P1545: DURABILITY OF HEMOGLOBIN RESPONSE AND REDUCTION IN TRANSFUSION BURDEN IS MAINTAINED OVER TIME IN PATIENTS WITH PYRUVATE KINASE DEFICIENCY TREATED WITH MITAPIVAT IN A LONG-TERM EXTENSION STUDY. (23rd June 2022) - Grace, R. F.; Glenthøj, A.; Barcellini, W.; Verhovsek, M.; Rothman, J. A.; Morado Arias, M.; Layton, D. M.; Andres, O.; Galactéros, F.; van Beers, E. J.; Onodera, K.; Viprakasit, V.; et al.