FT-4202, a selective pyruvate kinase R activator for sickle cell disease

Anemia in patients with sickle cell disease (SCD) increases 2,3-diphosphoglycerate (2,3-DPG), decreasing hemoglobin-oxygen (HbO₂) affinity to improve oxygen offloading and promote hemoglobin polymerization (sickling) of red blood cells (RBCs). We report the discovery of FT-4202, an investigational, selective pyruvate kinase type-R (PKR) activator with a multimodal mechanism of action and potential to increase ATP and decrease 2,3-DPG, resulting in increased HbO₂ affinity, decreased Hb polymerization, and improved RBC health. FT-4202 was identified via structure-enabled lead optimization medicinal chemistry using X-ray crystallography, molecular modeling, and thermal shift assays. FT-4202, an allosteric PKR activator, stabilizes the tetrameric enzyme and increases PKR activity in human and mouse RBCs in vitro. Seven-day oral administration of FT-4202 in Berkeley SCD mice reduced 2,3-DPG, increased HbO₂ affinity, and reduced RBC sickling versus control. There were no adverse in vitro safety findings. FT-4202 offers a therapeutic opportunity to modify the course of SCD.