Retreatment With Anti-EGFR Antibodies in Metastatic Colorectal Cancer Patients : A Multi-institutional Analysis

Background: On the basis of retrospective analyses and phase 2 studies, metastatic colorectal cancer patients whose disease responded to a first-line regimen containing an anti-epidermal growth factor receptor (EGFR) agent may experience benefit from anti-EGFR readministration in later therapy lines. While the analysis of circulating tumor DNA seems a promising tool to select the best candidates for this strategy, identifying clinical predictors of anti-EGFR sensitivity would be useful to drive treatment choices in daily practice. Patients and methods: A real-life database of 5530 patients treated at 6 institutions was queried. Included were patients who were retreated with anti-EGFRs, who had RAS/BRAF wild-type-status tissue samples, who had received a first-line anti-EGFR-based regimen with at least stable disease as best response, and who had received at least one further line of therapy before anti-EGFR retreatment. The association with overall response rate (ORR), progression-free survival (PFS), and overall survival (OS) of variables potentially related to anti-EGFR sensitivity was investigated. Results: A total of 86 patients were identified. The ORR during anti-EGFR retreatment was 19.8%; median PFS and OS were 3.8 and 10.2 months, respectively. No significant association of clinical features of anti-EGFR sensitivity with ORR, PFS, and OS was observed. Among the 56 patients with a time from the last anti-EGFR administration to first-line progressive disease of < 3 months (rechallenge group), > 2 prior therapy lines and a longer anti-EGFR-free interval were associated with higher ORR, but not with longer PFS or OS. Conclusion: Clinical features we deemed surrogates of anti-EGFR sensitivity were not reliable predictors of benefit from anti-EGFR retreatment.