Unresponsiveness to erythropoietin therapy in a case of Blackfan Diamond anemia

Diamond-Blackfan anemia with mutation in RPS19: A case report and an overview of published pieces of literature

Introduction

Diamond-Blackfan anemia (DBA), one of a rare group of inherited bone marrow failure syndromes, is characterized by red cell failure, the presence of congenital anomalies, and cancer predisposition. It can be caused by mutations in the RPS19 gene (25% of the cases).

Methods

This case report describes a 10-month-old boy who presented with 2 months' history of gradually increasing weakness and pallor.

Results

The patient was diagnosed as a case of DBA based on peripheral blood finding, bone marrow aspiration with trephine biopsy reports, and genetic mutation analysis of the RPS19 gene. His father refused hematopoietic stem cell transplantation for financial constraints. Patient received prednisolone therapy with oral folic acid and iron supplements.

Conclusion

Hemoglobin raised from 6.7 to 9.8g/dL after 1 month of therapeutic intervention.

PPAR-α and glucocorticoid receptor synergize to promote erythroid progenitor self-renewal

Many acute and chronic anemias, including hemolysis, sepsis, and genetic bone marrow failure diseases such as Diamond-Blackfan Anemia (DBA), are not treatable with erythropoietin (Epo), because the colony-forming unit erythroid progenitors (CFU-Es) that respond to Epo are either too few in number or are not sensitive enough to Epo to maintain sufficient red blood cell production ^{1,2,3–5,6,7,8,9}. Treatment of these anemias requires a drug that acts at an earlier stage of red cell formation and enhances the formation of Epo-sensitive CFU-E progenitors. Recently we showed that glucocorticoids specifically stimulate self-renewal of the early erythroid progenitor, the burst-forming unit erythroid (BFU-E), and increase the production of terminally differentiated erythroid cells ^10,11. Here we demonstrate that activation of the peroxisome proliferator-activated receptor alpha (PPARα) by PPARα agonists, GW7647 and fenofibrate, synergizes with glucocorticoid receptor (GR) to promote BFU-E self-renewal. Over time these agonists greatly increase production of mature red blood cells in cultures both of mouse fetal liver BFU-Es and of mobilized human adult CD34⁺ peripheral blood progenitors, the latter employing a new and effective culture system that generates normal enucleated reticulocytes. While PPARα^−/− mice show no hematological difference from wild-type mice in both normal and phenylhydrazine (PHZ)-induced stress erythropoiesis, PPARα agonists facilitate recovery of wild-type mice, but not PPARα^−/− mice, from PHZ-induced acute hemolytic anemia. We also showed that PPARα alleviates anemia in a mouse model of chronic anemia. Finally, both in control and corticosteroid-treated BFU-E cells PPARα co-occupies many chromatin sites with GR; when activated by PPARα agonists, additional PPARα is recruited to GR-adjacent sites and presumably facilitates GR-dependent BFU-E self-renewal. Our discovery of the role of PPARα agonists in stimulating self-renewal of early erythroid progenitor cells suggests that the clinically tested PPARα agonists we used may improve the efficacy of corticosteroids in treating Epo resistant anemias.

Progress towards mechanism-based treatment for Diamond-Blackfan anemia

Diamond-Blackfan anemia (DBA) is a congenital erythroid hypoplastic anemia, characterized by macrocytic anemia, reticulocytopenia, and severely reduced numbers of erythroid precursors in the bone marrow. For more than fifty years, glucocorticoids have remained the main option for pharmacological treatment of DBA. While continuous glucocorticoid administration increases hemoglobin levels in a majority of DBA patients, it also causes severe side effects. There is therefore a great need for more specific and effective treatments to boost or replace the use of glucocorticoids. Over the years, many alternative therapies have been tried out, but most of them have shown to be ineffective. Here we review previous and current attempts to develop such alternative therapies for DBA. We further discuss how emerging knowledge regarding the pathological mechanism in DBA and the therapeutic mechanism of glucocorticoids treatment may reveal novel drug targets for DBA treatment.

