Anemia in β-
thalassemia is related to ineffective erythropoiesis and reduced red cell survival. Excess free
heme and accumulation of unpaired α-
globin chains impose substantial oxidative stress on β-thalassemic erythroblasts and erythrocytes, impacting cell metabolism. We hypothesized that increased
pyruvate kinase activity induced by
mitapivat (AG-348) in the Hbbth3/+ mouse model for β-
thalassemia would reduce chronic
hemolysis and ineffective erythropoiesis through stimulation of red cell glycolytic metabolism. Oral
mitapivat administration ameliorated ineffective erythropoiesis and
anemia in Hbbth3/+ mice. Increased
ATP, reduced
reactive oxygen species production, and reduced markers of
mitochondrial dysfunction associated with improved mitochondrial clearance suggested enhanced metabolism following
mitapivat administration in β-
thalassemia. The amelioration of responsiveness to
erythropoietin resulted in reduced soluble erythroferrone, increased liver Hamp expression, and diminished liver
iron overload.
Mitapivat reduced duodenal Dmt1 expression potentially by activating the
pyruvate kinase M2-HIF2α axis, representing a mechanism additional to Hamp in controlling
iron absorption and preventing β-
thalassemia-related liver
iron overload. In ex vivo studies on erythroid precursors from patients with β-
thalassemia,
mitapivat enhanced erythropoiesis, promoted erythroid maturation, and decreased apoptosis. Overall,
pyruvate kinase activation as a treatment modality for β-
thalassemia in preclinical model systems had multiple beneficial effects in the erythropoietic compartment and beyond, providing a strong scientific basis for further clinical trials.