AKB-6899

AKB-6899 is an investigational small-molecule hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitor initially developed by Akebia Therapeutics as a second-generation compound related to vadadustat for oncology and anemia-related indications.[3][5][11] Biochemically, AKB-6899 inhibits prolyl hydroxylase domain enzymes, with notable activity against PHD3, leading to stabilization of HIF-α subunits—particularly HIF-2α—and subsequent transcriptional activation of hypoxia-responsive genes.[1][4][5][7] In preclinical models, AKB-6899 selectively increases production of soluble VEGF receptor-1 (sVEGFR-1) from tumor-associated macrophages, attenuating VEGF signaling, reducing tumor angiogenesis, and suppressing tumor growth and metastases while maintaining erythropoietic effects via HIF stabilization.[1][2][4][6][13] The compound has been positioned as a HIF-PH inhibitor with a differentiated antiangiogenic profile, but as of current public reports has not progressed beyond planned early-phase oncology development and remains without approved clinical use.[3][11][12][14]