The same thing applies to colorectal cancer. Worldwide, about 1.2 million people develop this disease every year and it is the cause of death for an estimated 608,000 people per year. In Europe alone, there are 436,000 new cases annually and 212,000 deaths from this cancer. The prognosis is especially poor if the tumor was identified at a late stage and has already formed metastases. In addition to regular chemotherapy, treatment with new types of biotechnological pharmaceuticals are possible in cases such as this.
One of these pharmaceutical products is Erbitux®, a “monoclonal antibody”. This specially adapted protein molecule locates a specific receptor on somatic cells that regulates the growth of tumor cells in many intestinal-cancer patients. When it binds to that receptor, the growth of these tumor cells is inhibited. Normally, the receptor responds to the body’s own epidermal growth factor (EGF), and the cancer cells react to this by quickly multiplying uncontrollably. Erbitux® switches this “stimulator” off and can thereby greatly inhibit the progress of the disease.
This is not possible for all patients, however, as Professor Kirchner explains: “The signal of the EGF receptor is transmitted into the cell through several additional stages.” This is called a signal transduction pathway — it transmits the growth signal to the nucleus of the tumor cell that initiates cell division. One stage along this path is the RAS proteins. And the genes that provide the template according to which these proteins are formed in the patient’s body can likewise be changed by mutations: “In this case, Erbitux® cannot have its intended effect,” says the specialist. “As a result of the changed RAS genes, the signal path remains switched on without any interruption.”