[Show abstract][Hide abstract] ABSTRACT: Background
The presence of somatic mutations in splicing factor 3b subunit 1 (SF3B1) in patients with Myelodysplastic syndromes with ring sideroblasts (MDS-RS) highlights the importance of the RNA-splicing machinery in MDS. We previously reported the presence of bone marrow (BM) RS in Sf3b1 heterozygous (Sf3b1 +/¿) mice which are rarely found in mouse models of MDS. Sf3b1 +/¿ mice were originally engineered to study the interaction between polycomb genes and other proteins.Methods
We used routine blood tests and histopathologic analysis of BM, spleen, and liver to evaluate the hematologic and morphologic characteristics of Sf3b1 +/¿ mice in the context of MDS by comparing the long term follow-up (15 months) of Sf3b1 +/¿ and Sf3b1 +/+ mice. We then performed a comprehensive RNA-sequencing analysis to evaluate the transcriptome of BM cells from Sf3b1 +/¿ and Sf3b1 +/+ mice.Results Sf3b1 +/¿ exhibited macrocytic anemia (MCV: 49.5¿±¿1.6 vs 47.2¿±¿1.4; Hgb: 5.5¿±¿1.7 vs 7.2¿±¿1.0) and thrombocytosis (PLTs: 911.4¿±¿212.1 vs 878.4¿±¿240.9) compared to Sf3b1 +/+ mice. BM analysis showed dyserythropoiesis and occasional RS in Sf3b1 +/¿ mice. The splenic architecture showed increased megakaryocytes with hyperchromatic nuclei, and evidence of extramedullary hematopoiesis. RNA-sequencing showed higher expression of a gene set containing Jak2 in Sf3b1 +/¿ compared to Sf3b1 +/+.Conclusions
Our study indicates that Sf3b1 +/¿ mice manifest features of low risk MDS-RS and may be relevant for preclinical therapeutic studies.
Journal of hematology & oncology. 12/2014; 7(1):89.
[Show abstract][Hide abstract] ABSTRACT: Background: The myelodysplastic sydromes (MDS) are a heterogeneous group of hematopoietic disorders which have poor overall survival. As its incidence in the general population is only 4.6 out of 100,000, there is a paucity of epidemiological studies on the disorders. We combined three data sets from Pennsylvania, Ohio and New York to study determinants of outcome.
Methods: De-identified patient and clinical data for 1192 incident cases of MDS from three sites were collected non-concurrently, from 1990-2010. All patients were followed from the date of diagnosis to transformation to Acute Myeloid Leukemia (AML), death, or end of the study period (2010). The median of the population baseline blood parameters was used to create cut offs for analyses for hemoglobin levels, neutrophil count, and platelet count. Clinical cutoff values were also utilized. Descriptive and survival analyses were performed.
Results: The study population was 90.5% White, 60.6% male, and ever smokers in 57.8% of cases. Mean age at diagnosis was 68 years. Males were significantly more likely to be ever smokers than females (p<.0001); a significantly higher proportion of non-White patients was observed among males compared with females. Factors significantly associated with survival at multivariate analysis were being female [HR adj: 0.79 (95% CI: 0.66-0.95)], and having a neutrophil count > 1.8 x 109/L, the median value for this sample [HR adj: 0.75 (0.6-0.93)].
Conclusions: Among MDS patients, females and patients with higher neutrophil counts have better survival than males or patients with lower neutrophil counts, respectively, and this may reflect differences in the biology of the disease, or in environmental exposure.
