Immunosuppressive Therapy with Antithymocyte Globulin and Cyclosporine for Fulminant Aplastic Anemia.

Survival after immunosuppressive therapy (IST) for aplastic anemia (AA) depends on disease severity, which is classified according to polymorphic neutrophil (PMN) count as follows: nonsevere AA (nSAA; PMN > 0.5 × 10⁹/L); severe AA (SAA; PMN 0.2 – 0.5 × 10⁹/L); and very severe AA (vSAA; PMN < 0.2 × 10⁹/L). Although patients with fulminant AA, defined as PMN = 0 for > 2 weeks, generally have poor outcome, no data are available for a large cohort. Therefore, we evaluated the outcome of children with fulminant AA who were enrolled in an AA-97 study and received ATG, cyclosporine, and granulocyte colony-stimulating factor (G-CSF).

A total of 288 children newly diagnosed with AA (median age, 8 years) were enrolled into an AA-97 study between 1997 and 2006 and treated with a combination of horse antithymocyte globulin (Lymphoglobulin^®) and cyclosporine. For patients with PMN < 0.2 × 10⁹/L, G-CSF was added. Patients were classified into 3 groups according to disease severity as follows: fulminant (PMN 0, n = 35); vSAA (PMN 0 – 0.2 × 10⁹/L, n = 129); and SAA (PMN 0.2 – 0.5 × 10⁹/L, n = 124). Of the 35 patients with fulminant AA, 8 had a history of acute hepatitis at the time of diagnosis. One case was considered to be drug-induced AA. The remaining 26 patients had unknown etiology. We evaluated the response rate (RR) at 6 months, 5-year overall survival (OS), and 5-year failure free survival (FFS). Treatment failure was defined as death due to any cause, a requirement for a secondary therapy, relapse, clonal evolution to myelodysplastic syndrome/acute myelocytic leukemia, and paroxysmal nocturnal hemoglobinuria.

The children with fulminant AA showed a significantly lower RR than those with vSAA and SAA (40.0%, 62.8%, and 64.5%, respectively; p =.023). Of the 20 non-responders in the fulminant AA group, 11 were rescued by alternative donor stem cell transplantation, and 5 achieved a late response after 6 months. As a result, no significant difference was noted in 5-year OS and 5-year FFS among the children with fulminant AA, vSAA, and SAA (88.5%/48.2%, 95.8%/65.1%, and 96.8%/68.1%, respectively).

In consideration of favorable OS, the choice of IST is indicated in children with fluminant AA who lack an HLA-matched family donor.

No relevant conflicts of interest to declare.