Tyrosine Kinase 3-internal Tandem Duplication Research Articles

Prospective Evaluation of Azacitidine Maintenance Following Allogeneic Hematopoietic Stem Cell Transplantation in Patients with High-Risk Acute Myeloid Leukemia and Myelodysplastic Syndrome

▪Introduction and aim. Relapse following allogeneic hematopoietic stem cell transplantation (HSCT) is a major cause of treatment failure and is associated with a poor prognosis. Overall survivals are around 50% at 5 years following allogeneic HSCT in intermediate and high risk AML. Survivals remain less than 20% in poor-risk and very poor-risk patients based on the cytogenetic profile. Thus, prevention of relapse following allogeneic HSCT remains an unmet clinical need. Low-dose azacitidine maintenance post-HSCT has been shown to augment graft-versus-leukemia effect and may prolong survivals. We aim to prospectively evaluate the effect of azacitidine maintenance following allogeneic HSCT in high risk AML and MDS.Method. Consecutive patients with high-risk acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) in remission following first allogeneic HSCT or second allogeneic HSCT (from the original donor) were recruited. High risk AML in this study comprised patients with poor risk karyotype, secondary AML transformed from underlying MDS, presence of fms-like tyrosine kinase 3-internal tandem duplication (FLT3 -ITD) and non-remission before HSCT. Azacitidine was administered at 100mg daily for 3 days per cycle every 28 days until progression or a maximum of 8 cycles. The clinicopathologic and treatment characteristics were determined. The occurrence of graft-versus-host disease (GVHD) was determined. DNA chimerism was determined in the bone marrow before the initiation of azacitidine, after 4th and 8th cycles of azacitidine and at 1 year. DNA chimerism was determined by quantification of polymorphic short tandem repeat sequences. The progression-free survival (PFS) and overall survival (OS) were determined by Kaplan-Meier analysis.Results. Thirty-four patients with high-risk AML (N=31) and MDS (N=3) were recruited. The median duration of follow-up was 14 months (range: 2 - 44 months). Twenty-two patients received azacitidine maintenance after first allogeneic HSCT, whereas 12 patients received azacitidine maintenance after a second allogeneic HSCT from the same donor following relapse from a first allogeneic HSCT For patients receiving azacitidine after first HSCT, at a median follow-up of 18.5 months (range: 5- 36 months), the median PFS was not reached, and the median OS was 32 months (95% confidence interval [C.I.]: 24.85-39.15). The 24-month PFS and OS were 66.1% and 73.2% respectively. Acute and chronic GVHD occurred in 7 (31.8%) and 17 patients (77%). For patients receiving azacitidine after second HSCT, at a median follow-up of 14 months (range: 9 - 46 months), the median PFS and OS were 9 months (95% C.I.:6.94-11.04) and 14 months (range: 11.77 - 16.23 months). The 24-month PFS and OS were 25% and 14% respectively. Acute and chronic GVHD occurred in 1 (8.3%) and 5 (41.7%) patients respectively. In both groups, 100% donor chimerism was achieved during azacitidine maintenance.Conclusion. Azacitidine maintenance following first allogeneic HSCT resulted in favorable 2-year survivals in selected patients with high-risk AML and MDS. Nevertheless, survivals were poor despite azacitidine maintenance after second allogeneic HSCT from the same donor. Full donor chimerism was maintained during azacitidine maintenance. DisclosuresNo relevant conflicts of interest to declare.

Immunohistochemical detection of cytoplasmic nucleophosmin in formalin-fixed paraffin-embedded marrow trephine biopsies in acute myeloid leukaemia

AimsNucleophosmin (NPM1) gene mutations resulting in cytoplasmic delocalisation of nucleophosmin (NPMc+) are the most common genetic abnormality in acute myeloid leukaemia (AML). In this study, we tested whether immunohistochemical (IHC)...

Metformin synergistically sensitizes FLT3-ITD-positive acute myeloid leukemia to sorafenib by promoting mTOR-mediated apoptosis and autophagy

Mutations of Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), accounting for approximately 30% of patients with acute myeloid leukemia (AML), results in poor therapeutic efficacy and short survival. Sorafenib, an oral multikinase inhibitor, can inhibit FLT3 and improve clinical outcome of FLT3 mutated leukemia. Our current studies have shown that, the antidiabetic drug metformin also exerts anti-leukemic effect by activating p-AMPK and synergistically sensitizes FLT3 mutated AML to sorafenib. Both agents suppress cell proliferation in a dose-dependent manner and induce apoptosis via cell cycle arrest, but does not obviously modulate autophagy marker, light chain 3 (LC3). Mechanistically, in the presence of metformin, the anticancer potential of sorafenib, accompanying with increased LC3 levels, is found to be synergistically enhanced with the remarkably reduced protein expression of the mTOR/p70S6K/4EBP1 pathway, while not appreciably altering cell cycle. Overall, these results show metformin in aid of sorafenib may represent a promising and attractive strategy for the treatment of FLT3-ITD mutated AML.

