis: Retrospective Study of JALSG AML201

Introduction: Acute myeloid leukemia (AML) with hyperleukocytosis is considered to have a poor prognosis due to a high early death rate secondary to complications such as disseminated intravascular coagulation (DIC), tumor lysis syndrome (TLS), and leukostasis. The usefulness of pre-treatment reduction of leukemic cells is controversial. We reviewed the clinical characteristics and outcome of adult patients with newly diagnosed AML with or without hyperleukocytosis registered to the Japan Adult Leukemia Study Group (JALSG) AML201study and examined whether early death in induction therapy for this AML subtype influenced the outcome. Methods: We retrospectively reviewed the records of 1,022 patients enrolled in the JALSG AML201 study, which was a phase 3 clinical trial for AML newly diagnosed from December 2001 to December 2005. The JALSG AML201 study administered cytarabine from day 1 to 7 as the induction therapy combined with idarubicin or daunorubicin (Ohtake S, et al. Blood. 2011, 24;117:2358-65.). None of the patients received pre-treatment with oral hydroxyurea or leukapheresis. Patients with performance status (PS) of 4 or severe comorbidities such as septic shock were excluded. Patients9 characteristics and outcomes such as rate of early death (defined as death occurring within the first thirty days of treatment), achievement of complete remission (CR), overall survival (OS) rate and cumulative incidence of recurrence (CIR) were compared between patients with hyperleukocytosis and those without hyperleukocytosis. Result: We analyzed retrospectively the records of 1,057 patients with AML registered with the JALSG AML201 study and excluded 35 patients whose leukocyte count or outcome was not recorded. We found 113 AML patients with an initial leukocyte count greater than 100 × 109L−1 (HiLC group). There were 66 males and 47 females, and the median age was 45 years (range: 16-64). Median of leukocyte count before treatment was 160 × 109L−1 (range: 102-382 × 109L−1). According to the French-American-British (FAB) classification, there were four as M0, thirty-four as M1, fifty-six as M2, thirty as M4, and nineteen as M5. Cytogenetic analysis was performed in 107 patients. Eight patients had favorable karyotype, 90 had intermediate karyotype, and nine had unfavorable karyotype. Fifteen percent of patients with hyperleukocytosis had PS of two or greater. We compared the outcome of this AML subset with 909 patients with a leukocyte count lower than 100 × 109L−1 (median count: 10,900, range: 0.77-99.5× 109L−1) who received the same induction chemotherapy as the JALSG AML201 protocol (LoLC group). There was no significant difference between the two groups for age and sex; median age of the patients in LoLC group was 47 years (range: 15-64) with 542 males and 367 females. The frequency of the patients with a favorable karyotype or PS of 0 or 1 was lower in HiLC group than in LoLC group, whereas the rate of FAB M4 or M5 was higher in HiLC as compared to LoLC group. Eighty-two patients (72.5%) in HiLC group and 714 patients (78.5%) in LoLC group achieved CR. Sixty (53%) and twenty-two (19.5%) achieved CR after one and two cycles of treatment, respectively. In contrast, 577 (63%) and 137 (15%) in LoLC group achieved CR after one and two cycles of chemotherapy, respectively. The rate of CR was not significantly different between two groups (p=0.118). However, 5 year OS was significantly lower in HiLC as compared to LoLC group (26.9% vs. 49.4%, p Conclusion: We conclude that hyperleukocytosis on presentation did not significantly affect the rate of early mortality during the induction phase of the treatment. It is considered that intensive chemotherapy without pre-treatment would be possible if appropriate supportive cares were given to manage fatal complications such as DIC. Disclosures Kiyoi:MSD K.K.: Research Funding; Alexion Pharmaceuticals: Research Funding; AlexionpharmaLLC.: Research Funding; Fujifilm Corporation: Patents & Royalties, Research Funding; Phizer Japan Inc.: Research Funding; Takeda Pharmaceutical Co., Ltd.: Research Funding; JCR Pharmaceutlcals Co.,Ltd.: Research Funding; Sumitomo Dainippon Pharma Co., Ltd.: Research Funding; Novartis Pharma K.K.: Research Funding; Mochida Pharmaceutical Co., Ltd.: Research Funding; Toyama Chemikal Co.,Ltd.: Research Funding; Nippon Boehringer Ingelheim Co., Ltd.: Research Funding; Nippon Shinyaku Co., Ltd.: Research Funding; Astellas Pharma Inc.: Consultancy, Research Funding; Eisai Co., Ltd.: Research Funding; Yakult Honsha Co.,Ltd.: Research Funding; Zenyaku Kogyo Co.LTD.: Research Funding; Kyowa-Hakko Kirin Co.LTD.: Research Funding; Celgene Corporation: Consultancy; Chugai Pharmaceutical Co. LTD.: Research Funding. Naoe:Amgen Astellas BioPharma K.K.: Honoraria; CMIC Co., Ltd.: Research Funding; TOYAMA CHEMICAL CO.,LTD.: Research Funding; Nippon Boehringer Ingelheim Co., Ltd.: Honoraria, Research Funding; Kyowa-Hakko Kirin Co.,Ltd.: Honoraria, Patents & Royalties, Research Funding; Sumitomo Dainippon Pharma Co.,Ltd.: Honoraria, Research Funding; Pfizer Inc.: Research Funding; Astellas Pharma Inc.: Research Funding; Fujifilm Corporation: Honoraria, Patents & Royalties, Research Funding; Bristol-Myers Squibb: Honoraria; Otsuka Pharmaceutical Co.,Ltd.: Honoraria, Research Funding; Celgene K.K.: Honoraria, Research Funding; Chugai Pharmaceutical Co.,LTD.: Honoraria, Patents & Royalties.

