Cetuximab-Mediated Protection from Hypoxia- Induced Cell Death: Implications for Therapy Sequence in Colorectal Cancer

Abstract

Monoclonal antibodies like cetuximab, targeting the epidermal growth factor receptor (EGFR), and bevacizumab, targeting the vascular endothelial growth factor (VEGF), are an integral part of treatment regimens for metastasized colorectal cancer. However, inhibition of the EGFR has been shown to protect human glioma cells from cell death under hypoxic conditions. In colon carcinoma cells, the consequences of EGFR blockade in hypoxia (e.g., induced by bevacizumab) have not been evaluated yet. LIM1215 and SW948 colon carcinoma and LNT-229 glioblastoma cells were treated with cetuximab, PD153035, and erlotinib and analyzed for cell density and viability. The sequential administration of either cetuximab followed by bevacizumab (CET->BEV) or bevacizumab followed by cetuximab (BEV->CET) was investigated in a LIM1215 (KRAS wildtype) and SW948 (KRAS mutant) xenograft mouse model. In vitro, cetuximab protected from hypoxia. In the LIM1215 model, a survival benefit with cetuximab and bevacizumab monotherapy was observed, but only the sequence CET->BEV showed an additional benefit. This effect was confirmed in the SW948 model. Our observations support the hypothesis that bevacizumab modulates the tumor microenvironment (e.g., by inducing hypoxia) where cetuximab could trigger protective effects when administered later on. The sequence CET->BEV therefore seems to be superior as possible mutual adverse effects are bypassed.

A Long-Term and Large-Scale Real-World Study in Taiwan: Efficacy of Target Therapy in Stage IV Colorectal Cancer

“…PFS1 was comparable (10.0 vs 10.4 months; P =0.402), while PFS2 (4.6 vs 7.9 months; P =0.002), OS1 (26.8 vs 40.0 months; P =0.011), and OS2 (15.2 vs 22.3 months; P =0.006) were reduced in Group A compared with Group B. A recent in-vitro study ( 19 ) compared the sequential administration of either cetuximab followed by bevacizumab (CET-BEV) or bevacizumab followed by cetuximab (BEV-CET) in a LIM1215 (KRAS wild type) and SW948 (KRAS mutant) xenograft mouse model. These results suggest that bevacizumab may act through the modulation of the tumor microenvironment by inducing hypoxia and cetuximab administration prior to bevacizumzb could trigger protective effects.…”