06.03.18
EMILY WAITE
The
bets on liquid biopsy keep
getting bigger. Last month, Silicon Valley unicorn Grail Inc.
raised a third round of financing to develop its blood-based tests for early
cancer detection. That brings its total up to $1.5 billion since 2016, putting
it among the top three most heavily funded private biotech companies in the US.
While
investors might be bullish on the risky venture, many oncologists have been
more skeptical about how well Grail’s technique might work. A spinout of DNA
sequencing giant Illumina, the
company aims to detect cancers beforesymptoms appear by using
“high-intensity” sequencing to pick out genetic material shed by lurking tumors
into the bloodstream. It’s an idea that Grail will shell out to test; most of its
investments will go toward the company’s two long-term, population-scale
clinical trials. And this weekend, with data from one of those trials Grail
give the doubters some reason to believe.
At one of the largest
annual gathering of cancer researchers, the American Society of Clinical
Oncologists conference in Chicago, Grail presented early results from its
Circulating Cell-free Genome Atlas study, which has so far enrolled about
12,000 participants from research centers like the Mayo Clinic and Memorial
Sloan Kettering. It’s the first look at how the company’s sequencing-based test
prototypes are performing.
Grail tried out three
methods on a substudy of about 1,600 people, about half who had been newly
diagnosed with 10 different tumor types, and half cancer-free controls. The
first test looked at changes in about 500 cancer-related genes. The second used
whole genome sequencing to identify larger genome rearrangements that can lead
to tumor development. And the third analyzed changes to the DNA’s that can turn
on cancer-causing genes.
The company shared
results of these methods, which were comparable across the three assays. Taken
together, the blood test correctly diagnosed people with ovarian and liver
cancers 80 percent of the time. It found lymphoma and myeloma with slightly
less accuracy. It was worst at detecting breast cancer, getting it right less
than a quarter of the time.
Grail’s
numbers are similar to what researchers behind other liquid biopsy
startups have published previously,
in places like Science. The difference here
is that ASCO presentations aren’t peer-reviewed and the underlying data doesn’t
have to be made available. So there are limitations on understanding the
veracity of Grail’s results. The company hasn't yet disclosed any plans to
publish in a peer-reviewed journal.
“This
is a discovery study so we really just wanted to understand how each test
performed across different cancers,” says Anne-Renee Hartman, Grail’s VP of
Clinical Development. “As we move forward we’ll be validating the test to see
how well it picks up cancer in groups that don’t have diagnoses.” Proving
liquid biopsy techniques can reliably detect cancer is just the first step
though. To be truly useful they have to also provide some information
about where the tumor is in
the body, as well as minimize false alarms. Biotech companies will also have to
make sure they can scale up to be cost-effective if there’s to be any future
for pan-cancer screens becoming a regular part of routine health care. In that
regard, Grail’s actually doing pretty well, at least on the Eastern Front.
When the company
launched in 2016, its first CEO, Jay Flatley pronounced that it would have its
first test on the market by 2019. Until recently, that seemed unlikely. Then,
last year Grail combined forces with Hong Kong-based screening startup Cirina,
which controls patents for a blood test that detects a cancer commonly found in
southern China called nasopharyngeal carcinoma. Key to that detection is a
virus associated with the disease—Epstein Barr. Tumor cells all carry bits of
the viral DNA inside them, which can easily be picked up via sequencing.
Grail is launching
that test later this year in Hong Kong—it will be the first liquid biopsy test
marketed for early detection. It’s a modest start for a company with
aspirations to create a single test for all the ways that cancer can riddle a
human body. But hey, it’s a start.
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