Amgen has announced results from a pivotal trial that show significantly improved survival rates for patients suffering from KRAS wild-type metastatic colorectal cancer after treatment with Vectibix (panitumumab).

Patients treated with Vectibix, administered in combination with FOLFOX (an oxaliplatin-based chemotherapy) showed significantly prolonged progression-free survival (PFS) compared with FOLFOX alone.

Amgen executive vice-president of research and development Roger M Perlmutter said that this is the first prospective Phase III data to demonstrate the utility of KRAS mutational analysis as a predictive biomarker.

“We believe that these data document an important advance for patients with metastatic colorectal cancer,” Perlmutter said.

The panitumumab randomised trial enrolled 1,183 patients globally. The primary endpoint of the study was PFS, as well as secondary endpoints including overall survival, objective response rate, time to progression, duration of response and safety.

Importantly, in patients with tumours harbouring activating KRAS mutations, PFS was significantly inferior in the Vectibix arm. These data confirm previous findings when oxaliplatin-based chemotherapy and an anti-EGFR antibody are combined.

The study was amended to analyse outcomes with respect to the presence or absence of activating mutations in KRAS in the tumour itself, instead of in the overall population.

Tumour KRAS status was ascertained in more than 90% of the 1,183 patients enrolled in the trial.