IDH1-R132H peptide vaccine extends median overall survival to 106.1 months in grade IV astrocytoma

Patients with IDH1-mutant astrocytomas, particularly high-grade forms, face a challenging prognosis despite standard treatments. The IDH1R132H mutation is a common clonal driver in these gliomas, creating a unique neoepitope recognized by the immune system. Targeting this specific mutation with an immunotherapy, such as a peptide vaccine, offers a promising strategy to induce a targeted anti-tumor immune response. Current standard-of-care often provides limited long-term survival benefits, highlighting the need for novel adjuvant therapies that can leverage the tumor's unique molecular signature.

This multicenter, single-arm, open-label, first-in-human phase 1 trial (NOA16) evaluated the IDH1-R132H peptide vaccine (IDH1-vac) in 33 participants. The cohort consisted of newly diagnosed grade III and IV IDH1-R132H+ astrocytoma patients (WHO 2007 classification). The vaccine was integrated into standard of care, with primary endpoints focused on safety and immunogenicity. This report details the long-term clinical and immunological follow-up, serving as secondary and translational endpoints, to assess the vaccine's sustained impact.

The trial demonstrated favorable long-term outcomes for the IDH1-vac cohort. The 8-year progression-free survival rate was 0.42 months (confidence interval (CI): 0.24-0.59), and the overall survival (OS) rate was 0.66 months (CI: 0.46-0.79). A particularly significant finding was observed in participants with grade IV astrocytoma: > The median OS for grade IV astrocytoma patients receiving IDH1-vac was 106.1 months (CI: 39.6-not estimable (NE)), which compares favorably to published median OS rates for this population, typically ranging from 31.6-56.4 months. Sustained antibody responses to IDH1-R132H were strongly associated with a favorable long-term clinical course within the responder group. Furthermore, IDH1-vac-induced T cell responses were detected in the inflamed brain lesion of an IDH1-vac-associated pseudoprogression, whereas such T cells were notably absent in participants experiencing early progressive disease, suggesting a direct immunological mechanism of action.