Myelodysplastic Syndrome/myeloproliferative Neoplasm Research Articles

CG '806, a First-in-Class Pan-FLT3/BTK Inhibitor, Exhibits Potent Growth Inhibition As a Single Agent and in Combination with a BET Bromodomain Inhibitor or a Bcl2 Inhibitor on Primary AML and CLL Patient Samples

CG '806, a First-in-Class Pan-FLT3/BTK Inhibitor, Exhibits Potent Growth Inhibition As a Single Agent and in Combination with a BET Bromodomain Inhibitor or a Bcl2 Inhibitor on Primary AML and CLL Patient Samples

Endleukemia Assay v1: Enabling NGS-Based Comprehensive Routine Molecular Profiling of Leukemias in Routine Clinical Care

Background: Molecular biomarkers provide diagnostic, prognostic, predictive and minimal residual disease (MRD) information and constitute an integral part of diagnostic workup of hematologic neoplasms. Since a variety of different hematologic disorders can often show non-specific clinical symptoms as well as laboratory findings, the initial diagnostic workup needs to be optimized for timely and efficient coverage of a broad range of differential diagnoses. We developed a customized 81-gene panel, EndLeukemia Assay v1, for comprehensive genetic characterization of disorders that include bone marrow (BM) and peripheral blood (PB). The biomarkers on the panel cover genetic alterations in myeloid neoplasms (acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), myelodysplastic syndrome/myeloproliferative neoplasms (MDS/MPN), aplastic anemia (AA), acute lymphoblastic leukemia (ALL), hairy cell leukemia, T-large granular lymphocytic leukemia (T-LGL) and T-prolymphocytic leukemia (T-PLL).Materials and Methods: Genomic DNA was isolated from fresh BM aspirate/PB or formalin-fixed paraffin-embedded (FFPE) BM clot specimens. Either entire coding sequences or limited exons/hotspots for 81-gene target genes were captured from 250 ng DNA using the hybridization-based HaloPlexTM target enrichment system (Agilent Technologies, Santa Clara, CA). These genes include A NKRD26, ASXL1, ASXL2, BCOR, BCORL1, BRAF, BRINP3, CALR, CBL, CBLB, CBLC, CEBPA, CREBBP, CRLF2, CSF3R, CUX1, DDX41, DNMT3A, EED, ELANE, ETNK1, ETV6, EZH2, FBXW7, FLT3, GATA1, GATA2, GFI1, GNAS, HNRNPK, HRAS, IDH1, IDH2, IKZF1, IL2RG, IL7R, JAK1, JAK2, JAK3, KDM6A, KIT, KMT2A, KRAS, MAP2K1, MPL, NF1, NOTCH1, NPM1, NRAS, PAX5, PHF6, PIGA, PML, PRPF40B, PTEN, PTPN11, RAD21, RARA, RUNX1, SETBP1, SF1, SF3A1, SF3B1, SH2B3, SMC1A, SMC3, SRSF2, STAG1, STAG2, STAT3, STAT5A, STAT5B, SUZ12, TERC, TERT, TET2, TP53, U2AF1, U2AF2, WT1, and ZRSR2. The panel design incorporated molecular barcodes to improve accuracy and sensitivity. Bidirectional paired-end sequencing was performed using the Illumina Miseq platform (Illumina, San Diego, CA). Variant calling was performed using Agilent SureCall software v3.5 and an in-house developed bioinformatics pipeline. Incorporation of single nucleotide polymorphisms (SNP) allows detection of sample identification errors and improves patient safety.Results: During the validation studies, high concordance was observed for missense mutations, insertions/deletions (indels), and selected copy number aberrations (CNAs) when compared with orthogonal methods. Under standardized conditions, a minimum average coverage depth of 3000x is achieved across the entire target region. The analytical sensitivity of the assay was established at 5% using a per base coverage cut-off of 250x. Of note, >90% of the CEBPA coding sequence, which is challenging to sequence due to a high GC component, was covered at >250x coverage depth. Copy number alterations including KMT2A partial tandem duplications (KMT2A -PTD) and IKZF1 deletions were detected successfully. Initial validation of FFPE tissue shows 100% concordance for all mutation calls for matched fresh and FFPE sample pairs. The ability to provide critical diagnostic and prognostic information across mutation hotspots from FFPE tissue if a fresh PB/BM sample is not available improves patient care. The top 25 mutations in the first 500 patient samples across different clinical indications are shown in the figure below. In addition, efficient panel design allowed uniform testing of follow-up bone marrow samples for the detection of MRD and clonal evolution.Conclusion: EndLeukemia assay v1 allowed comprehensive molecular profiling of a variety of hematologic neoplasms in routine clinical testing. Routine molecular biomarker profiling can be facilitated by incorporating smart design features in clinical NGS panels. [Display omitted] DisclosuresKantarjian:Delta-Fly Pharma: Research Funding; Novartis: Research Funding; ARIAD: Research Funding; Pfizer: Research Funding; Amgen: Research Funding; Bristol-Meyers Squibb: Research Funding.

Gender-related differences in the outcomes and genomic landscape of patients with myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes.

Myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndromes show a male predominance and men with MDS/MPN have worse outcomes, but it is unknown if the mutational burden differs between genders. We reviewed 167 patients with MDS/MPN and found that men had worse overall survival [hazard ratio (HR) 2·09, 95% confidence interval (CI) 1·16-3·75; P=0·013] independent of subtype, Revised International Prognostic Scoring System score and age at diagnosis. We analysed the genomic data of a subset of 100 patients. Men had 0·88 more somatic mutations on average (95% CI 0·20-1·56, P=0·011) independent of subtype, sample source and blast percentage. More somatic mutations was associated with a higher incidence of transformation to acute myeloid leukaemia (subdistribution HR 1·30, 95% CI 1·01-1·70; P=0·046). Men had 0·70 more mutations in high-risk genes [additional sex combs like-1 (ASXL1), enhancer of zeste homolog 2 (EZH2), Runt-related transcription factor 1 (RUNX1), SET binding protein 1 (SETBP1), NRAS proto-oncogene, GTPase (NRAS), stromal antigen 2 (STAG2)] on average (95% CI 0·11-1·29, P=0·021), and 13-times higher odds of harbouring an EZH2 mutation (95% CI 1·64-102·94, P=0·015). The presence of an EZH2 mutation was associated with worse survival among men (HR 2·98, 95% CI 1·1-8·0; P=0·031). Our present findings suggest that the worse outcomes in men with MDS/MPN are associated with a higher number of somatic mutations, especially in high-risk genes. These results warrant validation in larger cohorts and investigation of the underlying mechanisms.

Isolated CNS relapse in FLT 3 mutation positive CMML post allogeneic stem cell transplant: Report of a rare case

Chronic myelomonocytic leukemia is a clonal chronic hematopoietic disorder that has been classified under the category of Myelodysplastic syndrome/Myeloproliferative neoplasms (MDS/MPN). CMML has high chances of transforming to acute leukemia, however isolated CNS relapse in CMML has never been reported in literature. We report an extremely rare case of a 47 yearold female diagnosed to have CMML- 2 in remission, who developed an isolated central nervous system relapse after matched related allogeneic hematopoietic stem cell transplantation. To our knowledge this is the first report of isolated CNS relapse in CMML post allogeneic stem cell transplant.

Megakaryocytes, erythropoietic and granulopoietic cells express CAL2 antibody in myeloproliferative neoplasms carrying CALR gene mutations

Testing for the CALR mutation is included in the updated WHO criteria for essential thrombocythaemia (ET) and primary myelofibrosis (PMF). We report on the application of the CAL2 monoclonal antibody, raised against the mutated CALR gene to myeloid cases. The immunostain was used on 116 acute myeloid leukaemias (AML) and 66 myeloproliferative neoplasms (MPN) or myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN). None of AML cases was stained by the CAL2 antibody, while 20/66 MPNs and MDS/MPNs appeared positive. Fourteen of the latter cases were studied by molecular techniques, and all showed aberrations of the CALR gene. In addition, CAL2 positivity was found in some small‐sized elements besides megakaryocytes. By double staining, these elements corresponded to small megakaryocytes as well as both erythroid and myeloid precursors. This finding suggests possible occurrence of CALR gene abnormalities in a stem cell.

Genetic and epigenetic factors interacting with clonal hematopoiesis resulting in chronic myelomonocytic leukemia.

Since 2016, the WHO has recognized the significant phenotypic heterogeneity of chronic myelomonocytic leukemia (CMML) as a myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap disease. Although sharing many somatic mutations with MDS and MPN, the purpose of this review is to put recent biological findings of CMML in the context of evolutionary theory, highlighting it as a distinct evolutionary trajectory occurring in the context of clonal hematopoiesis. Clonal hematopoiesis of indeterminate potential (CHIP), with a mutational spectrum and prevalence correlated with age, has been defined. Enriched in DNMT3A, TET2, and ASXL1 mutations, clonal evolution can progress into various evolutionary trajectories including CMML. Impact of founder mutations (primarily TET2) on increased hematopoietic stem cell fitness has been well characterized. Epistatic interactions between mutations and epigenetic events have been explored, both in CMML and its pediatric counterpart juvenile myelomonocytic leukemia, including CMML transformation to acute myeloid leukemia. Together, these findings have contributed significantly toward CMML evolutionary dynamics. Despite relatively few 'driver' mutations in CMML, evolutionary development of chronic leukemia remains incompletely understood. Recent studies have shed light on the importance of studying epigenetic consequences of mutations and epistasis between key mutations to better understand clonal architecture and evolutionary dynamics.

Renal Infarction and Pulmonary Embolism in Patient with Myelodysplastic/Myeloproliferative Neoplasm Unclassifiable

The myelodysplastic syndrome-myeloproliferative neoplasms (MDS/MPNs) are defined by a group of heterogeneous hematological malignancies resulting from stem cell−driven clonal growth of pathological hematopoietic progenitors and ineffective hematopoiesis, they are characterized concomitant myelodysplastic and myeloproliferative signs. Myelodysplastic/myeloproliferative disorders have been considered to have a higher risk of thrombus formation.We report a rare case about a 64 years old Moroccan woman, experienced renal infarction (RI) associated with pulmonary embolism as a complication of a myelodysplastic/myeloproliferative disorder.The patient complained of acute-onset severe left flank pain, a contrast-enhanced computed tomography (CT) of the chest and abdomen revealed RI by a large wedge-shaped defect in the right kidney with pulmonary embolism.Biological exam showed deep anemia, the bone marrow aspiration found myelodysplasia.the bone biopsy showed signs of myeloproliferatif disease. The karyotype was normal, BCR-ABL, JAK2, CALR mutations were absents, and MPL mutation was positive. The International Prognostic Scoring System (IPSS-R) was 0, and the patient was included to the low risk group.Anticoagulation therapy was initiated with heparin to treat RI and pulmonary embolism. Three months later, pulmonary embolism had resolved without the appearance of additional peripheral infarction.This case emphasizes the need to consider myelodysplastic/myeloproliferative disorders as a cause of infraction renal and pulmonary embolism.

