Such "tumor-agnostic" drugs from companies including Merck & Co and
Loxo Oncology may help overcome misgivings by health insurers, who
have balked at covering large-scale tests looking for genetic
mutations in tumors, and quell concerns of some top cancer doctors
who question whether enough patients benefit from such tests.
Last month, Merck's immunotherapy Keytruda became the first cancer
treatment ever to win U.S. approval based on whether the tumor
carried a specific genetic glitch, irrespective of the tumor's
location.
More recently, Loxo showed that its drug larotrectinib helped shrink
tumors in 76 percent of patients with a wide variety of advanced
cancers who carried a specific genetic defect.
The surprising results suggested a benefit of testing many patients
for the same defects.
"Insurance companies had an easy out" before the Merck approval and
Loxo data, said Dr. David Hyman of Memorial Sloan Kettering Cancer
Center in New York. Hyman presented the Loxo results at the American
Society of Clinical Oncology annual meeting last weekend.
"They have asked, 'Show me the evidence this helps patients.' It
didn't exist," he said. "Now we have these data."
A second company, Ignyta Inc, has developed a drug that targets the
same genetic glitch as Loxo’s larotrectinib, and both treatments are
under expedited review by U.S. regulators.
At the U.S. Food and Drug Administration, cancer chief Dr. Richard
Pazdur said he is "very supportive" of the tumor-agnostic approach
and believes more such approvals are likely.
"What we're seeing is the result of a lot of work that has been done
to determine how these drugs work," Pazdur told Reuters.
Such evidence may begin to sway insurers, but it's not clear how
quickly. Aetna Inc said it is studying the Keytruda approval and
will base its decision about testing based on the medical evidence
and whether the treatments improve quality, reduce waste and provide
members with access to affordable care.
Dr. Jeffrey Hankoff of Cigna Inc said the company "generally does
not cover multi-gene panels" unless they are recommended by the
National Comprehensive Cancer Network, a nonprofit group that sets
cancer treatment guidelines.
"Ultimately, it's a matter of having actionable information from
genetic testing that is based on evidence, not on conjecture,"
Hankoff said.
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ENTHUSIASM WANING
In 2001, Novartis drug Gleevec transformed the treatment of chronic
myelogenous leukemia (CML) from a fatal blood cancer to a treatable
condition for most patients. The drug takes aim at a single genetic
defect, raising hopes for a new age of targeted drugs that work
better and more safely than traditional chemotherapy. Since then,
gene sequencing has become exponentially faster and cheaper. Five
years ago, companies such as Foundation Medicine introduced genetic
profiling tests that look for a range of cancer-causing genes to
match patients to a handful of targeted drugs for lung, skin and
breast cancer or to clinical trials testing new agents.
Many doctors have embraced the practice, hoping to find a treatment
for patients with advanced cancers who were out of options. But
insurers have been slow to pay for the tests, which cost $1,000 to
$5,000 and can result in the off-label use of targeted drugs with no
evidence that they work.
In late 2015, a randomized trial showed such testing yielded no
survival advantage compared with conventional therapy. The finding
triggered a fierce debate in medical journals, with some experts
questioning whether hype has gotten ahead of the science.
"There are patients that benefit, but it's very much a minority of
the patients," said Dr. Scott Kopetz, a colorectal cancer specialist
at the University of Texas MD Anderson Cancer Center.
Hyman argues that the Keytruda approval based on a single genetic
defect "changed the field overnight" and will gain momentum with the
likely approval of larotrectinib, which targets a defect called TRK
fusions.
Experts estimate up to 1 percent of all cancer patients have TRK
fusions.
Dr. John Heymach, an oncologist from MD Anderson Cancer Center in
Texas who was not involved in the Loxo study, said it underlines
"the importance of expanding what we're looking for."
(Reporting by Julie Steenhuysen; Editing by Michele Gershberg and
Cynthia Osterman)
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