Michael J. Birrer, MD, PhD, director, Massachusetts General Hospital Cancer Center, gynecologic medical oncology, discusses the GOG0218 and the ICON7 trials, which added bevacizumab to standard chemotherapy in the first-line and maintenance setting for patients with ovarian cancer. These trials were recently published in the New England Journal of Medicine and have caused controversy in regards to the efficacy of bevacizumab (Avastin) to treat ovarian cancer.

These studies concluded that the addition of bevacizumab prolonged progression-free survival (PFS) but did not significantly extend overall survival (OS). GOG0218 was an 1873-patient study that demonstrated an improvement in PFS of 3.8 months. ICON7 enrolled 1528 women with a 1.5-month increase in PFS.

The time needed to accurately calculated OS has not yet been reach for these trials, but early indications show that they did not significantly improve OS. Birrer notes that the FDA has made it clear that they will not approve new drugs for ovarian cancer based on PFS alone. An OS benefit must be demonstrated to gain approval, which he believes neither of these trials will demonstrate, due in part to the design of the trials.

In the GOG0218 trial Birrer estimates the crossover rate to be higher than 30-50%. Out of the patients that received placebo many did not receive bevacizumab until they had progressed. This high-level of crossover makes the OS endpoint difficult to achieve, which was the secondary endpoint for this trial.

The ICON7 trial is easier to gauge because it was conducted in Europe, where bevacizumab is difficult to receive outside of trials, this made crossover more difficult. OS was the primary endpoint in this trial, which cannot be accurately calculated until 2013.

Read more >>> Avastin Increases PFS in Patients With Ovarian Cancer.