Phenotypic Correlates and Prognostic Outcomes of TET2 Mutations in Myelodysplastic Syndrome/Myeloproliferative Neoplasm Overlap Syndromes: A Comprehensive Study of 504 Patients

Introduction: Myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndromes consist of 5 distinct WHO-defined entities; namely chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia, BCR/ABL1- (aCML), juvenile myelomonocytic leukemia (JMML), MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), and MDS/MPN, unclassifiable (MDS/MPN-U) (Arber et al., Blood 2016). With the notable exception of JMML, a bona fide RASopathy, the other entities are characterized by clinical heterogeneity and molecular diversity. Loss of function TET2 mutations (TET2MT) are common in myeloid neoplasms, especially CMML (60%), and are known leukemogenic drivers. We carried out this study to assess the TET2 mutational landscape and phenotypic correlates in patients with MDS/MPN overlap syndromes. Methods: After approval by the institutional review board, adult patients with WHO defined MDS/MPN overlap syndromes were included; with the exception of JMML. The BM morphology, cytogenetics and 2016, WHO-diagnoses were retrospectively reviewed and all patients underwent targeted next generation sequencing for 29 myeloid-relevant genes, obtained on BM mononuclear cells, at diagnosis, or at first referral, by previously described methods (Patnaik et al., BCJ 2016). Results: Five hundred and four patients were included in the study; including 387 (77%) with CMML, 48 (10%) with MDS/MPN-RS-T, 17 (3%) with aCML and 52 (10%) with MDS/MPN-U. The median age at diagnosis was 71 (range, 18-99) years, and 333 (66%) were male. TET2MT were seen in 212 (42%) patients, with the frequency of other mutations being: ASXL1 45%, SRSF2 40%, NRAS 15%, SF3B1 13%, CBL, RUNX1 and SETBP1 12% each, and JAK2 V617F 11% (Figure B). Among the MDS/MPN overlap syndromes, TET2 was more frequently mutated in CMML (49%) and aCML (47%) compared to MDS/MPN-RS-T (10%) and MDS/MPN-U (15%). The prevalence of patients with TET2MT increased with age, a finding consistent across all MDS/MPN subtypes (Figure C). Overall, 341 TET2MT were identified in 212 patients (mean 1.6 variants/patient, range 0-5): 120 (24%) had >1 TET2MT, while 113 (22%), 5 (1%) and 2 (0.4%) had 2, 3 and 5 mutations, respectively. CMML and aCML patients were more likely to have an age-independent increase in multiple TET2MT (28% and 24%), in comparison to MDS/MPN-RS-T (4%) and MDS/MPN-U (8%). TET2 MT spanned the entire coding sequence and were mostly truncating (78%, Figure A): 59 (17%) were missense, 14 (4%) involved the splice-donor/acceptor sites, 2 (0.5%) were in-frame deletions, 129 (38%) were nonsense, and 137 (40%) were frameshift mutations. Overall, the distribution of TET2MT was superimposable across CMML, aCML, and MDS/MPN-U; the only exception being the absence of splice site mutations in the latter two. One hundred and eighty-seven (55%) TET2MT were secondary to pathogenic single nucleotide variants (SNV), while the remainders were secondary to deletions (25%) and insertions (15%). Transitions comprised the most frequent type of SNV (65%), with the C:G>T:A being the most common (56%). Patients with MDS/MPN overlap syndrome and TET2MT were more likely to have additional gene mutations compared to wild type patients (mean mutation number 3.1 vs 2.1, p<0.0001), with common co-mutations being SRSF2 (51%), ASXL1 (42%), and CBL (17%). The median overall survival (OS) of the entire cohort was 29 (range, 0-170) months; 29 months for CMML, 63 months for MDS/MPN-RS-T, 14 months for aCML, and 25 months for MDS/MPN-U. On univariate analysis, OS was superior in CMML patients with TET2MT (35 months) compared to wild type cases (21 months, p<0.0001, Figure D), and in CMML patients with >1 TET2MT (41 months) in comparison to wild type (21 months, p<0.0001) and single TET2MT (29 months, p=0.0476) cases (Figure E). These observations were not seen in patients with aCML, MDS/MPN-RS-T, and MDS/MPN-U. Conclusion: Our study demonstrates that TET2MT are among the most frequent mutations in patients with MDS/MPN overlap syndromes (42%), especially CMML (49%), with an age-dependent increase in the frequency and number of TET2MT. Mutations in TET2 were found to span the entire coding sequence, with truncating mutations being more common (78%). Importantly, in CMML, TET2MT, including number of TET2MT, were associated with favorable survival outcomes. Figure Disclosures Al-Kali: Astex Pharmaceuticals, Inc.: Research Funding. Patnaik:Stem Line Pharmaceuticals.: Membership on an entity's Board of Directors or advisory committees.

A Phase II Trial of Azacitidine (AZA) in Combination with Ruxolitinib (RUX) in Myelodysplastic Syndrome/Myeloproliferative Neoplasms (MDS/MPNs)

A Phase II Trial of Azacitidine (AZA) in Combination with Ruxolitinib (RUX) in Myelodysplastic Syndrome/Myeloproliferative Neoplasms (MDS/MPNs)

Myelodysplastic Syndrome/Myeloproliferative Neoplasm (MDS/MPN) Overlap Syndromes: Molecular Pathogenetic Mechanisms and Their Implications.

