A Phase III study of DNA's Avastin found the drug to be effective in increasing the lifespan of breast cancer patients when combined with other pre-existing treatments.
Roche said it would buy the remaining 45 percent of the company it didn't already own for $43.7 billion, or $89 per share.
A study showed that patients treated with Avastin plus chemotherapy was 28 percent more effective in preventing the disease from getting worse than chemotherapy alone.
The rheumatoid arthritis drug Rituxan was no more effective than placebo in treating lupus, the results of a 52 week Phase II/III trial showed.
An FDA panel voted against recommending Avastin for breast cancer patients. The panel cited data that showed while the drug slowed the progression of cancer, it did not increase lifespan significantly. Stock price dipped by 9 percent to $66.20 during mid-day trading.