Cellular Model of CEBPA N321D Captures Gene Expression Profile in the Transition to Pre-Leukaemic Status

BackgroundC/EBPα plays a pivotal role in myeloid differentiation at the CMP to GMP transition point, where it interacts with other transcription factors (TFs) implicated in haematopoiesis. CEBPA mutations are common in acute myeloid leukaemia (AML), predominantly in patients with M1 and M2 French-American-British (FAB) morphological classifications, but relatively little is understood about the pre-leukaemic alterations caused by mutated CEBPA. Murine models have established N321D as a particularly potent CEBPA mutation which causes AML with high mortality (Togami et al, Experimental Hematology, 2015). We aimed to develop an inducible expression system for CEBPA N321D in a cellular model which replicates early haematopoietic progenitors, to study the effects of this mutation on gene expression profiles relevant for malignant haematopoiesis.MethodsWe constructed a Piggy-bac Tet-on inducible expression system which has a 2A peptide mechanism enabling simultaneous expression of both N321D and mCherry fluorescent protein from the same transcript (Fig. 1). We also constructed a control with inducible expression of mCherry. These two plasmids were then transfected into the mouse progenitor cell line Hoxb8-FL (Redecke et al, Nature Methods, 2013), which is conditionally immortalized and models multipotent myelo-lymphoid progenitors. Single cell clones were established and selected for analysis on the basis of cell growth and mCherry fluorescence on induction. RNA was collected post-induction and without induction at 24, 48 and 72 hours in two replicates each from the N321D clone and from the empty control vector. RNA-seq data was aligned to the mouse genome using STAR aligner, processed to generate high throughput sequencing counts, and finally differential expression analysis was performed between N321D and the control.ResultsDifferential expression analysis identified 172 downregulated and 60 upregulated genes after N321D induction. Further analysis of the 172 downregulated genes against online published datasets of gene expression (Gene Expression Commons, https://gexc.stanford.edu), revealed that 19 of these genes are normally upregulated at the CMP to GMP transition. These include genes such as Hck, Met, Hdac8 and Kdm7a which have been previously implicated in haematological malignancy and which may provide novel insights into the leukaemic process fostered by the CEBPA N321D mutation. To further validate our data, we performed unsupervised hierarchical clustering of previously published microarray data from a large collection of over 400 AML expression profiles (Verhaak et al, Haematologica, 2009) using the genes identified in our study, and found that patient samples who had predominantly FAB classifications M1 and M2 clustered together (Fig. 2A,B), as would be expected in CEBPA-mutated AML.ConclusionsOur inducible expression system has the potential to provide novel insights into altered gene expression caused by induction of mutated CEBPA. In particular, our cellular model replicates an early stage of haematopoiesis, and implicates genes which were not previously known to interact with CEBPA. The importance of these genes in CEBPA N321D-mediated re-configuration of the myeloid transcriptional regulatory network requires further analysis. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Extramedullary Relapse of Acute Myeloid and Lymphoid Leukemia in Children: A Retrospective Analysis.

