Scientists point to an acquired mutation during treatment as the causative mechanism of therapeutic failure. This discovery leads to new perspectives to improve the efficiency of treatments, the survival of patients and to advance in customized treatments against cancer. Doctors and researchers of Hospital del Mar and its research institute, the IMIM, have led a study describing a new pharmacological resistance to cancer. This new mechanism is a mutation in an oncogene called EGFR (epidermal growth factor receptor) causing resistance to treatment using a drug called cetuximab, a monoclonal antibody which specifically attacks the EGFR. The study demonstrates that, both in lab models and in patients with colon cancer, this mutation appears during the disease and that, when this happens, it stops the drug from being effective so the tumor grows. This finding will benefit a large number of patients since colorectal cancer is the second most frequent tumor and cetuximab is a drug used regularly to treat this form of cancer. Colorectal cancer is the most frequent form of cancer in men and women and shows an increasing incidence, and is the main cause of death by cancer when studying the cases in male and female patients jointly. However, over the past decade, treatment has been revolutionized with the introduction of new chemotherapy drugs and treatments targeting cellular targets, such as monoclonal antibodies or drugs used to treat colorectal cancer. Dr. Joan Albanell, head of the Medical Oncologic service of Hospital del Mar and head of the research group and the author of the study, states that: "This new type of mutation reveals one of the causes why cancer therapy with monoclonal antibodies may cease to be effective at a given moment and, especially, opens the door to looking for solutions.