The European Medicines Agency, based in London, has approved the use of Erbitux, produced by Merck KGaA, as a first line treatment against colorectal cancer that has spread in the patient’s body.

The German company, which distributes the medicine in Europe and has licensed it from ImClone Systems Inc, has stated that Erbitux works best with patients that have a Kras non-mutated, or wild-type, tumor.

The reason for this lies in the way Erbitux works. The medicine blocks a protein called epidermal growth factor, that is supposed to be one of the reasons for which cancer cells multiply. The Kras gene controls the way the epidermal growth factor works. If Kras is non-mutated, then Erbitux can work at its highest potential, if not, the treatment could prove less efficient.

The medicine is used together with chemotherapy, and studies have shown that if this combined treatment is used, there are more chances for patients to get better than in the case of chemotherapy treatment alone.

Merck KGaA had an income of $727 million from Erbitux alone. The medicine’s competitor is Avastin, which is produced by Roche Holding AG.

Merck will have to change the labels of its product so they will reflect the fact that the medicine works better for patients with wild-type Kras, whose numbers amount to 65 percent of the people who have colon cancer.

Erbitux is used as a fairly good remedy for patients who have head or neck tumors as well.