Immunosuppressive treatment of aplastic anemia in Chinese children with antithymocyte globulin and cyclosporine

Anti-thymocyte serum as part of an immunosuppressive regimen in treating haematological immune-mediated diseases in dogs

OBJECTIVES

To report the outcomes associated with the use of rabbit anti-dog thymocyte serum in dogs with haematological immune-mediated diseases.

METHODS

Medical records from 2000 to 2016 of patients diagnosed with immune-mediated haemolytic anaemia, immune-mediated thrombocytopenia, pancytopenia and myelofibrosis were reviewed. All dogs had a severe or refractory disease and received rabbit anti-dog thymocyte serum. Lymphocyte counts were used to monitor the immediate anti-thymocyte effect of therapy; long-term patient outcome was recorded.

RESULTS

A total of 10 dogs were included. All dogs except one had a notable decrease in their lymphocyte count after rabbit anti-dog thymocyte serum; four of nine had a decrease to less than 10% of the initial lymphocyte count and one dog reached 10·8%. All dogs were discharged from the hospital following their treatment. The dog with no alteration of lymphocyte count following therapy with rabbit anti-dog thymocyte serum had refractory immune mediated haemolytic anemia and was euthanised within two weeks. All other cases achieved clinical remission with immunosuppressive therapy eventually being tapered (3 of 10) or discontinued (6 of 10).

CLINICAL SIGNIFICANCE

Rabbit anti-dog thymocyte serum therapy might be of interest as an adjunctive therapy in refractory immune-mediated diseases and suppressed lymphocyte counts in most dogs.

Antithymocyte globulin and cyclosporine in children with aplastic anemia: a developing country experience

BACKGROUND

Human leukocyte antigen-matched bone marrow transplant in the treatment of aplastic anemia is generally not feasible in developing countries due to lack of resources and expertise and immunosuppressive therapy (IST) has been used as an alternative. This study aims to report the long-term outcome of children with aplastic anemia treated with IST [antithymocyte globulin (ATG) and cyclosporine] in our hospital.

PROCEDURE

Case files of children with aplastic anemia who received IST from January 2001 to November 2009 were reviewed.

RESULTS

Thirty-five patients with aplastic anemia (14 very severe aplastic anemia; 21 severe aplastic anemia) were given IST. Seven patients expired within 3 months of therapy and were excluded. The analysis was done in 28 patients (24 male and 4 female; 12 very severe aplastic anemia and 16 severe aplastic anemia). The median age was 10 years (range, 5 to 12 y). Ten patients achieved partial response and 4 patients complete response at 1 year with overall response rate of 50%. Three nonresponders received a second course of ATG after 12 months out of which 2 responded. Hence, overall response including second course was 16 (57%). Three patients relapsed after a median interval of 23 months. The median duration of follow-up of 16 responders was 40 months (range, 15 to 119 mo). In the patients with long-term follow-up for >4 years (n = 7), all were surviving and independent of transfusions.

CONCLUSIONS

In a developing country setting, IST with ATG and cyclosporine seems to be a good alternative treatment for aplastic anemia in children.

Rabbit antithymocyte globulin (thymoglobulin): 25 years and new frontiers in solid organ transplantation and haematology

The more than 25 years of clinical experience with rabbit antithymocyte globulin (rATG), specifically Thymoglobulin, has transformed immunosuppression in solid organ transplantation and haematology. The utility of rATG has evolved from the treatment of allograft rejection and graft-versus-host disease to the prevention of various complications that limit the success of solid organ and stem cell transplantation. Today, rATG is being successfully incorporated into novel therapeutic regimens that seek to reduce overall toxicity and improve long-term outcomes. Clinical trials have demonstrated the efficacy and safety of rATG in recipients of various types of solid organ allografts, recipients of allogeneic stem cell transplants who are conditioned with both conventional and nonconventional regimens, and patients with aplastic anaemia. Over time, clinicians have learnt how to better balance the benefits and risks associated with rATG. Advances in the understanding of the multifaceted mechanism of action will guide research into new therapeutic areas and future applications.

Aplastic anaemia in childhood. Description of two cases and review of the literature

Childhood aplastic anaemia (AA) is an uncommon but potentially fatal haematological disorder. Patients with AA receive supportive care based on transfusions and timely treatment of opportunistic infections, along with specific therapies, which may be bone marrow transplantation and immunosuppressive therapy. Early diagnosis and supportive therapy are required to prevent fatal complications like overwhelming sepsis or life threatening haemorrhages. We report two cases of aplastic anaemia having a different aetiology. The diagnostic work-up and the therapeutic management for each case are described below.

Acquired aplastic anemia in childhood

In comparison to past decades, children who have acquired aplastic anemia (AA) enjoy excellent overall survival that reflects improvements in supportive care, more accurate exclusion of children who have alternate diagnoses, and advances in transplantation and immunosuppressive therapy (IST). Matched sibling-donor hematopoietic stem cell transplants (HSCT) routinely provide long-term survival in the range of 90%, and 75% of patients respond to IST. In this latter group, the barriers to overall and complication-free survival include recurrence of AA, clonal evolution with transformation to myelodysplasia/acute myelogenous leukemia, and therapy-related toxicities. Improvements in predicting responses to IST, in alternative-donor HSCT, and in rationalizing therapy by understanding the pathophysiology in individual patients are likely to improve short- and long-term outcomes for these children.

Current concepts in the pathophysiology and treatment of aplastic anemia

Aplastic anemia, an unusual hematologic disease, is the paradigm of the human bone marrow failure syndromes. Almost universally fatal just a few decades ago, aplastic anemia can now be cured or ameliorated by stem-cell transplantation or immunosuppressive drug therapy. The pathophysiology is immune mediated in most cases, with activated type 1 cytotoxic T cells implicated. The molecular basis of the aberrant immune response and deficiencies in hematopoietic cells is now being defined genetically; examples are telomere repair gene mutations in the target cells and dysregulated T-cell activation pathways. Immunosuppression with antithymocyte globulins and cyclosporine is effective at restoring blood-cell production in the majority of patients, but relapse and especially evolution of clonal hematologic diseases remain problematic. Allogeneic stem-cell transplant from histocompatible sibling donors is curative in the great majority of young patients with severe aplastic anemia; the major challenges are extending the benefits of transplantation to patients who are older or who lack family donors. Recent results with alternative sources of stem cells and a variety of conditioning regimens to achieve their engraftment have been promising, with survival in small pediatric case series rivaling conventional transplantation results.