Ivosidenib (Tibsovo®) is a small molecule, orally available inhibitor of mutated 
cytosolic isocitrate dehydrogenase 1 (IDH1) that is being developed by Agios 
Pharmaceuticals for the treatment of cancer in patients with IDH1 mutations. The 
mutated form of the IDH1 enzyme produces a metabolite, 2-hydroxyglutarate 
(2-HG), which is thought to play a role in the formation and progression of 
acute myeloid leukaemia (AML), gliomas and other cancers. Elevated 2-HG levels 
interfere with cellular metabolism and epigenetic regulation, thereby 
contributing to oncogenesis. Ivosidenib targets the IDH1 metabolic pathway to 
prevent a build-up of the oncometabolite 2-HG. This article summarizes the 
milestones in the development of ivosidenib leading to this first approval in 
the USA for the treatment of patients with relapsed or refractory AML with a 
susceptible IDH1 mutation. Clinical development for AML, cholangiocarcinoma, 
glioma, myelodysplastic syndromes and solid tumours is ongoing worldwide.