Quantitative fragment analysis of FLT3-ITD efficiently identifying poor prognostic group with high mutant allele burden or long ITD length.

Mutation of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), which is one of the most frequent genetic alterations, strongly contributes to an increased risk of treatment failure and to poor prognosis. In this study, we established quantitative fragment analysis of FLT3-ITD simultaneously measuring mutant allele burden and length, verified the analytical performance and evaluated the clinical significance in adult acute myeloid leukemia (AML) patients. FLT3-ITD was detected in 73 of 363 adult AML patients (20.1%) and high mutant allelic burden (⩾50%, n=13) and long ITD length (⩾70 base pairs, n=15) were significantly associated with inferior overall survival (OS; P=0.002 and 0.005, respectively) and event-free survival (EFS; P=0.004 and 0.007, respectively). FLT3-ITD poor prognostic group was identified as patients with high allele burden or long ITD length (n=24), which revealed significant adverse clinical outcome for both OS (P<0.001) and EFS (P<0.001). In cytogenetically normal AML, even FLT3-ITD low allele burden and short length was associated with poorer OS (P=0.037) and EFS (P=0.044) than wild type, whose influence was overcome when hematopoietic stem cell transplantation was performed. In minimal residual disease monitoring, FLT3-ITD negativity after consolidation therapy was a valuable predictor of better OS (P<0.001) and EFS (P<0.001). FLT3-ITD poor prognostic group with high mutant allele burden or long ITD length is efficiently identified by quantitative fragment analysis.

Prognostic factors of patients with newly diagnosed acute promyelocytic leukemia treated with arsenic trioxide-based frontline therapy

Prognostic factors for patients with acute promyelocytic leukemia (APL) treated in the context of arsenic trioxide (ATO)-based frontline regimes have not been established clearly. We retrospectively analyzed the clinical features, immunophenotypes, Fms-like tyrosine kinase-3 internal tandem duplication (FLT3-ITD), and outcomes of 184 consecutive newly diagnosed APL patients treated by intravenous ATO-based therapy. The median age was 40 years (14–77 years). The early death rate was 4.9% (9/184 patients). With a median follow-up time of 36 months (9–74 months), the 3-year relapse-free survival (RFS) and overall survival (OS) were 93.3% and 92.2%, respectively. Interestingly, there was no meaningful association between 3-year RFS and initial white blood cell count, FLT3-ITD status, or type of PML–RARA isoforms. In multivariable analysis, the CD56 expression was the only independent risk factor in terms of RFS (hazard ratio, 4.70; P=0.005). These results suggested that ATO-based therapy may ameliorate the unfavorable influence of previously known high-risk features; moreover, CD56 expression remains to be a potentially unfavorable prognostic factor in APL patients.

Outcome of allogeneic hematopoietic stem cell transplantation for cytogenetically normal AML and identification of high-risk subgroup using WT1 expression in association with NPM1 and FLT3-ITD mutations.

According to recent guidelines, cytogenetically normal acute myeloid leukemia (CN AML) is divided into four molecular subgroups based on nucleophosmin-1 (NPM1) and FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations. All subgroups except for isolated NPM1mut are associated with poor prognosis. We retrospectively analyzed 223 patients with CN AML, 156 of whom were treated with standard chemotherapy. For postremission therapy, patients with available donors underwent allogeneic (allo) hematopoietic stem cell transplantation (HSCT) and the rest were treated with autologous HSCT or chemotherapy alone. We first compared the 4 conventional molecular subgroups, and then created another 4 subgroups based on WT1 expression: isolated NPM1mut, NPM1wt/FLT3-ITD-neg with low WT1 or high WT1, and FLT3-ITD-pos CN AML. We finally evaluated 89 patients who were treated with allo HSCT and achieved complete remission after standard chemotherapy. FLT3-ITD CN AML showed the worst outcome irrespective of NPM1mut, and isolated NPM1mut CN AML showed no significant differences compared with NPM1wt/FLT3-ITD-neg CN AML. In contrast, two newly stratified low-risk subgroups (NPM1wt/FLT3-ITD-neg with low WT1 and isolated NPM1mut CN AML) showed higher remission rates with superior overall survival (OS) compared with the other two high-risk subgroups, which showed a higher relapse rate even after allo HSCT. Further analysis showed that higher pre-HSCT expression of WT1 resulted in a higher relapse rate and poorer OS after allo HSCT. For CN AML, a risk-adapted approach using allo HSCT with novel agents should be evaluated with stratification specified by WT1. © 2015 Wiley Periodicals, Inc.

