The US Food and Drug Administration approved a new drug to shrink breast tumors before surgery. While oncologists sometimes use chemotherapy to treat certain breast cancers before surgery, the new drug—called Perjeta (pertuzumab)—was the first to be approved specifically for this purpose in patients with early stage breast cancers that respond to the HER2 protein.
Perjeta was approved last year to treat metastatic HER-2 positive breast cancer, but so far it’s only been tested before surgery in those with early breast cancers that haven’t spread. In a trial of 417 breast cancer patients who received Perjeta along with a combination of other drugs over two months, 39 percent had their tumor completely disappear before surgery compared to 21 percent who took the standard combination of drugs.
Those promising findings alone were enough to convince the agency to approve Perjeta to use pre-operatively, despite a lack of data showing that women live longer when treated with the new regimen.
“An assumption is being made that improving the percentage of women who have complete tumor shrinkrage before surgery will improve their cure rates, but so far that assumption hasn’t held true for other drugs with few exceptions like trastuzumab [Herceptin],” said Dr. Ian Krop, a breast oncologist at the Susan F. Smith Center for Women’s Cancers at Dana-Farber Cancer Institute.
The FDA is awaiting results from a trial of more than 4,800 breast cancer patients who were treated with Perjeta, Herceptin, and other drugs after surgery to remove their tumors and who are being followed for several years to determine whether they have fewer recurrences and longer survival than those treated with a Herceptin regimen that doesn’t include Perjeta. Those results are expected in 2016.
“If we find out Perjeta doesn’t increase survival, then it should be taken off market for early stage cancers,” said Krop who is helping to conduct the long term trials. “I think this is a good test case for the FDA,” he added, since the drug had a significant impact on shrinking tumors before surgery and since it didn’t cause dangerous side effects beyond the usual ones from chemotherapy like hair loss, nausea, and immune system suppression.
Perjeta costs about $6000 a dose, and four doses are given before surgery over a period nine weeks.
Positive results from followup studies could also make it easier for other new cancer drugs to be fast-tracked for approval using pre-surgical tumor shrinkage to measure effectiveness.
It took seven years for Herceptin to move from a drug approved only for terminal breast cancer patients to one used in early stage patients with HER2-positive tumors because it was tested in trials that required long-term followup to measure survival benefits. It took Perjeta only one year.