New data presented at the 2009 American Society of Clinical Oncology Gastrointestinal Cancers Symposium (ASCO GI) in San Francisco add further evidence to the enhanced efficacy of Erbitux (cetuximab) in metastatic colorectal cancer (mCRC) patients with kras wild-type tumours.

The CECOGa/CORE1.2.001 study, a randomized phase-II trial investigating the influence of kras status on the efficacy of Erbitux in combination with Folfox or Folfiri in the 1st-line treatment of 117 mCRC patients, provided a response rate (RR) of 53 per cent in patients with kras wild-type tumours versus 36 per cent in those with mutant tumours. The study also showed a trend towards improved overall survival (OS) in patients with kras wild-type tumours - 24.4 months for patients with kras wild-type tumours vs. 16.7 months for patients with kras mutant tumours (p=0.057).1

"It is really exciting to see such a consistent efficacy profile for Erbitux in patient populations defined by kras mutational status," commented professor Thomas Brodowicz from the University Hospital of Vienna, Austria, lead investigator of the CECOG/CORE1.2.001 study. "This further highlights the absolute necessity to define mCRC according to the kras status of the tumour in order to determine the most effective treatment strategy and to provide patients with the best possible outcomes."

The results of the CECOG/CORE1.2.001 study support the pivotal Erbitux trials - the randomized phase-III study CrystalB, also presented at this meeting, and OPUSc, recently published in the Journal of Clinical Oncology. The outcomes of the randomized CELIMd trial, also presented at ASCO GI, further support the data presented from the Crystal and CECOG/CORE1.2.001 studies, which showed that the addition of Erbitux to standard chemotherapy in patients with unresectable liver metastases leads to high response rates. In the CELIM study, 79 per cent of patients with kras wild-type tumours experienced distinct tumour shrinkage, and of these patients, 42 per cent were able to undergo surgical resection and 35% were able to have the tumour completely removed (R0 resection).4

"The data demonstrating the efficacy of Erbitux in kras wild-type mCRC tumours are really mounting up now and for physicians this can only help ease the treatment decision-making process," commented Dr Wolfgang Wein, executive vice president, Oncology, Merck Serono. "Tailoring treatment for mCRC is now a reality. Through a simple diagnostic test, patients can be provided with a treatment that is most likely to succeed in their tumour type."

Erbitux is a first-in-class and highly active IgG1 monoclonal antibody targeting the epidermal growth factor receptor (EGFR).

kras is a gene that codes for a protein that plays an important role in the epidermal growth factor receptor (EGFR) pathway - a complex signalling cascade that is involved in the development and progression of cancer.