Pretreatment FMS like Tyrosine kinase-3 Internal Tandem duplication (FLT3-ITD) Mutant Allele Burden Does Not Predict Response to the Combination of Sorafenib and Azacytidine in Patients with Relapsed or High Risk Elderly Untreated Acute Myeloid Leukemia

To evaluate if pretreatment FLT3-ITD allele burden is associated with an impact on the response to the combination of sorafenib and azacytidine. Methods: We retrospectively analyzed the clinical records for 56 patients with FLT3-ITD treated with azacytidine and sorafenib between 2009 and 2013. Results: Among the patient, 34 (54%) were male, 15 (24%) had secondary AML and 7 (11%) had therapy-related AML. The median age prior to treatment with azacytidine plus sorafenib was 64 years (range, 20-87), with the median age at initial diagnosis of 63 years (range, 19-86 years). Eastern Cooperative Oncology Group performance status was 2 in 19 patients (31%). The median number of prior therapies received was 2 (range, 0-9); 12 patients were elderly (aged 61 years) without prior therapy who were deemed unfit to receive standard cytotoxic chemotherapy. The median white blood count was 8.9 10 (range, 7.5-13.1 10) and the median bone marrow blast percentage was 56% (range, 0-99%). The median FLT3-ITD allelic burden was 0.73 (range, 0.34-0.93) Median time from diagnosis to treatment with sorafenib and azacytidine was 5.5 months (range, 3 days -27months); cytogenetics was unfavorable in 8 patients (13%), normal karyotype in 30 (48%), and miscellaneous in 24 (39%). Eight (14%) patients achieved a complete response (CR) with 7 patients (13%) achieving CR without platelet recovery (CRp) and 10 (18%) achieving CR without peripheral blood count recovery (CRi); 1 patient (1%) had partial response (PR). The overall response rate was 46%. The OS at 3 months and 12 months were 45% and 24%, respectively. FLT-3 ITD allele burden had no significant impact on overall survival (OS) [HR 0.93, 95% CI (0.79-1.10); p1⁄40.433]. The variables with significant and independent impact on OS were achieving CR/CRp/CRi [HR 0.183, 95% CI (0.77-0.435); p 1⁄4 0.000], and ECOG 2[HR 3.78, 95% CI (1.782-7.843)]. The only variable with a significant impact on the overall response rate was blast percentage [OR 1.025 (1.007-1.043); p 1⁄4 0.007]. FLT3-ITD allele burden had no impact on response rate [OR 0.63 (0.21-1.83) p 1⁄4 0.394]. Conclusion: The FLT3-ITD allele burden in patients with relapsed, refractory, or high-risk untreated AML does not have an impact on the response rate or survival.

Prognostic significance of acquired copy-neutral loss of heterozygosity in acute myeloid leukemia.

Chromosomal abnormalities are important in the diagnosis and prognosis of patients with acute myeloid leukemia (AML). Genomic microarray techniques detect recurrent copy-neutral loss of heterozygosity (cnLOH) in addition to copy number aberrations. However, the clinical utility has not been fully established. Therefore, in the current study, the authors examined the prognostic impact of acquired cnLOH in patients with AML, including complete remission (CR) rate, duration of CR, and overall survival (OS). A total of 112 consecutive patients with AML who were undergoing chromosome genomic array testing (CGAT) at the Seattle Cancer Care Alliance were included in the current study. DNA from the bone marrow or blood was analyzed with a microarray platform with both single-nucleotide polymorphism (SNP) probes and non-SNP probes to identify acquired cnLOH. Results were correlated with cytogenetic, molecular, immunophenotypic, and other clinicopathological findings. Patients with cnLOH demonstrated a shorter duration of CR (hazard ratio, 1.87; P =.04) and worse OS (HR, 1.82; P = .03). Multivariate analyses confirmed the independent predictive value of cnLOH for early disease recurrence (P =.02). These results largely reflected those in patients with intermediate and unfavorable cytogenetics. Most strikingly, 13q cnLOH was found to demonstrate a 6.64-fold higher rate of disease recurrence (P =.006) and 3.45-fold worse OS (P = .02) and was enriched with the FLT3-ITD (Fms-related tyrosine kinase 3-internal tandem duplication) mutation. CnLOH has important prognostic significance in patients with AML. CGAT can replace imbalance fluorescence in situ hybridization and the authors recommend the routine use of CGAT to detect cnLOH, particularly among patients with intermediate-risk cytogenetics.

Coexpression of hyperactivated AKT1 with additional genes activated in leukemia drives hematopoietic progenitor cells to cell cycle block and apoptosis

