THURSDAY, Dec. 12, 2013 (HealthDay News) -- Adding the cancer
drug dasatinib to standard hormone therapy may slow the progression
of advanced breast cancer, a preliminary study suggests.
The drug, sold under the name Sprycel, is already approved in
the United States for chronic myelogenous leukemia. Experts said
it's too early to say whether it should be added to the treatment
arsenal for breast cancer, but they called the findings from this
early study promising.
The study included 120 postmenopausal women with either a breast
cancer recurrence or metastatic cancer -- meaning it had spread
from the breast to the bones or other sites in the body.
Overall, women who received Sprycel along with hormonal therapy
remained progression-free for twice as long as those given hormonal
therapy alone: typically 20 months versus 10 months.
Experts said the findings, presented this week at the San
Antonio Breast Cancer Symposium in Texas, are "encouraging." But
more research needs to be done.
"It's a small study, and this is not ready for prime time yet," said lead researcher Dr. Dev Paul, a breast cancer specialist at U.S. Oncology and Rocky Mountain Cancer Centers in Denver.
He said a big question is, can doctors find a way to identify
the particular women who stand to benefit from Sprycel? The drug
targets a protein called Src (pronounced "serk"). And it's thought
that in some women activity in that protein contributes to the
spread of breast cancer to the bones.
But right now, there's no known indicator, or "biomarker," in
the blood that can be measured to gauge a patient's Src activity,
Dr. Elias Obeid, a breast cancer specialist at Fox Chase Cancer
Center in Philadelphia, agreed on the need for a Src indicator.
Women with advanced breast cancer can live for several years
with current treatments. And for any one woman, Obeid explained,
you have to weigh the potential benefits of a new treatment against
"That balance is very important," said Obeid, who was not involved in the study. "We have to be looking at quality of life."
In this study, close to 40 percent of women on Sprycel had
fatigue or nausea. About one-quarter had anemia or rash, and 16
percent had fluid buildup around the lungs, which can cause chest
pain and breathlessness, and require treatment to drain the
"Those side effects can be significant," Obeid noted.
Sprycel is among the wave of new cancer drugs designed to be
"targeted" therapies. They zero in on particular proteins in cancer
cells, which, it's hoped, will allow them to be more effective and
less toxic than conventional chemotherapy.
The women in the current study all had hormone receptor-positive
breast cancer, which means estrogen and progesterone help fuel the
cancer's growth. Most cases of breast cancer (about 75 percent) are
Hormone-blocking drugs, such as tamoxifen, are the standard
treatment for recurrent or metastatic breast cancer. "Most women
initially respond to the hormone therapy," Paul said. "But
eventually they become resistant."
It's thought that activity in the Src protein is one way the
cancer develops resistance and continues to progress. So Paul's
team reasoned that adding Sprycel might boost the effectiveness of
Of the women in the study, 63 were randomly assigned to standard
hormone therapy with the drug letrozole (Femara), and 57 to Femara
Sprycel actually brought no extra benefit when it came to the
number of women who saw their cancer shrink, or at least had no
progression for six months or more. More than 60 percent of women
in each group had those responses.
The difference was seen in "progression-free survival" -- the
typical amount of time the women showed no cancer progression --
which was 10 months longer for women on Sprycel.
While that's an encouraging finding, "it's too early to jump on
this," said Dr. Subhakar Mutyala, associate director of the Scott
& White Cancer Institute in Temple, Texas.
Mutyala, who was not involved in the study, agreed that because
women with metastatic breast cancer can live for a number of years,
the side effects of any new treatment are "really important" to
"Right now, we can say dasatinib [Sprycel] shows activity in these patients," Mutyala said. But the drug's ultimate benefit for women's lives is not clear, he added.
And like other targeted cancer drugs, such as Gleevec and
Tasigna, Sprycel rings up at around $100,000 or more a year in the
Bristol-Myers Squibb, which markets Sprycel, funded the study.
Paul said he has no financial conflicts of interest.
The U.S. National Cancer Institute has more on
metastatic breast cancer treatment.
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