Diamond Blackfan anemia treatment: past, present, and future

Despite significant improvements in our understanding of the pathophysiology of Diamond Blackfan anemia (DBA), there have been few advances in therapy. The cornerstones of treatment remain corticosteroids, chronic red blood cell transfusions, and hematopoietic stem cell transplantation, each of which is fraught with complications. In this article, we will review the history of therapies that have been offered to patients with DBA, summarize the current standard of care, including management of side effects, and discuss novel therapeutics that are being developed in the context of the research into the roles of ribosomal haplo-insufficiency and p53 activation in Diamond Blackfan anemia.

How I treat Diamond-Blackfan anemia

Diamond-Blackfan anemia (DBA) is characterized by red cell failure, the presence of congenital anomalies, and cancer predisposition. In addition to being an inherited bone marrow failure syndrome, DBA is also categorized as a ribosomopathy as, in more than 50% of cases, the syndrome appears to result from haploinsufficiency of either a small or large subunit-associated ribosomal protein. Nonetheless, the exact mechanism by which haploinsufficiency results in erythroid failure, as well as the other clinical manifestations, remains uncertain. New knowledge regarding genetic and molecular mechanisms combined with robust clinical data from several international patient registries has provided important insights into the diagnosis of DBA and may, in the future, provide new treatments as well. Diagnostic criteria have been expanded to include patients with little or no clinical findings. Patient management is therefore centered on accurate diagnosis, appropriate use of transfusions and iron chelation, corticosteroids, hematopoietic stem cell transplantation, and a coordinated multidisciplinary approach to these complex patients.

Diagnosing and treating Diamond Blackfan anaemia: results of an international clinical consensus conference

Diamond Blackfan anaemia (DBA) is a rare, genetically and clinically heterogeneous, inherited red cell aplasia. Classical DBA affects about seven per million live births and presents during the first year of life. However, as mutated genes have been discovered in DBA, non-classical cases with less distinct phenotypes are being described in adults as well as children. In caring for these patients it is often difficult to have a clear understanding of the treatment options and their outcomes because of the lack of complete information on the natural history of the disease. The purpose of this document is to review the criteria for diagnosis, evaluate the available treatment options, including corticosteroid and transfusion therapies and stem cell transplantation, and propose a plan for optimizing patient care. Congenital anomalies, mode of inheritance, cancer predisposition, and pregnancy in DBA are also reviewed. Evidence-based conclusions will be made when possible; however, as in many rare diseases, the data are often anecdotal and the recommendations are based upon the best judgment of experienced clinicians. The recommendations regarding the diagnosis and management described in this report are the result of deliberations and discussions at an international consensus conference.

Diamond blackfan anemia stem cells fail to repopulate erythropoiesis in NOD/SCID mice

Diamond Blackfan Anemia (DBA) is a congenital disorder characterized by decreased red blood cell production and developmental abnormalities. We herein show that DBA progenitors produced lower numbers of phenotypically normal erythroid colonies in vitro, whereas nonerythroid colonies were normally abundant and developed. To determine whether DBA stem cells are capable of producing early erythroid, monocyto-granulocytic, and lymphoid progenitors in vivo we used a mouse xenotransplantation model. We demonstrate that DBA stem cells poorly repopulated erythroid progeny in NOD/SCID mice, whereas the monocyto-granulocytic and lymphoid progenies were repopulated normally. Therefore, we conclude that disordered DBA erythropoiesis may be a result of defective erythroid-lineage commitment and maintenance of early erythroid progenitors.

Biology and pharmacology of hematopoietic growth factors

Several glycoproteins that control blood formation have recently been characterized. Through their overlapping, synergizing, and antagonistic effects, they regulate hematopoiesis in a highly differentiated network. Large scale production of these colony stimulating factors (CSFs) has been made available by recombinant DNA technology, and a series of clinical studies in a variety of indications has been finished. In general, the subcutaneous application seems to be superior to the intravenous injection and causes less toxicity. Erythropoietin has been shown to be a highly effective treatment for anemia in patients with chronic renal failure. Granulocyte colony stimulating factor and granulocyte-macrophage colony stimulating factor are capable of ameloriating the chemotherapy induced neutropenia, and to abbreviate the time span of myeloaplasia after bone marrow transplantation. The potentials of other colony stimulating factors like Interleukin 1 and Interleukin 3, and combination regimens of several CSFs will be discussed.