AMG-510 Plus Cetuximab Enhance Radiosensitivity in KRAS p.G12C Mutant Colorectal Carcinoma Cell Lines via Increasing Apoptosis and Inducing G1/S Arrest

Abstract

<h3>Purpose/Objective(s)</h3> KRAS p.G12C mutation is rare (∼3%) but with a dismal prognosis in colorectal carcinoma (CRC). AMG-510 is a first-in-class KRAS p.G12C inhibitor, which shows clinical efficacy in KRAS p.G12C mutant solid tumors including non-small cell lung cancer and CRC. The addition of cetuximab could revert resistance to AMG-510 in CRC. Herein, we evaluate the anti-cancer effect of AMG-510 plus cetuximab in combination with radiation in CRC. <h3>Materials/Methods</h3> Two KRAS p.G12C mutant CRC cell lines were treated with AMG-510, AMG-510 plus cetuximab, irradiation (IR), and the combination of IR and AMG-510 plus cetuximab. Clonogenic assays were used to study the radiosensitizing effect of AMG-510 combined with cetuximab. Immunofluorescence staining of rH2AX was used to detect double-strand break (DSB) repair. Cell proliferation was performed using a cell counting kit. Then, we performed flow cytometry analysis to detect cell apoptosis rate and cell cycle distribution. <h3>Results</h3> First, we found that AMG-510 plus cetuximab enhanced the radiosensitivity of X-ray in the SW837 cell line (sensitization enhancement ratio: 1.32). The combination of AMG-510 and cetuximab reduced cell proliferation and increased cell apoptosis rate and DNA damage, with or without irradiation. The flow cytometry analysis of the cell cycle showed G1/S phase arrest after AMG-510 monotherapy and AMG-510 plus cetuximab treatment. Moreover, the P53/Rb/P21 pathway was activated after the addition of AMG-510 with or without cetuximab. <h3>Conclusion</h3> The combination of AMG-510 and cetuximab might be a potent treatment as a radiosensitizer. However, more studies in vivo and clinical trials should be performed to further evaluate this regimen in the future.