The MDS/MPN overlap syndromes are recently evolved entities that have been quite difficult to define since their discovery. They have overlapping features with other myeloid neoplasms such as MDS and MPN, which further complicates the task of their diagnosis. The unravelling of their molecular pathogenesis by recent diagnostic innovations was of paramount significance in understanding the mechanism of these syndromes. The identification of the major genetic pathways implicated in their pathogenesis not only will help in their diagnosis, but also will enable development of targeted molecular therapy as well as prognostic markers. This review discus the basic molecular aberrations in MDS/MPN overlap syndromes and their possible future implications.

Combined Pharmacological Inhibition of Bruton's Tyrosine Kinase (BTK) and Phosphoinositide 3-Kinase (PI3K) p110δ Rescues Monocytosis, Thrombocytopenia, and Splenomegaly in a Genetic Mouse Model for JMML

Juvenile myelomonocytic leukemia (JMML) is an aggressive childhood myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN). It has no effective treatments and the only treatment that prolongs survival is allogeneic hematopoietic stem cell transplant (HSCT). However, even with this aggressive intervention, approximately 50% of patients relapse with JMML within five years. The most commonly mutated gene in JMML patients is PTPN11, which encodes for the non-receptor protein tyrosine phosphatase SHP2. Gain-of-function (GOF) mutations in SHP2 lead to hyperactive RAS signaling and PTPN11 is recognized as a well-established oncogene in various leukemia's. Our lab has shown that p110δ, the hematopoietic-specific catalytic subunit of phosphoinositide 3-kinase (PI3K), plays an important role downstream of SHP2-signaling. Recently, we have shown that in vivo treatment with a specific pharmacologic p110δ inhibitor significantly prolongs the overall survival and reduces the splenomegaly seen in GOF Shp2-expressing mice. Having observed the effectiveness of PI3K p110δ inhibition in correcting the mutant Shp2-induced leukemia phenotype in vitro and in prolonging survival of mice in vivo, we next explored signaling molecules with which p110δ may be interacting to promote the aberrant Shp2 signaling in myeloid cells. In recent years, a key player in B cell receptor (BCR) signaling, Bruton's tyrosine kinase (BTK), has come under intense study in the field of lymphocytic leukemia and lymphoma research. Ibrutinib, a small molecule inhibitor targeting BTK, has proven to be very effective and has received FDA-approval for the treatment of a variety of B cell malignancies. Although research on BTK up to this point has focused on B cell malignancies, BTK is also highly expressed in myeloid cells and mice lacking BTK are defective in many myeloid cell functions. Thus, it is possible that BTK signaling may also play an important role in myeloid malignancies, such as JMML. Given the collaboration of BTK and p110δ in BCR signaling, the key role of p110δ in GOF Shp2-induced leukemia, and the high expression of BTK in myeloid cells, we hypothesized that BTK and p110δ function cooperatively in GOF Shp2-expressing myeloid cells to promote MPN. To test this hypothesis, we examined the potential collaboration of GM-CSF-stimulated BTK and p110δ in GOF Shp2-expressing myeloid cells and tested the inhibitor combination in vivo. We show that BTK cooperates with p110δ to promote GOF Shp2-induced leukemia. We show a role for B cell adaptor for PI3K (BCAP) in BTK upregulation of PI3K activity. In mutant Shp2 macrophages, BCAP phosphorylation is increased specifically in the larger isoforms regulating PI3K activation, and BTK inhibition results in a dose-dependent reduction in this phosphorylation. Our findings show that the MPN caused by GOF Shp2 is due to cooperative signaling between p110δ and BTK, which forms a positive feedback loop with BCAP, thus leading to more Akt/Erk hyperphosphorylation and hyperproliferation in response to GM-CSF.Given these in vitro observations, we treated GOF Shp2 bearing mice with a combination of a PI3K p110δ-specific inhibitor and, a BTK-specific inhibitor, or single agents alone and performed hematopoietic analysis. The combination treatment scheme completely rescued monocytosis and uniquely ameliorated thrombocytopenia compared to single agent treatment of diseased mice. In addition, splenomegaly was also completely rescued in all three treatment groups compared to vehicle. Detailed flow cytometric analysis of bone marrow hematopoietic stem and progenitor cell populations revealed significant repression of LSK, HPC1 and granulocyte macrophage progenitors (GMPs) with a concomitant increase in the megakaryocyte precursors (MKPs) in drug combination treated mice vs. other groups. Consistent with these observations, a significant reduction in mature myeloid cells was noted in the spleen and a complete rescue in the production of peripheral blood platelets was observed in the mutant mice treated with a combination of the two drugs. Thus, combination therapy with PI3K p110δ- and BTK-specific inhibitors profoundly rescues disease state hallmarks of JMML, and may warrant further clinical investigation. DisclosuresNo relevant conflicts of interest to declare.

Inflammatory disorders associated with trisomy 8-myelodysplastic syndromes: French retrospective case-control study.

