MONDAY, Oct. 1 (HealthDay News) -- Cancer treatment could one
day be more effective and less difficult to endure if an
experimental breast cancer therapy that offers high-precision
targeting of tumors proves successful.
The new approach uses a unique three-pronged combination of
agents that simultaneously attack cancer cells but prevent the
release of chemotherapy until the drug reaches its specific target,
said the authors of a new study on the technique.
As a result, the treatment attacks cancer with greater power and
effectiveness, yet less toxicity, so patients experience fewer side
effects, such as nausea and vomiting, hair loss and infections, the
study authors said.
The drug therapy, called T-DM1, appears to be effective in
prolonging life and reducing tumor growth with less impact on the
body's healthy cells in a significant proportion of women in the
late stages of a specific kind of breast cancer known as
HER2-positive. It has not yet been approved by the U.S. Food and
T-DM1 is what's known as an "antibody-drug conjugate," designed
to deliver potent anti-cancer drugs to tumors while limiting
toxicity to healthy cells in the body.
"This is a new model for attacking cancer," explained study author Dr. Sunil Verma, a medical oncologist at Sunnybrook Odette Cancer Centre and an assistant professor at the University of Toronto. "It opens up the doors for antibody-drug conjugates to be used potentially with early-stage breast cancers, lung, colon and colorectal cancers," he said.
Breast cancer is the most common female cancer in the United
States. Up to 20 percent of women with breast cancer have tumors
that have high levels of HER2, which is a protein that is involved
in cell growth, differentiation and blood vessel formation, Verma
The experimental drug is made up of trastuzumab (Herceptin, an
existing breast cancer drug) and the cancer-cell-destroying agent
emtansine (DM1), plus a substance that prevents the drug from
becoming active until it reaches the targeted cancer cells.
Trastuzumab delivers DM1 to the tumor where it kills cells
overproducing HER2, Verma explained.
By combining these components, T-DM1 targets cancer cells while
minimizing harmful side effects, he said.
In the case of HER2-positive cancer, the antibody-drug conjugate
includes Herceptin. But with other forms of cancer, the antibody
could be different, depending on the genetic composition of the
cancer, Verma explained.
The research was published online Oct. 1 in the
New England Journal of Medicineand was scheduled for
presentation Monday at the European Society for Medical Oncology,
In the study, a phase 3 trial, 991 patients with HER2-positive
breast cancer were randomly assigned to receive either T-DM1 or
standard therapy: the anti-cancer drugs lapatinib (Tykerb) and
cepecitabine (Xeloda). All the participants had locally advanced or
metastasized breast cancer previously treated with Herceptin and a
taxane, a type of drug that blocks cell proliferation by stopping
cell division, the study authors said.
Of the participants, 43.6 percent of those on T-DM1 had tumor
shrinkage, while 30.8 percent of those on the other medications
did. Mean progression-free survival was 9.6 months in the T-DM1
group compared with 6.4 months among those getting standard
"That's significant," said Verma. "And this improvement comes with less toxicity and fewer side effects."
Dr. Daniel Hayes, clinical director of the breast oncology
program at the University of Michigan Comprehensive Cancer Center,
said the question is whether this three-pronged approach will be
effective with other cancers.
"We don't know yet, but it's likely," he said. "But people will definitely benefit from this drug."
Hayes said that while science has made remarkable progress
against breast cancer during the last 30 years, "we still have
30,000 to 40,000 women die of breast cancer every year. We need to
To learn more about
breast cancer, visit the U.S. National Cancer Institute.
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