A multicenter, phase II trial of GC1118, a novel anti-EGFR antibody, for recurrent glioblastoma patients with EGFR amplification

Background: We evaluated the therapeutic efficacy of GC1118, a novel anti-epidermal growth factor receptor (EGFR) monoclonal antibody, in recurrent glioblastoma (GBM) patients with EGFR amplification. Methods: This study was a multicenter, open-label, single-arm phase II trial. Recurrent GBM patients with EGFR amplification were eligible: EGFR amplification was determined using fluorescence in situ hybridization analysis when a sample had both the EGFR/CEP7 ratio of ≥2 and a tight cluster EGFR signal in ≥10% of recorded cells. GC1118 was administered intravenously at a dose of 4 mg/kg once weekly. The primary endpoint was the 6-month progression-free survival rate (PFS6). Next-generation sequencing was performed to investigate the molecular biomarkers related to the response to GC1118. Results: Between April 2018 and December 2020, 21 patients were enrolled in the study and received GC1118 treatment. Eighteen patients were eligible for efficacy analysis. The PFS6 was 5.6% (95% confidence interval, 0.3%–25.8%, Wilson method). The median progression-free survival was 1.7 months (range: 28 days–7.2 months) and median overall survival was 5.7 months (range: 2–22.0 months). GC1118 was well tolerated except skin toxicities. Skin rash was the most frequent adverse event and four patients experienced Grade 3 skin-related toxicity. Genomic analysis revealed that the immune-related signatures were upregulated in patients with tumor regression. Conclusion: This study did not meet the primary endpoint (PFS6); however, we found that immune signatures were significantly upregulated in the tumors with regression upon GC1118 therapy, which signifies the potential of immune-mediated antitumor efficacy of GC1118.