Clinical trials have shown that an exploratory cancer drug from

Amgen

(AMGN) - Get Report

slows the progression of colorectal cancer in patients whose disease has spread to other parts of the body.

When given to patients who were previously treated for metastatic colorectal cancer in which chemotherapy didn't work, panitumumab, administered every two weeks, was found to be more effective than the best supportive care alone.

The late-stage trial involved 463 patients and the results were reviewed by an independent board looking at how the disease advanced, as well as tumor shrinkage.

After six months of treatment, about four times as many patients on panitumumab were alive and their disease didn't worsen compared with patients on the current best supportive care. After eight months, twice as many panitumumab patients were alive and progression-free in the phase III study.

The disease was controlled in 36% of patients taking the drug compared with 10% of patients treated with supportive care.

Phase III is the stage of clinical trials conducted just before the drug is submitted to the Food and Drug Administration for approval. The supportive care in the study consisted of treatments meant to ease the symptoms of cancer but didn't include chemotherapy.

Shares of Amgen were 41 cents lower at $72.34 Monday.

Amgen developed panitumumab with Abgenix, a company it acquired for $2.2 billion.