Histone H3.3 G34-mutant Diffuse Gliomas in Adults

The characteristics of H3.3 G34-mutant gliomas in adults have yet to be specifically described. Thirty adults with H3.3 G34-mutant diffuse gliomas were retrospectively reviewed for clinical and pathologic information. Molecular profiling using next-generation sequencing was performed in 29 of the 30 H3.3 G34-mutant patients with 1 patient lacking available tumor samples, as well as 82 IDH/H3 wild-type adult diffuse glioma patients. The age at diagnosis of H3.3 G34-mutant diffuse gliomas was significantly younger than IDH/H3 wild-type gliomas (24 vs. 57 y, P< 0.001). Overall, 19 of the 30 patients were diagnosed of glioblastoma with the primitive neuronal component, and 8 were glioblastoma. The molecular profiling analysis revealed higher frequencies of Olig-2 loss of expression, TP53 mutation, ATRX mutation, PDGFRA mutation, and MGMT promoter methylation (P < 0.05) in H3.3 G34-mutant gliomas than IDH/H3 wild-type gliomas. No TERT promoter mutation and only 1 case of EGFR amplification were detected in the H3.3 G34-mutant cohort, the frequencies of which were significantly higher in the IDH/H3 wild-type cohort. A dismal prognosis was observed in H3.3 G34-mutant patients comparing to IDH/H3 wild-type cohort (overall survival: 14 vs. 22 mo; P = 0.026). Univariate and multivariate analyses showed that the extent of resection and TP53 mutation were independently affecting prognosis. The distinct pathologic and molecular features of H3.3 G34-mutant diffuse gliomas in adult patients demonstrated the clinical importance of detecting H3.3 G34R/V mutations. The dismal prognosis of this rare high-grade glioma disease we reported here would further promote the investigation of dedicated therapeutic strategies.

Automated summary

This study retrospectively reviewed the clinical and pathological information of 30 adults with H3.3 G34-mutant gliomas. Compared to IDH/H3 wild-type gliomas, H3.3 G34-mutant gliomas were diagnosed at a younger age, had a worse prognosis, and exhibited different molecular features.