The phosphatidylinositol 3-kinase/AKT pathway is an integral component of signaling involved in the development of many cancers, including myeloid leukemias such as chronic myeloid leukemia and acute myeloid leukemia (AML). Increased AKT1 activity is frequently seen in AML patients, providing leukemic cells with growth and survival promoting signals. An important aspect of AKT1 function is its involvement in cellular metabolism and energy production. Under some circumstances, strong activation of AKT1 increases oxidative stress, which can cause apoptosis when cells progressively build up excess free radicals. This has been described in hematopoietic cells overexpressing activated AKT1; however, whether this is true in cells coexpressing other genetic events involved in leukemia is not known. This prompted us to investigate the effect of constitutively active AKT1 (myristoylated AKT1) in hematopoietic progenitor cells expressing constitutively active signal transducer and activator of transcription 5, Fms-related tyrosine kinase 3-internal tandem duplication, or antiapoptotic B-cell lymphoma 2. Surprisingly, myristoylated AKT1 was incompatible with proliferation driven by both signal transducer and activator of transcription 5 and Fms-related tyrosine kinase 3-internal tandem duplication, which triggered cell cycle block and apoptosis. Moreover, transplantable cells of B-cell lymphoma 2-transgenic mice were impaired in their engraftment ability to recipient mice when expressing hyperactivated AKT1. This was linked to AKT1-mediated proapoptotic functions and not to impairment in homing to the bone marrow. Although cells expressing hyperactivated AKT1 displayed higher levels of reactive oxygen species both in vitro and in vivo, the addition of the antioxidant N-acetyl-L-cysteine significantly reduced apoptosis. Taken together, the results indicate that constitutive AKT1 activity is incompatible with growth- and survival-promoting ability of other activated genes in AML.

The Combination of Quizartinib with Azacitidine or Low Dose Cytarabine Is Highly Active in Patients (Pts) with FLT3-ITD Mutated Myeloid Leukemias: Interim Report of a Phase I/II Trial

Background: FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutation in acute myeloid leukemia (AML) is associated with early relapse and poor survival. Quizartinib potently and selectively inhibits FLT3 kinase activity. In a phase I and II studies the composite response rate (CRR) was approximately 50% among patients with FLT3-ITD. There is in-vitro synergy between quizartinib and 5-AZA or LDAC. We hypothesize that adding quizartinib to a hypomethylating agent such as 5-azacitidine (AZA) or cytarabine may improve the response rate expected from the use of either agent alone.Objectives: The primary objective of phase I part is to determine the dose limiting toxicity (DLT) and maximally tolerated dose (MTD) of the combination of quizartinib (AC220) with either AZA or low-dose cytarabine (LDAC); for phase II is to determine the clinical activity of both combinations. This planned interim analysis reports on the recommended phase II dose (RP2D) and first futility analysis.Methods: For phase I, patients with relapsed/refractory high-risk myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML) or AML were eligible irrespective of FLT3 mutation and salvage status. For phase II, presence of FLT3-ITD is a requisite. Phase II enrollment is limited to patients >60 years with untreated MDS/CMML/AML, or any age receiving first salvage treatment. Additional eligibilities include performance status ECOG ≤2, adequate organ function, normal electrolytes (potassium, calcium and magnesium). Important exclusions include QTcF> 450 mSec, concomitant drugs that prolong QT/QTc interval or strong CYP3A4 inhibitors or inducers with the exception of antibiotics, antifungals, and antivirals that are used as standard of care.Treatment cycle is defined as 28 days. Treatment comprises of AZA 75 mg/m2 subcutaneously (SQ) or intravenously (IV) for 7 days of every cycle (Days 1-7), or cytarabine 20 mg SQ twice daily for 10 days of every cycle (Days 1-10) along with quizartinib at two planned dose levels: 60 mg (dose level 1) or 90 mg orally daily (dose level 2) uninterrupted. Patients are assigned to AZA or LDAC arm by physician choice or slot availability. Planned accrual for each arm in phase 2 is 26 pts each and an ORR of ≥50% will be considered favorable. Accrual of 26 pts will give a 95% credible interval for overall response rate of (0.32, 0.68). The study will be stopped for toxicity (>30%) and/or futility (ORR <50%) at interim analysis for each arm.Results: Twenty-six (Phase I=12, phase II=14) pts have been enrolled: 18 to AZA arm and 8 to LDAC arm. Median age is 62 years (range, 25-79 years), 7 (27%) are female. Cytogenetics are diploid=14, +8=2, -7=2, miscellaneous=6, 11q and t(8;21)= 1 each. Median number of prior therapies is 2 (range, 0-7), 7 patients received prior FLT3 inhibitor. For both schedules quizartinib 60 mg daily was identified as the recommended phase II dose (RP2D) based on emerging results from separate dose-finding study.Eighteen [5 in LDAC arm (63%) and 13 (72%) in AZA arm; all with FLT3-ITD mutation without D835 mutation] of 26 total pts (69%) have responded (CR=1/ CRp=3/ CRi=2/ MLFS=10/PR=1/HI=1). Among patients with FLT3-ITD (N=22), ORR is 82%. Four of 7 (57%) patients with prior FLT3 inhibitor exposure responded. Median number of days to respond is 57 days (range, 25-102 days). Among responders two patients died (MLFS=1, PR=1): one with gastro-intestinal bleeding and other with progressive pneumonia. Three additional responders have discontinued therapy for stem cell transplant (1), withdrawal of consent (1), and loss of response with emergence of D835 mutation (1). Nine responders (CR=1, CRi=1, CRp=1, PR=1, MLS=5) had >50% reduction of FLT3-ITD allelic burden and 2 additional pts (CR=1, CRi=1) had no detectable FLT3-ITD at response. Number of pts with treatment emergent grade 3/4 toxicities irrespective of attribution include hypokalemia (15), hypophosphatemia (5), hyponatremia (4), hypocalcemia (4), hyperbilirubinemia (3), increase in ALT (1), hypernatremia (1hyperglycemia (1), hypotension (1), QTcF prolongation (1, grade 3).Conclusion: Combination of quizartinib and AZA or LDAC is highly active among patients with AML/MDS/CMML with FLT3-ITD . Response rates appear higher than expected with either agent alone. Clinically significant QTcF prolongation is infrequent. Accrual to both arms of the current trial continues. DisclosuresCortes:Ambit Biosciences: Research Funding.

