Impact of 10q loss, CDKN2A deletions, EGFR amplification, and trisomy of chromosome 7 in the overall survival of IDH-mutant astrocytoma

Abstract

Introduction: Since progression from grade 2 to grade 4 occurs in the evolution of IDH-mutant astrocytoma (A, IDH-mut), it is crucial to identify the key factors that define the different grades.

Aims: To evaluate the impact on overall survival (OS) of molecular alterations traditionally associated with high-grade gliomas within the grading scheme.

Materials and methods: We retrospectively analyzed the role of 10q loss, CDKN2A deletions, EGFR amplification (Amp), and trisomy of chromosome 7 (trisomy 7) in 189 A, IDH-mut, reclassified according to the WHO 2021 criteria (grade 2, n = 133; grade 3, n = 18; grade 4, n = 38).

Results: Among the 189 cases, 29 presented with CDKN2A hemizygous deletion (hemidel), 17 with CDKN2A homozygous deletion, 18 showed trisomy 7, and 2 showed EGFR Amp. A multivariate test revealed that WHO grade 4 and trisomy 7 significantly impacted OS. CDKN2A hemidel and 10q loss did not influence OS in our cohort. Given that 11 out of 18 cases with trisomy 7 were IDH-mutant grade 2 (G2), we compared G2 cases with and without trisomy 7 and found worse OS in cases with trisomy (p = 0.0034), similar to WHO grade 4.

Conclusion: Our results suggest that trisomy 7 plays a significant role in the OS of A, IDH-mut. Further research is needed to determine whether trisomy 7 is an independent marker or if it is associated with other molecular alterations that affect OS.