BackgroundExtramedullary relapse (EMR) is a recurrence of leukemia in sites other than the bone marrow, and it exhibits a relatively rare presentation of relapse of acute leukemia. However, EMR is an important cause of treatment failure among patients with acute leukemia. Therefore, early detection of these relapses may improve the prognosis.ObjectivesTo describe the disease-related demographic and clinical features and radiologic findings for children diagnosed with EMR in acute leukemia.Patients and MethodsThe study was based on 22 children (M: F = 14: 8; mean age 7.30 (2.1 - 15.7) years) with 8 acute myeloid leukemia (AML) and 14 acute lymphoid leukemia (ALL) who had experienced an EMR. Age, gender, clinical symptoms, initial extramedullary disease (EMD), French-American-British (FAB) morphology, cytogenetics, time to and site of EMR, concurrent bone marrow relapse (BMR), radiologic findings, and outcomes were evaluated.ResultsNo definite relationship was found between initial EMD and EMR. A predilection for AML to relapse in the central nervous system (CNS), except for the CSF and bone, and for ALL to relapse in the CSF and kidney seemed to occur. Patients with EMR had a significantly higher incidence of t(8: 21) cytogenetics and FAB M2 and L1 morphologies. EMR accompanied with concurrent BMR occurred in 31.8% of the patients, who exhibited a relatively grave clinical course. Radiologic findings were nonspecific and had a great variety of structure involved, including bulging enhancing mass in the CT scan, hypoechoic mass in the US, and enhanced mass-like lesion in the MRI.ConclusionsKnowledge of the potential sites of EMR, their risk factors, and their clinical and radiologic features may be helpful in the early diagnosis of relapse and planning for therapy.

Lyn, a tyrosine kinase closely linked to the differentiation status of primary acute myeloid leukemia blasts, associates with negative regulation of all-trans retinoic acid (ATRA) and dihydroxyvitamin D3 (VD3)-induced HL-60 cells differentiation.

BackgroundLyn, an import member of Src family kinases (SFKs), is supposed to be implicated in acute myeloid leukemia (AML) pathogenesis and development by participation in AML differentiation, yet the details still remain incompletely understood. The expression status of Lyn and its correlation with multiple clinical parameters including cell differentiation degree, different cytogenetic risk classification, and the activity of myeloperoxidase (MPO) were thus investigated. To address the mechanisms underlying the involvement of Lyn in differentiation induction, the effects of dasatinib, an inhibitor for SFKs including Lyn, on the alterations of all-trans retinoic acid (ATRA)- or dihydroxyvitamin D3 (VD3)-induced differentiation, and c-Myc protein expression were investigated.MethodsPrimary AML blasts were obtained from 31 newly diagnosed AML patients with different French-American-British (FAB) subtypes. The expression of phosphorylated and total Lyn, c-Myc, and CD11b, CD11c and CD15 was analyzed by flow cytometry. The activation of Akt and Erk known to be involved in the regulation of c-Myc expression was investigated using western blotting.ResultsSignificant higher expression levels of total Lyn were observed in AML patients with favorable cytogenetics, higher MPO activity and FAB M2 subtype. A clear positive correlation between the expression levels of Lyn and differentiation status of primary AML blasts was observed. Dasatinib inhibited the expression of phosphorylated Lyn, and further enhanced the differentiation-inducing activity of ATRA and VD3 in HL-60 cells. Augmented downregulation of c-Myc protein expression was observed in the combination treatment with ATRA, VD3 and dasatinib compared to treatment with each reagent alone in HL-60 cells. The suppression of the activation of Akt and Erk was also observed concomitantly.ConclusionsThe expression level of total Lyn is closely linked to the differentiation status of AML blasts. The enhancement of differentiation-inducing activity of ATRA/VD3 by dasatinib suggested that Lyn was associated in the negative regulation of ATRA/VD3-induced HL-60 cells differentiation. The enhancement probably was attributed to the downregulation of c-Myc implicated with the suppression of the activation of Akt and Erk. These results provide novel insights into a possible combinational therapeutic approach by targeting Lyn for AML patients, and offer new possibilities for the combination therapy with VD3 and dasatinib.

Gemtuzumab Ozogamicin (GO) in Infants with Acute Myeloid Leukemia (AML) – Combined Results from the Children’s Oncology Group (COG) Trials, AAML03P1 and AAML0531

