|With the exception of the reduced group in which an initiating event is documented, the vast majority of severe acquired aplastic anemia (SAA) cases are autoimmune, secondary to exposure to a self, chemical or viral antigen. The fact that the majority of SAA patients respond to immunosuppressive therapy (IST), including anti thymocyte globulin (ATG) combined with cyclosporine A (CsA), as well as to cyclophosphamide (CY), supports this concept.
The rationale for the administration of IST to SAA patients without hematopoietic stem cell allografting then relies on the evidence that a hyperactivated immune system drives auto reactive T-cell clones to destroy the individualâs own stem and hematoprogenitor cells in the bone marrow.
A response rate up to 80%, with a five-year survival of 75% to 93% for SAA patients immunosuppressed with ATG plus CsA, and granulocyte-colony stimulating factor (G-CSF), has been reported. Aplastic anemia patients however, can have a partial response, fail to respond, relapse, or remain dependent of CsA. Despite these drawbacks, the combination of ATG plus CsA is currently recommended as the treatment of choice for SAA patients without an HLA-matched stem cell donor.
Jos Carlos Jaime-rez, Long-Term Remission and Bone Marrow Findings in Children with Severe Aplastic Anemia Immunosuppressed with High Doses of Cyclophosphamide