Failed Avastin early-stage cancer study detailed

By Deena Beasley

ORLANDO, Florida (Reuters) - A study of blockbuster drug Avastin in colon cancer patients who have undergone surgery showed that the drug's effectiveness wore off after patients stopped taking it, researchers said on Saturday.

As previously disclosed by the drug's maker, Roche Holding AG's Genentech unit, the 2,710-patient trial did not meet its main goal of showing an extension in disease-free survival.

Newly released details show that 77.4 percent of patients in the Avastin group were alive and free of disease after a median follow-up of three years, compared with 75.5 percent of patients in the control group, a difference that was not statistically significant.

But at the one-year mark, Avastin was shown to reduce the risk of cancer recurrence or death by about 40 percent. This result proves that the drug is active in early-stage cancer, said Phillippe Bishop, head of clinical development for Avastin at Genentech.

The trial was designed to show whether use of Avastin plus chemotherapy for six months, followed by six months of Avastin alone, results in more patients being cancer free after three years compared with just treating them with chemotherapy.

"As patients come off treatment, the events come back," Bishop said. "The one-year duration of treatment was insufficient to derive clinical benefit."

This was the first trial which sought to show Avastin's ability to prevent cancer recurrence by wiping out microscopic cancer cells that may remain in the body after tumors have been removed by surgery, known as use in the "adjuvant" setting. But several similar trials are under way, including a second in early-stage colon cancer patients for which results are expected next year.

Since all of the current adjuvant trials of Avastin also have treatment durations of one year, there is little expectation that results will be encouraging.