A Phase III study of ImClone System’s Erbitux has met its primary endpoint in patients with previously untreated metastatic colorectal cancer.

The CRYSTAL study, which was carried out by ImClone’s licensing partner in Europe, Merck KGaA, showed that Erbitux (cetuximab) plus irinotecan-based therapy met the primary endpoint of increasing median duration of progression-free survival in patients with previously untreated metastatic colorectal cancer compared with chemotherapy alone.

In the 1,000 patient-strong randomised trial, patients received an initial dose of Erbitux (400mg/m2) followed by a weekly dose of the drug (250mg/m2), and chemotherapy, while the second arm received chemotherapy alone.

The fact that the trial has demonstrated the benefit of adding Erbitux to chemotherapy in first-line treatment is a huge boost for Merck, ImClone and the latter’s US partner Bristol-Myers Squibb. In terms of this indication (Erbitux is also used to treat head and neck cancers), the drug is currently only approved to treat colorectal cancer in combination with chemotherapy in patients who have failed other therapies and to get backing from the US Food and Drug Administration as a first-line treatment would open up a much larger market.

The news is particularly welcome given that Erbitux was unable to improve overall survival when used as a second-line treatment for metastatic colorectal cancer in data recently presented from the Phase III EPIC trial, although a second study looking at its use as a third-line therapy did meet that objective.

If the drug’s labelling is expanded, Erbitux would eventually go up in the lucrative first-line treatment arena against Amgen’s Vectibix (panitumumab), which received US Food and Drug Administration approval for third-line monotherapy use last September.