Discovery of a Potent and Orally Bioavailable Hypoxia-Inducible Factor 2α (HIF-2α) Agonist and Its Synergistic Therapy with Prolyl Hydroxylase Inhibitors for the Treatment of Renal Anemia

Activation of hypoxia-inducible factor 2 (HIF-2) has emerged as a potent renal anemia treatment strategy. Here, the benzisothiazole derivative 26 was discovered as a novel HIF-2α agonist, which first demonstrated nanomolar activity (EC50 = 490 nM, Emax = 349.2%) in the luciferase reporter gene assay. Molecular dynamics simulations indicated that 26 could allosterically enhance HIF-2 dimerization. Furthermore, compound 26 had a good pharmacokinetic profile (the oral bioavailability in rats was 41.38%) and an in vivo safety profile (the LD50 in mice was greater than 708 mg·kg–1). In the in vivo efficacy assays, the combination of 26 and the prolyl hydroxylase inhibitor, AKB-6548, was confirmed for the first time to synergistically increase the plasma erythropoietin level in mice (from 260 to 2296 pg·mL–1) and alleviate zebrafish anemia induced by doxorubicin. These results provide new insights for HIF-2α agonists and the treatment of renal anemia.