State of the Art of IDH Inhibitors: Emerging Questions and Perspectives

Isocitrate Dehydrogenases (IDH) are ubiquitous enzymes essential for cellular metabolism, including the Krebs cycle, glutamine metabolism, lipogenesis, and redox balance. Mutations in IDH1 and IDH2 are implicated in several tumors - gliomas, Acute Myeloid Leukemia (AML), cholangiocarcinoma - altering enzyme activity and causing the overproduction of 2-hydroxyglutarate (2-HG). This oncometabolite disrupts α-KGdependent proteins, impairing key processes such as differentiation, division, and DNA repair. Understanding these genetic, biochemical, and clinical aspects has made IDH enzymes promising therapeutic targets, prompting the development of targeted inhibitors for tumors harboring IDH1 or IDH2 point mutations. Selective inhibitors like ivosidenib (AG-120) and enasidenib (AG-221), targeting mutant IDH1 and IDH2 respectively, block 2- HG production and induce differentiation, achieving clinical success - particularly in AML. However, resistance due to secondary mutations, especially in the allosteric binding site, remains a major obstacle. In response, novel approaches have emerged, such as covalent inhibitors like LY3410738, which irreversibly bind mutant residues, and dual inhibitors like vorasidenib (AG-881), which act on both IDH1 and IDH2 mutations and penetrate the blood-brain barrier for treating solid tumors. Still, many clinical factors must be considered. This review explores the current landscape of IDH-targeted therapies, emphasizing the need for novel inhibitors and highlighting innovative strategies, including the design of smaller, more potent molecules with favorable pharmacokinetics and the potential of drug repositioning. We underscore that discovering new antitumor compounds targeting IDH requires a collaborative effort across biomedical fields. These advancements aim to overcome resistance, broaden therapeutic options, and improve the effectiveness of IDH-targeted treatments.