Immunosuppressive treatment of aplastic anemia: a prospective, randomized multicenter trial evaluating antilymphocyte globulin (ALG) versus ALG and cyclosporin A

Treatment of newly diagnosed severe aplastic anemia in children: Evidence-based recommendations

Severe aplastic anemia (SAA) is a rare potentially fatal hematologic disorder. Although overall outcomes with treatment are excellent, there are variations in management approach, including differences in treatment between adult and pediatric patients. Certain aspects of treatment are under active investigation in clinical trials. Because of the rarity of the disease, some pediatric hematologists may have relatively limited experience with the complex management of SAA. The following recommendations reflect an up-to-date evidence-based approach to the treatment of children with newly diagnosed SAA.

Diagnosis and treatment of children with aplastic anemia

BACKGROUND

Long-term survival rates among children diagnosed with severe aplastic anemia (SAA) are excellent due to the success of human leukocyte antigen (HLA)-identical related hematopoietic stem cell transplantation (HSCT), concurrent advances in immunosuppressive treatment (IST), and improved supportive care. The challenge in making treatment recommendations for children with SAA, therefore, is to balance the apparent chronicity and morbidity following IST, with the potential up-front toxicity and complications of HSCT.

METHODS

This review provides an update on the diagnosis and a risk-based treatment algorithm for children with acquired SAA. Recent experience using alternative donor HSCT and efforts to extend HSCT eligibility through advances in donor matching, de-escalation of conditioning regimens, and potential marrow graft engineering are highlighted. We discuss IST response rates, risks of relapse, and complications including clonal evolution.

CONCLUSIONS

While good treatment options exist for a majority of children diagnosed with SAA, novel non-transplantation treatments for unresponsive and relapsed patients without suitable transplant donors are needed. Further improvements in outcome will ultimately require a more complete understanding of the pathophysiology of aplastic anemia (AA).

Malignancy: Current Clinical Practice: Current Therapeutic Options in Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are characterized initially by ineffective hematopoiesis and subsequently the frequent development of acute myelogenous leukemias (AML). During the last 15 years, important progress has been made in the understanding of the biology and prognosis of myelodysplastic syndromes. Risk-adapted treatment strategies were established due to the high median age (60-75 years) of MDS-patients and the individual history of the disease (number of cytopenias, cytogenetical changes, transfusion requirements). The use of allogeneic bone marrow transplantation for MDS patients currently offers the only potentially curative treatment, but this treatment modality is not available for the most of the "typical" MDS-patients aged >60 years. Based on in-vitro findings analyzing the potential of several agents to differentiate or to stimulate hematopoietic progenitor cells a number of therapeutic options were evaluated in clinical trials: hematopoietic growth factors (e.g. erythropoietin, G-CSF), differentiation inducers (e.g. retinoids), or cytoprotective substances (amifostine). The role of immunsuppressive agents (antithymocyte globulin, cyclosporine A) either alone or in combination is being actively investigated. Using intensive cytotoxic treatment in patients with advanced MDS or AML after MDS complete remission rates comparable with those known from the treatment of de novo AML were reported. The therapy related toxicity (early death rate <10%) was reduced by using G-CSF given prior ("Priming") and/or after the cytotoxic treatment.

Severe aplastic anemia (SAA): response to cyclosporin A (CyA) in vivo and in vitro

The aim of the present study was to test the effect of cyclosporin A (CyA) in vitro on CFU-GM growth from patients with severe aplastic anemia (SAA). For this purpose, bone marrow (BM) cells from 9 SAA patients and 5 healthy individuals were incubated with or without CyA and then cultured for CFU-GM growth in the presence of exogenous recombinant human GM-CSF (30 ng/ml). SAA patients were tested before or after treatment with CyA, or after treatment with antilymphocyte globulin (ALG). In 3 patients responding to CyA, the addition of CyA in vitro enhanced colony growth from 13 +/- 10 to 40 +/- 20/10(5) BM cells (p = 0.01) - the median increment of colony formation was 2.4-fold. In 5 ALG responders, CyA produced no increment of CFU-GM growth (from 14 +/- 26 to 15 +/- 16/10(5) BM cells, p = 0.1). CyA did not enhance significantly CFU-GM growth in normal controls (from 57 +/- 45 to 58 +/- 81/10(5) BM cells, p = 0.9). In conclusion, it would appear that some patients with SAA can respond to CyA in vivo and in vitro, and ALG responders are not necessarily among these. This is in keeping with different mechanisms of action of CyA and ALG and possibly with the existence of distinct pathogenetic pathways in SAA.

