Amgen's Vectibix performs well in cancer study

* 1.6-month benefit for progression free survival

* Vectibix is challenger for colon cancer drug Erbitux

BERLIN, Sept 21 (Reuters) - Amgen's (AMGN.O) colon cancer drug Vectibix showed a 20 percent reduction in the risk of disease progressing in a clinical study, according to a scientific abstract from Europe's top cancer meeting.

Vectibix demonstrated a 1.6-month benefit for progression-free survival in patients with an unmutated form of a gene in the Phase III study, known as PRIME, a result JP Morgan analyst Alexandra Hauber said was "impressive".

The findings will be reported in full at the ECCO-ESMO cancer conference in Berlin on Thursday.

Erbitux, discovered by ImClone which is now part of Eli Lilly (LLY.N) and is sold by Merck KGaA (MRCG.DE) and Bristol-Myers Squibb (BMY.N), currently dominates the so-called anti-EGFR market. It had 2008 sales of $1.6 billion -- 10 times more than Amgen's (AMGN.O) Vectibix.

But Amgen hopes to redress this imbalance by showing its drug is similarly effective, while offering dosing advantages.

Both drugs have recently been found to work only in the 60 to 65 percent of patients whose tumours contain the normal, or wild-type, version of a gene known as KRAS.

In the PRIME study, those with KRAS mutations actually did worse than people on standard care, underlining the need for early genetic testing of patients. (Reporting by Ben Hirschler; Editing by David Holmes)