Following the sudden death of four patients for reasons unrelated to cancer, Genentech and its majority stakeholder Roche decided to stop enrolling new patients in a large clinical trial involving cancer drug Avastin.Roche said there have been seven total deaths since the trial of Avastin started in 2004, but the four who died suddenly prompted it to temporarily suspend enrollment while experts review additional safety data.According to the San Jose Mercury News, analysts are optimistic the deaths won’t immediately affect the companies’ finances because it’s too early to know what caused them.The fatalities came during a trial in which Avastin was used along with a chemotherapy regimen called XELOX, to test whether Avastin can safely be used to prevent colon cancer from recurring in patients in remission.Overall there were seven non-cancer-related deaths in the Avastin/XELOX group, two of heart trouble. The cause of death of three remains unknown, and Genentech said it had no data on the other two patients.Four deaths came in another arm of the study that combined Avastin with a different chemotherapy regimen, FOLFOX.Avastin, which was approved for patients with advanced colon cancer in 2004, had 2005 sales of $1.1 billion.