Aplastic anemia is a rare bone marrow disorder characterized by pancytopenia.1 Most cases are considered idiopathic, and the incidence varies greatly worldwide.2 Some studies have linked the disease to exposure to certain chemotherapy drugs, chemicals such as benzene, and other toxic agents.1

Until recently, patients with aplastic anemia had poor prognosis, with mortality estimates of 80% at 1 year after diagnosis for severe cases.1 The disorder can now be cured or managed using hematopoietic stem cell transplantation (HSCT) or immunosuppressive therapy (IST); recent 5-year survival rate estimates for severe aplastic anemia are 50% to 60%.3

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Matched family donor HSCT is used as frontline treatment in patients younger than 40 years, and matched unrelated donor HSCT is accepted as frontline treatment in appropriate patients aged 20 years or younger.3 Typically, frontline IST is used in patients who lack a matched family donor and are older than 40 years or have significant comorbidities.

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Standard IST consists of horse antithymocyte globulin (ATG) plus cyclosporine A. This regimen yields a response rate of 50% to 70% and an overall survival rate of 75% to 90%. Rabbit ATG can be used when horse ATG is unavailable. In severe cases, the thrombopoietin receptor agonist eltrombopag may be used in combination with IST.3

After an initial course of frontline standard IST, approximately 60% of patients have refractory/relapsed aplastic anemia and are need secondary treatment, which presents a challenge for the management of the disease.3

In a review published in Expert Review of Hematology, Filomena Pierri, MD, and Carlo Dufour, MD, of the Hematology Unit at the G Gaslini Children’s Research Hospital in Italy, reported their findings from a literature review on second-line treatment of aplastic anemia and provided an algorithm to support the treatment decision making process for severe cases of the disease.3

Given the extreme rarity of aplastic anemia, studies with different levels of evidence were included as well as guidelines from national societies and other review articles. After failure of frontline IST, the most commonly used treatments were HSCT, a second course of IST, and thrombopoietin mimetics alone or in combination with immunosuppression. Alemtuzumab, androgens, and oral cyclosporine A were also used as monotherapy.