Some of the most surprising data presented at the GI Symposium in January 2011 in San Francisco was the negative result of the European trial called AVANT.
In that clinical trial patients who underwent a curative resection for colon cancer received either FOLFOX or FOLFOX with Avastin® (bevacizumab) treatment after their surgery. Chemotherapy was given over 6 months, but patients who were randomly selected for Avastin received 6 months with chemotherapy and additional 6 months alone after chemotherapy ended for a total of 12 months of Avastin.
In our annual ASCO meeting in Chicago in 2009, we heard the results of an American trial (C-08) showing no benefit in patients who received Avastin in this setting, however there an interesting finding that during the 12 months Avastin was given there was a potential benefit. The European AVANT trial showed very similar results. Avastin did not improve outcome in patients who underwent a successful surgery for their colon cancer. There was again a hint of benefit during the time of Avastin therapy.
What does this all mean? After the negative data with Erbitux® and now with Avastin, we are coming to understand that drugs which work for metastatic disease may not have the same effect in patients who have only microscopic disease. The way these drugs work may be completely different if there only cells left or a tumor which has different infrastructure such as its own blood vessels and has overcome the defense of the immune system.
We need to get smarter and develop specific therapies for these patients and find out why the tumors in these patients come back. What makes colon cancer cells survive in some patients? How do some patients kill left over colon cancer cells?
We are back to the drawing board going beyond the pathology report to make treatment decisions but needing to understand the genetic make up of these cancers.