Long-Term Efficacy and Safety of the Oral Pyruvate Kinase Activator Mitapivat in Adults with Non-Transfusion-Dependent Alpha- or Beta-Thalassemia

Background: The thalassemias are a group of red blood cell (RBC) disorders in which ineffective erythropoiesis and hemolysis occur due to imbalanced production and precipitation of globin chains. Thalassemic RBCs have insufficient levels of ATP to meet increased energy demands associated with globin chain imbalance, protein degradation, and cellular oxidative stress responses. Mitapivat (AG-348) is a first-in-class, small-molecule, oral activator of RBC pyruvate kinase (PKR), a key enzyme regulating ATP production via glycolysis. In a phase 2, open-label trial of mitapivat in adults with α- or β-non-transfusion-dependent (NTD) thalassemia (NCT03692052), 80.0% (16/20) of patients (pts) met the primary endpoint of a hemoglobin (Hb) response (increase ≥ 1.0 g/dL from baseline at 1 or more assessments between Wks 4-12, inclusive). Improvements in markers of hemolysis and erythropoiesis were also observed in pts and mitapivat was generally well tolerated.