A vaccine targeting mutant IDH1 in newly diagnosed glioma.
Level 4 - case-series / case-control
Single-arm, open-label phase I trial without a control group
PubMed 33762734 · doi:10.1038/s41586-021-03363-z
What was done
A multicenter, single-arm, open-label phase I trial (NOA16, NCT02454634) evaluated an IDH1(R132H)-specific peptide vaccine in 33 patients with newly diagnosed WHO grade 3 and 4 IDH1(R132H)+ astrocytomas. The primary endpoint was safety. Secondary and exploratory assessments included immune responses across MHC alleles, 2- and 3-year progression-free and death-free rates, correlation of a mutation-specificity score with pre-treatment tumor tissue neoantigen presentation, and single-cell RNA and T-cell receptor sequencing of tumor-infiltrating lymphocytes.
What was found
The trial met its primary safety endpoint, with vaccine-related adverse events limited to grade 1. Vaccine-induced immune responses occurred in 93.3% of patients across multiple MHC alleles. The 3-year progression-free and death-free rates were 0.63 and 0.84, respectively. Patients mounting an immune response had a 2-year progression-free rate of 0.82, whereas 2 patients without an immune response experienced tumor progression within 2 years. A mutation-specificity score correlated with intratumoral IDH1(R132H) neoantigen presentation. Pseudoprogression was frequent and associated with peripheral T-cell responses; in one patient with pseudoprogression, infiltrating CD40LG+ and CXCL13+ T-helper cells were dominated by a single IDH1(R132H)-reactive clonotype.
Why it matters
This study shows that a shared clonal neoepitope vaccine targeting mutant IDH1 is safe, highly immunogenic across diverse MHC alleles, and capable of generating intratumoral inflammatory responses in newly diagnosed high-grade gliomas.
Limits
The study is a non-randomized, open-label, single-arm phase I trial with a small sample size (n = 33). Without a control group, clinical efficacy and survival outcomes cannot be differentiated from standard-of-care prognosis or natural variation in IDH1-mutant disease courses. Single-cell sequencing of tumor-infiltrating lymphocytes was limited to select cases.
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