Hematopoietic cell transplantation in patients with intermediate and high-risk AML: results from the randomized Study Alliance Leukemia (SAL) AML 2003 trial.

The optimal timing of allogeneic hematopoietic stem cell transplantation (HCT) in acute myeloid leukemia (AML) is controversial. We report on 1179 patients with a median age of 48 years who were randomized upfront. In the control arm, sibling HCT was scheduled in the first complete remission for intermediate-risk or high-risk AML and matched unrelated HCT in complex karyotype AML. In the experimental arm, matched unrelated HCT in first remission was offered also to patients with an FLT3-ITD (FMS-like tyrosine kinase 3-internal tandem duplication) allelic ratio >0.8, poor day +15 marrow blast clearance and adverse karyotypes. Further, allogeneic HCT was recommended in high-risk AML to be performed in aplasia after induction chemotherapy. In the intent-to-treat (ITT) analysis, superiority of the experimental transplant strategy could not be shown with respect to overall survival (OS) or event-free survival. As-treated analyses suggest a profound effect of allogeneic HCT on OS (HR 0.73; P=0.002) and event-free survival (HR 0.67; P<0.001). In high-risk patients, OS was significantly improved after allogeneic HCT in aplasia (HR 0.64; P=0.046) and after HCT in remission (HR 0.74; P=0.03). Although superiority of one study arm could not be demonstrated in the ITT analysis, secondary analyses suggest that early allogeneic HCT is a promising strategy for patients with high-risk AML.

FLT3 Gene Mutation in Childhood Acute Leukemia: A Preliminary Study

Introduction. FLT3 is a tyrosine kinase receptor involved in the proliferation and differentiation of hematopoietic stem cells. There are two types of common FLT3 gene mutation, internal tandem duplication and the D835 mutation, which are known to be associated with a poor clinical outcome in acute leukemia patients. Methods. This study evaluates the incidence of FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) in 38 pediatric patients diagnosed with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) in Hospital Universiti Sains Malaysia. DNA extraction was done from archive bone marrow samples to determine FLT3-ITD mutations using polymerase chain reaction. Results. In this pediatric series, the age ranges were 2–14 years. However, no FLT3-ITD mutations were detected in any of the samples. Conclusion. This preliminary study suggested that the incidence of FLT3 gene mutation most probably was very low in pediatrics patients diagnosed with acute leukemia. A further study with larger number of patient samples is necessary to confirm the findings and to further appreciate the prognostic value of FLT3-ITD mutation among pediatrics patients.

SIRT1 prevents genotoxic stress-induced p53 activation in acute myeloid leukemia

AbstractSIRT1 is an important regulator of cellular stress response and genomic integrity. Its role in tumorigenesis is controversial. Whereas sirtuin 1 (SIRT1) can act as a tumor suppressor in some solid tumors, increased expression has been demonstrated in many cancers, including hematologic malignancies. In chronic myeloid leukemia, SIRT1 promoted leukemia development, and targeting SIRT1 sensitized chronic myeloid leukemia progenitors to tyrosine kinase inhibitor treatment. In this study, we investigated the role of SIRT1 in acute myeloid leukemia (AML). We show that SIRT1 protein, but not RNA levels, is overexpressed in AML samples harboring activating mutations in signaling pathways. In FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD)+-cells protein, expression of SIRT1 is regulated by FLT3 kinase activity. In addition, SIRT1 function is modulated via the ATM-DBC1-SIRT1 axis in a FLT3-ITD-dependent manner. In murine leukemia models driven by MLL-AF9 or AML1-ETO coexpressing FLT3-ITD, SIRT1 acts as a safeguard to counteract oncogene-induced stress, and leukemic blasts become dependent on SIRT1 activity. Pharmacologic targeting or RNAi-mediated knockdown of SIRT1 inhibited cell growth and sensitized AML cells to tyrosine kinase inhibitor treatment and chemotherapy. This effect was a result of the restoration of p53 activity. Our data suggest that targeting SIRT1 represents an attractive therapeutic strategy to overcome primary resistance in defined subsets of patients with AML.