142nd APHA Annual Meeting and Exposition 2014; 11/2014
[Show abstract][Hide abstract] ABSTRACT: Purpose: New therapies are urgently needed for patients with acute myeloid leukemia (AML). The novel NEDDylation inhibitor MLN4924 (pevonedistat) has demonstrated significant preclinical anti-leukemic activity and preliminary efficacy in patients with AML in a Phase I trial. Based on its anti-myeloid and DNA-damaging properties, we investigated the ability of MLN4924 to augment conventional cytarabine (ara-C) therapy. Experimental Design: The effects of MLN4924/ara-C on viability, clonogenic survival, apoptosis, DNA damage and relevant pharmacodynamic targets were determined. The efficacy and pharmacodynamics of MLN4924/ara-C were assessed in an AML xenograft model. Results: Co-treatment of AML cell lines and primary patient specimens with MLN4924 and ara-C led to diminished clonogenic survival, increased apoptosis, and synergistic levels of DNA damage. RNA interference demonstrated that stabilization of CDT-1, an event previously shown to mediate the DNA damaging effects of MLN4924, was not a key regulator of sensitivity to the MLN4924/ara-C combination. Global metabolic profiling revealed that MLN4924 disrupts nucleotide metabolism and depletes intracellular nucleotide pools in AML cells. Subsequent experiments showed that MLN4924 promoted increased incorporation of ara-C into the DNA of AML cells. This effect as well as the therapeutic benefit of the MLN4924/ara-C combination were antagonized by supplementation with the nucleotide building block ribose. Co-administration of MLN4924 and ara-C to mice bearing FLT3-ITD+ AML xenografts stably inhibited disease progression and increased DNA damage in vivo. Conclusions: Our findings provide strong rationale for clinical investigation of the MLN4924/ara-C combination and establish a new link between therapeutic inhibition of NEDDylation and alterations in nucleotide metabolism.
Clinical cancer research : an official journal of the American Association for Cancer Research. 11/2014;
[Show abstract][Hide abstract] ABSTRACT: Somatic cohesin mutations have been reported in myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). To account for the morphologic and cytogenetic diversity of these neoplasms, a well-annotated cohort of 1060 patients with myeloid malignancies including MDS (n=386), myeloproliferative neoplasms (MPN, n=55), MDS/MPN (n=169) and AML (n=450) were analyzed for cohesin gene mutational status, gene expression, therapeutic and survival outcomes. Somatic cohesin defects were detected in 12% of patients with myeloid malignancies, while low expression of these genes was present in an additional 15% of patients. Mutations of cohesin genes were mutually exclusive and mostly resulted in predicted loss-of-function. Patients with low cohesin gene expression showed similar expression signatures as those with somatic cohesin mutations. Cross-sectional deep sequencing analysis for clonal hierarchy demonstrated STAG2, SMC3, RAD21 mutations to be ancestral in 18%, 18% and 47% of cases, respectively, and each expanded to clonal dominance concordant with disease transformation. Cohesin mutations were significantly associated with RUNX1, Ras-family oncogenes, BCOR and ASXL1 mutations and were most prevalent in high-risk MDS and secondary AML. Cohesin defects were associated with poor overall survival (27.2 vs. 40 months; p=0.023) especially in STAG2 mutant MDS patients surviving >12 months (median survival 35 vs. 50 months; p=0.017).
[Show abstract][Hide abstract] ABSTRACT: Inhibition of cholesterol synthesis and uptake sensitizes acute myeloid leukaemia (AML) blasts to chemotherapy. A Phase 1 study demonstrated the safety of high dose pravastatin given with idarubicin and cytarabine in patients with AML and also demonstrated an encouraging response rate. The Southwestern Oncology Group (SWOG) trial, SWOG S0919, was a Phase 2 trial evaluating the complete remission (CR) rate in a larger number of patients with relapsed AML treated with idarubicin, cytarabine and pravastatin. This study closed to accrual after meeting the defined criterion for a positive study. Thirty-six patients with a median age of 59 years (range 23–78) were enrolled. The median time from diagnosis to registration was 18 months. Relapse status was first relapse, 17 patients (47%); second relapse, 15 patients (42%); third relapse, two patients (5·5%) and fourth relapse, two patients (5·5%). The response rate was 75% [95% confidence interval: 58–88%; 20 CRs, 7 CR with incomplete count recovery (CRi)], and the median overall survival was 12 months. The P-value comparing 75–30% (the null response rate based on prior SWOG experience) was 3·356 × 10−4. Given the encouraging CR/CRi rate, this regimen should be considered for testing in a prospective randomized trial against best conventional therapy.
British Journal of Haematology 07/2014; · 4.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Low endogenous erythropoietin levels and limited red blood cell transfusion history can predict response to erythropoiesis-stimulating agents in anaemic patients with myelodysplastic syndromes (MDS). The relationship between endogenous thrombopoietin (THPO) levels and platelet response to romiplostim is unknown. Variables including baseline endogenous THPO levels, transfusion needs, and platelet response were analysed in a randomized trial of 250 thrombocytopenic, lower-risk MDS patients (International Prognostic Scoring System low/intermediate-1). A predictive scoring system was developed based on log–likelihood ratios and logistic coefficients. Patients with HI–P (haematological improvement – platelets) responses had lower mean baseline THPO levels (P = 0·0497) and were more likely to have <6 platelet units transfused in the past year (P = 0·0027), as did patients with platelet responses ≥50% of weeks on romiplostim (P = 0·001 and P = 0·0037, respectively). A model for predicting response to romiplostim was developed and validated in a separate MDS cohort (N = 72). Patients in low-, intermediate-, and high-response groups had response rates of 17·4%, 29·6%, and 50·7%, respectively, for HI-P, and 17·4%, 33·8%, and 65·2%, respectively, for ≥50% response. For thrombocytopenic patients with lower-risk MDS, lower baseline THPO levels (<500 pg/ml) and limited platelet transfusion history predicted a greater likelihood of a subsequent platelet response to romiplostim.