We report cases of myelodysplastic syndrome/myeloproliferative neoplasms (MDS/MPN) with trisomy 8 associated with inflammatory and autoimmune diseases (IADs). Data for 21 patients with trisomy 8-MDS/MPN and IADs were analyzed and compared to 103 patients with trisomy 8-MDS/MPN without IADs. The median age of MDS/MPN patients with IADs was 67 [59-80]. The IADs were Behçet's-like disease in 11 (52%) patients, inflammatory arthritis in 4 (19%) and Sjögren's syndrome, autoimmune hemolytic anemia, aseptic abscess, periarteritis nodosa, Sweet's syndrome and unclassified vasculitis in one patient each. Overall, 17/21 (81%) patients with IADs received treatment (88% with steroids), with complete and partial response in 7/17 (35%) and 8/17 (47%), respectively. The effect of MDS treatment on IADs could be assessed in seven patients receiving azacytidine: five achieved remission and two partial response. As compared with the 103 trisomy 8-MDS/MPN cases without IADs, those with IADs were more often non-European (P=0.005) and had poor karyotype (P<0.001). We found no difference in overall survival or acute myeloid leukemia progression between trisomy 8-associated MDS/MPN with and without IADs. The spectrum of IADs associated with trisomy 8-positive MDS/MPN is dominated by Behçet's-like disease. Steroid therapy is effective, but mostly sparing therapies are necessary. Azacytidine could be an effective alternative.

The Challenge of Treating Myelodysplastic Syndromes/Myeloproliferative Neoplasms.

Myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) comprise a spectrum of myeloid disorders with both dysplastic and proliferative features, arising from hematopoietic stem cells. MDS/MPN are neither MDS nor MPN but a distinct World Health Organization-defined subclassification of diseases that, by definition, do not arise from a pre-existing MDS or MPN, inherently creating diagnostic and therapeutic challenges. Appropriately recognizing and classifying MDS/MPN is paramount for appropriately formulating treatment strategies and accurate prognostication. Highlighting the unique molecular, morphologic, and clinical characteristics among the subclassifications of MDS/MPN can assist in the appropriate diagnosis and aid in choice of therapeutic strategies. We describe the challenges of the appropriate diagnosis and treatment of MDS/MPN.

Turning the tide in myelodysplastic/myeloproliferative neoplasms.

Myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN) are aggressive myeloid malignancies recognized as a distinct category owing to their unique combination of dysplastic and proliferative features. Although current classification schemes still emphasize morphology and exclusionary criteria, disease-defining somatic mutations and/or germline predisposition alleles are increasingly incorporated into diagnostic algorithms. The developing picture suggests that phenotypes are driven mostly by epigenetic mechanisms that reflect a complex interplay between genotype, physiological processes such as ageing and interactions between malignant haematopoietic cells and the stromal microenvironment of the bone marrow. Despite the rapid accumulation of genetic knowledge, therapies have remained nonspecific and largely inefficient. In this Review, we discuss the pathogenesis of MDS/MPN, focusing on the relationship between genotype and phenotype and the molecular underpinnings of epigenetic dysregulation. Starting with the limitations of current therapies, we also explore how the available mechanistic data may be harnessed to inform strategies to develop rational and more effective treatments, and which gaps in our knowledge need to be filled to translate biological understanding into clinical progress.

Proactive Consultation by a Clinical Pathologist Prevents Diagnostic Delay in Hematological Malignancies.

Diagnostic difficulties in hematological malignancies may lead to unacceptably prolonged help-seeking to diagnostic interval as well as increased complications and poor outcomes. Proactive consultation by a clinical pathologist (PCCP) may help clinical diagnosis and therapeutic strategy. Hence, the aim of this investigation was to evaluate the effect of PCCP on the help-seeking to diagnostic interval in hematological cancer cases. From January to November, 2015, abnormal results of hematological laboratory testing with added laboratory comment were selectively screened out, and patients with such abnormalities in hematological laboratory testing and accompanied laboratory comment with PCCP were enrolled. A total of 125 aberrant results of hematological laboratory testing were given with accompanied laboratory comments with PCCP and 40.8% (n=51) of these patient-oriented comments had an effect on clinical diagnosis and therapeutic strategy. Twelve of the subjects belonged to newly diagnosed hematological malignancies with the assistance of PCCP, and the help-seeking to diagnostic interval was also shortened from 42 days to 26 days in chronic lymphoid leukemia (CLL), from 83 days to 11 days in multiple myeloma (MM), and from 128 days to 15 days in myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN). During the monitoring interval, neither complication events nor deaths were reported in the study group. It was seemingly that PCCP prevented diagnostic delay in hematological malignancies via shortening the help-seeking to diagnostic interval, particularly in CLL, MM and MDS/MPN cases. PCCP can be considered to play an essential role in prompt establishment of diagnosis in hematological malignancies for those who newly present.

Dysregulation of RUNX1 Plays a Critical Role in the Progression of Myelodysplastic Syndromes