Distribution and levels of cell surface expression of CD33 and CD123 in acute myeloid leukemia.

Owing to the more recent positive results with the anti-CD33 immunotoxin gemtuzumab ozogamicin, therapy against acute myeloid leukemias (AMLs) targeting CD33 holds many promises. Here, CD33 and CD123 expression on AML blasts was studied by flow cytometry in a cohort of 319 patients with detailed information on French–American–British/World Health Organization (FAB/WHO) classification, cytogenetics and molecular aberrations. AMLs of 87.8% express CD33 and would therefore be targetable with anti-CD33 therapies. Additionally, 9.4% of AMLs express CD123 without concomitant CD33 expression. Thus, nearly all AMLs could be either targeted via CD33 or CD123. Simultaneous presence of both antigens was observed in 69.5% of patients. Most importantly, even AMLs with adverse cytogenetics express CD33 and CD123 levels comparable to those with favorable and intermediate subtypes. Some patient groups with unfavorable alterations, such as FMS-related tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations, high FLT3-ITD mutant/wild-type ratios and monosomy 5 are even characterized by high expression of CD33 and CD123. In addition, blasts of patients with mutant nucleophosmin (NPM1) revealed significantly higher CD33 and CD123 expression pointing toward the possibility of minimal residual disease-guided interventions in mutated NPM1-positive AMLs. These results stimulate the development of novel concepts to redirect immune effector cells toward CD33- and CD123-expressing blasts using bi-specific antibodies or engineered T cells expressing chimeric antigen receptors.

Analysis of class I and II aberrations in Iraqi childhood acute myeloid leukemia using filter paper cards

The lack of molecular diagnosis in the field of cancer in Iraq has motivated us to perform a genetic analysis of pediatric acute myelogenous leukemia (AML), including class I and II aberrations. Peripheral blood or bone marrow cells were collected from 134 AML children aged ≤15years. Flinders Technology Associates (FTA) filter paper cards were used to transfer dried blood samples from five Iraqi hospitals to Japan. DNA sequencing was performed to identify class I mutations. Nested RT-PCR was used to detect class II aberrations, except that MLL rearrangement was detected according to long distance inverse-PCR. NPM1 and FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations were analyzed by GeneScan using DNA template. Among 134 Iraqi pediatric AML samples, the most prevalent FAB subtype was M2 (33.6%) followed by M3 (17.9%). Class I mutations: 20 (14.9%), 8 (6.0%), and 8 (6.0%) patients had FLT3-ITD, FLT3-TKD, and KIT mutations, respectively. Class II mutations: 24 (17.9%), 19 (14.2%), and 9 (6.7%) children had PML-RARA, RUNX1-RUNX1T1, and CBFB-MYH11 transcripts, respectively. MLL rearrangements were detected in 25 (18.7%) patients. NPM1 mutation was detected in seven (5.2%) cases. Collectively, approximately 30% of AML children were proved to carry favorable prognostic genetic abnormalities, whereas approximately 10% had high FLT3-ITD allelic burden and needed a special treatment plan including allogeneic hematopoietic stem cell transplantation. Acute promyelocytic leukemia (APL) was frequent among Iraqi pediatric AML. It is likely that molecular diagnosis using FTA cards in underdeveloped countries could guide doctors towards an appropriate treatment strategy.

Hyperthyroidism with concurrent FMS-like tyrosine kinase 3-internal tandem duplication-positive acute promyelocytic leukemia: A case report and review of the literature

Neutropenia is a common side-effect in hyperthyroid patients with long-term use of antithyroid drugs. This may be caused by drug-induced immune dysfunction or increased thyroxine hematologic toxicity, which usually returns to normal after medication is discontinued or the hyperthyroidism becomes well controlled. However, hyperthyroidism with pancytopenia is extremely rare. The current case report presents a hyperthyroid patient complicated with pancytopenia who had taken antithyroid drugs for 14 years. Bone marrow analysis revealed primary leuokocytes, indicating M3 acute leukemia. Genetic analysis revealed promyelocytic leukemia-retinoic acid receptor α fusion and FMS-like tyrosine kinase 3-internal tandem duplication. The genetic abnormality was also associated with thyroid hormonal functions. After a standard anti-M3 regimen was administed, the patient achieved complete remission and maintained stable thyroid functions. To the best of our knowledge, this is the first reported case of a patient with hyperthyroidism acquiring M3 leukemia harboring the FMS-like tyrosine kinase 3-internal tandem duplication.

