Loss of PTEN expression predicts resistance to EGFR-targeted monoclonal antibodies in patients with metastatic colorectal cancer

Sir, Phosphatase, homologue to tensin (PTEN), is a tumour suppressor protein that regulates the PI3K/AKT signalling pathway.Loss of PTEN expression results in overactivation of the Akt pathway and confers resistance to inhibitors of the epidermal growth factor receptor (EGFR).Recently, four clinical studies have evaluated the association between PTEN expression status and response to the treatment of EGFR-targeted monoclonal antibodies (cetuximab