Ambit Biosciences was developing AC-430, a potent inhibitor of Janus kinase 2 (JAK2) for the treatment of cancer and autoimmune diseases. AC-430 is a racemic mixture (50/50) of two enantiomers, AC410 and AC409. In preclinical studies, AC-430 has exhibited potency against JAK2 and V617F mutated JAK2 in cell-based models that is at least equivalent to, and in most cases superior to, competing JAK2 inhibitors. In preclinical oncology and autoimmune models, AC-430 is well tolerated and has significant efficacy at oral doses as low as 10 mg/kg/day.