Evaluation Of Pharmacokinetic-Pharmacodynamic (Pkpd) Relationship Of An Oral, Selective, First-In-Class, Potent Idh2 Inhibitor, Ag-221, From A Phase 1 Trial In Patients With Advanced Idh2 Mutant Positive Hematologic Malignancies

Introduction: Isocitrate dehydrogenase (IDH) is a critical enzyme in the citric acid cycle, catalyzing the oxidative decarboxylation of isocitrate to produce alpha-ketoglutarate (a-KG). The mutant IDH are not catalytically inactive enzymes, but rather possess novel enzymatic activities, catalyzing the reduction of α-KG to the ‘oncometabolite’ 2-hydroxyglutarate (2-HG), which has been found to be elevated in patients with several tumor types, including acute myelogenous leukemia (AML). AG-221 is an oral, selective, first-in class, potent inhibitor of the IDH2 mutant protein. The compound has been demonstrated to reduce 2-HG levels by >90% and reverse histone and DNA hypermethylation in vitro, and to induce differentiation in leukemia cell models. In vivo pharmacokinetic/pharmacodynamic (PK/PD) studies in a U87MG IDH2 (R140Q) xenograft mouse model demonstrated robust plasma 2-HG lowering, and the correlation between PK (AG-221 exposure) and PD (the inhibition of 2-HG production) was used for human efficacious exposure projection. The PK/PD correlation was further confirmed in a primary human AML xenograft model in mice. These results are compared to early PK/PD results from the ongoing first-in-human Phase I study of AG-221 in patients with advanced IDH2 mutant positive hematologic malignancies [NCT01915498].