Abstract RUNX1/AML1 mutations have been frequently detected in patients with myeloid neoplasms, especially myelodysplastic syndromes (MDS) and chronic monocytic leukemia (CMML). Although the mutations have been analyzed thoroughly, its expression level has not been investigated. Therefore, we attempt to clarify the expression of RUNX1 in the pathogenesis of myeloid neoplasms. The study was approved by the institutional review board and patients gave written informed consent for the study, according to the Declaration of Helsinki. Several isoforms of RUNX1 mRNA are known and we analyzed RUNX1a (including exon 7a which has stop codon) and RUNX1b (skipping exon 7a and including exon 7b and 8). Expression levels of full length isoform (RUNX1b) and short isoform (RUNX1a which has a dominant negative effect on RUNX1b) in CD34+ cells from patients with myeloid neoplasms were examined. A part of patients with MDS or myelodysplastic syndrome / myeloproliferative neoplasms (MDS/MPN) including CMML showed RUNX1a overexpression. Average of relative RUNX1a expression level in MDS patients (n=34) and MDS/MPN patients (n=20) was 7.4-fold and 8.6-fold of the level in normal bone marrow (BM), respectively, whereas most of these patients showed almost same or slight increase of expression level of RUNX1b compared with normal BM. Interestingly, some patients showed high expression of RUNX1a and repression of RUNX1b. In both disease categories, patients with excess blasts displayed a significantly higher expression level of RUNX1a compared with normal BM and patients without excess blasts. During the disease progression in a single patient with MDS or MDS/MPN, the expression of RUNX1a became higher, while azacitidine treatment reduced RUNX1a expression. Genomic mutations of RUNX1 were also examined. RUNX1 mutations were detected in 16% of MDS and 35% of MDS/MPN. Surprisingly, a part of patients had both RUNX1 gene mutation and RUNX1a overexpression, and they showed rapid progression of disease. To evaluate the effects of RUNX1a overexpression, RUNX1a was transduced into CD34+ cells from MDS patients with low expression level of RUNX1a. RUNX1a-transduction resulted in cell proliferation on MS5 stromal cells. These results indicate that overexpression of RUNX1a may add growth advantage to CD34+ cells in patients with MDS or MDS/MPN. We next analyzed the mechanism of RUNX1a overexpression. Gene mutations affecting exon recognition were examined in the patients. Splicing factor mutations, SRSF2 and U2AF1, were detected frequently in MDS (15%) and MDS/MPN (50%). Patients with splicing factor mutations showed higher RUNX1a expression than patients without the mutations. To confirm that the splicing factor mutations affect the expression of RUNX1a, we performed enforced expression of SRSF2 p.P95H mutant using pMYs.IRES.EGFP retrovirus vector in a MDS-derived cell line, TF-1. After a single cell sorting, independent 13 expanding clones were analyzed. Most of the clones demonstrated higher expression of RUNX1a than mock cells, whereas RUNX1b expression was reduced in all clones. Increase of RUNX1a expression in SRSF2 mutant-transduced TF-1 cells was also confirmed by Western blot. Moreover, the clones with higher GFP intensity showed higher expression level of RUNX1a, suggesting that SRSF2 p.P95H expression level may affect the expression level of RUNX1a. Furthermore, SRSF2 mutant-transduced TF-1 cells showed phenotypic changes of higher CD11b and CD14 than mock TF-1 cells, suggesting that SRSF2 mutant may induce monocytic differentiation via RUNX1a overexpression. Gene mutations of RUNX1 in intron 6 and exon 7a were also analyzed. A 5' splice site change just after exon 6 was detected in a CMML patient with RUNX1a overexpression, which may be another mechanism of RUNX1a overexpression. Mutations of exon 7a or changes in 3' splice site just before exon 7a have not been detected yet. In conclusion, our data suggest that overexpression of RUNX1a may play a critical role in the progression of MDS and MDS/MPN, in addition to RUNX1 mutations. Splicing factor mutations are suspected to contribute to the mechanism of the dysregulation of RUNX1. Disclosures No relevant conflicts of interest to declare.

Inhibition of Akt Signaling Alleviates MDS/MPN Driven By KrasD12 or Nf1 Loss

Juvenile and chronic myelomonocytic leukemias (JMML and CMML) are aggressive myeloid malignancies categorized as myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN). Chemotherapy has little benefit for MDS/MPN patients, and new therapies are needed. We have used mouse models investigate the potential of signal transduction inhibitors in MDS/MPN, as JMML and CMML are associated with mutations in NRAS, KRAS, PTPN11, CBL, or NF1 that activate Ras signaling. Conditional Mx1-Cre, KrasLSL-D12 (designated KrasD12) mice develop an aggressive and fully penetrant MDS/MPN characterized by leukocytosis, splenomegaly, anemia, and death by 10-16 weeks of age. Mx1-Cre, Nf1flox/- mice (hereafter Nf1Δ/-) undergo conditional loss of Nf1. These mice also develop MDS/MPN, but the disease is more indolent. We and others have investigated inhibition of effector networks downstream of Ras, such as the Raf/MEK/ERK (MAPK) and phosphotidylinositol-3 kinase (PI3K)/Akt pathways. We previously showed that the MEK inhibitor PD0325901 induced sustained hematologic improvement in both KrasD12 and Nf1Δ/- mice. We also have reported that the class I PI3K inhibitor GDC-0941 improves hematologic function and prolongs survival in KrasD12 mice. However, GDC-0941 and other PI3K inhibitors attenuate both PI3K/Akt and Raf/MEK/ERK pathways due to effects of PI3K upstream of Ras. Therefore, the benefit from GDC-0941 could have been due to its modulation of Raf/MEK/ERK signaling. Here, we specifically test the importance of Akt signaling in MDS/MPN in KrasD12 and Nf1 mouse models using the allosteric inhibitor MK-2206. This compound binds to the interface of the PH and kinase domains of Akt1, Akt2, and Akt3, and does not inhibit any of 250 other kinases at 1 µM. MK-2206 induced substantial improvement in both KrasD12 and Nf1Δ/- mice. Mice treated with MK-2206 had pronounced reduction in leukocytosis, reticulocytosis and splenomegaly, increased hemoglobin concentration, and prolonged survival. MK-2206 had no hematologic effects in control WT mice, indicating some selectivity against aberrant hematopoiesis. Importantly, MK-2206 inhibited Akt but not Raf/MEK/ERK or Jak/STAT signaling. This demonstrates that canonical PI3K/Akt signaling plays an important role in Ras-driven MDS/MPN. Furthermore, combined inhibition of MEK and Akt with PD0325901+MK-2206 yielded a greater improvement in splenomegaly than either agent alone in both KrasD12 and Nf1Δ/- models. Akt has multiple effectors relevant to hematopoiesis and leukemia. Of these, mTOR is of particular interest for targeted cancer therapy. Therefore, we tested the response of KrasD12 mice to rapamycin, a partial inhibitor of mTOR with preferential activity against the mTORC1 complex. KrasD12 mice demonstrated variable responses to rapamycin, with approximately half undergoing a complete and durable hematologic response and the remainder having no response. Together, these studies further implicate PI3K/Akt signaling as a pathogenic effector downstream of Ras in MDS/MPN and support the idea that inhibitors targeting this pathway may have a role in treatment of JMML or CMML. DisclosuresNo relevant conflicts of interest to declare.

