Last marrow standing: bone marrow transplantation for acquired bone marrow failure conditions

Aplastic anemia and risk of deep vein thrombosis and pulmonary embolism: A nationwide cohort study

OBJECTIVES

Deep vein thrombosis (DVT) and pulmonary embolism (PE) constitute venous thromboembolism (VTE), which is not fully known in aplastic anemia (AA). Therefore, we investigated the incidence and risk of VTE in AA patients.

METHODS

We conducted a nationwide cohort study to investigate the risk of DVT and PE in patients with AA. We identified patients with newly diagnosed AA as the AA cohort between 2000 and 2010 from the National Health Insurance Research Database (NHIRD). The initial admission date for AA diagnosis was set as the index date. For each patient with AA, 4 patients without a history of AA, frequency matched by sex, age (every 5-y span), and year of index date, were the non-AA cohort. All patients were followed from the index date to the date of DVT or PE diagnosis, withdrawal from the NHIRD, or the end of 2011. Cox models were used to evaluate the risk of developing DVT and PE in the AA cohort.

RESULTS

We included 4001 and 15,998 patients in the AA and non-AA cohorts, respectively, and the overall incidence densities of VTE were significantly higher in the AA cohort than in the non-AA cohort (42.3 vs 10.2 per 10,000person-years). The AA cohort had a 2.56-fold higher risk of VTE (95% confidence interval [CI]=1.81-3.63) than did the non-AA cohort.

CONCLUSION

This nationwide cohort study indicated that AA is associated with increased incidence and risk of VTE.

Established and novel agents for myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are the most commonly diagnosed myeloid malignancy, with >15 000 new cases identified in the United States yearly. Prognostic scoring systems supplant a formal staging approach and, in general, divide patients into those with lower-risk and those with higher-risk MDS. Although treatment goals for patients with lower-risk disease focus on minimizing transfusions and optimizing quality of life, in higher-risk MDS, the goal is to delay transformation to acute leukemia and to prolong survival. In lower-risk patients, isolated cytopenias are treated with erythropoiesis-stimulating agents or growth factors such as thrombopoietin mimetics. For patients with the del(5q) cytogenetic abnormality or those who fail these initial approaches, lenalidomide may be tried, as can experimental agents. Lower-risk patients with multiple cytopenias may be treated with immunosuppressive drugs or low-dose hypomethylating agents. For patients with higher-risk disease, hypomethylating agents are the preferred initial treatment approach, with evaluation for hematopoietic cell transplantation at diagnosis. Several novel agents are being developed for MDS patients who have failed hypomethylating drugs.

Longitudinal Analysis of DNA Methylation in CD34+ Hematopoietic Progenitors in Myelodysplastic Syndrome

Myelodysplastic syndrome (MDS) is a disorder of hematopoietic stem cells (HSCs) that is often treated with DNA methyltransferase 1 (DNMT1) inhibitors (5-azacytidine [AZA], 5-aza-2'-deoxycytidine), suggesting a role for DNA methylation in disease progression. How DNMT inhibition retards disease progression and how DNA methylation contributes to MDS remain unclear. We analyzed global DNA methylation in purified CD34+ hematopoietic progenitors from MDS patients undergoing multiple rounds of AZA treatment. Differential methylation between MDS phenotypes was observed primarily at developmental regulators not expressed within the hematopoietic compartment and was distinct from that observed between healthy hematopoietic cell types. After AZA treatment, we observed only limited DNA demethylation at sites that varied between patients. This suggests that a subset of the stem cell population is resistant to AZA and provides a basis for disease relapse. Using gene expression data from patient samples and an in vitro AZA treatment study, we identified differentially methylated genes that can be activated following treatment and that remain silent in the CD34+ stem cell compartment of high-risk MDS patients. Haploinsufficiency in mice of one of these genes (NR4A2) has been shown to lead to excessive HSC proliferation, and our data suggest that suppression of NR4A2 by DNA methylation may be involved in MDS progression.