Epidermal growth factor receptor (EGFR) amplification rates observed in screening patients for randomized trials in glioblastoma.

Purpose: Epidermal growth factor receptor (EGFR) amplification has been reported to occur in ~ 50% of glioblastomas (GBMs). We are conducting several global studies that require central testing for EGFR amplification during screening, representing an opportunity to confirm the frequency of amplification in GBM in a large cohort and to evaluate whether EGFR amplification differs by region of the world.

Methods: EGFR amplification was measured by fluorescence in situ hybridization during screening for therapeutic trials of an EGFR antibody-drug conjugate: two Phase 2/3 global trials (INTELLANCE-1, INTELLANCE-2), and a Japanese Phase 1/2 trial (INTELLANCE-J). We evaluated the proportion of tumor tissue samples harboring EGFR amplification among those tested and differences in amplification frequency by geography.

Results: EGFR was amplified in 54% of 3150 informative cases screened for INTELLANCE-1 and -2, consistent with historic controls, but was significantly lower in patients from Asia versus the rest of the world (35% vs. 56%, P < 0.0030). The independent INTELLANCE-J trial validated this finding (33% amplified of 153 informative cases).

Conclusions: EGFR amplification occurs less frequently in patients from Asia than elsewhere. Further study is required to understand biological differences to optimize treatment in glioblastoma.