Prognostic implications of NPM1 mutations and FLT3 internal tandem duplications in Egyptian patients with cytogenetically normal acute myeloid leukemia

Nucleophosmin (NPM1) and fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) gene mutations represent the most frequent molecular aberrations in patients with cytogenetically normal-acute myeloid leukemia (CN-AML). We analyzed the prognostic impact of these mutations and their interactions in adults with CN-AML. NPM1 mutation (NPM1mut) and FLT3-ITD mutation (FLT3-ITD+) were analyzed by polymerase chain reaction and GeneScan assays of bone marrow samples obtained from newly diagnosed 104 CN-AML patients. FLT3-ITD+ and NPM1mut were detected in 36 (34.6%) and 30 (28.8%) out of 104 subjects, respectively, 16 cases (15.4%) had double NPM1mut/FLT3-ITD+. The incidence of FLT3-ITD+ was significantly higher in the NPM1mut group than in the NPM1 wild (NPM1wt) group (P = 0.018). Statistical analysis revealed that isolated NPM1mut group had a better clinical outcomes in terms of higher complete response (CR) rate (P = 0.01) and a trend towards favorable overall survival (OS) and disease-free survival (DFS) (P = 0.28, 0.40, respectively). In contrast, the isolated FLT3-ITD+ group had an unfavorable outcome in terms of lower CR rate (P = 0.12), shorter OS, and DFS (P < 0.0001 for both). The NPM1mut/FLT3-ITD-group had the best OS and DFS, while the NPM1wt/FLT3-ITD+ group had the worst OS and DFS than other groups (NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD−) (P < 0.0001 for both). Multivariate Cox regression analysis showed that age and FLT3/ITD+ were independent poor prognostic factors for OS (P = 0.006, <0.0001, respectively), while FLT3/ITD+ was independent predictor for DFS (P = 0.04). However, NPM1mut did not have a significant impact on OS and DFS. In conclusion, adult patients with CN-AML carrying isolated NPM1mut and isolated FLT3-ITD+ exhibit different clinical outcomes than those with NPM1mut/FLT3-ITD+ or NPM1wt/FLT3-ITD−. Patients with NPM1mut/FLT3-ITD− had the best prognosis in terms of higher CR, OS, and DFS, while those with NPM1mut/FLT3-ITD+ had the worst CR rate, and NPM1wt/FLT3-ITD+ had the lowest OS and DFS.

The Nucleophosmin-1 Splice Variant Analysis Provides More Important Information On Prognosis Than NPM1 Mutational Status In Acute Myeloid Leukemia

▪ BackgroundThe process of mRNA splicing has been reported to play an important role in human disease development and many cancer-related genes are regulated by alternative splicing. In addition, first analyses of alternative splicing in bone marrow of AML samples identified novel splice variants specific for AML patients in comparison to normal cells such NOTCH2, CD13 and FLT3. Recently, NPM1 mutations have been included as novel provisional entity within the WHO classification of AML. This new entity bears distinct genetic, pathological and clinical features. Of particular importance is the fact that mutations in NPM1 without concomitant FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations identifies a group of cytogenetically normal (CN) AML patients with favorable prognosis.Since splicing variants play an important role in cellular functioning and splicing factor mutations have been reported in myeloid tumors including AML, the current study focuses on the characterization of NPM1splicing variants expression as well as its impact on the biology and prognosis of AML patients. MethodsFor 104 samples (52 CN-AML and 52 patients samples with cytogenetic aberrations) qRT-PCR was performed. For sensitivity data normalization β-actin (ACTB)was analyzed. Quantity mean values for gene expression were calculated according to the Standard Curve method.In this first cohort of patients total expression of NPM1 (Rt) as well as levels of the three splicing variants of NPM1 were evaluated: R1 that translates exon 1 to 9 and 11 to 12, R2 which contains exons 1 to 10 and R3 that lacks exons 8 and 10.We found prognostic significance of the expression level of NPM1-R2, therefore we decided to validate the prognostic significance of the expression of NPM1-R2 in independent cohort of AML patients. We consolidated 104 patients previously analyzed with 87 patients from the new cohort and preformed the final analysis for NPM1-R2 in total 191 cases. The existence of NPM1-R2 at the protein level was evaluated with the use of Western Blot technique. The cellular localization of NPM-1 was assessed by immunohistochemistry and analyzed with the respect to NPM1-R2 expression. ResultsTotal expression as well as expression of splicing variants R1 and R3 were significantly higher in 104 AML patients compared to healthy volunteers (HVs)with a median expression of 8.587 vs 0.928 (p= 0.001), 1.729 vs 0.5485 (p=0.014), and 2.535 vs 0.108 (p<0.0001), respectively.We evaluated the existence of NPM1-R2 at the protein in AML samples as well as AML cell line KG1. We found that the expression of R2 splicing variant was significantly higher in all AML patients compared to HVs with a median expression of 1.64 vs 0.33 (p= 0.009, n=191)). We have found no differences between groups of AML patients with and without NPM1 mutations (1.21 vs 0.82, p= 0.13). High R2 splicing variant expression was associated with longer OS when CN-AML patients were analyzed (880 vs 438 days, p= 0.028), but there was no association with OS in case of high or low R2 expression in all AML patients. Longer OS was observed in CN-AML patients with high R2 expression without concomitant FLT3-ITD mutations compared to the rest of groups (p<0.0001). Most importantly, in our cohort of CN-AML cases survival differences seen between the established ELN groups according to a NPM1/FLT3-ITD stratification were less impressive than between groups stratified according to R2 expression combined with FLT3-ITD mutational status. ConclusionSince the R2 splicing variant represents a truncated form of NPM1 gene due to the of the lack of exons 11 and 12 (coding for the domain responsible for nucleolar localization of the protein), this isoform mostly localizes in the nucleoplasm, and thus might also have a biological impact in the malignant cells. Most importantly, in our cohort of cases survival differences seen between the established ELN groups according to a NPM1/FLT3-ITD stratification were less impressive than between groups stratified according to R2 expression combined with FLT3-ITD mutational status. In summary, the expression of NPM1-R2 might be of biological importance for CN-AML patients. Moreover, R2 splice variant provides prognostic value for CN-AML patients and should be assessed in addition the NPM1 mutational status. Disclosures:Schlenk:Amgen: Research Funding; Pfizer: Research Funding; Novartis: Research Funding; Chugai: Research Funding; Ambit: Honoraria.