Broad Activity of Apto-253 in AML and Other Hematologic Malignancies Correlates with KLF4 Expression Level

Introduction: Aberrant expression of the homeodomain transcription factor CDX2 has recently been reported in a large proportion of AML cases. One consequence of CDX2 deregulation appears to be repressed expression of the transcription factor KLF4. Repression of KLF4 was shown to be critical for CDX2-mediated tumorigenesis, and forced genetic de-repression of KLF4 led to apoptosis of AML cells. APTO-253 is a novel small molecule that induces the expression of KLF4 and is cytotoxic to AML cell lines at low-nanomolar concentrations. We evaluated the activity of APTO-253 against a broad panel of primary specimens from patients with acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and myelodysplastic syndromes/myeloproliferative neoplasms (MDS/MPN). APTO-253 was tested both as a single agent and in combinations with 2 other emerging targeted therapies, the BET bromodomain inhibitor JQ1 and the FLT3 inhibitor quizartinib.Methods: We used an ex vivo drug sensitivity assay to determine the activity of APTO-253, JQ1, and quizartinib across increasing concentrations of each agent up to 10 μM. Combinations were tested at fixed, equimolar ratios over the same concentration range. After a 3-day ex vivo culture, cell viability was assessed using a colorimetric tetrazolium-based MTS assay, and IC50 values were calculated. RNA-Seq was performed on AML specimens to permit investigation of correlations of drug sensitivity with gene expression levels.Results: We evaluated specimens from 177 patients with a variety of hematologic malignancy diagnoses (80 AML, 72 CLL, 25 MDS/MPN). The highest frequency of APTO-253 sensitivity occurred in AML, with 43/80 (54%) samples exhibiting an IC50 <1 μM. At this cutoff, 25/72 (35%) CLL samples and 3/25 (12%) MDS/MPN samples were sensitive to APTO-253. The average expression of KLF4 mRNA was 2-fold lower among AML samples with an IC50 <1 µM compared to those with IC50 >1 µM (p=0.07). Approximately 65% (56/87) of cases tested with a combination of APTO-253 and JQ1 showed the combination IC50 to be at least 2-fold lower than the IC50 of either agent alone. This enhanced efficacy of APTO-253 with JQ1 was observed across all 3 hematologic malignancies tested, whereas quizartinib enhancement of APTO-253 sensitivity was confined to AML (14/38, or 37% showed reduced IC50).Conclusions: These results support the potential of KLF4 as an important and frequently dysregulated master transcription factor in AML and suggest that the KLF4 inducer APTO-253 is effective at killing tumor cells in a majority of AML samples. The data also indicate activity of APTO-253 in other hematologic malignancies, namely CLL. Expression level of KLF4 may be one component of a biomarker for prediction of APTO-253 efficacy; a more extensive global gene expression signature analysis is under way. Finally, these data have identified prominent interaction of APTO-253 with the BET bromodomain inhibitor JQ1, as well as AML-restricted interaction of APTO-253 with the FLT3 inhibitor quizartinib, suggesting these classes of drugs as potential combination partners for APTO-253. DisclosuresRice:Aptose Biosciences: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Howell:Aptose Biosciences: Consultancy, Equity Ownership; Angstrom: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Abeoda: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; InhibRx: Equity Ownership. Vellanki:Aptose Biosciences: Employment, Equity Ownership. Druker:Oncotide Pharmaceuticals: Research Funding; Sage Bionetworks: Research Funding; Fred Hutchinson Cancer Research Center: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis Pharmaceuticals: Research Funding; Henry Stewart Talks: Patents & Royalties; McGraw Hill: Patents & Royalties; Leukemia & Lymphoma Society: Membership on an entity's Board of Directors or advisory committees, Research Funding; Blueprint Medicines: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Oregon Health & Science University: Patents & Royalties; MolecularMD: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Consultancy, Membership on an entity's Board of Directors or advisory committees; ARIAD: Research Funding; AstraZeneca: Consultancy; Aptose Therapeutics, Inc (formerly Lorus): Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; CTI Biosciences: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Millipore: Patents & Royalties; Roche TCRC, Inc.: Consultancy, Membership on an entity's Board of Directors or advisory committees; Cylene Pharmaceuticals: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Tyner:Incyte: Research Funding; Janssen Pharmaceuticals: Research Funding; Constellation Pharmaceuticals: Research Funding; Array Biopharma: Research Funding; Aptose Biosciences: Research Funding.

Impact of TET2, SRSF2, ASXL1 and SETBP1 mutations on survival of patients with chronic myelomonocytic leukemia.

