Circulating tumour DNA analysis and new uses of anti-EGFR monoclonal antibodies in patients with metastatic colorectal cancer

Abstract

Currently, tumour tissue biopsy to determine RAS/BRAF gene alterations, assess microsatellite instability status, and determine HER‑2/neu gene amplification/hyperexpression is the gold standard of diagnosis and allows the selection of optimal molecularly targeted therapy when considering treatment strategies for patients with metastatic colorectal cancer. However, biopsy does not fully reflect the existing intratumoural heterogeneity and clonal evolution of tumour cells, which can often be the cause of therapeutic failures. In recent years, liquid biopsy has attracted increasing attention as an additional and potentially alternative non-invasive tool for molecular tumour profiling. Assessment of circulating tumour DNA allows changes in the genetic status of the tumour to be monitored and the «burden» of disease to be measured dynamically in real time. Advances in liquid biopsy technology have led to promising new strategies for the management of patients with metastatic colorectal cancer in late-line therapy. The standard drug arsenal in this group of patients is limited to either repeat administration of previously effective therapy or regorafenib and the combination of trifluridine/tipiracil with bevacizumab, which are characterized by limited clinical activity. However, thanks to the discovery of the NeoRAS wild-type phenomenon and the rechallenge strategy of anti-EGFR monoclonal antibodies based on the study of clonal selection and evolution of tumour cells, the administration of epidermal growth factor inhibitors in a molecularly selected by liquid biopsy population is accompanied by good tolerability and efficacy. Numerous clinical studies are ongoing to further understand the mechanisms of tumour resistance and to develop new evidence-based treatment approaches in order to realise the concept of personalised medicine.