Aleukemic cutaneous myeloid sarcoma

Aleukemic cutaneous myeloid sarcoma (CMS) represents an important yet rare entity denoting the presence of a cutaneous myeloid leukemic infiltrate without concurrent peripheral blood or bone marrow disease. The clinicopathologic diagnosis remains elusive due to isolated skin findings and variable immunostaining. Cytogenetic and molecular findings have infrequently been reported. Twenty-five patients with CMS were identified in the Massachusetts General Hospital pathology database between 2004 and 2012. Patients were excluded if concurrent blood or marrow acute myeloid leukemia (AML), myelodysplastic syndrome or lymphoproliferative disorder were diagnosed. Three patients were identified: a neonate with recurrent CMS and marrow disease that never met diagnostic criteria for AML and two patients relapsing as CMS without concurrent blood or marrow disease following chemotherapy-induced complete remission. Histology showed atypical mononuclear cell interstitial dermal infiltrates. All cases were CD68+, lysozyme+ and CD117-; one of two were CD34+; two of three were myeloperoxidase negative. 11q23 rearrangement, t(1;14), NPM1 (nucleophosmin I), FLT3-ITD (Fms-like tyrosine kinase 3-internal tandem duplication), and novel FLT3-D835 mutations were identified. An isolated atypical cutaneous infiltrate may represent aleukemic CMS and should prompt a search for other extramedullary sites of involvement. Immunohistochemistry, molecular and cytogenetic studies can help differentiate aleukemic CMS from benign and malignant, monocytic and histiocytic mimickers, and may potentially indicate therapy and prognosis.

FLT3-ITD and MLL-PTD influence the expression of MDR-1, MRP-1, and BCRP mRNA but not LRP mRNA assessed with RQ-PCR method in adult acute myeloid leukemia

Fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) and mixed-lineage leukemia gene-partial tandem duplication (MLL-PTD) are aberrations associated with leukemia which indicate unsatisfactory prognosis. Downstream regulatory targets of FLT3-ITD and MLL-PTD are not well defined. We have analyzed the expression of MDR-1, multidrug resistant protein-1 (MRP-1), breast cancer resistance protein (BCRP), and lung resistance protein (LRP) messenger RNA (mRNA) in relation to the mutational status of FLT3-ITD and MLL-PTD in 185 acute myeloid leukemia (AML) adult patients. The real-time quantitative polymerase chain reaction method was performed to assess the expression of the MDR-1, MRP-1, BCRP, and LRP mRNA, and the results were presented as coefficients calculated using an intermediate method according to Pfaffl's rule. Significantly higher expressions of MDR-1 mRNA were found in patients who did not harbor FLT3-ITD (0.20 vs. 0.05; p = 0.0001) and MRP-1 mRNA in patients with this mutation (0.96 vs. 0.70; p = 0.002) and of BCRP mRNA in patients with MLL-PTD (0.61 vs. 0.38; p = 0.03). In univariate analysis, the high expression of MDR-1 mRNA (≥0.1317) negatively influenced the outcome of induction therapy (p = 0.05), whereas the high expression of BCRP mRNA (≥1.1487) was associated with a high relapse rate (RR) (p = 0.013). We found that the high expression of MDR-1 (≥0.1317), MRP-1 (≥0.8409), and BCRP mRNA (≥1.1487) significantly influenced disease-free survival (DFS; p = 0.059, 0.032, and 0.009, respectively) and overall survival (0.048, 0.014, and 0.059, respectively). Moreover, a high expression of BCRP mRNA (≥1.1487) proved to be an independent prognostic factor for RR (p = 0.01) and DFS (p = 0.002) in multivariate analysis. The significant correlation between the expression of MDR-1, MRP-1, and BCRP mRNA and FLT3-ITD or MLL-PTD in AML patients requires further investigation.