Therapy of aplastic anemia with sequential antithymocyte globulin and cyclosporin

Five consecutive patients with severe aplastic anemia were treated with antithymocyte globulin followed by cyclosporin A. All received antithymocyte globulin initially, and because of lack of response within a 4 week period, cyclosporin was administered subsequently. Hematologic improvement occurred within four months of initiation of cyclosporin. Four patients no longer require blood product support, while one remains transfusion-dependent. In two patients, thrombocytopenia developed when the cyclosporin was tapered but re-institution of the drug resulted in a prompt improvement of counts. These observations indicate that the sequential use of antithymocyte globulin and cyclosporin may be an effective therapeutic approach in the treatment of severe aplastic anemia.

Different haematopoietic growth factors have different capacity in overcoming the in vitro interferon gamma-induced suppression of bone marrow progenitor cells

Interferon gamma (IFN gamma) inhibits haematopoiesis in vitro and an in vivo role in bone marrow suppression has been implied from clinical studies. We investigated the capacity of three recombinant (r), human (h), haematopoietic growth factors to overcome the in vitro IFN gamma inhibition of bone marrow progenitor cells in a methylcellulose culture system. Granulocyte macrophage-colony stimulating factor (GM-CSF) partially reversed IFN gamma-induced suppression of granulocyte-macrophage colony formation, by increasing colony forming units-granulocyte macrophage (CFU-GM) in a proportion ranging from 54-101%. Interleukin-3 (IL-3) and granulocyte-colony stimulating factor (G-CSF) were much less effective. For erythropoiesis, IL-3 was much more effective and partially reversed IFN gamma-mediated inhibition by increasing burst forming units-erythroid (BFU-E) in a proportion ranging from 52-138%. GM-CSF and G-CSF had no significant effect on IFN gamma-induced suppression of BFU-E. In conclusion, haematopoietic growth factors have different capacity to overcome IFN gamma-induced suppression of marrow progenitor cells in vitro. The findings may have therapeutic implications, as combinations of growth factors may be more effective in treating bone marrow failure syndromes.

Antilymphocyte immunoglobulins stimulate peripheral blood lymphocytes to proliferate and release lymphokines

Five different preparations of antilymphocyte immunoglobulins (ATG) and antithymocyte immunoglobulins (ALG) with good or little clinical response were compared for their hematopoietic and immunological activities. All ATG/ALG lots demonstrated complement-mediated cytotoxicity on peripheral blood mononuclear cells. They had different titers of antibody specificities against lymphocyte cell membrane antigens. Neither clinically effective nor ineffective lots demonstrated any apparent colony stimulating activity on bone marrow mononuclear cells. Purified Natural Killer cells failed to be stimulated by ATG/ALG in liquid culture. ATG/ALG demonstrated potent T-cell stimulating activity comparable to phytohemagglutinin. This stimulation was blocked by anti-IL-2 receptor monoclonal antibodies, and was inhibited dose-dependently by cyclosporin-A. Some clinically ineffective ATG/ALG lots also stimulated T cells to release lymphokines. The differences in these characteristics among ATG/ALG lots provide some clues to guide further efforts to elucidate a key mechanism of therapeutic effectiveness.

Cyclosporine therapy of aplastic anaemia, congenital and acquired red cell aplasia

We treated 22 patients with severe aplastic anaemia refractory to antithymocyte globulin (ATG) with cyclosporine, alone or in combination with prednisone. Eight patients showed significant clinical improvement, all but one to transfusion-independence. Although cyclosporine alone was effective, the addition of prednisone resulted in prompter and fuller haematologic improvement. No patient with an absolute granulocyte count less than 0.2 x 10(9)/l responded to treatment. Haematologic remissions were sustained beyond the treatment period. Of nine patients with Diamond-Blackfan syndrome, one showed a complete response to two separate courses of cyclosporine and relapse with withdrawal of therapy, and a second achieved significant reduction in corticosteroid dose without relapse; however, seven cases failed to respond. Two of three adults with acquired pure red cell aplasia recovered. A combination of cyclosporine and corticosteroids may be effective therapy in patients with aplastic anaemia who have failed ATG treatment. Occasional cases of congenital and acquired pure red cell aplasia may also respond to cyclosporine.

Cyclosporin A in the treatment of severe aplastic anemia: description of a case complicated by the development of tubercular pericarditis during treatment

We report on a 62 year-old woman who developed a severe aplastic anemia requiring frequent packed red cell and platelet transfusions. Since conventional pharmacological therapy was ineffective, treatment with Cyclosporin A was started, resulting in a significant increase of leukocyte, platelet, and red cell counts. However, 5 months after the beginning of Cyclosporin A treatment, despite a past medical history not significant for clinical tuberculosis, the patient developed tubercular pericarditis. This report underlines the need for a careful follow-up of Cyclosporin A-treated patients aimed at a prompt diagnosis of possible infectious complications.