Genentech Data Bring Jitters

While positive, these results aren't likely to persuade doctors to use more Avastin with their kidney cancer patients. By comparison, Pfizer's Sutent, used by itself, boosted progression-free survival to 11.8 months compared with 6.2 months for interferon alone.

Sutent is now considered the first-line standard of care for kidney cancer patients, with Onyx's Nexavar being used once patients' tumors start growing again, or in patients who can't tolerate Sutent.

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Lastly, there's the data from Regeneron's VEGF-Trap. This drug -- which works by cutting off the blood supply to tumors -- has been the focus of much investor attention because of its potential as a potent Avastin competitor.

Regeneron enrolled 162 patients with advanced ovarian cancer that was resistant to chemotherapy. Patients were then randomized to receive one of two doses of VEGF-Trap.

Preliminary results from 153 patients from both dosage groups found that tumors shrank in 8% of patients. Tumors stopped growing in another 71% of patients. On the safety side, 1% of patients experienced perforations in their bowel, a potentially fatal side effect.

An 8% response rate to a drug in this patient group is positive, but the VEGF-Trap data does not surpass similar data from Avastin presented last year. In that study, Avastin produced a 16% rate of tumor shrinkage.