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 The findings, presented on Saturday at the American Society of
Clinical Oncology meeting in Chicago, show the new test by Grail, a
spinoff of gene sequencing company Illumina Inc, can identify bits
of cancer DNA in the blood of patients already known to have cancer.
The study is the first of many the company must perform as it aims
to develop a blood test to find early stage cancers in people with
no symptoms of the disease.
"It's an important first step. We show that what we call a
high-intensity approach works," said Dr. Pedram Razavi of Memorial
Sloan Kettering in New York, who led the study.
Most liquid biopsies use next-generation sequencing to scan blood
samples for fragments of tumor DNA in people previously diagnosed
with cancer.
Such tests, from a host of companies including Guardant Health Inc,
Foundation Medicine, Qiagen NV, Genomic Health Inc and Myriad
Genetics Inc, offer a non-invasive alternative to standard tissue
biopsies and are expected to be a multibillion-dollar market. They
are used to identify which genes are driving a person's cancer or
measure the effectiveness of treatment.
Cancer experts say it is difficult enough to find cancer DNA in the
bloodstream of patients with advanced tumors, but it will be far
more challenging to find rare cancer genes in blood from healthy
people.
To achieve this, Grail's test scans blood samples for mutations in
508 genes, reading each region of the genome some 60,000 times. The
company says the process yields 100 times more data than other
liquid biopsy approaches.
The company was formed in 2016 with $100 million in investments from
Illumina and others including Amazon.com Inc founder Jeff Bezos and
Microsoft Corp co-founder and philanthropist Bill Gates. In March,
the company said it had raised more than $900 million in financing.
For the feasibility study, researchers from Sloan Kettering and
Grail analyzed tissue and blood samples from 124 patients with
metastatic breast, lung, and prostate cancers, to see if the blood
test detected mutations that were identified in separate tests from
tissue biopsies.
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In 89 percent of patients, at least one genetic change detected in
the tumor was also found in the blood.
"Basically, what they're showing is that they can detect in blood
the majority of the same mutations that they can detect in tissue of
patients with advanced cancer," said Dr. Richard Schilsky, chief
medical officer of ASCO, who was not involved in the study.
Schilsky said the study is a first step in validating the test,
adding diagnosing early stage cancers from a blood test "is a very
high hurdle."
Even if Grail proves it can find early stage cancers, such a test
could create a challenge for doctors, who would need to find the
tumor so it could be removed. Razavi said scientists are already
considering that problem, too.
Mark Lee, head of clinical development and medical affairs at Grail,
said the company plans to use its test on hundreds of thousands of
people with and without cancer to map out the characteristics that
distinguish early stage cancers from normal DNA.
"The key is going to be data," Lee said.
(Reporting by Julie Steenhuysen; Editing by Lisa Shumaker)
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