Introduction
Organoid technology has recently revolutionized research in hepatic oncology. Approaching drug resistance is essential to meet current clinical needs, particularly in hepatocellular carcinoma (HCC) and liver-metastatic colorectal cancer (mCRC). Standard-of-care (SoC) treatments are sorafenib for HCC and cetuximab for mCRC and have shown potent antitumor activity. However, resistance frequently develops, leaving patients with limited therapeutic alternatives. In the case of mCRC, mutations affecting the extracellular domain of EGFR determine its interaction with cetuximab, as it has been described with S468R. However, other clinically reported variants like G465R/E or S464L remain to be functionally characterized. To address this gap, the project LIVERtera integrates computational modeling to predict the functional impact of EGFR mutations, evaluate the ADME properties of sorafenib and identify novel active compounds against both malignancies.
Methods
Patient-derived organoids (PDOs) were established from HCC and mCRC tumor resections as well as matched normal adjacent tissue (NAT). A histological characterization of the tissue of origin was performed using hematoxylin and eosin staining. In parallel, the in silico study started by generating EGFR mutated residues by means of chemoinformatic tools to establish the systems. Next, potential steric impediments (clashes) between cetuximab and the interface surface area of EGFR were evaluated by quantifying changes in hydrogen bonds, hydrophobic interactions and Van Der Waals contacts.
Results
We observed that S468R abolished hydrogen bond formation, generating steric impediments with T47 and Y104 residues of the cetuximab light chain (chain C). G465R induced intramolecular steric impediments with K443 and intramolecular clashes with residues W52 and D58 of the cetuximab light chain. G465E generated an intramolecular clash with S418 and an additional clash with residue W52 of cetuximab light chain. Additional interactions such as cationic and π-stacking were mapped and, interestingly, an unexpected increase in events was observed in the cetuximab light chain, possibly representing artifacts of residue mutations.
Conclusion
In conclusion, our study identifies novel atomic-level interactions between EGFR and cetuximab that underlie resistance mechanisms, consistent with similar findings in the literature. Future work will focus on screening candidate compounds to overcome these clashes and evaluating sorafenib’s ADME profile in functionally characterized PDOs.