BackgroundChronic myelomonocytic leukemia (CMML) is a myeloid neoplasm classified in the myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) category. Molecular abnormalities are reported in about 90 % of patients with CMML. ASXL1 and SETBP1 mutations, but not TET2 or SFRS2 mutations are reported to be associated with prognosis.MethodsWe studied frequency of TET2, SRSF2, ASXL1 and SETBP1 mutations in 145 patients with CMML using Sanger sequencing, and determined the prognostic factors for OS. We also identified the predictive value of ASXL1 mutations (frameshift and nonsense mutations) through comparing the Mayo Prognostic Model with the Mayo Molecular Model.ResultsForty-seven (32 %) had a mutation in TET2, 42 (29 %), a mutation in SRSF2, 65 (45 %), a mutation (nonsense and frame-shift) in ASXL1 and 26 (18 %), a mutation in SETBP1. Significant variables in multivariable analysis of survival included ASXL1 (HR = 1.99 [1.20–3.28]; P = 0.007), hemoglobin <100 g/L (HR = 2.42 [1.40–4.19]; P = 0.002) and blood immature myeloid cells (IMCs) (HR = 2.08 [1.25–3.46]; P = 0.005). When our patients were analyzed using the Mayo Prognostic Model median OS were not reached, 26 months and 15 months (P = 0.014). An analysis using the Mayo Molecular Model identified 4 cohorts with median OS of not reached, 70 months, 26 months and 11 months (P < 0.001). Data fitting using our patients suggest the Molecular Mayo Model has significantly higher survival predictive power compared with Mayo Prognostic Model (P < 0.001, −2 log-likelihood ratios of 538.070 and 552.260).ConclusionsThere were high frequencies of mutations in TET2, SRSF2, ASXL1 and SETBP1 in patients with CMML. With the addition of ASXL1 frameshift and nonsense mutations, the Mayo Molecular Model fitted better than Mayo Prognostic Model of our patients.

Feedback Through Dusp6 Modulates Ineffective Erythropoiesis Caused By Mutant Kras

Somatic mutations that activate Ras signaling are common in hematologic malignancies. They are particularly associated with juvenile and chronic myelomonocytic leukemias, which are classified as ‘overlap' myelodysplastic syndromes / myeloproliferative neoplasms (MDS/MPN). These diseases are characterized by myelomonocytic proliferation and dysplasia leading to anemia and thrombocytopenia. We have previously shown that conditional expression of KrasG12D in mice models MDS/MPN, producing a fatal disease with increased granulocyte/macrophage (G/M) progenitors and a reduction in the megakaryocyte/erythroid (Meg/E) lineage. Despite intensive study of Ras signaling, the mechanisms by which oncogenic Ras regulates cell fate decisions in hematopoiesis remain unclear; better understanding of these processes may allow development of novel therapies for MDS/MPN. We found that mRNA and protein levels of dual specificity phosphatase-6 (Dusp6), a negative regulator of MAPK signaling, is elevated in the bone marrow of KrasG12D mice. This suggested that a negative feedback loop generated by Dusp6 might regulate the proliferation and differentiation of hematopoietic progenitors in MDS/MPN. To test this hypothesis, we conditionally expressed KrasG12D from its endogenous locus in the bone marrow of wild type and Dusp6 knockout mice. Interestingly, many characteristics of MDS/MPN were more severe in Dusp6-/-; KrasG12D mice. For example, we observed significantly lower hemoglobin levels in 3-4 week old Dusp6-/-; KrasG12D mice (8.35g/dL, n=4) compared to Dusp6+/+; KrasG12D mice (11.7g/dL, n=10). Moreover, the peripheral blood of Dusp6+/+; KrasG12D mice contained approximately 13% of reticulocytes (n=12), whereas Dusp6-/-; KrasG12D mice had nearly 36% reticulocytes (n=4) in the peripheral blood. Furthermore, we observed acanthocytes, poikilocytes and other structural abnormalities in the red blood cells from Dusp6-/-; KrasG12D mice and not in mice wild type for Dusp6. Thus, Dusp6 loss accelerates the onset of anemia caused by KrasG12D, which suggests an exacerbation of the erythroid differentiation defect. We did not observe any significant differences in white blood count or spleen size attributable to Dusp6 genotype. Differentiation of hematopoietic progenitors was assessed in the bone marrow by flow cytometry. The frequency of pre-Meg/E progenitors (Lin-Sca1-Kit+CD34+FcgR-CD150+CD105-) from Dusp6-/-; KrasG12D mice was reduced by approximately 50% when compared to Dusp6+/+; KrasG12D mice. Consistent with this result, Dusp6-/-; KrasG12D mice possessed a significantly greater percentage of immature red blood cells (proerythroblasts; CD71hi Ter119+) and fewer mature red blood cells (orthochromatic erythroblasts; CD71+ Ter119+) than bone marrow cells from Dusp6+/+; KrasG12D mice. By contrast, Dusp6 expression does not have an effect on the frequency of pre-G/M cells (Lin-Sca1-Kit+CD34+FcgR-CD150-CD105-), which remains unchanged between Dusp6+/+; KrasG12D and Dusp6-/-; KrasG12D mice. Together, these findings demonstrate that negative feedback through Dusp6 functions to maintain erythropoiesis the context of oncogenic Ras signaling. Futher, these data strengthen the association between excessive MAPK activity and dyserythropoiesis, and further support development of inhibitors of MEK and/or ERK to treat MDS/MPN. Disclosures:No relevant conflicts of interest to declare.