Having just 86 patients enrolled makes the bavi study more difficult to interpret. A smaller study is also more susceptible to differences in baseline characteristics of patients, so it will be important to see whether there are any significant differences in the patients enrolled in each arm of the study.
The bavi study is open label, meaning doctors and patients know if they're receiving bavi plus chemo or chemo alone. Open-label studies are more prone to biased results unless data is independently verified.
Peregrine's phase II study is enrolling lung cancer patients at 17 hospitals in the U.S., nine sites in India and 14 sites in Eastern Europe and Russia, according to a
description of the study
on ClinicalTrials.gov. Avastin plus chemo is the standard-of-care treatment for front-line lung cancer in the U.S., so how is Peregrine managing to enroll U.S. patients in a study that excludes Avastin?
Says Peregrine: "Avastin is not indicated for all front-line NSCLC [non-small cell lung cancer] patients, per independent research a minority of patients are treated with Avastin."
Genentech tells me that 40% of eligible lung cancer patients are treated with Avastin. Technically, that's a minority of patients, but certainly a large minority. Perhaps Peregrine is seeking "Avastin intolerant" patients for its bavi study. The company wouldn't tell me, specifically.
Peregrine did say that patients enrolled in the bavi study are "well-represented from the U.S., Europe and Asia." Peregrine wouldn't provide me a geographic breakdown of enrolled patients. I'd certainly be interested in seeing the data from the study parsed by geography. For instance, higher response rates among Indian patients have been documented in previously published studies.
Peregrine will be reporting additional data from this phase II study of bavi in 2012, including progression-free survival and overall survival. That's good because response rate is not a meaningful endpoint in lung cancer studies from a regulatory standpoint. A search through previous published lung cancer studies finds that improvements in tumor response rate don't always correlate to a survival benefit. Ultimately, Peregrine needs to demonstrate a survival benefit with bavi if it wants to see the drug approved.