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Vorasidenib (Voranigo) post-INDIGO — biology, high-grade extension, and combinations

Post-INDIGO update for vorasidenib in IDH-mutant glioma, anchoring the AACR-Novocure CDA-funded TTF + vorasidenib program plus RT, vaccine, and immune combination signals.

  • Speaker(s): Ingo K. Mellinghoff, MD (MSK; INDIGO co-PI); Patrick Y. Wen (DFCI); Timothy F. Cloughesy (UCLA); Zhaohui Wang, PhD (Terasaki Institute; AACR-Novocure CDA recipient for TTF + vorasidenib)
  • Affiliation: MSK / DFCI / UCLA; Terasaki Institute for Biomedical Innovation (TTF combination arm); Servier (sponsor)
  • Anchor type: targeted therapy / trial + tool (post-marketing biology + combination design)
  • Day / session: Day 1 (Mon Mar 23, 2026), IDH-mutant Glioma session
  • Status: post-meeting; details captured from AACR Brain 26 program notes, the published INDIGO Ph3 (NEJM 2023), CURE-reported high-grade safety follow-up, and the AACR press release naming Wang's TTF + vorasidenib CDA; cohort-level update numerics TBD pending abstract supplement

Headline finding

Three threads in one session: (1) post-INDIGO biology and post-marketing surveillance of vorasidenib (Voranigo) in grade 2 IDH-mutant astrocytoma / oligodendroglioma — the first targeted therapy approved in this indication (FDA Aug 2024); (2) extension into higher-grade (grade 3 / 4) IDH-mut glioma, building on the CURE-reported safety/tolerability signal; and (3) the combination program — TTF (Tumor Treating Fields) per the AACR-Novocure CDA-funded preclinical + Ph1 design (Wang, Terasaki), plus RT and vaccine combinations. Specific updated PFS/biomarker numbers from the Brain 26 talk TBD.

Mechanism / methodology

Vorasidenib is a brain-penetrant dual mutant IDH1 / IDH2 inhibitor that suppresses oncometabolite D-2-hydroxyglutarate (D-2-HG), driving downstream re-expression of methylation-silenced tumor-suppressor and differentiation programs. The TTF combination rationale (per the CDA award) is that low-intensity alternating electric fields disrupt mitosis and may synergize with IDH-inhibitor-induced differentiation pressure; the program is preclinical-to-Ph1. Vaccine combinations leverage the IDH1R132H peptide (see dkfz-idh-vaccine.md).

Mechanism / methodology deep dive

Underlying biology. Mutant IDH1 (R132H most common) and IDH2 produce the oncometabolite D-2-hydroxyglutarate (D-2-HG), which competitively inhibits α-KG-dependent dioxygenases including TET2 (DNA demethylation) and the KDM family (histone demethylation), producing the hypermethylator (G-CIMP) phenotype and a differentiation block. D-2-HG also suppresses local T-cell and NK function, contributing to an immunologically cold TME.

Therapeutic design. Vorasidenib (AG-881) is an orally bioavailable, brain-penetrant dual allosteric inhibitor of mutant IDH1/IDH2, designed for CNS exposure that ivosidenib (IDH1-only) and enasidenib (IDH2-only) lack. INDIGO (NEJM 2023) used 40 mg QD in non-enhancing grade 2 IDH-mut glioma post-surgery; combination arms layer (a) TTF at 200 kHz (Optune-class) per the Wang CDA, (b) RT timing studies, and (c) IDH1R132H peptide vaccine + checkpoint.

Resistance / failure modes. Known: incomplete D-2-HG suppression in tumor core, intra-tumoral heterogeneity of IDH activity, and second-site mutations / dimer-interface mutations conferring inhibitor resistance (documented for ivosidenib in AML, plausible in glioma). Anticipated: clonal selection of IDH-wild-type-like glioblastoma transformation under prolonged inhibition.

Translational gaps. Optimal sequencing with RT/TMZ in higher-grade IDH-mut, biomarkers for vorasidenib responders beyond IDH-mut status, and whether 2-HG suppression genuinely improves vaccine immunogenicity are all open. TTF + vorasidenib remains preclinical → Ph1 with no efficacy readout yet.

Where it fits in the corpus

  • AACR 2026: IDH-mut targeted-therapy biology echoed in Annual; cross-link to the IDH-mut neoantigen vaccine session.
  • ASCO 2026: vorasidenib post-INDIGO Ph2 / combination registrations expected on the neuro-onc agenda.
  • SITC 2026: IDH-mut peptide-vaccine + checkpoint thread.
  • Related Brain 26 entries: dkfz-idh-vaccine.md, suva-glioma-cell-states.md.

Open questions

  • Does TTF + vorasidenib produce a clinically meaningful preclinical → Ph1 signal that justifies a Ph2 design, and at what disease grade?
  • Where vorasidenib sits relative to RT / TMZ in newly-diagnosed grade 3 / 4 IDH-mut — earlier-line vs salvage — remains undefined.