Background: Infants <1 year of age with AML are at high risk of early death during induction, pulmonary and infectious toxicities, and treatment related mortality (TRM). Compared with older children, infants are more likely to have higher risk clinical and cytogenetic features. Targeted therapy is needed to improve the outcomes for infants with AML while minimizing toxicities.Objective: To determine if the addition of gemtuzumab ozogamicin (GO) to standard chemotherapy is safe, tolerable, and improves event free survival (EFS) in infants <1 year of age with AML.Methods: Infants >/= 1 month to <1 year of age with de novo AML or <1 month of age with progressive AML were eligible for enrollment on the COG trials AAML03P1 and AAML0531. Infants with acute promyelocytic leukemia, juvenile myelomonocytic leukemia, bone marrow failure syndromes, or Down syndrome were not eligible. The 5-course chemotherapy backbone was identical in both trials. GO 3 mg/m2/dose (0.1 mg/kg for patients with a body surface area <0.6 m2) was given on day 6 of Induction (Ind) I and day 7 of Intensification (Int) II to all patients on AAML03P1 and to randomized patients on the experimental arm of AAML0531. Patients on the control arm of AAML0531 were treated with standard therapy without GO (noGO). Stem cell transplant (SCT) was given following IntI to patients on AAML03P1 with a matched family donor (MFD) and to patients on AAML0531 with high risk (HR) disease or with intermediate risk (IR) disease and a MFD. SCT recipients only received one dose of GO. Patients were removed from protocol if the bone marrow had >/= 20% blasts after IndI on AAML03P1 or >/= 5% blasts after IndII on both studies. Early death (ED) was defined as death during IndI.Results: AAML03P1 enrolled 39 infants from 2003-2005 and AAML0531 enrolled 103 infants from 2006-2010 (Table 1). Median follow up was 5.02 years. The demographics and disease characteristics of infants enrolled on both studies were similar. Compared with enrolled children >/= 1 year of age, infants had higher frequencies of hepatomegaly (p<0.001), splenomegaly (p<0.001), hyperleukocytosis (WBC>100x103/µL, p=0.003) and French-American-British (FAB) M5 (p<0.001), and M7 (p<0.001) AML. Infants had less FAB M1 (p<0.001), M2 (p<0.001), and M4 (p=0.029) AML. There was no difference in CNS disease by age. The frequency of 11q23/MLL rearrangement was highest in infants 0-179 days of age (44%) and significantly decreased with increasing age (p<0.001). Favorable cytogenetics were rare in infants: t(8;21) was not found and inv(16)/t(16;16) was only found in 4 patients. FLT3-ITD HAR was absent in infants. The majority of infants (89%) fell into the IR group and infants were less likely to have had high (HR) or low risk (LR) disease when compared with children >/= 1 year. [Display omitted] The ED rate was higher in younger infants (7 ED, infants 0-179d) when compared with older infants (1 ED, infants 180-364d) (p=0.013). EDs were not increased in infants who received GO vs. noGO (5 vs. 3 ED, p=0.730). The complete remission (CR) rate for infants was 68% at the end of IndII. The 5 year EFS was lower in infants than children >/= 1 year (42 vs. 50%, p=0.001). The 5 year OS for infants was 62%, relapse risk (RR) was 44%, and TRM was 10%. Infants who received GO had improved OS, EFS, and RR, though the differences were not statistically significant (Table 2). [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

A review of AML classification: a single institution experience in a developing country

This study reviewed the distribution of de novo adult acute myeloid leukemia (AML) subtypes classified by both French–American–British (FAB) and World Health Organization (WHO) classifications in Malay patients. We have retrospectively analyzed 135 patients with de novo AML diagnosed in Hospital Universiti Sains Malaysia (HUSM) over the past 10 years. One hundred and thirty cases were classified according to the FAB classification and only 80 by the WHO. Majority of them (86.7 %) presented at the age between 15 and 59 years and minority presented in advance age 60 years and above. For the FAB classification, M2 and M4 subtypes were the commonest (21.5 %) followed by M3 (17.0 %), M5 (16.3 %), M1 and M6 (7.4 %), and M7 (3.7 %) and the least number of patients was M0 (1.5 %). The WHO classification identified 30 (37.5 %) cases as AML with recurrent cytogenetic abnormalities, 43 (53.7 %) cases as AML not otherwise specified (NOS), and 7 (8.75 %) cases as AML with myelodysplasia (MDS)-related changes. The most common genetic feature in AML with recurrent cytogenetic abnormalities was t(15;17)/PML/RARA, followed by t(8;21)/AML1/ETO and inv(16)/CBF/MYH11. We concluded that the classification according to the FAB is still widely used taking into consideration the various limitations especially in a developing country. At the same time, we have progressed to incorporate genetic data in our attempt to stratify patients for the purpose of patients’ management.

