Antithymocyte Rabbit Globulin Is Safe and Effective in Children with Severe Aplastic Anemia Report Polish Pediatric Hematology Group (Warszawa, Krakow, Wroclaw, Bydgoszcz, Poznan, Lodz, Bialystok, Szczecin, Gdansk).

Abstract 4220

Bone marrow transplantation (BMT) is a therapy of choice in children with severe aplastic anemia (SAA), but it is possible only in about 15-20% patients who have family donors, so the majority of them received the immunosuppressive therapy (IST).

We want to present the results of IST obtained in 116 children treated between 1993-2008 years at 11 pediatric hematology centers of the Polish Pediatric Hematology Group (PPHG),, 55 patients (22 girls and 33 boys aged 0,6-17,5 years) received antithymocyte rabbit globulin (ATG) as a 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 112, 180 and 360 from start of therapy on the basis of blood and bone marrow examination. The results on 112 and 180 were similar. The remission was achieved in 28 of 55 children (51%), complete remission (CR) in 5 children (9%), and partial remission (PR) in 23 children (42%). On day 360 remission was obtained in 30 of 55 patients (42 %), CR in 10 children (18%) and PR in 20 children (36%) There was no response to treatment (NR) in 25 patients (45%).

In the group of 55 patients, 15 died (27%). 5 of them died early (day 52 and day 72 of therapy) due to septicemia and central nervous system (CNS) hemorrhage. The other 10 died late (day 99 and day 360 of therapy) due to CNS hemorrhage. Observation time of patients ranged from 1 to 14 years. During this time we noted four relapse. PNH was observed in one patient. The probability of 14 year survival in our group of patients treated initially with rabbit ATG is 72,7%. The results in the last follow up (Jun 2009) are better then earlier. We observed CR in 23/55 children (42%), PR in 10/55 (18%), NR 18/55 (33%). o information about 4 patients.

We conclude that initial treatment with rabbit ATG is safe and effective in children. Further studies are needed, to assess long-term effectiveness of rabbit ATG in IST.