IDH inhibitors (vorasidenib, ivosidenib)

What it is

IDH inhibitors are targeted drugs that block the mutant IDH enzyme, reducing the abnormal substance (2-hydroxyglutarate) that drives IDH-mutant gliomas. Vorasidenib is approved for certain grade 2 IDH-mutant astrocytomas and oligodendrogliomas after surgery; ivosidenib is a related IDH1 inhibitor. These represent a major advance for IDH-mutant gliomas.

Understanding IDH inhibitors (vorasidenib, ivosidenib)

IDH-mutant gliomas depend on the mutant IDH enzyme and the 2-hydroxyglutarate it produces. IDH inhibitors specifically block this mutant enzyme, lowering 2-hydroxyglutarate and slowing tumor growth — a targeted approach aimed at the tumor's underlying driver. Vorasidenib, designed to penetrate the brain, was approved for adults and children (age 12 and older) with certain grade 2 IDH-mutant gliomas (astrocytoma or oligodendroglioma) following surgery; in its key trial, it substantially delayed tumor progression compared with placebo, offering a new option that can postpone the need for radiation and chemotherapy in eligible patients. It is taken as a daily pill. (It was studied in lower-risk grade 2 tumors, not those needing immediate chemoradiation.) Ivosidenib, an IDH1 inhibitor also used in other cancers, has been studied in IDH1-mutant gliomas. IDH inhibitors are a landmark example of targeting a glioma's defining mutation. Understanding IDH inhibitors in gliomas clarifies targeted drugs for IDH-mutant tumors.

Why it matters

Understanding IDH inhibitors helps patients and families see a major advance — targeted pills that block the mutant IDH enzyme, with vorasidenib approved for certain grade 2 IDH-mutant gliomas after surgery, potentially delaying the need for other treatments.