TUESDAY, June 28 (HealthDay News) -- The controversial cancer drug Avastin becomes the focus of U.S. regulators' attention again Tuesday during a two-day hearing to determine if the medication can keep its FDA approval for the treatment of metastatic breast cancer.

Back on Dec. 16, the U.S. Food and Drug Administration recommended revoking approval of the drug to fight breast cancer, citing the medication's poor performance in follow-up studies and its potential for serious side effects.

The drug's maker, Genentech, now owned by the pharmaceutical giant Roche, was given the chance to appeal the FDA recommendation and present additional evidence. That appeal will be the focus of the hearing and, according to published reports, will involve Genentech urging one more clinical trial before any government action on the drug.

The FDA's unusual step of scheduling another hearing on the drug underscores the difficulty of withdrawing approval of a cancer medication, the Associated Press reported.

"It says to me that either they [the FDA] have gotten a great deal of negative feedback from various quarters, or there's some kind of internal disagreement within the agency," Dr. Gary Lyman, professor at the Duke Cancer Institute in North Carolina, told the news service. Lyman was part of the FDA advisory panel that voted 12-1 last July to revoke Avastin's approval as a breast cancer therapy.

The FDA's December recommendation did not immediately affect breast cancer patients' access to the drug or limit use of Avastin (bevacizumab) for advanced colon, lung, kidney and brain cancer.

"FDA has taken the first step to removing the breast cancer indication from the label of the cancer drug Avastin," Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, announced at the Dec. 16 news conference. "This is a first step in a process and will not have an immediate impact on use of Avastin or the drug's availability."

"Oncologists currently treating patients with Avastin should use medical judgment in deciding whether to continue treatment or explore other treatment options," she added.

Some doctors expressed concern at the FDA's decision last December.

"This is a tough issue. There are women who have clearly responded to the treatment, [and] this is going to be a very difficult pill to swallow for those women," said Dr. Neil Spector, professor of medicine at the Duke Cancer Institute.

"There's a very real possibility that there may be a subgroup of women that are likely to respond to this," Spector said. "I don't think this will be the end from the standpoint of investigation and people trying to understand who that subpopulation is. It's just unfortunate that this will put a huge crimp in trying to figure that out."

Another expert, Dr. Julie Gralow, director of breast medical oncology at the Seattle Cancer Care Alliance (SCCA), called the FDA decision "disappointing."

"It is clear that some breast cancer patients derive substantial benefit from Avastin," Gralow, who is also professor in the Medical Oncology Division of the University of Washington School of Medicine, said in a SCAA press statement. "We don't know how to select those tumors or patients yet. It is looking like patient factors, not tumor factors, might be the best way to select those who benefit. To withhold this drug from all patients because some don't benefit is incorrect."

Doctors can continue to prescribe Avastin to patients "off-label," as they do other drugs. But it's unlikely that insurance companies would cover off-label use of the drug given its high price tag, Spector said. Avastin costs more than $8,000 a month, according to published reports.

The FDA last December did not rule out the possibility that if Avastin is actually revoked, approval could be restored for certain subgroups of patients who may benefit.

"FDA is ready to work with Genentech on any proposals to conduct additional studies in metastatic breast cancer designed to identify responsive tumors," Woodcock added at the time.

Avastin was OK'd in 2008 for use in conjunction with chemotherapy under the FDA's accelerated approval program. Approval was based on one clinical trial of patients with metastatic HER2-negative breast cancer that found a benefit in terms of cancer recurrence -- but not overall survival -- and was contingent on further data to confirm the results.

Three subsequent studies failed to find an overall survival benefit and, in fact, showed less impressive improvements in survival involving no progression of cancer.

After reviewing all four studies, FDA concluded that "patients receiving Avastin did not live any longer than patients not treated with the drug and were at greater risk of severe side effects, some of which are unique to Avastin," Woodcock said.

"These include perforations of the nose, stomach and intestine, many of which can be life-threatening, as well as high blood pressure, heart attack or heart failure, wound-healing complications and organ damage or failure," she said.

More information

The U.S. National Cancer Institute has more on Avastin.