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 - R. F. Grace; A. Glenthøj; W. Barcellini; M. Verhovsek; J. A. Rothman; M. Morado Arias; D. M. Layton; O. Andres; F. Galactéros; E. J. van Beers; K. Onodera; V. Viprakasit; et al. (HemaSphere, 2022)