Rabbit Antithymocyte Globulin in Treatment of Children with Severe Aplastic Anemia.

In children with severe aplastic anemia (SAA) bone marrow transplantation is the chosen therapy. However, it is only possible in about 15–20% patients who have family donors. Immunosuppressive therapy (IST) is administered in the remaining cases. 105 children in 11 hematology centers of the Polish Pediatric Hematology Group (PPHG) were given IST treatment. 27 patients (12 girls and 15 boys aged 6–16 years) received antithymocyte rabbit globulin (ATG) in the first course of therapy. ATG was administered according to PPHG and Working Party SAA Group of EBMT protocol: ATG 3.75mg/kg iv for 5 days, cyclosporin A (CSA) 5mg/kg orally from day 1 to day 180 and granulocyte-stimulating factor during deep neutropenia. Remission of the disease was assessed on days 84, 112 and 180 from start of therapy on the basis of blood and bone marrow examination. On day 180 remission was obtained in 17 of 27 patients (62.9%), complete remission (CR) in 11 children (40.7%) and partial remission in 6 children (22.2%) There was no response to treatment (NR) in 10 patients (37%). In the no response group, 1 child died and 4 had bone marrow transplants from unrelated donors. The remaining 5 patients received a second course of IST therapy, and 2 of them had CR. In the group of 27 patients, 4 died (14.8%). 2 of them died early (day 52 and day 72 of therapy) due to septicemia and central nervous system (CNS) hemorrhage. The other 2 died late (day 99 and day 365of therapy) due to CNS hemorrhage. Observation time of patients ranged from 1 to 13 years. During this time we noted one relapse. MDS/AML or PNH was not observed in any of the patients. The probability of 13 year survival is 85.1% in our group. Our data suggest that initial SAA treatment with ATG is safe and effective in children. Further studies are needed, however, to assess long-term effectiveness of ATG in IST.