P819: TRANSPLANT, TREATMENT AND TRANSFUSION FREE (TTT-FREE) SURVIVAL AS RELEVANT CLINICAL ENDPOINT AFTER IMMUNOSUPPRESSIVE TREATMENT FOR ACQUIRED APLASTIC ANEMIA IN ADULTS oleh E. Koster, C. Halkes, E. Bogers, C. Hazenberg, F. Heubel-Moenen, S. Langemeier, E. Meijer, E. Nur, M. Raaijmakers, T. Snijders, M. de Witte, J. Tjon, L. de Wreede