Impact of EGFR mutation on relapse pattern in glioblastoma.

BACKGROUND

Molecular factors influence relapse patterns in glioblastoma. The hotspot mutation located at position 289 of the extracellular domain of the epidermal growth factor receptor (EGFR) is associated with a more infiltrative phenotype. The primary objective of this study was to explore the impact of the EGFR mutation on the pattern of relapse after chemoradiotherapy-based treatment of patients suffering from newly diagnosed glioblastoma.

PATIENTS AND METHODS

An ancillary study from a prospective cohort of patients suffering from glioblastoma was conducted. All patients received radiotherapy and concomitant temozolomide. The population was divided into two groups according to EGFR status (mutated versus wild-type). The primary endpoint was the overlap score (varying from 0 to 1) between the initial irradiated tumor volume (Vinit) and the relapse volume (Vr). Secondary endpoints explored the impact of EGFR on survival.

RESULTS

One hundred twenty-eight patients were included and analyzed: 11% had EGFR glioblastoma (n = 14/128). EGFR glioblastomas had a relapse pattern that was more marginal than EGFR glioblastomas: a median overlap score Vinit/Vr of 0.96 was observed in the EGFR group versus 1 in the EGFR group (P = 0.05). Half of the population with EGFR tumor (n = 7/14) had a marginal relapse (i.e. overlap score ≤ 0.95) compared to 23.7% (n = 27/114) in the EGFR group, P = 0.035. EGFR did not influence survival.

CONCLUSION

We highlighted a link between the EGFR mutation and the relapse pattern in glioblastoma. The independent role of EGFR and its clinical implication should now be explored in further studies.