This is a 2-part, open-label, interventional study conducted in approximately 42 subjects with AML harboring an IDH2 mutation. The overall study is a 3-arm investigation of the PK effects of enasidenib at steady state on the probe compounds. (Part 1), followed by treatment continuation up to 28 months (Part 2). Each arm utilizes different probe compounds; enrolls a separate cohort of approximately 14 subjects; and consists of 2 parts - investigation of the PK effects of enasidenib on the respective probe compound(s) (Part 1), followed by an enasidenib treatment extension (Part 2).