The Applicability Of The WHO Classification In Pediatric AML. A NOPHO-AML Study

IntroductionThe World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia was revised in 2008 and is based on genetic characteristics and morphology. The classification incorporates newly recognized entities and emphasizes, more than previously, the pivotal role of cytogenetic abnormalities aiming at identifying biological and clinical entities as basis for a stratified treatment. The classification of acute myeloid leukemia (AML) is primarily based on adult studies. However, the frequency of cytogenetic changes varies among children and adults and the relevance of the 2008 revised WHO classification in pediatric AML has not yet been elucidated. The aim of this study was to evaluate the usability of the WHO classification when applied to a large population-based pediatric AML cohort. MethodsWe included children 0-18 years of age diagnosed with de novo AML in the Nordic countries (Sweden, Norway, Finland, Iceland and Denmark) and Hong Kong treated according to the NOPHO-AML-1993 and 2004 protocols in the period January 1993 to December 2012. Clinical, morphologic, and genetic data were retrieved from the database. Patients with myeloid leukemia of Down syndrome, acute promyelocytic leukemia, and therapy-related AML were excluded. The karyotypes from the Nordic countries were centrally reviewed with annual evaluation of the karyograms by the NOPHO cytogenetic working group. Morphological and molecular analyses and immunophenotyping were carried out at regional centers. The patients were classified according to the revised 2008 WHO classification using genetic parameters and the French-American-British (FAB) classification. ResultsIn the NOPHO database we identified 609 children aged 0-18 years diagnosed with AML. In 13 cases, the karyotype analyses either failed or considered uninformative and were excluded. Among the remaining 596 informative cases (98%), 241 (40%) were categorized as AML with recurrent genetic abnormalities; t(8;21)(q22;q22);RUNX1-RUNX1T1 (n=69), inv(16)(p13.1q22) or t(16;16)(p13.1;q22);CBFB-MYH11 (n=47), t(9;11)(p21;q23);MLLT3-MLL (n=61), t(6;9)(p22;q34);DEK-NUP214 (n=5), inv(3)(q21q26.2) or t(3;3)(q21;q26.2);RPN1-EVI1 (n=1), t(1;22)(p13;q13)/RBM15-MKL1 (n=4), NPM1 mutated (n=13), and CEBPA mutated (n=10). Furthermore, 23 children were classified in the provisional entity AML with FLT3-ITD. Based on the karyotype, 92 children (16%) were classified as AML with myelodysplasia-related cytogenetical changes (AML-MDS). This group was dominated by unbalanced abnormalities (9%) with -7/del(7q) being the most common (4% of the total cohort) and complex karyotypes (6% of the total cohort). AML with balanced myelodysplasia-related changes was found in 0.5%. The largest group was the highly heterogeneous AML not otherwise specified (AML-NOS) (n=263) (44%), and included some of the well-defined 11q23 abnormalities. In the 2001 version of the WHO classification, “AML with abnormalities of 11q23; MLL,” was listed separately, but in the 2008 edition only AML with t(9;11)(p22;q23);MLLT3-MLL was listed as an entity. The AML-NOS cases were sub-classified according to morphology, with FAB M5 being most common, found in 22% of NOS, followed by FAB M1, FAB M2, and FAB M4, all found in 18%.In conclusion, 40% of the children were classified in clinically relevant entities, but the WHO classification allocated 16% of the children to AML-MDS, the relevance is unknown in children, and 44% to the NOS group. This large and unspecified group limits the applicability of the WHO classification in children with AML suggesting that additional considerations are warranted for relevant classification of pediatric AML. Disclosures:No relevant conflicts of interest to declare.

CBFA2T3-GLIS2 fusion transcript is a novel common feature in pediatric, cytogenetically normal AML, not restricted to FAB M7 subtype

AbstractPediatric cytogenetically normal acute myeloid leukemia (CN-AML) is a heterogeneous subgroup of myeloid clonal disorders that do not harbor known mutations. To investigate the mutation spectrum of pediatric CN-AML, we performed whole-transcriptome massively parallel sequencing on blasts from 7 CN-AML pediatric patients. In 3 patients we identified a recurrent cryptic inversion of chromosome 16, encoding a CBFA2T3-GLIS2 fusion transcript. In a validation cohort of 230 pediatric CN-AML samples we identified 17 new cases. Among a total of 20 patients with CBFA2T3-GLIS2 fusion transcript out of 237 investigated (8.4%), 10 patients (50%) did not belong to the French–American–British (FAB) M7 subgroup. The 5-year event-free survival for these 20 children was worse than that for the other CN-AML patients (27.4% vs 59.6%; P = .01). These data suggest that the presence of CBFA2T3-GLIS2 fusion transcript is a novel common feature of pediatric CN-AML, not restricted to the FAB M7 subtype, predicting poorer outcome.