Genentech says that a late-stage clinical trial will continue of its blockbuster Avastin plus chemotherapy in patients with early-stage colon cancer.

The company noted that the decision to carry on with the Phase III study, which is being conducted by the US National Surgical Adjuvant Breast and Bowel Project, comes after a recommendation from an independent data monitoring committee after a planned interim analysis. Full results from the study, which involves 2,710 patients, and evaluates the effect of Folfox (5-fluorouracil, leucovorin and oxaliplatin) chemotherapy with or without Avastin (bevacizumab) on disease-free survival in patients with resected Stage II or III adenocarcinoma of the colon, are now expected in mid-2009.

Interim safety data presented earlier this year had shown side effects including hypertension, wound-healing complications and pain occurred more often in patients receiving Avastin than those receiving chemotherapy alone. However the decision to carry on with the study is a major boost for Genenetech.

Avastin is approved as a treatment for patients with colon, lung and breast cancers and third-quarter US sales of the drug rose 18% to $704 million. However, adjuvant use of Avastin in patients undergoing successful colon cancer resection surgery could add at least another $5 billion in annual sales, according to an estimate from analysts at Cowen & Co.

News of the trial could led to Roche upping its initial $89-a-share offer for the rest of Genentech it does not already own, some analysts have said. That offer was widely considered to be too low and did not reflect the huge commercial potential for Avastin adjuvant therapy.