* FDA staff cites issues with Genentech’s Avastin data
* Genentech says data support use of drug for brain cancer
* FDA advisory panel to review possible new use Tuesday
* Company expects FDA final approval decision May 5 (Adds comments from company, FDA, updates shares)
By Susan Heavey
WASHINGTON, March 27 (Reuters) - It is difficult to tell how well brain cancer patients responded to Genentech Inc’s cancer drug Avastin in early studies from the company, U.S. Food and Drug Administration staff said in documents released on Friday.
In patients who saw an effect on their tumors, it was also unclear whether that was from Avastin or other factors, the staff said, adding that the FDA would seek advice from its panel of outside experts.
The documents were released ahead of the advisory panel’s meeting on Tuesday.
Genentech, now part of Roche ROG.VX, is seeking accelerated U.S. approval to market its drug more widely for brain cancer patients with glioblastoma, an especially deadly tumor, who have already received other treatment. Avastin, also known as bevacizumab, is approved for lung, colon and breast cancers.
Malignant brain tumors are one of the deadliest types of cancer. They are getting more public attention since Senator Edward Kennedy was found to have a brain tumor last year. Patients, on average, survive six to 12 months after diagnosis, or six months without treatment.
Glioblastomas are the most aggressive type of brain tumor, killing about 10,000 people each year. Other treatments include chemotherapy and radiation.
In separate documents released on Friday, Genentech said its data showed improvements in patients with brain cancer and that it was starting a larger study that would offer more information in 2014.
“There are no effective FDA-approved systemic therapies for patients with previously treated glioblastoma, and there have been virtually no improvements since the 1970s,” it said.
Avastin is a type of anti-angiogenic drug that restricts the rapid growth of blood vessels that spur tumor growth.
One study of 167 patients found a median duration of response rate of 4.2 months among those who saw a tumor reduced, while a second study of 56 patients found a median response duration of 3.9 months, according to the FDA.
The FDA said it was “unclear” whether the patients’ responses were sufficient enough to warrant accelerated approval.
The most common side-effects were fatigue, headache and hypertension, although none seemed significant, the FDA said.
The agency will weigh the advice of its outside experts before making its final decision, which the company said it expects by May 5.
Avastin had U.S. net sales of $2.7 billion in 2008. Some 19,000 cases of brain tumors are diagnosed each year, the company has said, citing government statistics.
Shares of Roche, which completed its acquisition of Genentech on Thursday, closed up 2.6 percent on the Swiss market. (Reporting by Susan Heavey; Editing by Dave Zimmerman)