Visual credit:University
of Aberdeen |
Genetic testing can tell doctors
whether to prescribe the common chemo drug docetaxel
to their breast cancer patients, says a Scottish study
presented at the European Cancer Conference (ECCO) on
September 24, in Barcelona.
Two genes in breast cancer cells
determine which tumours will respond to docetaxel and
which will become resistant. "We hope that in the future
this will mean that before we treat patients with breast
cancer with docetaxel, we can predict whether the drug
will work or not, using a very simple test," co-author
Dr Andy Schofield said in a University of Aberdeen release.
The study will be published i n an upcoming European
Journal of Cancer Supplement.
PREDICTED
RESPONSE
Up to half of all advanced breast cancer patients who
use docetaxel end up developing resistance to it and
treatment fails, according to Dr Iain Brown, lead author.
Researchers took two human breast
cancer cell lines and made them resistant to docetaxel
by exposing them to very high concentrations of the
drug. They then looked at the genetic make-up of those
cells to see which genes are involved in developing
resistance.
"For the first time, we have found
two genes that identify which breast cancer cells respond
to chemotherapy and which do not respond," Dr Schofield
said.
SPARED
THE SIDE-EFFECTS
The test would mean that those who wouldn't benefit
from docetaxel chemotherapy could be spared its severe
side effects, said Dr Brown They could also be eligible
for other, more experimental drugs. The aggressive drug
is brought in when breast cancer cells metastasize,
after other chemo drugs stop working. It can lead to
liver damage, in addition to common chemo side effects
like hair loss and low white blood cell count.
Predicting response would also
reduce costs for healthcare providers, according to
Dr Brown. Many women on the drug are suffering the side
effects with no benefit whatsoever from the medication.
A personalized approach would allow docs to switch them
to more effective meds right away, without incurring
the expense.
But the research has only been
done on cells in the lab so far. Next step is translating
the findings into a clinical setting before a genetic
test is developed. "If we find the same results in patient
samples, we would expect that a simple test for predicting
who would benefit from docetaxel could be developed
and in clinical use within the next five years."
PERSONALIZED
TREATMENT
"The ultimate aim is to develop individual treatments
for breast cancer patients, as opposed to a one size
fits all approach," said Dr Schofield. "At the moment
it is a bit of a lottery as some patients strike it
lucky with their treatment. We want everyone to be a
winner."
This would be the second coup for
personalized medicine in the breast cancer treatment
arena. The first came with trastuzumab, a drug that
targets tumours in HER-2 positive breast cancer patients.
An estimated 22,300 Canadian women
will be diagnosed with breast cancer this year. The
disease kills more than 100 every week. A combination
of surgery, radiation and chemotherapy is used to treat
it.
"We think that the changes we have
found may also allow us to predict which patients would
respond to other commonly used chemotherapy drugs, not
just docetaxel," said Dr Brown.
The researchers at the University
of Aberdeen are already checking for similar results
in other cancers. Docetaxel is also used as a second-line
treatment in advanced lung cancer.
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