FDA panel approves drug to shrink breast cancer tumors pre-surgery

(CBS News) Doctors are calling the approval of a drug called Perjeta by a Food and Drug Administration advisory panel a historic moment in breast cancer treatment. The panel is approving the medication to shrink tumors before surgery in early-stage patients.

The move comes over a year after Perjeta was approved for late-stage patients. In 40 percent of the cases, it worked so well that surgeons couldn't find the tumor they planned to remove, according to the FDA.

CBS News contributor Dr. David Agus, who leads the Westside Cancer Center at the University of Southern California, is one of the first cancer doctors to use Perjeta.

"It's an exciting drug because it targets a particular pathway in the cancer -- an 'on' switch if you will. About 15,000 women a year have this very aggressive cancer with this 'on' switch (a molecule called HER-2) and it turns it off. So targeted therapy is generally less toxic and really can have a major impact on the cancer," Agus said on "CBS This Morning."

Drugs are classically tried on advanced patients, Agus said, because they are willing to tolerate the toxicity and they have no other choice because when cancer is advanced, doctors run out of treatments. "It classically takes eight to nine to 10 years after a drug is approved for advanced cancer until we start to move it early," he explained. "Well, the FDA had a major change. And they said, 'You don't need to show survival advantage before we'll consider the drug. You just have to show something mayor is happening.' And so, in this case, the tumor going away, that's pretty major. And so, we can now, a year after the drug is approved, get it for these patients. It's a major shift in policy. It's a major shift in thinking."

The "on" switch type of cancer that may benefit from this drug is found in about a third of breast cancer cases, Agus said.

"When it's there, it's classically aggressive and these tumors cause major problems," he said. "We used to do the surgery and then treat, wait for it to come back, and treat, and cancer is a disease that every time you treat, it gets more aggressive -- one of the few diseases that does so. So the argument is, let's switch and treat early because hopefully then we can make a major impact on this disease."

For more on this treatment and the potential impact of this FDA change on other treatments, watch Agus' full interview above.