hemotherapy
treatment for people who have advanced bowel cancer and a particular genetic
mutation is commonly ineffective. A combination of three different drugs could
be the key to improved treatment.
The outlook for people with standard bowel cancer — also
known as colorectal cancer — and those with an advanced form of the disease can
differ greatly.
While more than half of the former tend to survive bowel cancer
for 10 or more years, the outlook for the latter can be
just a few months if the cancer involves a specific gene mutation.
The BRAF gene is responsible for producing a protein that
transmits signals and supports cell growth. But a particular change to this
gene — the BRAF V600E mutation — can speed up the spread and growth of certain
cancer cells.
Up to 15% of metastatic colorectal cancer (mCRC)
patients have the BRAF V600E mutation. Treating this form of cancer is
difficult as it can be aggressive and tends not to respond to combination
treatments involving chemotherapy.
The potential power of triple therapy
Now a new study has tested a combination of targeted therapies
without the chemotherapy. Researchers call this the BEACON CRC Phase III trial.
Their study appears in the Annals of Oncology and
featured at the ESMO World Congress on Gastrointestinal Cancer 2019.
A mixture of three drugs — two targeting the cancer cells and
one inhibiting the BRAF gene — was analyzed on a number of individuals who had
not responded to one or two previous treatment regimes.
There were 665 participants in total. Researchers gave some all
three drugs: encorafenib, cetuximab, and binimetinib. Others had a double
therapy of BRAF inhibitor encorafenib and cancer-treating cetuximab.
A third group received a choice of the chemotherapy drug
irinotecan or folinic acid, fluorouracil, and irinotecan (FOLFIRI) and
cetuximab.
"Colorectal cancer does not respond to BRAF therapy alone
because tumor cells adapt
through other mechanisms after initial treatment," explains Dr. Scott Kopetz, study author from the
University of Texas MD Anderson Cancer Center in Houston.
"With this triple targeted therapy, we are using a very
scientifically logical combination to inhibit BRAF and these other
mechanisms."
Longer survival and better response
The focus was on triple therapy, and this proved to be the most
successful option. While standard therapy gave a general survival rate of 5.4
months, the three-drug combination provided a median survival rate of 9 months.
The response rate showed even greater improvement at 26% for the
triple therapy versus just 2% for the standard regime.
The researchers did not compare the triple and double therapies,
but the two-drug combination gave a general survival rate of 8.4 months.
Dr. Kopetz describes the findings as
"very exciting because we've been trying to target BRAF-mutant colorectal
cancer for many years."
"Hopefully, this will soon lead to increased access to this
treatment for patients where there is currently such a large unmet need."
A replacement for chemotherapy?
Although future studies will need to look at whether double or
triple therapy is best for individuals, researchers believe that the three-drug
treatment should replace chemotherapy for those with a BRAF mutation.
"The fact that we can give this targeted combination
without the need for chemotherapy is very good news for patients, not least
because of the side effects that they typically experience with
chemotherapy," notes study co-author and professor Andres Cervantes from
the Biomedical Research Institute INCLIVA at the University of Valencia, Spain.
It is also, therefore, "essential that patients are
routinely tested" for the mutation.
Prof. Cervantes adds that, for the time being, they should
restrict targeted therapy to those individuals treated in the BEACON CRC trial
who have progressed after one or two earlier lines of chemotherapy.
No comments:
Post a Comment