British Journal of Haematology 07/2014; · 4.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The introduction of reduced intensity conditioning regimens (RIC) made it possible to offer allogeneic hematopoietic cell transplantation (alloHCT) to older patients with myelodysplastic syndromes (MDS). However, the relative risks and benefits of alloHCT compared to novel non-transplant therapies continue to be the source of considerable uncertainty. We will perform a prospective biologic assignment trial to compare RIC alloHCT to non-transplant therapies based on donor availability. Primary outcome is 3-year overall survival. Secondary outcomes include leukemia-free survival, quality of life, and cost-effectiveness. Four hundred patients will be enrolled over roughly 3 years. Planned subgroup analyses will evaluate key biologic questions, such as the impact of age & response to hypomethylating agents on treatment effects. Findings from this study potentially may set a new standard of care for older MDS patients who are considered candidates for alloHCT.
Biology of blood and marrow transplantation: journal of the American Society for Blood and Marrow Transplantation 06/2014; · 3.15 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: ABSTRACT The AVIDA registry evaluated azacitidine usage and effectiveness in unselected MDS patients in community practice. Treating physicians made all treatment decisions. Hematologic improvement (HI) and transfusion independence (TI) assessments used IWG-2000 criteria. Enrolled were 421 MDS patients (n=228 IPSS lower-risk, n=106 higher-risk, 86 patients unclassified) from 105 U.S. sites. Median follow-up was 7.6 months (range: 0.1-27.6). HI and RBC TI rates were similar regardless of administration route or dosing schedule. Safety and tolerability were consistent with previous reports. The AVIDA registry data support azacitidine effectiveness and safety in lower- or higher-risk MDS patients treated in community practice.
[Show abstract][Hide abstract] ABSTRACT: Over the past decade, our understanding of bone marrow failure has advanced considerably. Marrow failure encompasses multiple overlapping diseases, and there is increasing availability of diagnostic tools to distinguish among the subtypes. Identification of genetic alterations that underlie marrow failure has also greatly expanded, especially for myelodysplastic syndromes. Molecular markers are increasingly used to guide the management of myelodysplasia and may distinguish this diagnosis from other marrow failure disorders. This review summarizes the current state of distinguishing among causes of marrow failure and discusses the potential uses of multiple diagnostic and prognostic indicators in the management of myelodysplastic syndromes and other bone marrow failure disorders.
[Show abstract][Hide abstract] ABSTRACT: Perturbation in iron homeostasis is a hallmark of some hematologic diseases. Abnormal sideroblasts with accumulation of iron in the mitochondria are named ring sideroblasts (RS). RS is a cardinal feature of refractory anemia with RS (RARS) and RARS with marked thrombocytosis (RARS/-T). Mutations in SF3B1, a member of the RNA-splicing are frequent in RARS/-T and defects of this gene were linked to RS formation. Here we showcase the differences in iron architecture of SF3B1 mutant and wild type (WT) RARS/-T and provide new mechanistic insights by which SF3B1 mutations lead to differences in iron. We found higher iron levels in SF3B1 mutant vs WT RARS/-T by transmission electron microscopy/spectroscopy/flow cytometry. SF3B1 mutations led to increased iron without changing the valence as shown by the presence of Fe(2+) in mutant and WT. Reactive-oxygen-species and DNA-damage were not increased in SF3B1 mutant patients. RNA-Seq and RT-PCR showed higher expression of a specific isoform of SLC25A37 in SF3B1 mutant patients, a crucial importer of Fe(2+) into the mitochondria. Our studies suggest that SF3B1 mutations contribute to cellular iron overload in RARS/-T by deregulating SLC25A37.Leukemia accepted article preview online, 23 May 2014; doi:10.1038/leu.2014.170.