Novel Drug Combo Improves Breast Cancer Survival
From Associated Press (December 12, 2009)
SAN ANTONIO--Some women with very advanced breast cancer may have a
new treatment option. A combination of two drugs that more
precisely target tumors significantly extended the lives of women
who had stopped responding to other medicines, doctors reported
Friday.
It was the first big test of combining Herceptin and Tykerb. In a
study of 300 patients, women receiving both drugs lived nearly five
months longer than those given Tykerb alone.
Doctors hope for an even bigger benefit in women with less advanced
disease, and were elated at this much improvement for very sick
women who were facing certain death.
"We don't see a lot that works in patients who have seen six prior
therapies as they did in this trial, so that alone is exciting,"
said Dr. Jennifer Litton, a breast cancer specialist at the
University of Texas M. D. Anderson Cancer Center.
The good results are in stark contrast to two other studies that
found no survival advantage from Avastin, a drug whose approval for
breast cancer patients was very controversial. Two infusions of
Avastin a month, as needed for this treatment, can run as much as
$30,000 with fees for administering the drug. Its maker, Genentech,
says the wholesale price it charges for the drug averages $7,700 a
month.
Considering Avastin's potential side effects _ blood clots in the
lungs, poor wound healing, kidney problems _ a survival benefit
"would have made the cost of the drug less painful to take," Litton
said.
She had no role in any of the studies, which were reported Friday
at the San Antonio Breast Cancer Symposium.
Herceptin and Tykerb aim at a protein called HER-2 that is made in
abnormally large quantities in about one-fourth of all breast
cancers. Herceptin blocks the protein on the cell's surface; Tykerb
does it inside the cell.
"It's kind of like having a double brake on your tumor. If the
first one fails, the second one does the job," said Dr. Kimberly
Blackwell of Duke University. She led the combo treatment study and
has consulted for its sponsor, British-based GlaxoSmithKline PLC,
which makes Tykerb, and for Genentech, which makes Herceptin and
Avastin.
Women in the study had already received Herceptin alone or with
various chemotherapy drugs and still were getting worse. They were
randomly assigned to receive only Tykerb or both drugs, to see
whether the combo might help Herceptin regain its
effectiveness.
Median survival was analyzed after about three-fourths of the women
had died _ roughly two years after the study began. It was 61 weeks
in the combo group versus 41 for those taking only Tykerb.
That likely underestimates the combo's true benefit because women
on Tykerb alone were allowed to add Herceptin partway through the
study if they continued to worsen, and many of them did, Blackwell
said.
One woman on the combo in the study suffered a fatal blood clot.
The only other common, serious side effect was diarrhea, which
plagued 7 to 8 percent of each group. Herceptin costs about $10,000
a month; Tykerb, $5,000 to $6,000.
Dr. Eric Winer, breast cancer chief at the Dana-Farber Cancer
Center in Boston, said several studies now show that Herceptin
still helps women even when their cancers seem to be getting
worse.
"Herceptin is like a big roadblock on a superhighway. Eventually
the cancer finds a way around it by taking an off ramp. But it's
much less efficient to take that off ramp, so Herceptin is still
having some influence on that cancer," said Winer, who, like
Litton, has no financial ties to any drugmakers.
"Herceptin is a drug that keeps on giving," he said.
Not so for Avastin, which works by crimping a tumor's blood supply.
The federal Food and Drug Administration approved its use in women
whose cancers had spread beyond the breast over the objections of
FDA advisers who wanted more evidence of benefit for these
patients.
Now, two big international studies show that Avastin modestly
delayed the time breast cancer took to worsen, but had no effect on
overall survival.
Avastin also is approved to treat certain lung, brain and colon
cancers, and the new studies have no bearing on its use in those
patients.
The cancer conference is sponsored by the American Association for
Cancer Research, Baylor College of Medicine and the UT Health
Science Center.
___
On the Net:
Cancer conference: http://www.sabcs.org
Patient information: http://www.cancer.net
American Cancer Society: http://www.cancer.org
Posted: December 2009
